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Audio Research 70's Gear

K

KeithL

Active Member
I need some opinions fast as these are available and probably won't last.

Preamp audio research sp-4 good condition
Amp audio research D-100a good condition

I can pick these up with a tuner for $500

I have not seen them or heard them yet, but if they play, is that a good deal?

What are the chances these would need some work?

Thanks
Keith
 
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Always nice stuff. Factor in $$ for restoration at AR, however, as this stuff is the better part of 40 years old now. Few schematics float around and they made production changes on the fly. Good news is they will support the gear for the most part.

No comments on pricing as the thread will get moved.

Cheers,

David
 
KeithL said:
I need some opinions fast as these are available and probably won't last.

Preamp audio research sp-4 good condition
Amp audio research D-100a good condition

I can pick these up with a tuner for $500

I have not seen them or heard them yet, but if they play, is that a good deal?

What are the chances these would need some work?

Thanks
Keith
Click to expand...

I'd be carefil of the D-100A. There are two line driver modules that Audio Research doesn't sell anymore. The "AM-1" and the AM-2" modules.
 
Jon_Logan said:
I'd be carefil of the D-100A. There are two line driver modules that Audio Research doesn't sell anymore. The "AM-1" and the AM-2" modules.
Click to expand...

So are these components guaranteed to fail at some point and time and I would have an expensive paper weight?

Have you heard this amplifier? How would you rate it?
 
ConradH rebuilt an SP-4 and wrote about it.

The SP-4 was a first effort in the transistor era for ARC and it caused the company some difficulties as it was not up to the performance levels of their tube gear. That and the AM modules would make me wary but if they work, it is probably a fair deal. The SP-4 is a full featured slim preamp and looks good.

I recommend more research...audio asylum might have more comments on these units.
 
I'd go for the deal. The SP-4 still commands good money on eBay. My write-up is here. IMO, it's a wonder that ARC can sell anything at all that uses potted modules, but they do seem to have good reliability. From what I can tell, any of them in the SP-4 could be replaced with a nice LME op-amp without a lot of trouble. It would require fabricating a small PCB, either etched or just perfboard, connecting the necessary pins and ignoring the ones with the big caps hanging off. Not beginner stuff, but not rocket surgery either.
 
So I am not getting a warm fuzzy feeling about these components, not very many good reviews out there. It sounds like these were not very good components to start with and would most likely need to be rebuilt at their satge in life.

I currently have an Aragon 18k mkii and a 4004 mkii. Would these AR pieces be an improvement?
 
KeithL said:
So are these components guaranteed to fail at some point and time and I would have an expensive paper weight?

Have you heard this amplifier? How would you rate it?
Click to expand...

Failures are not guaranteed, No.

But ..... should one occur on the amp, it does require extra innings to get it fixed.

I used to work for a servicing ARC dealer and we did buy a fair amount of the AM-1 and AM-2 modules. The last time I worked on one that required a module, ARC sent me a module un-potted. I should have took the time to reverse engineer it, but I didn't. I hindsight, that was probably just about the time that ARC stopped supporting that part.
 
If they haven't had a rebuild by now, it's time! The stuff is built like a tank and looks great, so it's worth the time and expense. IMO, in rebuilt condition they won't lose value. OTOH don't lose a minutes sleep if you decide they aren't for you- there's lots of other newer good stuff out there.
 
ConradH said:
If they haven't had a rebuild by now, it's time! The stuff is built like a tank and looks great, so it's worth the time and expense. IMO, in rebuilt condition they won't lose value. OTOH don't lose a minutes sleep if you decide they aren't for you- there's lots of other newer good stuff out there.
Click to expand...

OK, so my question would be what is the expense?
 
Well, the SP-4 isn't difficult. Figure a couple hours labor at whatever labor rate your shop uses. I don't know how much the main filter caps would cost, but the rest of the caps are probably under $20. I think a bad module could be dealt with because the supply rails are +/- 20 VDC, which is opamp territory. The D100 is another matter. The caps would be more expensive and the modules run at the full +/- 50 VDC. It probably wouldn't be worth it to engineer a drop in module if one were bad. You'd want a parts doner, or use the chassis for a whole new amp design. I would not buy a bad D100 except as a chassis for cheap.

edit- Have done a bit more research on the D100 and the comments aren't very positive. I'd want to be darn sure it's working perfectly and that the tuner referred to is worth at least 1/3 of the purchase price. The D100 seems to be a good project for a DIY person, not so much if you have to pay to have it worked on. Apparently the A and B versions are quite different, though both are service problems. Understand that I've never actually worked on one, though after staring at the schematics for a while I do think I have a way to deal with defective modules.
 
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OK, so I went to play the D-100a last night and it has developed a hum in the right channel and the music comes in and out sporadically. Any ideas?
 
I can tell you that my recapped and restored SP-4 really sounds lovely. Before service it had a flattened soundstage, some audible hiss, and maybe a bit of shrillness. When it came back it sounded open, effortless, quiet, with an excellent phono stage. I really like it.

Also, ConradH knows what he's talking about!

I have no experience with the D100 amp.
 
KeithL said:
OK, so I went to play the D-100a last night and it has developed a hum in the right channel and the music comes in and out sporadically. Any ideas?
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Did you do anything to it after getting it other than play it? Might be time for that 100K service that changes the caps and such. If you don't know how, find someone who does and get the unit back right.

Take it to Knoxville and let Terry DeWick have a go at it. His banner ad is below. Great work, very reasonable, knows tube gear and McIntosh approved. Gotta be good enough for a D-100 from ARC.
 
Blue Shadow said:
Did you do anything to it after getting it other than play it? Might be time for that 100K service that changes the caps and such. If you don't know how, find someone who does and get the unit back right.

Take it to Knoxville and let Terry DeWick have a go at it. His banner ad is below. Great work, very reasonable, knows tube gear and McIntosh approved. Gotta be good enough for a D-100 from ARC.
Click to expand...

I spoke with Tom Manley a few months ago and he said they arent working on Audio Research anymore because the replacement parts are to expensive from AR parts department now I don't know if that includes Terry working on it.
 
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