Magnavox 9304

Blackburn

New Member
I've an all original 9304 chassis with original tubes on its way to me and I'm curious if any folks here have some info on the OTs that came stock with these. I figure on installing some 8K Edcors for what I think will be superior freq response and the multi sec winding.

What is the overall consensus of these models? I've read good things.
 
I think this will tell you all there is to tell about the stock circuit, how to improve it with the stock transformers, and one possible upgrade transformer path.

http://audiokarma.org/forums/index.php?threads/more-fun-with-magnavox-the-9300-series.687735/

My own variation, using a lot from that thread but paired with a set of Edcor transformers can be found here:

http://audiokarma.org/forums/index.php?threads/magnavox-9300-with-edcor-cxpp25-ms-8k-iron.754809/

you want post #20 for the final schematic revision.
 
I was going to replace the stock 4 ohm output trany's on mine, but the stock ones sound pretty nice, so I left them alone. I do have a nice pair of 8 ohm Edcores for a 175 I'll be building though.
 
Thanks for the info. Nice to note that mine is exactly like the model tested in that thread. I've not yet ordered the OTs and at this point I don't know that I will. Lots of nice things said about the originals. I'll just have to judge for myself. Did you prefer the result using the Edcors over stock?
 
The 9300 are all basically the same, other than small changes in feedback circuitry.

Honestly its been so many years since I've heard a stock one that I can't even say for sure. At one point I had a stock one and the modified one and I liked the modified one more. The Edcor version has undergone a considerable amount of further tweaking and improvement since then but I've never had a chance to put it up against a similarly tweaked 9300 with stock transformers to really hear it side by side.

If I had to do it all again, I'd probably do everything with the stock setup, then consider upgrading the transformers if that still fell short. The circuitry will work with both so its not a wasted effort.
 
The stock OTs sound surprisingly good. A bit rolled off at the extremes. I'd say give it a listen before replacing them.

But I have done all of dgillespie's mods on mine except OPT replacement, so my results may differ from yours.
 
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http://www.edcorusa.com/cxpp25-8k23 Is the output you want when you upgrade .

I have installed several of the Edcors on magnavox amps , and there is a big difference between the OK stock transfomer and the Edcor



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The amp in the bottom photo is on my desk for my computer system along with a Grant Tube DAC -11 and KEF Corelli speakers , there is a big difference in the low end on and top end .
The outputs on this amp came out of a pioneer receiver and are almost as good as the Edcor's , i have heard the stock transfomers up against the Edcor's and other transfomers output transfomers
And the stock one's lack bass below 100 Hz and symbols sound like sand is being poured on them instead of using brushes , most of it is due to poor transient response .

It takes 6 + weeks to get the Edcor's order them now , and listen to the stock ones until they arrive .
 
Thanks for all the info. I got mine in on Friday and tried it out. One of the quad was redplating intensely. Funny as it is, that one showed pretty severe signs of over work and I managed to put it in the very socket it must have been in before lol. I replaced both Good Alls with a couple NOS EMs and popped in my set of EL84Ms and we're good. I bought a little U-Turn RIAA preamp a while back and was dismayed by the output with one of my turntables. I need to build up my phono/driver pre and see what this thing is like, though there is that unused socket on the chassis that's begging for a driver. Any tips? I was thinking about a 12AT7 but being new to hifi I'm curious about the placement of the volume control. I was thinking cap isolated at the front. Ideally I'd want to follow the tube with that control, but I don't want to bother the impedance of the PI entrance. I've seen and read a bit about adding a 100K control on these Mag chassis, but isn't that a bit low? I heard one in use on YouTube and it seemed alright. What's the general take on that?
 
Here's one option:

More Fun With Magnavox: The 9300 Series

feel free to sub a 12ax7 for the 6eu7. Functionally they are identical, though the chassis is stamped for a 6EU7. Thats the real reason I used one on mine, that and it makes sure I never rob the tubes from the Magnavox. I own absolutely nothing else that uses that tube, so its the one amp that I never rob from when I get something in that is missing the 12ax7's.
 
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