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Tube amps and speaker ohms

In your opinion , do push pull amps work better with 8 ohms or 4 ohms. .I am under the impression the lower the ohms, the more power is demanded from the amp....Another question, are there low powered SET amps ,and high power SET amps?
I'm looking at a 40 watt 845 tube amp for my 8 ohm, 89 db speaker.. just cked the Thor has a 86 db W18 midwoofers(2 per cabinet) and a 88 db tweeter. Will an 845 amp rated 40 watts be able to drive the 86/88 db speaker? With authority, bass, mids, highs, in dynamic sound stage? Synergy? Or poor match?
bartokfan
newbee
4,767 posts
 
Tvad - FWIW, dealing with like kinds, ie SED's, I found the 6l6GC slightly mellow thru the upper mids/highs compared to the EL34 in both of my Primaluna amps which were primarily designed around the EL34 or the KT88 and to my ears both sound best with that the tube around which it was designed. I've been sort of interested in hearing an amp designed around 6L6's but I haven't found one yet. I tried them in my Baron but they were to hot - I'd have to get it modded (it takes 5881's).

JJ is the only maker of KT77's right now that I'm aware of. On AA several posters have been high on the sound they make, but there is some strong comments on quality control and pin size. FWIW - you probably already knew that.
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trelja
3,223 posts
 
Grant, my KT77 comments are based solely on listening to the JJ variant. I'm not sure how the Osram (didn't know they made KT77) and Mullards would sound.

In my Jadis DA60 and Dennis' (Badboss429) Quicksilver, a bunch of us (including Mechans) compared the JJ E34L blue glass, JJ KT77, vintage 1960s Mullard EL34 XF1 (EL34 Holy Grail), and JJ KT88 blue glass. The KT88 came in last. The rest of the tubes had a variety of opinions. Overall, things seemed to split between the Mullard and JJ E34L, but many of us couldn't get past the powerful, intoxicating lows of the JJ KT77.

From what I heard, the first batch of KT77 had issues with the tube pins. The octet I bought in January/February 20076 had this issue corrected. Didn't have any fail, either, but it's a complaint many have put forth with JJ power tubes in general. I have an octet of E34L Blue Glass, and one day while measuring them about three weeks ago, I found one was as dead as a doornail. That came as kind of a shock.
pauly
1,012 posts
 
Hi Divad. I tried to post before, but I cannot see the post so here goes again.

First off, I am a very pro tube guy, but I would advise you very strongly against going tubes with your speakers. Your speakers are not suited for a tube amplifier.

You may get them to “work” by using a big tube amp, but it is never going to be a good match and neither your speakers nor the tube amp will be sounding their best. You’ll be much better off with a solid state amp.

If you really want to try tubes, you need to ditch the B&Ws.

Regards
Paul
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