Magnetar said:
I am inspired by your creation on WMTMW which was documented here. I will briefly described what I want to do,
the configuration similar to yours which a few variations,
1. Use compression driver instead of Heil tweeter you are using.
2. Mid-range which I cannot determine at the moment, that is why my question to you.
type of music I listen and like, Jazz, vocal and some popular music. I am after some dynamics which you are getting. NOT head banging rock, metallic or music with plenty of bass effects.
3. Woofer(used in open baffle like yours) 15in is sufficient, most people seems to favour high Qts like eminence alpha 15a and possibly beta15a. any other suggestions.
You have lots of practical experience and your opinion is valued.
Hello again, the Audax PR170 or the RCF LS800 (will go lower but not as high as the Audax plus handle more power)if you don't want to spend a lot of money - The JBL 2123's are more sensitive then both, won't go as low as the RCF, handle a bit more power, but won't go so high in an MTM - 2K is ok The JBL is probably best as a single mid or MMT
Best compromise is the RCF LS800 IMO
PS- I ended up switching the Heil out for a Beyma 380 driver in the little 18 sound horn and liked it better.
Best compromise is the RCF LS800 IMO
PS- I ended up switching the Heil out for a Beyma 380 driver in the little 18 sound horn and liked it better.
Hello Magnetar,
I hope my post about the AER drivers in the Beyond Ariel thread was not the cause for your decision to stop posting there.
Regarding this killer sistem of yours, did you tried the alnico JBL midrange afterall? And do you have a pic of the sistem from lateral? I'd like to have an idea about the size of the midrange horn...
Keep up the excelent work!
I hope my post about the AER drivers in the Beyond Ariel thread was not the cause for your decision to stop posting there.
Regarding this killer sistem of yours, did you tried the alnico JBL midrange afterall? And do you have a pic of the sistem from lateral? I'd like to have an idea about the size of the midrange horn...
Keep up the excelent work!
SunRa said:
No, not at all! I just got tired of discussing someone else's fantasy! Plus nobody really seemed to give that much credit on my advice so let them build there own speaker.I just assume let you all give your best and come up with something fresh. When it's all done maybe I'll learn something? When it's reality as in built and being enjoyed, not just a discussion, I will come probably back and talk..
The JBL was more extended in the treble but was compressed when pushed a bit. I like the B&C better.
SunRa said:
Virtually all bass/ front cone driven horns have a smaller throat than the radiating area of the driver. I mount it to the throat!
The actual throat of a compression driver is tiny, and has 3-5 slots that are called phase plugs. You can build a phase plug for a cone too (the dome or diaphragm in the compression driver is much like a convex cone) if you want better high frequency response and higher sensitivity in the top end.
Magnetar said:
Hi Magnetar,
Just want to have you idea about the BEYMA SMC-1050. It has titanium dome and surround but with Mylar diaphragm. Looks like it has the best of both world?? it is also a bit cheaper than the CP380.
http://www.usspeaker.com/beyma SMC1050-1.htm
Like ttan98, I am keen to use PR170M0 as mid.
Thanks
SamL said:
Hi Magnetar,
Just want to have you idea about the BEYMA SMC-1050. It has titanium dome and surround but with Mylar diaphragm. Looks like it has the best of both world?? it is also a bit cheaper than the CP380.
http://www.usspeaker.com/beyma SMC1050-1.htm
Like ttan98, I am keen to use PR170M0 as mid.
Thanks
Hello, can you get B&C drivers where you live?
The edge or surround on that is titanium. It will give a harder sound still since that is the critical part of the diaphragm. With the little Audax you can crossover pretty high - I don't think you have to spend that much money to get great results
Well, we can't get any decent driver from down under. Have to import all of them. A pair of 15" will cost around US$150 on freight. 
You lot in US are SO lucky
Back to the PR170M0 well, I like wide open sounding as I don't site in the sweet sport & listen like most people. With that I thinking of crossing the Audax around 2.5KHz or maybe lower. Hope this is not 'over the top'. Music type are vocal, jazz and popular music. Don't need high SPL and will be happy with sensitivity above 93db. Room is small, about 18ft x 30ft x 8.5ft.
Sam
You lot in US are SO lucky
Back to the PR170M0 well, I like wide open sounding as I don't site in the sweet sport & listen like most people. With that I thinking of crossing the Audax around 2.5KHz or maybe lower. Hope this is not 'over the top'. Music type are vocal, jazz and popular music. Don't need high SPL and will be happy with sensitivity above 93db. Room is small, about 18ft x 30ft x 8.5ft.
Sam
SamL said:Well, we can't get any decent driver from down under. Have to import all of them. A pair of 15" will cost around US$150 on freight.
You lot in US are SO lucky
Back to the PR170M0 well, I like wide open sounding as I don't site in the sweet sport & listen like most people. With that I thinking of crossing the Audax around 2.5KHz or maybe lower. Hope this is not 'over the top'. Music type are vocal, jazz and popular music. Don't need high SPL and will be happy with sensitivity above 93db. Room is small, about 18ft x 30ft x 8.5ft.
Sam
I see why it is so important to get good advice and not pay shipping for drivers 'to try' that aren't what you want! Shipping is crazy..
I have used the audax way up -even no low pass and just a super tweeter 6k up, and it was still OK to move about and great sound. Being on an open baffle helps this aspect quite a bit. I think you will like the DE10 and the 18 sound horn, if you want to open up the sweet spot more put a super tweeter on the back panel (or use two de10!) , that is a nice size room, I think you will be happy with the 18 sound dispersion and lack of 'honk' or coloration. It is really a great horn even when compared to ultra expensive stuff. If you crossover at 3.5k I think you'll be fine with the open baffle PR170MO/DE10/18 sound horn
I have seen B&C makes a horn designed for the DE10, it may be a good option too based on the dispersion graphs and it's aspect seen in it's data sheet. I have no experience with it though
Hi Magnetar,
I hope I am not bugging you too much! Mr. Geddes expressed several times his findings that the transition between the exit of the compression driver and the throat of the horn must be as smooth as possible in order to avoid difraction and high order modes.
This means not only that the diameters of driver's exit and horn throat must coincide but also that the angle must be the same in order to provide the smooth transition.
With cones the problem is somehow different I guess (I have no experience with cones in horns) in that there is no angle to match.
So actualy my question is how much of the cone is obturated by the throat of the horn, if any? I've always thought that the throat must fit precisely on the rubber/cardboard ring around the folded suspension.
I hope I am not bugging you too much! Mr. Geddes expressed several times his findings that the transition between the exit of the compression driver and the throat of the horn must be as smooth as possible in order to avoid difraction and high order modes.
This means not only that the diameters of driver's exit and horn throat must coincide but also that the angle must be the same in order to provide the smooth transition.
With cones the problem is somehow different I guess (I have no experience with cones in horns) in that there is no angle to match.
So actualy my question is how much of the cone is obturated by the throat of the horn, if any? I've always thought that the throat must fit precisely on the rubber/cardboard ring around the folded suspension.
ttan98 said:
Hello
The XT120, the horn used at the beginning of this thread
SunRa said:
The diaphragms of a compression driver and it's phase plug are an integral part as well as the short conical horn in front of it called the exit. They are all designed together and are designed to be used with a specific diameter horn throat. I agree that transition is supposed to be as close to perfect as possible. Problem is the exit is typically 200-300 hz conical flare and the horn is different. This is true of Geddes horn too, so it is not a perfect transition. The phase plug has MASSIVE diffraction and are tiny little slits bending and compressing and altering the direct sound coming off the diaphragm. All of this means there is no such thing as a direct radiated compression driver, they are all altered dramatically. Now in his experiments he found he can use a bandaid called a foam insert or plug to lower what he calls HOMs. These HOMs from what I understand are caused by the compression of air in the throat of system. in other words the phase plug, the exit and the beginnining of the mouth of the horn. I do not have access to his white paper and I'm sure it can be explained better by him (he is the only manufacture I know that calls this 'HOM') - ALL horns will have this build up of standing waves at the throat. His horn tweeter system still does but he chose to attenuate the output of the system with a 'selective' filter - the open cell foam. Another alteration of the 'direct' sound..!
If you look at most midrange horns and all bass horns you will find the throat diameter is smaller than the cones radiation diameter. This brings up efficiency and in some cases gives you better response on the top end )higher frequency) of the horn. It also acts as a low pass filter to attenuate the out of band response. Shaping the size and shape of this area surely has a big or small influence on the sound. Some horn designers will intenionally take advantage of this by shapng the response of the cone/ throat/ horn to get the results they want to acheive. To attenuate the out of band response with a horn throat makes the crossover much easier ( the response dies off quickly!) and lowers harmonic distortion.. Take a look at the Avntegarde Horns and their white paper. Cone driven horns for more information -
A horn can sound SPECTACULAR and real, or can sound like a cheap megaphone! It is both science and art to get spectacular results. There is much more to this than I writing here but I have an appointment and have to run. I wull come back later-http://avantgarde-usa.com/technology.html
I found what could be the source of my previous conception regarding the diameter of the (cone) driver equals the throat of the horn. Here is the link to Mr.'s Bert Doppenberg article. (the page does not support internal links so go to Articles to read, Front Horn Design)
Here is the quote that matters:
The throath needs to have the same diameter as the conus surface. In this case Ah became 256cm²
From reading the link to avantgarde acoustics, it seems to me that the use of compression chambers with a cone driver is for a) increasing spl, b) minimizing cone movement and related distorsions by a proper cone loading and c) creating a low pass filter.
Do you have any further materials on compression chamber design? It would be an interesting lecture...
Here is the quote that matters:
The throath needs to have the same diameter as the conus surface. In this case Ah became 256cm²
From reading the link to avantgarde acoustics, it seems to me that the use of compression chambers with a cone driver is for a) increasing spl, b) minimizing cone movement and related distorsions by a proper cone loading and c) creating a low pass filter.
Do you have any further materials on compression chamber design? It would be an interesting lecture...
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