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

Do you ever want to crank the volume beyond the highest setting you have available?

getting close to wanting to, it is usually just enough for my louder listening, but I have to use a hi watt amp (Van Alstine 600r)

As a point of information, the 84 db/2.83 volts/1 meter/4 ohm specs of the speaker correspond to only 81 db/1 watt/1 meter.

The Van Alstine amp, having a solid state output stage, will presumably be capable of delivering considerably more power into 4 ohms than the 300 watts it is rated at (presumably into 8 ohms). But I suspect that the power capability of the MA-1's will not be a whole lot greater than their 140 watt/8 ohm rating regardless of what transformation ratio you choose on the Zeros you appear to be using with them.

140 watts into 81 db/1W/1m speakers will just get you to maximum SPL's of around 95 to 98 db at a listening distance of around 10 feet, neglecting room reflections, and less than that at greater distances. That will be enough for most listeners for most recordings, but I suspect it will not be enough to cleanly handle the dynamic peaks on some of the symphonic recordings you mentioned that you listen to.

So using those speakers with the Atmasphere amps + Zeros may leave you with a power shortfall even if the gain issue were somehow resolved. While with the Van Alstine amp you have a gain marginality and probably also some degree of sonic compromise. Depending on the input impedance of the Van Alstine amp you MIGHT be able to resolve the gain marginality, without introducing significant additional sonic compromise, by putting a suitably chosen Jensen transformer having a 2:1 step-up ratio between the preamp and power amp. Doing that would give you close to 6 db of additional gain (equaling the volume increase that would result from going to the HO version of the cartridge), but would result in the preamp seeing a load impedance equal to the input impedance of the power amp divided by 4, which may or may not be acceptable. (There does not appear to be a spec on the input impedance of the amp).

However, given the extremely high quality of your turntable setup, your preamp, and of the Atmasphere amps you apparently still have, I would have to agree with the previous posters that what would make the most sense is to replace the speakers with ones that are both more efficient and higher impedance (and are also known to work well with OTLs), and selling the Van Alstine amp.

Regards,
-- Al

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

05-21-14: Charles1dad
I believe the move to Daedalus is the right direction and these speakers also have a very good reputation for sound quality.

Well, as a very happy Ulysses owner I'll certainly second that.

BTW, Tom, they are spec'd at 98 db/1 watt/1 meter, rather than 96. Also, although their impedance curve is exceptionally flat, and impedance phase angles are apparently very benign, you might still find it to be sonically preferable to utilize the Zeros with your MA-1's, most likely connected to provide a 2:1 impedance transformation. I say that particularly because while Lou's website does not indicate the impedance of the currently produced Ulysses version 2, the Ulysses v.1 which I have were spec'd as being 6 ohms. But either way (Zeros or no Zeros) I'd expect the Ulysses and the MA-1 to be a fine match.

Best of luck as you proceed. Regards,
-- Al

Thanks for the update, Tom. I recall, as you're probably aware, that Thom uses the Ulysses as his reference speakers.

Enjoy! Regards,
-- Al

05-22-14: Dougdeacon
Almarg,

Thanks as always for your willingness to share technical knowledge. Most of my postings are based on what I hear and seat of the pants "thinking". It's always helpful to hear from someone who actually understands what he's talking about.

Thanks, Doug. And likewise with respect to your uncommonly knowledgeable posts about turntables/tonearms/cartridges/vinyl.

Best regards,
-- Al

05-23-14: Swampwalker
My own experience is that you do have to be somewhat concerned about hum and noise when you go to very high eff speakers; the higher eff the more careful you have to be....

Relevant to this point I see that the MA-1's description (under the "order" tab) indicates that the following are available:

Jumper plugs for high efficiency speakers -- Replaces tube in the voltage amplifier section of Atma-Sphere power amplifiers, thus reducing gain for high efficiency speakers. Recommended when efficiency of speaker is over 100.

As I indicated earlier the efficiency of the Ulysses is spec'd at 98 db/1W/1m, and I suspect that you won't have any issues with hum or hiss. But considering the high gain of your preamp I wouldn't completely rule out the possibility that you might find yourself operating the volume control undesirably close to the bottom of its range. In which case these jumper plugs would appear to be a solution.

Enjoy! Regards,
-- Al

Swampwalker's advice and Ralph's clarification are spot on!

+1, in both cases.

With the slight qualification that the hum and noise which will be reproduced at a higher SPL by a speaker having higher efficiency is hum and noise that is generated or introduced at points in the signal path that are "after"/"downstream of" the volume control.

Best regards,
-- Al