[Isaacc7]

Have you used 6AT6 or 12AT6? I looked in several datasheets and some mention 1W, other 0.5W for plate dissipation. 1W is fine, if I keep them at 3mA. But for 0.5W I am quite at the limit. Not sure if to proceed or not. I can go towards 2.5mA (0.0025 x 180 = 0.45W). Maybe I understand something wrong.

I have never used them. I get in enough trouble with my own tube wandering, stop tempting me with another path to go down

 

[OctavianH]

I have never used them. I get in enough trouble with my own tube wandering, stop tempting me with another path to go down

Well, Tomas was very careful keeping 6SL7 at 3mA with Pd = 1W. I am thinking if I should try these close to their maximum limit, but I guess all can happen is that the tube dies. No damage to the amplifier.

 

[triod750]

I guess all can happen is that the tube dies.

..or Heaven can fall down on you? Beware!

 

[OctavianH]

Well, this is a double-diode triode. So most probably the rating is made when all are used. Since in my case I'll need only the triode it should be fine. I am curious on Oblivion what operating point they had.

 

[Isaacc7]

As much as I have enjoyed the c3m and vt60a combo, there are more tubes to get to! They aren’t going to listen to themselves….

So I added that combo to my list of favorites and it’s time to get back to the 6bg6 experiment. I loved the RCA 6bg6ga with the GEC b36 brown base but not so much with the c3m. I am not patient enough to wait the 20 minutes or so that is recommended to allow the c3m to cool down so I kept them in and switched over to the GE 6bg6ga. These are the ones with the large plates that look very much like the GE 6l6gc.

My initial impressions are positive, better than the RCA/c3m combo at least. As I head into my 2nd hour I’ve realized that this sounds very similar to the results I have gotten using the KTZ41 inputs. Big, indistinct, and vaguely warm. The bass is looser than the vt60a but that is one of its strong suits. Will allow these tubes to settle in over the next couple of nights and see what happens. Since I didn’t like the c3m with other 6bg6 tubes I’m inclined to try some others but will resist for now.

 

[OctavianH]

While you advanced with rolling I made a step back and started to refresh a little bit my know-how. A very important thing we are usually ignoring is to check all our adapters and see exactly how they are connected. I made this for several relevant types, and in combination with some pinout study I realized a lot of very important things. For example that I can reuse a lot of them, in specific cases. I strongly advise any of us doing what I do to step back and investigate in this area for a while. I also discovered a lot of tube types, using some "Philips Pocket manual" which helps finding equivalents, which can be very interesting to try, some of them in existing adapters. Now I only need some planning and of course, filtering to find the real gems. I checked also the datasheets of 6AT6/6AV6/EBC90/DH77/CV452 to see a little bit what the situation. We will see where this goes. A certainty is that EL85 is close, as a normal successor to EL42 rolling phase. I also plan to make an unconventional test with EL85 in another adapter, because I am 99% will work. But about that later, to avoid giving wrong advice to anyone. Remember, rolling is not properly made until you do not understand pinouts and adapters and stuff.

Later edit:
I guess I'll also try EL36, would be interesting since I checked the datasheet recently. Has to work with Vg around -40V. If 12E1 worked, EL36 works for sure.

 

[Isaacc7]

While you advanced with rolling I made a step back and started to refresh a little bit my know-how. A very important thing we are usually ignoring is to check all our adapters and see exactly how they are connected. I made this for several relevant types, and in combination with some pinout study I realized a lot of very important things. For example that I can reuse a lot of them, in specific cases. I strongly advise any of us doing what I do to step back and investigate in this area for a while. I also discovered a lot of tube types, using some "Philips Pocket manual" which helps finding equivalents, which can be very interesting to try, some of them in existing adapters. Now I only need some planning and of course, filtering to find the real gems. I checked also the datasheets of 6AT6/6AV6/EBC90/DH77/CV452 to see a little bit what the situation. We will see where this goes. A certainty is that EL85 is close, as a normal successor to EL42 rolling phase. I also plan to make an unconventional test with EL85 in another adapter, because I am 99% will work. But about that later, to avoid giving wrong advice to anyone. Remember, rolling is not properly made until you do not understand pinouts and adapters and stuff.

Later edit:
I guess I'll also try EL36, would be interesting since I checked the datasheet recently. Has to work with Vg around -40V. If 12E1 worked, EL36 works for sure.

Oh how I wish there was an easy way to search tubes by pin outs. We’re using tubes in ways that were never anticipated. I can imagine requesting that to the people writing the tube manuals, “What? Why would anyone want that?” Lol

 

[OctavianH]

There are a lot of tricks to make with adapters. Especially if you have both stages wired so similar like 6V6 and 6J5. I mean except G2 are similar.

And I also have 3+6 and 4+5 to use 6N7. On output I have 1+8 to be able to use EL34.

Now, an adapter made towards 6J5 for a triode I guess has to work also on output. The problem is that the triode needs to work at 20mA. Basically pins are 1:1 except screen grid. An adapter for a pentode for example, has usually G3 + Cathode (grounded) and G2 via 100 Ohm to Plate. So you strap in the adapter not socket, but I guess might work. There are a lot of things you start to see after you make connection tables for the adapters (to see what is grounded, floating, what is internally connected and you do not care, eventually measure resistance between that pin and others just to see if might have any effect).

What to say, I made myself a big XLS with pinouts, and a big XLS with adapter connection and saw some stuff. I will, of course, experiment on my tube tester, I can connect and replicate my socket connection, then put those adapters with tubes and see if my tube raises current or not. So if I am totally crazy or not.

Anyway, real rolling starts when you take a look on a big screen on all these connections. I advise anyone to try this.

PS. Found also some differences on pinouts from The Valve Museum and some old datasheets. I will check both from now on. The website was easier.

 

[OctavianH]

Treating myself with some Tung Sol 6SL7 and Mullard EL32. Simple and nice.

Tung Sol is a very honest brand and counters quite good that veil smooth sound of the Mullard. Mullard is wrong from so many points of view, but still we sometimes like it.
My current preferences? The drawer never lies.

Simple as that, put many to rest in the storage. Mostly what all praise on other amps. LOL

 

[OctavianH]

I've just received my adapters for 6AV6/6AT7 -> 6J5 and EL85 ->6V6 from Deyan. The new ones, aluminium. Look quite cool, heavy, and it's interesting that he uses housing with different thickness based on the needed socket for these. Cool stuff.

 

[OctavianH]

Combo of the day: Mullard ECC33 with Telefunken EL803. EL83 is a kind of EL84 (soundwise, not pinout), same energy and gain but here you get the Telefunken flavour. Warmed a bit with Mullard ECC33 gives you a really top class sound.

But you should not buy an ECC33, a simple ECC40 sounds quite nice with these and has around the same gain. For example my Sittard made one is also excellent.

 

[OctavianH]

Going down with the gain today. Sylvania "green leaf" 76 with GEC ATS25. Volume knob around 2AM.

Nice sound from these, Sylvania was always airy for me, brings some good space to the rich outputs.

 

[Isaacc7]

I have been having difficulty getting a sound I like from the GE 6bg6ga, just like in the other amp. The C3m inputs were a bit flat sounding, the bl63 rounded everything off both top and bottom, and the GEC brown base b36 while much clearer seems to have lost the bass.

It occurs to me that since the plates of the GEs look so much like their 6l6gc maybe I should run them as that instead of the 807 settings I’ve been using. Instead of 320v 40ma I will try 350v 70ma. Triode 807 can be used at 400v and the 6l6gc can take quite a bit more juice so I’m not afraid of frying the tubes.

 

[Isaacc7]

Switching to UL has totally transformed the GE 6bg6ga. Now, with the BGRP 12sn7 they are open and clear with a great balance across the frequency range. Trying to figure out the best operating points for a 6l6gc was just confusing so I‘m back to my normal 320v 40ma settings. Will settle in with this combo through Wednesday probably.

 

[OctavianH]

Switching to UL has totally transformed the GE 6bg6ga.

TR/UL is something interesting I would like to try.

By the way you said you buy some headphones to try on your Odyssey? What have you chosen?