All Miller Audio, LLC Custom Amplifiers are built to order and require deposit to begin, and final payment before shipping.

Base Price ($2350.00)

WHATS INCLUDED:

All units come with a black powder coated chassis, black transformer covers, manual bias system, new production tubes, a standard terminal block with no markings, and black octal sockets. Capacitor options include Solen or Mundorf Caps at no additional cost. Upgrade Options available via checkout form.

***Faceplate not included - Trim package selection required***

*** NEW OLD STOCK VACUUM TUBES AVAILABLE - CONTACT TO PLACE YOUR AMP ORDER. SHOWN CONFIGURATIONS ARE FOR NEW PRODUCTION TUBES ONLY! ***

Miller Audio LLC announces its new line of Dyna-70 Ultimate Audio System amplifiers. Made here in the U.S.A., you get a classic product, based on the world’s best-selling tube amplifier, with the latest in 21st century electronics plus a newer, modern look that will look at home in any living room, entertainment / TV / Game room or mancave. The electronics are the same great sounding circuits, regardless of the finish color or trim, and these amplifiers come in either Manual or Automatic Bias versions which feature individual bias settings for each power tube.

All Miller Audio, LLC Custom Amplifiers are built to order and require deposit to begin, and final payment before shipping.

Base Price ($1950.00)

WHATS INCLUDED:

All units come with a black powder coated chassis, black transformer covers, manual bias system, new production tubes, a standard terminal block with no markings, and black octal sockets. Capacitor options include Solen or Mundorf Caps at no additional cost. Upgrade Options available via checkout form.

***Faceplate not included - Trim package selection required***

*** NEW OLD STOCK VACUUM TUBES AVAILABLE - CONTACT TO PLACE YOUR AMP ORDER. SHOWN CONFIGURATIONS ARE FOR NEW PRODUCTION TUBES ONLY! ***

Miller Audio LLC announces its new line of Dyna-70 Ultimate Audio System amplifiers. Made here in the U.S.A., you get a classic product, based on the world’s best-selling tube amplifier, with the latest in 21st century electronics plus a newer, modern look that will look at home in any living room, entertainment / TV / Game room or mancave. The electronics are the same great sounding circuits, regardless of the finish color or trim, and these amplifiers come in either Manual or Automatic Bias versions which feature individual bias settings for each power tube.

All Miller Audio, LLC Custom Amplifiers are built to order and require deposit to begin, and final payment before shipping.

Base Price ($1700.00)

WHATS INCLUDED:
All units come with a black powder coated chassis, black painted transformer covers (no face plate), manual bias system, a standard terminal block with no markings, new production tubes, and black octal sockets. Capacitor options include Solen or Mundorf Caps at no additional cost. Upgrade Options available via checkout form.

*** NEW OLD STOCK VACUUM TUBES AVAILABLE - CONTACT TO PLACE YOUR AMP ORDER. SHOWN CONFIGURATIONS ARE FOR NEW PRODUCTION TUBES ONLY! ***

Miller Audio LLC announces its new line of Dyna-70 Ultimate Audio System amplifiers. Made here in the U.S.A., you get a classic product, based on the world’s best-selling tube amplifier, with the latest in 21st century electronics plus a newer, modern look that will look at home in any living room, entertainment / TV / Game room or mancave. The electronics are the same great sounding circuits, regardless of the finish color or trim, and these amplifiers come in either Manual or Automatic Bias versions which feature individual bias settings for each power tube.

The Automatic Bias Module (ABM) is made by Auto Amp in Croatia. We use a modified module, made for Miller Audio LLC, to fit the Dyna-70 Ultimate Upgrade PCB, maintaining the factory warranty for the module.  The module comes with the bias preset and tested to ensure proper operation.  We recommend following our detailed installation instructions for the Dyna-70 Ultimate Upgrade Assembly Manual, v1.0.

While our Auto Bias Modules were designed for use with the Dyna-70 Ultimate Upgrade Kit, they can be used with other ST-70 driver upgrade PCB’s. Contact us for details prior to ordering, we can help ensure you get the right components needed for successful integration.

CAUTION: Exercise care in handling and installing the bias module. It is important to avoid generation of static electricity and ground your body when around static sensitive components and assemblies. Handle the module like a vinyl record, around the edges, trying not to touch any of the board components. The Module comes packaged in an electro-static protective packaging; always keep the module in this package until ready to install. Make sure that you always touch metal (a work bench or the ST-70 amplifier chassis) to stay grounded. Use ground straps on your body (shoes and wrists) to ensure you drain all static electricity away from yourself before handling the module to install it.  Digi-Key and Mouser Electronics sell anti-static grounding items for electronic assembly.  Anti-Static items are inexpensive and a worthy item to have around your work bench.

NOTE: Bias modules have no user serviceable components. Tampering with the module in any manner will void the warranty.  Improper handling and exposing the module to static electricity will also void the warranty.

The RCA 6SN7 GTB are great sounding tubes. These are the Black Plate version that will liven up any audio piece that uses 6SN7 tubes. We have broad selection of RCA tubes and sell them for less than most vacuum tube specialty shops.

This is the coin base version of the GE 6SN7GTB and was one of the later production 6SN7’s.  This tube is also available in a standard octal base version but is basically the same tube.  Note it is taller than most 6N7’s.

CBS-Hytron was a high quality USA tube manufacturer, yet their production numbers were much smaller than the big name vacuum tube brands such as RCA, Sylvania, GE, etc. The CBS Hytron construction is easy to identify: Clear Top design, Black Plates, the famous hole in the plastic key pin, and the getter shaped like a `square D`.

The JJ Electronic 6SN7 is the classic double triode with a rugged construction the offers the high reliability that JJ is known for. The JJ 6SN7 features the outstanding linearity and sound of the original 6SN7 tubes. This tube is an excellent replacement for Hi-Fi amplifiers and preamps and will replace any 6SN7, 6SN7GTA, 6SN7GTB, or 6SN7GT.

Tung Sol 6SN7GTB dual triode preamp tube features super linearity, low noise, and full performance ratings make this one of the best new production 6SN7 tubes made. The sound signature is comparable to 5692 tubes. Excellent driver tube for high-end audio applications.

JJ Electronic EL34 features a rugged construction leading to an incredibly dependable EL34 with astonishing tone. The sound is balanced with tight lows, a rich and dynamic mid-range, and clear highs. The JJ EL34 is a great replacement for guitar and stereo amplifiers. EL34 tubes offer dependable performance with tight lows, rich mid-range, and clear highs, perfect for guitar and stereo amplifiers.

JJ Electronic E34L adds more power to a standard EL34 due to its higher grid voltage rating. This increase gives the tube more headroom and a tighter response on the low end. The wide frequency response of this tube offers excellent harmonics that work in a variety of genres for guitar and power amplifiers.

JJ Electronic E34L adds more power to a standard EL34 due to its higher grid voltage rating. This increase gives the tube more headroom and a tighter response on the low end. The wide frequency response of this tube offers excellent harmonics that work in a variety of genres for guitar and power amplifiers.

The JJ EL34 II features a different construction from the classic EL34 tube, offering a different tonal palette from the original EL34. The EL34- II tube has a more compact plate structure than standard EL34’s, with an increased low to low-mid end with plenty of headroom to spare. This tube has a thick and tight bass response. The mids are balanced and harmonically rich with pleasantly smooth highs. The JJ EL34 II is stronger than the original but not harsh sounding.

The JJ 6CA7 is a true reproduction of a classic U.S.A. designed EL34 tube that will work in most EL34 amps. Sonically, this tube is closer to a 6L6 than an EL34 but without the sometimes harsh high end of the 6L6. The JJ 6CA7 offers warm highs with punchy articulate mids and tight lows. Wielding even more power than a KT77, this tube is a great choice for people looking for a change in their EL34 amp’s tone or want to push their levels that much further.

The JJ Electronic KT77 is a reproduction of the original tube that made the KT77  tubes famous. JJ has built this tube with a solid construction that is robust and reliable. This tube has more headroom than a typical EL34. The low end is fat and defined with detailed, responsive mids and smooth highs. This is an excellent tube for adding more power to the sound of an EL34 amp.

Premium high-voltage power pentode, featuring improved materials and workmanship over the original EL34B. Higher impedance design with increased touch responsiveness.

• Unique clipping characteristic with a hint of 6L6 sound

• Velvety-smooth in HiFi applications, full & rich-sounding in guitar amps

• 6CA7 equivalent

If you’re curious about the EL34-L Power Tubes and EL34 II Power Tubes, we’ve got you covered. Check out these products as well to discover their unique features and find the perfect fit for your audio needs.

Tech Data

We found the perfect termina block for a Dynaco product; it fits the ST-70 (and other Dynaco amplifiers) as if it were made for it- no holes to drill or enlarge- just bolt it right on. The following are photos of our development ST-70 chassis. To those Pomona banana jack adapters; we like them and will to use them, but at their cost most customers will not buy a full set of eight- because you can only hook up one set of speakers on a ST-70. All one really needs are 2 black and 2 red adapters, cutting the cost in half and giving customers all they need to use the new terminal blocks with banana jacks. This installation protects the Fuse and the power switch because the terminal block extends past both the power switch and the fuse body. Note that the individual terminals are separated by a molded-in barrier, aiding in the prevention of stray wire strands from shorting across speaker terminals, a great improvement over the stock terminal strip and something not addressed when using those big, chunky plastic imported binding posts. Reminder: These terminal blocks will bolt right up to Dynaco Mark II, III and IV mono block amplifiers too. We'll be releasing these soon and welcome customer feedback. We will have available in our demo room at the Lone Star Audio Fest,June 2-4 here in Dallas at the Embassy Suite Hotel- Galleria near I-635 and the North Dallas Tollway. Stop by and check out all our products,listen to some tunes from one of our Dyna-70 Ultimate Upgrade ST-70's and see if you don't agree we have the best sounding ST-70 on the market today.

Recently we found these banana jack screw-in terminals made by Pomona Electronics, a subsidiary of Fluke. If you have, or shopped for Fluke products, you know they are well made and are extremely reliable and high quality, however there is nothing inexpensive about Fluke. These are made in 6/8/10-32 thread sizes. The standard screw terminal strip used in the ST-70 uses 6-32 machine screw threads. Here is a link to the 5699 series "Terminal Strip Banana Jack Adapter" specification sheet.What is wonderful for customers, all you do is take a screwdriver, unscrew the old terminal screws on your ST-70 speaker terminal strip, and screw in these banana jack adapters, snug them a little and you're done. Easy, simple, and you don't have to remove the tube cage or bottom cover to unsolder wires internally to install banana jack binding posts- see our engineering prototype adjacent to this paragraph. You can update your speaker terminals easily- no need to break out a soldering iron, solder, wire strippers, etc. This also saves you money in labor costs; there's no need to take your ST-70 to your local electronics tech to swap out the terminal strips and install binding posts. This seems great, right? Recall that mention of Fluke and how expensive they can be? Hold your breath, because these banana adapter posts are about $8 each, $64 for a complete set of 8 for an ST-70, plus S&H and sales tax. Now, since one can only use one pair of speakers on an ST-70, you really only need 4 adapters, cutting the cost in half. Unique, different, high quality, and with an impressive specification sheet, but not inexpensive. You can use them for clamp-style attachment using spade terminals if you so desire. Or unscrew them and put back your original 3/8 inch long, 6-32 pan head slotted screws if you sell your ST-70 and use the Pomona banana jack adapters on your next amplifier. We stress that these should be treated like a screw-in insert that converts your terminal strip to a banana jack connection. It's not intended to be used as a screw-type clamp fastener. You still need to be concerned about over tightening this banana jack post and stripping the threads. If you should strip it, you can't easily put a nut on the backside of the post threads and snug it up – however there is no room for a nut; you can try to bend the solder tab out of the way, at the risk of breaking the phenolic/paper strip.However, let's consider from a different perspective; if you were to bring your ST-70 to our shop and ask us to remove your old speaker terminal strips and install more up-to-date speaker binding posts, we can assure you that you would spend about $85 – $100 total, for parts, labor & sales tax. When you consider on those terms, we think it’s a good alternative if you want banana jacks and assuming you do the conversion, saves time, money, and the hassle of installing all new binding posts that don't permit you to use all the outputs Dynaco designed into the ST-70. Note: If you have a terminal strip with stripped threads, or a terminal nut that has worked its way loose in the insulator strip, or if the insulator is cracked or broken, you must replace with a new terminal strip before using the Pomona screw-in banana jack. Do not attempt to use in a substandard installation; you can do serious damage to the amplifier, speakers or both should you have a short.

This is the perfect Speaker Terminal Block for our Dyna amplifier products; it fits the ST-70 (and other Dynaco amplifiers) like they were made for it- no holes to drill – just bolt it right on with the supplied fasteners. These Terminal Blocks will protect the Fuse Body and the Power Switch from being bumped & damaged because the terminal block extends past both the power switch and the fuse body.

Note that the individual terminals are separated by a molded-in barrier. This prevents stray wire strands from shorting across speaker terminals, prevents spade terminals from touching and they accept screw-in banana panel jacks to make interfacing with speakers a breeze. These terminal blocks will bolt right up to Dynaco Mark II, III and IV mono block amplifiers, as well as some HeathKit, Marantz and Harmon Kardon tube amplifiers

The Dyna-70 Ultimate Upgrade uses Polypropylene Film Capacitors in the Audio Front-End and for the Power Tube film coupling capacitors. However, DIYer’s, experimenters & kit builders like to roll more than just vacuum tubes and the Dyna-70 Ultimate Upgrade PCB was designed with this interest in mind. The film coupling caps, C8, C9 & C10 have generous area to accommodate diverse sizes of film caps. We recommend for best performance that you not use film caps with less than a 630 VDC rating, or more than a 5% tolerance factor.

The Dyna-70 Ultimate Upgrade uses two sizes of film coupling caps, 0.10uF and 0.22uF; with two 0.10uF caps for C8 and four 0.22uF caps for C9 & C10. For those who want to experiment with film caps and their impact on the audio signature, we offer many upgrades to the Mundorf or Solen film polypropylene capacitors; our recommendation is to call us if you want something custom. Additionally, the Mundorf caps have a tighter tolerance of 3% vs. 5% for the Solen. Some of our customers are old school and prefer to use traditional Sprague Orange Drop Polypropylene film caps and that is all right with us because they too will fit fine on the Dyna-70 PCB.

For customers with discriminating taste, we offer what we think is the best audio film capacitor made, the Audio Note Copper Film capacitor.  These feature copper plated mylar foil, immersed in oil and also feature 99.9% pure Silver leads. From amplifiers to speaker crossovers, use of these film capacitors will take your audio product to another level, however we readily admit they are very expensive, but are on par, if not slightly better, than high-end Mundorf film capacitors (1200VDC Silver and Gold in Oil) we’ve used in several custom orders and are about the same price as the Audio Note Copper capacitors.

We normally use Audio Note, Audyn, Mundorf, and Solen film caps in all versions of the Dyna-70 upgrade and observe that al brands perform well, sound great and give owners the ability to customize their ST-70 using audio specific film caps.

NOTE:  We recommend you avoid use of capacitor voltage ratings above 1200-1400 volts; the size of the cap gets much larger in length & diameter. We provide room for C9 and C10 to accommodate most any film capacitor size, however, C8 is bounded by the 6SN7 tube sockets, limiting the physical size of cap that can be used in C8. For an additional cost we can provide closely matched sets of all film capacitors.

Dyna-70 Ultimate Upgrade “Upgrades” 

If the Dyna-70 Ultimate Upgrade itself is not enough to satisfy your quest for the best sounding ST-70, we offer the following items to further improve and expand the high-fidelity performance qualities of your Dyna-70 upgraded ST-70. This involves component replacements, where we have taken the extra time & effort to hand match components for use in both left and right channel circuits of the Dyna-70 PCB, increasing the probability of your hearing and capturing those subtle, background musical nuances, whisps of human voices, missed notes, out of rhythm bars, etc. As we play familiar old recordings, we discover new sounds all the time; minuet notes we have not heard before, or so long ago we forgot about them. Next, we bet you will find you need better recordings because you will hear more “junk” also, LP’s being one the best examples of poor recordings made back in the ’70’s. It is what makes us all Audiophiles!

Matched Film Coupling Caps

Available for our stock Audyn, Mundorf or Solen Polypropylene film capacitors. This involves someone grabbing a bunch of caps and measuring them all, then culling caps in groups to make matched sets. Not hard to do with the 2, C8 film caps, but harder to do with 4, C9/10 caps, requiring a much larger set of caps to start with.

NOTE: If you wish to incorporate this upgrade after purchasing a Dyna-70 Ultimate Upgrade kit, just send us back the supplied film caps and we will exchange at no cost for the caps. This assumes you purchased a standard kit equipped with Audyn film caps. You can also “trade” your new Audyn caps in (must be new, un-used and returned in same condition as received), and we give you full retail credit towards Solen or Mundorf caps upgrade, you just pay the difference in cap price, plus the $35 matching labor charge, as well as shipping and handling.

The Dyna-70 Ultimate Upgrade  with  Automatic  Bias  (AB or Auto Bias) is the newest version of the Dyna-70 Ultimate Upgrade kit. Now you can enjoy the convenance of not having to check your output tube bias again. Observe the LED’s for the status of your tubes, if the green LED is on, you are ready play music! If an LED isn’t illuminated, it means there is likely a fault with your tube and it needs to be replaced.

Dyna-70 Ultimate Upgrade, Auto Bias Printed Circuit Board MSRP(For those who desire to build and populate circuit card using their own parts;

The model AB-Q auto bias module is designed to optimize the bias for four triode or pentode output tubes in Push-Push (PP) or Parallel-Push-Pull (PPP) amplifiers that have their own negative bias supply circuit.

Suitable for class A, AB, or B tube amplifiers.

The AB-Q dynamically controls the bias in four tubes.

The module automatically optimizes the bias settings and maintains a strict symmetry of currents through both tube branches in the output stage. It will also stop any DC current flowing through the output transformers, all with the minimum of current loading on the anode of a tube. 

DC current saturates an output transformer which results in increased low frequency distortions.

The bias level is kept at the preset value irrespective of the input signal.

This module MUST use the 1:1 isolation transformer, sold separately, if the 6.3VAC filament supply is in any way referenced to ground!

– PCB dimensions are 125mm x 50mm x 15mm high / 5″ x 2″ x 0.6″ high

– negative DC bias supply between -50V to -250V

Price for one AB-Q module: US$75.00       in stock

Shipping of $11.00 for the lower 48 will be added when you click on the PayPal button.

For shipping outside the lower 48, please contact us first, thank you.

NOTE: Hardware such as spacers and screws to mount the module is NOT included.

The model AB-Qi auto bias module is designed to optimize the bias for four triode or pentode output tubes in Push-Push (PP) or Parallel-Push-Pull (PPP) amplifiers that have their own negative bias supply circuit.

Suitable for class A, AB, or B tube amplifiers.

The AB-Qi dynamically controls the bias in four tubes.

The module automatically optimizes the bias settings and maintains a strict symmetry of currents through both tube branches in the output stage. It will also stop any DC current flowing through the output transformers, all with the minimum of current loading on the anode of a tube. 

DC current saturates an output transformer which results in increased low frequency distortions.

The bias level is kept at the preset value irrespective of the input signal.

This module has a 1:1 12V isolation transformer for the 6.3VAC supply, making it suitable to use in an amp where the 6.3VAC filament supply is referenced to ground!

– PCB dimensions are 125mm x 50mm x 15mm high / 5″ x 2″ x 0.6″ high

– isolated 6.3VAC for use with ground referenced 6.3VAC filament supply

– negative DC bias supply between -50V to -250V

Price for one AB-Qi module: US$80.00       in stock

Shipping of $11.00 for the lower 48 will be added when you click on the PayPal button.

For shipping outside the lower 48, please contact us first, thank you.

NOTE: Hardware such as spacers and screws to mount the module is NOT included.

The model AB-Di auto bias module is designed to optimize the bias for two triode or pentode output tubes in Push-Push (PP) amplifiers that have their own negative bias supply circuit.

Suitable for class A, AB, or B tube amplifiers.

The AB-Di dynamically controls the bias in two tubes.

The module automatically optimizes the bias settings and maintains a strict symmetry of currents through both tube branches in the output stage. It will also stop any DC current flowing through the output transformers, all with the minimum of current loading on the anode of a tube. 

DC current saturates an output transformer which results in increased low frequency distortions.

The bias level is kept at the preset value irrespective of the input signal.

This module may be powered by the filament supply of an amp, with a range from 6.3V to 12.6V AC.

and comes with its own built in isolation transformer where the 6.3VAC filament supply is referenced to ground.

– PCB dimensions are 65mm x 57mm / 2.55″ x 2.25″

– Suitable for single ended amps

– power supply requirement is 6.3 to 12VAC

– negative DC bias supply between -50V to -250V

Price for one AB-Di module: US$75.00     in stock

Shipping of $11.00 for the lower 48 will be added when you click on the PayPal button.

For shipping outside the lower 48, please contact us first, thank you.

NOTE: Hardware such as spacers and screws to mount the module is NOT included.

The model AB-Oi auto bias module is designed to optimize the bias for eight triode or pentode output tubes in Push-Push (PP) or Parallel-Push-Pull (PPP) amplifiers that have their own negative bias supply circuit.

Suitable for class A, AB, or B tube amplifiers.

The AB-Oi dynamically controls the bias in eight tubes.

The module automatically optimizes the bias settings and maintains a strict symmetry of currents through both tube branches in the output stage. It will also stop any DC current flowing through the output transformers, all with the minimum of current loading on the anode of a tube. 

DC current saturates an output transformer which results in increased low frequency distortions.

The bias level is kept at the preset value irrespective of the input signal.

This module may be powered by the filament supply of an amp, with a range from 6.3V to 12.6VAC

– PCB dimensions are 100mm x 100mm / 4″ x 4″”

– Suitable for Cathode Feedback amps

– power supply requirement is 6.3 to 12VAC

– negative DC bias supply between -50V to -250V

Price for one AB-Oi module: US$80.00       in stock

Shipping of $11.00 for the lower 48 will be added when you click on the PayPal button.

For shipping outside the lower 48, please contact us first, thank you.

NOTE: Hardware such as spacers and screws to mount the module is NOT included.

The model AB-Qi-ST70-ST120 auto bias module is designed to fit the Dynaco ST70 chassis and can be used in an original Dynaco ST-70 upgraded with a VTA driver circuit or the new generation Bob Latino ST-70 and ST-120 stereo power amps.

It comes with a 1:1 isolation transformer so that the module can safely use one of the PA-060 power transformer 6.3VAC filament windings for its power.

The AB-Qi-ST70-ST120 dynamically controls the bias in four tubes.

The module automatically optimizes the bias settings and maintains a strict symmetry of currents through both tube branches in the output stage. It will also stop any DC current flowing through the output transformers, all with the minimum of current loading on the anode of a tube. 

DC current saturates an output transformer which results in increased low frequency distortions.

The bias level is kept at the preset value irrespective of the input signal.

This module has a 1:1 12V isolation transformer for the 6.3VAC supply, making it suitable to use in an amp where the 6.3VAC filament supply is referenced to ground!

– PCB dimensions are 100mm x 57mm / 4″ x 2.25″

– Suitable for Cathode Feedback amps

– power supply requirement is 6.3VAC from one of the PA-060 filament windings

– negative DC bias supply between -55V to -90V

Price for one AB-Qi-ST70/ST120 module: US$85.00       in stock

Shipping of $11.00 for the lower 48 will be added when you click on the PayPal button.

For shipping outside the lower 48, please contact us first, thank you.

NOTE: Hardware such as spacers and screws to mount the module is NOT included.

The model AB-Qi-M125 auto bias module is designed to fit the Bob Latino M125 mono block power amp. This module is also suitable for the Dynaco MK3 mono block.

It comes with a 1:1 isolation transformer so that the module can safely use one of the PA-060 power transformer 6.3VAC filament windings for its power.

The AB-Qi-M125 dynamically controls the bias in four tubes for the M125 or two tubes for the Dynaco MK3.

The module automatically optimizes the bias settings and maintains a strict symmetry of currents through both tube branches in the output stage. It will also stop any DC current flowing through the output transformers, all with the minimum of current loading on the anode of a tube. 

DC current saturates an output transformer which results in increased low frequency distortions.

The bias level is kept at the preset value irrespective of the input signal.

This module has a 1:1 12V isolation transformer for the 6.3VAC supply, making it suitable to use in an amp where the 6.3VAC filament supply is referenced to ground!

– PCB dimensions are 100mm x 57mm / 4″ x 2.25″

– Suitable for Cathode Feedback amps

– power supply requirement is 6.3VAC from one of the PA-060 filament windings

– negative DC bias supply between -55V to -90V

Price for one AB-Qi-M125 module: US$85.00       in stock

Shipping of $11.00 for the lower 48 will be added when you click on the PayPal button.

For shipping outside the lower 48, please contact us first, thank you.

NOTE: The price of $85.00 DOES NOT inlcude any mounting hardware, the two extra coupling capacitors and two resistors required for the M125. These are not required for the Dynaco MK3!

The model AB-Di MKIV auto bias module is designed to optimize the bias for two triode or pentode output tubes in Push-Push (PP) amplifiers that have their own negative bias supply circuit.

The pcb has been designed tro suit the Dynaco MKIV mono block

The AB-Di MKIV dynamically controls the bias in two tubes.

The module automatically optimizes the bias settings and maintains a strict symmetry of currents through both tube branches in the output stage. It will also stop any DC current flowing through the output transformers, all with the minimum of current loading on the anode of a tube. 

DC current saturates an output transformer which results in increased low frequency distortions.

The bias level is kept at the preset value irrespective of the input signal.

This module may be powered by the filament supply of an amp, with a range from 6.3V to 12.6V AC.

and comes with its own built in isolation transformer where the 6.3VAC filament supply is referenced to ground.

– PCB dimensions are 65mm x 57mm / 2.55″ x 2.25″

– Suitable for single ended amps

– power supply requirement is 6.3 to 12VAC

– negative DC bias supply between -50V to -250V

Price for one AB-Di MKIV module: US$70.00     on order

Shipping of $11.00 for the lower 48 will be added when you click on the PayPal button.

For shipping outside the lower 48, please contact us first, thank you.

NOTE: Hardware such as spacers and screws to mount the module is NOT included.

The model AB-D-MKIII auto bias module is designed to fit the Dynaco MKIII amp chassis.

It optimizes the bias for two triode or pentode output tubes in Push-Push (PP) amplifiers that have their own negative bias supply circuit.

Suitable for class A, AB, or B tube amplifiers.

The AB-D-MKIII dynamically controls the bias in two tubes.

The module automatically optimizes the bias settings and maintains a strict symmetry of currents through both tube branches in the output stage. It will also stop any DC current flowing through the output transformers, all with the minimum of current loading on the anode of a tube. 

DC current saturates an output transformer which results in increased low frequency distortions.

The bias level is kept at the preset value irrespective of the input signal.

This module may be powered by the filament supply of an amp, with a range from 6.3V to 12.6V AC.

It is important to note that the AB-D-MKIII MUST use an isolation transformer, as the Dynaco MKIII’s filament supply is referenced to ground. We sell this isolation transformer as a separate unit, click here and scroll down.

– PCB dimensions are 65mm x 57mm / 2.55″ x 2.25″

– Suitable for single ended amps

– power supply requirement is 6.3 to 12VAC

– negative DC bias supply between -70V to -120V

Price for one AB-D-MKIII module: US$62.00      in stock

Shipping of $11.00 for the lower 48 will be added when you click on the PayPal button.

For shipping outside the lower 48, please contact us first, thank you.

NOTE: Hardware such as spacers and screws to mount the module is NOT included.

The model ABS-Qi+ auto bias module is designed to optimize the bias for four triode or pentode output tubes in Push-Push (PP) or Parallel-Push-Pull (PPP) amplifiers that DO NOT have their own negative bias supply circuit.

Suitable for class A, AB, or B tube amplifiers.

The ABS-Qi+ dynamically controls the bias in four tubes.

The module automatically optimizes the bias settings and maintains a strict symmetry of currents through both tube branches in the output stage. It will also stop any DC current flowing through the output transformers, all with the minimum of current loading on the anode of a tube. 

DC current saturates an output transformer which results in increased low frequency distortions.

The bias level is kept at the preset value irrespective of the input signal.

This module is completely autonomous as it has its own bias and 6.3VAC power supplies.

The ABS-Qi+ will operate with the filament supply in your amp reference to ground, such as a center tap, since it comes with it own power transformer!

– PCB dimensions are 100mm x 80mm x 25mm high / 4″ x 3.15″ x 1″ high

– completely autonomous, comes with its own bias and operating supplies!

Price for one ABS-Qi+ module: US$100.00       in stock

Shipping of $11.00 for the lower 48 will be added when you click on the PayPal button.

For shipping outside the lower 48, please contact us first, thank you.

NOTE: Hardware such as spacers and screws to mount the module is NOT included.

The model AB-2 auto bias module is a first generation design and is designed to optimize the bias for two triode or pentode output tubes for Push Pull (PP) or Single Ended amplifiers that have their own negative bias supply circuit.

The AB-2 provides an ERROR output for an external safety circuit, via a TTL compatible open collector output. LED’s are used for start up, fault and ‘bias reached’ conditions.

Suitable for class A, AB, or B tube amplifiers.

Bias is controlled by maintaining a constant voltage drop on the output tube cathode resistors, irresepective of driving signal.

The module automatically optimizes the bias settings and maintains a strict symmetry of currents through both tube in the output stage. It will also stop any DC current flowing through the output transformers, all with the minimum of current loading on the anode of a tube. 

DC current saturates an output transformer which results in increased low frequency distortions.

The bias level is kept at the preset value irrespective of the input signal.

This module may be powered by the filament supply of an amp, with a range from 6.3V to 12.6V, DC or AC.

It is important to note that the AB-2 WILL NOT operate if the filament supply has any reference to ground, such as a center tap.

For that scenario, use the auto bias module models ABF-Q or ABS-Q+ or provide your own small power transformer of around 2VA with, for example, a 9V secondary.

– PCB dimensions are 74mm x 42mm high / 3″ x 1.65″

– Suitable for Single Ended Amps

– power supply requirement is 6.3 to 12VAC

– negative DC bias supply between -50V to -250V

Price for one AB-2 module: US$85.00       in stock

Shipping of $11.00 for the lower 48 will be added when you click on the PayPal button.

For shipping outside the lower 48, please contact us first, thank you.

NOTE: Hardware such as spacers and screws to mount the module is NOT included.

The model AB-4 auto bias module is a first generation design and is designed to optimize the bias for four triode or pentode output tubes for Push Pull (PP) that have their own negative bias supply circuit.

The AB-4 provides an ERROR output for an external safety circuit, via a TTL compatible open collector output. LED’s are used for start up, fault and ‘bias reached’ conditions.

Suitable for class A, AB, or B tube amplifiers.

Bias is controlled by maintaining a constant voltage drop on the output tube cathode resistors, irresepective of driving signal.

The module automatically optimizes the bias settings and maintains a strict symmetry of currents through all tubes in the output stage. It will also stop any DC current flowing through the output transformers, all with the minimum of current loading on the anode of a tube. 

DC current saturates an output transformer which results in increased low frequency distortions.

The bias level is kept at the preset value irrespective of the input signal.

This module may be powered by the filament supply of an amp, with a range from 6.3V to 12.6V, DC or AC.

It is important to note that the AB-4 WILL NOT operate if the filament supply has any reference to ground, such as a center tap.

For that scenario, use the auto bias module models ABF-Q or ABS-Q+ or provide your own small power transformer of around 2VA with, for example, a 9V secondary.

– PCB dimensions are 74mm x 42mm high / 3″ x 1.65″

– power supply requirement is 6.3 to 12VAC

– negative DC bias supply between -50V to -250V

Price for one AB-4 module: US$96.00       in stock

Shipping of $11.00 for the lower 48 will be added when you click on the PayPal button.

For shipping outside the lower 48, please contact us first, thank you.

NOTE: Hardware such as spacers and screws to mount the module is NOT included.

We can also offer to do the remote LED modifcation for the AB-Q, AB-Qi, AD-Di, AB-Oi, AB-Qi-ST70/ST120 & AB-Qi-M125 modules.

This mod replaces the OEM SMD blue LED’s and replace them with remote 4mm GREEN LED’s.

We can add these remote LED’s either side of the pcb, the photo shows top side.

Standard wire length is 5″, if you need a different length, you will need to let us know.

With us doing this mod, it will not affect the warranty of the modules.

Cost for this mod is US$45.00, which includes all parts and labor.

We now offer a PCB assembly service where for $185 we will assemble and test your Dyna Audio/Power Supply Drive Card, saving you time and trouble with a properly assembled and tested Circuit Card Assembly.

Dyna-70 / -120 Ultimate Upgrade Kit / For Do-It-Yourself (DIY) Hobbyists
Our kits feature all through-hole components; the electronic circuits are built on high-quality, etched 2-layer FR-4 Copper faced Printed Circuit Boards with plated through holes for generous solder contact and easy soldering. The circuit boards have been designed with generous spacing between all soldered points, making assembly easy and reducing solder bridges.
We use quality, trusted name brand components from manufacturers such as Nichicon, United ChemCon, Panasonic, Wima, Solen, Audyn and other name brand components. We source our components from Mouser, Digi-Key, Newark, and other reputable U.S. suppliers; you can trust all components are genuine and not cheap counterfeit parts.

Kit construction has four steps:
1. Downloading & printing the latest version of the Assembly Manual
2. Assembling and soldering the PC board
3. Wiring the Chassis
4. Mounting the new PC board and completing wiring & final assembly

Note: Kits do not include vacuum tubes or the required higher output Power Supply transformer. See our website, we stock and sell vacuum tubes and the improved transformer separately

Upgrade Your Dyna-70 Upgrade Circuit Card for Improved Sound Quality
For All Automatic & Manual Bias Dyna-70 Systems
A new product for 2024, yet one that is hard to explain why you need it… we will try to keep it simple. Most audio designs that use an LM-334 Regulator, implement it in an “uncompensated” manner. Meaning that as your amplifier operates and slowly heats up, the audio signal can be distorted by this heating, which is a result of using a silicon-based solid-state component.

Since silicon devices are known to have this property, one must cool the silicon to counter the effects of this phenomenon or, compensate for it as it warms. A good example is the application of heat sinks, cooling fans, and even water cooling for high-performance gaming computer processors. The original LM-334 was top mounted in the Dyna-70 PCB where the vacuum tubes heated the -334. We moved the -334 to an underside (bottom side of the Dyna-70 circuit board) location to shield the part from heat, which worked “OK” as a temporary fix (ref. ECN001 in “Documents”), but for us it was not good enough. We knew the best solution was a thermally compensated -334.

If you have a Dyna-70 Ultimate Upgrade system that was built in the past 5-6 years, odds are you need the thermally compensated SMT-334, since we just introduced these in late fall of 2023 this pretty much means everyone who has built a Dyna-70 Ultimate Upgrade kit. What if you do not upgrade? You will miss the ideal stereo image and channel separation caused by the warming, and the stereo image will “wander” and not be distinct or focused after operating for a few hours. We have in-stock and set of two is only $30.00

Introducing our new Negative Feedback Selector (NFS) upgrade for Dyna-70 and Dyna-120 Amplifiers. Questions such as: “What is Negative Feedback?” and “Why do I need a Negative Feedback Selector?” often follow. Therefore, some background on what Negative Feedback (NFB) is, how it’s used, and why you should consider this upgrade.

The Dynaco ST-70 is designed with 4-, 8- & 16-Ohm speaker outputs. As with most audio amplifiers, the ST-70 uses a signal called Negative Feedback (NFB), taken from the audio output, which is then fed back into the audio input circuit of each channel to correct for distortion. NFB is a “control loop,” and is always working to correct the audio signal, to minimize distortion.

A compromise Dynaco made was to use the 16-Ohm output for the NFB signal for all speaker impedances. This is fine if one is using 16-Ohm speakers, but what if you are using 4- or 8- ohm speakers? The 16-Ohm NFB circuit is not optimized for the lower speaker impedances, meaning the distortion products are not properly compensated for, which can lead to distortion in the amplifier and in extreme cases can impact overall frequency response and bandwidth performance.

The NFB Selector corrects this by using a correction circuit that has all 3 speaker impedances available to properly compensate for NFB, providing the proper feedback signal correction for any 4-, 8-, or 16-Ohm speaker. One simply sets the selector for the desired speaker impedance and your Dyna Ultimate Amplifier will provide the lowest distortion signal correction for the speaker impedance used. It’s simple, easy, safe, can be done in a matter of minutes, and does not require one to work inside a powered amplifier; installation and NFB change can be made with no power to the amplifier.

Does it matter? / Does it really work? We promise, if you are using the 16-Ohm Output from the A-470 as your NFB signal source in your Dyna-70, you will hear & sense an immediate improvement in sound output if you install the NFS system in your amplifier and your audio system speakers are 4-or 8-Ohms.

If you use a 16-Ohm speaker system, continue to use the 16-Ohm terminal for both NFB and to drive your 16-Ohm speakers. However, remember to use the NFS to select the proper NFB signal should you change from 16-Ohm speakers and set for the speaker impedance you will be using, whether 4- or 8-Ohms.

The NFS upgrade kit comes with 2 PCB’s for left & right channels, as well as all components to assemble and install the NFS. We have the NFS upgrade kit in stock and ready for installation in your Dyna amplifier- only $43.00 + S&H.

NOTE: The NFS Upgrade Kit is not compatible with a standard Dynaco ST-70. It is designed for use with the Dyna-70 & Dyna-120 Ultimate audio systems. It is not compatible with other 3rd Party audio-upgrade circuit cards.

Dyna-70 Power Transformer (PA-060-70):
Construction: Features a taller lamination stack for cooler operation and reduced noise compared to original PA-060 models. The PA-060-70 features an increased thickness of the lamination stack and the lamination the plates are now made from M6 steel and feature a copper Flux band around the transformer for reduced EMI/RFI noise and improved efficiency.
Specifications: Operates at 120 VAC @ 50/60 Hz, with a high voltage B+ 720 VCT (360-0-360 @ 300 mA), a negative 55V bias output, dual 6.3 VAC @ 5A heater filament outputs, and a 5.0 VAC @ 4A rectifier output.
Compatibility: Direct drop-in replacement for Dynaco-ST-70 amplifiers, and required for the Dyna-70 Ultimate Upgrade, providing reliable power for 6SN7 heater filaments.

Dyna-120 Power Transformer (PA-060-120):
Construction: Heavier and taller than the PA-060-70, with increased thickness of the lamination plates, the plates are now made from M6 steel and feature a copper Flux band around the transformer for reduced EMI/RFI noise and improved efficiency.
Specifications: Operates at 120 VAC @ 50/60 Hz, with a high voltage B+ 820 VCT (410-0-410 @ 450 mA), a negative 55V bias output, dual 6.3 VAC @ 6A heater filament outputs, and a 5.0 VAC @ 5A rectifier output.
Compatibility: Designed for the Dyna-120 Ultimate Upgrade, supporting more powerful 6550/KT-88 tubes and delivering 60 watts per channel.

Introducing Tube Pin Terminal Blocks, new at Miller Audio. We developed these jointly with Danny Richie & Hobbs Ray @ GR Research in Iowa Park, TX ( GR Research.com ) for their line of stereo speakers. These are designed for GR Research speaker owners who desire a common tube pin interface from amplifier-to-speaker, with a finished interface that looks like it was designed and integrated at the factory- just as Dynaco might have designed it. Note the 16-Ohm transformer output is not used with this terminal block. To learn more about this tube pin product development, see this YouTube video: https://www.youtube.com/watch?v=MN-nyEhYWmk

This Terminal Block will fit a Dynaco ST-70, SCA-35, and Mark II, III & IV mono-block amplifiers; as well as Marantz 8B & Harmon Kardon Citation II amplifiers. Comes with all hardware depicted and includes fasteners to mount to the amplifier, $110.00/set.

The High-Performance Terminal Block is derived from our tube pin terminal block development with GR Research. We took a different path for the interconnects, since most Miller Audio customers are not using tube pin connectors to interface with their amplifier. We used the same 3-D printed terminal block for the tube pin connector project, then insert a Made-in-the-U.S.A., 5-Way binding post made from Gold Plated, Copper-Tellurium. These binding posts have no ferrous parts and are as low-mass as possible. We found the supplied binding post retaining nut and washer were made from ferrous materials and magnetic. We replaced with a Silicon-Bronze lock washer and a brass nut, removing all ferrous parts in the binding post and audio signal path, only $135.00/set.

(Note: The 16-Ohm transformer output is not used with this terminal block)

We use two types of Slide Power Switches, both featuring Silver-Plated, Double Pole/Double Throw (DP/DT) contacts for enhanced reliability and to extend switch life. The silver-colored switch, made by Switchcraft, is rated 5A @ 125VAC and is designed for use in the Dyna-70, and uses a 3A Fuse.  Given the Dyna-70 usually only operates around 2.5 Amps, this switch should last the life of the amplifier. The Black Power Switch is for the Dyna-120 and is rated at 12 Amps @ 125VAC and uses a 5A Fuse.

Panel mount fuse holder for 1-1/4″ x 1/4″ AGC/3AG fuses. Fuse holders have Faston- style terminals that can also be used as solder contacts and rated for 15A @ 120VAC. Hole size is approx. 5/8″ (14.7mm); comes with locking nut but does not include a fuse!

The fuse holder fits both the Dyna-70 & -120 amplifiers and fits both Black & Stainless-Steel chassis, $7.00.
(Note: For the Dyna-70 use a 3 Amp fuse; for the Dyna-120 use a 5 Amp fuse)

This socket mates to a IEC C14 male power plug and is rated for 10/15 Amps @ 125/250VAC; comes with Black Oxide Fasteners & Kep Nuts;

These are Black with a molded finish texture that matches the powder coat texture on the Black Chassis. Feet are ½ inch (13mm) in height and 1.50 inches (38mm) in diameter; comes with 4 Fasteners & Kep Nuts; $11.00/set.

We buy transformer covers in bulk so that we can provide various finishes and appearance packages our customer’s demand. Today, no one wants a 1950’s amplifier in a modern-day Man Cave or with modern speakers.
Note: These plated covers are not “show” finished. Show finishes involve hours of hand polishing and meticulous attention to detail to achieve a mirror finish. Yes, they look great when new- but how do they age over time? Customers comment that a polished show finish is too “bright”, and draws your attention to the amplifier and not the music.

Copper Transformer Covers & Face Plate- $220.00
Nickel Transformer Covers & Face Plate- $225.00
(Note: For Transformer Covers used on the Stainless-Steel Chassis, we recommend use of Silver Cadmium Plated fasteners. For Covers on the Black Chassis, we recommend Black Oxide fasteners).

As a lower-cost option to our plated covers, we also provide Matte Black Transformer Covers powder coated with the powder coat used on the Black chassis; this provides the ideal color base for our “Black-Out” look that many like.
Matte Black Powder Coated Transformer Covers, set of 5- $120.00

(Note: For Transformer Covers used on the Stainless-Steel Chassis, we recommend use of Silver Cadmium Plate fasteners. For Covers on the Black Chassis, we recommend Black Oxide fasteners).

We now offer a PCB assembly service where for $150 we will assemble and test your Dyna Audio/Power Supply Drive Card, saving you time and trouble with a properly assembled and tested Circuit Card Assembly.

Dyna-70 / -120 Ultimate Upgrade Kit / For Do-It-Yourself (DIY) Hobbyists
Our kits feature all through-hole components; the electronic circuits are built on high-quality, etched 2-layer FR-4 Copper faced Printed Circuit Boards with plated through holes for generous solder contact and easy soldering. The circuit boards have been designed with generous spacing between all soldered points, making assembly easy and reducing solder bridges.
We use quality, trusted name brand components from manufacturers such as Nichicon, United ChemCon, Panasonic, Wima, Solen, Audyn and other name brand components. We source our components from Mouser, Digi-Key, Newark, and other reputable U.S. suppliers; you can trust all components are genuine and not cheap counterfeit parts.

Kit construction has four steps:
1. Downloading & printing the latest version of the Assembly Manual
2. Assembling and soldering the PC board
3. Wiring the Chassis
4. Mounting the new PC board and completing wiring & final assembly

Note: Kits do not include vacuum tubes or the required higher output Power Supply transformer. See our website, we stock and sell vacuum tubes and the improved transformer separately

The Face Plate & Logo are designed and manufactured in North America. Customer response to this new faceplate has been great.  We have in-stock & ready to ship in your choice of Silver or Black.

Introducing our new Aluminum Face Plate, available in a natural Aluminum Silver or Black anodized finish with an optional logo in contrasting White or Black font featuring a raised embossed finish. A simple, yet clean and elegant look, these Face Plates were designed for our new Black chassis but as the photo’s illustrate, they also look great on a Stainless Steel or an original Nickel Plated chassis too.

Our Face Plate is custom machined from 6100 series Aluminum sheet that is 0.125 inches (~ 3 mm) thick and features pre-drilled holes in the Face Plate for female RCA panel jacks, which are now moved outward from the original center location of the chassis face to the center-point of the front octal socket locations. This eliminates the need to upgrade the RCA jack panel Dynaco originally used at the center of the original chassis face, providing ample space for any audio signal cable with large RCA fittings.

The Face Plate & Logo are designed and manufactured in North America. Customer response to this new faceplate has been great.  We have in-stock & ready to ship in your choice of Silver or Black.

NOTE: Please specify if you want a logo or “logo-delete” when ordering. Logo’s are installed upon order and are difficult to apply correctly. If installed incorrectly, to remove logo will ruin the anodized finish!  Let us do the hard work of applying the Logo and take that risk for you.

• Construction: 12 AWG/3-Conductor/Stranded

• Diameter: Approx. 0.75 inches / 19 mm

• Length:  6.5 Feet / 2.0 Meter

• Sheathing: Polyethylene Expanded Braid over Polyethylene Sheath

• Weight:  Approximately 3 lbs. / 1.4 Kg

Our new IEC Power Cable features 3, stranded 12 AWG Copper conductors, sheathed in a flexible Black Polyethylene jacket and braid, with easy to grip large, machined billet Aluminum fittings. This power cable was designed to enhance & pair with our new Black ST-70 Chassis, however, they complement any Silver, Stainless-Steel, Black or Gray audio equipment. Better yet, they won’t break the bank.

You can use this power cable with any IEC socket equipped audio or computer product such as an amplifier, pre-amplifier, Turn-Table, CD-Player, DAC, Power Supply / Power Supply Filter, etc. We offer these cables only in one length @ 6.5 FT (approx. 80 inches or 2 Meters).

These cables are backed with a 5-Year Warranty against defects in manufacture or materials. Buy with confidence and knowledge that your power cable will last much longer than most of your vacuum tubes!

Introducing our new Black powder coated, stamped chassis manufactured with an IEC socket. For audiophiles who use large Power Supply Cables or have already invested in high-end IEC Power Cables for their audio equipment, look no further. Now you can finally use those IEC cables on your ST-70 with our new chassis.

The chassis, bottom cover and optional tube cage are all designed and manufactured in the U.S.A.

Includes Bottom Cover and Black Oxide finished fasteners.

NOTE: New production ST-70 Tube Cages & Chassis bottom covers are available separately in Black or Brown. Contact us for more information to order.

Annoucing an “upgrade” to our Upgrade…

The Manual Bias system in our Dyna-70 Ultimate Upgrade Manual Bias ST-70 Amplifier has been upgraded with a new part. We introduced the Manual Bias system about 6 years ago using a single-turn Bourns Trimpot potentiometer for Bias adjustment in the Dyna-70 Ultimate Upgrade audio system. Those familiar with the Manual Bias Dyna-70 know we use 4 of these square body potentiometers on each Manual Bias Dyna-70 circuit card.

However, a drawback to using a single-turn potentiometer is the Trim pot is quite sensitive, and it‘s easy to under or overshoot the ideal Bias setting when adjusting the pot. We decided to change to a pot that was more user-friendly, enabling users to more precisely set their Bias values, while avoiding changes to the Manual Bias circuit card design.

We found a perfect replacement, also made by Bourns, but in a 4-Turn version that has a round body and is not as sensitive to adjust as the 1-Turn pot.  Now you can easily dial in the Bias set value you want.

This new round 4-turn pot is a drop-in replacement to the single-turn pot now in your Dyna-70 Ultimate Upgrade Manual Bias system.  We will phase out the square, single-turn pot and use the new round, 4-turn pots in all Dyna-70 Upgrade audio kits, all service and repair activities, and in all MALLC new Amplifier custom builds.

NOTE: This upgrade is applicable to the Manual Bias Dyna-70 Ultimate Upgrade Audio System; it is not applicable to the Automatic Bias models.

Triad C-24X DC Choke / Smoothing Filter Specifications:

Low-Cost alternative to the C-354; performs well in the Dyna Ultimate Upgrade;

Inductance*: 1.00 Henry

Max. Current Capacity: 240mA DC

Resistance: 50 ohm

Max. Operating Voltage: 400 vdc

Specification Tolerance: -20%/+50%*

Price: $23.00

Original Dynaco C-354 DC Choke / Smoothing Filter Specifications:

Features enclosed bell ends for lower RF/EMI noise;

Inductance: 1.75 Henry

Max. Current Capacity: 200mA DC

Resistance: 62 ohm

Max. Operating Voltage: 400 vdc

Specification Tolerance: 10% +/-

Price: $44.00

Note 1: Both Chokes are drop-in replacements for Dynaco ST-70, Mark III & Mark IV mono block amplifiers.

Note 2: The Dyna-70 requires one Choke; The Dyna-120 requires two Chokes.

One result of the listening tests conducted @ GR Research with our Dyna-70 amplifier was to eliminate all ferrous electromagnetic materials in our audio output chain. This small, yet impactful change can improve high frequency response in most audio systems. The only ferrous parts we have in our audio output chain were the steel, Cadmium plated terminal screws in the terminal block, which come this way from the manufacturer. The metal terminal in the block is made from Tin-Plated ½ hard Brass, making it easy to solder the Transformer output leads to the terminal end.
We now offer our standard terminal block with solid copper screws and washers, which we now call the “Improved” Standard Terminal Block.

We offer in two configurations:
⦁ The Improved Standard Terminal Block with Copper Screws & Washers for $50.00.

⦁ If you already have our Standard Terminal Block, you can purchase a Copper Screw & Washer kit for $20.00 and upgrade your Standard Terminal Block to the “Improved” configuration.

Note: Prices do not included Shipping & Handling

Tough Nut Isolation Cones from Miller Audio are precision-engineered vibration control “feet” designed to reduce unwanted resonance and improve the performance of high-end audio equipment. Developed using the same proven elastomeric isolation technology found in Tough Nut’s Turntable Isolation Platform, these isolation cones effectively damp vibro-acoustic energy transferred between your component and its supporting surface. The result is improved clarity, tighter bass response, better imaging, and a more focused soundstage compared to conventional “hockey puck” style isolators.

The Small Imperial version measures 1″ in diameter x 1-1/2″ in height and uses a standard 1/4″-20 thread. Each set of four cones supports up to 80 lbs and includes four matching threaded barrels. These isolation cones are ideal for use under turntables, CD players, DACs, preamps, amplifiers, isolation platforms, and speakers within the rated load capacity.

Tough Nut Small Isolation Cones are available in four finishes: Brushed Stainless Steel ($149.00 USD), Black Powder Coat ($156.00 USD), Copper ($164.00 USD), and Polished Stainless Steel ($172.00 USD). Each finish maintains the same load rating and performance characteristics.

For audiophiles seeking an affordable yet highly effective solution for audio vibration control, Tough Nut Isolation Cones deliver measurable damping performance and refined sonic improvements in a compact, precision-machined design. Larger isolation models for heavier loudspeakers are currently in development.

Pavel Kostas, owner of Audio Amp in the Czech Republic and the Miller Audio team have always been big fans of the Dynaco ST-35 tube amplifier, and we both love the sound of EL-84 / 6BQ5 tubes. In 2024, working with Dave Gillespie of Dave Gillespie Designs and Chris Keller of Retropro Audio, we collaborated to revive production of the Dynaco ST-35 amplifier. Our plans included making a new chassis with a bit more interior volume and we planned all along to have a fully automatic bias system. We have in stock and ready to ship. Note: The ST-35 Auto Bias Module will not fit in an original Dynaco ST-35 Chassis!

We’ve sold a lot of these for Dynaco tube amplifier upgrades; in fact, this part is our largest selling single item. We had feedback from customers requesting marking of the Speaker Impedance value on the terminal blocks. Now for 2025, you can purchase either marked or unmarked terminal blocks and at two price points

One of the reasons that our Tough Nut Isolation Cones work so well, is that the rubber incorporates some flex. This feature provides give, or a degree of acceptance vs a rigid surface experiencing harsher impact from airborne or seismic vibration.

The same fundamental principle occurs with a ship adrift at sea, it could remain afloat for years but the minute it runs aground, the energy from the oceans waves will ultimately destroy the vessel.

That said, when our Tough Nut Isolation Cones are aplied to taller floor standing speakers, the degree of flex or movement needs to be managed, and this is where the Tough Nut Isolation Cylinders come into play and can take over for our Isolation Cones.

Our Tough Nut Isolation Cylinders provide a broader foot print, supporting taller speakers more affectively while performing similarly to our Isolation Cones. An additional benefit of the Isolation Cylinders, is that their load capacity is greater than the Isolation Cones. So while taller speakers are generally heavier, the Isolation Cylinders can manage the added weight and the vibration as well.

LARGE ISOLATION CYLINDERS standard set of 4
2″ Dia. x 3/4″H rubber cylinders, 2″ Dia. x 1/2″H brushed stainless steel barrels, rubber washers & flange nuts
Thread size: 3/8 x 16
Max weight for set of 4 600 lbs (272 kg)
Price: $198.00 USD

LARGE ISOLATION CYLINDERS metric set of 4 –
50mm Dia. x 19mm H rubber cylinders, 50mm Dia. x 13mm H brushed stainless steel barrels, rubber washers & flange nuts
Thread size: M10
Max weight for set of 4: 272 kg (600 lbs)
Price: $198.00 USD

MEDIUM ISOLATION CYLINDERS standard set of 4
1-1/2″ Dia. x 3/4″H rubber cylinders. 1-3/4″ Dia. x 1/2″H brushed stainless steel barrel, rubber washers & flange nuts
Thread size:5/16 x 18
Max weight for set of 4: 350 lbs (158 kg)
Price: $170.00 USD

MEDIUM ISOLATION CYLINDERS metric set of 4
38mm Dia. x 19mm H rubber cylinders, 45mm Dia. x 13mm H brushed stainless steel barrels, rubber washers & flange nuts
Thread size: M8
Max weight for set of 4 158 kg (350 lbs)
Price: $170.00 USD

SMALL ISOLATION CYLINDERS standard set of 4
1″ Dia. x 1/2″H rubber cylinders. 1 Dia. x 1/2″H brushed stainless steel barrels, rubber washers & flange nuts
Thread size: 1/4 X 20
Max weight for set of 4: 250 lbs (114 kg)
Price: $138.00 USD

SMALL ISOLATION CYLINDERS metric set of 4
25mm Dia. x 13mm H rubber cylinders, 25mm Dia. x 13mm H brushed stainless steel barrels, rubber washers & flange nuts
Thread size: M6
Max weight for set of 4 114kg (250 lbs)
Price: $138.00 USD