?? dB=<88 loudspeaker and SET like Aries Cerat Diana Forte; how does this match?

Aries Cerat

Industry Expert
May 30, 2015
209
142
128
#21
Your last question is easy , people use them because they can be made to sound better than over damped , high distortion shouty high sensitivity speakers with no sense of space and timing ...

Errr , just saying ... :)
Agree on someone's poison is another's euphoria.
But,are we really stuck between heavy coned 88db 2ohm speakers and "ww2 shouty things" ?
Also I would really like to see data on the high distortion thing.we can debate about timing and why usual(but not all) designs suffer all day long,but the distortion comparison is pretty much settled.Not in the direction you think though..

Cheers
Stavros
 

Atmasphere

[Industry Expert]
May 4, 2010
968
180
455
St. Paul, MN
www.atma-sphere.com
#22
As I recall, the distortion of a horn is based on how well it adheres to an ideal design curvature; these days because... computers that is usually very well indeed. At that point the distortion comes down to the driver, and since that tends to not have a lot of motion (nor thermal compression) it tends to be low distortion too. The idea that high efficiency speakers are shouty is to me ridiculous.
 
May 30, 2010
16,856
1,659
720
Portugal
#23
As I recall, the distortion of a horn is based on how well it adheres to an ideal design curvature; these days because... computers that is usually very well indeed. At that point the distortion comes down to the driver, and since that tends to not have a lot of motion (nor thermal compression) it tends to be low distortion too. The idea that high efficiency speakers are shouty is to me ridiculous.
The issue on simulation is the definition of the parameters that control how well it adheres to an "ideal curvature" and even what is objectively the ideal curvature. Simulation is not a miraculous process - computer simulations depend on the constrains we impose on them.

Bjørn Kolbrek is a very good current reference on this simulation subject - see his homepage https://kolbrek.hornspeakersystems.info/ . His book High Quality Horn Loudspeaker Systems 2019: History, Theory and Design has excellent buyer reviews, but seems sold out.
 

Atmasphere

[Industry Expert]
May 4, 2010
968
180
455
St. Paul, MN
www.atma-sphere.com
#24
The issue on simulation is the definition of the parameters that control how well it adheres to an "ideal curvature" and even what is objectively the ideal curvature. Simulation is not a miraculous process - computer simulations depend on the constrains we impose on them.

Bjørn Kolbrek is a very good current reference on this simulation subject - see his homepage https://kolbrek.hornspeakersystems.info/ . His book High Quality Horn Loudspeaker Systems 2019: History, Theory and Design has excellent buyer reviews, but seems sold out.
I was not referring to simulation, I was referring to the fact that even 50 years ago it was well understood that the curves used to create the flair in a horn had an effect on its distortion. This sort of thing has been optimized by newer manufacturing techniques- it a nutshell, its easier to get the flare correct.

I agree about the simulation thing 100%!!
 
Likes: adyc
May 30, 2015
209
142
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#25
The sim is only as good as the assumptions made in the model and what the programmer used as "facts" regarding horn mathematics.Usually sims do not have info on how a horn body resonates ,how the termination behaves(diffraction) and assumes perfect transition from driver diaphragm to horn throat,which is not real world scenario.

Some of the manufacturing techniques used today were none existing before,techniques with now make the deviation of the real thing from the mathematically ideal almost none existent.It was nearly impossible to make round horns true to flare down to the 0.1mm using equipment of the time.

Imagine a horn starting from 18mm diameter throat , to 1.2m mouth, 2m length.Round not rectangle,10cm mimimum thickness of the walls, with a real flare true to the decimal of the millimeter to the ideal tractrix flare. Almost impossible to manufacture even today,so much for the WW1-WW2 era. BUT is manufactured today.Listening to one right now :)

Driver development is another story,we went forward and backwards in a lot of things.

But the proof is in the pudding. A 110db 100Hz horn with proper driver will have 30 times LESS distortion on it's two octave ideal range than any cone driver,especially in real life sound pressure levels,not kitchen listening levels.

Cheers
Stavros
 

morricab

Well-Known Member
Apr 25, 2014
4,561
1,130
388
Switzerland
#27
Hello there.Happy to answer.

Tubes in general have lower distortion , the higher the load is.Correct.
In OTL designs, the tube "sees" a load (the speaker load),divided by number of tubes. If the load is halved,then the number of tubes must be doubled, if we want for each of the tube in the output stage to see the same impedance as before.

However
A transformer is an impedance matcher.The load that each of the tube "sees" is the impedance of the load multiplied by step down ratio squared.

For example, a tube in a SET output stage, will "see" a 8 ohm load as 5000ohm if a 25:1 step down is used. If the load becomes 4ohm, and if we keep the same step down ratio of 25:1, the reflected load will be 2500ohm.

In that case,obviously the tube will suffer from reduced power and higher distortion level.
Now,if we increase the step down ratio by a factor of 1.4 ,the reflected load will be again 5000ohm.Tube is happy again,delivering same power and same distortion as in the 8ohm load.

Now,how this is done( the increase in step down ratio of the OTP) , is where the whole game is.Sub par solutions end up with lower bandwidth and/or higher copper losses.But there are some techniques/solutions then bend around these issues.

A tube stage loaded with a step down transformer has absolutely no problem delivering extremely low distortions and high power even down to 0.1ohm, if the transformer is designed for that purpose.

Cheers
Stavros
I remember Allen Wright designed a tube amp specifically to drive 1 ohm Apogee Scintillas. Sounded darn good doing it too...
 

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