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Marantz Model 7 Build

abartee

abartee

New Member
I have fond memories of my first nice system in the late 70's that included a Mcintosh C22 but got rid of it in the 80's due to big dose of stupidity. My desire is to build a scaled down version of the Marantz model 7 using the layout posted by Chris Ruggiero at Preservation Sound but want to include the real model 7's stepped tone controls and output level trim pots minus the high and low filters. What I'd be grateful for is to have someone with more tube building experience than I look at a section (line stage side) of the original model 7 schematic that I've drawn a circuit path around the two filter sections (blue lines) and let me know if the bass and treble controls plus trim pots would have a chance of success being inserted between triode 5 and cathode follower triode 6 in Chris's scaled down version. Please see both schematics attached. Thanks in advance!

model 7 forum 2.jpg marantz7c-1024x801.jpg
 
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The place you have chosen appears to be the right place in the lineup. This appears to be your first message on AK, so welcome to Audiokarma! The Marantz model 7 is a beautiful piece of HiFi history, and commands a very high price. I also elected to build my own preamp rather than spend top dollar for a box of "classic" used parts. So I'd say you are on the right track and making sound decisions. No pun intended.... I know nothing of your past workmanship or experience level, but suffice to say, a full on Marantz model 7 clone, may not be the best place to start your journey into Diy tube HiFi. I'm not saying don't do it, but don't bite off more than you can chew. If this is your first DIY project please consider building a few cheaper and simpler kits,before tackling this epic project. I think a modern M7 clone is a great idea and I've even kicked around the idea of building one myself, but I'm not there yet.

Welcome to AK.
 
Thanks for the warm welcome! I was considering looking for a "needs work" model 7 but as you stated, you would then be faced with renovation which can get very expensive on top of the several grand just spent.
I've fortunately been tinkering with electronics projects all my life and have built a scratch built tube line stage successfully over the last two years which came out dead quiet. Although, I realize that successfully taming grounding issues and noise with phono stages presents a whole new level of challenges but I want to plunge ahead and see if I'm up to it!
Thanks for looking over the circuits. What I'd like to do is go ahead and put together a composite sketch of the scaled down version with the addition of the tone controls and will post to see if things look in order.
 
M7 scaled down plus tone and trim pots.png I had difficulty trying to put together a composite drawing of the scaled down M7 from Preservation Sound with tone controls and trim pots from original Marantz schematic added back. The resulting drawing is less than optimum but shows the general scope of changes. I would be grateful if someone could critique the circuit and give feedback as to any changes needed.

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