CLS said:
I realize that, and I've never really understood why.. other than perhaps the usual 'religion', or because constructing the required circuits is what he's known best for. Other than that, I really don't know. With all the EQ that has to be applied (Q on those XLS woofers is REALLY low!), I don't see the point. Just more complication added to the design. But I suppose if LR's design was too simple, he wouldn't receive all the obvious notice and praise. I mean, I don't see MJK's or anyone else's name being thrown about quite so often? I'm not trying to start anything negative here.. this is something I really don't understand and have never found an objective answer to.
Well, I don't have any solid numbers to back me up, and I have only limited experinces on OB with 8" fullragers and 18" pro woofers.
I guess when both cone area and baffle's area are big enough, the 'problems' with low-Q drivers would probably be much less than we are worrying.
The Qts of my previous experiment of that 8" OB fullranger is about 0.5. And Qts of the later 18" pro driver OB bass is 0.29.
The one with 0.5 Qts seems a 'better' OB driver, but with so little cone area, it's just no comparison to those 2x low-Q 18"er. This is of course not a good example, but you got the idea....
And insterestingly, I found the actual EQ requirements for both cases are very close to the predictions by <the Edge>, which does not take the drivers into consideration.
Just my own little humble observations....
I guess when both cone area and baffle's area are big enough, the 'problems' with low-Q drivers would probably be much less than we are worrying.
The Qts of my previous experiment of that 8" OB fullranger is about 0.5. And Qts of the later 18" pro driver OB bass is 0.29.
The one with 0.5 Qts seems a 'better' OB driver, but with so little cone area, it's just no comparison to those 2x low-Q 18"er. This is of course not a good example, but you got the idea....
And insterestingly, I found the actual EQ requirements for both cases are very close to the predictions by <the Edge>, which does not take the drivers into consideration.
Just my own little humble observations....
Hi BHTX,
I'm with Navin in relation to increased Q.
Increased Q leads to 'one-note' bass, and this was my reason for illustrating the resonance induced Alpha-15 peak which does not arise with the other drivers simulated for comparison.
Increased Qes leads to reduced control of cone motion/ Qms.
The reproduction dynamics are more related to cone dynamics than the driving waveform, hence the need for low cone mass and high VAS for OB working, these being aspects which the DPL-15 does not satisfy. The heavier the cone and the stiffer the overall suspension the more power is necessary for LF OB SPL, unless the cone is allowed to resonate with sustained tones.
A superimposed OB characteristic makes the SPL response of a resonating driver look 'flat', yet its dynamic response simply cannot be flat as well due to that resonance building up in music time.
I wonder if the 'Amazing' drivers had low Qms.
My choice is for 2x Beyma 115-N also simulated (ordered 4 weeks ago and still waiting). In parallel with SS drive these will have the same output as an Alpha-15 at circa 45Hz, yet be 8dB better at 20Hz. Using more Alphas in parallel simply cannot overcome their steep fall in output below 40Hz.
Also EQ can work with a low Q driver that is not 'doing its own thing', whereas EQing a higher Q driver is likely to further muddy reproduction because driver resonance can still be energised by other frequency waveforms - as with finger tapping !
Cheers ......... Graham.
( Hi GM, my oversight - responded to signature - not poster - apologies. )
I'm with Navin in relation to increased Q.
Increased Q leads to 'one-note' bass, and this was my reason for illustrating the resonance induced Alpha-15 peak which does not arise with the other drivers simulated for comparison.
Increased Qes leads to reduced control of cone motion/ Qms.
The reproduction dynamics are more related to cone dynamics than the driving waveform, hence the need for low cone mass and high VAS for OB working, these being aspects which the DPL-15 does not satisfy. The heavier the cone and the stiffer the overall suspension the more power is necessary for LF OB SPL, unless the cone is allowed to resonate with sustained tones.
A superimposed OB characteristic makes the SPL response of a resonating driver look 'flat', yet its dynamic response simply cannot be flat as well due to that resonance building up in music time.
I wonder if the 'Amazing' drivers had low Qms.
My choice is for 2x Beyma 115-N also simulated (ordered 4 weeks ago and still waiting). In parallel with SS drive these will have the same output as an Alpha-15 at circa 45Hz, yet be 8dB better at 20Hz. Using more Alphas in parallel simply cannot overcome their steep fall in output below 40Hz.
Also EQ can work with a low Q driver that is not 'doing its own thing', whereas EQing a higher Q driver is likely to further muddy reproduction because driver resonance can still be energised by other frequency waveforms - as with finger tapping !
Cheers ......... Graham.
( Hi GM, my oversight - responded to signature - not poster - apologies. )
OK many thanks so far,
BHTX I do tend to vacilate, thanx for getting me back on track, when I said I had enough mid-bass it was more a comment on the drivers I have on the shelf to work with; given all the help so far I think I know what to do here to acheive better SPL with-out compression and I know I can't do that with out driver area or biggish boxes.
If the 10 inch drivers I have will work down to around 70Hz in a sealed box my naive assumption was to crossover a little higher than that and fill in the SPL at the bottom end with bigger drivers.
I am still uncertain of the best configuration, 4-way or 3.5 way/ sealed is simpler, easier and I think it sounds a lttle better.
The information youv'e given already has helped a lot.
My current project is 3.5 way open baffle and the el cheapo drivers have very high Q about 1.1 and actually sound quite good, but the point five is a sealed box.
I'm listening to everything said; just a little trouble digesting everything I've swallowed
BHTX I do tend to vacilate, thanx for getting me back on track, when I said I had enough mid-bass it was more a comment on the drivers I have on the shelf to work with; given all the help so far I think I know what to do here to acheive better SPL with-out compression and I know I can't do that with out driver area or biggish boxes.
If the 10 inch drivers I have will work down to around 70Hz in a sealed box my naive assumption was to crossover a little higher than that and fill in the SPL at the bottom end with bigger drivers.
I am still uncertain of the best configuration, 4-way or 3.5 way/ sealed is simpler, easier and I think it sounds a lttle better.
The information youv'e given already has helped a lot.
My current project is 3.5 way open baffle and the el cheapo drivers have very high Q about 1.1 and actually sound quite good, but the point five is a sealed box.
I'm listening to everything said; just a little trouble digesting everything I've swallowed
BHTX said:
WHY??
There's nothing wrong with a small motor on a woofer used on an OB.. IT'S WHAT WORKS! Why make things more difficult? So you can spend more? Look pretty?? I really don't get it..
BHTX, not really.
I think Graham has clearly succinctly explained why in his post above.
Graham Maynard said:
Do you intend to use any electrnoic EQ with the Beyma's? Their Qts is only about 0.3. What is the size of your expected baffle? Any wings?
I was thinking that drives that are designed for lossy boxes (Qts around 0.6-0.7) might be more suitable without the one note bass. Dynaudio used to make some drivers with highist Qts (for Aperiodic boxes).
meanwhile I would love to compare the Augie (15" and 10") against it Exodus (DPL15/10) and Byema (SM115/110) counterparts. The Augies I understand are made by Eminence.
Nordic,
that's funny, I had party this saturday at my house, and as I said before, we had PA speakers I built for music group and behringer 2500 available. After about 3am we started to test the limits of it and one housemate was wearing his kayaking helmet to reduce the sound level.
Otherwise nothing else happened, neither speakers nor amp had any difficulty to cope with high spl. Our ears did. I think we would loose hearing long before anything else.
I had power meter, line of leds diodes, which only go to 100watts, so I have no idea how much we were running it. We never clipped even once!
that's funny, I had party this saturday at my house, and as I said before, we had PA speakers I built for music group and behringer 2500 available. After about 3am we started to test the limits of it and one housemate was wearing his kayaking helmet to reduce the sound level.
Otherwise nothing else happened, neither speakers nor amp had any difficulty to cope with high spl. Our ears did. I think we would loose hearing long before anything else.
I had power meter, line of leds diodes, which only go to 100watts, so I have no idea how much we were running it. We never clipped even once!
Hardly, I've used ~0.16 Qts drivers in OB if you count just tying four 15" HE drivers together with angle iron into a vertical array an OB 
, just the probable reasons why SL prefers to do it his way. I mean it's just good business sense in his case.
Regardless, I didn't get that assertion from his post and don't see how anyone could.
FWIW, I prefer low tuned EBS or BP alignments if multiple driver IB isn't a viable option.
GM
, just the probable reasons why SL prefers to do it his way. I mean it's just good business sense in his case.Regardless, I didn't get that assertion from his post and don't see how anyone could.
FWIW, I prefer low tuned EBS or BP alignments if multiple driver IB isn't a viable option.
GM
Graham Maynard said:
Greets!
No problemo!
True.
Correctomundo.
Agreed.
You just answered your own Q.
So don't be tapping on it while the music's playing!
Anyway, any EQ required would normally be of a shelving variety, so if anything, its perceived in-room performance will theoretically improve.OBs are like any other alignment, you make them to suit the app, so this is moot when the system's properly designed.
Bottom line, both are equally well proven ways to do HIFI quality LF dipoles, though SL's way has much more tuning flexibility. Since Carver drivers are no longer available nor are there any even remotely close spec-wise available, we must make do as best we can if we want to use weak motors or turn strong motors into weak ones either by adding electrical EQ or mass loading with the latter being my preference since I'm in the now ~antiquated, rapidly dwindling 'acoustic solutions for acoustic problems' crowd.
GM
Hi navin,
Yes, and I intend to optimise EQ using this passive LF boost circuit between amp and LS.
Original thread;-
http://www.audiocircle.com/circles/index.php?topic=53322.20
My amp is okay with low impedance load.
Cheers ......... Graham.
Yes, and I intend to optimise EQ using this passive LF boost circuit between amp and LS.
Original thread;-
http://www.audiocircle.com/circles/index.php?topic=53322.20
My amp is okay with low impedance load.
Cheers ......... Graham.
Attachments
BHTX said:
This mirrors my experience with 15" woofers on a too small baffle. Baffle and wing size are going to determine F=, under that point there will be a roll off. The Qts of the driver determines how fast it rolls off. With drivers of about 0.5 Qts, the low end roll off seems to be about 9dB/octave.
My Selenium 15PW3 has a measured Qts of 0.54 and Fs of 33Hz. On my 16.5" (420mm) wide baffle with shallow wings, it rolls off under about 200Hz. So I need to set my plate amp to ~45Hz LP (2nd order) to straighten out the FR. And add a lot of overall gain! But it does work.
You have to overcome the OB losses somehow. This is how I do it.
panomaniac said:
This is a fascinating titbit of information. Thanks. So if we get a driver with a Qts of about 0.8 we can expect a roll of of about 6db/octave. can room placement be used to compensate for such a slow roll off (knowing full well that OBs tend to need 1m of room behind them to breathe)?
panomaniac said:
Fs plays just as big of a role in this as Qts.
As previously stated, as Fs decreases, Qts must also increase to keep a flat response until roll-off (keep in mind that both of these events drop sensitivity). Once again, for an Fs of about 40 Hz, A Qts of 1.2 or so works well for flattest response. Much more below that, and sensitivity starts dropping pretty quickly. Hence.. once again.. Alpha-15's + subwoofers = win.
If you wanted to try to obtain a shallower roll-off.. sure, it's possible.. although not without some sacrifices. EQ will definitely be required in this case.. at which point you just probably screwed up that 0.5 Q you were after...
WAF? lol.. I always laugh at this. Something I'd never allow myself to be in a position to worry about. My fiance knows better than to open her mouth with negative comments regarding my audio habits. Just like I know better than to open my mouth regarding her habits with severe messiness (I'm a perfectionist, she's a complete disgusting mess.. doesn't work so well at times), her buying of clothes and shoes, cooking (for everyone and everything.. and I usually end up cleaning up the big mess), interest in culinary arts (kitchen supplies won't fit in the kitchen, it's ridiculous), and her tendency to put other people she cares about before herself and sometimes before the both of us, etc etc etc. It's been like this since day one, and after 5 years, there hasn't been a major problem yet, and I don't see that changing any time soon. I put up with her ****, she puts up with mine. I think that's fair.
If your wife can't learn to deal with what you enjoy doing most in life, that's another problem in itself.
WAF?? LOL.. sorry, I wouldn't have it.
If your wife can't learn to deal with what you enjoy doing most in life, that's another problem in itself.
WAF?? LOL.. sorry, I wouldn't have it.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.