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Audio Research SP3a

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#5
planet10 said:
I built an SP3a clone in the mid 70s (sold them too). Very nice chassis. The best mod would be to strip it and start over....

<snip>

dave
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I too made that mistake in the late 1980s.. 😱😛

FWIW I agree with Dave, probably pass this along to a collector and build yourself an Aikido, one of mine, or anything else you fancy..

The design and its performance really leaves a lot to be desired by today's standards. And I'm NOT trying to be mean.. I was very disappointed.
 
#7
I'm not really an expert at electronics. (I'm actually a car mechanic.) I just finished rebuilding my old Dynaco Mark VI's. I mean yesterday was the first time I could listen to both amplifiers. I simply can't afford to give AR $1300 to upgrade the preamp. I did replace the coupling caps with Solen polypropylene ones. That seemed to help. I'm also told that the slight harshness in the upper midrange lower high frequencies is caused by the nickle plated RCA jacks. Does that sound plausible? I've ordered gold plated ones.

I looked at the Aikido. Do you really think it would be better to start from scratch? In that case what I would like is a really sweet sounding tube preamp kit. With an input for my CD player and a phono preamp. An on/off switch and a volume control and nothing else. Is there such a kit? At a reasonable cost?
 
#8
I have little doubt even an RCA phono (as modded by Eli) followed by a 12B4 (or an ECC88 CC DC coupled to CF -- you'll find that buried in the SP3A) would smoke the SP3A.

How good it can be comes down to power supply execution and how well matched you can get the EQ in the RIAA.

And there are lots of other great choices.

dave
 
#10
Common Cathode DC coupled to Cathode Follower.

Here. Snipped from the SP3A schema... be better with a CCS (constant current source) on the bottom of the CF.

(ECC88 = 6DJ8)

dave
 

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#11
mr2racer58 said:
I'm also told that the slight harshness in the upper midrange lower high frequencies is caused by the nickle plated RCA jacks. Does that sound plausible?
Click to expand...

No. The issues with the SP3A are in the topology- a strip and rebuild would be needed to make it into a first rate unit. If you love the look and feel, that's the way to go. If not, I'd concur with the notion of selling it and building something from scratch. The Aikido is one of several good choices.
 
#12
I can follow a schematic. But I can't design a circuit. So if there were a schematic to rebuild the SP that would be nice. But the Aikido seems like about $200 or so plus the box is that right? Is there a complete kit available?

My SP is working fine right now but I know the power supply caps are thirty years old so I'm on borrowed time here.
 
#17
So now I'm stuck with the decision to sell the preamp and build something from scratch. Or modify the amp I have. I checked out Joe Curcio's upgrade. Has anyone heard this version? Calvin at AR says the SP3c is comparable to a an LS 16. Does that sound right?

I haven't totaled it up yet but it seems the parts for Joe's upgrade would have to be more than an Aikido?
 
#18
mr2racer58 said:
So now I'm stuck with the decision to sell the preamp and build something from scratch. Or modify the amp I have. I checked out Joe Curcio's upgrade. Has anyone heard this version? Calvin at AR says the SP3c is comparable to a an LS 16. Does that sound right?

I haven't totaled it up yet but it seems the parts for Joe's upgrade would have to be more than an Aikido?
Click to expand...

No idea, but I would take that claim with a big grain of salt. (And.. I suspect there are plenty of higher end diy efforts that probably sonically outperform anything ARC has to offer whether treated to expensive parts upgrades or not.)

I think the Aikido is a much better expenditure of funds and would allow you to sell that unsullied SP3A for very good money when the market picks up hopefully by summer's end. (You might consider putting this on Audiogon instead of eBay, much cheaper and sometimes more successful too.)

Note:

AR "Acoustic Research" http://en.wikipedia.org/wiki/Acoustic_Research The current company using this name today has little to do with the original company.

ARC "Audio Research Corp." (the maker of your pre-amp)

Is the AR you refer to some third party or in fact ARC?

AR Cambridge AKA ARCAM - UK audio firm unrelated to either of the above.
 
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#20
Hello MR2,

Surely you can build an Aikido preamp inside the Dynaco PAT4 chassis. It just matter you have to check whether the size of the PCB can be fitted inside. If not, you may have to consider to build it without the PCB that would save a lot of space in there.

The power switch, volume and input selector can be used. Tone control?? - no no.


Johnny
 
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