• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

300B+

ThorstenL

Previously: Kuei Yang Wang
Re: datasheets

Konnichiwa,

rick57 said:
OT: I see there is a big $ “300B+ Premium Graphite Plate” they claim: “With 1K5 OPT and 400/120ma, fixed bias you can get a whopping 20+ watts from these: 845 slayer”!

Well, I have been tinkering around with Brian on this, a better choice of OPT on this is around 2K4 and 120mA, up to 450V. This gives a nice 18W at lowish THD (competent driver deign assumed) and if you want to rate it 20W simply allow more than 3% THD.

The old stock 50's aparently sound very good but are hard to implement right.

Sayonara
 
Re: Re: datasheets

Kuei Yang Wang said:
Konnichiwa,



Well, I have been tinkering around with Brian on this, a better choice of OPT on this is around 2K4 and 120mA, up to 450V. This gives a nice 18W at lowish THD (competent driver deign assumed) and if you want to rate it 20W simply allow more than 3% THD.

Sayonara

KYW is right. Our first tests were with the factory recommended 1k8 OPT and only got about 12-13watts. But we've just installed the 2K4 OPT and now getting 20w both 4 and 8 ohm before the onset of clipping, 110ma/410v.
I'll amend the info on the website.
It is exciting to think we can get this amount of power with such low operating points.
Brian
 
Re: questions for Brian

rick57 said:
Brian

What B+ with the super 300B gives 18w?

Will datasheets of the TJs be put on your website?

And have listening comparisons been done of the new 50s v NOS?
;)

Cheers
400v/100ma

Gordon Rankin: "The TJ mesh sound is pretty similar in comparison to the sound of the TJ Mesh 300B. The nice thing over the 300B is that it appears to have more umph. Which I think can be attributed to the higher potenial energy in the filament. The NOS RCA and TungSol I have here are a bit more clearer, focused and extended, but not as powerfull. In general I prefer the NOS over the TJ, except for the price. If you are looking for a more romantic sound I would go with the TJ."