Magnavox amps

[William]

Over the years, Magnavox made a lot of different amplifier models/series. I know about the 9300 series amp because my Symphony has one. I know about the 8100 series amp because my Imperial has one. My Berkshire has a 150 amp so I know about that one. There are many others that Magnavox built that I know nothing about, and, I'm sure there are others like me. Does anyone on this forum know all the different amps? If so, would you please share the different amp model numbers and what they were found in?

Thank you,
Bill

[Firedome]

Bill, I know very little about them, would you be able to post a pic of your different models and a very brief description so those of us not in-the-know can learn about them, if you have time?

[TC Chris]

One interesting thing is that they used the same basic amp chassis for a long time. It was used in various forms for the parallel P-P 6V6 ones, and then when stereo came along it looks like they simply abandoned the parallel-tube design and plugged two P-P sections into the 4 holes for a while. My two mono 1956 models have larger output transformers than the later models. And one, the Provincial Serenade, has that interesting design with two OPTs, one for woofer and one for tweeter, both using the same output tubes so it's not quite "bi-amped." Bi-transformered, maybe. But i=on the same chassis ad with the same tube complement as its less-exotic sibling, the Magnasonic.

Chris Campbell

[William]

I will work on that, Roger, and post when I figure out how I want to do that. Chris explained it pretty good with his observations over the years. Maybe others will add to this discussion.

Bill

[Firedome]

Thanks Bill, to me the stereo (not 3 ch) amps would be of greatest interest, previous posted info is scattered all over the place and it's hard to impossible to know in what thread to find it, it'd be great to see at least some of it in one place.

Interesting that they used the same chassis for many models, I'd always thought their PPP designs and 3 channel to be an odd choice, though Eico, Heathkit, and RCA did PPP sometimes too, and Moto did some 3 channel jobs.

[TC Chris]

Maggie never made 3-channel devices, did they? They did build bi-amp devices and what I called quasi-bi-amp, the ones with separate output transformers for woofers and tweeters on each channel.

Chris Campbell

[electra225]

Magnavox never built a 3-channel stereo, nor did they build a hybrid. Either all tube or all solid state.

Magnavox amps are quite similar from day one to the last tube amp they built. They are all built to a certain "theme". They are all laid out similarly. If you work on one, you can pretty much work on them all. The Magnavox bi-amps have four amplifiers built into one chassis. Two treble amps, two bass amps. I personally believe they would have been better off to have made a killer traditional amp with exotic output tubes, such as PPP 6550's or something like that. The Magnavox 88 series and the 93 series are only 15WPC, but you can get a lot of performance out of that little bit of power, relative to the solid state receivers from the 1970's. There is a single ended model, the 86 series found in entry-level record player consoles, with or without radio tuners. The 88 series was found in upper level stereos with tuner. Then the 93 series in Symphony, Little Imperial and Stereo Theater models. Then the 81 series bi-amp found in the big Imperial, the the twin 82 series bi-amps found in the Concert Grand. The AMP 176 was the forerunner of the 88 and 93 series. There was another stereo amp, a 148 or a 150 (I'm not sure) that was also in existence in the early days of stereo.

[Hydrolastic]

Hello, The AMP 182 is a biamped stereo amp used in the Continental I have two amps for it a AMP 182 AA and a AMP 182 BA I dont know the watts on it. Or the difference between the two. Hydro

[William]

I'm not sure what the 148 amp went into, but, I do know it existed. The 150 amp is what my Magnavox Berkshire has, and, it's a bi-amp. Both the 148 and 150 are mono amps. If memory serves, I believe Moto-TJ talked about a 148 amp but it might have been back in the old forum.

Bill

[TC Chris]

I've got the AMP-149 in my Provincial Serenade, a 1956 mono console. It's a cool amp. It has an input transformer to to the phase splitting for the push-pull parallel 6V6 outputs. They drive two paralleled output transformers, one for the horn tweeter,one fr the two 12" cone woofers. There are two 5Y3 rectifiers.

The '56 Magnasonic has a big P-P parallel 6V6 amp too, AMP-128A, but with a tube phase splitter and only one output transformer. Two 5Y3 rectifiers. This one has some negative feedback. The other one doesn't, at east as far as I can see. This one drives two 12" woofers and two cone tweeters.

Chris Campbell

[Moto_TJ]

I found this list of Magnavox tube amps, and I really only have any experience with the higher-end models.

https://audiokarma.org/forums/index.php ... ry.947589/. One note on the list, they mislabled the amp-182 as the amp-172, and the specs of some of the amps are a little off from what I have read on the brochures.

My favorites are the Amp-150 and the other two variants that are the same setup. These were usually used in upper-end consoles, and a 150 and a 179 were used in the '58 Concert Grand and in '59 they moved the CG to two 82XX amps. I had the 150 & 179 setup in my first iteration of the FrankenGrand, I really like that setup and am planning on building another continental with that setup.

The 1950's Amp-148, which turned into the 82XX amps in the Concert Grand, was used in the TOTL units. I used two of the Amp-148s in the building of my FrankenGrand Continental.

I have a couple of amp-175s, one in a cobbled together console, and they sound really nice and have a lot of power for what they are. They have about 10 watts per channel, have lots of bass, and are a simple design. The amp-185 is the same basic amp, but has a preamp tube onboard and was intended to be used in consoles without tuner/preamps.

[Firedome]

That is great info, thanks! Be even better if each amp description included a photo.

This buried AK thread is an exhaustive treatise on Maggie amps and mods that can be implemented to achieve maximum performance, with very detailed specs and mods explained in great detail. The O-scope traces are very revealing,
excellent:

https://www.audiokarma.org/forums/index ... t-11575146

The main takeaway being that the 9300 series is the top performing Mag tube amp, for reasons well explained, and that all of their amps have great potential for significant improvements, up to replacement of the output xfrmrs at the extreme.

Has anyone attempted to go beyond stock on their amps? Seems to me as collectors it's best to properly restore but not modifiy. If one wants "golden ear audiophile" performance it's best to go to separate components anyhow, myself I'd prefer to keep my consoles as designed by the factory engineers for the most part.

I've always found it curious that Mag used so many PPP 6V6 designs when PP 6L6 would give more power and a simpler chassis, perhaps the cost of pwr and PTs was the deciding factor? McIntosh used 6V6 and variants for most of their classic tube amps, but of course cost was but a minor factor there.

I understand their later use of 6BQ5 opt tubes, I've always preferred it's sound to 6V6 as output tubes, still do.

[TC Chris]

My oldest Maggie amp is a 1936 model AMP-104 from a "Concerto," a table-top phono with an 8" speaker. I've seen it called the first hi-fi phonograph, but surely there are other candidates (it's like identifying the first rock'n'roll recording). All I have is the amplifier and speaker and a turntable board with a newer Gen Ind. motor (missing the platter) that the volume & tone controls are mounted on.

In any event, the AMP-104 has a single-ended 2A3 output.

Chris Campbell

[Hydrolastic]

Hello, If the early stereos used two mono amps why did the 58 CG use two different amps ?
AMP 150 and AMP 148. It would seem to be more cost effective to use the same amp for both channels. Hydro

[Moto_TJ]

Hello, If the early stereos used two mono amps why did the 58 CG use two different amps ?
AMP 150 and AMP 148. It would seem to be more cost effective to use the same amp for both channels. Hydro

The '58 Concert grand used the Amp-150 and the Amp-179. They are the same basic amp, just tuned a little differently with some changed capacitor and resistor values. Magnavox supposedly did this for better stereo effect?

The Amp-148 was only ever used in TOTL mono consoles. My '57 Brittany had one, the '57 Concert grand had one as well, there were a couple others that used it as well.

I've always found it curious that Mag used so many PPP 6V6 designs when PP 6L6 would give more power and a simpler chassis, perhaps the cost of pwr and PTs was the deciding factor? McIntosh used 6V6 and variants for most of their classic tube amps, but of course cost was but a minor factor there.

It almost seems as if there was a tube-count war going on to see who could use the most tubes on an amp. The Amp-148 has 12 tubes, which sounds really cool to say. Sounds better than saying my amp has 4 tubes.

[Firedome]

Ooops I meant to say McIntosh used 6L6 and variants of it in most of their tube amps, not 6V6. I don't think they ever used an EL34 or EL84.

[electra225]

I agree with Roger that I like to keep my Magnavox equipment fairly close to how it was built. IF I want better, or different performance, my best option is to buy 1970's era component equipment and leave the old Magnavox stuff like it was built. That said, if there were discreet components, such as capacitors or resistors that could be changed to enhance performance better to my way of thinking without modifying the basic concept, then fine. My affection for the 93 series has been explained ad nauseum, so I don't need to go into that again.

[Firedome]

I wasn't aware that Maganvox also made quite a bit of component stuff until looking at eBay and seeing it mixed in with listings for consoles &c. Does anyone own or have experience w/ those? Not sure if it was only SS or did they do so earlier.

[electra225]

I know Magnavox sold Collaro changers as stand alone components. The only experience I've had with Magnavox components is that I bought a Magnavox receiver at an auction. It was made in Taiwan, so I'm guessing that Magnavox didn't build it. Perhaps Panasonic, since they built Magnavox tape decks in consoles. It was a so-so performer, so I advertised it on "Tradio" and sold it for a few dollars. I'm guessing the age as being in the late 1970's.

Tradio was short for Trade Radio that was an hour-long program on the little fleapower FM station back in Missouri. "97 one The Lake. KAYQ, Warsaw". I called the station "97 one, the ad". They had 42 minutes of commercials an hour and played the same old tired mid-70's country they had played for 30 years. Still do. But I enjoyed Tradio. People wanted stuff for free, yet charged full retail for what they sold. I found lots of good stuff on Tradio. But if I hear "Baby's Got Her Blue Jeans On" one more time, it will be too many........

[William]

Per Rogers request, here are a few photos of the amps that are in two of the three Maggie's I have. The single photo is of the 9300 series in my Symphony. The other two photos is the 150 series amp that is in my Magnavox Berkshire which is a mono unit. Sorry, no photo, at least not yet, of the 8100 series amp that is in my Imperial. It's a royal pain in the butt to take the back off and deal with the weird way Magnavox did their remote speaker hook up. There are all kinds of wires that hook to terminals that are attached to the back.

Bill