Behringer A500 as a DIY project

[Nigel Goodwin]

Originally posted by beppe61

And of course QSC amps are better built with better components and of course placed at a higher cost.

You don't think then that the QSC amp is designed and built in exactly the same factory as the Behrigner one then? - I would strongly suspect it is!.

[beppe61]

Originally posted by Nigel Goodwin
You don't think then that the QSC amp is designed and built in exactly the same factory as the Behrigner one then? - I would strongly suspect it is!.

Yes Sir, I believe so as well.
Maybe two lines of the same design, aimed at different price targets.
Anyway the A500 looks quite well built, considering its very low price.
I can say nothing about its quality but the transformer in particular looks like a 600VA "onion" (!).
Kind regards,

beppe

[beppe61]

Originally posted by beppe61


I correct my words.

Anyway the A500 looks quite well built, considering its very low price.
The transformer in particular looks like a 600VA (!) thing.
By the way I can say nothing about its quality.
It could be a "fake" 600 Watter ....
I am sure that QSC toroids are very good and substantial instead.
And this is an important piece in an amp after all.

Kind regards,
beppe

[Pulse-R]

this guy has done quite a bit on the A500 from the looks.

http://db.audioasylum.com/scripts/t.pl?f=amp&m=81545

not sure about if he's talking about the supply caps, or 'output' caps that he is bypassing - guess I'll find out later this week, I am getting an A500 to poke around in.

[Cloth Ears]

This item from ebay was a modified A500. These mods were listed (no I didn't buy it):

1. Additional filter caps (original amp has only 6600uf per channel, I have added on 28,000uf each channel...that is like 4 times more) so that there is more raw power when it is playing in high levels.

2. There are 2 op-amps in each channel. They are for receiving balance signal, converting them into single path for volume control. Behringer uses JRC4558 with a slew rate of only 1V/us. I have changed all op-amp in both channel to Burr Brown OPA2134. OPA2134 has slew rate of 20V/us, wider bandwidth (8Mhz), and lower noise. The result is quieter, faster and clearer high ends.

3. Changed input electrolytic caps to audio grade caps. These caps are in sigal path, so they should be of high quality. I used Nichicon audio caps and Philips MKP.

[beppe61]

I feel some improvements should be gained by "cleaning" the single ended path (i.e. bypassing op-amps, volume controls and even -if possible- coupling caps) and using only this as input.
I would replace the main power supply caps with bigger and better quality ones as well.
As usual, the main problem is with the available space on the pcbs.
The original caps are small in diameter (26 mm) and there are components all around them limiting the space free on the pcb.
This I do not understand.
Much better would be main caps short and large with the possibility to put at least 20.000-30.000uF/channel, a reasonable amount in general.
I believe that a little more attention in the design could have brought a nice step-up in performance, with a small cost.

Regards,

bg

[Minion]

I have a schematic of the Behringer EP-2500 if someone needs it...?

[Cloth Ears]

Originally posted by Minion
I have a schematic of the Behringer EP-2500 if someone needs it...?

Champion!

[sympartysant]

Jipieh!

Being an owner, I'd like to have the schematic of that EP2500 too.
please :-) (Can't email you yet because I just registered...)

Greetz

[AudioFi]

I would love the Schematic also, I blew my ep2500 a week ago.
Thanks