Wiseoldtech, those Magnavox model numbers seem almost cryptic. Especially around the mono/stereo/tube/transistor transition years.
I have a 4MR357P, run# 2 with a similar layout. But installed components don't quite seem to fit the 357 plan from the sales catalog. Larger 9300 amp, but 12" and no horns.
Is there actually a meaning to the full model # in these years?
John, I'm watching with interest to see how you resolve your issue, and applaud you for keeping this one together, looking good and enjoying it! Is there a coaxially mounted tweeter in front of your woofer? I'd be interested in knowing what changes you've made overall.
Thanks so much - I’m excited to see how it turns out too! It’s a wonderful thing and we love having it.
One quick question; on the original mids, which terminals are which? They are not marked on mine so though I should be sure they are wired correctly.
One quick question; on the original mids, which terminals are which? They are not marked on mine so though I should be sure they are wired correctly.
I had one mid wired one way and the other the opposite for some reason - it’s been that way all along and I hadn’t noticed. They rotated the two drivers 90 degrees from each other but then wired them the same way (I.e., positive on bottom). I just presumed that the positive is to the left of the number and changed one accordingly.
I also have two 4 ohms small full range drivers from an old set of Harmon Kardon desktop speakers and put them in tonight in place of the Vifas and BIG difference in terms of top end presence. They don’t sound all that great as they’re just cheap drivers and full range to boot (so the upper mids are too much) but this gives me a sense of how important impedance matching seems to be with this setup. I’m going to also order the cap to do the highs boost tomorrow.
I also have two 4 ohms small full range drivers from an old set of Harmon Kardon desktop speakers and put them in tonight in place of the Vifas and BIG difference in terms of top end presence. They don’t sound all that great as they’re just cheap drivers and full range to boot (so the upper mids are too much) but this gives me a sense of how important impedance matching seems to be with this setup. I’m going to also order the cap to do the highs boost tomorrow.
Magnavox, as did other manufacturers, made design changes during any given product run.
Your "run#2" could be the result of such things.
Also, and it was always quite annoying to me, was that the master Magnavox service bible that I have always went by chassis number, rarely by model #.
One exception in the book is the Top line "Concert Grand" model - 1ST800/801, a monster console with massive electronics and remote control.
The thing weighs as much as an elephant!
Your 93 series amp is a good one (1962/63 era)- however you best get it re-capped, overhauled, resistors checked, etc. (I see dust on it)
They didn't fuse the power trans, so it's a ticking time bomb if not restored properly.
The 9304-20 that I have from an old console, I converted to a standalone amp, with better output trans and mods. (ultralinear transformers)
After all was done, I can honestly say it compares to fancy tube amps costing thousands.
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Nice looking amp!
Yeah, those Concert Grands are hefty and hard to find. Google-sourced pic below of the business side for those who can't visualize why.
I assume that in '62 they were trying to get all of their tube components off the shelves however they could to make way for the transistor models, so odd combinations may be unusual during that period. Mine hasn't been touched beyond taking off the back and getting pic's and chassis#'s. It's just going to be furniture until the vulnerable caps and drifting resistors have been replaced.
So I'm living vicariously through John's work at the moment. Speaking of which- John, you said yours has been recapped, did you go through the preamp/tuner, too? Any changes to the amp?
Yeah, those Concert Grands are hefty and hard to find. Google-sourced pic below of the business side for those who can't visualize why.
I assume that in '62 they were trying to get all of their tube components off the shelves however they could to make way for the transistor models, so odd combinations may be unusual during that period. Mine hasn't been touched beyond taking off the back and getting pic's and chassis#'s. It's just going to be furniture until the vulnerable caps and drifting resistors have been replaced.
So I'm living vicariously through John's work at the moment. Speaking of which- John, you said yours has been recapped, did you go through the preamp/tuner, too? Any changes to the amp?
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I had a customer's Concert Grand in the shop once, along with his 1940 Wurlitzer 1100 jukebox.
Both were massive restoration jobs, but he paid me well, naturally.
None of my restorations were "cheap", but the customer always got first-rate work.
A week after he took the Wurlitzer home, I got a call at the shop - music blaring "Johhny Be Good" - and the guy was raving how beautiful the juke sounded - it was hard to hear him over the music.
Same for the CG, he was floored by its power, so was I.
It rocked the shop windows when I demonstrated it for him.
They don't make 'em like THAT anymore!
Both were massive restoration jobs, but he paid me well, naturally.
None of my restorations were "cheap", but the customer always got first-rate work.
A week after he took the Wurlitzer home, I got a call at the shop - music blaring "Johhny Be Good" - and the guy was raving how beautiful the juke sounded - it was hard to hear him over the music.
Same for the CG, he was floored by its power, so was I.
It rocked the shop windows when I demonstrated it for him.
They don't make 'em like THAT anymore!
Ain't that the truth! The Concert Grand is not a console I'd want to own in Florida. We have enough heat here. 😱
That is beautiful - I've seen other photos of people doing similar things with these amps and I really admire the work and care that goes into not only making this a standalone item but one that looks correct and stylish at the same time.
I didn't do the work mostly because of time constraints between work and family, but gave them both to an old friend who is a tech locally, and older guy that worked on these when they were being phased out back in the day, so he was happy to reconnect with that part of his past for an hour.
I bought all the parts and only had him do the critical caps, I didn't want to do anything that might alter the tone or character of the unit. No changes but am wondering now about the one posted upthread especially if it's something Magnavox did at the time to brighten the units.
As I've mentioned, I have altered the phono section a lot, but mostly everything else is original save the tweeters and the replaced caps.
I have to say, after listening more last night and again this morning this 4 ohm full range speaker has gotten me pretty close to where I want it to be...if it were crossing over a couple thousand hz higher I might consider this done, although I'd imagine the overall sound would have a bit more presence and magic with a better driver. Still...this is close.
Just wanted to follow up; after listening to the full range, cheapo Harman Kardon 4 ohm drivers other than the very top end being a bit rolled off I think I can live with this, or at least may try to find better-performing full range 4 ohms - I'd guess with the treble boost posted earlier by wiseoldtech I might be right where I want to be, and may consider experimenting with the crossover cap value eventually to move the slope up a bit further in the band. But this isn't bad at all, what I have now is pretty enjoyable. I wouldn't have ever considered a full range on the top on a "real" speaker but in this case for whatever reason it's mostly working in a good way.
I now have the EV T35B tweeters, which I don't think I'll use given they are 16 ohms and I really suspect the issues I was having was the impedance mismatch when I didn't have everything 4 ohms. I may relist them on ebay (haven't even opened the box) so if anybody is interested let me know and I'll post when I list them.
Thanks again!
I now have the EV T35B tweeters, which I don't think I'll use given they are 16 ohms and I really suspect the issues I was having was the impedance mismatch when I didn't have everything 4 ohms. I may relist them on ebay (haven't even opened the box) so if anybody is interested let me know and I'll post when I list them.
Thanks again!
I really recommend you give the T35 a try, you will need a 4 ohm LPAD and start with 2.2uF capacitor between the amp and the LPAD.
These are quite good and if after trying them if you don't like them you should be able to sell them easily.
These are quite good and if after trying them if you don't like them you should be able to sell them easily.
I agree with Kevin.
The 16 ohms shouldn't hurt you because they are very efficient.
FWIW, a 16 ohm driver needs 1/2 the cap value for the same crossover point as an 8 ohm driver. If you use a 4 ohm L-Pad, then the 2.2uF cap will give results similar to 4 ohm driver.
The 16 ohms shouldn't hurt you because they are very efficient.
FWIW, a 16 ohm driver needs 1/2 the cap value for the same crossover point as an 8 ohm driver. If you use a 4 ohm L-Pad, then the 2.2uF cap will give results similar to 4 ohm driver.
OK makes sense - I'll give them a try. The 2.2uF is what I have in there now so I'll get the LPADs and see what happens.
And hello to my old stomping ground in MA - I lived in Newton for several years.
And hello to my old stomping ground in MA - I lived in Newton for several years.
I work in Needham literally right on the town line with Newton. Live down on the south shore, just a mile and half south of the Boston city line.
You can order a handfull of bipolar caps from Parts Express to try different values. Once you find what works, go ahead and get a film cap if you want.
Thought I’d follow up; the T35Bs never wound up in the console, but one of them is now living in my mono-setup Karlson cabinet, replacing the tweeter on an EV 15TRX. It sounds so good I can’t bring myself to take it out of the cabinet.
As far as the Magnavox goes, I wound up back with the Vifas in at least for now, but with creative rewiring of all the drivers. Originally they were all parallel, with the amp spec’d at 4 ohms and all the drivers the same. I now have the original mid and woofer wired series with the 8 ohm vifa tweeter wired parallel, and that pretty much solved the frequency response imbalance on the top end in a big way. I’m lacking the bass I had with the original setup, though, so debating what to do about that.
As far as the Magnavox goes, I wound up back with the Vifas in at least for now, but with creative rewiring of all the drivers. Originally they were all parallel, with the amp spec’d at 4 ohms and all the drivers the same. I now have the original mid and woofer wired series with the 8 ohm vifa tweeter wired parallel, and that pretty much solved the frequency response imbalance on the top end in a big way. I’m lacking the bass I had with the original setup, though, so debating what to do about that.