This is a test to determine any interest before I dig in. Quite frankly, I’m scared.
I aquired the top-of-the-line pair of 1970’s Audio Research of 75 watt/chn amplifier and control amp (preamp), and wondered if there was any interest in buying them together before I try to restore them. Please PM your interest, if so I would be willing to take off the covers and take pictures as you like.
They both come with original small tubes (Telefunken small tubes, Amperex, etc. - I will not check now, unless serious interest, because of the substantial perforated covers), but the pair was running before it was decommitioned. The previous owner did mention a power amp hum, before taking it out of service.
They are complicated Hi-fi pieces and I would not like to mess this up, hence the offer.
On Diyaudio.com there are very detailed accounts of restoring both these prime vintage pieces, if you needed any help. This restoration is not for the casual tube amp builder. But according to experience produce top-of-the-line results, even by todays standards.
Please PM me with any interest or offers.
I aquired the top-of-the-line pair of 1970’s Audio Research of 75 watt/chn amplifier and control amp (preamp), and wondered if there was any interest in buying them together before I try to restore them. Please PM your interest, if so I would be willing to take off the covers and take pictures as you like.
They both come with original small tubes (Telefunken small tubes, Amperex, etc. - I will not check now, unless serious interest, because of the substantial perforated covers), but the pair was running before it was decommitioned. The previous owner did mention a power amp hum, before taking it out of service.
They are complicated Hi-fi pieces and I would not like to mess this up, hence the offer.
On Diyaudio.com there are very detailed accounts of restoring both these prime vintage pieces, if you needed any help. This restoration is not for the casual tube amp builder. But according to experience produce top-of-the-line results, even by todays standards.
Please PM me with any interest or offers.
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You should list the exact model of the preamp, SP-3, SP-3A, or SP3A-1.
Do you have the original shipping cartons? That is very important.
If not, you will have to buy new boxes from Audio Research in order to
ship them safely.
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Good points! This is indeed a SP-3 as listed in the topic line. No original boxes.
More details on the SP-3
I took down and opened up the SP-3 control amplifier.
As can be seen in the photos, it is in very good physical shape. No dents or scratches. It is a bit dirty and dusty. I don’t know easily the “dirt” will come off the faceplate left-side, but I used a soft sponge and wiped the volume knob and the dirt is beginning to come off it. The eight 12ax7 tubes are all Amperex made in Great Britian.
I have not tried to power it up - I think the new owner would want to reform the capacitors before bringing it up gently. The previous owner assured me it worked well before taking it out of commision. So, I can not guarantee it will work, I have reason to believe it will.
For price, I’m looking for offers around $600 for the SP-3 including tubes, $500 without. Buyer pays shipping, if not local pickup. Two people who sent PM to me have first option.
Similar information to follow on the D-76A power amp, planned tomorrow.
I took down and opened up the SP-3 control amplifier.
As can be seen in the photos, it is in very good physical shape. No dents or scratches. It is a bit dirty and dusty. I don’t know easily the “dirt” will come off the faceplate left-side, but I used a soft sponge and wiped the volume knob and the dirt is beginning to come off it. The eight 12ax7 tubes are all Amperex made in Great Britian.
I have not tried to power it up - I think the new owner would want to reform the capacitors before bringing it up gently. The previous owner assured me it worked well before taking it out of commision. So, I can not guarantee it will work, I have reason to believe it will.
For price, I’m looking for offers around $600 for the SP-3 including tubes, $500 without. Buyer pays shipping, if not local pickup. Two people who sent PM to me have first option.
Similar information to follow on the D-76A power amp, planned tomorrow.
Sorry, but other things took over today, Friday.. I now plan to post pictures of the D-76A tomorrow, Saturday.
Pictures of the D-76A
After opning it up all looks well. No burns, fires etc., etc. The small tubes are all Amperex 12AX7s and the General Electronics 6FQ7/6CG7 as per specifications, except one, which is a RCA.
See picturess following.
First the outside paapearance.
After opning it up all looks well. No burns, fires etc., etc. The small tubes are all Amperex 12AX7s and the General Electronics 6FQ7/6CG7 as per specifications, except one, which is a RCA.
See picturess following.
First the outside paapearance.
Attachments
Hello Francois,
Thanks for the transaction. I dug into the SP-3 last night and found 3 of a total 13 bad PS diodes. If that is it I will be quite happy (actually happy anyway), and look forward to listening to it in my system, which currently has a 6H30 based Broskie Aikido.
The D-76 is next - hopefully sometime this weekend.
Thanks again for meeting up with me on a workday.
Thanks for the transaction. I dug into the SP-3 last night and found 3 of a total 13 bad PS diodes. If that is it I will be quite happy (actually happy anyway), and look forward to listening to it in my system, which currently has a 6H30 based Broskie Aikido.
The D-76 is next - hopefully sometime this weekend.
Thanks again for meeting up with me on a workday.
Thanks for the feedback. I am sorry you found bad diodes in the SP-3 (I did not expect that), but I’m also pleased that you identified a problem - hopefully the only one with that item.
When you “dig into” the D-76A, may I suggest you reform the caps slowly, in case they are still serviceable? Keeping fingers crossed.
There is a thread on diyAudio of a tech-guy refurbising the D-76A which you may find interesting, including his recommendations of big caps to replace the twist-lock ones. His article was done a few years ago, when I searched Digi-key I thought there were better choices now.
When you “dig into” the D-76A, may I suggest you reform the caps slowly, in case they are still serviceable? Keeping fingers crossed.
There is a thread on diyAudio of a tech-guy refurbising the D-76A which you may find interesting, including his recommendations of big caps to replace the twist-lock ones. His article was done a few years ago, when I searched Digi-key I thought there were better choices now.
Hello Francois,
Replace the dead diodes in the Pre and she is up and running - pretty quiet for being 45 years old.
The Tone section still needs work (does not come on), but I can wait to fix, as I don't use / need the Tone changes...sounds nice.
The amp was cleaned up, and re-biased, and one channel a little noisier than other - but plan on replacing all output tubes (currently a mismatch of two different matched 6550 types). I just ordered new bulbs and with those corrections, the amps should be good to go. Again, pretty quiet for being 45 years old.
I also cleaned them up a bit - all the goop and white splotches - pretty nice looking matching setup now. Should go great with my Magnepan MG3.5R....more later, including pics..
Also, could not find the posting on DIYAudio on reforming caps in a D-76A...if you find it, can you post it for me? Thanks again.
Replace the dead diodes in the Pre and she is up and running - pretty quiet for being 45 years old.
The Tone section still needs work (does not come on), but I can wait to fix, as I don't use / need the Tone changes...sounds nice.
The amp was cleaned up, and re-biased, and one channel a little noisier than other - but plan on replacing all output tubes (currently a mismatch of two different matched 6550 types). I just ordered new bulbs and with those corrections, the amps should be good to go. Again, pretty quiet for being 45 years old.
I also cleaned them up a bit - all the goop and white splotches - pretty nice looking matching setup now. Should go great with my Magnepan MG3.5R....more later, including pics..
Also, could not find the posting on DIYAudio on reforming caps in a D-76A...if you find it, can you post it for me? Thanks again.
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