Tube substitutions

[unchained]

I just picked up a few used tubes today and I am wondering how they would sound. I have one 12BH7A, one 6BZ7 and a metal can RCA 6L6. AFAIK the 12BH7A is similar to a 12AU7. What would I need to change on the preamp to make either of those work and would the 6L6 sound good?

[Blueburg]

Hiya - these links should give you the info you need to ses if any mods need doing.

http://www.drtube.com/tubedata.htm - good for most common data sheets

http://www.pmillett.com/tubedata/HB-3/R ... 1/6BZ7.PDF - has the 6BZ7 DS

From a quick look the 12BH7A does indeed seem similar to the 12AU7 as it has very low gain, so will typically give a much cleaner sound.

If its in good condition the 6L6 may sound very nice biased right.

Hope this helps, Andy

[zaphod_phil]

What preamp is this? Hopefully, we're talking 18W here. The single 6L6 would be more of a topic for SEwatt.com.

The 6BZ7 is also a fairly low gain dual-triode, somewhere between a 12AU7 and a 12AT7.

[unchained]

It will be an 18 watt with 6v6's, but I thought I's ask about the 6L6 while I was here.

[unchained]

Oh I forgot. I also got two Telefunken 12AX7's and a Mullard 12AU7.

[zaphod_phil]

Telefunken 12AX7s are the holy grail of 12AX7/ECC83s. Maybe even more than Mullards. Treasure those tubes.

You could also use the 12AU7 or 12BH7 as the power stage for a 1.8W Lite II.
http://members.cox.net/dennisfweb/images/18w_AU_3.jpg
http://members.cox.net/dennisfweb/sound/sos.mp3

[JKB]

Telefunken 12AX7s are the holy grail of 12AX7/ECC83s. Maybe even more than Mullards. Treasure those tubes.

Years ago, I repaired lab equipment for the pharma company I worked for. We had spectrophotometers that used 12AX7's and the spares we had were Telefunkens and Philips ECG. The equipment eventually got tossed. I ended up taking home the now "obsolete" tubes. Unfortunately, I had used all of the Telefunkens for repairs. I still have a bunch of the Philips (and one bad Telefunken ).