Horns with SS amp instead of Tube (se)!?

[ddk]

Hi DDK,
Interesting comment, as I believe that Avantgardes are something like 105 or 107 db efficient, and it has something like a 500 watt amp driving the bass. Any chance you can please elaborate?

Yes, I've seen the claims but I have no idea how they measured the speaker to come up with those figures nor have I seen full measurements to know how the speaker behaves but I know what I heard. The active bass unit has it's own issues and will never blend with any good tube and SET amps. Posted sensitivity numbers mean little on their own.

david

 

[Alrainbow]

Yes, I've seen the claims but I have no idea how they measured the speaker to come up with those figures nor have I seen full measurements to know how the speaker behaves but I know what I heard. The active bass unit has it's own issues and will never blend with any good tube and SET amps. Posted sensitivity numbers mean little on their own.

david

I think this is how ...?

https://www.stereophile.com/content/avantgarde-acoustic-uno-series-two-loudspeaker-measurements

Hifi News also confirmed years later ..

https://www.hifinews.com/content/avantgarde-acoustic-uno-xd-loudspeaker-lab-report

Normalized to 8ohm its estimated at 105 db

 

[wil]

My Mezzo Xd’s are rated at 107 by AG. I don’t know how accurate that is but I can tell you from experience that the LTA Mz3 which produces ONE WATT per channel ran them with ease and plenty of headroom in a 16 x 45‘ room.

 

[Alrainbow]

The shrill is caused by distortion introduced by the feedback. The only way around this is to have a lot of feedback, north of 35dB or more- at that point the amp can then compensate for the distortion caused by the feedback (which tends to be higher ordered harmonics). Most amps simply lack the Gain Bandwidth Product and Phase Margin to add that much feedback!

I thought the honky shrill sound of horns were cause from over driving them and causing resonance in the throat area with increasing THD ..

Hard to do with under powered tube amps ..

 

[ddk]

I think this is how ...?

https://www.stereophile.com/content/avantgarde-acoustic-uno-series-two-loudspeaker-measurements

Hifi News also confirmed years later ..

https://www.hifinews.com/content/avantgarde-acoustic-uno-xd-loudspeaker-lab-report

Normalized to 8ohm its estimated at 105 db

Hi Al,
These links aren’t for the Trios, also to be clear I was talking about 1st generation AV Trios, don’t know if anything is different about the current ones.
david

 

[Alrainbow]

No problem thought the uno being smaller may have settled it ..

 

[Duke LeJeune]

I thought the honky shrill sound of horns were cause from over driving them and causing resonance in the throat area with increasing THD ...

Audible distortion can be caused by several different things in horn-based systems, but "over driving them" is very rarely one of those things.

The sound pressure levels involved in "over driving" the throat of a horn, or "over driving" a compression driver (assuming adequate crossover protection), are very high.

Chances are some other distortion is being mis-identified as "over driving", perhaps because it becomes more audible and objectionable as the SPL rises, but that could be because it is a type of distortion to which the ear itself has a non-linear response.

 

[morricab]

Audible distortion can be caused by several different things in horn-based systems, but "over driving them" is very rarely one of those things.

The sound pressure levels involved in "over driving" the throat of a horn, or "over driving" a compression driver (assuming adequate crossover protection), are very high.

Chances are some other distortion is being mis-identified as "over driving", perhaps because it becomes more audible and objectionable as the SPL rises, but that could be because it is a type of distortion to which the ear itself has a non-linear response.

It could be over driving a 1 watt amp into clipping I guess or the AV horn design has a fairly high level of what Geddes termed HOMS.

 

[wil]

It could be over driving a 1 watt amp into clipping I guess or the AV horn design has a fairly high level of what Geddes termed HOMS.

If you haven't heard the AV driven by the 1 watt MZ3 then you're only speculating. I can tell you it drove them easily and cleanly. I never tried them at 100+ db though as I don't listen at that level.

Could you could share what HOMS stands for?

 

[Solypsa]

Geddes research on horns led him to focus on High Order Modes or hom's. I believe his findings are published somewhere...

 

[Alrainbow]

Audible distortion can be caused by several different things in horn-based systems, but "over driving them" is very rarely one of those things.

The sound pressure levels involved in "over driving" the throat of a horn, or "over driving" a compression driver (assuming adequate crossover protection), are very high.

Chances are some other distortion is being mis-identified as "over driving", perhaps because it becomes more audible and objectionable as the SPL rises, but that could be because it is a type of distortion to which the ear itself has a non-linear response.

The paper i read on it described this as distortion in the throat and produces the shouty character as described. Im assuming clipping will do the same as easy to overdrive then and BTW anything can be “overdriven” ..

Anyway im suggesting this is why some may favor low powered amps over high powered on horns , also most are using simple 6db slopes very little out of bandwidth protection there ..

 

[Alrainbow]

It could be over driving a 1 watt amp into clipping I guess or the AV horn design has a fairly high level of what Geddes termed HOMS.

Dont all horns suffer from HOMS , why geddes and others sacrifice some sensitivity in favor of waveguides ..

 

[Atmasphere]

Which Class D might those be? I am far from ignorant when it comes to Class D having owned 3 different technologies and heard at length many more but none sounded what would call natural. There was always a dryness that one never hears with live unamplified music...or a good tube amp for that matter.

The amp I heard is a prototype. But it was clearly class D. It did not sound dry to me- nor to my GF.

The paper i read on it described this as distortion in the throat and produces the shouty character as described. Im assuming clipping will do the same as easy to overdrive then and BTW anything can be “overdriven” ..

Anyway im suggesting this is why some may favor low powered amps over high powered on horns , also most are using simple 6db slopes very little out of bandwidth protection there ..

My horns employ 6dB slopes- but also employ Kapton surrounds on the drivers. As I recall, there was a change that John (of Classic Audio Loudspeakers) did to the throat design that made it dramatically smoother (he used to use a TAD machined maple horn, but came up with his own that has the computer-optimized throat design). Even at 105dB it sounds relaxed. I think it does at 110dB too, but at that point I was using earplugs..

 

[Duke LeJeune]

Geddes research on horns led him to focus on High Order Modes or hom's. I believe his findings are published somewhere...

Higher Order Modes (HOMs) are reflection and/or diffraction paths within a horn. They are not predicted by Webster's horn equation but are predicted by Earl Geddes' more modern waveguide theory.

The proportion of HOMs produced by a horn does not change with level, so it is a linear distortion. But HOMS become increasingly audible and objectionable as the sound pressure level increases. This because the ear actually has a non-linear perception of this type of distortion; that is, it sounds like the distortion increases disproportionately as the sound pressure level goes up. Because of the time delay caused by the HOMs travelling a slightly longer path before reaching the ear, they are not effectively "masked" by the original undistorted signal, and so as the volume level goes up the HOMs become more audible and therefore more objectionable. HOMs tend to sound like edginess or harshness (which increases with SPL), which is probably why they can be mistaken for driver or horn throat being over-driven.

Abrupt angular changes within a horn, like diffraction slots, are strong sources of HOMs. Gentle curvatures are more benign. The curvature which generates the weakest HOMs is the Oblate Spheroid, according to Geddes, though apparently some of Jean-Michael L'Cleach's horns also generate very low HOMs. The junction between compression driver and horn can be a major source of HOMs if there is a significant angular mis-match there.

Imo taking steps to minimizing the generation of Higher Order Modes pays dividends in reducing "horn sound".

 

[ddk]

The amp I heard is a prototype. But it was clearly class D. It did not sound dry to me- nor to my GF.

My horns employ 6dB slopes- but also employ Kapton surrounds on the drivers. As I recall, there was a change that John (of Classic Audio Loudspeakers) did to the throat design that made it dramatically smoother (he used to use a TAD machined maple horn, but came up with his own that has the computer-optimized throat design). Even at 105dB it sounds relaxed. I think it does at 110dB too, but at that point I was using earplugs..

So you haven't heard any commercial digital amps that sound musical and natural?
david

 

[Folsom]

So you haven't heard any commercial digital amps that sound musical and natural?
david

Soo... If he hasn't enjoyed a classD, what makes you think he'd like digital amp? (whatever digital amp is, not sure)

 

[ddk]

Soo... If he hasn't enjoyed a classD, what makes you think he'd like digital amp? (whatever digital amp is, not sure)

I meant class D. Years ago there was a company I think called Spectrum which call their amps digital and it's stayed with me, and I think digital whenever I see class D . It's the same family of sound anyway.

david

 

[Folsom]

I meant class D. Years ago there was a company I think called Spectrum which call their amps digital and it's stayed with me, and I think digital whenever I see class D . It's the same family of sound anyway.

david

Well, Spectrals have a "digital" sound to me. I thought maybe you meant some sorta Gryphon or something with a DAC in it.

 

[ddk]

Well, Spectrals have a "digital" sound to me. I thought maybe you meant some sorta Gryphon or something with a DAC in it.

Not Spectral, Spectrum or something like, they're not around anymore.

david

 

[bonzo75]

Not Spectral, Spectrum or something like, they're not around anymore.

david

Spectron?