How to run amp32 ans pre-amp from same power supply?

[Scratchy]

Alway isolate the audio input ground from the power ground, or you will have issues like this.

[legend95]

Hi, I know this thread is a bit old but I still haven't found a solution to this problem.

The situation is I am trying to run an Amp32 along with a pre-amp/mixer. The setup works perfectly when both are powered from separate supply's, however when they are both connected to the same battery (11.1v lipo) whenever there is a bass note it causes big pops on the speakers.

I have corrected my original setup so that PGND and AGND are isolated from the amp32 casing.

In another thread it was mentioned that you should never operate a power amp and pre-amp/mixer from the same power supply or you will get ground loops and other problems. Is there any way around this because for my application it would be impractical to add another battery.

Here is the pre-amp I am using: http://www.quasarelectronics.com/310...e-controls.htm

[V-bro]

Yep, as said the magic word is isolated regulator (or often called DC-DC converter) But the most magic is in the word ISOLATED!!

The preamp you use only uses an asymmetric PS voltage, so a Cincon CHB50 12-12 would do excellent, but probably overkill in terms of power. Traco power also have nice ones.... Do be prepared to the seemingly high prices these units have, once you've figured out there is state of the art switchmode tech in there and they have superb efficiency and use an actual transformer (hence being isolated) it is not surprising these units cost a little....

If you want it the cheap way then get a car audio ground loop isolator, but this will be in the signal path and will massively deteriorate the audio quality...

[V-bro]

It's actually a Cincon CHB50 12S12....

http://www.cincon.com/data/products/dcdc3_2/CHB50.pdf

Mouser have these for instance, but they are 50 watts, so a bit overkill...

[legend95]

Hi, thanks for the solution, this has been bugging me for some time now.

I was just wondering as a way to save money - would I be able to use a lower power isolated dc-dc converter to power the pre-amplifier (pre-amp only needs 40mA) and then connect the amp32 directly to the battery?

[V-bro]

Hi, thanks for the solution, this has been bugging me for some time now.

I was just wondering as a way to save money - would I be able to use a lower power isolated dc-dc converter to power the pre-amplifier (pre-amp only needs 40mA) and then connect the amp32 directly to the battery?

Yes that would work, go find one! You know what to look for now right...?

[V-bro]

http://nl.rs-online.com/web/p/isolat...633D4E4F4E4526

[V-bro]

http://www.tracopower.com/datasheet_g/tra1-d.pdf

http://www.tracopower.com/datasheet_g/ten6n-d.pdf

The upper link are 1 watt converters, though I recommend to use a little more power, and they do seem to allow only little input voltage variations...

Also when doing this do place two 10R 1/4 watt resistors in series with the outputs towards the preamp, if it ever fails these will act as fuses. They will also soften any current peaks at start up etc...

[legend95]

Thanks again V-bro. Those Traco 1watt converters seem ideal. I would go for the higher power model except it wont fit inside the tiny case I'm hoping to pack this all into.

Unfortunately I can't seem to find the 1 watt Traco anywhere. I might just settle for this one then, seems to have a pretty similar spec: http://uk.farnell.com/murata-power-s...12v/dp/1818364

Also would having the converter mounted inside the casing close to the amplifiers interfere with the audio signal at all?

[MickB]

Farnell UK have Traco 2 watt converters with a wide input range which will accommodate variations in battery output. I'm using an 18V-36V input/dual output version to power a combined preamp and bass boost/cut circuit in a 24V battery powered system.