Question:
I ran across this tonight.. Anyone ever use this?
http://biasking.com/index.html
Answer:
You don't need that for the HR series, they have a built in bias measurment circuit. Its explained in the manual. All you need is a voltmeter.
Answer:
pushing to amps & acc.
like Major Tom said, you need a voltmeter. I used a Fluke 77 series digital multi-meter when I biased it. I recommend getting one with a digital display, as this will make the readout easier to read. remember that it basically needs to be able to read at least down to 50mV, but also that the GT power tubes are biased much lower than that (I want to say like 44mV) so, a higher resolution (the one I used goes all the way down to 1mV) meter would be better.
Answer:
Or a self-biasing amp. My Traynor does this and some other manufacturers too.
But, if you don't, a voltmeter like has been mentioned would be the reasonable way to go.
Answer:
Originally Posted by Hopeful Or a self-biasing amp. My Traynor does this and some other manufacturers too.
But, if you don't, a voltmeter like has been mentioned would be the reasonable way to go.
AFAIK, amps said to be self biasing amps are cathode biased - that's a different "system" of how the output tubes are biased, it actually changes with the signal, and also has a little bit different characteristic - some say a bit spongier or softer. With a cathode biased amp, you don't need to get it biased when you change tubes. Its actually a relatively easy mod, even with a switch to select between the two systems. I have a couple amps modded that way, but there is very little difference, at least at the amp settings I use.
Most amps that are cathode biased are called "class A" by the mfr, but any tube guru will tell you that they really are not class A - yes that includes AC30's, Matchless, and about every other boutique amp with the exception of single output tube amps which are by nature class A. Its just one of those silly things that started years ago... Perhaps Traynor didn't want to fall into that lie, and wanted to use a descriptive and accurate layman term ("cathode bias" isn't going to mean much to the avg. buyer) or maybe they have some other type of biasing system...?
Hopeful - do you have a schematic for your Traynor? I don't have any Traynor schemos in my collection, I'd like to check that out.
Answer:
Tom - lemme go check and get back to you.
Answer:
Tom - here you are.
YCV40 Schematic
Answer:
Originally Posted by Hopeful Tom - here you are.
YCV40 Schematic
Thanks Bro!
I looked at the schemo, way over my head! It has the most complicated power supply section I have ever seen. It definitely is not cathode biased / "class a", but is a "fixed bias" type (the type you would normally have biased by a tech). The bias supply circuitry is complex, I've never seen anything like that in any other amp, apparently that circuitry is for the self biasing thing. It does show an adjustment pot in the bias circuitry though... I didn't read the rest of the manual to see if it explained that or not... Very interesting.
Answer:
Originally Posted by Major Tom Thanks Bro!
I looked at the schemo, way over my head! It has the most complicated power supply section I have ever seen. It definitely is not cathode biased / "class a", but is a "fixed bias" type (the type you would normally have biased by a tech). The bias supply circuitry is complex, I've never seen anything like that in any other amp, apparently that circuitry is for the self biasing thing. It does show an adjustment pot in the bias circuitry though... I didn't read the rest of the manual to see if it explained that or not... Very interesting. on the website, Traynor/Yorkville describe the YCV20 as class A...but I don't believe them.