Behringer A500 as a DIY project

[derouineau]

I am in the middle of building the quasi FET design and was starting to wonder how to package it nicely in a box with heatsinks , power supply, etc...
I bumped into the A500 pictures and thought that for $180, it might provide a lot of hardware to get there.
(a box, heatsinks, transformer, connectors, knobs, potentiometers, etc... might cost as much).

Does anybody have the schematics of the A500?

Has anybody tried to mod this guy before?

Thanks,

JLD

[beppe61]

Originally posted by derouineau
I am in the middle of building the quasi FET design and was starting to wonder how to package it nicely in a box with heatsinks , power supply, etc...
I bumped into the A500 pictures and thought that for $180, it might provide a lot of hardware to get there.
(a box, heatsinks, transformer, connectors, knobs, potentiometers, etc... might cost as much).
Does anybody have the schematics of the A500?
Has anybody tried to mod this guy before?
Thanks,
JLD

Dear Sir,

I am very interested in this amp.
Thank you for the pictures. The toroid in particular is very impressive for the price.
I would like to ask you:
1) did you listen to it?
2) what do you think is the VA rating of the transformer?
3) do you think it would be able to drive also demanding loads?
4) any links to reviews or similar?

Thank you very much indeed.
Kind regards,

beppe

[derouineau]

Well unfortunately I am in the same situtation as you are.
I don't own it...
I got these pictures from a guy, I think on AVS, but I could not get in touch with him for more info.
I will try get back to the links I found before but here are a few to start with:
http://forums.audioholics.com/forums...ad.php?t=17004
http://mysite.verizon.net/vze4c5pt/id11.html

I am surprised that nobody on diyAudio has been involved with this amplifier.

JLD

[beppe61]

Originally posted by derouineau
Well unfortunately I am in the same situtation as you are.
I don't own it...
I got these pictures from a guy, I think on AVS, but I could not get in touch with him for more info.
I will try get back to the links I found before but here are a few to start with:
http://forums.audioholics.com/forums...ad.php?t=17004
http://mysite.verizon.net/vze4c5pt/id11.html
I am surprised that nobody on diyAudio has been involved with this amplifier.
JLD

Dear Sir,
thank you so much for your very kind and valuable reply.
I have already a nice pro amp, a Samson Servo 260 (130W/4ohm).
I like the sound on the mid and high but the bass response is weak.
After some analysis I think that the reason is an undersized transformer.
I am surprised by the dimension of the toroid inside the A500, very fundamental condition for a amp with good current delivery.
Thank you for the most interesting links.
I am also interested about another Behirnger amp, the EP1500 even more after reading this opinion on the link you have provided:
" I haven't auditioned the A500, but based on my experience with the pro line EP1500, I'd have high expectations. I'm using an Anthem AVM20 digital preamp with B&W 801s with a Behringer EP1500 amp, and the sound is incredible.
The EP1500 has really restored my feelings about how much I love music and good sound reproduction. I just replaced a $2000 hi-end audiophile amp with this ridiculously cheap amp, and it sounds better in every respect: ... -John "

Well I would call this amazing, wouldn't you ?
One thing is sure, high end amps are quite overprized.
Please excuse me if I will take the liberty of disturbing you after reading carefully the links.
As you can understand I am undecided amon the two.
The bigger has an annoying fan but more power.
The smaller is very nice indeed and I like very much indeed its internal layout and its nicely big toroid.

Thank you very much again.
Kind regards,

beppe

[derouineau]

I have been looking at EP1500 as well as it gets good reviews.
It is considered as a clone of the QSC RMX 1450 for which you can find the schematics here : http://www.qscaudio.com/support/libr...ms/rmx1450.zip

The only issue for me would be the fan but if you don't need a lot of power on average, it might be possible to use a slower and less noisy fan.

I was also looking at the A500 as a potential for DIY project.
Upgrading the capacitors, changing some electrolitycs and eventually replacing the power pcb. But I would like to konw a little bit more beforeI jump on it.

To try answer your question on transformer rating, just based on the diameter (around 6 inches), I would expect this transformer to be in the 500 VA range.

JLD

[Nigel Goodwin]

Originally posted by derouineau
I have been looking at EP1500 as well as it gets good reviews.
It is considered as a clone of the QSC RMX 1450 for which you can find the schematics here : http://www.qscaudio.com/support/libr...ms/rmx1450.zip

From previous posts here it's not just a clone, but EXACTLY the same amplifier (even same numbers on the PCB's) - presumably both QSC and Behringer buy them from the same original Chinese manufacturer?.

A quick google finds the QSC for sale at $429 and the Behringer at $279 (on the same site) - I know which I'd buy!

[beppe61]

Originally posted by derouineau

1) I have been looking at EP1500 as well as it gets good reviews.
It is considered as a clone of the QSC RMX 1450 for which you can find the schematics here : http://www.qscaudio.com/support/libr...ms/rmx1450.zip
2) The only issue for me would be the fan but if you don't need a lot of power on average, it might be possible to use a slower and less noisy fan.
3) I was also looking at the A500 as a potential for DIY project.
Upgrading the capacitors, changing some electrolitycs and eventually replacing the power pcb.
But I would like to konw a little bit more beforeI jump on it.
4) To try answer your question on transformer rating, just based on the diameter (around 6 inches), I would expect this transformer to be in the 500 VA range.
JLD

Dear Sir,
thank you vey much again.
1) Actually your words confirm my info about the EP1500.
I read in a "Magneplanarists" forum that this amp has remarkable "driving abilities" and good overall sound.
2) The fan noise is indeed an issue. It has a 24Vdc power supply, unfortunately different from 12 Vdc standard for PC.
Anyway I think it is possible to slow it down with a suitable resistor or replace it with a less noisy unit.
The transformer should be at least 800 VA, a nice one.
As I said a high VA transformer is a must for me.
3) I hear that Behringer does not provide service manuals of its products (unforunately).
It should be very difficult to find the schematics.
4) Thank you for the info.
I hoped more. I am a little worried about a only 500 VA rating.
Actually my first mod would be, if it were possible, the replacement of the transfomer with another one more powerful of at least 800 VA (better two 500VA/each space allowing), hoping that in the circuit there are no current limiting devices/circuits of course.

I will come back to this 3D quite often because I am very interested in this unit if the transformer is replaceable.

Thnak you very much indeed.
Kind regards,

beppe

[beppe61]

Originally posted by Nigel Goodwin

1) From previous posts here it's not just a clone, but EXACTLY the same amplifier (even same numbers on the PCB's) - presumably both QSC and Behringer buy them from the same original Chinese manufacturer?.
2) A quick google finds the QSC for sale at $429 and the Behringer at $279 (on the same site) -
I know which I'd buy!

Dear Mr. Goodwin,

thank you very much for your interesting infos.
1) This is a very fundamental point. If the two units are really identical one would pay a premium price for the brand mark on the case.
I seem to remember that the PCB colours were not the same.
It could be that the unit manufactured for QSC has a better quality control procedure ?
2) Yes. I understand. Nevertheless I am still not sure that the two units are 100% equal.

By the way the unit that interests me most is the A500.
But while I know that the EP1500 can drive quite well even demanding loads I am not so sure about the A500.

Thank you sincerely and kind regards,

beppe

[beppe61]

In the end I bought an A500.
Overall a very nice amp for the price (180 euro).
I have pushed it with my Dynaudio speakers and found that at mid to high level the amp strains and the sound become thin and compressed.
Sign of a limited current delivery at some point.
To be honest I have to say that my speakers are demanding in terms of needed current from the amp.
Looking inside and I see a quite big (about 600VA ?) mains transformer (regulation ?), 4 small filter caps (3300uF/100V) of unknown quality and discrete diodes bridge of 6A on each PCB (one per channel).
Do anyone own the schematic?
I strongly think that the first mod should adress the diodes bridge (with something like a 25A units) and the too small filter caps (4X10.000uF of good quality could help).
But I have to find the schematic first.


Kind regards,

beppe

[Patrik Floding]

Hi all!
I noticed that Hi-fi World had measured a lot of old-fasioned crossover distortion on this amp. Any idea if it is feasible to crank up quiscent current on this amp?
Rgds