Search found 35 matches

by DowdyLama
Sat Dec 12, 2009 7:37 pm
Forum: Transformers
Topic: IT for 826
Replies: 13
Views: 18779

follow-up

I realize this is an old thread, but I wanted to post more recent experience with the 826: I'd like to amend what I said earlier, the 826 sounds every bit as good as the 3C24/25T ('tho I would not say it sounds better). The 826 does indeed need at least 500 vpk to begin to shine...and the lack of a ...
by DowdyLama
Mon Dec 07, 2009 6:06 pm
Forum: Current Cancellation
Topic: a 1:1 nickel IT for a 10
Replies: 20
Views: 22694

I should've known that I was missing part of the story...maybe one day I'll have a life again :cry:

In any case, two-stage A2 is pretty difficult to pull off in my estimation...and while I'm being a cynic: won't a bifilar have problems with grid current?

Jim
by DowdyLama
Sun Dec 06, 2009 11:22 pm
Forum: Current Cancellation
Topic: a 1:1 nickel IT for a 10
Replies: 20
Views: 22694

In my estimation, A2 is out of the question here. Heck, if you want A2, I'd say you're better off to start from scratch with a tube designed for A2. You know, the 826 would make a dandy A2 output device with no dangerous plate caps to worry about. Re: metal-plate 211s: yep, I've thought about it, bu...
by DowdyLama
Sun Dec 06, 2009 8:48 pm
Forum: Current Cancellation
Topic: a 1:1 nickel IT for a 10
Replies: 20
Views: 22694

Buzz: Aside from asking that you not produce it commercially, you may feel free to use the 826. It's an excellent driver, but be forewarned that its filament draws a LOT of current! The 3C24 sounds virtually identical to the 826, and will save you about 20% on filament current. Of course, the mu is ...
by DowdyLama
Sun Dec 06, 2009 3:48 pm
Forum: Current Cancellation
Topic: a 1:1 nickel IT for a 10
Replies: 20
Views: 22694

Guys:

I don't know off the top of my head exactly what a Hammond 715 is, but I'm guessing that you're exceeding the 83's voltage ratings.
Is a mu of 8 (or 5.6 with the 46) adequate? Buzz, don't tell me you're falling for Jeffrey's "we don't need no stinking gain" mantra :wink:

Jim
by DowdyLama
Thu Nov 19, 2009 4:49 pm
Forum: Transformers
Topic: Inverting Interstage Transformers.
Replies: 5
Views: 7552

Cool stuff - way to go Dave!

Jim
by DowdyLama
Wed Feb 18, 2009 4:37 pm
Forum: Phono
Topic: 416C defined source Z phono
Replies: 7
Views: 9165

I played with the 416s last year.
I could get them to bias, but could never get them to sound good...had to install 3k3 grid stoppers to avoid unprovoked oscillation - I finally gave up on them.

Please keep us informed - I'd love to figure out how to make music with them :?

Jim
by DowdyLama
Sun Dec 21, 2008 9:19 pm
Forum: Current Cancellation
Topic: new project, new challenges -> CC IT for 100TH driving GM
Replies: 17
Views: 19537

Or, you can do like I do: use an existing DC filament supply/variac, and...this is the important part: decide what a *convenient* B+ would be and start with that 8)
Then clip in a 1k cathode resistor and see which direction you need to go in re: bias.
by DowdyLama
Fri Dec 19, 2008 5:17 pm
Forum: Phono
Topic: Transformer phono correction
Replies: 54
Views: 45341

This is pretty fascinating - thanks for the post Pete!

I'd be very interested in experimenting with this approach...especially involving some of the tubes I really like 8)
by DowdyLama
Fri Nov 07, 2008 3:45 pm
Forum: Phono
Topic: Where to squeeze a 600ohm LCR riaa network
Replies: 4
Views: 5321

Yeah - I think it's an interesting approach - keep us posted!
by DowdyLama
Mon Aug 25, 2008 3:46 pm
Forum: Inductors
Topic: lowmu hihenry
Replies: 3
Views: 6031

I'm using the 826 as V1 in a 2-stage SE GM70 amp; it's pretty much my standard GM70 amp, just replacing the 3C24 with an 826. This is the amp that Jonathan Weiss will be demoing in his NYC loft, and I didn't want plate caps to scare anyone away ;-) P.S. I'm unaware of a rectifier shaped like the 826...
by DowdyLama
Sun Aug 24, 2008 8:20 pm
Forum: Inductors
Topic: lowmu hihenry
Replies: 3
Views: 6031

I picked these up in trade from Low Mu and have put them to work on an 826 - about 500 vpk @ 10 mA [the light green line on the above chart]...working great!
by DowdyLama
Tue Jan 29, 2008 5:30 pm
Forum: Transformers
Topic: Proposed interstage coupling transfo
Replies: 4
Views: 5405

Only 65k?
:shock:
by DowdyLama
Sat Jan 05, 2008 3:47 pm
Forum: Current Cancellation
Topic: big SE
Replies: 2
Views: 6461

You da man, Doug!
by DowdyLama
Mon Sep 24, 2007 1:14 pm
Forum: Attenuators
Topic: Sowter TVC mystery
Replies: 3
Views: 4611

I did ground the secondary (which eliminated that last bit of hum I was tracking down), but I still don't understand why it was working at all!
by DowdyLama
Mon Sep 17, 2007 7:52 pm
Forum: Attenuators
Topic: Sowter TVC mystery
Replies: 3
Views: 4611

Sowter TVC mystery

I am rebuilding a linestage for a customer utilizing a Sowter TVC at the input - someone else did all of the original wiring; I am simply replacing the original 6AH4 with a filamentary-bised 71A. In tracking down some minor hum, I discovered that the ground on the TVC secondaries is ungrounded...whi...
by DowdyLama
Sat Sep 01, 2007 11:11 pm
Forum: sbench 101
Topic: 45 Watts per channel push pull 801As
Replies: 15
Views: 24021

Yes - uber-cool stuff!
by DowdyLama
Fri Feb 02, 2007 11:29 pm
Forum: Transformers
Topic: SE amps to drive ES panels.
Replies: 20
Views: 26323

This is totally unrelated to tubes or transformers...it's purely nostalgic. I lived in Kansas City from 1978 through 1981 - during that time I recall a listening session at someone's house who had Stax ES speakers driven by a large pair of Stax SS amps [my young ears thought they sounded pretty good...
by DowdyLama
Sun Jan 21, 2007 7:42 pm
Forum: Transformers
Topic: IT for 826
Replies: 13
Views: 18779

More re: 3C24/25T: > What do you think about more juice, like 750 v, 20 mA No opinion; but I certainly encourage experimentation - heck, the 826 might sound great with 750 vdc! > Why not use 200H? My general rule of thumb is not less than 30 Hy per 1k of R(p)...I also used the plate chokes that were...
by DowdyLama
Thu Jan 18, 2007 6:58 pm
Forum: Transformers
Topic: IT for 826
Replies: 13
Views: 18779

I personally prefer the sonics of the 3C24/25T vs the 826; plus, in my experience, the 3C24/25Ts tend to have less problems with gassiness. Please note that I've never experimented with any of these tubes above 450 vdc - it's possible that the 826 would really shine with 500 to 600 volts on the plat...
by DowdyLama
Wed Jan 17, 2007 3:08 pm
Forum: Transformers
Topic: IT for 826
Replies: 13
Views: 18779

826s do tend to be gassy - I can only speculate that it's the early Septar basing combined with brittle pins and glass.

They sound pretty good, but not quite as good as the 3C24/25T to my ears.

FWIW: I've never run any of these tubes much higher than 450 vdc.
by DowdyLama
Wed Jul 12, 2006 4:51 am
Forum: Your name here.
Topic: dowdy LCL
Replies: 2
Views: 5347

Thanks Dave - V1 was a 6J5 here - R(p) of approx 6k.
by DowdyLama
Thu Jul 06, 2006 8:41 pm
Forum: Phono
Topic: LCR riaa's
Replies: 96
Views: 117232

"The tradeoff becomes the tube sonics and the difference between an 8:1 with a 10+X source ot load ratio and a 1:1 with a 3X ratio...but the 1:1 is much more appealing from the iron viewpoint." Absolutely - and that's my whole point! I'm going to continue to consider the monkeyed 6C45-6AS7...
by DowdyLama
Tue Jul 04, 2006 10:19 pm
Forum: Phono
Topic: LCR riaa's
Replies: 96
Views: 117232

"thinking of the 421A are we?" I'm certainly thinking of using either the 421A and/or the 6AS7 into a 1:1 here - my extremely generalized experience [whether considering the output z of a linestage or an A2 driver] has been that we often pursue (the theoretical notion) of low impedance at ...
by DowdyLama
Tue Jul 04, 2006 5:06 am
Forum: Phono
Topic: LCR riaa's
Replies: 96
Views: 117232

Assuming that we're sticking with the 600 ohm units for now [with a 600 R termination]:
how does it look with source = 1/2 load? or even
source = 1/3 load?
by DowdyLama
Fri Feb 24, 2006 10:22 pm
Forum: Resistors
Topic: What about different cores for better cooling?
Replies: 4
Views: 8775

> Are you still running these bypassed Jim? All of what I wrote involved cathode resistors that were bypassed - although one of the set-ups was only 90% bypassed [75TH drawing 24 mA]. > if they impart a clarity to the amp through the lack of noise There's definitely an increase in clarity - it's one...
by DowdyLama
Wed Feb 22, 2006 5:34 pm
Forum: Resistors
Topic: What about different cores for better cooling?
Replies: 4
Views: 8775

quasi-scientific hypothesis

> When it comes down to it, these things do not heat that much. Dr. Dave is correct, but, FWIW: I'm beginning to suspect that his uber-cool cathode resistors perform best drawing smallish amounts of current. Again, I'm merely proposing a quasi-scientific hypothesis here. I've only compared in the ca...
by DowdyLama
Wed Mar 23, 2005 6:05 pm
Forum: Resistors
Topic: R(k) listening report
Replies: 13
Views: 16880

more

The 260 ohm [nominal] resistors have been installed. Excellent sonic results once again, quite similar to previous experiments. The L-cancelling mode still sounded best, however the difference between L-cancelling and non-L-cancelling was much less than with the 910 ohm resistors. Dr. Dave assures m...
by DowdyLama
Sun Mar 20, 2005 1:31 pm
Forum: Inductors
Topic: 75 TL chokes
Replies: 2
Views: 5643

thanks, Dave!

Tubes in question are actually 75THs, drawing about 21 mA in the current set-up.
by DowdyLama
Fri Feb 04, 2005 5:09 pm
Forum: Resistors
Topic: R(k) listening report
Replies: 13
Views: 16880

Gosh Dave, I really don't know what the temperature will be. So your best guess will be good enough for me.

How much variance will there be? Meaning, if the resistor is 260 ohms at 90 degrees F, what will it be at 120 degrees F? [Or vice-versa?]