Tube amps and speaker ohms

I just checked the biasing on my TAD-60 as I just changed an output tube and had to make adjustments to get the balance right as it did not sound right after I changed the tubes. Turned out I had to readjust two out of three tubes. Then I checked the sound and it sounded nice and balanced again... So, I agree with TVAD that you have to check the bias either every six months as Paul Gryzbek recommends or when the music doesn't sound balanced... On the TAD-60, Paul supplies you with a $10 meter and gives you instructions on biasing the unit. On the 07s, the biasing meter is on the unit...

Eagleman

Tvad, ROTFLMAO. Don't hang around any crosses. You are far too nice.

Bartockfan, may I suggest that before you burden the forum readers further with your 'experience' using tubes that you take some time to read about tube technology and get some understanding of whats actually going on. You might just learn what the benefits of properly biasing tubes are and what the risks of not properly biasing your tubes are. Its got nothing to do with getting "a tad more highs" as you seem to think.

Hmm, I was just about to buy my first tube amp but am unsure now, after reading this thread. I'd be grateful for any comments on whether the following would work together.

My speakers are B&W 804S's - 3 way vented box design. They are rated as having a 90db sensitivity and a 'normal' impedance of 8 ohms. But, the minimum is impedance is quoted as being 3.0 ohms. I know that some say they need a powerful amp to work at their best, but they have been fine with my 35wpc Class A Sugden A21SE.

The amp I was thinking of purchasing (to get a taster of tube amps) is a Yaqin MC-100B. This is a chinese brand and employs 4 x KT88 tubes. It is rated at 65wpc in ultralinear mode, or 45wpc (into 8ohms) in its standard mode. I'm not clear what ultralinear is all about, but do you think this combo would work?

Divad, You might consider posting a new thread - I think a lot of folks not already signed into this one will open it and see it, and some of the more knowlegable folks that have posted probably may not be following it any longerby now.

I think it is possible (actually quite probable) that a tube amp with a wattage limitation of 65 in Ultralinear can drive a 90db speaker depending on the actual impedence curve of both the amp and the speakers and how they interact. Your nominal impedence and minimum impedence are not ideal for just any old tube amp, unfortunately.

Usually ultralinear is going to be a bit more forward/focused and triode will be a little more recessed and relaxed. Usually, but this is very amp dependant, and either mode can better fit with certain speakers that the other. I have a 'triode amp' which sounds neither laidback nor unfocused, and responds much as another amp I have when its in ultraliner.

Your speakers are fairly well know (to others) but you prospective amp is not. I would suggest that you post here and on Audioasylum and try to find folks who have actually used a tube amp with your B&W so you can find out what they need to drive them.

If you can find out, it is helpful to know exactly where your speakers minimum impedence droop appears (at some frequencies it won't be near as important as others) and if you can find out the maximum output impedence of the amp and at what frequency it appears. With that info there are some very knowlegable folks about who can give you some advise.

I hope this helps a bit, I know it really doesn't do much to specifically answer your question. But, if you are a gambler, you can afford a buy and sell loss should you be unhappy, and you are not a bass nut (thats usually where you will run into problems) you can always get a tube amp and drive it off its 4ohm tap and hope for the best. :-)