I Love My Quirky Vintage Tube Amps....But Hate The Weird Tubes They Use

guitarcapo

Senior Member
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2,326
6973, 7189A,6EU7,12DW7,6CZ5,6CG7,12BH7,6DR7


What a pain.

I wonder how many of these tubes are routinely thrown out by people who only care about 12A?7, and standard power and rectifier tubes?
 

guitarcapo

Senior Member
Messages
2,326
Magnatones mostly. They sound great. Here's a Demo of a 280B of mine. Uses four 6973 power tubes, 12BH7 and three 6CG7. Weird juke box tubes.





Here's a 410. Simple 5 watt amp. Shouldn't be too complicated right? I mean it's basically a Vibro Champ. But NO! I have to track down a 12DW7 tube to make it work:



You can hear my wife taunting me about my new "toy" in this demo
 
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guitarcapo

Senior Member
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2,326
The 7189a isn't that weird. Readily available.
Yea but not cheap. Electro Hamonix came out with one recently but NOS is usually $35+ per tube (used pulls maybe $10 cheaper). The 280 needs 4 of them so I'm already at $140+ for tubes. Just the 4 power tubes...I'm not even counting all the others in there. Fortunately I discovered a tube that's close that sells for $3 a tube: 6EM5. Apparently if I jumper two lugs on the inside of my amp, it can use EITHER a 7189a OR a 6EM5. It's possible that this mod isn't even needed. We'll see. I ordered 10 of them. What the heck it's a gamble but a whole lot of 10 costs less than one NOS 7189a tube. They probably can't handle the plate voltage but I'll give them a try.
 
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flywheel

Member
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435
Yea but not cheap. Electro Hamonix came out with one recently but NOS is usually $35+ per tube (used pulls maybe $10 cheaper). The 280 needs 4 of them so I'm already at $140+ for tubes. Just the 4 power tubes...I'm not even counting all the others in there. Fortunately I discovered a tube that's close that sells for $3 a tube: 6EM5. Apparently if I jumper two lugs on the inside of my amp, it can use EITHER a 7189a OR a 6EM5. It's possible that this mod isn't even needed. We'll see. I ordered 10 of them. What the heck it's a gamble but a whole lot of 10 costs less than one NOS 7189a tube. They probably can't handle the plate voltage but I'll give them a try.
Its worth retubing just for the tremolo
Nice Videos
 

chrisrocksusa

Member
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2,311
Yeah what's the deal w vintage amps, it's hard to find tubes for them? Surely there are companies reproducing old tubes to keep these bad boys rocking
 

zenitB

Silver Supporting Member
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1,527
I had a Bogen PA amp that used 6973's. They are, as you point out, used in juke boxes and I think some Fisher amps. NOS was sometimes pricey but not any more expensive than a good 6V6. After I found some good used ones, one of the Russian plants started making them again - I tried them as well and they were as good as the vintage tubes.
Some of the other oddball tubes like the 12DW7 are often sold cheaply due to lack of demand and the fact that they are NOT 12AX7, 6V6, EL34 and all the other 'popular' types
 

guitarcapo

Senior Member
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2,326
I think I might try those Russian Electro Harmonix 6973. I found a source for them at $22 a pop. $88 for the 4 in the amp's power section.
 

Leonc

Wild Gear Hearder
Platinum Supporting Member
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18,260
The thing I noted with 7189As in Magnatones, at least IME, is that you really have to use the GEs. I don't think anyone else made real "As" where there's an internal connection between pins 6 and 9 (IIRC). The Maggies I've had (suitcase models) that used them were wired to take advantage of this. If I tried using other brands of 7189s (or other EL84-like tubes that could handle the voltage...some kind of Russian military tube, IIRC) that didn't have that connection, the amps didn't perform that well. So I'd wind up shelling out the big bucks for good GA 7189As. Rather expensive indeed but they always sound best.
 

support

Senior Member
Messages
774
The 12DW7 is a dual triode with a low gain triode and a medium gain triode. It's sort of like half 12AT7 and half 12AU7. The low gain side is the trem voltage amp. The medium gain side is the trem oscillator. I would try either an AT or an AU if I was interested in experimenting. Both will change the gain and trem operation. One may not trem. Won't hurt anything to try. Then again, one good DW will last a long time, so it's probably not a big maintenance issue - and you can steal one out of your bass players SVT. He's too damn loud anyway.
 

chrisrocksusa

Member
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2,311
wow, that's a ******* shame. Why wouldn't modern tube companies start making old style tubes?

I can't imagine a world where vintage amps can no longer be played.
 

SatelliteAmps

Member
Messages
6,170
wow, that's a ******* shame. Why wouldn't modern tube companies start making old style tubes?

I can't imagine a world where vintage amps can no longer be played.
Because the cost of making the tubes isn't worth it.

The good thing is that all of these tubes can be found in vintage styles, or they can be resocketed to use currently made tubes. The tubes listed aren't really that odd, just a different style than others. They are still standard triodes, and pentodes.
 

guitarcapo

Senior Member
Messages
2,326
Well I COULD rewire this amp to take EL84 tubes. That would be a desperation move. Sort of like putting a new engine in your antique model T because you can't find parts anymore.

Another option is to fashion some sort of adapter to account for the pin out differences.

What someone REALLY needs to make is a sort of universal adapter that can be internally wired by the user to be used for adapting different tube pinouts.

Say I want an adapter that will allow me to use a 6EU7 in place of a 12AX7...because modern 12AX7 are easier to find.
Or maybe the opposite: I have a whole gross of 6EU7 that cost me nothing compared to vintage 12AX7 and I want to use them in my amps...so I need an adapter that will convert the other way.

Anyway I buy this gizmo that I hand wire myself to do either task. An adapter that can convert any tube to another pin out. Someone needs to make that gizmo.
 

Leonc

Wild Gear Hearder
Platinum Supporting Member
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18,260
Yeah, hear you but, man, I wouldn't rewire them!! That's like giving McMurphy the ******* lobotomy, LOL -- I ain't no Nurse Ratched!! I think that if you really love the amps, you just have to buckle up pay the price for good, old stock tubes. Hell they'll probably last until we're dead anyways, LOL. Anyway, that's the route I've chosen to go with mine...
 

support

Senior Member
Messages
774
Well I COULD rewire this amp to take EL84 tubes. That would be a desperation move. Sort of like putting a new engine in your antique model T because you can't find parts anymore.

Another option is to fashion some sort of adapter to account for the pin out differences.

What someone REALLY needs to make is a sort of universal adapter that can be internally wired by the user to be used for adapting different tube pinouts.

Say I want an adapter that will allow me to use a 6EU7 in place of a 12AX7...because modern 12AX7 are easier to find.
Or maybe the opposite: I have a whole gross of 6EU7 that cost me nothing compared to vintage 12AX7 and I want to use them in my amps...so I need an adapter that will convert the other way.

Anyway I buy this gizmo that I hand wire myself to do either task. An adapter that can convert any tube to another pin out. Someone needs to make that gizmo.
A universal adapter would only change pin config. It wouldn't address the need to change circuit values to compensate for the differences in tube operation. I'm not a proponent of changing the circuitry to accept a modern replacement when a reliable original spec part is available, especially when that part, even at NOS pricies, is still cheaper and less time consuming than any of the alternatives discussed here.

BTW, if you have sufficient skill to rewire such a "universal" adapter, you have sufficient skill to build the one you need for less time and money than buying and modifying one.
 

SnidelyWhiplash

Silver Supporting Member
Messages
8,432
Magnatones mostly. They sound great. Here's a Demo of a 280B of mine. Uses four 6973 power tubes, 12BH7 and three 6CG7. Weird juke box tubes.





Here's a 410. Simple 5 watt amp. Shouldn't be too complicated right? I mean it's basically a Vibro Champ. But NO! I have to track down a 12DW7 tube to make it work:



You can hear my wife taunting me about my new "toy" in this demo
Love the 5 watt Mag. Your wife makes it sound all the better.
 




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