First tube amp!!! :D

General discussion area for tube amps.

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GuitarSlingerX
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Joined: Mon Feb 25, 2013 9:40 am

First tube amp!!! :D

Post by GuitarSlingerX »

Hey guys :D I scored a little old Magnatone tube amp and lap slide guitar from my grandma today! Ive been playing guitar for about 10 years. within the last few months ive been doing a bit of reading up on tube amps. Ive allways had solid state amps and these beautifull little tube amps are quite different and from what I read deadly if your not carefull when u work on em. Im really excited about getting this old tube amp. It belonged to my grandpa who I actually only have seen in pictures, videos and old records :) Id love to play on his old guitars through his little old magnatone amp but its in kinda rough shape. Ill put up some pics of it to let u guys see what I got myself into x)

What im mainly concerned about is turning this baby on and frying things cause a component isnt up to par from old age. I actually dont know what power tubes were in it. Is there something in the circuit i can check like capacitor values or something that would give away what power tubes were being used. Any tips on how a should go about getting her ready to fire up would be greatly appreciated :) Im gonna check out the site more and see if I cant get an idea of what I should be checking.
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martin manning
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Re: First tube amp!!! :D

Post by martin manning »

Can you determine the amp's model number? There are Magnatone schematics and other resources on the web that can help you find out what the correct tube types are. If you measure the output transformer voltage ratio and calculate the load impedance, a guess could be made, but it would be better if you can locate a schematic.

Post a few pictures of the inside of the chassis and the outside of the amp.
GuitarSlingerX
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Re: First tube amp!!! :D

Post by GuitarSlingerX »

Heres those pics :) The only number i could find was a serial number I think.
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GuitarSlingerX
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Re: First tube amp!!! :D

Post by GuitarSlingerX »

more pics...it posted them the opposite of how i downloaded em so their not in the order i wanted em but itll do :P
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Cygnus X1
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Re: First tube amp!!! :D

Post by Cygnus X1 »

Cool.
Definitely due for some cap replacements and safety updates.
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martin manning
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Re: First tube amp!!! :D

Post by martin manning »

Is that stamped tag the only place "Magnatone" appears? Can you post a picture of the top side of the chassis? There is a Magnatone-Valco Yahoo group that might help with identifying this thing.

Have a close look at the pots and transformers and see if you can see a six-digt number. That will be the EIA code withe the first three digits being the manufacturer and the last three being year-week-week.
mr_hankey
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Re: First tube amp!!! :D

Post by mr_hankey »

If you want to learn more about amps, how they work, what makes them different from each other, I can't recommend "The guitar amp handbook" by Dave Hunter enough!
GuitarSlingerX
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Re: First tube amp!!! :D

Post by GuitarSlingerX »

Dang thanks for all the suggestions and help guys :) Yeah I surfed the magnatone sites for a bit but i wasnt really finding alot of them like my little amp. I ended up going on ebay and google image search and still only found very few that resembled it. one exact same one but there was no info. Ill keep looking around though. I did see those numbers on the pot 500k 304932 so is it a 32nd week of 1949 amp? I think a transformers missing possibly. Isnt there suppose to be 2? Theres what i think is a little transformer wired to speaker and tube sockets. The number on it is
B-137723A
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M Fowler
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Re: First tube amp!!! :D

Post by M Fowler »

It looks like an older version of the 1952 Magnatone Varsity I just repaired for a local guy. A lot like a Fender 5C1.
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Structo
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Re: First tube amp!!! :D

Post by Structo »

I may be a power transformerless amp.

Which means it is powered directly from the wall voltage.

No power transformer to isolate the chassis from high voltage.

Very dangerous to operate.

If this is the case, it is recommended that you get a 1:1 isolation transformer and have it installed.
Tom

Don't let that smoke out!
GuitarSlingerX
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Re: First tube amp!!! :D

Post by GuitarSlingerX »

Hey guys I found a pretty good article on the isolation transformer upgrade to these death trap amps. It actually covers alot of stuff on basic safety upgrades and information. Just figured Id post it up for anybody that might stumble on this thread with pretty limited knowledge on the subject like myself.
http://www.instructables.com/id/Isolati ... itar-amps/
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Phil_S
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Re: First tube amp!!! :D

Post by Phil_S »

Welcome to TAG! IMO, you have a valued antique that could still be a great player amp. As others have already said, it needs attention. If you are not experienced with tube amps, it is not great a first-timer's project, partly because of its age and its place in history, and partly because it presents a few problems that will be better handled by someone who already knows what to do. There is so much of this sort of work that is second nature to people who do it and to others, well, they just haven't developed that 6th sense yet.

Tell us where you are located. Maybe you will get a recommendation of where to take it. There is a good chance you will be rewarded if you are willing to invest in some modest but essential and way overdo maintenance. It is my belief that folks here will only send you to someone who is known to be honest, competent and reliable.

Whatever you do, don't try to plug in that amp. There is significant chance you will regret the day you did it.
GuitarSlingerX
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Re: First tube amp!!! :D

Post by GuitarSlingerX »

Thanks man! Im from Placerville California pretty much between Sacramento and Tahoe. Ive found some pretty promising websites for amp repair places near by but ill have to actually wait a few weeks before I can put any real cash into it. Im just about to put a new trans in my 74 stepside so cash is tight. This amp is priceless to me though so it will get the long overdue tlc it deserves. Id love to leave it as un tampered with as possible but I know its been neglected and needs gone throug...and to be made death proof x.x Any suggestions would be great cause I wanna find an amp tech that will know whats gotta go and whats still just waiting for that electricity to bring it back to life :twisted:

I actually just watched a video of an amp tech that had a customer bring him an old fender tube amp to check out. The customer had it repaired elsewhere and had the other place save all the original componants they removed. The amp tech tested all of the original componants that were removed from the amp and found many were fine to stay in that amp and the customer was just getting ripped off :( I really would hate someone like that to get their hands on my grandpas old amp :x
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M Fowler
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Re: First tube amp!!! :D

Post by M Fowler »

The funny thing is I own one of those Mark 1 amps :lol:
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M Fowler
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Re: First tube amp!!! :D

Post by M Fowler »

I actually just watched a video of an amp tech that had a customer bring him an old fender tube amp to check out. The customer had it repaired elsewhere and had the other place save all the original componants they removed. The amp tech tested all of the original componants that were removed from the amp and found many were fine to stay in that amp and the customer was just getting ripped off I really would hate someone like that to get their hands on my grandpas old amp
Well I disagree with many techs in that regard as to keep old wax caps and other questionable caps. A lot of guys want the amp working to use not dust off every 4 years. If it was some rare breed maybe or holy grail Marshall with mustard caps but an old 5C1 or this Magnatone fix it to be played through.

The Magnatone I fixed needed new OT, new speaker, new handle, and replaced many of the old caps. Cleaned the pot and wired in a 3 prong cord. I placed all the old stuff in a bag and handed it to the owner. He loves the amp.

Mark
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