Outboard audio power supply for Studer A80 by SEPEA Audio
Separated power supply for A80 audio circuits. The Studer A80R can be said was my first Master recorder, and it has been used until now. After many improvements over the years, it has also become a platform for me to verify the technology of tape recorders. The A80 series transport mechanism is solid and the design is completely modular. In addition to the simple operation, it is very convenient to organize, modify and repair the machine. The only drawback is that the size and weight is not negligible. As it was designed in the 70s, it can be overcome today. But the well tuned and upgraded A80 can be still successfuly compared to any modern system.
My Studer A80R
I went all the way trying Repro/Record cards, Stabilizer card, Repro only transport, and finally Mk.1 headblock a while ago. I have probably tried all the parts that A80 can accomodate. The only thing I haven’t tried was the power supply. One year ago, I have discussed the possibility to design outboard power supply of A80 audio circuits with Peter Sedlak from SEPEA audio company.
Original Studer A80 Power transformer provides two lines of 16Vac for the Stabilizer card, and then the Stabilizer card provides +/-12Vdc for the audio circuit. Since the audio circuit of the A80 is completely modular, it is very easy to find relevant pinout. You can easily disconnect the 16Vac from the main power supply of the A80, and provide +/-12Vdc externally for the audio circuits. The only question is whether you can deliver better power supply than original without affecting the S/N ratio (it is good).
For this reason, SEPEA audio based their design on their original modern Stabilizer Card, and made an Outboard Audio Power Supply for A80, A80R/RC/A81, or B62. You only need to remove the original Stabilizer Card, then insert the SEPEA stabilizer card to corresponding slot (according to recorder model). No modification is required at all, so it can be restored to the original stabilizer at any time.
Due to the COVID-19 pandemia in the first half of the year, I have received the prototype of SEPEA power supply only a month ago. After my comparison, it is indeed better sounding and there is lower background noise floor of music material. This should be the advantage to the original power supply. Since my A80R has already used the SEPEA audio Stabilizer Upgrade Card, the sound difference was not too big. But I believe that if A80 would use original Studer Stabilizer Card, the sound will be greatly improved by SEPEA audio power source upgrade.
SEPEA's Prototype just used an external 220V transformer to convert 16Vac. Of course, this will always be related to the cost price. I believe there is room for improvement. (prototype was european version only)
Posted by River