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Marantz 8B

C

cholopa

New Member
Hello:

I own (as a lagecy from my father) two Marantz 8B and one preamp Marantz 7T.

Apart from minnor problems they are all in good shape :banana:

I know my father puted the 8B's in mono and then again in stereo mode.

Now i would like to put then again in mono mode to use both of them at the same time, but i am not sure of what wires should i join or separated.

Can someone please tell me what should i do?

I have included here a photo form a Marantz 8B in case is helpfull . The photo is not mine it is taking from aanother post in this forum.

Marantz8B_HRV2.jpg


regards, and thank you for your time.
 
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You lucky devil, take good care of those 8s, and enjoy them to the fullest. :yes: As far as the wiring goes, I'd need to look at a schematic, but I'm sure more knowledgeable members will chime in. You may want to recap your 8s before putting them into regular service, if this has not been done previously. Have fun above all else.

BTW, welcome to AudioKarma!
 
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I'm not sure if they are capable of being bridged to mono, but any mono/stereo selection would have been done by the preamp.

You can't really tell by the photo if they are wired to mono.

What I think you are asking is if each amplifier can be bridged to mono meaning that each amplifier would be able to drive one speaker so two amplifiers make stereo.

I am not familiar with the 8B, so I don't know if they can be bridged to mono or not. Someone else here may have your answer.
 
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century tek said:
What I think you are asking is if each amplifier can be bridged to mono meaning that each amplifier would be able to drive one speaker so two amplifiers make stereo.
Click to expand...

Yes, that is what i intended to mean, sorry for my bad english.
 
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cholopa said:
Thanks for your welcome autoanalog :thmbsp:

I don't fully understand you message, (sorry i'm not english). By "recap" do you refer i should change the capacitors like this guy:

http://forums.klipsch.com/forums/t/153822.aspx?PageIndex=1

Or the tubes (EL-34, KT-77..etc)?

Thanks for your time.
Click to expand...

Absolutely! I'm happy to help a fellow classic Marantz owner in any way I can. My apologies for the jargon, I meant replacing the electrolytic as well as the paper and oil-type capacitors is highly recommended. Congratulations upon your inheritance, a similar event happened to me recently.
 
They are easily bridged. Here is how the manual says to do it: (see attachment)

Lou
 

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  • 8bman-2.jpg
    8bman-2.jpg
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Thank you very much for your help :thmbsp:

If i understand well, i just need to "divide" the signal in two at the input and converge it again at the output (taking care of the ohm of the speaker).

I think i'll do it outside, so no modifications made in the inside.

Thanls very much again :D
 
Glad you were able to get the information you wanted, Cholopa.

The pictures are excellent. I would like to point out that the amps you have appear to be just as they were when they were new. If you spend some time here and at some of the other audio forums, you will find that having the amps worked on to replace some parts (capacitors mainly) that have grown old and will no longer operate as they should and with safety. This effort is typically called, "recapping".

There is a bit of a debate about this, however, as to what, exactly, to replace. Just know that a good bench technician should understand what needs doing. They should know something about Marantz tube gear, however, to understand how to do this.

Good luck with them. I understand that these amps mean more than just the collector value to you. I, too, have 2 pieces of McIntosh gear given to me by my step-mother-in-law. They have been restored and now reside here beside me and operate almost daily.

Cheers,

David
 
The capacitors with color stripes are always bad - electrically leaky - and may cause damage to other parts if you power it as-is. Other ones MIGHT be OK, but it may be easier to replace them all.
 
If you do service the amps, save all of the parts that you replace. Collectors will pay much more for an original amp than one that has had the parts changed. If you ever go to sell it you will be happy that you can return it to 'original' condition.
 
Thanks all for the information.

The photo is not from one of my Marantz 8B ( i found it on this forum), but mine are in (more or less) the same condition (maybe a little more dirty).

By now i am quite afraid of changing anything by myself, and i not too sure that anyone in Spain has the right knoledge to do it, so i think i'll keep them the way they are, at least for the time been.

I have bought a couple of things at ebay(cables, RCA..etc), to make the stereo to mono mod. I can't wait to try it all :-)

By the way i need a fusefolder for one of the marantz amp. I found this guy:

http://timeless-audio.com/svcdept.html

But he doesn't seem to sell outside USA.

I also found this guy:

http://www.ebay.com/itm/Marantz-Fus...ctronics_R2&hash=item4cfc00b04b#ht_500wt_1029

But i think the price is totally mad, do you know any other place where i can get it?

Thanks for you time,

regards,
 
The picture is from one of my Marantz 8B's. A unit from 1964 that worked perfectly well with the old caps in there. Only replaced the selenium bias rectifier with a 1N4007 equivalent and it was good to go.

With these units, wholesale replacement of caps is definitely detrimental to the sound, and of course, the collectability.

Replace only what's bad. The electrolytics in the power supply are extremely long lived as they were designed for the telephone industry. The Good-All caps are mylar and dipped in epoxy, again, they rarely go bad.

The fuseholder is a standard type, not unique to Marantz. Easy to source, even today.
 
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