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
Trelja, Good answer. Looking at the Thor's crssover designed by Appolito, one can see a simple yet effective design. The thing "just looks right". Its not loaded down with lots of components. Dr Appolito seems to know how to get the most music of the Seas Excel. And he did so successfully.
Newbee I realize that hypothetically it should not matter whether its a 4 OR 8 ohm laod for a "well designed tube amp". But realistically, most tube amps have their limits, depending on how well the trans are made AND the push pull tube on the block. Each tube sings differently and reacts differently to the ohm level. I refer specifically to 4 and 8 ohms, to keep things simply, disregarding 6 ohms.
Ideally tube amps work best on a 8 ohm load. Sure my JOR has driven one beast of a speaker and one moderately heavy load at 4 ohms, which was the Tyler Lin Sig Sys. But the JOR is not built for such loads over a long haul.
Pauly "4 ohms should not be any problem for a tube amp". But in my experience tube amps do not like 4 ohms, especially when the music gets complex, as in orch, even large jazz ensemble is rather thin sounding.
Push pull's , like SET amps can be picky on what speakers they prefer, for best potential.
I'll stay with 8 ohms.
The Tyler Lin Super Towers(8 ohm) is now on my radar and the Tyler Lin Sig Sys(4 ohm) is off.
Thanks Joe for that fine post, crossover network gets overlooked too often. I, like you, want to see whats inside the box BEFORE i buy.
A sealed speaker does me no good. Even if I don't know how the hell a crossover is made.
Paul
Baton Rouge
Thought id throw this in there. Schweikert vr-8. 4 ohm with a dip at 3ohm lowend. 96 db W 1 watt. 300B X4 mono blocks 50 watts each. Clipped the dooit out of them on medium levels.
Rogue 120 monos drove the heck out of them 120 watts.
Hiend, well sure the 300 tube, even at 4 per mono block are not a tube for 4 ohm speakers. So If it takes a beefy amp like Roge, then you lose some finesse somewhere. IOW the delicate 300 monos has the finesse that the Rogue lacks.
btw why mention 96 db at 1 watt? I never fully understood the db thing. I have a general idea ofdecibels at a certain distance.
+++ Pauly "4 ohms should not be any problem for a tube amp". But in my experience tube amps do not like 4 ohms, especially when the music gets complex, as in orch, even large jazz ensemble is rather thin sounding. +++

All things equal I'd go for a higher impedance speaker, yes, but you are quite mistaken by making an across the board statement that tube amps do not like 4 ohm speakers. Decware has some speaker models rated at 4 ohms that are more suited to tube amps than 99% of all 8ohm rated speakers on the market today, and that no exaggeration.

+++ Push pull's , like SET amps can be picky on what speakers they prefer, for best potential.
I'll stay with 8 ohms. +++

A SET amp by definition is single ended and as such not push pull. I do agree that any tube amp, be they single ended or push pull are picky on what speaker they prefer. Where I disagree with you is that nominal impedance has little bearing whether a speaker is suited for use on tube amps. The actual impedance curve and crossover design are way bigger factors you need to consider.

Regards
Paul
Joe and Ralph,
I have Jm labs nominally rated at 8 ohms. They are 936 Electras, wich have dual 8 inch woofers the impedance will drop to 3.6 ohms. I am not sure which order X-over they have but I think they are 2nd order and probably have a fairly involved construction with a large induction coil etc. I also own speakers which are 16 ohms. I have 8 ohm speakers with rock solid 8 ohm impedance curves. None of these even comes close to the inefficiency of the Von Schweickert 2s in the WAF system driven by 40watt PP amp. (yes I know too many speakers and even more feel free to make offers) . Yet Joe as my witness the VR2s play to levels I wouldn't characterize as eye bleeding in a fairly large room 24X 12 X9 but loud enough that my wife always turns the music down whenever she comes into the room. It makes no sense because an average attack of flatulance will overcome the SPL.
I know you have both spent a good deal of effort, time and money on ensuring the bazzing speed that is the essence of what I like about OTLs.
Yet The new tube amps I have, are output transformer coupled and I credit the size of the trannies in them for making the JMs with a " difficult load" during low frequency passages, sound effortlessly extended and clean As loud as I want. I want a lot sometimes around 95- 100db.
Ralph brace youself- Joe has another 60 watt amp but it weighs about 70lbs mostly trannies. I have not found the trannie compromise you mention, the detail, extension are great. I don't care for bone crushing bass below the 28 cycles the JMs are supposed to make. My 16 ohm speakers are vintage JBLs since you like CAR that should have a good idea of that type sound. They are 1959s still as loud as you can take it not distorted using El84 based low powered integrated amps of that era.
My question is why do amps rated at as little as 9 watts per side but with massive trannies make the speaker sing in all but the worst cases, which are generally planars that drop to an impedance equal to a dead short.