Electrocompaniet AW 60

D

depaj

Active Member
Hello,

A friend left me his 2 Electrocompaniet AW60FTT amps with the request to bridge them to be used as two mono blocks and that in itself is pretty straightforward but the thing is they don't seem to be all that healthy.
After doing some tests I noticed they start cutting of at high frequency : above 6khz on one it goes down very fast and at 12khz I have no output at all, on the other one its a little higher, I start losing amplitude at 10khz and above 18khz there is no output. a square wave comes out as something looking like a sawtooth with rounded angles. There don't seem to be any schematics out there so it's hard to start diagnosing. If anyone here can provide the schematics that would be great, otherwise if anyone is familiar with these amps and this particular problem that would also be very welcome.

Thanks
 
Curious about the method used to bridge them.

Is the response anomaly present during normal/2-ch use or only when bridged?
 
Yes indeed norwegian and they very carefully keep their schematics. I read that is was impossible to get them but I did try to email them, they told me they only provide them for their authorized service points.

I haven't bridged them yet so it's present in the standard configuration.
It's pretty easy, just connect pin 3 of one xlr to pin 2 of the other and vice versa.
 
It seems the aw60 is very close to the aw120 of which I got a schematic. the problem is occurring in the first differential stage the negative feedback loop is only returning the very high frequencies that in return cut those from the input signal fed through the rest of the amp.
 
The AW60 is a wery tiny amp, and it will stay tiny even bridged. Notice the lamp-cord that runs from the power-inlet in the rear to the powerswitch in the front.
Replacing the lampcord with a 12-14awg solid core will give the little tiny amp quite a bit moore authority.This lampcord is used even in the bigger EC-amps

I`m running a totally rebuilt AW-250DMB btw, kind of know my EC`s. Mr.Abrahamsen told me that he included my main upgrade in his anniversary-amp; heavy solid-core copper-rails from the rectifiers caps and out

http://www.hifishock.org/gallery/el...t/power-amplifier/aw60ftt-electrocompaniet-1/

http://www.hifishock.org/gallery/electronics/electrocompaniet/power-amplifier/
 
Tiny or not tiny isn't really the issue here :). Before considering modifying anything I would love to get them working correctly first. In bridged mode they will give plenty power for what he needs.
If you have a schematic or service manual or even an idea on what might be wrong here that would be very welcome.
 
Found the problem causing the strange frequency response, the two shorting plugs inserted between negative and ground on the xlr inputs were not making contact. That being solved, the two models are different versions which means that they don't have the same gain (that is putting it lightly, they aren't even in the same ballpark). The only difference I see in the actual amplifier stage (the power supply rails being the same) is a difference in transistor references (2sa970/2sc2240 on one, 2sa1038/2sc2389 on the other) but these are equivalents and a second differential input in parallel with the fets that isn't there in the later model (accompanied by two extra 750ohm resistors). Would it be ok to just add the components on one or remove on the other to match gain ?
 
Does anyone know the procedure for adjusting the different pots on these ? Does a load have to be connected for the dc offset, do I connect do the speaker terminals or to the DC and DC1 test points ? Same question concerning the bias adjustment (just 1 test point per channel, is the measurement taken according to ground ? What value am I looking for ?). I sent a mail to EC but they said I should check with one of their distributors.
 
Yes it is but it doesn't show anything about the adjustments, I sent a message to the person that uploaded the schematics and will see. I think the nemo 600 are playing on different level but still, they should be pretty good.
 
Last edited:
clinic-audio said:
Does a load have to be connected for the dc offset,

no , of course
Click to expand...

I've seen some service manuals that asked to connect a load and a source before adjusting so I wouldn't say "of course". I noticed that the reading at the speaker terminals are quite different with/without load and even more so with/without a source connected.
 
OK , but usually an offset control is made :
- without load
- without signal
If you connect a load this will affect the DC value
 
That's how I usually do it yes, just wasn't sure here as the adjustment seems to be really sensitive to those two things.
Apparently shorting the inputs to ground is the way to go here.
 
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