Acoustic Research Amplifier (solid state) help needed

RobertSt · 15th January 2005, 04:54 PM

OK, I searched the forum on this one, but didn't found anything, so here goes...

Someone threw an AR amplifier in my lap as part of a deal with a pair of AR-speakers I bought.

The amp has a problem in the R channel when output goes over 20%, esp. at lower frequencies and low impedances (4 ohms).

Input is sine on top, output from speker terminal.

Questions:
A: Where can I find a service manual / schematics?
B: Anyone seen this before, clues?
C: Is this amp even worth salvaging?

I have some experience in tube-amps, but less in solid state. Ironically It's rather simple to find documentation on old tube-amps and new solid-states. But in between those...

Damon Hill · 15th January 2005, 05:16 PM

I think this was a good quality amplifier for the time; possibly
a quasi-complementary output stage, may have been
direct-coupled.

The Classic Speakers Page (http://www.****nal.net/speakers/)
had schematics, but appears to be completely offline at the
moment.

I'd check power supply first, especially low-voltage supplies
and any regulated supplies. It's been my experience that
electrolytic caps in those supplies are unreliable, going open-
circuit or high impedance.

If the output stage is capacitor-coupled, check those capacitors
as well.

After that, check the driver and output transistors.

Damon Hill · 15th January 2005, 05:18 PM

Apparently the character string '****' in ****nal is verboten.
Thats a r s e n a l.net

Bill Fitzpatrick · 15th January 2005, 06:22 PM

Quote:

Originally posted by Damon Hill
Apparently the character string '****' in ****nal is verboten.

That shows you how pervasive silliness is.

tschrama · 15th January 2005, 06:34 PM

sometimes this helps:

http://web.archive.org

more precisely:

http://web.archive.org/web/*/http://....net/speakers/

jaycee · 15th January 2005, 07:43 PM

a r s e n a l over here is a football team. So that makes the censor look a bit silly.

Bill Fitzpatrick · 15th January 2005, 07:44 PM

Not to mention what happens to: ****nococcus frondosus.

Beam me up.

RobertSt · 15th January 2005, 08:13 PM

ROTFL!... Seriously: I have already 'scanned' that site. The AR amps there are too modern. I have found one copy of a manual at:

W7FG

It was in poor condition and no schematics. I have not yet received it so I can't tell.

Yes, there is a large multicap. Same thing as the old Dynacos; may have to be replaced.

Since it seems to be so har finding data on this one, maybe that is telling the tale? It is rare and should be salvaged?

RobertSt · 29th January 2005, 02:45 PM

UPDATE: I have received the manual. It had, as I was told, no scematics. Unfortunately. But it makes a reference to it: Dwg. #2935-10.
With that, all measurements, and procedures are described.

This means I am really interested in this drawing right now. Anyone?

djk · 29th January 2005, 06:11 PM

If I remeber correctly the old AR amp is kind of a POS with an interstage coupling transformer to drive all NPN outputs.

I would gut it and use the chassis for a new project.

15th January 2005, 04:54 PM	#1
RobertSt diyAudio Member Join Date: Jan 2005 Location: VASTERAAS	Acoustic Research Amplifier (solid state) help needed OK, I searched the forum on this one, but didn't found anything, so here goes... Someone threw an AR amplifier in my lap as part of a deal with a pair of AR-speakers I bought. The amp has a problem in the R channel when output goes over 20%, esp. at lower frequencies and low impedances (4 ohms). Input is sine on top, output from speker terminal. Questions: A: Where can I find a service manual / schematics? B: Anyone seen this before, clues? C: Is this amp even worth salvaging? I have some experience in tube-amps, but less in solid state. Ironically It's rather simple to find documentation on old tube-amps and new solid-states. But in between those...

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Solid state guitar amp. help needed!	pilt	Solid State	8	17th April 2011 06:25 AM
The Solid State Wiki - Your solid state reference guide	Jason	Solid State	0	25th June 2002 05:26 PM

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read


	Please consider donating to help us continue to serve you. Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving

15th January 2005, 05:16 PM	#2
Damon Hill diyAudio Member Join Date: Mar 2001 Location: Auburn, WA (somewhere between Seattle and Tacoma) Blog Entries: 1	I think this was a good quality amplifier for the time; possibly a quasi-complementary output stage, may have been direct-coupled. The Classic Speakers Page (http://www.****nal.net/speakers/) had schematics, but appears to be completely offline at the moment. I'd check power supply first, especially low-voltage supplies and any regulated supplies. It's been my experience that electrolytic caps in those supplies are unreliable, going open- circuit or high impedance. If the output stage is capacitor-coupled, check those capacitors as well. After that, check the driver and output transistors.

15th January 2005, 05:18 PM	#3
Damon Hill diyAudio Member Join Date: Mar 2001 Location: Auburn, WA (somewhere between Seattle and Tacoma) Blog Entries: 1	Apparently the character string '**' in **nal is verboten. Thats a r s e n a l.net

15th January 2005, 06:34 PM	#5
tschrama diyAudio Member Join Date: Jul 2001 Location: The Netherlands	sometimes this helps: http://web.archive.org more precisely: http://web.archive.org/web/*/http://....net/speakers/

15th January 2005, 07:43 PM	#6
jaycee diyAudio Member Join Date: Apr 2004 Location: Norwich, UK	a r s e n a l over here is a football team. So that makes the censor look a bit silly.

15th January 2005, 07:44 PM	#7
Bill Fitzpatrick diyAudio Member Join Date: Jun 2001 Location: Eugene, OR	Not to mention what happens to: ****nococcus frondosus. Beam me up.

15th January 2005, 08:13 PM	#8
RobertSt diyAudio Member Join Date: Jan 2005 Location: VASTERAAS	ROTFL!... Seriously: I have already 'scanned' that site. The AR amps there are too modern. I have found one copy of a manual at: W7FG It was in poor condition and no schematics. I have not yet received it so I can't tell. Yes, there is a large multicap. Same thing as the old Dynacos; may have to be replaced. Since it seems to be so har finding data on this one, maybe that is telling the tale? It is rare and should be salvaged?

29th January 2005, 02:45 PM	#9
RobertSt diyAudio Member Join Date: Jan 2005 Location: VASTERAAS	UPDATE: I have received the manual. It had, as I was told, no scematics. Unfortunately. But it makes a reference to it: Dwg. #2935-10. With that, all measurements, and procedures are described. This means I am really interested in this drawing right now. Anyone?

29th January 2005, 06:11 PM	#10
djk diyAudio Member Join Date: Feb 2001 Location: USA	If I remeber correctly the old AR amp is kind of a POS with an interstage coupling transformer to drive all NPN outputs. I would gut it and use the chassis for a new project.

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)