NOS RFT EL34's manufactured in the early 60'

[novosibir]

Santa Claus was already here on last Tuesday...
... and he brought me 60 new tubes in their original packaging
But not just any tubes, but good old NOS RFT EL34's from former East German production.
But not the relatively unreliable RFT's from the late 80's productions
Not even the very reliable RFT's from the late 60's to mid 80's productions
But the extremely reliable RFT's from early 60' productions - recognizable by the slightly flatter tube base compared to later productions.
In addition, the tubes are provided with the printed number "1" in the triangle, which means that they are selected first-class export quality

Every insider knows that next to the legendary Mullard EL34 the East German RFT EL34 is the best sounding EL34 ever produced

I still can't quite believe that I was given such a princely gift and I have to admit that I was starting to doubt whether Santa Claus really exists...
... but that's the proof that Santa Claus really exists

But now look what I got:

And woohoo - they are measuring great. Very strong tubes

This ensures the supply of the next 15 Larry amps with unrivalled great & reliable power tubes

To put it in concrete terms - for the next 15 Larry amps, which will be added to my list as an order after I have finished my order stop again, because for the currently ordered but not yet built Larry amps all the necessary NOS Tungsram ECC83's and NOS RFT EL34's are already sitting on the shelf.

 

[Hiwatts-n-Gibsons]

Santa Claus was already here on last Tuesday...
... and he brought me 60 new tubes in their original packaging
But not just any tubes, but good old NOS RFT EL34's from former East German production.
But not the relatively unreliable RFT's from the late 80's productions
Not even the very reliable RFT's from the late 60's to mid 80's productions
But the extremely reliable RFT's from early 60' productions - recognizable by the slightly flatter tube base compared to later productions.
In addition, the tubes are provided with the printed number "1" in the triangle, which means that they are selected first-class export quality

Every insider knows that next to the legendary Mullard EL34 the East German RFT EL34 is the best sounding EL34 ever produced

I still can't quite believe that I was given such a princely gift and I have to admit that I was starting to doubt whether Santa Claus really exists...
... but that's the proof that Santa Claus really exists

But now look what I got:


View attachment 427161


View attachment 427162


View attachment 427163


And woohoo - they are measuring great. Very strong tubes


View attachment 427164


View attachment 427166



This ensures the supply of the next 15 Larry amps with unrivalled great & reliable power tubes

Damn, I would love to get a quad of those for my Reeves Custom 100 to go with the Mullard EL34's in my Hiwatt Custom 100.

Awesome score man.

 

[Geo]

I have a set in my Metro build from the year 2000ish.

The set cost me $225 back then, which seemed kinda pricey at the time but they have been super reliable and sound great.

 

[novosibir]

I have a set in my Metro build from the year 2000ish.

The set cost me $225 back then, which seemed kinda pricey at the time but they have been super reliable and sound great.

Yes these RFT EL34 have an almost unlimited lifespan, similar to the RCA 6L6GC black plate output tubes from the 60'

The purchase price is high, very high even compared to the price of tubes currently produced in the Czech Republic, Russia or in China.

However, if you consider that with a set of NOS output tubes you save up to 10 or even more tube changes when using currently produced tubes, then from an economic point of view you have actually saved yourself a lot of money over time.

There is additional the advantage that NOS tubes sound remarkably better and are significantly more reliable than any tubes currently being produced.

And - nothing is more embarrassing than when your amp suddenly dies on stage in the middle of your most beautiful solo because another power tube fails due to a short and the amp's fuse blows.

 

[Geo]

Yes these RFT EL34 have an almost unlimited lifespan, similar to the RCA 6L6GC black plate output tubes from the 60'

The purchase price is high, very high even compared to the price of tubes currently produced in the Czech Republic, Russia or in China.

However, if you consider that with a set of NOS output tubes you save up to 10 or even more tube changes when using currently produced tubes, then from an economic point of view you have actually saved yourself a lot of money over time.

There is additional the advantage that NOS tubes sound remarkably better and are significantly more reliable than any tubes currently being produced.

And - nothing is more embarrassing than when your amp suddenly dies on stage in the middle of your most beautiful solo because another power tube fails due to a short and the amp's fuse blows.

When I bought those tubes, the seller told me I should keep the plate voltage below 400v. I have no idea why he would say that to me, I was new to the whole amp building/retubing thing. Any idea why he would say that? The plates are running about 540v which is well in spec for those tubes. And no issues at all.

 

[novosibir]

When I bought those tubes, the seller told me I should keep the plate voltage below 400v. I have no idea why he would say that to me, I was new to the whole amp building/retubing thing. Any idea why he would say that? The plates are running about 540v which is well in spec for those tubes. And no issues at all.

The statement with "keep the plate voltage below 400V" is definitely wrong!

The fact is that good RFTs can tolerate up to 550V on the plates in push-pull A/B mode and up to over 800V on the plates in push-pull B mode.

By 'good' I mean all RFT productions up to 1986
From the years 1987 until the factory closed in 1989, the reliability and electrical strength became noticeably worse and the tolerances increased, as from 1987 onwards the machines were no longer maintained, from 1988 onwards inferior materials were used and the vacuum in the tubes was no longer of the same quality as it used to be earlier.

From the 1987 production onwards I would no longer exceed a plate voltage of 450V.

Too many RFT EL34s from the last production batches died in the past in my amps and sometimes already on the tester.

 

[Geo]

The statement with "keep the plate voltage below 400V" is definitely wrong!

The fact is that good RFTs can tolerate up to 550V on the plates in push-pull A/B mode and up to over 800V on the plates in push-pull B mode.

By 'good' I mean all RFT productions up to 1986
From the years 1987 until the factory closed in 1989, the reliability and electrical strength became noticeably worse and the tolerances increased, as from 1987 onwards the machines were no longer maintained, from 1988 onwards inferior materials were used and the vacuum in the tubes was no longer of the same quality as it used to be earlier.

From the 1987 production onwards I would no longer exceed a plate voltage of 450V.

Too many RFT EL34s from the last production batches died in the past in my amps and sometimes already on the tester.

Thanks for the info.

I will have to check the date codes. I have quite a few hours on them now and they owe me nothing but if they were made between 87 and 89 maybe I should move them to a different amp just for the sake of being safe.

 

[novosibir]

Are yours RFT labelled or do they wear a different brand's name?

 

[Geo]

Are yours RFT labelled or do they wear a different brand's name?

Can't get to the amp right now but I saved the boxes and the description form ebay.

 

[novosibir]

Richardson labels the tubes "National" and the boxes say 9/87

Check the description!

"These tubes were purchased in quantity from a military base surplus auction some years ago..."

Hence they probably are from between 1983 & 1985 production.
In addition, you have proof that they have tolerated 540V plate voltage so far.
The bad later productions would have died with 540V on the plates within max. 10 minutes.

Check also my post here from 16 years ago: RFT EL34 usable in Modern Classic ?

 

[Geo]

Richardson labels the tubes "National" and the boxes say 9/87

Check the description!

"These tubes were purchased in quantity from a military base surplus auction some years ago..."

Hence they probably are from between 1983 & 1985 production.
In addition, you have proof that they have tolerated 540V plate voltage so far.
The bad later productions would have died with 540V on the plates within max. 10 minutes.

Check also my post here from 16 years ago: RFT EL34 usable in Modern Classic ?

Thanks, will do, I love to learn.

And know that I know a bit more about these things I can see why the description mentions the JCM800 in particular.

 

[novosibir]

Damn, I would love to get a quad of those for my Reeves Custom 100 to go with the Mullard EL34's in my Hiwatt Custom 100.

Sorry no, these tubes are all exclusively for my own amps.

But I still have 36 pcs. NOS Mullard EL34 - Xf2 double ring getter, Xf2 single ring getter, Xf3 & Xf4
Most of them are labelled Valvo or Philips.
If you're interested?

But be warned - these would cost you an arm & a leg, or your firstborn

 

[Hiwatts-n-Gibsons]

Sorry no, these tubes are all exclusively for my own amps.

But I still have 36 pcs. NOS Mullard EL34 - Xf2 double ring getter, Xf2 single ring getter, Xf3 & Xf4
Most of them are labelled Valvo or Philips.
If you're interested?

But be warned - these would cost you an arm & a leg, or your firstborn

As much as I would love to get my hands on those too I can't afford to be spending money on gear right now. I did a couple pretty stupid things a couple years ago, and am currently just trying to get back on my own two feet.

That's why I didn't ask about the RFT's.

 

[novosibir]

As much as I would love to get my hands on those too I can't afford to be spending money on gear right now. I did a couple pretty stupid things a couple years ago, and am currently just trying to get back on my own two feet.

Oh, I'm sorry for you and wish you a lot of strength!

 

[FourT6and2]

In addition, the tubes are provided with the printed number "1" in the triangle, which means that they are selected first-class export quality

 

[FourT6and2]

The statement with "keep the plate voltage below 400V" is definitely wrong!

The fact is that good RFTs can tolerate up to 550V on the plates in push-pull A/B mode and up to over 800V on the plates in push-pull B mode.

What about the screens?

 

[novosibir]

View attachment 429241

That's the info I published here in another thread 16 years ago. Here:

Check also my post here from 16 years ago: RFT EL34 usable in Modern Classic ?

 

[novosibir]

What about the screens?

I had no failures with RFT EL34 from the 60's and 70's in early 70's Marshall amps with 530 volts on the plates and 520 volts on the screens.

However, you have to make sure that there is no oscillation in the power amp section, what is unfortunately often the case with these models because of the sloppily executed lead dress.

In order to exclude or eliminate oscillation, the following conditions must be met:
- never bundle the OT's primaries and secondaries together! Bundle them separately and keep a distance between both bundles of at least 5/8 inches.
- drill the red & brown OT's primaries together and have the white CT primary undrilled in the bundle.
- never have the violet precence cable in the primary's bundle, even avoid to cross it anywhere with the primaries
- you can bundle the violet cable with the secondaries, but best have it completely separate far away from the primaries.
- use 1k/7W screen grid resistors.
- have at least 5.6k grid stoppers on the output tube sockets, but 10k, 12k or even 22k grid stopper are still safer and don't influence the sound.
- have (what's valid also for the cables to the preamp sockets) all cables as long as required, but as short as possible!
- check how much excess cable length has been pushed under the board and shorten all cables according to my recommendation above.

 

[FourT6and2]

- have at least 5.6k grid stoppers on the output tube sockets, but 10k, 12k or even 22k grid stopper are still safer and don't influence the sound.

Won't this exceed the maximum grid leak resistance spec for EL34? I mean... stock Marshalls already kind of do this anyway with 220K PI output grid leak resistance + 5K6 grid stoppers. I don't think anybody really pays attention to this. Does it even matter?

 

[novosibir]

Won't this exceed the maximum grid leak resistance spec for EL34? I mean... stock Marshalls already kind of do this anyway with 220K PI output grid leak resistance + 5K6 grid stoppers. I don't think anybody really pays attention to this. Does it even matter?

Oh forgot to mention, that I always swap the grid leak resistors with 100k in the 4-cyl. 100 watts models and use a strong ECC83 in the PI spot, usually a Yugo EI or a smooth plate Telefunken.