[sdiy] Operating voltages questions about synthesizers

Roman Sowa modular at go2.pl
Mon Sep 5 11:10:37 CEST 2022

Depends what you call "sounds better".

AFAIK input voltage, 9V in original, and 12V in your case is only used 
for speaker amplifier, comparator, and pullup resistors for OTA outputs 
in the filter.
So the power amp may feel better, able to provide more power at lower 
distortion. For comparator it doesn't mean a thig. And for OTAs, well it 
changes the voltage of the output pullup resistor higher than OTA's 
power suply. That may affect how it works, introducing some nice 
distortion, increase levels, or whatever, but I'm only guessing here.

The thing is, most of the circuit is powered from internal 6V regulator 
made with TO92 transistor, so if you change input from 9 to 12V, it has 
to dissipate twice more heat than before. Probably not much anyway, but 
it's easy to check with your finger.

First thing I woudl do is to check current draw, how it changes when 
supply rises from 9 to 12. Next is to check how signal changes at OTA 


W dniu 2022-09-05 o 09:33, Logan Mitchell Sr via Synth-diy pisze:
> I am finally working on completing modifying my Electro-Harmonix EH 0400 
> mini synthesizer that I purchased brand new around 1979/1980.
> Its original factory power supply was two 9-volt batteries connected in 
> parallel with no external power supply adapter jack installed so I 
> installed one some years ago to use a 9 volt DC power supply.
> Last night I connected a 12 volt DC power supply & noticed that the 
> synthesizer sounded a little better than when operating from the 9 volt 
> battery or from the 9 volt DC power supply.
> I'm thinking about adding a 7812 or 7815 voltage regulator circuit to 
> connect to the power connection of this synthesizer since I have some 18 
> volts DC power supplies (wall warts) that I've used on some other 
> electronic music devices.
> My question is this - does an electronic music circuit that works fine 
> from a 9 volt DC supply work even better at 12 or 15 volts DC & why is 
> that so ?
> Logan
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