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Marantz 8b

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mjalazard

mjalazard

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I am so happy with his work on my Heathkit AA 151
http://www.audiokarma.org/forums/showthread.php?t=550941
that I had Sam Kim work on my Marantz 8b. I have done some preliminary listening. I find this to be the most musical amplifier I have ever heard!
At 23 watts Triode, it drives my Apogee Stages (Mini Grands) with effortless detail and depth. All the positive reviews of his work are quite true. I'm having fun listening to music and hearing nuances I've never heard before.

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More reports and listening in the future.
Mike
 
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Interesting. I have no doubt that it sounds wonderful. However I do question the wisdom in doing much beyond simply restoring when it comes to such highly collectable pieces. However, perhaps with that hole in the chassis, it was actually a perfect candidate for some more extreme mods.

I find it interesting that mylar caps were chosen. They have a very distinct sonic signature. Having played with some many years ago, I found that they added a nice lush quality to the midrange at the expense of some detail and transparency, and that they also were exceptionally sensitive to fully warming-up before sounding their best.

However one thing strikes me as out of place. The mis-matched driver tubes will probably cause some strange things to happen with the stereo image. RCA Clear-tops 6FQ7s sound quite different from Sylvanias. So I'd recommend finding a matching clear-top so that you can hear how the amp really sounds now.
 
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goldear said:
Interesting. I have no doubt that it sounds wonderful. However I do question the wisdom in doing much beyond simply restoring when it comes to such highly collectable pieces. However, perhaps with that hole in the chassis, it was actually a perfect candidate for some more extreme mods.

I find it interesting that mylar caps were chosen. They have a very distinct sonic signature. Having played with some many years ago, I found that they added a nice lush quality to the midrange at the expense of some detail and transparency, and that they also were exceptionally sensitive to fully warming-up before sounding their best.

However one thing strikes me as out of place. The mis-matched driver tubes will probably cause some strange things to happen with the stereo image. RCA Clear-tops 6FQ7s sound quite different from Sylvanias. So I'd recommend finding a matching clear-top so that you can hear how the amp really sounds now.
Click to expand...
I'll do that...Thanks for the advice I'll find a pair of RCA's
I believe the holes were placed to help dissipate heat.
Mike
 
So you didn't get it like that, Sam Kim cut a hole in the chassis? This is what I'm trying to understand. Did he inform you he was doing this?

I'm thinking that a power switch was mounted in that hole and it was relocated by Sam to the front, just a guess.
 
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bktheking said:
So you didn't get it like that, Sam Kim cut a hole in the chassis? This is what I'm trying to understand. Did he inform you he was doing this?

I'm thinking that a power switch was mounted in that hole and it was relocated by Sam to the front, just a guess.
Click to expand...

Here's my guess.

Originally there were 2 gray cylinders back there, now only one. Someone repaired or modded it and got rid of the the smaller one and covered up the hole.

Here is a picture of my stock 8b.

attachment.php
 
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Sorry

I can't stomach this mod it's totally inappropriate for Marantz vintage tubes unless a rusted or cut up trashed chassis -even then........

Take no offense just my 2cents
 
Hope nothing metallic falls in that hole! I would reattach the old (empty) cap can for safety and aesthetics.

I have a stock 8B as well with 00 year production Svetlena EL34's, vintage Phillips E90F's and Rca Clear top shielded 6GC7's. My tubes don't glow blue! Bias is set correctly and it has been checked by a competent tech and found to be better than spec. Is this a photographic effect?



http://www.audiokarma.org/forums/showthread.php?t=476169
http://www.audiokarma.org/forums/showthread.php?t=480089
 
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uenjoymyself said:
I have a stock 8B as well with 00 year production Svetlena EL34's, vintage Phillips E90F's and Rca Clear top shielded 6GC7's. My tubes don't glow blue! Is this a photographic effect?

Hope nothing metallic falls in that hole! I would reattach the old (empty) cap can for safety and aesthetics.

http://www.audiokarma.org/forums/showthread.php?t=476169
http://www.audiokarma.org/forums/showthread.php?t=480089
Click to expand...
The blue glow is a photographic effect. There is a small mesh covering the holes on the chassis, so nothing will fall in.
The power switch and missing capacitor can on the base was how the 8B was configured when I first bought it. It had been modified in the past but did not sound as good as I thought it should be. I understand and appreciate those who don't like altering a vintage amplifier. I guess it is like how some folks like to hot rod a vintage car, others like to preserve the original glory.
Thanks for all your input!
Mike
 
Congrats on your Marantz 8B! I'm glad that you now have it sounding the way you want it to! Its hard to be disappointed with the 8B. It's truly one of the best sounding tube amps that I have heard.

Please know that my suggestion was just that and not a criticism.

You have a working/serviced 8B what could be finer! Enjoy!

Cheers, going to go take a pic of my tubes now. :D
 
The blue glow is NOT a photographic effect. It's a fluorescent effect exhibited by some power tubes.
 
Sam Cogley said:
The blue glow is NOT a photographic effect. It's a fluorescent effect exhibited by some power tubes.
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Ok, well, My tubes DONT glow blue to the naked eye or the camera lens. Is this any indication of their quality or performance?

My power tubes are the same as the OP's and appear to be the same as onmeug's

Thanks
 
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Read that link I posted. It will explain it.

At cold start, my Svetlana 6L6GC's will light up purdy blue but then fade away after about 10 minutes or so.
 
uenjoymyself said:
I have a stock 8B as well with 00 year production Svetlena EL34's, vintage Phillips E90F's and Rca Clear top shielded 6GC7's. My tubes don't glow blue! Bias is set correctly and it has been checked by a competent tech and found to be better than spec. Is this a photographic effect?
Click to expand...

Probably normal for later vintage SED's. They have a much higher vacuum than 00 and earlier SED tubes.
 
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