Audio Research SP3A-1

[jackinnj]

The OP isn't trying to "gild the lily", he's just trying to get it to work. Without avid DIY experience, without benefit of a signal tracer, or scope just get one new 12ax7 and put it into the various locations until you find the bum tube.

Not a bum tube? look for dirty switches. easy to clean with isopropyl alcohol and it dries quickly.

 

[Duke58]

To compare a Marantz 7 with a modern, PCB based tube amp is to compare apples with pears. They sound completely different.
Before going in a choosen direction, one should know where this path leads to.
If you have no clue about the sonic differences of tube amps, no one can help you here.
You could even choose any cheap chinese, it wouldn't matter for you because there seem to be no knowledge about what it sounds like. The differences in sound signature are so big, its unbelievable. Every one picks his sound he (or she) prefers. Thats the reason why so many are continously rolling gear, because they are searching for their perfect match. In doing this, one is learning many things. The most important is, to have a congruent argument how circuits are sounding. The more advanced can furthermore tell how parts in circuits are sounding, too. And if you are on top of the hill, like a five star guide michelin cook, you know how a special circuit will sound with a special combination of very precious parts and tubes. Without knowing that all and have no clue of what and how to achieve, your right at the base of any mountain to climb upwards. This climbing is only possible by making your own eperiences with sound. Nobody can do it for you. And even this forum can't do it. Some things in life have to be done by yourself.

As Frank Sinatra used to say: I feel sorry for people who don't drink. They wake up in the morning, and that's the best they're going to feel all day.

 

[academia50]

The search for the perfect sound, "that is equal to reality" is one of the greatest utopia, a challenge that will never have a happy ending ... that's why it is a utopia ...

How much wonderful music do we know and will never know while wasting time in search of the Holy Grail?

For this reason, I agree that this community is of solidarity help for specific problems, but when each one believes they are the possessor of the knowledge of how the whole universe works, I remind Einsten and his phrase that (they say) said before To die :

"I would have liked to be a plumber"

utopia | meaning in the Cambridge Learner’s Dictionary

" an imaginary place where everything is perfect "

 

[OldHector]

I would have liked to have been a plumber too! Great minds think alike ;-)

 

[Schmitz77]

The search for the perfect sound, "that is equal to reality" is one of the greatest utopia, a challenge that will never have a happy ending ... that's why it is a utopia ...

How much wonderful music do we know and will never know while wasting time in search of the Holy Grail?

For this reason, I agree that this community is of solidarity help for specific problems, but when each one believes they are the possessor of the knowledge of how the whole universe works, I remind Einsten and his phrase that (they say) said before To die :

"I would have liked to be a plumber"

utopia | meaning in the Cambridge Learner’s Dictionary

" an imaginary place where everything is perfect "

Isn't that communism?🙂
Btw, if one accepts that reproduced music will never be able to copy reality a big step forward has been made. I'm totally in love with my sound creating producing audio machines. Are they sounding real? Not at all, but they are able to project a window with a very nice vista on the music.

 

[academia50]

The OP isn't trying to "gild the lily", he's just trying to get it to work. Without avid DIY experience, without benefit of a signal tracer, or scope just get one new 12ax7 and put it into the various locations until you find the bum tube.

Not a bum tube? look for dirty switches. easy to clean with isopropyl alcohol and it dries quickly.

Even if it did, if you don't know how to follow the signal path, it won't do any good.....


I think you should take it to repair or buy something new.
As I already said, I go for the second option.

 

[academia50]

And has anyone seen the vintage RCA connectors ? 🙄
Current patch cords, OFC and gold-plated, won't do much good.
They will loosen ..........😱

 

[academia50]

Isn't that communism?🙂

WTF ?

 

[Duke58]

Communism- everybody is equally worthless.

 

[freddi]

Here's the trouble shooting guide from SP3A's manual. The whole manual with whatever schematic variations, bench tests, service info for SP3A is available at Hi Fi Engine - join up to have access.

Here's the address for the manual/service guide - its well worth joining Hi Fi Engine
Audio Research SP-3A-1 High Definition Stereo Control Amplifier Manual | HiFi Engine

As its early and iconic, keep it that way. It was an all out attempt for a tube preamplifier -control center. Being
old I sometimes forget how much inflation there has been since those days and how weak a USD really is - without
China we'd have nothing affordable.


And here (I made it pretty large) is the first schematic (12-24-74) from that manual - there are several
as it covers all SP3_

https://i.imgur.com/o3tNl1c.jpg

 

[Kay Pirinha]

To compare a Marantz 7 with a modern, PCB based tube amp is to compare apples with pears. They sound completely different.

Basically your statement is correct. But aren't we discussing an Audio Research SP3-C preamplifier rather than a Marantz? Did you muddle up two different threads by mistake?
What a pity the lady lives in the USA. If her offer were closer to me, I'd surely have an itch to go and haul it. What a nice device this is, and how comprehensive the documentation is that AR gave to ANY user!
Btw, I appreciate the presence of CF's all over the place, but I'd replace all 12AX7's there by tubes that are more up to task and modify the related cathode resistors. And I'd replace the RCA's by gold plated ones, the potentiometers by better ones etc. and keep the original parts in storage, should I ever need to bring the unit back to it's original estate.
Best regards!