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For 6AS7G tube rollers here .....

post #1 of 1561
Thread Starter 
tried to put together some 6AS7G equivalents with notes (from my personal experience). of course, the usual brand/re-label disclaimers apply. So no need which one is better. The goal here is just to list the main equivalents that may work in your amp's circuit. Did I miss any equivalents?


6080 - low gain @ 2- great vocals, wide soundstaging

7236 - medium gain - great bass, fast and dynamic. Almost SS sounding

5998A - medium gain in straight bottle. Plate construction like 6AS7.

5998 - medium gain at 5, full-bodied sound, same current load as 6AS7

421A - same as 5998 but with matched plates/sections

6AS7G - low gain, the standard tube for most, plentiful

6AS7GA - low gain, like the standard 6AS7G in striaght bottle

6520 - premium 6SA7G, sometimes with 5998 plates

6H13 - russian 6AS7G equivalent. nothing magical with these

ECC230 - european 6AS7G equivalent. haven't seen one in person

6528 - equiv to 5998 but very high gain at 9, twice the current load. Make sure you amp can handle it

6336 - like 6528 but low gain at 2, still twice current load. Make sure you amp can handle it

post #2 of 1561
Like you said at the top, this is what you experienced with you amp and input tube.

So as far as your description of sound though, that is very dependent on the input tube (and presumably the amp as well.)

For example with the 2c51 input, the 6AS7G's had a weird soundstage and sounded poor in my Extreme. But with the Tung Sol 5998's it was very natural and powerful.

But with some 12AT7's the 5998's sounded way too forward and bright, but were more natural with the 6AS7G's.


I think there is a 6080W also.
And the 2399.
post #3 of 1561
Oh, and I just talked with Mikhail today. He said he's developing a new adapter for the Extreme output socket so that it can handle a very different tube type -- I don't remember which tube it was though.
post #4 of 1561
Quote:
Originally Posted by bdh View Post
Oh, and I just talked with Mikhail today. He said he's developing a new adapter for the Extreme output socket so that it can handle a very different tube type -- I don't remember which tube it was though.
4X150A/ 7034/ CV2519 run VERY conservatively in the Extreme for 2.3 watts per channel.

Heater voltage 6V
Heater current 2.6A
Max negative control grid voltage -250V
Max input control grid 2W
Max heater/cathode voltage +/-150V
Max anode core temperature 250C
Max anode seal temperature 200C
Max base seal temperature 175C
Max altitude 10,000 feet
Min cathode heating time 30 secs

Class AB audio
Max anode voltage 2kV
Max anode dissipation 250W
Max anode input 500W
Max anode current 250mA
Max screen voltage 400V
Max screen dissipation 12W









post #5 of 1561
Quote:
Originally Posted by bdh View Post
Like you said at the top, this is what you experienced with you amp and input tube.

So as far as your description of sound though, that is very dependent on the input tube (and presumably the amp as well.)

For example with the 2c51 input, the 6AS7G's had a weird soundstage and sounded poor in my Extreme. But with the Tung Sol 5998's it was very natural and powerful.

But with some 12AT7's the 5998's sounded way too forward and bright, but were more natural with the 6AS7G's.


I think there is a 6080W also.
And the 2399.
The 6080W is about the same as the 6080 just a different manufacturing era .... there is the 6080WA /B /C.

The 2399 is a better quality 6AS7G with tighter section matching and apparently the ability to handle higher plate current. This tube in the pic has the plates that look like the 5998 plates .... which makes sense since most 5998s were made by TS and this example is a TS 2399. This tube is possibly almost identical to some of the 6AS7s with the 5998 plates. But, I think this tube sounds the same as all my other TS 6AS7s. Personally, unless you need more gain I like the 6AS7G as well as any tube in this series.

post #6 of 1561
Some comments from my experience in my WA2:

Quote:
6080 - low gain @ 2- great vocals, wide soundstaging
I'd love to know, but it did not fit in the amp (even though the socket is labeled 6080

Quote:
5998A - low gain in straight bottle. Plate construction like 6AS7. nothing special.
I got a pair of NOS GE 5998A's with the amp, and I must admit I really like them. Slightly forward vocals and not the widest soundstage, but overall a very clear/clean/crisp sound.

Quote:
5998 - medium gain at 5, full-bodied sound, same current load as 6AS7
Agreed, very nice. Has some excellent low-down control and texture too.

Quote:
6AS7G - low gain, the standard tube for most, plentiful
Have not tried any yet. Unfortunately Skylab has me chasing down ghosts - I am trying to find a NOS pair of GEC/Marconi brown-based tubes to pop my 6AS7G cherry

I second the comment that it also depends a lot on the other tubes in the complement. I found that rolling the 6922/6DJ8 preamp tube yielded a more significant impact.
post #7 of 1561
Thread Starter 
you mean a brown base 6as7g like this?

post #8 of 1561
Quote:
Originally Posted by sacd lover View Post
4X150A/ 7034/ CV2519 run VERY conservatively in the Extreme for 2.3 watts per channel.

Heater voltage 6V
Heater current 2.6A
Max negative control grid voltage -250V
Max input control grid 2W
Max heater/cathode voltage +/-150V
Max anode core temperature 250C
Max anode seal temperature 200C
Max base seal temperature 175C
Max altitude 10,000 feet
Min cathode heating time 30 secs

Class AB audio
Max anode voltage 2kV
Max anode dissipation 250W
Max anode input 500W
Max anode current 250mA
Max screen voltage 400V
Max screen dissipation 12W











OH GOD WHAT IS IT
post #9 of 1561
Ha that thing looks like a commercial jet engine.
post #10 of 1561
Quote:
Originally Posted by sacd lover View Post
Personally, unless you need more gain I like the 6AS7G as well as any tube in this series.
I agree with this. I do think the Tung-Sol 6AS7G's sound a little better than the RCA's, and I think the GEC brown-base UK ones sound a little better still, but I don't think the differences are so huge that they are worth dealing with unless you are a psychotic tube collector...like me

Quote:
Originally Posted by xenithon View Post
Unfortunately Skylab has me chasing down ghosts - I am trying to find a NOS pair of GEC/Marconi brown-based tubes to pop my 6AS7G cherry
HA! And yeah, this is my favorite of all of these tube types, no doubt.

Quote:
Originally Posted by glitch39 View Post
you mean a brown base 6as7g like this?

YEP - that is the one. Has a slightly different plate structure than your typical US made 6AS7G.

To the OP: There is also the 6AS7GA, and 6AS7GYB. The GA is a straight-bottle 6AS7G, with black base; the GYB has a brown base. AFAIK, both were only made by GE.
post #11 of 1561
Skylab - should you ever come across any NOS pairs of those I beg of you to alert me . I've been looking out for a few months now; there is one on eBay but only one (need a pair) and the seller hasn't got any others
post #12 of 1561
There was a guy in the UK selling a whole bunch of these NOS for a while - but he must have sold out, since he doesn't seem to offer them now, although he has lots of other tubes for sale still. Yes, I will let you know if I see more of them for sale.
post #13 of 1561
scootermafia,

it looks to me like a space heater. One will take care of a small room - two for larger spaces (above 850 sq. feet). Order now, and you can get a hand-made Amish wooden mantel / case.
post #14 of 1561
I read somewhere (google search) that all 5998 tubes are made by Tung-Sol, even if branded differently. Can anyone verify this? These are hard to find for sale... anyone know of a good source?
post #15 of 1561
It's true. Only Tung-Sol made the 5998. You see them branded Chatham (which was bought by Tung-Sol), and IBM, and of course the most famous branding was the Western Electric 421a, but even these are 100% identical to the Tung-Sol 5998.

GE did make a "5998A", but this is a different tube. It has a plate structure more like a 6AS7 than the 5998, and is in a straight-bottle. They also sound nowhere near as good as the TS 5998.
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