Twin MC75 refurb project next.
- Thread starter Pio1980
- Start date
Pio1980
AK Member
After a series of interruptions brought by misfortune and illness I'm trying to get this project back on track. I have both amps' circuitry renovations done and have been bench-testing them for clean output and symmetry, finding all related problems being solvable with tube replacement to restore proper operation at this point, I've already had one Electro-Harmonix 6550 go 4th-of-July. I have one amp basically ready to finish and the other still down a bit at clipping, probably more tired tubes.
Pics to follow.
Pics to follow.
Pio1980
AK Member
I replaced the BBs that see significant offset voltage across them, not those where slight leakage would have no effect on the operation of the amp. I left the input BBs as-is as the system won't put significant amounts of DC into them. The new disc caps you see are safety types to replace the BBs in the PS. I doubled up some 0.1/600V film caps I had on hand to replace the 0.22 BBs as this is a freebie for the owner and my OOP expenses are on me. Likewise for culling his used tube stash to get them to work properly, I swapped several of the smaller tubes to get symmetry and there was one very bad 12AT7 to replace. It was a job to get 2 pairs of similar KT88/6550 that would make full power and clip symmetrically, lost one that self-destructed during run-up. He has a couple more pairs in stock that are usable but don't make full power at symmetrical clipping, one of these pair are Brit made Genelex Gold Lions that will probably be sold to fund modern replacements if needed.
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Pio1980
AK Member
They are not on the shelf hooked up yet, the main system is being driven by the MC240 I previously rebuilt and put back into play. That sounds pretty darn good now.
http://mail.audiokarma.net/forums/showthread.php?t=547934
The rest of the system is early1970s self- built multi-Bozak driver towers, a Mac C24 preamp that I rebuilt first, a dvd digital media player, an H-K tuner I donated to stand in for the non functioning MR71. Once the twins go back, the 240 will return to driving Heathkit rear surround speakers driven from a Shure Surround processor. There is also a Thorens TD-125/SME 3009 turntable but that will stay out of use as its disabled 87 year old owner can no longer deal with it.
Here is the system as it was when I started, it had become totally derelict and silent.
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http://mail.audiokarma.net/forums/showthread.php?t=547934
The rest of the system is early1970s self- built multi-Bozak driver towers, a Mac C24 preamp that I rebuilt first, a dvd digital media player, an H-K tuner I donated to stand in for the non functioning MR71. Once the twins go back, the 240 will return to driving Heathkit rear surround speakers driven from a Shure Surround processor. There is also a Thorens TD-125/SME 3009 turntable but that will stay out of use as its disabled 87 year old owner can no longer deal with it.
Here is the system as it was when I started, it had become totally derelict and silent.
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Pio1980
AK Member
Here they are all back on the shelf and working fine so far. The twin 75s are the front main amps for his self-built towers and the 240 is for the side fill surround EMI speakers.
I have omitted the turntable and tape/ tape control facilities as irrelevant to the owners present requirements and for simplification of operation for the caretaker, also the surround processor and EQ. The sources of present interest are the DVD media player, the H-K tuner I brought to replace a nf MR71, and the TV cable box stereo sound output.
The system seemed to gain some SQ when the twins went in place of the 240 on the front and then things really got interesting when the 240 went back to the surround fills. It's now a big clean 'fun' sounding set-up that really fills the room without overwhelming it, the caretaker described the sound as "delicious". The resident owner is very pleased and effusive with his gratitude for the restoration of one of his major pleasures.
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Pio1980
AK Member
Well, after 15 months of interrupted visits and work both systems are now making reliable sweet music at last for this fine deserving gent and I am done and out. I will very much miss my purposeful visits with him tho have his open invitation for return social calls whenever convenient for us both.
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Pio1980
AK Member
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Pio1980
AK Member
Thankyew!
FWIW the greatroom/music room system downstairs from the mancave/bedroom got my Adcom GFA-535 and a passive level control to replace the ailing MX-110 and Altec 1590C rack amps+Soundcraftsman EQ, because it was all the room needed to play the speakers well off a CD player and it sounded real good with the simplified rig. He likes it now and that's what matters, he can sell off the other stuff if he wants.
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Pio1980
AK Member
FWIW, here is a good article on the gent that owns this system;
http://dobywood.com/FoxTheatreAtlanta/JoePattonBiography.html
His Rolls-Royce P-3;
http://dobywood.com/FoxTheatreAtlanta/JoePattonBiography.html
His Rolls-Royce P-3;
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Pio1980
AK Member
Knowing him, they may all be Bozak, I'll try to remember to ask next visit.
The tweeters appear to have metallic diaphragms.
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Pio1980
AK Member
FWIW, here is a good article on the gent that owns this system;
http://dobywood.com/FoxTheatreAtlanta/JoePattonBiography.html
His Rolls-Royce P-3;
Many folks equate fine audio reproduction to fine cars, Mr. Patton likewise with his choices of McIntosh and 1937 Rolls-Royce Phantom-III. For those of you following my related threads and interested in the owner, I have recently visited him, and while at 87 he is slowing down he still enjoys his music and both systems are still performing to our high standard. During these visits, besides chatting and music, I also endulge his other passion for fine cars via a tablet and the internet and youtube vids. The most remarkable coincidence occurred on the last visit when after some Jay Leno and other vids I took a pot luck shot and selected a movie of a 1994 90th anniversary commemorative tour of England and related sites by a Rolls-Royce owner's enthusiast group, "Rolls-Royce, In Pursuit Of Perfection".
Imagine our suprize to find that this was the tour of a lifetime he himself had attended 20 years previous with his P-III, he is the gentleman from Atlanta, "Uncle Joe", with his young nephew.
Sometimes serendipity is spot-on, and Uncle Joe greatly enjoyed reliving his experience as someone my own age, frozen in time as a younger and more vigorous man.This will stay on our hit list for future visits.
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Pio1980
AK Member
A heartbreaking update a couple weeks after one of the 'twins' quit working.http://m.wsbradio.com/news/news/local/phantom-of-the-fox-theatre-dies/nq2d7/
Thursdays were always reserved for him whenever possible, yesterday bedside with his family and friends was the last. I'm going to miss them with him gone more than I can say.
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Very sorry for the loss of your dear friend Steve, days like this are hard. I lost my oldest sister March 16th, so Im right there with you buddy. As we keep getting older we have more and more days like this. All we can really do is reflect on all the good times that have past, holding them dear to hearts.
