Restoration of a Magnavox Concert Grand model 1ST800F

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Do you want to share my restoration of a Concert Grand?

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Re: Restoration of a Magnavox Concert Grand model 1ST800F

Post by Wildcat445 on Sun Mar 22, 2015 8:35 pm

Thanks, 75. I'm working on preliminary things so my ducks are in a row. I am thinking about using a set of Chatham 5R4GY "potato masher" rectifier tubes.

WC

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Re: Restoration of a Magnavox Concert Grand model 1ST800F

Post by jerryhawthorne on Sun Mar 22, 2015 8:46 pm

Oh my WC, we have nail head motors and stove bolt motors.  I understand the first, not the second.  OK, potato mashers now.  Never worked on a radio with 5R4 tubes.  Do they mash potatoes?  Any advantages over 5U4s?  Used those a lot but never to mash potatoes.  You need to "dumb down" for me! Smile
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Re: Restoration of a Magnavox Concert Grand model 1ST800F

Post by Wildcat445 on Sun Mar 22, 2015 9:02 pm

I'm sorry, Jerry.  I will try to minimize "nomenclature" so as to eliminate confusion.  Very Happy

Chatham 5R4 WG, sometimes with "A", "B", or "Y" suffixes "ruggedized" rectifiers are military grade rectifiers with an unusual body that looks like a potato masher after a fashion.  I want to use them in the Concert Grand amplifiers to stabilize B+ thereby enhancing bass response.

http://www.ebay.com/itm/Lot-of-2-Chatham-JAN-CAHG-5R4WGA-Electron-Vacuum-Tube-Tested-Good-Military-Pair-/111551225961?pt=LH_DefaultDomain_0&hash=item19f8f8a069

I hope this clears up whatever questions you have.  Thanks for your interest.

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Re: Restoration of a Magnavox Concert Grand model 1ST800F

Post by 75X11 on Sun Mar 22, 2015 10:17 pm

Something else learned. I had never seen that type base, they must've been for the Navy.
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Re: Restoration of a Magnavox Concert Grand model 1ST800F

Post by Wildcat445 on Sun Mar 22, 2015 10:55 pm

There was a member on ARF one time whose name shall remain confidential. When I redid my Symphony he recommended my replacing the 5U4 rectifier with a "potato masher" 5R4 if there was room. That tube would interfere with the power transformer in that set, and the same in the Imperial. There is room for 5R4 G's in the Concert Grand, but I believe them to be too tall and would interfere with the back cover of the cabinet. The Chatham 5R4WG series is short enough to clear the back and skinny enough to clear the power transformers. I don't have my RCA tube manual handy, but a 5R4 is generally considered a sub for the 5U4 with increased current handling capability. I Googled a Chatham 5R4 and this is the best I came up with:

http://www.antiqueradios.com/forums/viewtopic.php?f=19&t=252698

Maybe this will explain this better than I have.

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Re: Restoration of a Magnavox Concert Grand model 1ST800F

Post by Bill Cahill on Sun Mar 22, 2015 11:01 pm

It is not a good sub..........

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Re: Restoration of a Magnavox Concert Grand model 1ST800F

Post by Wildcat445 on Sun Mar 22, 2015 11:01 pm

Why not, Bill?

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Re: Restoration of a Magnavox Concert Grand model 1ST800F

Post by Wildcat445 on Sun Mar 22, 2015 11:08 pm

Let's compare specs.  I am here to learn.

http://www.r-type.org/pdfs/5r4gy.pdf

http://www.r-type.org/pdfs/5u4gb.pdf

The sub may not be a good idea.  I see two problems from the get-go.  One is the filter cap specs.  And the 5U4 puts out more DC current.

Bill was right again.   Very Happy

I found this interesting, although it may not add much clarity to the question.

http://www.head-fi.org/t/694525/dubstep-girls-massive-5ar4-5r4-5u4g-rectifier-review-comparison-rectifer-tube-rolling-thread

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Re: Restoration of a Magnavox Concert Grand model 1ST800F

Post by Bill Cahill on Mon Mar 23, 2015 12:35 pm

Most of those tubes couldn't handle it. I'm also noticing the comment on the sound of the tube. They are pusrists that think things like gold plating gives a smooth sound.
And, freezing tubes makes them sound better. Hog wash!!

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Re: Restoration of a Magnavox Concert Grand model 1ST800F

Post by Wildcat445 on Wed Apr 08, 2015 6:45 pm

I just bought a Multiplex adapter for my Concert Grand. Now it will have six chassis and 44 tubes. I'm excited.

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Re: Restoration of a Magnavox Concert Grand model 1ST800F

Post by Wildcat445 on Fri Apr 24, 2015 2:21 am

I have received some information this evening that may shed some light on certain facts that I may have stated in error. In the interest of making this accounting as accurate as I can, I will share this with you.

I have referred to the cabinet style on my Concert Grand as "French Provincial." This nomenclature may not be totally accurate. The nomenclature that best describes the cabinet is simply "Provincial." That is for the 1959 models, as far as I have been able to determine. I won't hazard a guess on the 1960 models at this point. This cabinet for the 1961 models is referred to as "Traditional." To confuse matters further, for the 1959 models, model 1ST800F in cherry finish is "Provincial." In walnut, "Traditional." The model 1ST801F in walnut (and cherry?) is "Danish Modern." I have no idea where I got the term "French Provincial." This may be some of the nomenclature that has become common such as "maggie" and "bi-amps" that apparently has no basis in fact.

I hope this will serve to correct any mis-statement on my part.

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Re: Restoration of a Magnavox Concert Grand model 1ST800F

Post by Bill Cahill on Fri Apr 24, 2015 12:59 pm

If it's any confort to you Magnavox cabinet styles were always confusing from day one. I knew there was no such thing as bi amp, but, who am I to argue with the "experts"?? The 1947 3 way combination cabinet is the same style my father's 1946 2 way combination was. Only three differences.
. My father's set had one fake door, and, one real door for the radio.
This one has two real doors in front, one being for the 12" tv.
This one has the record changer above the radio, since it has a tv.
My father's changer was under a lid on the other side.
My father's had no record storage, but, this one has it under the tv.
Electronically, they were nquite different.
My Fathers had the Amp 101A with the 4 6L6 tubes in PP parallel.
This one has 4 6V6 tubes in PP parallel. Also, my father's amp used 2 5U4 rectifiers, while this one uses 2 5Y3 rectifiers.
The radio on my father's set I believe was a CR 196, and, this one is higher. Very similar. They both use a 6J6 FM oscillator tube. My father's had the old fm band, and, this one has the new fm band.
My Father's had an eye tube, this one does not.
They both had the solenoid push button on the front of the radio to reject the changer on both. This one uses a two speed changer. My father's was 78 rpm only.
My father's had 2 12" woofers, and, a horn tweeter in the middle.
This one uses a 15" woofer, and, 2 4" speakers. One for mid range, the other for high frequencies.
They both had expanded bass, and, loudness. This one also has an ARII scratch filter...
See what I mean??

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Re: Restoration of a Magnavox Concert Grand model 1ST800F

Post by Wildcat445 on Fri Apr 24, 2015 1:38 pm

Thank you, Bill, for that tidbit of comfort. I just KNOW I have seen the reference to "French Provincial" someplace, but apparently not in reference to a 1959 Concert Grand. I have never investigated anything more confusing than Magnavox as far as the various models and nomenclature is concerned.

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Re: Restoration of a Magnavox Concert Grand model 1ST800F

Post by Bill Cahill on Fri Apr 24, 2015 3:49 pm

I knew you'd appreciate mass confusion.............. Very Happy

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Re: Restoration of a Magnavox Concert Grand model 1ST800F

Post by Bill Cahill on Fri Apr 24, 2015 3:51 pm

Hmm. Just as much mass confusion as with the Edison company. So many kits, combinations, horns, and, models of machines it just boggles the mind......

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Re: Restoration of a Magnavox Concert Grand model 1ST800F

Post by jerryhawthorne on Fri Apr 24, 2015 5:50 pm

Mostly we just add a lot of confusion but it is fun. Go for the Maggie (just to bug you with the name). There is always something to learn from your knowledge.
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Re: Restoration of a Magnavox Concert Grand model 1ST800F

Post by Ragwire on Mon Apr 27, 2015 1:09 pm

I can't find the voting "button" but I am interested.
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Re: Restoration of a Magnavox Concert Grand model 1ST800F

Post by Bill Cahill on Mon Apr 27, 2015 6:46 pm

Yah. Where is the voting button??

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Re: Restoration of a Magnavox Concert Grand model 1ST800F

Post by Wildcat445 on Mon Apr 27, 2015 7:46 pm

If I remember correctly, the "voting button" only worked for a few days.  It has expired by now, probably.  I appreciate you guys' interest.  I have you down for a "go for it."  Life has gotten in the way temporarily.  I have parts ordered, a five gallon bucket of caps and resistors, and am awaiting the MPX adapter than I had, didn't have then had again.  After I get the parts together and I get caught up on mowing and get my bench and shop cleaned off enough to work, I'm on it.  The frau has removed her "girl junk" off the cabinet of the Concert Grand, and I have it with its butt facing the center of the room.  If I take the back off, and leave it off, I will have a cat trying to help me. Rolling Eyes

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Re: Restoration of a Magnavox Concert Grand model 1ST800F

Post by Wildcat445 on Wed May 13, 2015 2:01 am

I am on the cusps of a dilemna with this project. I will need a large quantity of caps and resistors for this instrument. The caps pose no particular problem. Resistors are another matter. I either have the choice of paying too much for a package of five, or I have to order an assortment with sizes I have to store, but will likely never use. Neither option particularly appeals to me. In the interest of allowing me to adhere to my typical cheapskate tendencies, I have decided to "cheat" so that I can order the parts I need without having to buy and store those that I don't.

I have decided to take the amp chassis out of the cabinet and measure all the resistors and other components I will need and make a list. All the caps will have to be changed, so those are a given. I am going to make a copy of the Sams manual for the amp chassis and make notes of the values of each resistor in the amp. Then I can order what I need and can keep the project moving without interuption waiting for an overlooked part. This project is becoming more time consuming and more expensive than I realized. There are a LOT of parts in this thing. I am going to use radial electrolytic caps since not only are they less expensive, they work better mounted on terminal strips or when restuffing a can. I entertained the idea of using "better" capacitors for this project, but have decided that caps from my usual sources should work just fine. I don't see the need of paying over a dollar each for "audio grade" capacitors. I'll have more in electrical components than I gave for the instrument. I have a budget for this project, and need to stick to it. I have the Multiplex adapter in, FINALLY, and I have it cleaned up and ready to go. About all there is to do to it is to test tubes and there is an electrolytic cap that I am going to leave alone. Further testing of the MPX unit will have to wait until I get everything else up and running. That will give this instrument a total of six chassis and 44 tubes. I have counted over 20 electrolytic caps so far, and I'm not done. I plan on having to change nearly every resistor in both amplifier chassis. I am going with 1% metal resistors in lieu of the 20% carbon resistors in applications other than power resistors.

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Re: Restoration of a Magnavox Concert Grand model 1ST800F

Post by Bill Cahill on Wed May 13, 2015 8:47 am

You people act as if all carbon resistors are junk, which simply isn't the case....

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Re: Restoration of a Magnavox Concert Grand model 1ST800F

Post by Wildcat445 on Wed May 13, 2015 10:04 am

In this application, I like to use resistors that are more accurate than 20%. I have at least a theoretical condition that I am attempting to remedy. These amplifiers have six 6V6 output tubes connected in parallel. It is important that the components in this circuit not only be accurate in value, but as closely matched as possible. Carbon resistors have their place, but Magnavox amplifiers are not one of them.

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Re: Restoration of a Magnavox Concert Grand model 1ST800F

Post by Bill Cahill on Wed May 13, 2015 10:15 am

You make it out that they are more critical than they really are. There are certainly circuits that are critical, but, not all...

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Re: Restoration of a Magnavox Concert Grand model 1ST800F

Post by 75X11 on Wed May 13, 2015 2:49 pm

It's a mighty special unit to him. I'm sure he wants the best he can provide for it, as he wants the best he can get from it.
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Re: Restoration of a Magnavox Concert Grand model 1ST800F

Post by jerryhawthorne on Wed May 13, 2015 4:08 pm

If it makes WC happy, I'm happy. The cost difference is quite small. Smile Smile
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Re: Restoration of a Magnavox Concert Grand model 1ST800F

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