• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Marantz preamp clone for newbie?

I'm thinking about getting one of the diyclub marantz style preamp boards http://eshop.diyclub.biz/product_info.php?cPath=149_106_86&products_id=120

With the regulators and time delay, etc. - looks like a pretty good choice for a tube neophite. (I've built amps and speakers from kits, I'm hoping this is similar complexity.)

The circuit looks enough like the 7c that I'm hoping to try some of the classic POOGE mods later.

Are there better choices I haven't noticed? Anybody have any experience modifying these?

Thanks,
Kirk

PS - yes, I know it's not really a clone.
 

Brett

Member
2002-01-07 6:02 pm
vintagekirk said:
Are there better choices I haven't noticed? Anybody have any experience modifying these?
Yes. I owned an original 7C and modified the hell out of it before restoring it and selling it.
Build something else. Not a very good preamp, highly over-rated by the nostalgia and collector crowd. And certain segments of the Asian 'phile crowd.
The circuit looks enough like the 7c that I'm hoping to try some of the classic POOGE mods later.
Been there done that. Silk purse, sows ear and all that.

Even at it's best, it has a fat, round, cliched 'tubey' radiogram sound, with poor noise and resolution.
 

Brett

Member
2002-01-07 6:02 pm
kmtang said:
I am just wondering what's your choice of the line amp?
Do a search for 12B4a and you 'll find a bit of discussion on it.
Another interesting design would be John Broskie's Aikido. I haven't built it though.
Then there's Franks' linestage (do a search), and Allen Wright's designs (these are superb).....
kmtang said:
Then, you can get the best components such as Riken resistors and Jensen paper in oil capacitors.
It's not a great topology. Throwing expensive parts at it only makes it expensive rubbish. Putting PIO caps in a muddy design, will make it muddier.
 
Hi Brett,

Re. your take on the Marantz 7C's
cliched 'tubey' radiogram sound

- a classic sound was actually part of the attraction.

Truthfully, I am a little concerned that the spousal unit might not notice the difference from our current SS preamp (NAD) ...

Anyway, the other kit I've been considering is Doc Bottlehead's Foreplay. Better choice?

Thanks for your inputs,
Kirk
 
Hi Kirk,

The Marantz M7 is the most favorate among our DIY friends in Vancouver. Almost every one of them built one.

Some even feed the left and right channels with individual for PS filtering circuit in order to achieve better channel separation and clearer sound. They are using tube regulated power supply in separate chassis with oil capacitors. The bypass capacitors in the circuit are Solen PP. The coupling capacitors are either MIT caps or Jensen PIO caps.

Try one and see how you like it. It is really a good choice.

JOhnny