best use for some 26 tubes??

RE: best use for some 26 tubes??, posted on June 28, 2015 at 04:11:03
vinnie2 Audiophile Posts: 4481 Location: North Carolina Joined: September 28, 2013	Thanks Eli, most helpful. A line stage might be interesting at that.

Send them to Drummerwill., posted on June 28, 2015 at 07:09:11

drlowmu
Manufacturer

Posts: 9730
Location: East of Kansas City
Joined: January 10, 2005

His new Type 45 amp uses four, and he is low on 26s !!!

He is doing Version #2, so he needs 8 tubes for both stereo amps.

Jeff Medwin

http://db.audioasylum.com/mhtml/m.html?forum=set&n=78429&hig

Save them for keeping vintage radios alive, posted on June 28, 2015 at 10:36:57
Jim Doyle Audiophile Posts: 1180 Location: Medford, MA Joined: July 8, 2001	Best kept around so that in another 50 years, people will still be able to maintain those old radios from the 1920s. Let's stop using these vintage tubes for audio and stick to post WW-II stock!

Best Linestage Tube in Existence, IMO, posted on June 28, 2015 at 10:39:51

Maxamillion
Audiophile

Posts: 856
Location: New Jersey
Joined: May 26, 2006

Use Rod Coleman DC regulators on the filaments for a totally silent background. I also recommend battery grid bias through an input transformer, as shown in the schematic below. Here are a few pics of my 26 Linestage, which with the flick of a switch is also a tube output DAC using the Twisted Pear Buffalo III SE board and the same 26's as the output stage.

Picture of the Preamp/DAC internals:

Picture of the DAC Section Closeup with Sonore USB Interface Board:

Picture of the Power Supply Chassis Internals:

Sorry, they sound WAY too good, posted on June 28, 2015 at 11:04:31

Maxamillion
Audiophile

Posts: 856
Location: New Jersey
Joined: May 26, 2006

To waste in an old radio. See my post below.

Besides, soon enough over-the-air will be a dead medium, then the radios will really be useless.

RE: Best Linestage Tube in Existence, IMO, posted on June 28, 2015 at 11:52:46

Eli Duttman
Audiophile

Posts: 10455
Location: Monroe Township, NJ
Joined: March 31, 2000

The internal impedance of the "9" V. lithium battery you used is lower than that in an alkaline "equivalent". I satisfied myself of that fact, with a "Little Rat" phono preamp, years ago. A RAYOVAC 7 cell NiMH battery was even better, but can't be used in the grid circuit. The cathode current in a #26 would provide a quite adequate "trickle" to keep the NiMH pack fully charged. Can Mr. Coleman's filament regulator be set up "floating"? If so, the bias battery could be moved from the grid circuitry to the cathode circuitry.

Just my biases. I prefer to hold the number of caps. in the signal path, including ground legs, to a minimum.

Eli D.

RE: Best Linestage Tube in Existence, IMO, posted on June 28, 2015 at 12:09:39

Maxamillion
Audiophile

Posts: 856
Location: New Jersey
Joined: May 26, 2006

The cathode of the 26 is directly grounded. There is no cap in the grid circuit with this arrangement; the caps in the picture are a very small value film to bypass the battery for RF (optional) and the snubber cap for the transformer secondary to get nice square waves. The input transformer blocks the DC from the preceeding circuit, and also flips the polarity to counteract the flip from the SE 26 and steps down the voltage 2:1 to give a bit more headroom for the autoformer volume controls on the output.

Lots of ways to do it, of course.

RE: Best Linestage Tube in Existence, IMO, posted on June 28, 2015 at 12:43:12
Eli Duttman Audiophile Posts: 10455 Location: Monroe Township, NJ Joined: March 31, 2000	OK, the cap. across the bias battery is a RF bypass. I was wondering. The RC network across the I/P trafo suppresses ringing, among other things, and makes perfect sense. That's a BEAUTIFUL build, but way too costly for my circumstances. Eli D.

Coleman Regs can float, BTW, posted on June 28, 2015 at 12:52:43
Maxamillion Audiophile Posts: 856 Location: New Jersey Joined: May 26, 2006	to answer your question. I float them up to 250VDC in my 833C amps, pumping 10A of filament current through them. Very reliable and very quiet. Eli, you're in NJ too, right? I'm in Branchburg. Maybe you could stop by for a listen some time. Let me know via pm if you're interested.

RE: Send them to Drummerwill., posted on June 28, 2015 at 14:23:29
vinnie2 Audiophile Posts: 4481 Location: North Carolina Joined: September 28, 2013	That is an intersting looking amp. I love 45's so I may have to bread board it and give it a listen.

RE: Best Linestage Tube in Existence, IMO, posted on June 28, 2015 at 14:28:49
vinnie2 Audiophile Posts: 4481 Location: North Carolina Joined: September 28, 2013	I agree with Eli, a beautiful build, but out of my league price wise. You have me interested in trying to find something I could try tht would be a little less work and afew less bucks.

Here's the Thread for You, Vinnie, posted on June 28, 2015 at 16:21:15

Maxamillion
Audiophile

Posts: 856
Location: New Jersey
Joined: May 26, 2006

If you want to know all about 26 preamps. Looong, but packed with builds ranging from simple and cheap to complex and extravagant. Well worth the read.

http://www.diyaudio.com/forums/tubes-valves/151421-26-pre-am

RE: Best Linestage Tube in Existence, IMO, posted on June 28, 2015 at 16:36:04

Eli Duttman
Audiophile

Posts: 10455
Location: Monroe Township, NJ
Joined: March 31, 2000

I'll give you a hint for a low cost "300" V. B+ PSU that's vacuum rectified. ;>) "Full wave" voltage double the O/P of a Triad N-68X isolation trafo with a 117Z6. The N-68X easily has the "stones" to energize the rectifier's heater, along with the B+. Plenty of B+ current for a preamp.

Given today's higher average line voltages, put a 33 Ω resistor in series with each of the 117Z6's heater connections.

BTW, the Triad N-68X has dual primaries, which makes the setup described above "universal".

Eli D.

117Z6 Data Sheet

RE: Send them to Drummerwill., posted on June 28, 2015 at 17:34:13
drlowmu Manufacturer Posts: 9730 Location: East of Kansas City Joined: January 10, 2005	Never bread board an amp, build it in a final chassis, properly, and you will have something !!

RE: Send them to Drummerwill., posted on June 28, 2015 at 18:06:01
vinnie2 Audiophile Posts: 4481 Location: North Carolina Joined: September 28, 2013	That is something we will never agree on. I have breadboarded literally dozens of different designs of diy tube gear and will continue to do so. It is a quick, easy, cheap way to find out if you are interested in persuing a given design. Besides, it's just plan fun! : )

RE: Here's the Thread for You, Vinnie, posted on June 28, 2015 at 18:09:53
vinnie2 Audiophile Posts: 4481 Location: North Carolina Joined: September 28, 2013	Looks like I will have to work my way through this one. Thanks!

RE: Best Linestage Tube in Existence, IMO, posted on June 28, 2015 at 18:11:21
vinnie2 Audiophile Posts: 4481 Location: North Carolina Joined: September 28, 2013	I am afraid I would need a schem to put together something like that Eli; it's a bit over my head. Thanks for the thought though.

The Type 26 in an all DHT 3 stage amp...., posted on June 28, 2015 at 21:25:29

drummerwill
Audiophile

Posts: 965
Location: St Louis Mo.
Joined: January 7, 2003

This is what I settled with instead of going a more expensive way of the 2 Stage all DHT amp.

Until you've heard an all DHT amp, this may mean nothing to you if you don't have Hi-Efficiency speakers.

The ultimate for me would have been a 2 stage all DHT amp. but the expense of a quality Input tube ( EML 30A or 20A whatever) was beyond my means.

So I just use 2 lower gain cheaper Type 26 tubes.....

I'm Happily assembling a second Version of the 26-26 DC 45 amp.

And Vinnie I'd like to contact you about acquiring a few of those 26's...

Willie

RE: The Type 26 in an all DHT 3 stage amp...., posted on June 29, 2015 at 04:48:58
Al Noakes	You should be able to use the thoriated tungsten filament 3C24 which makes an excellent driver . Mu is 20 Ra 15k . I did an amps using 3C24 driving PX4 which I though sounded very good Al

RE: The Type 26 in an all DHT 3 stage amp...., posted on June 29, 2015 at 04:59:11
vinnie2 Audiophile Posts: 4481 Location: North Carolina Joined: September 28, 2013	Send me an email and we can discuss it.

RE: The Type 26 in an all DHT 3 stage amp...., posted on June 29, 2015 at 12:12:26
vinnie2 Audiophile Posts: 4481 Location: North Carolina Joined: September 28, 2013	Your email address is no working Wille. You need to go into the asylum and correct it. Please send me another email when you have done so and I will answer your first email. Vince

Schematic, posted on June 29, 2015 at 16:30:58
Eli Duttman Audiophile Posts: 10455 Location: Monroe Township, NJ Joined: March 31, 2000	You asked for it. :>)) Eli D.

RE: Schematic, posted on June 29, 2015 at 17:44:54
vinnie2 Audiophile Posts: 4481 Location: North Carolina Joined: September 28, 2013	Thanks Eli. Most interesting.

Tube DIY Asylum

best use for some 26 tubes??

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