[Ericus Rex]

Anyone tried any of these oddball 6SN7 substitutes:

6BL7, 6BX7, 5692, 6180, or others?

How'd they compare, in your piece, to the 6SN7?

[Niteshade]

Stick with these:

6SN7
6SN7GT
6SN7GTA
6SN7GTB

The A & B models have a higher plate dissipation, something like the 6BX7 you referred to, but not quite as high as they are. I have used the A & B in place of the GT's and have not found any noticeable difference. The 6BX7 may be an interesting tube to try and drive something like a 572 with.

[JakeJ]

Good catch, Blair.  The 6BL7, 6BX7, & 6180 are not direct substitutes for the 6SN7.  When in doubt check the tube data sheets.  Here is one of many resources available.

http://tdsl.duncanamps.com/tubesearch.php

You enter the tube code and hit the query button.  You'll get a list of the tube(s) you searched on.  Click on any link and you will get a diagram of the tube along with a list of direct subs.  At the bottom of that page are links to actual manufacturer tube data sheets that list all the parameters that tube was/is designed for.  These parameters must match unless you are intimately familiar with the circuit you want to use it in and even then you should always be prepared for disaster.   Note that none of the other tubes you mention are listed.

Last but not least consult the manufacturer of the circuit you want to try out a different tube in.

Hope that helps and keeps you from creating a miniature fireworks show in your gear. 

[JohnR]

In particular, the 6BL7 and 6BX7 have much higher heater current than the 6SN7.

[JakeJ]

Kudos, sir. And thank you.

[Quiet Earth]

How about the Russian 6H8C? Anyone tried these yet? I think they are a direct substitute....

I need to try a pair. 

[doug s.]

How about the Russian 6H8C? Anyone tried these yet? I think they are a direct substitute....

I need to try a pair. 

yes, they will fit.  6h8c's come stock in the audio mirror amps.  at least they used to - vlad may have chenged; i dunno.  (as well as 6h9c's instead of 6sl7's.)  here's one (of many) posts on the web about the 6h8c tubes:

http://www.audioasylum.com/cgi/t.mpl?f=tubes&m=204585

supposedly, the 5692's are the best iteration of the 6sn7 tubes.  (w/5691's being the best of the 6sl7 type.)

doug s.

[Ericus Rex]

Very interesting about the BL and BX.  Those recs came from this site:

http://www.gini.com/index.php?id=176

I thought everything on the 'net was true and reliable   

Very glad I axed you guys first before trying them out!

Those 6h8c tubes are nice and cheap, just like me!  How do they sound?

[JohnR]

What are you putting them in?

[JakeJ]

Very interesting about the BL and BX.  Those recs came from this site:

http://www.gini.com/index.php?id=176

I thought everything on the 'net was true and reliable   

Very glad I axed you guys first before trying them out!

Those 6h8c tubes are nice and cheap, just like me!  How do they sound?

No problem!  Axe me anything you want and I'll "chop" you out an answer. 

[Ericus Rex]

What are you putting them in?

My Rogue Audio 99 pre uses 2 - 6SN7s/channel in Mu-follower config.  My Rogue Stereo 90 uses 1 6SN7/channel as a driver to KT90s (currently).  I was hoping to try some very inexpensive NOS subs but it appears to be a no-go.  The 5692s are way more expensive than their 6SN7(GTx) brethren.

[doug s.]

My Rogue Audio 99 pre uses 2 - 6SN7s/channel in Mu-follower config.  My Rogue Stereo 90 uses 1 6SN7/channel as a driver to KT90s (currently).  I was hoping to try some very inexpensive NOS subs but it appears to be a no-go.  The 5692s are way more expensive than their 6SN7(GTx) brethren.

yes, 5692's are spendy.  re: sound of 6h8c's, my audio mirror amps were purchased used, and no 6h8c's were present.  you may want to query vlad bezelkov of audio mirror about these tubes; he should have some worthwhile info...

doug s.

[siliconray]

6H8C or Chinese shuguang 6N8P works great as cheap sub of 6NS7.

[DaveC113]

I got these 6H8C for my Aikido preamp build:

http://www.ebay.com/itm/200718957251?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649

And these Sylvanias:

http://www.ebay.com/itm/261024910283?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649

On the 6H8C, from what I read you want to get the tubes made in Tashkent at the Foton plant rather than the later production tubes... they are about $5 rather than $2 each, but in this case buying tubes that cost 2.5 x as much isn't a big deal.