Powering an amp from just + and -?

[CryingDragon]

Is there any way to power an amp that would othewise use a dual - 30 0 + 30 supply off just a single + and - supply?

 

[Nelson Pass]

By that if you mean 0 and +, then the answer is yes.
A Zen is a good example.

 

[CryingDragon]

Yeah because my amp is goin in a very small case and the transformer is going in a diff case for emi and such shielding so instead of trying to use a xr5 or whatever it's called 3 wire mic cable for my power i could just use a cord from my old playstation (now deceased) with the quick connecter in the amp and use only 2 conductors.

EDIT: i've been to your site and looked around and can't find any info on the ZEN....

 

[traderbam]

It is possible to build two amps and bridge them to achieve what you want. Some modifications will be needed to bias the input ground between the supply rails. You'd need to watch out for things like psu decoupling capacitors that originally connect to the 0V gnd and make sure their currents don't modulate the input ground.

I'm not sure what Nelson is talking about. I can't think of many ways to use a single split-rail amp without doing something nasty like a series cap to the speaker with the other end of the speaker tied to one of the supply rails.

BAM

 

[Equilibrium]

Zen is single ended

In order to employ a 0 and + power supply wouldn’t your amp have to be single ended?

 

[Nelson Pass]

No. You can build a fine push-pull amp with just a
single supply.

 

[CryingDragon]

Ackie! this amp is an STK hybrid with +VCC and -VEE and ground connections on the schematic,perhaps i should have mentioned that before....

 

[CryingDragon]

So theres no way?

 

[paulb]

Your question should be: can I modify this amplifier to run from a single supply voltage?
Short answer: No.
Long answer: You could add a circuit to derive the midpoint of the supply voltage, and use that as ground. It's not worth it just to save a connector.

 

[Christer]

The simplest way would be to use two electrolytics in series and
use the midpoint as ground. This works if regulated power
is not required, but just as paulb said, it is hardly worth the
cost if the only purpose was reuse an old connector and cable.

 

[mhennessy]

Quad did this quite successfully in their 306 and 520 amplifiers - using 2 electrolytics and 2 transistors to steer the midpoint to Vcc/2

The rest of the amplifier was 'conventional' in that it required a split supply. Advantages: automatic protection from output DC faults and negative feedback reduces any ill-effects of the capacitor-split. Drawbacks: both capacitors should be rated at the total supply voltage, else a DC fault (eg shorted output transistor) will ensure that the full supply voltage is placed across one of the capacitors.

Check out this thread for a schematic...

 

[CryingDragon]

ok thanks,i have a very small case so it looks like i'll have to use my 3 way connector. (only ABSOLOUTELY nessasairy parts go in)