Different tubes in the OR-15

[guitfiddle]

I put an old RCA with short black plates in V1, and a Tubestore 7025 in V2.

Wow.

It cleared up the tone; there is less high end fizz and more meat in the midrange. There is a tad less gain at any given setting than before, but the quality of the harmonics in the OD has gone up tremendously. The stage volume tones are just inspiring now, and I absolutely loved this amp before this improvement. There is just an overall higher quality level to the amp's sound now.

Some amps don't respond as favorably to a quality tube like the RCA, but this one certainly did.

My next goal is some NOS power tubes, maybe some Mullards.

 

[FuseG4]

Re: Different tubes in the OR-15

Nice. The NOS power tubes will probably make the same kind of difference, even if you don't spring for mullards.

Matsush1ta was largely tooled by mullard and they made a nice el84.

 

[guitfiddle]

Re: Different tubes in the OR-15

Nice. The NOS power tubes will probably make the same kind of difference, even if you don't spring for mullards.

Matsush1ta was largely tooled by mullard and they made a nice el84.

That is good to know...they might be cheaper and easier to find.

 

[FuseG4]

Re: Different tubes in the OR-15

That is good to know...they might be cheaper and easier to find.

yeah that was they main reason I looked into them, I can't afford to spend a ton, but yeah they did a great 12ax7 as well. When I had a Night Train 15 I had matsu 12ax7 and el84 and it was a little bright but took all the nasally and most of the fizzy quality out
They used to be dirt cheap and a sort of hidden gem but they're still pretty inexpensive

 

[Swampy]

Re: Different tubes in the OR-15

I put an old RCA with short black plates in V1, and a Tubestore 7025 in V2.

Wow.

It cleared up the tone; there is less high end fizz and more meat in the midrange. There is a tad less gain at any given setting than before, but the quality of the harmonics in the OD has gone up tremendously. The stage volume tones are just inspiring now, and I absolutely loved this amp before this improvement. There is just an overall higher quality level to the amp's sound now.

Some amps don't respond as favorably to a quality tube like the RCA, but this one certainly did.

My next goal is some NOS power tubes, maybe some Mullards.

I want to try this. Any links on where you got your tubes? Thanks!

 

[guitfiddle]

Re: Different tubes in the OR-15

I want to try this. Any links on where you got your tubes? Thanks!

Unfortunately not. The RCA was a gift from a friend who was getting out of playing. He gave it to me along with three(!!!) Telefunken 12AX7s.

Someone on TGP told me that RCA never made a 12AX7 with short black plates...he said it was most likely a 5751, which is about 70% gain compared to the 12AX7 that was in there. That's just a bit more than a 12AT7. I dig it.

You CAN buy new 5751 tubes, they just won't be NOS

 

[Darg1911]

Re: Different tubes in the OR-15

Unfortunately not. The RCA was a gift from a friend who was getting out of playing. He gave it to me along with three(!!!) Telefunken 12AX7s.

Someone on TGP told me that RCA never made a 12AX7 with short black plates...he said it was most likely a 5751, which is about 70% gain compared to the 12AX7 that was in there. That's just a bit more than a 12AT7. I dig it.

You CAN buy new 5751 tubes, they just won't be NOS

If it's got short black plates and 3 mica spacers, it's most likely a 5751.

Word is that there are no current production 5751's being made. The current production 5751's are 12AX7's that tested low for GM. Been told this by two reputable dealers. I cant say it's 100% true but I believe it.

 

[FuseG4]

Re: Different tubes in the OR-15

If it's got short black plates and 3 mica spacers, it's most likely a 5751.

Word is that there are no current production 5751's being made. The current production 5751's are 12AX7's that tested low for GM. Been told this by two reputable dealers. I cant say it's 100% true but I believe it.

I can believe it,
One thing I also heard is that most new 12ax7 test well below gain factor of 100, old tubes had this too but not as bad, but yeah in order to get the gain factor you would expect from old 12ax7 you ought to get a new 12ax7 tested "high gain". Like today's "high gain" tubes are yesteryear's normal ones.
Anyone else heard this, it seems plausible
But I can imagine different shops calling high gain different things. Maybe some say it's the highest x% of the sample they have on hand. Maybe others say a tube is high gain when it has a certain GM or gain factor?

 

[Darg1911]

Re: Different tubes in the OR-15

I can believe it,
One thing I also heard is that most new 12ax7 test well below gain factor of 100, old tubes had this too but not as bad, but yeah in order to get the gain factor you would expect from old 12ax7 you ought to get a new 12ax7 tested "high gain". Like today's "high gain" tubes are yesteryear's normal ones.
Anyone else heard this, it seems plausible
But I can imagine different shops calling high gain different things. Maybe some say it's the highest x% of the sample they have on hand. Maybe others say a tube is high gain when it has a certain GM or gain factor?

That's reportedly true. Some of this is old but from a reputable dude. http://la-economy.blogspot.com/2013/05/current-production-12ax7-tubes-ten-of.html

http://guitaramplifierblueprinting.com/12ax7.html

 

[Gtrjunior]

Re: Different tubes in the OR-15

Unfortunately not. The RCA was a gift from a friend who was getting out of playing. He gave it to me along with three(!!!) Telefunken 12AX7s.

Someone on TGP told me that RCA never made a 12AX7 with short black plates...he said it was most likely a 5751, which is about 70% gain compared to the 12AX7 that was in there. That's just a bit more than a 12AT7. I dig it.

You CAN buy new 5751 tubes, they just won't be NOS

Yeah, I’ve never heard of a short black plate RCA either. Only grey. I have several of each....the grey plate sound damn good too.