1. Home
  2. amps-preamps
  3. 1179716528

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
tvad
9,467 posts
 

05-25-07: Hiend2
No 40 watts will not drive a 89 db speaker. Push pull or single ended. I have a speaker at 96 db and 200 watts push pull is just enough. Anything less its clippsville.
Perhaps the room size is a significant factor.

I recently took delivery of an integrated amplifer rated at 32 wpc that I am auditioning with 89db/1w/1m loudspeakers. The 30wpc is more than sufficient to drive the speakers to levels into the high 90db range without clipping. I suspect I could go higher.

Transformer quality is everything in a tube amp.
stevecham
3,298 posts
 
Hiend2: I use 45 watts a side from a CJ CAV50 to drive my 86 dB Vandy 2Ce Sigs in a moderately sized room and I have very little trouble hitting my comfort zone of 80 dB in my listening position about 10 ft from them.

I don't know where you get that opinion unless you listen to Metallica at concert levels (120 dB), then it all makes sense.
audiofeil
4,011 posts
 
>>No 40 watts will not drive a 89 db speaker<<

Not true.

Depends on the speaker and the amplifier.
bartokfan OP
664 posts
 
My JOR is,, well the one I sold...is rated 40 watts "conservatively" as they say...does "manage" to drive the 89 db speakers. However since i never biaed the unit, I am not sure there was more highs it could have achieved. On jazz, pop, R7B there was authority. In big complex orch I was always looking for more authority. So the 40 watts was never enough to make the orch "bloom". This is the only reason I sold the amp and looked for more power. I was say a "normal" 40 watt tube amp is not going to deliver the goods on a 89 db speaker. I always felt there was more in the orch that was not comming through.
tvad
9,467 posts
 

05-26-07: Bartokfan
My JOR is,, well the one I sold...is rated 40 watts "conservatively" as they say...does "manage" to drive the 89 db speakers. However since i never biaed the unit, I am not sure there was more highs it could have achieved.
You NEVER biased the tubes in your JOR? Thanks for admitting this. It completely invalidates every post you have ever made about your comparisons of different tubes, including your preference for the KT90.

When you receive your new tube amp, unless it's an autobias model, you MUST bias your tubes for the amplifier to sound as it's supposed to sound.

Inexperienced members of Audiogon who are looking for guidance read posts and take them as gospel, not realizing the egregious errors sometimes made during the testing and listening process.

Readers of your posts deserve better.
More to discover