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Old 24th December 2011, 06:27 PM   #1
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Default Magnavox 139AA schematics, info?

When I was a kid, my first amp was what I believe to be a modified Magnavox 139AA amp. The pictures i have seen of the sams photofact sure look very very much the same. it definitely was the same chassis and transformers.

However a stock 139AA has a 5U4, 2x 6V6's and a 12AX7

Mine had a 5U4, 2x 6L6's a 6V6 and a 6SN7. My dad stated he added the 6SN7 so it is possible that he modified the whole thing.

I am looking for schematics and info for the 139AA amp. specifically what unit was this amp originally installed in? I am assuming a jukebox or maybe a console stereo?? maybe an organ or something??
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Old 24th December 2011, 07:04 PM   #2
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Does it look like this?
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File Type: jpg amp_139aa_493446.jpg (20.6 KB, 100 views)
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Old 24th December 2011, 07:12 PM   #3
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Anyhow it's around a 10w mono amp most likely from a record console.
You see similar models on ebay from time to time. If bought individually can be had for cheap.
Here is an AMP138
6v6 Magnavox mono tube amp 12AX7 | eBay

I saw a couple stereo Magnavox's sell for around $140 these past few days.

Although since you are a Yankee, there should be lot's of Mag's to be found locally for a song.
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Old 24th December 2011, 07:14 PM   #4
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Alright Triple Post!

Join "Magnavox Friends", It's a yahoo group that pretty much has all the Magnavox Schematics. It's a great niche site.
That's were I went when having troubles getting some info on certain models.
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Old 24th December 2011, 10:25 PM   #5
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PM with an email address - I'll send a scan of the Sams for the 139.

It's very similar to the 138 - but has a bigger power transformer and a 5U4 (vs. the 125 mA 5Y3) - maybe powered a tuner?
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Old 24th December 2011, 11:26 PM   #6
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yes that photo is the same amp!! I am curious to look at the stock design and see if i can figure out why dad would have modified it? I would assume changing the 6V6's to 6L6's would have been fairly easy. then a 6V6 used as either a driver or a phase splitter with a 6SN7 as the input tube. he added a volume control to it as well.

I have looked at all the magnavox models i can find and the 139 is the only mono version with the larger upright transformer so it just has to be that amp!
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Old 26th December 2011, 11:55 PM   #7
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Been the Magnavox route briefly a while ago... They are good but not that good. A competantly modified Stereo 70 is a better sounding amp.
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Old 27th December 2011, 12:13 AM   #8
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An ST70 is way over priced for what it is, even before you even start to modify it.

What Magnavox did you have?
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Old 27th December 2011, 01:08 AM   #9
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I don't remember the model off hand but they were mono chassis amps using 6V6's. That was about 18 years ago! They were respectable for a commercially made console stereo amp but nothing overwhelming. Of the five Stereo 70's over the years that have been here the Curcio mod was the best sounding. The ARC modded St. 70 was also nice. The Dynaco Iron was excellent stuff but the original circuit behind them was very lacking, they were cheap however back when they were common. I think the Stereo 70 was a litle over a hundred bucks when I was in HIgh School in the late 60's. Today for a mere $320.00 USD you can get a tube amp direct from China that blows most amps I've ever owned (168 and counting) off the charts including my BAT VK-60... The amp uses 829B transmitter tubes for finals and does ~30 WPC into 8 ohms. Build quality is decent but scrap the Chineese tubes right off with some good tubes. The Chineese are doing some amazing and original things with tubes these days and some of the iron they produce is amazing to say the least.

Mark

Last edited by Mark Allen; 27th December 2011 at 01:12 AM.
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Old 27th December 2011, 01:14 AM   #10
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Fair enough.
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