60's Vintage TNT Bass Amp

[Archie Speed]

something perhaps a bit unusual. This amp came out of storage in a barn. Had about 35 years of dust on it. 2 12AX7's (GE) and 4 ea EL34 (marked RCA GT-Britain 6Ca7/EL34). A very heavy beast of an amp head.

Condition? Main input fuse is blown. At least 2 of the EL34's show signs of flaming. No other obvious signs of component burning. Eyelet board inside is broken in a few spots. Wiring is sloppy & a mix of every wire gauge known to man as well as whatever color was available. Call it '60's wiring'. That wiring which is cloth insulated has deteriorated. Don't know yet about condition of PT, OT or choke.

So...I'm in the process of reverse engineering this amp in an attempt to come to grips with whether or not this is a worthwhile salvage operation project. It appears to be pretty much original issue. Certainly has my interest.

Question: Anyone ever heard of these amps? We're talking 40-50 years on.

Regards,

Archie

[Enzo]

Just thinking, if I had to guess, I'd suggest that the original TNT whatever it was was torn out, and someone built a one channel basic tube amp in there. That would explain all the hole plugs, the cockeyed part board, the mishmash of wires. None of that looks original. Someone stuck a couple orange drops in there. Are those larger caps Vitamin Q?

ANyone making amps with all those unused panel holes, labelled at that, if they wanted to sell a more basic amp like this, they would have made a new panel escutcheon to cover the holes, and labeled only for what was there.

I could be wrong.

[Justin Thomas]

The whole thing looks "cheap Ampeg copycat" from the outside... or Bassman 100/135... Any numbers on the trannies? Pots? As it's likely already been hacked, if the expensive parts are good, go for it! 2 12AX7s & 100W is all you need to kick ass. Those trannies pook plenty beefy to add another 12A_7, too. Have fun!

Justin

Please tell us there's a cap doghouse... zap!

[Archie Speed]

Thanks, Enzo. You probably are correct! I just attributed the quality of construction to the haze of the time in which it was made. Didn't dawn on me that someone did a home build/mod. Again...duh. But I don't get out much anymore.

Yes, those nice silver caps are indeed Sprague Vitamin Q's, labeled as '.1/600VDC'. The yellow paper electrolytics are Aerovox.

Simple enough amp. Think it a worthwhile rebuild? No cost to me so far. New tubes & caps will change that. Making up a new eyelet board & rewiring...just time.

[Archie Speed]

Justin,

Nope, no 'doghouse'. As you see it in the pic. Thrillseekers. If I get that far, I'll make one though.

Numbers...PT has a stencil that as near as I can make out reads 'H-5031'. OT has a stencil '1070'. choke has 'N-5195-1' over '606416'. No joy searching those numbers (yet).
Pots are grimed up & I'll have to remove them to see what's there.

[Enzo]

I think 606 is Schumacher and 416 would be the 16th week of 1974. Looks too late for 1964 and too early for 1984.

[vintagekiki]

Unfortunately amplifier that you have is some diy in the factory head box.
Not helpful, but at least you've got an idea of what kind of amplifier is done

https://www.flickr.com/photos/steven_quick/sets/72157600953163731/

Try to find some information on yelow pages TNT Electronics Los Angeles CA 90025, or try to get in touch with Steven Quick on www.flickr.com

[J M Fahey]

Or forget TNT what it isn't any more and consider it half a kit: iron, chassis, cabinet, sockets.
And I'm not that certain about the last, they might be weak/worn/rusty.

No point in repairing it anyway.

Strip it clean, junk old pots, jacks, etc and build there whatever you like.
Just keep it simple, often the temptation is to build a 3 channel 6 mode active effects loop simulclass whatever.

If interested in Bass, a single channel Bassman or Ampeg (preamp) and a classic Fender Power amp will be killer.

If guitar, Fender AB763 or Marshall Plexi or JCM800 are doable.

Since the original was clearly a black or silverface Basssman clone , the transformer should be able to feed as many filaments (4 or 5 12AX7) as it used.

You should spend relatively little on any of those projects, since you alredy have all the expensive parts.

Personally I'd be happy with such a find, as is.

Keep us up to date

[Archie Speed]

Amazing find. Thanks, vintagekiki. I'll chase those leads down & see what history I can find.

J M Fahey...using the basic skeleton as a foundation for a 'new' build was one direction I was considering. More so now that I've got feedback from you folks. A guitar head would be nice. Then again, this was configured as a bass amp & a Blackface Bassman would be fun to build & even more fun to play through.

Agreed though, keep it simple is key.

Archie

[Archie Speed]

Now this is turning into a 'kid in a candy store' obsession. as to what to build. I'm strongly leaning towards a AA165 Bassman, or variation thereof. A Plexi or JCM800 are running a close second. Even considered a JCM-45. Bassman seems the most versatile.

Sockets are ok. No rust or breakdown. PT leads are a bit scary as cloth insulation has deterioration. Tear down in a day or so & I'll see more of whats there, what works & what might not.

Thanks, folks.

Archie

[52 Bill]

Agree with the others, definitely modded by a diy'er. The phase inverter has been connected directly to the first node of the power supply.

The only time I've ever seen a TnT before was at an outdoor festival type show in the early '70s. The band was a power trio Bass/Drums/Guitar. They set up the amps and before doing anything else they set a 12" table fan blowing directly into the back of each head.

Remember if the original output transformer is reused it was designed to run 4-EL34s.

[vintagekiki]

Hi Archie

If you want to do in existing chassis DIY amplifier, then do some exotic things.
Make replicas amplifiers '60 and '70 years, it's like a heated hot water. Everything is already known, simply do not have any motive, and you have no challenge.

For DIY amplifier you have more than 70% of the necessary essential items. The head, chassis, transformers. It takes only get a handful of resistors and capacitors, and arm yourself with patience.

Do not forget, quality amplifier makes 40% of materials and 60% of the effort.

If you'd asked me, I'd choose the amplifier that is quite rare, and as far as I know nobody had not tried to do.
It is about the legendary Marshall The Pig (Marshall Three Knob) Preamplifier is nowhere near as well as the schematics of classic amplifiers.

Generally speaking DIY amplifier must be absolutely clean amplifier without any effects loops, without any mods.

Only when the amplifier is running, when he suffers and survives the "baptism of fire" could think modification like 6L6 vs. EL34, and/or triode vs. pentode.

Effects loops forget at start, because they are located between the preamp and power amp, where are Hi level signals about 1 to 2 V, and the effects that guitarists use (ground effects) can not transfer and quickly go into overdrive. About effect loops as part of the amplifier can be considered only if they are used studio effects that are designed to work with the of Hi level signals.

Good luck

About my knowledge language https://translate.google.com

sorry

vk

[Archie Speed]

Again, thanks for the interest & responses. I'm guessing that this thread is going to morph away from Vintage Amps into New or Kit Build territory.

Whatever I do with this is going to involve simplicity. I don't want to dump a bunch of $$$ into it & I rather prefer the sound of a simple, vintage Bassman or Marshall. Don't want effect loops. I just use whatever the amp brings + an attenuator. Maybe an od pedal on occasion. Basic. I'm also glad to be able to work on something that isn't solid state.

The Bassman has an allure because I had one (new) back in '65. Had. Nostalgia thing. 4 ea EL34's? Maybe a JCM800 would be more appropriate. Something new & challenging? Maybe. Ideas? This is still a blank canvas for me. I'm open to suggestion.

52 Bill - I'm impressed that you remember such detail from the 70's. There are huge gaps in my memory banks from that era. My compliments.

VK - No translator needed. I 'communicate' with quite a few folks each day that claim English as their native language & I can't understand much of what they are trying to get across. You? You I understand clearly. My thanks for your comments.

Regards,

Archie

[trobbins]

Until you know more about TNT origins, I wouldn't just assume its diy too quickly. TNT may have started fairly low-key, eg. as a service shop, and this could be an early model before they started to make batches. The hole plugs all look original, and there are no markings where pots may have previously been used. I'd recommend trying to eek out more history before ripping it apart with a new clone in mind. Perhaps at least sketch the circuit and test the transformers for voltages and likely impedance levels, and post here so that someone in the future can use the photos and info as a resource. Eg. if you found that later model TNT were well regarded and of interest, then you could restore as a later model TNT.

Ciao, Tim

[Justin Thomas]

Agreed - find more info first. And if you DO go with a Bassman, do an AB165 preamp... jump the channels together! There's an Earth amp schemo floating around that's a 100W power amp w AB165 pre...

Justin