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Marantz 7 clone

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speedless

speedless

Member
Joined 2013
Hi
Just recieved this preamp:
Latest 6Z4 6N4 x3 Maratz 7 Tube Preamplifier Board | eBay
Cheap and free delivery.(7 days):)
Its suppose to be a marantz 7 updated version.
As usual the documentation from the seller is very thin.
No data,just the voltage needed.
Anyone got some info,experience on this thing ?
Diagram,data...
Unpacking impression:
The assembled board is a mixture of very cheap and some ok components.
It just begging for an upgrade.Any advice on this?

Jan
 
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SY

SY

Ex-Moderator
Joined 2002
SYclotron.com
Yes, don't build anything advertised as a Marantz 7 clone. :D The real one was not a great design to begin with, and trademark pirates on EBay are likely to have put together something that doesn't much resemble it and has design errors and reliability issues.

edit: I notice the consistent use of "Maratz" by the seller. Amusing- is that an attempt to prevent being shut down for trademark infringement?
 
kevinkr

kevinkr

Administrator
Joined 2004
kta-hifi.net
Paid Member
SY said:
Yes, don't build anything advertised as a Marantz 7 clone. :D The real one was not a great design to begin with, and trademark pirates on EBay are likely to have put together something that doesn't much resemble it and has design errors and reliability issues.

edit: I notice the consistent use of "Maratz" by the seller. Amusing- is that an attempt to prevent being shut down for trademark infringement?
Click to expand...

Agreed on all counts.. Now that you've got it though I would focus on coupling caps, and fixing any pcb errors you can identify. Many of the early ARC pre-amplifier designs were quite similar to this one, and like the 7 are not amongst the best sounding I have heard. (One can say the same for the tube McIntosh pre-amps as well.) I have trouble understanding why anyone would clone this design, a good one still manages to sound very dated. (Obviously piggybacking on the Marantz reputation, but truthfully it's their power amps that sound good, the original Marantz 1 Consolette pre-amplifier was not bad either, but no one clones it.)
 
denny9167

denny9167

Member
Joined 2007
kevinkr said:
Agreed on all counts.. Now that you've got it though I would focus on coupling caps, and fixing any pcb errors you can identify. Many of the early ARC pre-amplifier designs were quite similar to this one, and like the 7 are not amongst the best sounding I have heard. (One can say the same for the tube McIntosh pre-amps as well.) I have trouble understanding why anyone would clone this design, a good one still manages to sound very dated. (Obviously piggybacking on the Marantz reputation, but truthfully it's their power amps that sound good, the original Marantz 1 Consolette pre-amplifier was not bad either, but no one clones it.)
Click to expand...
:D:D home run!!
 
kevinkr

kevinkr

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The second one is even worse, there is a serious issue with the output stage, that can't be right.. lol Of course the OLG is high enough that you can fix almost anything bad inside the loop. (Wondering if that is a misdrawn WCF)

OLG in these designs is ridiculous, I measured > 4000 in one instance or >72dB which leaves you with a huge feedback margin and some potential stability problems if you are not very careful. I've heard a few clones over the years, my recollection is the best one was just OK, nothing thrilling about it.

The 6N4 incidentally is a domestic Chinese equivalent to the 12AX7A.

Long ago (1988) when I finally started to build tube audio gear from scratch I cloned the line section of an ARC SP-3 excluding the tone control section and reduced the CLG from 34dB to 26dB. I was very disappointed with the performance, it sounded horrible imho and I then embarked on my own design. Strangely enough I did not clone the phono stage because I did not have the right value caps for the EQ, I did have the right values for a passively equalized phono stage which I designed and actually sounded quite decent except for being excessively noisy for use with some lower output MM cartridges. lol
 
kevinkr

kevinkr

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Who is?

I'm not aware of a vintage model 7 power amp from Marantz, can you point to a link?; I am aware of Model 2, Model 5, Model 8, Model 8A, and Model 9 power amplifiers and have worked on all of them in the now rather distant past. :)

I'm also very familiar with the Model 7 pre-amp (C designation just stands for 'cabinet') and never found it particularly thrilling. Very dated and veiled sounding compared to a lot of things I've heard. One passed through my hands a couple of decades ago and despite its excellent condition I found it very underwhelming, had the reverse been the case I would have kept it.
 
D

DAK808

Member
Joined 2012
I got to rebuild a Marantz 7 preamp some years ago and so i had it in my system for about a week while the parts broke in and i did sound and voltage checks. The sound was nice and warm perhaps a little better than the other preamps of their era. But i dont think anyone would make a preamp like that unless you were looking for a "vintage sound" or needed the tone controls. BTW, did you know the power supply in the 7 is just half wave rectified. I was kinda shocked by that. best regards
 
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