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magnavox 101b amp

Jcricket

Jcricket

not someday, but today
Subscriber
I did a forum search and got no results, I did a goodle search and found some trheads on AK> go figure?

Anyway, has anyone ever done a rebuild/conversion on the Maggie 101b Amp. It uses a 6v6 PPP section and has some pretty hefty iron. It also uses a 250 ohm filed coil speaker - at least that is my understanding. I think I found a set of schematics on fleabay.

Anyone have ideas or opinions on this amp?


Mark
 
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It almost sounds like it might be better to redesign the circuit - I have never done that, but I guess there is always a first.

Probably add a couple of 12ax7's or other appropriate tubes. Maybe see if I can find anotehr matching OPT and convert it to a stereo 6v6. I wonder.....

Time to get the schematics and do some studying!

Thanks Tom.

BTW - I found five 1 meg dual gang, dual control pots witha loudness tap on the auction site. They ae linear though, so I am not sure what is going to happen if I install one on my unit.

But for $20 shipped for the four - I am going to find out.

Mark
 
Could be tone controls with center contact for "bypass" - can't imagine a linear pot with loudness tap...
 
I was thinking like you, I bet these have an audio taper, they just didn't know it.
 
Jcricket said:
It almost sounds like it might be better to redesign the circuit - I have never done that, but I guess there is always a first.

Probably add a couple of 12ax7's or other appropriate tubes. Maybe see if I can find anotehr matching OPT and convert it to a stereo 6v6. I wonder.....

Time to get the schematics and do some studying!
Click to expand...

You could make it a stand alone amp by copying the AMP142 circuit. This would entail adding a 12AX7, removing the input transformer and replacing the field coil with a choke.

You could also make it a stand alone stereo amp but then you'd have to remove the input transformer, add 2 12ax7 (or 12at7), replace the single output transformer with 2 new ones and add a choke. It would be cheaper to buy (or reclaim) a stereo magnavox amp like the green AMP182 I now have.

These amps don't sell for much so if you're going to modify it you should have a purpose in mind before you start cutting holes. It might be easier to pair it up with another 101b and have a decent transformer coupled dual mono setup for less than the cost of a single output transformer. If you need to boost the level to the input transformer you could use something like this: http://www.angelfire.com/electronic/funwithtubes/Amp-Gain_Block.html
 
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Hey All,

I scrounged a Magnavox 101b from a console a friend gave me. And yesterday I found a 101a for 22.50 on eBay. I was thinking of building a small pair of mono blocks. Does anyone Know what the taps on the power transformer voltages are?
 
I keep telling myself I'm going to use 2 101b's, and the factory 12 inch dual field coil drivers for a open baffle experiment . . .
 
mr2racer said:
I scrounged a Magnavox 101b from a console a friend gave me. And yesterday I found a 101a for 22.50 on eBay. I was thinking of building a small pair of mono blocks. Does anyone Know what the taps on the power transformer voltages are?
Click to expand...

I've got the measurements somewhere. I recall the voltages were rather high. After removing the speaker fields coils from the circuit, I decided I would need to go choke input on the power supply to get the B+ down to a reasonable level for 6V6.

I hijacked a thread around here somewhere, and I think I posted the voltages in it. Search around and maybe it'll turn up. By the way, I never did finish the project so I can't yet say how it turned out.

edit: Here's the thread: http://www.audiokarma.org/forums/showpost.php?p=3062788&postcount=20
 
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