Dennis Had Inspire Amps

[Rosco65]

Originally Posted by Comzee

I know someone here was asking about the Spatial M4.
I had a chance to listen to the "Spatial M3 Turbo S", which is quite similar to M4, but a bit better.

I used my SE HO Fire-bottle, and I wasn't impressed for the price ($3k).
The M4 base model are ($1700) still more expensive than my Omega Alnico Compact.

The Spatial pair only had one thing on the Omegas, which was bass sound pressure. The two huge subs really do knock, if you like that type of thing, great buy.

If you're into a fuller sound, full frequency experience, the Omegas best it by (imo) a far margin. The Spatial M3 mids were pretty scooped out.

I can see why too, it's only two frequency ranges with a 800hz crossover.
I think the spatial would really benefit from a 3 driver double crossover arrangement. They were missing many nuances from not portraying the full frequency band equally.

Although, this is why I bought my Omegas in the first place, I've only heard one crossover designed speaker I've liked (Magnepan). I have generally disliked any dynamic multi driver crossover speakers (which are REALLY common, almost any tower speaker is this design.)

With regards to how well the 12wpc Fire-Bottle drove the M3 pair, it was exceptional. Unless you like listening at hear numbing levels.

The M3 is spec'd at "94dB - averaged across 200Hz to 5kHz at 1M - on axis". The in-room response may be better, but this illustrates how deceiving published efficiency specs can be. Spatial Audio is essentially publishing midrange efficiency. Actual efficiency may very well be around the 90dB mark.

A lot of currently-marketed speakers (Spatial Audio, Audio Note, Zu Audio, maybe even Devore) are somewhat "optimistic" with their sensitivity ratings. The fact a lot of people are finding 12wpc to be inadequate for a speaker rated at 98dB is a good indicator of that. A true 92dB speaker will provide plenty of output with 12wpc in most rooms.

Generally speaking, we should be able to expect the following maximum efficiency ratings for speakers running reasonably full range (60 hz and above) in reflex loaded enclosures:

15" - 101dB
12" - 98dB
10" - 96dB
8" - 95dB
6" - 94dB
4.5" - 93dB

High efficiency direct radiators generally rely on light cones and large magnets. This combination limits what can be achieved on the low end. The more bass you want the lower your efficiency will be.

[Aercool]

Originally Posted by Musica Amantem

Any thoughts on the Zu Souls?

Thanks for the pointers!

I tried using my Inspire KT-150 for quite a while with limited success with the Zu Omen speakers. For the most part, the experience was quite good - except when there was a demanding bass passage. At that point the Inspire ran out of juice. It got floppy and saturated. There were a couple of CDs that I just couldn't get good solid bass out of the Inspires, and I even tried upgrading to the Soul Supremes - but the result was the same. I loved the Soul Supremes, so it was a lot easier to replace the amp than it was the speakers - so I took the easy route. The First Watt amps are a much better fit for me.

[Bombadil]

The Zu Soul Supreme is the speaker which is spec'ed at 97dB but measured at 91.5dB by Stereophile. So if one ran some calculations on what wattage would be needed to drive them in a certain space to a specific volume level, they would have to increase that estimate by nearly 4X.

[EDIT] I see that Zu is now spec'ing the Soul Supreme at 101dB. However Stereophile measured them this past Spring and I don't think there have been any changes to the speakers since 2013. So I suspect they are still truly 91.5dB. That's a power factor of nearly a 10X difference.

I remember looking them over once to consider getting them for the increased efficiency. My primary speakers are spec'ed at 91dB and measure at 90.5. When I found out that I would, in reality, only be gaining 1dB in efficiency, I scrapped that idea.

[Musica Amantem]

Originally Posted by Bombadil

Stereophile measured two different Zu speakers which were each spec'ed at 97dB. They measured them at 92.5dB and 91.5dB. So that's an average of 5dB under Zu published specifications.

With all these deceptive claims around, it is quite hard to buy or judge anything without hands-on testing. I for one cannot have that privilege and once I get something it can't be feasibly returned due to logistics limitations. I'm getting the drift only horn-based speakers may really be high sensitive, so I'll be looking at those for the future.

[Rosco65]

Originally Posted by Bombadil

The Zu Soul Supreme is the speaker which is spec'ed at 97dB but measured at 91.5dB by Stereophile. So if one ran some calculations on what wattage would be needed to drive them in a certain space to a specific volume level, they would have to increase that estimate by nearly 4X.

[EDIT] I see that Zu is now spec'ing the Soul Supreme at 101dB. However Stereophile measured them this past Spring and I don't think there have been any changes to the speakers since 2013. So I suspect they are still truly 91.5dB. That's a power factor of nearly a 10X difference.

I remember looking them over once to consider getting them for the increased efficiency. My primary speakers are spec'ed at 91dB and measure at 90.5. When I found out that I would, in reality, only be gaining 1dB in efficiency, I scrapped that idea.

The Zu Soul Supreme may have been previously spec'd at 2.83v instead of at one watt, which would account for an extra 3dB of rated efficiency.

In any case, none of these direct radiator speakers come in at the efficiency they say they are. The Devore is actually 91.5 (maybe 94.5), the Audio Note is 91.5, and the tube-friendly Devore Orangutan 0/96 is 91.5. What this tells me is that for a speaker manufacturer to sell a low power tube-friendly speaker, they have to inflate the specs, similar to the "vanity sizing" used in most women's clothing brands.

I think if we redefine what "tube friendly" is, we'll be happier with out speaker choices. For me, this means:

1. 90 dB/watt or greater. This is actually a pretty efficient speaker that works with most tube amps of 5 wpc or more. The classic example of this are the old Snell two-ways from which the current Audio Note speakers are derived.

2. High, flat impedance. 8-16 ohms with a minimum of 6 ohms over any part of the audio band. The very tube-friend Devore Orangutan 0/96 is a nominal 10 ohms with an 8 ohm minimum.

3. Reasonable bass expectations. I think expecting more than 35-40hz from a high-efficiency direct radiator is unreasonable. Big bass requires us to move a lot of air. This is something better handled by active bass reinforcement or really big horn loaded bass drivers.

I can think of a number of speakers that fit this bill. Some examples include:

- All Omega Loudspeakers
- Dynaco A25 and A25XL
- Snell Type E, J, K
- Audio Note Speakers
- Reference 3A Royal Master Control and other models
- Devore Orangutan 0/93 and 0/96
- Harbeth's (though low on efficiency seem to work with low power tubes)

This does not include other, more exotic speakers. The original Quad ESL's did very well with 15wpc tube amps. It also goes without saying that most horn speakers fit this bill. For truly low-powered (flea power) amps of less than 5 wpc, horn loaded speakers are almost a necessity if you want fill a decent sized room or if you music is demanding.

[Musica Amantem]

Originally Posted by Comzee

I know someone here was asking about the Spatial M4.
I had a chance to listen to the "Spatial M3 Turbo S", which is quite similar to M4, but a bit better.

I used my SE HO Fire-bottle, and I wasn't impressed for the price ($3k).
The M4 base model are ($1700) still more expensive than my Omega Alnico Compact.

The Spatial pair only had one thing on the Omegas, which was bass sound pressure. The two huge subs really do knock, if you like that type of thing, great buy.

If you're into a fuller sound, full frequency experience, the Omegas best it by (imo) a far margin. The Spatial M3 mids were pretty scooped out.

I can see why too, it's only two frequency ranges with a 800hz crossover.
I think the spatial would really benefit from a 3 driver double crossover arrangement. They were missing many nuances from not portraying the full frequency band equally.

Although, this is why I bought my Omegas in the first place, I've only heard one crossover designed speaker I've liked (Magnepan). I have generally disliked any dynamic multi driver crossover speakers (which are REALLY common, almost any tower speaker is this design.)

With regards to how well the 12wpc Fire-Bottle drove the M3 pair, it was exceptional. Unless you like listening at hear numbing levels.

That was me. Thanks for the information. That is what I needed to know. Anther one discarded in my book!

[Rosco65]

Originally Posted by Musica Amantem

With all these deceptive claims around, it is quite hard to buy or judge anything without hands-on testing. I for one cannot have that privilege and once I get something it can't be feasibly returned due to logistics limitations. I'm getting the drift only horn-based speakers may really be high sensitive, so I'll be looking at those for the future.

You can't fight physics.

[Musica Amantem]

Originally Posted by Rosco65

The Zu Soul Supreme may have been previously spec'd at 2.83v instead of at one watt, which would account for an extra 3dB of rated efficiency.

In any case, none of these direct radiator speakers come in at the efficiency they say they are. The Devore is actually 91.5 (maybe 94.5), the Audio Note is 91.5, and the tube-friendly Devore Orangutan 0/96 is 91.5. What this tells me is that for a speaker manufacturer to sell a low power tube-friendly speaker, they have to inflate the specs, similar to the "vanity sizing" used in most women's clothing brands.

I think if we redefine what "tube friendly" is, we'll be happier with out speaker choices. For me, this means:

1. 90 dB/watt or greater. This is actually a pretty efficient speaker that works with most tube amps of 5 wpc or more. The classic example of this are the old Snell two-ways from which the current Audio Note speakers are derived.

2. High, flat impedance. 8-16 ohms with a minimum of 6 ohms over any part of the audio band. The very tube-friend Devore Orangutan 0/96 is a nominal 10 ohms with an 8 ohm minimum.

3. Reasonable bass expectations. I think expecting more than 35-40hz from a high-efficiency direct radiator is unreasonable. Big bass requires us to move a lot of air. This is something better handled by active bass reinforcement or really big horn loaded bass drivers.

I can think of a number of speakers that fit this bill. Some examples include:

- All Omega Loudspeakers
- Dynaco A25 and A25XL
- Snell Type E, J, K
- Audio Note Speakers
- Reference 3A Royal Master Control and other models
- Devore Orangutan 0/93 and 0/96
- Harbeth's (though low on efficiency seem to work with low power tubes)

This does not include other, more exotic speakers. The original Quad ESL's did very well with 15wpc tube amps. It also goes without saying that most horn speakers fit this bill. For truly low-powered (flea power) amps of less than 5 wpc, horn loaded speakers are almost a necessity if you want fill a decent sized room or if you music is demanding.

Absolutely!

Are you kidding? Half the speakers in that list are unaffordable! To me anything beyond $2.5K a pair is out of the question, but that's just me.

Good points, though. Problem is, how to tell if those above 90 dB's numbers are true or the impedance distribution across frequencies is flat.

[Rosco65]

Originally Posted by Musica Amantem

Absolutely!

Are you kidding? Half the speakers in that list are unaffordable! To me anything beyond $2.5K a pair is out of the question, but that's just me.

Good points, though. Problem is, how to tell if those above 90 dB's numbers are true or the impedance distribution across frequencies is flat.

- Used Dynaco A25/A25XL - $300
- Used Snell E2 - $3-400
- NEW Omega speakers - almost all monitor speakers are less than $2,300 per pair.

All of the speakers I listed are known to have true >90dB efficiency and high, flat impedance.

[FloridaBoy]

Originally Posted by Rosco65

The Zu Soul Supreme may have been previously spec'd at 2.83v instead of at one watt, which would account for an extra 3dB of rated efficiency.

In any case, none of these direct radiator speakers come in at the efficiency they say they are. The Devore is actually 91.5 (maybe 94.5), the Audio Note is 91.5, and the tube-friendly Devore Orangutan 0/96 is 91.5. What this tells me is that for a speaker manufacturer to sell a low power tube-friendly speaker, they have to inflate the specs, similar to the "vanity sizing" used in most women's clothing brands.

I think if we redefine what "tube friendly" is, we'll be happier with out speaker choices. For me, this means:

1. 90 dB/watt or greater. This is actually a pretty efficient speaker that works with most tube amps of 5 wpc or more. The classic example of this are the old Snell two-ways from which the current Audio Note speakers are derived.

2. High, flat impedance. 8-16 ohms with a minimum of 6 ohms over any part of the audio band. The very tube-friend Devore Orangutan 0/96 is a nominal 10 ohms with an 8 ohm minimum.

3. Reasonable bass expectations. I think expecting more than 35-40hz from a high-efficiency direct radiator is unreasonable. Big bass requires us to move a lot of air. This is something better handled by active bass reinforcement or really big horn loaded bass drivers.

I can think of a number of speakers that fit this bill. Some examples include:

- All Omega Loudspeakers
- Dynaco A25 and A25XL
- Snell Type E, J, K
- Audio Note Speakers
- Reference 3A Royal Master Control and other models
- Devore Orangutan 0/93 and 0/96
- Harbeth's (though low on efficiency seem to work with low power tubes)

This does not include other, more exotic speakers. The original Quad ESL's did very well with 15wpc tube amps. It also goes without saying that most horn speakers fit this bill. For truly low-powered (flea power) amps of less than 5 wpc, horn loaded speakers are almost a necessity if you want fill a decent sized room or if you music is demanding.

Good summary. Have you seen the Oswald Mills Audio site? Not affordable but cool.