Tube amps and speaker ohms

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. :-)

65 wpc might be enough to drive the B&W804S in the frequency where the 3 ohm load is located.

I recently drove my VR4 Gen III HSE loudspeakers with a 55 wpc Rogue Cronus tubed integrated amp. The combo was surprisingly very good. Lots of bass and heft. The VR4 Gen III HSE are 89db/1w/1m, 6 ohm nominal load, with a dip to 3 ohms.

Divad i had a chinese KT88 amp very close in specs to the one you are looking at. I can only speak for my speakers, the amp did not have enough power. Manufacturers can say "amp has X amount of watts". but are they quality watts?
My Jadis Orch Refer rated at 40 watts, blew out the water a Rotel ss amp rated at 100 watts. Go figure. The quality of trans and specs of the tube is everything. In my experience the KT88 tube is better for higher sensitivity speakers.
I only like KT90 and 6550's,. Well I'll hear the 6550 first time in 2 weeks.
Good Luck
Paul
Baton Rouge
btw not a fan of B&W..too british

05-27-07: Bartokfan
In my experience the KT88 tube is better for higher sensitivity speakers.
I only like KT90 and 6550's,. Well I'll hear the 6550 first time in 2 weeks.

This experience based upon the author having never biased any of the tubes.

Properly biasing tubes in a non-biasing tube amp means everything to the proper sound of the amplifier. Without having ever biased the tubes, one cannot legitimately comment on the highs, lows...or any other aspect of a tube's sound.

Sorry to beat this into the ground, but as long as you continue to share your experience listening to tubes in a tube amp which was never biased, then I will continue to caution new readers to take your comments with the appropriate perspective.

Frankly, I very much look forward to the first post you author after you have biased your amplifier. I suspect you will experience such a revelation in good sound that you will be physically shuddering with giddy enthusiasm.