orphean for 220hz high-pass not too small ? (Orphean)
Hi Bert
to cross at 300hz, is the Orphean Horn not too small ?
here the comment from Jean Michel LeCleac'h :
- in order to operate the horn inside a frequency range for which the acoustical impedance of the horn is mainly resistive (and not reactive in order to avoid phase distortion) we have to use a high pass frequency an octave minimum above the acoustical cut-off frequency of the horn. This means that for a tractrix horn used above 500Hz, the acoustical cut-off should be 250Hz. If we consider a complete tractrix horn opening at 180 degrees this means a horn having a 433 millimeters diameter.
Please notice: classical empirical formulas giving relations between cut-off frequency and diameter give a minimum diameter. IMHO thet can be useful in the pro domain where a smaller volume is desired. In the hifi domain they should be avoided.
That meens, to have a high-pass frequency at 300hz, there should be used a 150hz horn with 68cm diameter. If high pass it is 220hz,as you state for the orphean, the horn should have 88cm diameter optimal, no ?
rds Angelo
orphean for 220hz high-pass not too small ?
by Bert 
, Monday, June 04, 2007, 09:13 (6169 days ago) @ angeloitacare
Angelo,
That meens, to have a high-pass frequency at 300hz, there should be used a
150hz horn with 68cm diameter. If high pass it is 220hz,as you state for
the orphean, the horn should have 88cm diameter optimal, no ?
No, as usual you only highligth one issue at the time disregarding all other related things which combined makes things work as a system.
But, be my guest and built a bigger horn which does give a better loading at lower frequencies.
Bert
--
BD-Design - Only the Best!
orphean for 220hz high-pass not too small ?
by PeterSt. 
, Netherlands, Monday, June 04, 2007, 09:28 (6169 days ago) @ angeloitacare
Hi Angelo,
Just a question : Earlier you planned to create your own (wooden) bass horn. Any ideas about the throat diameter of that ?
I could also propose to you this situation :
Suppose the "best" full range driver stops at 17K.
As an alternative we can use two drivers with a crossover which of course is prone to phase distortions in the xover area.
What would you choose ?
Peter 
PS: I'm not implying anything with my questions towards the techniques used in the Orphean. What I do say, however, is dat theoretical compromises should be experienced in real practice and be hold against the alternatives.
My 2c.
Edit : Crossposted this with Bert's post.
orphean for 220hz high-pass not too small ?
i am doing my projects, one at the time. When the ongoing one is finished, i start with the horns. Next will be a mid-bass horn, and a midrange horn. I do not have yet practical experience, i am still at the very beginning, so i rely on others knowledge. Regarding the horn size, i would like to mention also a other expert, witch does say practicly the same thing as JMLC, but in other words :
Make an experiment, and I will simplify the case quite assertively. Take a typical compression driver, cross it at 800Hz, second order and load it into a proper contemporary horn (Tratrix or JMLC) of 300Hz. Listen that horn, you will get some sort of sound that let accept as OK Sound. Now begin to very slow lower the crossover point and keep listening the channel. While you lowering the crossover point, somewhere around 550Hz (I took this number purely arbitrarily as it would depends from VERY MANY circumstances) the horn will begin to demonstrate what I call “choked sound”. The “choked sound” is HOW HORNS SOUND IN 99% OF ALL HORN INSTALLATIONS OUT THERE – people just too **** to deal with it. The “choked sound” is the satiation when Sound produced by a driver can’t be “processed” by horn. In this “choked mode” a horn produces the “sonic boom” that was made by the horn’s bell and that “sonic boom” screw up the enter band-pass of the channel - the game is over. Increasing of the crossover point for ¼ octave (for instance) will fix the situation - so we have approximately one octave between horn’s rate and mix crossover point…
Bert
what negative consequences do you think would imply following this rool ?
Angelo
orphean for 220hz high-pass not too small ?
by Bert , Monday, June 04, 2007, 12:15 (6169 days ago) @ angeloitacare
Angelo,
what negative consequences do you think would imply following this rool?
None, you can't go wrong for the lowest crossover frequency if you work around that way.
Bert
--
BD-Design - Only the Best!
orphean for 220hz high-pass not too small ?
Angelo,
I do not have yet practical experience, i am still at the very
beginning, so i rely on others knowledge.
Right now, you rely on other people's opinions. Do you know if they are right or wrong? How will you check?
You have read a lot about horns in a very short time. I admire that and I think you may have the potential to make a really nice system some day, because you are dedicated. But you won't get anywhere just by reading about and listening to other people's opinions.
What you need, is to make some prototypes. You have to test some of the theories and highly personal opinions. Only then can you get a clear idea about how things work, how they sound, what works and what doesn't. I will tell you now, there's probably no such thing as the "only right mouth". Just as there isn't the only right throat, the only right driver, the only right material, the only right position... It's all about combinations.
The thing with Bert is, he has tried a lot of things. He actually knows, from experience, how certain materials will colour the sound, what effect a certain horn throat or horn mouth have on the frequency response. Ask him a question, he will give a solid answer. Bert's design philosophy is simple: keep it as wideband as possible and keep it living room friendly. Those are his reasons and his choices. What comes out are the Oris horns.
I respect JMLCleach as well and I have read things written by him about horns. You must keep in mind that he uses a very different horn expansion than tractrix. It gives much less loading in the lower frequencies. He will need a bigger horn to reach lower. Also, he is a cross-over artist, which means that he wants predicatble response a lot above and below the crossover point, so he can sculpt the crossover in certain interesting ways. He will desire a bigger horn for a given cutoff. Those are his reasons and his choices.
I know who your "anonymous expert" is and I know that he has a multi-way system. From memory, I think it's a 4- or 5-way system. He may reduce distortion a bit by using smaller bands for his drivers, but he introduces a lot of distortion by going multiway. Those are his reaons and his choices.
Angelo, it's time that you do experiments and find out what your reasons and choices must be!
Regards and good luck.
Ivo
orphean for 220hz high-pass not too small ?
Angelo,
I built my first horn loudspeaker of my own design in the spring of 1973. It was a terrible honker but marvelous fun. Since then I've owned horn speakers as well as many other types with the ones I think I enjoyed best before Oris being full range electrostatics. I've continued building speakers often using very expensive components. I've heard many horn speakers including the best offerings from JBL, Klipsch, Altec, TaNoy, etc. When I first put together my Oris 150/AER MD3 combinations I realized that I had finally found something very special wonderful and elusive.
Ivo is exactly right when he says that Bert is a master of assembling the best combination of compromises to achieve a great success. And old saying I've always liked is that you can argue with success, but don't expect to win.
You very much remind me of myself when I was a young man.
Don Reid
orphean for 220hz high-pass not too small ?
hi Don
you are mentioning the most important: to have fun. I hope in the end to be able to show up with something that makes a positive difference. Will see.
Angelo
orphean for 220hz high-pass not too small ?
by robmatthew , Wednesday, June 06, 2007, 15:55 (6167 days ago) @ angeloitacare
Hi, Angelo,
Bruce Edgar has also mentioned that the tractix flare begins to drop around an octave above the design frequency. I find the the ORIS 150 exhibits that kind of roll-off in my system. Therefore, I crossover around 250 Hz with my DEQX controlled set-up. Also, I transition to the Fostex 500AX tweeter around 5k. This gives the system a better top end than that produced by a single driver while also substantially broadening the "sweet spot."
With the DEQX, matters of driver integration (phase, delay, amplitude) are solved. The ORIS, when corrected with the DEQX, becomes a truly wonderful music reproducer (it was already pretty wonderful, of course).
Bob
orphean for 220hz high-pass not too small ?
Hi Bob
in my intend, cross a high efficiency 8" Midrange driver at 250Hz in a Oris150 , and use a fostex tweeter above 5khz, should give excellent results. I am figuring out if i will use also a Fostex T500a MKII in my project, ore a RAAL Ribbon tweeter. However , the RAAL has only 102db efficiency. I heard a view people say that passive crossover is better than dsp. I don't know.
rds Angelo
orphean for 220hz high-pass not too small ?
by robmatthew , Wednesday, June 06, 2007, 23:10 (6166 days ago) @ angeloitacare
The Fostex tweeter is really terrific. I have not heard the RAAL but I do have the TAD PT-R9 ribbons in my Supravox system and they are also pretty nice but of much lower sensitivity.
I used to think that passive was better, but after several years of DEQXing I have changed my mind. I have set up many demonstrations that allow the listener to hear both modes on the same system and, without exception, the DEQX version was always preferred by everyone who has heard the system.
Even the ORIS 150 when used full range sounds better to my ears when the signal is conditioned by the DEQX program first. I have been late to accept digital processing but I had to stop fooling myself. My system stays in the digital domain util the power amps.
Bob
Tweak
by PeterSt. , Netherlands, Monday, June 25, 2007, 01:44 (6148 days ago) @ angeloitacare
[img]images/uploaded/image296.jpg[/img]
A little bit offtopic, but since some are eagerly looking for the tweaks, here's one applied.
Now, go find it !
Hehe