[whirlwind]

I have the 5998 switch on my GOTL.

I have not used it in quite some time though.

 

[Xcalibur255]

Honestly neither have I, but that's mostly because the 5998 is so expensive to replace now and the headphones I use with the amp these days have better synergy with tubes like the RCA 6AS7.

 

[Paladin79]

Honestly neither have I, but that's mostly because the 5998 is so expensive to replace now and the headphones I use with the amp these days have better synergy with tubes like the RCA 6AS7.

There have been some NOS GE 5998A's available for very little money. Several friends tried them and many liked the tube because of how it sounded with low frequencies. There were a couple that had to have the pins re-soldered, the gentleman selling them had no way to test them but they were new in the box. I got one for $25 and later paid around $40 each.

 

[Xcalibur255]

It was my understanding that the 5998A is not equivalent to the 5998? It's been quite a few years now since I've been in a conversation on the subject so I can't quite recall now.

 

[Zachik]

The GOTL allowed a dizzying array of tubes to be used. The devout tube rollers' dream amp!

Yup. That drove me to create a table of compatible tubes - link is in my signature

 

[mordy]

It was my understanding that the 5998A is not equivalent to the 5998? It's been quite a few years now since I've been in a conversation on the subject so I can't quite recall now.

From the GE 5998-A spec sheet:
"The 5998-A is a low-mu, twin triode designed for service as a series regulator in d-c power supplies. Except for the use of T-12 envelope and a different base, the 5998-A is identical to the 5998."
file:///D:/Downloads/5998A000.pdf
However, based on reading, the GE (and Sylvania) 5998-A never garnered as much enthusiasm as the TS 5998 tube.
Which leads us to the 6AS7GA tube which is supposed to be identical to the 6AS7G but with a straight glass envelope.
Again, to me it does not sound the same as the 6AS7G tube.

 

[Paladin79]

It was my understanding that the 5998A is not equivalent to the 5998? It's been quite a few years now since I've been in a conversation on the subject so I can't quite recall now.

specs are readily available. I use them in amps I made for 6080's and 6as7g's with no issue. I prefer the Tung Sol of course.

 

[raindownthunda]

From the GE 5998-A spec sheet:
"The 5998-A is a low-mu, twin triode designed for service as a series regulator in d-c power supplies. Except for the use of T-12 envelope and a different base, the 5998-A is identical to the 5998."
file:///D:/Downloads/5998A000.pdf
However, based on reading, the GE (and Sylvania) 5998-A never garnered as much enthusiasm as the TS 5998 tube.
Which leads us to the 6AS7GA tube which is supposed to be identical to the 6AS7G but with a straight glass envelope.
Again, to me it does not sound the same as the 6AS7G tube.

I have several Sylvania 5998A and was surprised with how good they sound. Wasn’t expecting much but they stayed in my amp for quite a while. Much more dynamic and richer than the Sylvania 6080. They do sound different to me than the TS 5998.

 

[Paladin79]

From the GE 5998-A spec sheet:
"The 5998-A is a low-mu, twin triode designed for service as a series regulator in d-c power supplies. Except for the use of T-12 envelope and a different base, the 5998-A is identical to the 5998."
file:///D:/Downloads/5998A000.pdf
However, based on reading, the GE (and Sylvania) 5998-A never garnered as much enthusiasm as the TS 5998 tube.
Which leads us to the 6AS7GA tube which is supposed to be identical to the 6AS7G but with a straight glass envelope.
Again, to me it does not sound the same as the 6AS7G tube.

I offered it up as an alternative based on price and availability, I have not bought one for about a year. For higher gain there is always the Cetron 7236. My preferences on 6AS7G's are the Chatham bottom getters, along with some vintage Winged C's used by the Russian military. According to one friend, the military always got the best products.

 

[sam6550a]

I offered it up as an alternative based on price and availability, I have not bought one for about a year. For higher gain there is always the Cetron 7236. My preferences on 6AS7G's are the Chatham bottom getters, along with some vintage Winged C's used by the Russian military. According to one friend, the military always got the best products.

The only significant difference is in transconductance, with the 5998 at 14000 umho, and the 5998A at 15500 umho. I think that the 5998A is a fine, low cost alternative to other 6AS7/6080 variants. Of course, others may disagree.

 

[Xcalibur255]

From the GE 5998-A spec sheet:
"The 5998-A is a low-mu, twin triode designed for service as a series regulator in d-c power supplies. Except for the use of T-12 envelope and a different base, the 5998-A is identical to the 5998."
file:///D:/Downloads/5998A000.pdf
However, based on reading, the GE (and Sylvania) 5998-A never garnered as much enthusiasm as the TS 5998 tube.
Which leads us to the 6AS7GA tube which is supposed to be identical to the 6AS7G but with a straight glass envelope.
Again, to me it does not sound the same as the 6AS7G tube.

Yeah, that's jogging my memory a little. It's not a spec thing, what I meant was that people seemed to think they didn't sound as good. I haven't compared myself so I don't have a personal opinion on it.

 

[bcowen]

There have been some NOS GE 5998A's available for very little money. Several friends tried them and many liked the tube because of how it sounded with low frequencies. There were a couple that had to have the pins re-soldered, the gentleman selling them had no way to test them but they were new in the box. I got one for $25 and later paid around $40 each.

I agree that the GE 5998A is a good $25 tube.

 

[Paladin79]

Yeah, that's jogging my memory a little. It's not a spec thing, what I meant was that people seemed to think they didn't sound as good. I haven't compared myself so I don't have a personal opinion on it.

I am talking about a minimum of ten people who have heard them and had positive comments. I can include @bcowen I suppose, if I have to.
Unfortunately he has a negative expectation bias where GE is concerned.

 

[bcowen]

I am talking about a minimum of ten people who have heard them and had positive comments. I can include @bcowen I suppose, if I have to.
Unfortunately he has a negative expectation bias where GE is concerned.

Huh? I don't suffer from expectation bias. I know how things are supposed to sound before I even hear them.

 

[Paladin79]

Huh? I don't suffer from expectation bias. I know how things are supposed to sound before I even hear them.

I stand corrected, sort of.
I could send you mini radials to sample but you must already know what they sound like without hearing them.