[Deyan]

Takes around 2 weeks to the US.

 

[bcowen]

'Tis the season to be ... fiddling about.

I finally got a round tuit, and asked @Deyan to fabricate my favorite fantasy tube adapter for Mjolnir2: 6SN7 to 6922, with a separate umbilical just for the filaments. Filumbilicus?

No idea how long shipping might take at this time of year. I went series connected, just to control the overall current draw, but parallel filaments should work fine, too.

At least initially, I'll be using a simple Korad linear bench supply for the 12.6 volt series string, in constant current mode for 600 mA.

I measured my un-matched Footscray CV1988's last night with my Fluke, and the cold filaments are about 2.3/2.4 ohms, needing over 2.5 amps at 6.3 volts.

I theorized the Korad would reduce the voltage to ~1.5 volts and then raise it as the filaments reached operating temperature.

This morning, I lit each tube individually and everything behaved as expected, taking some 30 seconds to stabilize, a nice soft start.

Deyan's adapter will be usable with MJ2, VH2, even Lyr3 with a jumper in the 2nd socket, and put 6SN7, 8SN7, 12SN7 or anything adaptable to ?SN7 within reach.

Oh boy Oh boy Oh boy

You are creating an entirely new dimension of tube rolling. I hate you.

 

[G0rt]

You are creating an entirely new dimension of tube rolling. I hate you.

I'm surprised nobody's yet tried it, at least in public, at least with Schiit.

Grounding as always is a potential hairball, but there are ways and means. Won't know until I know.

 

[G0rt]

I don't always measure current, but when I do...

 

[jonathan c]

I don't always measure current, but when I do...

…I have a Dos Esquis in hand……

 

[G0rt]

…I have a Dos Esquis in hand……

I haven't had a drink all day. I'll fix that now.

I played with 3 pairs of tubes today, just lighting them up in series & observing filament current at different voltages.

A pair of CV1988 Footscrays (a '52 KB/N & a '54 KB/FB) draw 605 mils @ 12.6 VDC, or 600 @ 12.4.

A pair of NOS Westinghouse 6SN7GTB's pull less than 600 mils even @13.1 VDC.

A pair of NOS American Tung Sol 6SN7GTB's pull 600 mils @ 12.9 VDC.

The drops across the Brimars were within 85 mV of each other, so close enough for govt work.

+-5% of 12.6 gives 11.97 to 13.23 V as a sensible range, with 600 mils the soft target.

I'm guessing the GTB's behave the way they do due to their controlled warmup design. I've got some GTA's around here somewhere...

 

[bcowen]

…I have a Dos Esquis in hand……

LOL!

I was gonna say those were the most interesting measurements in the world, but you beat me to it.

 

[Guidostrunk]

LOL!

I was gonna say those were the most interesting measurements in the world, but you beat me to it.

 

[billerb1]

Long time, no see. Hope all of you are happy and well. Thought I'd pass this along even though (as usual) it's not on topic. I just finished replacing pretty much all my cabling (headphone cable, interconnects, coax and power cords) with ones from a small shop in Colorado called Audio Envy. Do some research if you find yourself thinking about upgrades in this area. You'll find that their reputation is that they swing WAY above their weight. If you are anything like me and can't afford thousands of dollars on cables, these really deliver incredible bang for the buck. Such a change for the better with my rig. The music spigot is wide open.
Have a great holiday season guys !!!

 

[jonathan c]

Long time, no see. Hope all of you are happy and well. Thought I'd pass this along even though (as usual) it's not on topic. I just finished replacing pretty much all my cabling (headphone cable, interconnects, coax and power cords) with ones from a small shop in Colorado called Audio Envy. Do some research if you find yourself thinking about upgrades in this area. You'll find that their reputation is that they swing WAY above their weight. If you are anything like me and can't afford thousands of dollars on cables, these really deliver incredible bang for the buck. Such a change for the better with my rig. The music spigot is wide open.
Have a great holiday season guys !!!

A fascinating outfit…

 

[billerb1]

Been going thru all my front line tubes with my now burned-in new interconnects and cables...alternating between Brimar 455's, Brimar Square Getters, Telefunken ECC801S's and RFT ECC81's. They are ALL such quality tubes and certain songs bring out the most desireable qualities in each tube. The biggest 'surprise' so far to me has been the somewhat forgotten Brimar Square Getters. I'm finding myself drawn to that somewhat more upfront presentation they have, especially with the vocals. Had forgotten how intimate and engaging those vocals and certain instrumental solos could be with the Squares. Anyway, it's so great to have choices...and it's hard to go wrong with any of these.

 

[Wes S]

Been going thru all my front line tubes with by now burned-in new interconnects and cables...alternating between Brimar 455's, Brimar Square Getters, Telefunken ECC801S's and RFT ECC81's. They are ALL such quality tubes and certain songs bring out the most desireable qualities in each tube. The biggest 'surprise' so far to me has been the somewhat forgotten Brimar Square Getters. I'm finding myself drawn to that somewhat more upfront presentation they have, especially with the vocals. Had forgotten how intimate and engaging those vocals and certain instrumental solos could be with the Squares. Anyway, it's so great to have choices...and it's hard to go wrong with any of these.

Good stuff! I have been digging those old Brimar ECC82 Square Getters as well! I pulled one out of my stash the other day that I got from @TK16 a couple of years ago, and to my surprise it's been a killer tube in my Pendant, with a very immersive and holographic stage and vocals to die for. Long live Footscray Brimars!

 

[billerb1]

Good stuff! I have been digging those old Brimar ECC82 Square Getters as well! I pulled one out of my stash the other day that I got from @TK16 a couple of years ago, and to my surprise it's been a killer tube in my Pendant, with a very immersive and holographic stage and vocals to die for. Long live Footscray Brimars!

These are the 1957 Brimar CV4033's Squares most of us got from Sanjiv which I'm pretty sure are ECC81's. It's an interesting comparison between the Brimar 455's that I got from Langrex and these 4033's from Sanjiv. The 455's extract a bit more detail but on my rig seem a few rows farther back and a tad less rich in texture/tone. The Teles are my favorites just for sheer tone, especially on acoustic...but they lack some of the soundstage nuance of the Brimars. The RFT's are good at everything but don't seem to have that one identifiable signature sound that puts them above the rest. Very detailed and very musical...but a bit thinner than either of the Brimars or Teles in resonance/timbre with my new setup.

 

[Wes S]

These are the 1957 Brimar CV4033's Squares most of us got from Sanjiv which I'm pretty sure are ECC81's. It's an interesting comparison between the Brimar 455's that I got from Langrex and these 4033's from Sanjiv. The 455's extract a bit more detail but on my rig seem a few rows farther back and a tad less rich in texture/tone. The Teles are my favorites just for sheer tone, especially on acoustic...but they lack some of the soundstage nuance of the Brimars. The RFT's are good at everything but don't seem to have that one identifiable signature sound that puts them above the rest. Very detailed and very musical...but a bit thinner than either of the Brimars or Teles in resonance/timbre with my new setup.

Oh got ya, those CV4033 square getters are good too. Also, I have started to notice the same thing with the RFT's as well, and I like Brimar's more organic house sound flavor a bit more too.

One of these days I am going to have to try out one of those Teles. . .

 

[billerb1]

Oh got ya, those CV4033 square getters are good too. Also, I have started to notice the same thing with the RFT's as well, and I like Brimar's more organic house sound flavor a bit more too.

One of these days I am going to have to try out one of those Teles. . .

I've never heard anyone say the Tele ECC801S's have a great synergy with the MJ2...but I feel like they do with my Woo WA2. You know how this game goes, Wes.