Rudolf said:For measuring the peak you only need to measure the impedance. No microphone necessary, just a multimeter and some sort of tone generator. So there is - almost - no excuse for not doing it yourself.
There is absoutely no need to have any calibration applied.[/B]
Hmm..that way you will certainly get the resonant frequency, but how do you get the acoustic Q and size from the impedance curve? Is it the same as the electrical ? I doubt it, since the speaker itself will also show some impedance variation. Please correct me if I am wrong !
bzfcocon said:
I am looking for a source for those Alpha 15As in Germany. Where did you buy yours?
Thanks, Rudolf
You got me 😀
I no longer live in Germany, but was too lazy to change my avatar. Here in Romania, there's a local Eminence dealer. Should actually be one also in Germany, have you looket at their site ?
I no longer live in Germany, but was too lazy to change my avatar. Here in Romania, there's a local Eminence dealer. Should actually be one also in Germany, have you looket at their site ?
The resonance will not be very symmetrical, so you can´t notch it out perfectly. You could take the acoustic Q from published Ripole diagrams of comparable size and adjust the resistance of the applicable notch filter for a minimised SPL peak on resonance. This is just meant as first aid if you have no access to decent equipment.bzfcocon said:
Sure. They don´t list 15" Alphas at all. Even Google does not show any german source for the 15A. 🙁bzfcocon said:
Weird...the dealer would be:
http://www.adamhall.com/de/AH_K--Em...nence-Alpha__l--de__p--project_2__k--77__f--1
but, as you said, they don't list 15A. Maybe you can call and ask ?
There is a possible reason why Alphas are not always available. As I bought mine, the dealer looked at me and asked if I really want that speaker, as it has a small magnet and is not very powerful.
There is not much use in the pro area for them, except maybe for guitar/bass speakers.
http://www.adamhall.com/de/AH_K--Em...nence-Alpha__l--de__p--project_2__k--77__f--1
but, as you said, they don't list 15A. Maybe you can call and ask ?
There is a possible reason why Alphas are not always available. As I bought mine, the dealer looked at me and asked if I really want that speaker, as it has a small magnet and is not very powerful.
There is not much use in the pro area for them, except maybe for guitar/bass speakers.
Hi,
@euvl. I´m quite short of time in the moment and bzf and rudolf have answered already. For more I suggest PNs
jauu
Calvin
@euvl. I´m quite short of time in the moment and bzf and rudolf have answered already. For more I suggest PNs
jauu
Calvin
Hello Rudolf,
first of all thanks a lot for your investigation about the dipole speakers, unfortunately I don't understand German language (well, I have some difficulties with english, too...
) and I can't appreciate deeply the content of your site.
Have you ever thinked about a translation in English (google translator is really funny, but not completely useful in most cases)?
Some times ago I asked to a german dealer a quote for two Eminence Delta 15", that really inspired me for building a "rude" dipole associated with a Sica full-range.
It seems that they have the item that you need still in the catalog, try a little search here:
http://www.jh-akustik.de/shop/
I hope this will help you.
I need an help, too, but I'm afraid it's a too long story, and it's due to my confusion about the theory of the dipole (but I simply love how it sounds), and I'd don't want to bore DIY members with question probably already treated.
Can I contact you in a pm?
a great hello
first of all thanks a lot for your investigation about the dipole speakers, unfortunately I don't understand German language (well, I have some difficulties with english, too...
) and I can't appreciate deeply the content of your site.Have you ever thinked about a translation in English (google translator is really funny, but not completely useful in most cases)?
Some times ago I asked to a german dealer a quote for two Eminence Delta 15", that really inspired me for building a "rude" dipole associated with a Sica full-range.
It seems that they have the item that you need still in the catalog, try a little search here:
http://www.jh-akustik.de/shop/
I hope this will help you.
I need an help, too, but I'm afraid it's a too long story, and it's due to my confusion about the theory of the dipole (but I simply love how it sounds), and I'd don't want to bore DIY members with question probably already treated.
Can I contact you in a pm?
a great hello
I checked almost all topics about Ripoles on this site, and have several questions. It seems that I missed the simplest thing, I am still not sure, whether the 2 drivers in BMC(BMS) Ripole design are connected parallel in phase (as I think) or out of phase.
Few days ago, I sow an interesting article on
http:mitglied.lycos.de/MundU/audio/dipolsubwoofer.htm?
Dipole (Ripole) with Kef B139. I don’t speak German, but from the text, it seems that this vintage driver is suitable for Ripole. Btw, I have the pair of B139, the oldest model SP6171 and want to try this design.
But, on my Kef B139 version SP6171 fundamental resonance is only 20Hz. According to theory the Ripole design reduces the resonance frequency about 6-7dB or even more and I am wonder that this design could lead me to low freq. that I don’t wont.
Is there any rule for Ripoles (smallest cavities gives deepest fund.res. and opposite) as in this particular case I would like to Fs stays where it is, on 20Hz.
Thanks in advance,
Few days ago, I sow an interesting article on
http:mitglied.lycos.de/MundU/audio/dipolsubwoofer.htm?
Dipole (Ripole) with Kef B139. I don’t speak German, but from the text, it seems that this vintage driver is suitable for Ripole. Btw, I have the pair of B139, the oldest model SP6171 and want to try this design.
But, on my Kef B139 version SP6171 fundamental resonance is only 20Hz. According to theory the Ripole design reduces the resonance frequency about 6-7dB or even more and I am wonder that this design could lead me to low freq. that I don’t wont.
Is there any rule for Ripoles (smallest cavities gives deepest fund.res. and opposite) as in this particular case I would like to Fs stays where it is, on 20Hz.
Thanks in advance,
DAMIC said:
Yes,
the drivers are connected in phase if they are facing each other i.e. cone to cone.
I think the rule of thumb was to have the front chamber area opening = around 1/3 of driver area and the rear chamber area as small as possible . Maybe some of the experts can run simulations for you.
Reducing the cavity size reduces Fs at the expense of efficiency and vice versa.
I think fairly low Qts drivers are preferred for ripoles - the stronger motor is needed to drive the air mass
zobsky said:
Zobsky, thank you very much for reply what confirm my assumptions. As soon as this awfully bad cold weather in my country pass, I will made 4 square MDF boards, two with openings for drivers, and several spacers, different width. The connections would be the simplest with 4 threaded metal rods for easy assembling-disassembling. Starting point should be your rule of thumb with 1/3…. . So, maybe I will find the combination Fs to stay about 20Hz.
I wish if I could contact the guy from mitglied.lycos.de site concerning the dimensions for enclosure concerning B139, but it is a bit complicated due to German language. Any way, I will copy the app. dimensions from the photos.
I just found some more info about Kef B139 SP6171
Weight: 10lb, 4,5 kg flux density10500 oersted, total flux 137000 maxwells. I have not any idea how much it is in new system measurements, but judging to weight it could be sufficient.
Best regards,
🙂
German B139 dipole
Damic - did you build this design. I'm thinking of doing same and would be interested in your opinion.
Damic - did you build this design. I'm thinking of doing same and would be interested in your opinion.
I ran the B139 in a Bailey TL..
it was ok but ran out of gas sooner than I would have liked. With dipole bass the two key elements are Sd and Xmax. The B139 does not have much in either department so it will not take much eq. If you wanted to experiment with the B139 you could try a TAP horn. I think that someone worked out a design for a B139 based TAP at the Colaberative Tapped Horn Project see this link http://www.diyaudio.com/forums/showthread.php?s=&threadid=97674
it was ok but ran out of gas sooner than I would have liked. With dipole bass the two key elements are Sd and Xmax. The B139 does not have much in either department so it will not take much eq. If you wanted to experiment with the B139 you could try a TAP horn. I think that someone worked out a design for a B139 based TAP at the Colaberative Tapped Horn Project see this link http://www.diyaudio.com/forums/showthread.php?s=&threadid=97674
Hi mmaudio,
Two weeks ago, I spent few afternoons and made ripol with two Kef B139.
Actually I used the photos from link:
http://www.tech-diy.com/Dipol-Subwoofer.pdf
where are shown cross sections of the sub and copied the dimensions.
The enslosure is made by venered 20mm high density chipboard, the material I already have. All sides are glued and secured with several screws. The design looks almost the same as on the photos from a.m. link.
Now, what about sound? Well, the sound is realy very nice, as other diyers reports on various sites. I used the electronic x-over at 80Hz, 24dB/LR and fed the combination with separate amp. My main speakers are hybrids, Apogee Centaur Minor, 26inch ribbon working in dipol and 6,5 inch Audax mid-woofer in modified DBR enclosure.
All my friends are pleased with sound. On low volume, the sound is fantastic but there are problems on the medium and higher volumes. The fact is that mine B139 version SP6171 is the one made at late 60's or beganing of 70's and the power handling is very low, about 25-30 watt only. The older forum members probably remember the first B139 version with wide alloy casted frame/basket.
As said, on the low power, sub works very nice but since the volume is increased the speakers run in clipping. I beleive that the project from german link works better, as later version of Kef B139 were made upto 100watt handling power.
I dont have any special measuring equipment, but playing the test CD I visualy noticed that membrane starts to move from 10Hz.
What else, I like is the compactness of the design. Mine enclosure is about 34 liter, for two drivers. Just to say that Vas for B139 goes upto 160 liter, it meens that in this design you can go nearly 10 times down comparing to BR design what sometimes can be a great benefit.
The only negative side I see is of course, reduced eficiency of the system, between 6 to 7 dB per driver, as other reports.
The whole project was the trial one and this sub is not actually usable in my present sistem due to problem with limited power handling, but I am glad that there is realy a great potential in ripole design. Personaly, it cost me nothing as I had all components as a surplus and making it was a great fun for me. We comes again to known fact that use of cheap, high sensitivity, high Qtc PA drivers like Eminence 15 Alfa could be maybe the best way for ripole.
Regards,
p.s. I forgot to mention that integration with main speakers is superb. BTW for years, I could not manage to integrate properly my amplified Mission 73AS sub. Could be due to radiation pattern.
Two weeks ago, I spent few afternoons and made ripol with two Kef B139.
Actually I used the photos from link:
http://www.tech-diy.com/Dipol-Subwoofer.pdf
where are shown cross sections of the sub and copied the dimensions.
The enslosure is made by venered 20mm high density chipboard, the material I already have. All sides are glued and secured with several screws. The design looks almost the same as on the photos from a.m. link.
Now, what about sound? Well, the sound is realy very nice, as other diyers reports on various sites. I used the electronic x-over at 80Hz, 24dB/LR and fed the combination with separate amp. My main speakers are hybrids, Apogee Centaur Minor, 26inch ribbon working in dipol and 6,5 inch Audax mid-woofer in modified DBR enclosure.
All my friends are pleased with sound. On low volume, the sound is fantastic but there are problems on the medium and higher volumes. The fact is that mine B139 version SP6171 is the one made at late 60's or beganing of 70's and the power handling is very low, about 25-30 watt only. The older forum members probably remember the first B139 version with wide alloy casted frame/basket.
As said, on the low power, sub works very nice but since the volume is increased the speakers run in clipping. I beleive that the project from german link works better, as later version of Kef B139 were made upto 100watt handling power.
I dont have any special measuring equipment, but playing the test CD I visualy noticed that membrane starts to move from 10Hz.
What else, I like is the compactness of the design. Mine enclosure is about 34 liter, for two drivers. Just to say that Vas for B139 goes upto 160 liter, it meens that in this design you can go nearly 10 times down comparing to BR design what sometimes can be a great benefit.
The only negative side I see is of course, reduced eficiency of the system, between 6 to 7 dB per driver, as other reports.
The whole project was the trial one and this sub is not actually usable in my present sistem due to problem with limited power handling, but I am glad that there is realy a great potential in ripole design. Personaly, it cost me nothing as I had all components as a surplus and making it was a great fun for me. We comes again to known fact that use of cheap, high sensitivity, high Qtc PA drivers like Eminence 15 Alfa could be maybe the best way for ripole.
Regards,
p.s. I forgot to mention that integration with main speakers is superb. BTW for years, I could not manage to integrate properly my amplified Mission 73AS sub. Could be due to radiation pattern.
Size and stroke....
you could probably get some fair change for your B139's on the used market. Why not consider two pairs of Peerless SLS12 drivers. Or for not a lot more you could use 15 or 18 inch Eminence drivers for some serious area and output down low.
you could probably get some fair change for your B139's on the used market. Why not consider two pairs of Peerless SLS12 drivers. Or for not a lot more you could use 15 or 18 inch Eminence drivers for some serious area and output down low.
Hi moray james
Yes, I am considering to try another project with bigger and more sensitive drivers. Perless are not on the market in my area but Eminence 15 Alphas are available in Belgrade for about 50 Euros/pc. Btw, my best man are so pleased with sound and want invest money in 2 pairs of Alphas, of course I will assist him in making of the enclosure.😉
Best regards
Yes, I am considering to try another project with bigger and more sensitive drivers. Perless are not on the market in my area but Eminence 15 Alphas are available in Belgrade for about 50 Euros/pc. Btw, my best man are so pleased with sound and want invest money in 2 pairs of Alphas, of course I will assist him in making of the enclosure.😉
Best regards
Re: Size and stroke....
I got $100 for the last pair of racetrack B139 that i sold...
daVE
moray james said:
I got $100 for the last pair of racetrack B139 that i sold...
daVE
I thought that high Qts drivers (such as the alpha 15) were NOT ideal for ripole OBs . Be careful.DAMIC said:
Hi zobsky,
You are probably right, but I consider ripole/dipole as very similar designs and have in mind Martin J.King last study:
Designing a passive two way open baffle speaker system, where on the page 15 he said that his recommendation is to use woofer drivers that are at least 6 do 10 or more dB efficient than the rest of the speaker system and Qts values to be between 1 and 1,2.
This is the reason, I think Eminence 15 Alphas could maybe good for ripole.
Regards
You are probably right, but I consider ripole/dipole as very similar designs and have in mind Martin J.King last study:
Designing a passive two way open baffle speaker system, where on the page 15 he said that his recommendation is to use woofer drivers that are at least 6 do 10 or more dB efficient than the rest of the speaker system and Qts values to be between 1 and 1,2.
This is the reason, I think Eminence 15 Alphas could maybe good for ripole.
Regards
No harn in trying...
you can have a listen and see. Remember the Ripole will lower the driver resonance buy a fair amount. If things do not work with the high Qt drivers then you can be sure to obtain excellent results with the Delta or Kilomax. It will cost you your time to sell the drivers that are not wanted and what ever loss you take for them being sold as used.
you can have a listen and see. Remember the Ripole will lower the driver resonance buy a fair amount. If things do not work with the high Qt drivers then you can be sure to obtain excellent results with the Delta or Kilomax. It will cost you your time to sell the drivers that are not wanted and what ever loss you take for them being sold as used.
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