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6P3S Tube for Fender Twin
Posted: Tue Mar 12, 2024 4:41 am
by Nudger
Any body had experience with these "6P3S Power tube"
Ive got a twin reverb reissue.. If I bias them correctly, will they be able to handle the plate voltage?
Lots of conficting opinion on the web..
Re: 6P3S Tube for Fender Twin
Posted: Tue Mar 12, 2024 4:42 am
by Nudger
Nudger wrote: ↑Tue Mar 12, 2024 4:41 am
Any body had experience with these "6P3S russian tube"
Ive got a twin reverb reissue.. If I bias them correctly, will they be able to handle the plate voltage?
Lots of conficting opinion on the web..
Re: 6P3S Tube for Fender Twin
Posted: Tue Mar 12, 2024 9:11 am
by GilmourD
Apparently the Sovtek 5881
IS a Reflektor 6P3S.
https://www.diyaudio.com/community/thre ... -e.130254/
It's got 20W maximum dissipation per tube so it'll probably work for a while in an AB763 Twin since that's 85ish watts, but a silver panel at 100W or the UltraLinear 135W Twins will pop those pretty quickly. They're basically the 6L6
G, not the 6L6
GC.
Re: 6P3S Tube for Fender Twin
Posted: Tue Mar 12, 2024 12:42 pm
by Nudger
GilmourD wrote: ↑Tue Mar 12, 2024 9:11 am
Apparently the Sovtek 5881
IS a Reflektor 6P3S.
https://www.diyaudio.com/community/thre ... -e.130254/
It's got 20W maximum dissipation per tube so it'll probably work for a while in an AB763 Twin since that's 85ish watts, but a silver panel at 100W or the UltraLinear 135W Twins will pop those pretty quickly. They're basically the 6L6
G, not the 6L6
GC.
Found this..
https://www.tdpri.com/threads/soviet-6p ... nt.788787/
Not filling me with confidence
Re: 6P3S Tube for Fender Twin
Posted: Tue Mar 12, 2024 2:52 pm
by GilmourD
It's been a couple decades since TDPRI filled me with confidence, but Wyatt is a solid dude with tons of knowledge.
I wouldn't put them in a TRRI. They might be fun in a DRRI, though, since you can sub a 6L6 for a 6V6. Just don't bias it like a 6L6.
Re: 6P3S Tube for Fender Twin
Posted: Wed Mar 13, 2024 3:50 am
by Nudger
Cant find it now but ive only come accross one post where someone was raving about them in his twin, hed biased at 17mA.
Not bothered to much about killing the tubes "only £45".. My main concern is will they take out other components?
Re: 6P3S Tube for Fender Twin
Posted: Wed Mar 13, 2024 7:43 am
by GilmourD
Nudger wrote: ↑Wed Mar 13, 2024 3:50 am
Cant find it now but ive only come accross one post where someone was raving about them in his twin, hed biased at 17mA.
Not bothered to much about killing the tubes "only £45".. My main concern is will they take out other components?
Oh, yeah, catastrophic failure of a power tube has the potential of taking your
output transformer with it.
Re: 6P3S Tube for Fender Twin
Posted: Wed Mar 13, 2024 1:57 pm
by øøøøøøø
6L6GC is rated for 30w max plate dissipation
Don’t use the amp’s rated power output as a guideline for tube plate dissipation
85W is 1% THD
A twin will put out considerably more power than that
Best to stick with 6L6GC when possible
Re: 6P3S Tube for Fender Twin
Posted: Wed Mar 13, 2024 4:10 pm
by GilmourD
øøøøøøø wrote: ↑Wed Mar 13, 2024 1:57 pm
6L6GC is rated for 30w max plate dissipation
Don’t use the amp’s rated power output as a guideline for tube plate dissipation
85W is 1% THD
A twin will put out considerably more power than that
Best to stick with 6L6GC when possible
Yeah, the GC is the way to go with a Twin Reverb. Not a G or a GB, just the GC.
Re: 6P3S Tube for Fender Twin
Posted: Wed Mar 13, 2024 9:33 pm
by øøøøøøø
I was a literal child at the time, but I remember back like 20 years ago people (even print publications) were touting the 5881 as the “military spec 6L6”
This is technically true. 5881 is the military designation for the 6L6GB (or WGB)
Unfortunately, that means a 5881 has at least 30% lower capacity to dissipate power at the plate than a consumer-grade 6L6GC
The folk wisdom that the 5881 would be more robust was a classic case of “just enough knowledge to be dangerous”
I think my first set of Sovtek 5881s as a kid were bought while laboring under this misconception
In fairness to all those who got/get it wrong, it’s not intuitive that 6L6GC would be such a differently-rated tube than a 6L6GB (particularly when people just generically refer to them as “6L6”)
For what it’s worth, the “military-spec” 6L6GC is the 7027A
Re: 6P3S Tube for Fender Twin
Posted: Thu Mar 14, 2024 12:36 am
by matbard
I think it's the 7581A.
The 7027A has different pinout than the 6L6GC
Re: 6P3S Tube for Fender Twin
Posted: Thu Mar 14, 2024 1:36 am
by øøøøøøø
I figured someone might say that
Technically, yes, but in many cases practically no
7027A has two duplicate pins
As long as a 6L6GC amp doesnt use those two pins (unused on 6L6GC) as tie points, the 7027A will plug right in and work great
Or if the amp does use those two locations as tie points, you could just cut those two pins off and the tube will still work fine as a 6L6GC
No warranty for that information!
7581A is also somewhat similar to 6L6GC; IIRC isn’t it more like the KT66?
Re: 6P3S Tube for Fender Twin
Posted: Thu Mar 14, 2024 6:19 am
by GilmourD
øøøøøøø wrote: ↑Thu Mar 14, 2024 1:36 am
I figured someone might say that
Technically, yes, but in many cases practically no
7027A has two duplicate pins
As long as a 6L6GC amp doesnt use those two pins (unused on 6L6GC) as tie points, the 7027A will plug right in and work great
Or if the amp does use those two locations as tie points, you could just cut those two pins off and the tube will still work fine as a 6L6GC
No warranty for that information!
7581A is also somewhat similar to 6L6GC; IIRC isn’t it more like the KT66?
Max plate dissipations:
- 6P3S: 19W (20.5W?)
- 6P3S-E: 20.5W
- 6L6/6L6G/6L6GA: 19W
- 6L6GB: 23W
- 6L6GC: 30W
- 5881: 23W
- KT66: 25W
- 7027A: 35W
- 7581A: 35W
Re: 6P3S Tube for Fender Twin
Posted: Thu Mar 14, 2024 9:49 am
by øøøøøøø
One thing that’s interesting and perhaps relevant:
Occasionally (maybe more than occasionally!) tube manufacturers would find it more economical to make multiple tube models to the same spec, resulting in some designations to have capabilities higher-than-nominal
For instance, it’s almost certainly true that the 1970s JAN/Philips 5881 is actually a 6L6GC in terms of its max plate dissipation. This honestly probably helped perpetuate the misconception that the 5881 could sub in for a 6L6GC
The JAN/Philips 5881 was probably produced in larger numbers than any other 5881, and would do nothing to disabuse the user of the notion that it would work in an amp calling for 6L6GC
Additionally, it’s almost certain that the Sylvania 6L6GC of the 1970s is a 7027A—if you look at both, you’ll plainly see that they’re identical in construction (save the two additional pins on the 7027A that are duplicate connections)
This probably happened countless times
Rather than tooling up to do separate runs of 3-4 different types (presumably with associated tooling and downtime expenses), they’d just tool up for a single construction of the highest spec and run off a whole bunch, slapping different numbers on them
Even in the modern era, I feel almost positive that the JJ 7027A and 6L6GC are the exact same tube
Re: 6P3S Tube for Fender Twin
Posted: Thu Mar 14, 2024 1:12 pm
by GilmourD
øøøøøøø wrote: ↑Thu Mar 14, 2024 9:49 am
One thing that’s interesting and perhaps relevant:
Occasionally (maybe more than occasionally!) tube manufacturers would find it more economical to make multiple tube models to the same spec, resulting in some designations to have capabilities higher-than-nominal
For instance, it’s almost certainly true that the 1970s JAN/Philips 5881 is actually a 6L6GC in terms of its max plate dissipation. This honestly probably helped perpetuate the misconception that the 5881 could sub in for a 6L6GC
The JAN/Philips 5881 was probably produced in larger numbers than any other 5881, and would do nothing to disabuse the user of the notion that it would work in an amp calling for 6L6GC
Additionally, it’s almost certain that the Sylvania 6L6GC of the 1970s is a 7027A—if you look at both, you’ll plainly see that they’re identical in construction (save the two additional pins on the 7027A that are duplicate connections)
This probably happened countless times
Rather than tooling up to do separate runs of 3-4 different types (presumably with associated tooling and downtime expenses), they’d just tool up for a single construction of the highest spec and run off a whole bunch, slapping different numbers on them
Even in the modern era, I feel almost positive that the JJ 7027A and 6L6GC are the exact same tube
And ironically NewSensor made sure that even though they own a bazillion tube brands that none of them share designs despite them being made in the Reflektor factory.