[UntilThen]

Roger that!

Everything noted down. Might consider the Gold Point attenuator when ordering. I'm leaning towards this OTL config:
- Lundahl transformer
- 6 output sockets
- C3g sockets
- 6/12/24 volts switch
- RCA pre-out
- HEXFRED rectifier
- Probably the stepped attenuator

I don't have planars in my stable and don't plan in the near future so no bias switch for the 5998 (or lower impandance for the 6336s).

Good choice with that OTL configuration.... except if my EL11s develops further and I like it for the long run, I might send it back to Glenn to get the c3g sockets replaced with EL11's.

This OTL amp will drive a planar headphone without breaking a sweat. Drives my LCD-2f with absolute ease and I'm using EL11s with 6 x 6bx7gt. I also have both hd800 and lcd-2f plug in now together and the amp has enough power and control to drive both simultaneously.

I'm not using the 5998 boost switch. It's there. It's nice to have but I am not using it.

 

[Oskari]

There was a lot of cross branding. I found an unusual looking tubular EL3N for sale by Billings in England. After a lot of back and forth I was able to identify it as a real Telefunken tube. (Didn't buy it {yet})

Like their tubular EL11? Must be pretty rare.

 

[mordy]

Been digging in the bargain bins lately - I love inexpensive good tubes!
I have acquired 5 6C8G tubes with the average price under $8 shipped.
I am biased towards older tubes, but cannot date these two tubes:

The left tube is an older Sylvania with the green leaf and a code that reads T 3(?). Haven't been able to date it - does anybody know?
The right tube is a RCA. It has much more information on it. Joint Army & Navy CRC, SC71 (Signal Corps inspector #71?) and date code O-43.
Don't know how to date it or even if it was made by RCA. 43rd week 1950? Secret Operations 1943? Anybody?
Of the five tubes the National Union and above two tubes sound the best.
These tubes (and 6F8G) really sound very good and could be great and inexpensive 6SN7/6SL7 substitutes (but need a special adapter).

 

[mordy]

Like their tubular EL11? Must be pretty rare.

Yes - tubular.
Did not buy because I have a lot of EL3N tubes and I cannot use them right now in my GOTL until I find a suitable adapter that doesn't exist yet (EL3 to C3g).
But you are right, they must be very rare. I didn't believe that TFK made them, but I asked them to turn the actual tube upside down and look for two letters next to the pins. They were there, and I think I remember a 1944 date.
Found the UK eBay offering but I don't know if they still are available.
https://www.ebay.com/itm/112568484520?ul_noapp=true

Test your Swedish: What does Ror mean?

 

[Oskari]

In the past I tried out several different EL11 tubes from various manufacturers. The Adzam is Mazda backwards. If I am correct Mazda was an independent company (Trivia: There was a time when light bulbs were called mazdas) that later became part of Philips.

Adzam was the tube brand of MBLE, a Belgian manufacturer.

Mazda was originally a GE light bulb brand. They had subsidiaries and licensees in various markets. That's why the name Mazda appears here and there, also in Belgium for MBLE's light bulbs.

Yes, MBLE (aka Adzam aka Belgian Mazda) was in Philips's camp.

 

[Oskari]

Test your Swedish: What does Ror mean?

Thanks, Mordy. I'll leave the test for others.

 

[mordy]

Thanks, Mordy. I'll leave the test for others.

The word means valve, valvola, rohre or tube, but ror is Swedish - don't know if these TFK tubes originally were destined for Sweden or bought there.
Any ideas about the dates on my 6C8G tubes?

 

[Oskari]

Any ideas about the dates on my 6C8G tubes?

Getting there… if my browser would stop freezing.

 

[Oskari]

The right tube is a RCA. It has much more information on it. Joint Army & Navy CRC, SC71 (Signal Corps inspector #71?) and date code O-43.
Don't know how to date it or even if it was made by RCA. 43rd week 1950?

That should be correct. CRC = RCA.

Sylvania T3: According to Sibley (Tube Lore), guarantee ends Beginning of 1944, shipment interval Nov 1942—Jan 1943.

 

[mordy]

That should be correct. CRC = RCA.

Sylvania T3: According to Sibley (Tube Lore), guarantee ends Beginning of 1944, shipment interval Nov 1942—Jan 1943.

Thanks. If the Sylvania is for civilian use, why does it not say M-R? (Maybe worn off?)
Any luck with the RCA O-43 code?

 

[leftside]

I know you guys like GEC tubes, tube amps and adapters, so thought I'd post a few pics of my amps with GEC TT21s with adapters. I like these tubes just as much, if not more so than the GEC KT88s.

Steampunk amps.

 

[Oskari]

Thanks. If the Sylvania is for civilian use, why does it not say M-R? (Maybe worn off?)
Any luck with the RCA O-43 code?

1. Don't know.
2. I meant that what I quoted was all correct.

 

[mordy]

1. Don't know.
2. I meant that what I quoted was all correct.

Thanks for your information.
Re warranty - I have a 1942 RCA 6F8G tube that has printed on the box "Guaranteed for 50 hours."

 

[mordy]

I know you guys like GEC tubes, tube amps and adapters, so thought I'd post a few pics of my amps with GEC TT21s with adapters. I like these tubes just as much, if not more so than the GEC KT88s.


Steampunk amps.

Hi leftside,
Stunning display - I can only imagine how it sounds!
Maybe an idea for a spare GEC TT21?
https://www.ebay.com/itm/1x-TT21-GE...h=item2abac9886c:g:rhwAAOSwfONb4cgv:rk:1:pf:0

 

[leftside]

I imagine that TT21 will sell for a lot higher. I got my TT21s this week from Billington in the UK. Made quite a few purchases from them this year... Ordered the TT21 to KT88 adapters last weekend from our friends in China. Usually it takes about 6 weeks for goods to arrive from there to Canada. Amazed (and very happy) these only took a week. Work great.