Zyx Universe. O.24 mv vs .48 mv with low eff spkrs

05-21-14: Dougdeacon
So they're actually just 81db efficient when stated with industry standard specs? Ouch.

Doug, "industry standard" is probably ambiguous in this context these days, as specifying speaker SPLs relative to an input of 2.83 volts rather than 1 watt is pretty common. Measurements presented in reviews often do that as well.

For an 8 ohm speaker (that is really 8 ohms) it makes no difference, as 2.83 volts into 8 ohms corresponds to 1 watt. But 2.83 volts into a 4 ohm speaker corresponds to 2 watts, which results in the SPL number being 3 db higher if the input is 2.83 volts rather than 1 watt.

Since a high quality solid state amp will usually approach or equal being able to supply 3 db more (twice as much) power into 4 ohms than into 8 ohms, specifying relative to 2.83 volts arguably has a somewhat reasonable basis. But tube amps can't do that, of course, so the 2.83 volt "specmanship" can be particularly misleading when a tube amp is paired with a low impedance speaker.

Best regards,
-- Al

If you are married to those speakers, I agree with all the others; you need to select a different amplifier. As a long time Atma-sphere devotee, I would instead choose a speaker better suited to the amplifier. For me, I don't know which came first, because I have been listening to OTLs driving ESLs all my audio life, as a matter of preference. If you should choose to switch to Sound Lab ESLs, I have many useful ways in which to improve dramatically the match between an Atma amp and an SL speaker. In this case, the word "dramatically" is an under-statement, not an exaggeration. I am driving my Sound Lab 845PXs with my highly modified Atma OTL amplifiers, but the modified speaker can be driven to very loud levels by ANY 50W tube amplifier, after modification. In addition to a vast upgrade in efficiency, the modifications also increase the impedance across most of the audio band, not less than 20 ohms from 50Hz to 5kHz. A win-win. Just let me know if you want input on that subject.

Efficiency is pretty important if you want tube power, as tube amplifier power is more expensive. It also does not pay to work your amplifier hard regardless of the amplifier, not if you want to hear the best the amp has to offer.

In my room with speakers of this efficiency I would need over 1000 watts!

I might make a recommendation- talk to Duke at Audiokinesis. He makes reasonably priced loudspeakers that are extremely musical, and also easy to drive with most tube amplifiers. This will solve your sensitivity issues with the preamp and phono cartridge at the same time.

I didn't know the thread was going to weave off into the amplifier end but should have anticipated it

1) I really wanted to go Atmasphere when I heard a friend's M60s - absolutely no grain

2) I found a deal on M1s and bought a pair with Zero Speltz
I should have realized this was a bad match

3) I tried to run the M1s with the Salks and it was clipping but sounded lush on warm acoustic music (think Norah Jones).

4) I bought a volume adjustable QSC 1,500 watt amp to bi-amp the bass freq by ear. Still too much load on the mid and high drivers

5) I bought a Van Alstine 600r 300 watt / 600 into 4 ohm
lots of authority with the Salks (Jim and Frank work together at shows). Robust bass sounds good, but not the Atmaphere musicality.

6)I am looking at Daedalus Ulysses
High efficiency cones not horn
96 db and very natural sounding
Many pair them with Atmaspheres

My Salk's are a museum piece - just beautiful craftsmanship
They are an engaging totally moving speaker and Jim is one of the most stand up guys in audio. I just really like what the Atmas can do

This is an example of thinking through every steep of upgrading and thankfully (if able to) not selling any pieces until you find the right synergy. Buying gear used at good prices and being willing to flip it at a slight loss

I believe the move to Daedalus is the right direction and these speakers also have a very good reputation for sound quality.