[whirlwind]

My headphone amp uses two #27 drivers and 6H13C
A 5U8C rectifier that can handle the large filter capacitor inrush. I use
massive filtering for B+ and the 2.5 volt DC for the #27s.
No noise is the most important thing that is why I exclusively use the 6H13C outputs.
And have a pair of noise free 27s hard to find.
Hard to believe I am not a tube roller.

You sent me a 5U8C rectifier and adapter with my EL3N amp.
It is a pretty huge rectifier tube.

 

[JazzVinyl]

My headphone amp uses two #27 drivers and 6H13C
A 5U8C rectifier that can handle the large filter capacitor inrush. I use
massive filtering for B+ and the 2.5 volt DC for the #27s.
No noise is the most important thing that is why I exclusively use the 6H13C outputs.
And have a pair of noise free 27s hard to find.
Hard to believe I am not a tube roller.

When you find your sweet combo....stay with it!

 

[attmci]

My headphone amp uses two #27 drivers and 6H13C
A 5U8C rectifier that can handle the large filter capacitor inrush. I use
massive filtering for B+ and the 2.5 volt DC for the #27s.
No noise is the most important thing that is why I exclusively use the 6H13C outputs.
And have a pair of noise free 27s hard to find.
Hard to believe I am not a tube roller.

Saved you tons of hard-earn $$$$$$$$$$$$$.

 

[attmci]

Yes, I have found 6x 6BL/BX7 require very quiet driver tubes.

Less quiet drivers appreciate the much lower gain 6AS7/6080's...or 5998's by themselves. My Chatham 6AS7's sound really dandy, paired with my Mullard 6080's.

My quietest drivers are the 12AU7, a Raytheon 12SN7 and the 1633 and some Raytheon and Sylvania 6SN7's.

Noisy drivers for me are C3g (mine are _very_ microphonic) FDD20 had development a lot of noises. Many vintage 6SN7 are pretty noisy, too, as are my 2x ECC31's, all these are best used with the lower gain power tubes.

But Glenn's amp makes sure you can find a tube combo to suit every driver....

The quietest 12AU7s are those 7316s.
Did you use a 12au7 to 6sn7 adapter?

 

[gibosi]

My headphone amp uses two #27 drivers and 6H13C
A 5U8C rectifier that can handle the large filter capacitor inrush. I use
massive filtering for B+ and the 2.5 volt DC for the #27s.
No noise is the most important thing that is why I exclusively use the 6H13C outputs.
And have a pair of noise free 27s hard to find.
Hard to believe I am not a tube roller.

And of course it is possible to use 27s in the OTL. However, I strongly suspect that Glenn's personal amp, designed from the ground-up to use 27s, is quieter.

 

[2359glenn]

Yes I gone crazy to make it quiet. It uses the same Heybore transformer in your amp.
Has separate filament transformers for the 27s with 4 chokes and a multitude of 22,000 uf caps just for the 2.5 volt filament supply.
2 monster 4,700 uf filter caps for the B+ this is why I need to use the massive 5U8C I originally used a 5U4 and it blue up.
My utmost requirement is quiet I will have a problem if one of these 27s go bad.
I think that the 26 and 27 are the best sounding tubes if you can find quiet ones..

 

[gibosi]

If I ever find myself in your neck of the woods, I would sure like to have a listen.

 

[rnros]

I have been wondering whether Raytheon actually manufactured the 6336 and 6528 or simply rebranded them. Based on your experience, among the US manufacturers, it is beginning to look like Raytheon, Chatham and perhaps RCA manufactured these tubes in the 1960s. But by the 1980s, only Cetron (which purchased Tung-Sol, which purchased Chatham) was making them. But this is still just a guess on my part.

I think you are correct about Cetron and the 6336B in the 1980s. I read that Cetron acquired the Tung-Sol designs in 1975, yet I have seen photos of Cetron 6336Bs dated 1972, but those could be rebranded Tung-Sol. The earliest date I have seen on a 6336B spec sheet is the Tung-Sol dated 1965. Both the Tung-Sol and the Cetron have the same tall bottle design allowing for the revised construction/design below the first stage mica plates, along with other interior revisions. The TS 1965 spec sheet (and photos of 1970 TS 6336B) have ceramic plate stages/mounts, by 1972 the ceramic plates were changed to double stacked mica plates.

There are Raytheon 6336Bs with the earlier short bottle design and interior construction/design similar to the the 'A' version. Perhaps Raytheon was able to meet the military 'B' spec with a simpler revision to the 'A' design?

As far as the earlier 6336 and 6336A versions, there seem to be a number of different manufacturers, or labels, including at least two European brands.

 

[leftside]

It is hard to not go down the tube rabbit hole if you own one of Glenns OTL amps.

These threads are reminding me of what I was like a couple of years ago. It was fun, but hurt my pocket. I now have a nice tube collection though.

 

[leftside]

When you find your sweet combo....stay with it!

Yes.
On the Glenn 300B: Valvo PY500 + Siemen C3G Post + Tak 300B.
On the WA22: TS5998 + Mullard ECC33 + Cossor 53KU. 6BL7/6BX7 for power are also my favorites, but my wife and I don't like the ugly adapters in the living room. Fine in a dedicated music listening room though.

I also like other tubes in the WA22 like the ECC32, B65, and WE421A, but the price makes these more like museum items than something you might actually want to use/blow up.

 

[leftside]

I think you are correct about Cetron and the 6336B in the 1980s. I read that Cetron acquired the Tung-Sol designs in 1975, yet I have seen photos of Cetron 6336Bs dated 1972, but those could be rebranded Tung-Sol.

I have a pair of Western Electric 421A's from 1985.

 

[rnros]

Hi Ros again. You said that 6528 sounds similar to 6336b? Kind of surprising as the 6528 transconductance is so much higher at 37,000 umhos and a mu of 9. Btw the seller is offering the A version and there are 6528, 6528A, 6528B versions.

Here's some data 'borrowed' from another source.

6AS7G/6080 (et al.) u = 2.0 Gm = 7,000 umhos, Pd = 13 W/sect.
5998 u = 5.4 Gm = 15,500 umhos, Pd = 13 W/sect.
5998A u = 5.4 Gm = 15,500 umhos, Pd = 15 W/sect.

6336 u = 2.7 Gm = 11,000 umhos, Pd = 30W/sect.
6336A u = 2.7 Gm = 13,000 umhos, Pd = 30 W/sect.

6528 u = 9.0 Gm = 37,000 umhos, Pd = 30 W/sect

I don't know that transconductance has any relationship to sound.

In this case, rnros has 6336 and 6528, both manufactured at the about the same time and in the same factory. And in my experience, this is more important than transconductance, gain or any other measurement....

I have to agree with gibosi here, I think the SQ characteristics, that we would typically discuss, are more the result of the construction/design than the performance specs of gain and transconductance. The accuracy, or sonic characteristics, of the signal amplification always seem to have some relationship to the construction/design, brand, factory, etc. At least those sonic characteristics we judge by ear, rather than by instrument.

There are many tubes with the same gain and transconductance that have very different sound characteristics. And there are tubes from the same production run with variances in transconductance that still show the same sound characteristics. Also as the tube ages, or the operating points are changed, etc. True we are talking about a larger magnitude of variance with the 6528 vs the 6336, but the sonic characteristics are more similar than different, at least on my setup. Yes, there are some differences but not as great as I expected, and I suspect it will vary for different rigs and headphones.

 

[JazzVinyl]

The quietest 12AU7s are those 7316s.
Did you use a 12au7 to 6sn7 adapter?

12AU7 to 12SN7 adapter.

 

[2359glenn]

There are many 12AU7s that sound better and are quieter then 6SN7s.
I have a old preamp with 12AU7s they are labeled Harman Kardon made in Germany that sound fantastic.
BTW I used to work for Harman Kardon.

 

[UntilThen]

Six power sockets
C3g
6/12/25 driver switch
Lundahl with 42EC4/PY500 rectifier
Gold Point Stepped Attenuator

It is very hard not to like all of the different tubes and enjoy them when you have many and you have many great ones.

Have you tried four 6AS7 power tubes with your LCD 2 ?
If so, how did you like the impact compared to a pair of 6336B powers ?

Like you, I could live with just a couple of my favorite combos, but it is very nice to be able to hear something a little different at times.

I may have to buy a few of the Svetlana 6H13C power tubes to lay around with...the price is right.

When I first started listening to headphones, I really liked the top end of the spectrum the most..it provides so much detail.
I have come to like the warmer sound as the years pass and I tend to love the bottom end of the spectrum more than ever before.
I like the bottom end of the warmer sound a lot now, as it seems to blend in seamlessly with a lot of my blues music. Glenns OTL is so transparent to tube rolling
and the bass it provides has impact and detail

It is hard to not go down the tube rabbit hole if you own one of Glenns OTL amps.

This amp is also great for people who are just getting into tubes. Glenn makes sure of that by making it use some very great sounding and cheaper tubes.
Heck if you want you can just grab six 6BL7/6BX7 and a pair of C3g and a rectifier of choice if needed and be done.
This combo will be a good as about anything you can buy tube wise for this amp, and will save a person "oodles" of cash.

My son and his girlfriend may just be living a couple of blocks away from us.
If this is the house they choose, then I know my wife will want to go over often. I can just take a pair of my headphones over and my son and I can both plug into his amp, pretty cool.

My son has the Senn HD650 and a Grado 225i.
I may grab a SE to 4 pin XLR adapter and I can use my HD800 when over there.

Good choice with that configuration. 6 x 6BX7 with a quiet combination is a very satisfying tone.

I've tried 4 x 6AS7 and 4 x 5998 but I find 2 x 6AS7 quieter and like most here, quiet is more important for me too. Both Cetron 6336b and Svetlana 6h13c sound very good on the OTL but my favourite is still Gec 6AS7G and Gec 6080. That is reserved for special occasions though. LCD-2f is quite easy to drive at 70 ohms. Even 2 x 6AS7 drives it well. However I might find 4 x 6as7 that is very quiet and I think I might prefer it. 4 does have a greater impact. That's why I've 4 Svetlana 6h13c on the way.

I've the best part of yesterday going through my headphones with ECC31 and 2 x Cetron 6336b. HD800, Eikon, Atticus and LCD-2f. I like them all. I find it hard to decide which 2 to cull from my collection. I might have to keep it all.

It is very hard not to like all of the different tubes and enjoy them when you have many and you have many great ones.

I agree wholeheartedly with this statement. You have a lot of tubes too and many good ones.