Behringer A500 as a DIY project

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#63
Behringer A500 and EP1500

Great info! I own a Behringer A500 and an EP1500. Every thing was great until a few days ago when I started getting distortion on the A500. I would appreciate it if one of you could please send the schematic and/or service info on these amplifiers.

I would email you directly but the board will not let me send emails yet! My email is dkmahan@yahoo.com.

Thanks!
 
#64
Hello, I saw this thread and subsequently joined the forum!

I too have an A500 amplifier, which I inherited from a previous tech. Channel 2 died: the upper (presumably op amp power supply) 5W power resistor between R35 and D29 blew up. (The board is burned too badly right there to be able to read the part number!) Has anyone else experienced this?

It would be great if I could also get the schematic for this amp. Thanks!

BTW, I have noticed that when running a sub the remaining channel of this amp has a strange way of choking when it gets close to or beyond clipping. Sometimes it seems to produce almost a weird whistling sound! And yes, the filter caps do seem a tad small... 🙁
 
#65
hi all - I came across this forum when searching for info on the behringer a500 amp. after reading up on it, I decided to buy - but then found the front to be quite ugly 😉

I fixed that. or, the fix is in progress but its a lot better now than it was before (imho).

here's a link to my flickr set of shots:

http://www.flickr.com/search/?s=int&ss=2&ct=6&w=all&q=a500+diy&m=text

some highlights:

opening up the front to see what we need to do to get that UGLY bezel removed:

http://www.flickr.com/photos/linux-works/2629400844/
An externally hosted image should be here but it was not working when we last tested it.


http://www.flickr.com/photos/linux-works/2628582415/in/photostream/
2628582415_60f6424ce2.jpg


the display board:

http://www.flickr.com/photos/linux-works/2629401984/in/photostream/
2629401984_6930eaa7d6.jpg


http://www.flickr.com/photos/linux-works/2628583605/in/photostream/
2628583605_91bc8c04ac.jpg


an end amp section:

http://www.flickr.com/photos/linux-works/2641214616/in/photostream/
2641214616_bbffd3e879.jpg


http://www.flickr.com/photos/linux-works/2641215096/in/photostream/
2641215096_29f607637d.jpg


the front and top, disassembled:

http://www.flickr.com/photos/linux-works/2640387307/in/photostream/
2640387307_9dc99af000.jpg



first attempt at using plexiglass for new bezel:

http://www.flickr.com/photos/linux-works/2640647759/in/photostream/
An externally hosted image should be here but it was not working when we last tested it.


my DIY mod to remove the pot from the audio path:

2650432864_9244fd9472_o.jpg

2650515068_0cfd384710.jpg

2650637614_f8ede8fd84.jpg


http://www.flickr.com/photos/linux-works/2649807447/in/photostream/
2649807447_ba45d72c58.jpg

2650636808_ec578ce81b.jpg



and finally, putting a proper power switch up front (sort of) in a quick manner:

http://www.flickr.com/photos/linux-works/2651565968/
2651565968_09fa5ec7fc.jpg


http://www.flickr.com/photos/linux-works/2651566738/in/photostream/
2651566738_7419b373d5_o.jpg



hope that's not too many photos 😉 that's also one of my hobbies along with audio.


so far, I'm really enjoying this amp. it replaced a hafler dh220 that had some transformer hum. this amp sounds as good (or better) in every way I can personally tell. $199 well spent!

/bryan
 
#67
Excellent Bryan. I'm planning on getting 3 or 4 of these in the next few months to run the active side speakers and the passive rears in my new music/HT system. It's not worth building amps for the price I can get these and they look better with your mods.
 
#69
Hi,

Your thread interests me here as I can't make my mind up which amp to buy.

I'm looking at the Behringer A500, EP1500 and phonics MAX250.

I have a pair of Klipsch F-1, 93db, 2 -way. (100W cont, 400W max).

It's either:

bi-amp with 2 x phonic MAX250 (60w per channel at 8 ohms, total 120 w per channel if I bi-amp)
or
1 x A500 amp
or
bi-amp with 2 x A500 (going over my budget here and not sure if the expense would outweigh the sonic advantages of bi-amping without an electronic crossover)
or
1 x EP1500.


The speakers are very sensitive as you see and the amps will be in the living, so something quiet and inconspicuous would be better. EP1500 has the loud fan.


Any advice would be appreciated.
 
#70
Brit,

- there is no advantage to biamping without an electronic xover, so dotch this idea.
- the EP series can have the fans quietened
- in tests I have read, the A500 does 120/8R and 180/4R so it doesn't meet it's published spec
 
#71
linuxworks said:
hi all - I came across this forum when searching for info on the behringer a500 amp. after reading up on it, I decided to buy - but then found the front to be quite ugly 😉

I fixed that. or, the fix is in progress but its a lot better now than it was before (imho).
Click to expand...


So why not just mount it where you couldn't see the front?, or I am I just too cheap? 😀

Love the pictures by the way!.
 
#72
I came across this forum when searching for info on the behringer a500 amp. after reading up on it, I decided to buy - but then found the front to be quite ugly
Click to expand...


When you bypassed the volume pots what effect did this have on the gain level?

Did the bypass have the effect of setting the gain at max?
 
#74
Any idea if the Phonic MAX250 has the toroidal transformer?

Looks too slim to contain one of these.

Also I don't see any mention of Bridge ability in the manual. Just Parallel.

I'm thinking 60 Watts per channel will be plenty to drive the tweeters on my Klipsch of 93db.
 
#75
Help: Trying to fix A500 & mod EP2500

Hello all,
I have a loudly buzzing A500 and a working EP2500. My 500 has been sitting on a shelf in the back of my closet collecting dust, and I just ran across this site and figured that I would try to fix it. I would also like to try to modify/upgrade my EP2500. So far (fingers crossed) my 2500 is working fine, but I have heard of a lot of problems with Behri amps in general. I am looking for the repair manuals or schemos of any or all of these amps (A500, EP1500, and/or EP2500). Could anyone here please email me this info? My email is linguisticat(at)hotmail.com. Thank you very much in advance.
 
#76
John Audio said:
I also have copies of the EP1500 and EP2500 power amplifier schematics - and would like them to be widely available.
I wish that Bearstrangler didn't have the restictive policy of not making diagrams available - as equipment, especially that used professionally, must be promptly field serviceable.

They are too big to post directly - but please PM me, with a real e-mail address, if you would like either (or both) schematics.
Click to expand...


Hello there i also need the two schematics if it is easy for you. thanks
 
#78
A500 schematics

I got this one to repair. The guy who asked me said that shipping would be equal to the cost of new amp. (180 USD) And that defect was output stage transistor not tightened to the heat sink. That’s to the question why these are cheappo things. Not qualified workmanship and lack of quality control.


Please send me the schematics, and who knows why there are no insulation between output transistor’s collectors and heat sinks?

Jus started to explore this topic most of discussion is on the look and where it was made. Alas.

please sent the drawings to slmnv5 at icmail.net

thanks to all
 
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