Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Crazyhorse5 on September 27, 2012, 06:02:24 pm
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Hi new to this board. Im eager to learn and my first question is does anyone know what this is and can you tell me about it?
It has 1 12ax7 tube,2 6v6gt tubes, 1 RCA jack,1 Guitar type jack, 1 pot
The tubes all glow but I m not sure what its used for. On the side it say Chassis assy V-2149
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I am very likely wrong, but I wouldn't be surprised if the 6V6 nearest that silver cap can is supposed to be a rectifier tube instead. Your amp may have come out of a record player or PA .... I not experienced enough to know, but plenty others on here are! Welcome aboard.
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I am very likely wrong, but I wouldn't be surprised if the 6V6 nearest that silver cap can is supposed to be a rectifier tube instead. Your amp may have come out of a record player or PA ....
Yep.
I woudn't fire that amp up again, untill you know for sure.
Can you post a pic of the inside of the chassis? Mainly of the 2, 8 pin sockets.
How many wires are soldered to the 2, 8 pin sockets? If 1 of the 2 has only 5 wires on it and 4 come from the PT it's for a rectifier tube.
Brad :icon_biggrin:
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I just took a look at the pics again and you can see in the 2'nd pic that the tube by the PT and filter cap can is a rectifier tube.
There's 2 (thin) plate structures in it, which would make it a dual diode (full wave) rectifier tube.
I'd bet someone added the 1/4" jack and the pot for volume a control. It's basically a champ amp now.
Brad :icon_biggrin:
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maybe magnovox? cool 6V6 tho - GE black plate 6V6GTA. the other tube is def. a recto - likely a 5Y3GT.
--DL.
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It's surely a 4-watt record-player that someone has put a 1/4" jack onto.
The original brand-name hardly matters now.
There's only so many ways you can do 12AX7 and 6V6. Start tracing the circuit: it will be a LOT like 12AX7 Fender Champ. Main diff is that record-players tend to have Volume control first, guitar-amps tend to put that pot between first and second stage.
Record-players were often very nice musical amps.
We can't be sure of the designed speaker impedance, but 4 ohms is the best bet. Be sure to have *some* load on it, but no harm results from 2 to 16 ohms, just changes in overload flavor and power.
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> found this link
That TV set data has layout and schematic for a _V-2149-3_ audio amp, which is two 6V6, a 5Y3, and a 6C4. No voltage-gain stage. The -3 amp chassis looks longer and lacks the third iron in Crazyhorse5's pix, which is probably filter-choke for the SE version (two 6V6 in push-pull do not need so much clean power).
You may be right that it is from an old monster(*) TV set, but I can't find that audio-amp chassis.
(*) Monster indeed. _Two_ 5U4 rectifiers on the main supply (plus the 5Y3 in the audio), _two_ 6BQ6 H-sweep tubes, all to jiggle a mere twelve inches of CRT.
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> found this link
That TV set data has layout and schematic for a _V-2149-3_ audio amp, which is two 6V6, a 5Y3, and a 6C4. No voltage-gain stage. The -3 amp chassis looks longer and lacks the third iron in Crazyhorse5's pix, which is probably filter-choke for the SE version (two 6V6 in push-pull do not need so much clean power).
You may be right that it is from an old monster(*) TV set, but I can't find that audio-amp chassis.
(*) Monster indeed. _Two_ 5U4 rectifiers on the main supply (plus the 5Y3 in the audio), _two_ 6BQ6 H-sweep tubes, all to jiggle a mere twelve inches of CRT.
Im an idiot its 1 6v6gt and 1 5y3gt sorry
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I m an idiot its 1 12ax7,1 6v6gt and 1 5y3gt. What can I do with this? Can I make a small guitar amp with it. What do I plug into RCA jack and the 1/4" jack?
More Pics
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> Can I make a small guitar amp with it.
...it will be a LOT like 12AX7 Fender Champ. (http://www.el34world.com/Forum/index.php?topic=14439.msg136830#msg136830)
However it looks like someone already guitarified it. Hook a speaker to the OT and ignore the RCA.
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Sorry for my ignorance what does "ot" mean? How do I figure out what impedence the speaker should be? Would this be about 5 watts? I did not see a fuse either wbich bothers me. Cord is newer.
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If you're just getting started in the amp hobby, first thing to do is build a lamp limiter. Dirt cheap, must have to protect against wiring mistakes, and lets you test out new Ebay finds to see if everything is okay on first start up.
OT means output transformer. Any speaker you have will probably do; anything between a 2 ohm and 16 ohm, as PRR said above. 1 6V6 makes 4-6 watts depending on several things. One of the first things I learned here was that 5 watts, 15 watts and 25 watts aren't *really* that different in volume, the difference comes how early you get distortion (to greatly simplify). For instance, my buddy laughed at my little 5watt reclaimed project at practice.... then after a few songs asked me to turn it down. :icon_biggrin:
If you start messing with this stuff, be careful. The amp bug's bite doesn't hurt, but it does cause odd behavior and sends out a pheromone that attracts old test equipment other amp carcasses.