Powering an amp from just + and -?

19th November 2002, 09:20 PM

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 · 19th November 2002, 09:27 PM

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

19th November 2002, 09:30 PM

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 · 19th November 2002, 09:55 PM

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 · 19th November 2002, 09:58 PM

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

Nelson Pass · 19th November 2002, 10:24 PM

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

20th November 2002, 01:19 AM

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

22nd November 2002, 06:37 AM

So theres no way?

paulb · 22nd November 2002, 11:17 AM

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 · 22nd November 2002, 11:22 AM

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.

19th November 2002, 09:20 PM	#1
CryingDragon Guest	Powering an amp from just + and -? Is there any way to power an amp that would othewise use a dual - 30 0 + 30 supply off just a single + and - supply?

19th November 2002, 09:58 PM	#5
Equilibrium diyAudio Member Join Date: Oct 2002 Location: Mad Dog, Texas	Zen is single ended In order to employ a 0 and + power supply wouldn’t your amp have to be single ended?

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19th November 2002, 09:27 PM	#2
Nelson Pass The one and only Join Date: Mar 2001	By that if you mean 0 and +, then the answer is yes. A Zen is a good example.

19th November 2002, 09:30 PM	#3
CryingDragon Guest	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....

19th November 2002, 09:55 PM	#4
traderbam diyAudio Member Join Date: Jan 2002 Location: Earth	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

19th November 2002, 10:24 PM	#6
Nelson Pass The one and only Join Date: Mar 2001	No. You can build a fine push-pull amp with just a single supply.

20th November 2002, 01:19 AM	#7
CryingDragon Guest	Ackie! this amp is an STK hybrid with +VCC and -VEE and ground connections on the schematic,perhaps i should have mentioned that before....

22nd November 2002, 06:37 AM	#8
CryingDragon Guest	So theres no way?

22nd November 2002, 11:17 AM	#9
paulb diyAudio Member Join Date: Jun 2001 Location: Calgary	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.

22nd November 2002, 11:22 AM	#10
Christer diyAudio Member Join Date: Sep 2002 Location: Sweden	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.

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