Hey folks,
I Picked up a NS-10 preamp, two M1s, 400a and a Cas-2 all for $650.00 All of this stuff is original and in good working condition. All they need is the electrolytics replaced and some minor repairs.
I have a few questions:
NS-10:
1) The NS-10 had the transformer replaced with, I'm told, one that is of the same specs. I see that the original one manufactured by Signal transformer DPC-24-450 is still available from Digikey. If this is not the transformer in there, should I replace it again with the correct one, or is there any benefit to going with a higher VA rated toroidal type?
2) How well will this preamp NS-10 mate with the "First Watt" F5 which I intend to build?
400A:
3) The 400a is very nice, but, has the wrong feet and the front panel bolts are missing. Where can I get the original (4) bolts?
4) The 400a has very good condition original emiter resistors. I just did a total rebuild on another 400a that was totally destroyed and all the emitter resistors were split or broken. I would stay with these original resistors if I were keeping the amp. I loaned my son the 400a I rebuilt and will swap it back with this one as the rebuilt one is of my best work and what I consider "show quality". I'm concerned about the original emitter resistors, as, my son is running low impedance Magnepans. Should I change them?
M1s:
1) The seller told me one of the M1s did not sound as good as the other and he thought there might be a problem with it. It doesn't have much circuitry in it to fail. Is there a comon failure with these? Should I replace the Tantalums? My understanding is that, Tantalum caps don't fail due to age. Is that correct?
CAS-2
Comment - All I can say, is, I never knew this amplifier existed. What a great amplifier it is! This thing is very well made and sounds great!
I'm attaching photos of my 400a rebuild and all the great vintage NP stuff I just picked up. I have some cool fix's for the 400a in the photos you might like. The rebuilt 400a says "cascode" on the glass and the 400a I just picked up does not. Is the one without "cascode" not printed on the glass different, or was it just printed on the newer models?
Gary
I Picked up a NS-10 preamp, two M1s, 400a and a Cas-2 all for $650.00 All of this stuff is original and in good working condition. All they need is the electrolytics replaced and some minor repairs.
I have a few questions:
NS-10:
1) The NS-10 had the transformer replaced with, I'm told, one that is of the same specs. I see that the original one manufactured by Signal transformer DPC-24-450 is still available from Digikey. If this is not the transformer in there, should I replace it again with the correct one, or is there any benefit to going with a higher VA rated toroidal type?
2) How well will this preamp NS-10 mate with the "First Watt" F5 which I intend to build?
400A:
3) The 400a is very nice, but, has the wrong feet and the front panel bolts are missing. Where can I get the original (4) bolts?
4) The 400a has very good condition original emiter resistors. I just did a total rebuild on another 400a that was totally destroyed and all the emitter resistors were split or broken. I would stay with these original resistors if I were keeping the amp. I loaned my son the 400a I rebuilt and will swap it back with this one as the rebuilt one is of my best work and what I consider "show quality". I'm concerned about the original emitter resistors, as, my son is running low impedance Magnepans. Should I change them?
M1s:
1) The seller told me one of the M1s did not sound as good as the other and he thought there might be a problem with it. It doesn't have much circuitry in it to fail. Is there a comon failure with these? Should I replace the Tantalums? My understanding is that, Tantalum caps don't fail due to age. Is that correct?
CAS-2
Comment - All I can say, is, I never knew this amplifier existed. What a great amplifier it is! This thing is very well made and sounds great!
I'm attaching photos of my 400a rebuild and all the great vintage NP stuff I just picked up. I have some cool fix's for the 400a in the photos you might like. The rebuilt 400a says "cascode" on the glass and the 400a I just picked up does not. Is the one without "cascode" not printed on the glass different, or was it just printed on the newer models?
Gary
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You can't go wrong with the original Signal transformer.
And you know that it will work properly. What's not to like?
And you know that it will work properly. What's not to like?
Ooops, The "First Watt" amplifier I want to build is the "F4" not "F5". How well will the NS-10 preamp work with the "F4"?
Hi Rayma,
I restored and updated a Superphon Revelation Basic preamp for my son and in the upgrades reommended by Stan the original designer was a much larger toroidal transformer. These transformers were not poular in the 70's like they are today.
Gary
I restored and updated a Superphon Revelation Basic preamp for my son and in the upgrades reommended by Stan the original designer was a much larger toroidal transformer. These transformers were not poular in the 70's like they are today.
Gary
Glad it worked out.
I'm not a fan of making unproven changes in the Pass design, though.
Or drilling extra holes in the chassis, etc.
I'm not a fan of making unproven changes in the Pass design, though.
Or drilling extra holes in the chassis, etc.
Hi rayma,
I agree, I don't make changes that are not reversible. The guy put holes off the 4 corners of the transformer on the PCB to accommodate two tie wraps. I don't believe there is any traces there but still unfortunate.
Gary
I agree, I don't make changes that are not reversible. The guy put holes off the 4 corners of the transformer on the PCB to accommodate two tie wraps. I don't believe there is any traces there but still unfortunate.
Gary
Hi rayma,
The transfomer was a drop in replacement. He added the tie wraps to further secure it. He said that it broke off but there is no damage to the chassis from impact. I think I looked at him like he had two heads. I said, what? you replaced the transformer??? Anyway, the holes are clean and look factory. I had to view several photos of other units to verify that they were not.
Gary
The transfomer was a drop in replacement. He added the tie wraps to further secure it. He said that it broke off but there is no damage to the chassis from impact. I think I looked at him like he had two heads. I said, what? you replaced the transformer??? Anyway, the holes are clean and look factory. I had to view several photos of other units to verify that they were not.
Gary
I searched Youtube for a video of this amp and there are none. Maybe, I'll post mine. The seller said he bought the 400a and decided he liked the Cas-2 better and put the 400a on the shelf and never looked back.
Yep, I'll know more when I get into it for a re-cap. Right now, I'm just enjoying listening to it. I plan to just replace the aluminum electrolytics. I really like the low ESR Panasonic "FR" variety.
Thanks, It was a fun project and my first Threshold. I always wanted one. When I was way younger, I had to choose between buying a Nakamichi PA7 or the Yamaha M85. I cheaped out and got the Yamaha. I don't regret it, but still would like a PA7.
Well, you're in the right place, with the man himself available for input.
I have a feeling I was way younger when you were way younger. Back in the day, looking at a Nakamichi TA4 I was talked into a back-door deal on a modded Hafler, which thirty years later brought me to DIYaudio to repair/ rebuild based on the Bob Cordell design, and suddenly I'm in Nelson's back yard and have now built some of my dreams, i.e. the Aleph 60s...
And yeah, there's a CA5 and a PA5 in the house, serving daily duty. Listening to the PA5 right now, as a matter of fact as the kids have the Alephs in the family room serving up the incredible sonics of Lego Lord of the Rings games.
My brother lives and dies by his PA7 and his collection of PA 5s, Pa5-2s (though I lent him an Aleph J and he's getting it). PA7s, last I checked, were running $1500 or so. So, for the price of building my own amps, I could have a PA7... but there's joy and pride in building your own and doing what you've done, which is rescue a piece of history.
Good on you!
I have a feeling I was way younger when you were way younger. Back in the day, looking at a Nakamichi TA4 I was talked into a back-door deal on a modded Hafler, which thirty years later brought me to DIYaudio to repair/ rebuild based on the Bob Cordell design, and suddenly I'm in Nelson's back yard and have now built some of my dreams, i.e. the Aleph 60s...
And yeah, there's a CA5 and a PA5 in the house, serving daily duty. Listening to the PA5 right now, as a matter of fact as the kids have the Alephs in the family room serving up the incredible sonics of Lego Lord of the Rings games.
My brother lives and dies by his PA7 and his collection of PA 5s, Pa5-2s (though I lent him an Aleph J and he's getting it). PA7s, last I checked, were running $1500 or so. So, for the price of building my own amps, I could have a PA7... but there's joy and pride in building your own and doing what you've done, which is rescue a piece of history.
Good on you!
Beautiful cleanup and repair work on the PCBs. What are all those little RF-looking finger trace things on it, do you know?
Nice to have a collection of Nak's. I have two AV10's (not a N.P. design) and a OMS 7 cd player. I have a massive collection of Celestion SL line of speakers. I have the whole line plus the 100, 300 and the System 6000. As a kid, I couldn't pass by a broken TV on the side of the road. I would repair it and sell it. As a challenge, I went around to all the TV shops and took in all the stuff they couldn't fix, then, go back and tell them what was wrong with it. I love to buy all the audio equipment I dreamed of, (broken), and restore it for friends & family.Well, you're in the right place, with the man himself available for input.
I have a feeling I was way younger when you were way younger. Back in the day, looking at a Nakamichi TA4 I was talked into a back-door deal on a modded Hafler, which thirty years later brought me to DIYaudio to repair/ rebuild based on the Bob Cordell design, and suddenly I'm in Nelson's back yard and have now built some of my dreams, i.e. the Aleph 60s...
And yeah, there's a CA5 and a PA5 in the house, serving daily duty. Listening to the PA5 right now, as a matter of fact as the kids have the Alephs in the family room serving up the incredible sonics of Lego Lord of the Rings games.
My brother lives and dies by his PA7 and his collection of PA 5s, Pa5-2s (though I lent him an Aleph J and he's getting it). PA7s, last I checked, were running $1500 or so. So, for the price of building my own amps, I could have a PA7... but there's joy and pride in building your own and doing what you've done, which is rescue a piece of history.
Good on you!