To be quite frank Alpha 15s suck in comparison to A&D 1524 units, soundwise and pricewice. So in Europe there should not really be any difficulty to choose.
/Erling
/Erling
It is imported by the German firm High Tech HiFi and¨the link is this:
A&D Audio Datenblatt . Currently it is 67 Eur per unit as in this page: HTH AD-Audio bersichtsliste
/Erling
A&D Audio Datenblatt . Currently it is 67 Eur per unit as in this page: HTH AD-Audio bersichtsliste
/Erling
That's for a coverage angle of 90 degrees. A smaller coverage angles means a larger waveguide mouth.
A more accurate formula is:
frequency [Hz] * total coverage angle [degrees] * mouth width [m] = 25400 degrees*m/s
25400 has been determined emperically.
Been eyeing up small Accuton drivers, google doesn't really through up many results of this combo, can a small 6" mate well to a large waveguide?
Is there a technical reason to not use an eliptical wave guide that has the same profile as the OSWG in the horizontal but the vertical profile of say his 10" model? I guess the pessimist would say that limiting the dimensions in the vertical would hurt things so maybe the optimist would look at it as a 10" WG that is stretched in the horizontal. It also addresses the floor and ceiling reflections.
keyser's waveguide cardioid is possible the best implementation of a waveguided speaker that I have ever seen. I just am not sold on the perforated box. I think a standard U-frame would work just as well.
Drawing up plans for my conical horn (ala Bill Woods, OMA) and to improve things I planned to have a turned piece to sit at the throat, to make a smooth transition between the horns exit (matching the angle as best as possible) and 12 sided pyramid.
If I was to then round over the mouth edges, would this be be more of a OSWG, just with faceted sides?
These could eventually be turned round to match, but my lathe can only have 14" diameter over the bed, and haven't tried anything too much bigger, the conical is 27" x 24" which seems a little scary to have spinning around!
If I was to then round over the mouth edges, would this be be more of a OSWG, just with faceted sides?
These could eventually be turned round to match, but my lathe can only have 14" diameter over the bed, and haven't tried anything too much bigger, the conical is 27" x 24" which seems a little scary to have spinning around!
A couple of points:
I have just finished my New Summas which are an update to the originals which I can no longer make. They improved upon a great many things and here is a polar map of the results.
This is the best speaker that I have ever made, but John is right, it is too big. It is too big for me to make in my own shop (although I did do these with great difficulty) and it is too big to ship easily and it is too big for reasonable placement in a room.
Hence, I began to look at what makes the Summa and Abbey great and have concluded that a cut down Summa waveguide (because it works very well) and the 12" woofer in the Abbey would allow me to make a speaker that works as well as the summa but in a package the size of an Abbey. I am going to build one of these when I get a chance. I think that will be a sweet spot.
Regarding a dipole enclosure with an OSWG, I have always thought this might be attractive. So I recently did build a dipole coax speaker. With an active EQ I could make something acceptable (below) but make no mistake about it a coaxial waveguide is not nearly as well controlled as a separate one. The thing that attracted me to the dipole was it gross simplicity to make - just a board with a driver mounted to it. Add some subs and you have a pretty good system. Not a Summa or Abbey, but not even 1/10 the cost.
Well that's my 2 cents.
I have just finished my New Summas which are an update to the originals which I can no longer make. They improved upon a great many things and here is a polar map of the results.
This is the best speaker that I have ever made, but John is right, it is too big. It is too big for me to make in my own shop (although I did do these with great difficulty) and it is too big to ship easily and it is too big for reasonable placement in a room.
Hence, I began to look at what makes the Summa and Abbey great and have concluded that a cut down Summa waveguide (because it works very well) and the 12" woofer in the Abbey would allow me to make a speaker that works as well as the summa but in a package the size of an Abbey. I am going to build one of these when I get a chance. I think that will be a sweet spot.
Regarding a dipole enclosure with an OSWG, I have always thought this might be attractive. So I recently did build a dipole coax speaker. With an active EQ I could make something acceptable (below) but make no mistake about it a coaxial waveguide is not nearly as well controlled as a separate one. The thing that attracted me to the dipole was it gross simplicity to make - just a board with a driver mounted to it. Add some subs and you have a pretty good system. Not a Summa or Abbey, but not even 1/10 the cost.
Well that's my 2 cents.
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What about a Summa/Abbey version with dipole or cardoid woofer?
As you say the waveguide is the best/most important part of your speaker, so why change it to a coax?
Trying to get something at a reasonable price point. My waveguides are pretty expensive to make.
I may yet try a waveguide dipole, and I did do a paper study of a cardioid for the New Summa by adding a second speaker to the bottom, in the stand and using a third active channel. The customer did not want this extra capability because it only added a small increase in directivity below about 500 Hz. Added a lot of cost however.
It's always easy to armchair design a speaker as "do this" or "do that", but in the end, for me it has to be marketable. If you want the ultimate that's a Summa, but it is not for most people.
New Summa
Earl,
Is the oswg on the New Summa essentially the same size as the original?
Sounds like the box is even bigger, though. Different woofer and more low end extension?
Would love to hear more details. The originals were absolutely sublime. Certainly one of the best speakers (especially in throwing a believable image) that I've ever heard.
Bruce
Earl,
Is the oswg on the New Summa essentially the same size as the original?
Sounds like the box is even bigger, though. Different woofer and more low end extension?
Would love to hear more details. The originals were absolutely sublime. Certainly one of the best speakers (especially in throwing a believable image) that I've ever heard.
Bruce
Thanks for the compliments.
Yes, it is the same size, basically exactly the same design, just made differently. The cabinet is a touch smaller than the original, but not much. The drivers are basically neo versions of the originals in order to take some weight out. The New Summa is quite a bit lighter than the original.
The new B&C NBX line of woofers are very impressive. The lower weight got rid of some persistent resonances that were problematic.
The new cabinets use 1 inch poly instead of the 3/4 inch in all the other speakers. The baffle is almost 2" thick and is CLD as is the back. The cross bracing is done as a damped cross member unlike the rigid cross bracing I used in the past. All in all the new enclosure is lighter but much better damped. The lighter drivers means less resonances all around and the extra well damped bracing has reduced all the resonances to nonexistent. There is still a slight dip in the response ( a slight bump in DI) at about 1500 Hz. This is because the woofer narrows too soon. This is why I think that a 12" woofer may be the better choice. But overall the much lower small resonances which occur in all loudspeakers have been effectively removed (as can be seen from the polar map).
Before someone asks, the polar map uses ERB bandwidth smoothing which is frequency dependent to match the bandwidths of our hearing. It is about 1/3 octave at low frequencies to about 1/6 at 1 kHz and about 1/20 at HFs. If there were any resonances you would see them.
Basically this Summa is just using those little tricks that I learned along the way to get that extra dB of precision out of them.
Yes, it is the same size, basically exactly the same design, just made differently. The cabinet is a touch smaller than the original, but not much. The drivers are basically neo versions of the originals in order to take some weight out. The New Summa is quite a bit lighter than the original.
The new B&C NBX line of woofers are very impressive. The lower weight got rid of some persistent resonances that were problematic.
The new cabinets use 1 inch poly instead of the 3/4 inch in all the other speakers. The baffle is almost 2" thick and is CLD as is the back. The cross bracing is done as a damped cross member unlike the rigid cross bracing I used in the past. All in all the new enclosure is lighter but much better damped. The lighter drivers means less resonances all around and the extra well damped bracing has reduced all the resonances to nonexistent. There is still a slight dip in the response ( a slight bump in DI) at about 1500 Hz. This is because the woofer narrows too soon. This is why I think that a 12" woofer may be the better choice. But overall the much lower small resonances which occur in all loudspeakers have been effectively removed (as can be seen from the polar map).
Before someone asks, the polar map uses ERB bandwidth smoothing which is frequency dependent to match the bandwidths of our hearing. It is about 1/3 octave at low frequencies to about 1/6 at 1 kHz and about 1/20 at HFs. If there were any resonances you would see them.
Basically this Summa is just using those little tricks that I learned along the way to get that extra dB of precision out of them.
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Hello Earl,
is this Patent US7270215 - Loudspeaker enclosure with damping material laminated within internal ... - Google Patente a good way to implement the damped cross bracing you mentioned?
Mat
is this Patent US7270215 - Loudspeaker enclosure with damping material laminated within internal ... - Google Patente a good way to implement the damped cross bracing you mentioned?
Mat
Thanks for chiming in Earl, I have a few threads going and this is the most recent idea
http://www.diyaudio.com/forums/multi-way/252310-radian-850pb-wooden-horns.html
I have swayed away from the OB idea for now, with the goal to produce a good sounding bass cabinet, on which my full range teardrops can sit, or the horns I wish to develop, a large JMLC, a large conical and a large-ish OSWG. With my Radian 850pb that should be with me shortly.
If you could make (as I plan to from wood, so cost isn't really an issue) how large would you make a WG. I remember reading that an 18" you said would be optimum.
I considered purchasing a B&C DE250, based on yours and others favourable reviews, but with a driver (Radian 850pb) that is capable of hitting 500HZ, do you think that a larger waveguide 18"-21" may yield better results? Or will there have to be a sacrifice at one end of the scale?
http://www.diyaudio.com/forums/multi-way/252310-radian-850pb-wooden-horns.html
I have swayed away from the OB idea for now, with the goal to produce a good sounding bass cabinet, on which my full range teardrops can sit, or the horns I wish to develop, a large JMLC, a large conical and a large-ish OSWG. With my Radian 850pb that should be with me shortly.
If you could make (as I plan to from wood, so cost isn't really an issue) how large would you make a WG. I remember reading that an 18" you said would be optimum.
I considered purchasing a B&C DE250, based on yours and others favourable reviews, but with a driver (Radian 850pb) that is capable of hitting 500HZ, do you think that a larger waveguide 18"-21" may yield better results? Or will there have to be a sacrifice at one end of the scale?
To get the waveguide and bass driver to match directivity at crossover frequency, the lower the frequency, the bigger the bass driver has to be. i dont know the exact numbers, but i guess you would need a 21 inch or bigger driver for 500hz crossover, since 12inch matches around 1200hz and 15 inch around 1000hz or so. also, being able to hit 500hz doesnt mean that the distortion is acceptable at this frequency.
If theory and practise are correct, as frequency is increased only the inner surface of a cone actively produces sound.
In larger cones ie 15 woofers the dust cap is the predominate radiator.
The polar response of the woofer could be modified as they so with tweeters by placing an absorbant cup or disk near the centre of the cone to control the direct output.
EV do this on some of their systems. ie Assuming the inner active dust cap is fully or partially covered the inner cone will active is a controlled ring radiator.
If anyone else thinks this is a good idea I want the 1st million on the royalties.
Some manufactures use front mounted cooling so I wonder why this has not been thought of before.
In larger cones ie 15 woofers the dust cap is the predominate radiator.
The polar response of the woofer could be modified as they so with tweeters by placing an absorbant cup or disk near the centre of the cone to control the direct output.
EV do this on some of their systems. ie Assuming the inner active dust cap is fully or partially covered the inner cone will active is a controlled ring radiator.
If anyone else thinks this is a good idea I want the 1st million on the royalties.
Some manufactures use front mounted cooling so I wonder why this has not been thought of before.
That's the basic idea, but using three elements is simply to allow a patent. two works just as well.
An 18 " waveguide will just reach down to about 1 kHz. To go down to 500 Hz would require the mouth diameter to double (half the frequency double the radius). A 36" waveguide is going to be hard to make unless you are very well equipped. And then you will certainly need a second one as a waveguide this large will have trouble above about 8 kHz. To me, 18" is optimal because that is the only solution that allows for a single crossover point low enough to not be an issue.
Correct, this is another issue. Going down to 500 Hz for the crossover may sound attractive, but it gets to be impractical when you get into the details.
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