#26 pre amp - Page 118

Rod Coleman · 1st September 2011, 07:26 AM

Quote:

Originally Posted by andyjevans

Is that some sort of copper tape around the chokes? Details please!

Does this cut down on hum in chokes and the 26 tubes? What did you find?

Andy

I use this, too, to get electrostatic screening into tight corners.

Chomerics tape can make a reliably conductive joint - the adhesive is also conductive.

It's fiercely expensive,though:

CHOMERICS|CCH-18-301-0100|TAPE, ADHESIVE, COPPER, 25.4MM | Farnell United Kingdom

hihopes · 5th September 2011, 10:16 AM

Hey, does any kind soul have a couple of pairs of various decent 26's to spare? Or perhaps know of somewhere I can get them for a decent price? (Besides E-BAY. Been watching that for a while.).
I will be happy to pay for them (via Paypal). I really, really want to hear for myself this "magic" so many talk about. You can PM me if you'd rather not post on the forum.

hihopes · 5th September 2011, 10:23 AM

BTW, a lot of people have said they are not mad about the sound of LED biasing. I wasn't either, until I tried bypassing the LED string with quite large value low ESR caps. WOW! Different beast. It worked on IDHT's, and even better on 4P1L DHT's too. The new polymer caps are good for this. I used Oscon SEP's 330uF 16v. It seems the better the quality of the valve, the more you have to gain by doing this. I would love to hear the outcome if someone could try it on a 26 preamp or gainstage. You can also bypass the bypass caps with good foil caps for yet another step up in sound. Really worth a try IMHO.
Regards,
William.

merlin el mago · 5th September 2011, 11:09 AM

Quote:

Originally Posted by hihopes

Hey, does any kind soul have a couple of pairs of various decent 26's to spare? Or perhaps know of somewhere I can get them for a decent price? (Besides E-BAY. Been watching that for a while.).
I will be happy to pay for them (via Paypal). I really, really want to hear for myself this "magic" so many talk about. You can PM me if you'd rather not post on the forum.

andyjevans have some ST type for sale
FS: 6SN7 JAN black glass tubes + DHTs

andyjevans · 5th September 2011, 12:33 PM

I have a small number of 26 ST, but I'd also recommend 01A and 30 special. I have loads of those so interesting prices. Andy

FRUGIVO · 6th September 2011, 05:16 PM

inside the star #26

hihopes · 8th September 2011, 03:15 PM

I hope you didn't drop that on the floor, frugivo!

Has anyone tried loading the 26 plate by any other means than resistor or trafo/choke? (Sorry if it has been posted already, but I really can't face wading through all those posts again!)

Vinylsavor · 8th September 2011, 04:03 PM

Hi!

I guess the 26 has been loaded by just about everything possible: transformers, chokes, CCS, triodes and pentodes for SRPP, mu-follower, mu stage etc.

For me as preamp output only transformer coupling with step down ratio really makes sense with a 26. All else will lead to a too high output impedance for a preamp.

Different story if this is a stage within say a power amp, with controlled, not to low impedance to drive and no cable lengths. I would still prefer transformer coupling in this case but could also live with choke loading. All the other schemes are not really to my taste. Have not tried them all with a 26 though (but with other tubes)

Best regards

Thomas

kevinkr · 8th September 2011, 04:04 PM

Quote:

Originally Posted by FRUGIVO

inside the star #26

As a long time proponent and user of the 26 I am always amazed that such a crude device performs and sounds as good as it does..

(I designed and built my first 26 based transformer coupled line stage 11yrs ago..)

kevinkr · 8th September 2011, 04:11 PM

In terms of reducing hum pick up with the 26, 01, 12, etc in line stage applications I have found it mandatory to use electro-static shielding cans around the tubes. This of course hides them, but also effectively prevents electro-static coupling between the tube's plate and surrounding metal objects potentially with stray AC currents on them. You can find knock offs of the Western Electric style cans on eBay from time to time, that's where I got mine.

5th September 2011, 10:16 AM	#1172
hihopes diyAudio Member Join Date: Sep 2004 Location: Cape Town	26's to spare? Hey, does any kind soul have a couple of pairs of various decent 26's to spare? Or perhaps know of somewhere I can get them for a decent price? (Besides E-BAY. Been watching that for a while.). I will be happy to pay for them (via Paypal). I really, really want to hear for myself this "magic" so many talk about. You can PM me if you'd rather not post on the forum.

8th September 2011, 04:03 PM	#1178
Vinylsavor diyAudio Member Join Date: Feb 2002 Location: Lindau	Hi! I guess the 26 has been loaded by just about everything possible: transformers, chokes, CCS, triodes and pentodes for SRPP, mu-follower, mu stage etc. For me as preamp output only transformer coupling with step down ratio really makes sense with a 26. All else will lead to a too high output impedance for a preamp. Different story if this is a stage within say a power amp, with controlled, not to low impedance to drive and no cable lengths. I would still prefer transformer coupling in this case but could also live with choke loading. All the other schemes are not really to my taste. Have not tried them all with a 26 though (but with other tubes) Best regards Thomas __________________ http://vinylsavor.blogspot.com/

8th September 2011, 04:11 PM	#1180
kevinkr diyAudio Moderator Join Date: Sep 2004 Location: Boston, Massachusetts Blog Entries: 6	In terms of reducing hum pick up with the 26, 01, 12, etc in line stage applications I have found it mandatory to use electro-static shielding cans around the tubes. This of course hides them, but also effectively prevents electro-static coupling between the tube's plate and surrounding metal objects potentially with stray AC currents on them. You can find knock offs of the Western Electric style cans on eBay from time to time, that's where I got mine. __________________ "Extraordinary claims require extraordinary evidence." - Carl Sagan

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5th September 2011, 10:23 AM	#1173
hihopes diyAudio Member Join Date: Sep 2004 Location: Cape Town	BTW, a lot of people have said they are not mad about the sound of LED biasing. I wasn't either, until I tried bypassing the LED string with quite large value low ESR caps. WOW! Different beast. It worked on IDHT's, and even better on 4P1L DHT's too. The new polymer caps are good for this. I used Oscon SEP's 330uF 16v. It seems the better the quality of the valve, the more you have to gain by doing this. I would love to hear the outcome if someone could try it on a 26 preamp or gainstage. You can also bypass the bypass caps with good foil caps for yet another step up in sound. Really worth a try IMHO. Regards, William.

5th September 2011, 12:33 PM	#1175
andyjevans diyAudio Member Join Date: Sep 2003 Location: London	I have a small number of 26 ST, but I'd also recommend 01A and 30 special. I have loads of those so interesting prices. Andy

6th September 2011, 05:16 PM	#1176
FRUGIVO diyAudio Member Join Date: Feb 2010 Location: Burgos	inside the star #26

8th September 2011, 03:15 PM	#1177
hihopes diyAudio Member Join Date: Sep 2004 Location: Cape Town	I hope you didn't drop that on the floor, frugivo! Has anyone tried loading the 26 plate by any other means than resistor or trafo/choke? (Sorry if it has been posted already, but I really can't face wading through all those posts again!)