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Thanks Roman & Michael.</div>
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Logan</div>
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<div id="divRplyFwdMsg" dir="ltr"><font style="font-size:11pt" face="Calibri, sans-serif" color="#000000"><b>From:</b> Michael E Caloroso <mec.forumreader@gmail.com><br>
<b>Sent:</b> Monday, September 5, 2022 10:07<br>
<b>To:</b> Roman Sowa <modular@go2.pl><br>
<b>Cc:</b> prowlerraven32@hotmail.com <prowlerraven32@hotmail.com>; Synth-diy@synth-diy.org <synth-diy@synth-diy.org><br>
<b>Subject:</b> Re: [sdiy] Operating voltages questions about synthesizers</font>
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<div dir="ltr">Not all discrete transistors will work at higher voltage so you need the datasheet for those transistors for those OEMs. I found out the semi-hard way when using 2N2222 NPN in a circuit (there's a REASON why the 2N2222A was made available).
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<div>Same with any ICs.</div>
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<div>Electrolytics and tantalums do not like their maximum voltage rating exceeded.<br>
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<div>You really need to analyze the entire circuit AND the active devices used before changing the supply voltage. Not at all trivial.</div>
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<div>MC</div>
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<div dir="ltr" class="x_gmail_attr">On Mon, Sep 5, 2022 at 5:13 AM Roman Sowa <<a href="mailto:modular@go2.pl" data-auth="NotApplicable">modular@go2.pl</a>> wrote:<br>
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Depends what you call "sounds better".<br>
<br>
AFAIK input voltage, 9V in original, and 12V in your case is only used <br>
for speaker amplifier, comparator, and pullup resistors for OTA outputs <br>
in the filter.<br>
So the power amp may feel better, able to provide more power at lower <br>
distortion. For comparator it doesn't mean a thig. And for OTAs, well it <br>
changes the voltage of the output pullup resistor higher than OTA's <br>
power suply. That may affect how it works, introducing some nice <br>
distortion, increase levels, or whatever, but I'm only guessing here.<br>
<br>
The thing is, most of the circuit is powered from internal 6V regulator <br>
made with TO92 transistor, so if you change input from 9 to 12V, it has <br>
to dissipate twice more heat than before. Probably not much anyway, but <br>
it's easy to check with your finger.<br>
<br>
First thing I woudl do is to check current draw, how it changes when <br>
supply rises from 9 to 12. Next is to check how signal changes at OTA <br>
outputs.<br>
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Roman<br>
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W dniu 2022-09-05 o 09:33, Logan Mitchell Sr via Synth-diy pisze:<br>
> I am finally working on completing modifying my Electro-Harmonix EH 0400 <br>
> mini synthesizer that I purchased brand new around 1979/1980.<br>
> <br>
> Its original factory power supply was two 9-volt batteries connected in <br>
> parallel with no external power supply adapter jack installed so I <br>
> installed one some years ago to use a 9 volt DC power supply.<br>
> <br>
> Last night I connected a 12 volt DC power supply & noticed that the <br>
> synthesizer sounded a little better than when operating from the 9 volt <br>
> battery or from the 9 volt DC power supply.<br>
> <br>
> I'm thinking about adding a 7812 or 7815 voltage regulator circuit to <br>
> connect to the power connection of this synthesizer since I have some 18 <br>
> volts DC power supplies (wall warts) that I've used on some other <br>
> electronic music devices.<br>
> <br>
> My question is this - does an electronic music circuit that works fine <br>
> from a 9 volt DC supply work even better at 12 or 15 volts DC & why is <br>
> that so ?<br>
> <br>
> Logan<br>
> <br>
> <br>
> <br>
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