More about the Dynaco SCA-35



Gillespie Driver Boards:

The D. Gillespie Designs PC-10A replaces the obsolete, increasingly hard to find, and expensive 7199 driver tube with either a 6GH8A or 6U8A. Either of these tubes is relatively low cost and readily available. Note that this is not just a tube swap. Additional components have been added to prevent stability issues that can occur when these tubes are simply used with adapter sockets in the original PC-10  board. The PC-10A retains the original PC-10 eyelet locations for complete compatibility during installation. In fact, with the exception of a few added components, the layout is virtually the same as the PC-10.

For those who doubt the ability of the 6GH8A or 6U8A tubes to compete with the 7199, please take the time to read page 3 of the July 1990 Audio Basics Newsletter by Audio by Van Alstine. 6U8A tubes were also used by famous makers, like H.H. Scott, for exactly the same purpose (phase splitter) as they are in our PC-10A. They DO work well.

Gillespie PC-11 Phono Preamp Board

Uses (2) 12AX7 tubes. An exact fit drop in replacement for the SCA-35. Significantly improved RIAA curve accuracy. Premium capacitors and resistors. 

Gillespie SCA-35 EFB™ Power Supply Board:

Perhaps the most significant upgrade available for the SCA-35
Our new power supply / capacitor board with EFB™ converts your SCA-35 from cathode bias to a new and innovative “Enhanced Fixed Bias” mode.

Benefits of EFB™ include:

  • Increased output power (both channels driven)
  • Lower distortion
  • Lower bias current for extended tube life

View Performance Comparison Chart

Much more than just a replacement for the original twist-lock cans, our capacitor EFB™ board also replaces all the resistors and rectifier diodes associated with the power supply. Significantly larger overall capacitance and 105 degree rated components are specified that far exceed the originals in quality and reliability.

I cannot say enough about the quality and performance Dave's EFB™ and driver boards bring to the SCA-35. Dave is way ahead of the game and his offerings are simply unmatched. Visit Dave's store by clicking this link. - Thanks Dave, great stuff!

*EFB™ & "Enhanced Fixed Bias" are trademarked by D. Gillespie Designs. The ST-35 and SCA-35 EFB™ Upgrades and the Gillespie Driver Boards have been sold worldwide.

This chassis was entirely disassembled and cleaned, de-oxidized then hand polished to a great lustre. Process also stops future corrosion and rust from forming. The controls, pot and all switches were removed, cleaned, de-oxidized, tested and reused. The pilot jewel is original and is now illuminated with an LED bulb. New feet were installed. Output/input RCA panel and jacks are new gold plated pieces from Dynakit. Hum control pots were serviced and function perfectly. The ceramic and high Level phono inputs have been eliminated from this unit.

All of the tubes in the amp are new and were selected to give the best sound and performance combined with quality and longevity.

The Preamp section:
(2) 12AX7 / ECC83 Telefunken based tubes by EI of Yugoslavia. These great pre-war tubes were made in the 80's using original Telefunken machinery for Audio Research Corporation, a now defunct maker of high end amplifiers and preamplifiers. The tubes are from the estate of a former audio research employee and are very rare, I was lucky to have acquired a few. They feature smooth gray plates, top halo getters and like most European tubes such as Mullard and Telefunken these tubes flash when energized, this is normal for this tube type, due to the special filament design. These are New Old Stock High Quality Tubes, tested perfect, and they sound excellent.

The Driver / Inverter Section:
(2) Amperex 6GH8A NOS tubes made in France. These tubes occupy the position where you would normally find 7199 tubes in a stock Dynaco SCA-35. The new boards in this amp utilize this tube, they were designed especially for it. The 7199 is becoming increasingly hard to acquire and now carries inflated prices along with being outperformed by the 6GH8A as a driver tube. Famous brands like Scott and Fisher used this tube extensively. These are fantastic tubes that sound simply amazing. These tubes flash when energized due to the special filament design, they feature boxed 2 hole smooth grey plates and a top halo getter. They have copper rods and a chromed top and tested as strong as the day they were made.

The Output Section:
(4) Current Matched NOS Sovtek EL84M / 6BQ5WA High Power Tubes. The EL84M is the higher power version of the EL84 also known as the 7189A. These are great quality and powerful tubes that have a clear and creamy smooth tone. A military-spec version of the standard EL84, the EL84M boasts extended voltage tolerance, improved plate dissipation and a heavy duty robust construction making it equivalent to the 7189 tube class.

 The Faceplate and Knobs are from Dynakit. These are beautiful and have engraved ink-filled lettering. The knobs are nearly identical to the original Dynaco knobs. The rear RCA panel and jacka are from Dynakit. These eliminate the old antiquated high level and ceramic phono inputs so this unit now only accepts modern moving magnet type cartridges. 

The chassis and cover are original but have been reconditioned and look fantastic. The original power and output transformers are present and checked as good as new. These are the heart and soul of the amplifier.

This item is not covered by a warranty:

Many of the components still in this unit are original, many are new. This unit is considered as "rebuilt or reconditioned" only. This unit is classed as a modified vintage unit. We thoroughly test these types of units before offering them for sale. However due to the presence of these original parts some of which may no longer be available if a replacement is necessary we cannot offer a warranty or guarantee of any kind on units of this class.