I'm thinking of a 2-way dipole line-array using the B&G RD75 ribbon and a stack of woofers of some kind. There well be no baffle, just nude drivers suspended from the ceiling or a tall frame.
I've never seen or heard the RD75, so any comments would be nice before I go and order them... 🙂
As I understand, the RD75 is dipole / open backed. It should be possible to run it well below 1 kHz even as dipole, even thought it will roll off somewhat.
With XO below 1 kHz, using 10" woofers and still keep the dipole peak above XO is possible, and with enough drivers there should be plenty of bass as well. The RD 75 is approx 1,9 meters tall. Eight 10" woofers would match well in terms of total height of the speaker.
Okay, what do you think if this?
I've never seen or heard the RD75, so any comments would be nice before I go and order them... 🙂
As I understand, the RD75 is dipole / open backed. It should be possible to run it well below 1 kHz even as dipole, even thought it will roll off somewhat.
With XO below 1 kHz, using 10" woofers and still keep the dipole peak above XO is possible, and with enough drivers there should be plenty of bass as well. The RD 75 is approx 1,9 meters tall. Eight 10" woofers would match well in terms of total height of the speaker.
Okay, what do you think if this?
A sketch of the idea:
An externally hosted image should be here but it was not working when we last tested it.
There are a couple of people on the HTGuide DIY forum who've been using something similar for several years now.
HTGuide Forum - BG RD75 for line array
HTGuide Forum - New Home for the BG Ribbons - Part 27
Try a search on that forum, there are probably other threads that might be relevant.
HTGuide Forum - BG RD75 for line array
HTGuide Forum - New Home for the BG Ribbons - Part 27
Try a search on that forum, there are probably other threads that might be relevant.
As Saurav said, go check out HTguide. I am one of the guys who is currently running 12 Peerless 6 12" woofers, B&G Neo8's, and B&G Neo3's for a 3 way dipole line array. It stands 7 feet tall by ~24 inches wide. Custom electronic crossover with crossover points at 40 Hz (to subs), 800 Hz (woofer to mid), 4 KHz (Mid to tweet). Lots and lots of dynamic range, very clear, and very precise in the reproduction of music.
Chuck
Chuck
Nice projects, but not designed for Constant Directivity with those very wide baffles. My idea is to run the drivers without baffle. Havent found anyone doing that with the RD75.
Last edited:
This diy ribbon might be an interesting alternative to the rd75?
Byggbeskrivning för den neodymiumbestyckade band
(sorry, article in Swedish but you can perhaps translate with google)
Used in these speakers, not baffle-less but said to be very, very good.
Byggbeskrivning för den neodymiumbestyckade band
(sorry, article in Swedish but you can perhaps translate with google)
Used in these speakers, not baffle-less but said to be very, very good.
An externally hosted image should be here but it was not working when we last tested it.
I've thought about someting similar myself, but a little less tall design with those diy ribbons mentioned above. I'm not sure you really need something 2m tall to make an efficient linesource? But you seem to be used to so much more spl capacity so you might need it for shear cone area...
Coupled with tapped horn subs or your giant 21" h-baffles for the lowest octave I'd think this would make a killer system I think.
For 10" mids I've thougt about Beymas 10g40 and 10mw/Nd (more open rear structure might be good) or Eminence BASSLITE CH2010 (hempcone, small neo magnet)
Suppose one of the Seas excel 10" woofers might be useful too but I hav'nt tried simuating those, low sensitivity IIRC...
Best regards,
Niklas
Coupled with tapped horn subs or your giant 21" h-baffles for the lowest octave I'd think this would make a killer system I think.
For 10" mids I've thougt about Beymas 10g40 and 10mw/Nd (more open rear structure might be good) or Eminence BASSLITE CH2010 (hempcone, small neo magnet)
Suppose one of the Seas excel 10" woofers might be useful too but I hav'nt tried simuating those, low sensitivity IIRC...
Best regards,
Niklas
Being Norwegian, I can read swedish perfectly.... 🙂
Making my own ribbon is a little bit out of scope right now, but its interesting to give it a try sometimes. Being a bit lazy, I think I'll stay with off the shelf drivers to begin with... therefore the RD75.
I'm thinking good paper woofers for this, Excels are just too damn expensive. Very open rear structure is necessary, ruling out the otherwise good Beyma's. Something with small magnets (Neodymium) and very open basket is fine.
Making my own ribbon is a little bit out of scope right now, but its interesting to give it a try sometimes. Being a bit lazy, I think I'll stay with off the shelf drivers to begin with... therefore the RD75.
I'm thinking good paper woofers for this, Excels are just too damn expensive. Very open rear structure is necessary, ruling out the otherwise good Beyma's. Something with small magnets (Neodymium) and very open basket is fine.
Last edited:
An RD75 no baffle line array is a back burner idea I've been kicking around. From the HTGuide threads the cross could be 500Hz or lower. So I'm unsure there's a hard requirement for a small magnet/very open back---with most woofers the problem for the back wave is the spider and the magnet's kind of incidental. A woofer with a vented pole piece might be a better choice. mige0's observations on low Rms seem particularly apropos here due to the magnetostat integration and low power per woofer in a line array, but low Rms, low Fs drivers are hard to find. They're eight inches, but the Beyma 8BR40 and Peerless 830667 and 830869 are ones I've had in mind. Haven't actually spotted any ten inchers that look as attractive as the 830667 (I'd cross LR6 so I'm not too worried about the diffraction dip at 900Hz). There are some interesting twelves, but that starts to get a bit bigger than I'd like for the frequencies I have the impression the RD75 would be happiest crossing at.
The rule of thumb I've been going by is Fs on the lowest woofer should be about where one's willing to accept roll off in the bass. Which, for me, means 30Hz or so. Though I've a hunch Stig Erik plans to use subs to handle the very low bass, in which case there's more flexibility on the woofer Fs.
Have a look at the spider diameter too. A small spider will help to keep the resonating volume between cone and basket small. Rms will probably go up because the small spider has to be stiffer, but I would call that a minor problem. Venting of the area behind the spider would be nice, but not mandatory IMHO.
Rudolf
Attachments
Here's a quite interesting experiment with the RD75. It seems that the bare driver can go quite low by itself. There's some nasty things at 2.5 kHz though...
ALSR - The RD75 Dipole Baffle Study - The Auditorium Measurements
ALSR - The RD75 Dipole Baffle Study - The Auditorium Measurements
My Neo3s do something similar at 3.2kHz. Interestingly, THD stays flat through the SPL bobble and phase doesn't wiggle any more than usual. I don't hear any problems around 3.2kHz, but there's enough other limitations in the system issues could well be masked.
Things are moving a bit forward here. A pair of B&G RD-75 has been ordered! 🙂
Haven't settled on which woofers to use yet, but the plan is to use eight 10" woofers. The Seas L26RFX/P is at the top of the list for the moment.
Haven't settled on which woofers to use yet, but the plan is to use eight 10" woofers. The Seas L26RFX/P is at the top of the list for the moment.
Hi StigErik,
broad smile from my side 😀
Hopefully the suspension will not be too soft with 1.2mm/N unless you plan for a HP anyway.
Oliver
broad smile from my side 😀
Hopefully the suspension will not be too soft with 1.2mm/N unless you plan for a HP anyway.
Oliver
I have an option for keeping my closed box subs in case there's not enough low bass, and yes - some kind of HP on the woofers would be a good idea anyhow.
Hi all..
Member RUDOLF posted a link in a german DIY-forum about your ballfe-less baffle projects here at DIY-Audio. So I digged out a project, that I reflected on in the past.. -- but I never realized it..
So I carried together all the material I collected for this project, and started mounting it. Please see pictures, how I realized some construction-details.. (used speakers are vintage german widerange tube-radio-speakers of the size 20x31 cm, and a heil air motion transformer in the center. Cut-off-frequency will be ~ 1.5 kHz. )
Best regards,
Andreas
Member RUDOLF posted a link in a german DIY-forum about your ballfe-less baffle projects here at DIY-Audio. So I digged out a project, that I reflected on in the past.. -- but I never realized it..
So I carried together all the material I collected for this project, and started mounting it. Please see pictures, how I realized some construction-details.. (used speakers are vintage german widerange tube-radio-speakers of the size 20x31 cm, and a heil air motion transformer in the center. Cut-off-frequency will be ~ 1.5 kHz. )
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Best regards,
Andreas
Updates:
The RD75 drivers have arrived! They are big!! 🙂 Hooked them up just to test if they worked, and they do... Initial thoughts on the sound quality is that they sound very much like "nothing" - apparently very low coloration.
Woofers will be Seas L26RFX/P, and they are ordered as well, I hope they arrive in a week or so.
I'm having an early summer holiday, so there's not going to happen much more until july the earliest.
The RD75 drivers have arrived! They are big!! 🙂 Hooked them up just to test if they worked, and they do... Initial thoughts on the sound quality is that they sound very much like "nothing" - apparently very low coloration.
Woofers will be Seas L26RFX/P, and they are ordered as well, I hope they arrive in a week or so.
I'm having an early summer holiday, so there's not going to happen much more until july the earliest.
- Status
- Not open for further replies.