A101 Linear hybrid amplifier module for Studer A80, B62 and mixer 189

Studer A101 Linear Hybrid Discrete Amplifier module for STUDER A80, A/B62, some A81 and mixers such as the 189. Available as DIY kit assembly to keep costs down.

The A101 is used in quite a few of the modules in Studer recorders. Why would you need to replace it? 

• The originals were epoxy encased and there is a tantalum capacitor on board that needs to be replaced. The modules were notorious for problems particularly the early H1 variety.

• Using more modern transistors with matched high gain and very low noise and using 1% low noise resistors - a slight improvement in performance may be possible.

Are all old A101 modules a problem?  No.

FAIR COMMENT.  On the market is a rival version using SMD components.  We do not consider this a  good idea for the A101 for a number of reasons. The main argument being the SMD soldering process results in undue heat fatigue and stresses particularly capacitors. Have a look at an SMD capacitor chip on an MSD boards and you will see what I mean. Why adopt mass production technology in something so elegant and simple as an A101? It doesn't make anything better except easy to manufacture.   SMD is great for modern tightly packed boards that are designed for a limited life span.  Want proof of this?  Happy to discuss with examples from tape machines.

About this kit:

•  Resistors are low noise hi stability 1% and are mounted flat not sticking up

• The capacitor is very low leakage hi stability electrolytic 105C 5000h.  Most importantly - it can be replaced in the future.

• The transistors in the standard version are BC550/560 types with low noise and medium / high gain. Transistors come from consistent gain batches.

• The transistors in the deluxe version are extremely low noise high gain made by Toshiba or Hitachi. Transistors are from consistent gain batches.

• Because the different transistors have different lead outs - the PCB for the deluxe version is slightly different - not just lead swapping.

• Header Pins are preformed (no bending required) plated copper alloy 

• Optional flexible wire lead outs are also supplied to give you greater flexibility to fit the A101 onto those boards that are quite tightly packed. Indeed we have at least options available with the hardware supplied.

• The printed circuit boards are double sided 2oz Cu HASL with mask and through plated holes. They are fully designed, not copied, by me and manufactured in Taiwan by a PCB specialist manufacturer that has been doing this for me for more than 15 years.

• Detailed instructions provided on how to assemble this relatively simple PCB.

The options:

1. Order in pairs, 4's, 9's, 16's or 24's. 

2. Standard version with high grade BC 550/560 type transistors new manufactured as specified in later Studer versions.

3. Deluxe version option sometimes available with high grade modern Toshiba / Hitachi transistors I have specifically chosen.  The PCB is slightly different but same size.  Enquire as to stock.

The A80 VU mk1 takes a lot of these modules. You will (ouch !) need 18 for each audio channel / module + 2 for the master oscillator card in the main cabinet.  If your machine has no sync then you will require 1 less.

The A80 VU mk2 - 4  Generally 4 will be required per module plus 2 on the oscillator module in the main cabinet.  (please check as often boards are mixed around over the years)

The A80 and B62 non VU models with all audio boards in the main chassis console. Generally 2 will be required per channel - 1each for Record and Playback amps.