I did read the John Whittaker study (was it done around 1997 ?), and the drivers they had there measured very different from my own, which are about 2 years old now. I suspect B&G has made design changes.
They sure did change the Neo3, because early examples were several dB down at 20 kHz, and the new ones are not.
They sure did change the Neo3, because early examples were several dB down at 20 kHz, and the new ones are not.
The "beaming" above ~8 khz is why I added the extra drivers... and shows in my off-axis plots... the power response in the room improved as well
I read all the alsr postings from Blondia & Whittaker as well... very helpful in the design. not sure the airfoil has all that great effect on the actual response (but it's sure pretty!) as mine are easily equalized flat to +-2 dB or so from maybe 500 to 15K... but I like the current downward tilt better...
part of why I'm thinking of redoing mine in clear Lucite... time for some cosmetic changes I guess...
John L.
I read all the alsr postings from Blondia & Whittaker as well... very helpful in the design. not sure the airfoil has all that great effect on the actual response (but it's sure pretty!) as mine are easily equalized flat to +-2 dB or so from maybe 500 to 15K... but I like the current downward tilt better...
part of why I'm thinking of redoing mine in clear Lucite... time for some cosmetic changes I guess...
John L.
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As I remember it the airfoil shape allegedly flattens out the frequency response because the phase cancellation (front to back of the dipole) is not concentrated at one frequency. However that totally looks by the affects of the 'missing baffle' that is on the inside edge of the cabinets, so I dunno ...
In any case, you are right they do look cool! I wonder why RD-75s aren't more popular? They never seemed to catch on in the DIY community. Is it their size that discourages people?
In any case, you are right they do look cool! I wonder why RD-75s aren't more popular? They never seemed to catch on in the DIY community. Is it their size that discourages people?
I believe the offset position from center vertical and the slant sides help eliminate some of the dipole ripple as the front/rear cancellation is spread over many frequencies. I swept back the baffle to lower the knee and slanted the baffle some (but I wanted to keep the width at ~20" or so...
Size does seem to matter
... spousal acceptance is a BIG deal for some (mine doesn't really care... hence living room more of a man cave)
plus last ten years, I think ipods, etc. have ruined most people's hearing anyway
John L.
Size does seem to matter
... spousal acceptance is a BIG deal for some (mine doesn't really care... hence living room more of a man cave)plus last ten years, I think ipods, etc. have ruined most people's hearing anyway
John L.
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Size does seem to matter
My wife almost started to cry when I explained her the size of what eventuelly did not become our new livingroom speakers.....
Luckily, I have my own dedicated batcave where no females are allowed entry.
A few more questions.
I have a few more questions if you don't mind answering me. By the way thanks for the reply Stig. I've been looking at the RD75 for a few years now but have been resistant to order because I like tube amps. I have a 15 watt transcendent sound otl amplifier that I really enjoy and was hoping maybe it would be enough to run the RD75's. Would 15 watts per channel be enough power. My room is 14 feet wide by 16 feet long. I have a active crossover with 48db slopes that I would use at 175hz to crossover with the woofers. I don't listen ridiculously loud. Usually around 95-98db peak and average of 90db. Also what is the lowest impedance the driver gets down to. Is it pretty much a flat 6 ohms across the frequency range?. Thanks for the help
I have a few more questions if you don't mind answering me. By the way thanks for the reply Stig. I've been looking at the RD75 for a few years now but have been resistant to order because I like tube amps. I have a 15 watt transcendent sound otl amplifier that I really enjoy and was hoping maybe it would be enough to run the RD75's. Would 15 watts per channel be enough power. My room is 14 feet wide by 16 feet long. I have a active crossover with 48db slopes that I would use at 175hz to crossover with the woofers. I don't listen ridiculously loud. Usually around 95-98db peak and average of 90db. Also what is the lowest impedance the driver gets down to. Is it pretty much a flat 6 ohms across the frequency range?. Thanks for the help
Is there anyone that can answer my questions.
I was hoping a fellow member could help answer the few questions I posted. I would really like to order a pair of BG RD75 but it is important I know the answers to my previous questions. StigErik you have a lot of knowledge on these drivers and would really appreciate your help if you have the time. Thanks guys.
I was hoping a fellow member could help answer the few questions I posted. I would really like to order a pair of BG RD75 but it is important I know the answers to my previous questions. StigErik you have a lot of knowledge on these drivers and would really appreciate your help if you have the time. Thanks guys.
I have a few more questions if you don't mind answering me. By the way thanks for the reply Stig. I've been looking at the RD75 for a few years now but have been resistant to order because I like tube amps. I have a 15 watt transcendent sound otl amplifier that I really enjoy and was hoping maybe it would be enough to run the RD75's. Would 15 watts per channel be enough power. My room is 14 feet wide by 16 feet long. I have a active crossover with 48db slopes that I would use at 175hz to crossover with the woofers. I don't listen ridiculously loud. Usually around 95-98db peak and average of 90db. Also what is the lowest impedance the driver gets down to. Is it pretty much a flat 6 ohms across the frequency range?. Thanks for the help
15 watts should be enough, but it all depends....
90 dB average is quite loud, and depending on the dynamic range of the music and your listening distance you might need up to 100 watts or more. The RD-75's are not very efficient speakers.
Impedance is 6 ohms flat from 20 to 20k.
Thanks for the help. I guess I'll just have to order them and see if I have enough power. I was mistaken when I said I listen at a average of 90db. I measured the volume at the listening chair and average is 84-86 with peaks of 93 sometimes but rarely. What width of baffle do you recommend if I want to crossover at 175hz without having to eq. I figured around 21 inches, does that sound correct?. Again thanks for all the help.
The point is that the frequency response changes with distance. Since the RD-75 is not a true line-source below 1 kHz, the level below 1 kHz or so will roll off slightly the farther from the driver you get.
With 10 feet distance, I recommend a fairly large baffle, around 50 cm (~20 inches) total width. This should make the FR fairly flat 10 feet away.
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