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Topic: Restoration of Albert talley's 1954 Bassman--- Cabinet done! |
Ken Fox
From:
Nashville GA USA
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Posted 26 May 2009 10:48 am |
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Work in progress for what Gregg Hopkins at Vintage Amp restoration says is the oldest 4-10 Bassman he has ever seen!
Built Nov 1954, serial #0035!!
Gregg is doing the cabinet for Albert and I am doing the amp restoration!
Rarest of rare, only a few of this 5D6 circuit were made. Had two 5Y3 rectifiers. Shortly after that the 5D6A circuit was redesigned and used 5u4GB rectifiers
!
Last edited by Ken Fox on 26 Nov 2009 4:47 am; edited 1 time in total |
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Ken Fox
From:
Nashville GA USA
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Posted 26 May 2009 10:50 am
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Ken Fox
From:
Nashville GA USA
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Posted 26 May 2009 10:57 am
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The 1954 power transformer was very tired! So much heat that the bobbin papers were just toasted. I ordered a new transformer. The option of having the original rewound at $350.00 by Mercury Magnetics is not what was decided on. The new one is a Fender made replacement to replace the early Bassman amps transformer.
Also the original did not have a bias tap! They adding a big dropping resistor to the HV tap on the secondary. The only other amp like this I could find on the net belonged to a friend of a friend. I got pictures of his and there were three big resistors (different values, though) in his circuit as well. His serial number was much higher so I suppose they had make a few tweaks by then!
There is no record of a 5D6 schematic or drawing for the amp. Though similar to the 5D6A it does have some minor differences. The 5D6A in fact had a bias tap!
The old caps were either bad or had drifted so far off they could not be used. All Sprague Atom caps, Mallory 150 tones caps and an Orange Drop at the polarity switch. A few resistors were out of spec and were replaced with correct carbon comps. A new grounded power cord for safety as well
I went a step further and removed the old solid state selenium rectifier. I added a bias pot on a stand-off, attaching it to the two holes in the chassis that existed. Now it is an adjustable bias amp.
Tone is outrageous!!!! Can't wait to see the cab back from Greg Hopkins and the finished product. The cab will be restored to it's original glory and will host the 4-10" original Jensen speakers.
Last edited by Ken Fox on 26 May 2009 11:19 am; edited 1 time in total |
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Kyle Everson
From:
Nashville, Tennessee
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Posted 26 May 2009 11:03 am
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| When you say "restore" the original cabinet, what does that entail? |
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Ken Fox
From:
Nashville GA USA
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Posted 26 May 2009 11:14 am
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Gregg Hopkins is the foremost cabinet guy in the US today. He has also co-authored books on Fender amps.
The original tweed was long gone and the amp had Tolex on it.
It will be re-covered with correct tweed, new correct grill cloth and then the cab will be be treated to appear aged. Greg uses the correct Pot Devin glue machine with animal hide glue.
Here is a link to Gregg's site:
http://www.vintage-amp.com/cbrestor.htm |
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Ken Fox
From:
Nashville GA USA
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Posted 26 May 2009 11:16 am
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| I must say that I wanted to share this rare amp's restoration with my fellow Forum members. I am not seeking approval or condemnation for the work done!! |
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James Morehead
From:
Prague, Oklahoma, USA - R.I.P.
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Posted 26 May 2009 11:25 am
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UNBELIEVABLE!!! Way to go Ken. Way to go Albert on such a rare cool score!!  |
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John Billings
From:
Ohio, USA
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Posted 26 May 2009 12:52 pm
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| Looks great Ken! When my tech serviced my '52 Pro, he put the new caps inside of the old ones! Looks original. He's totally anal! |
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Bill A. Moore
From:
Silver City, New Mexico, USA
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Posted 26 May 2009 3:27 pm
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| Ken, what does the selenium rectifier do, that you could remove it? I haven't looked, as I've seen them in these old 50's circuits, I just thought it had something to do with the power supply. Bill. |
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Ken Fox
From:
Nashville GA USA
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Posted 26 May 2009 4:26 pm
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| Bias supply diode. They are considered a health hazard!!! |
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Blake Hawkins
From:
Florida
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Posted 26 May 2009 4:43 pm
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If the selenium rectifier overheats and burns out,
you get a "rotten egg smell." Mostly their resistance increases with age. Installing a silicon rectifier in its place is always a good thing.
Ken, you did a beautiful job on the restoration.
The pictures speak for themselves.
I was very impressed with your control panel. How
you got it polished without losing the silk screened
letters and numbers is a wonder.
The whole thing is a work of art. Thanks for sharing
it.
Blake |
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Steve Norman
From:
Seattle Washington, USA
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Posted 26 May 2009 4:52 pm
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Thats incredible, # 35? man.
where those the original caps in it? If so I cant believe they lasted that long. I hope you can post some sound clips when your done!
_________________
GFI D10, Fender Steel King, Hilton Vpedal,BoBro, National D dobro, Marrs RGS |
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Steve Norman
From:
Seattle Washington, USA
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Posted 26 May 2009 4:53 pm
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Thats incredible, # 35? man.
where those the original caps in it? If so I cant believe they lasted that long. I hope you can post some sound clips when your done!
_________________
GFI D10, Fender Steel King, Hilton Vpedal,BoBro, National D dobro, Marrs RGS |
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Ken Fox
From:
Nashville GA USA
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Posted 26 May 2009 5:16 pm
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I cleaned it with soap and water and used car wax on it.
Most of the caps looked original and the amp did not work! It was out I suspect for a long time.
Albert found the cover and it has the name of the guy he sold it to years ago!
Looks like he found his old amp that he bought in 1955 when he was playing with the Playboys!
I was playing with my Tonka trucks in the sand at that time!!
Maybe we can get Albert to do some clips for us! He will bring the finished amp to the Dallas Show for sure!!! |
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Kyle Everson
From:
Nashville, Tennessee
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Posted 26 May 2009 7:22 pm
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Thanks for clarifying, Ken. When you said it would be restored to its original glory, it made me wonder how much of it had been tampered with over the years. Given the circumstances, it's nice to know that an amp that sounds this good will look just as nice.
Would you mind explaining the solid state selenium rectifier? What's the connection between that and the two 5Y3s? |
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Mike Schwartzman
From:
Maryland, USA
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Posted 26 May 2009 7:37 pm
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Now that's a real cool project, Ken. Thanks for showing it. I recognize those old orange Astron caps...I've seen them in a couple of real old amps, but not quite that old 
_________________
Emmons Push Pull, BMI, Session 400, Home of the Slimcaster Tele. |
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Chris LeDrew
From:
Canada
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Posted 26 May 2009 7:47 pm
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| Wow, Ken....you must feel proud to be working on a rare bird like that. And how lucky they are to have your knowledgeable hands on it! |
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Cliff Kane
From:
the late great golden state
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Posted 26 May 2009 7:55 pm
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Oh my god, you've removed all of that lovely patina! The horror...the horror.
Thanks for posting these fantastic pictures, Ken. It looks like a real gem and great restoration. |
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Danny Bates
From:
Fresno, CA. USA
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Posted 26 May 2009 8:02 pm
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Beautiful Job Ken!
I have an all original '62 (Brownface) Vibrolux that I'd like to have you check out. It sounds great but I think she's gotta (at least) be due for some caps. Email or PM me with shipping info. Thanks |
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Ken Fox
From:
Nashville GA USA
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Posted 27 May 2009 4:43 am
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Kyle, in any Fender amp that usse fixed bias a negative bias voltage is created by a solid state rectifier diode. A voltage on the range of -45 to
-50 VDC is common. In a cathode biased amp it is not used. In the old days the selenium rectifier was all that was available. However selenium is a poison and the fumes are quite deadly. When I see one in an amp I replace it with a common solid state rectifier diode such as a IN4005.
The 5Y3 tube provide the positive voltage to the plates of the power tubes and preamp tubes. Plate voltage on this amp is just a bit over 400 volts DC.
In some Fender amps the choice is a solid state rectifier scheme, such mas the Twin Reverb. |
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J Fletcher
From:
London,Ont,Canada
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Posted 28 May 2009 9:38 am
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Hi Ken
That's quite an amp. Being the Fender amp nerd that I am, can you post the transformer and choke code #'s? I'm always curious about that. By the way, a friends 1960 Biggyback bassman hasn't any bias winding either. Uses a 220k resistor off the HV winding.
Thanks...Jerry |
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Ken Fox
From:
Nashville GA USA
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Posted 28 May 2009 9:57 am
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| The transformers are, PT 7926, OT 2770 and choke 14560. |
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Kevin Hatton
From:
Buffalo, N.Y.
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Posted 28 May 2009 11:55 am
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| Beautiful job Ken. |
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Mitch Druckman
From:
Arizona, USA
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Posted 29 May 2009 12:14 am
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| Beautiful work Ken, although I think your client should have had Mercury rewind the original transformer. |
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Ken Fox
From:
Nashville GA USA
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Posted 29 May 2009 4:07 pm
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He has the original and could have that done. However the new one works just fine and has a bias tap. The amp may not be original but it sure works great and now has an adjustable bias as well.
Mercury wanted 350.00 to do a rewind. I think that is just too darn much! |
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