Thanks panomaniac,
I've tried a PLLXO on a bass amp. (ok, it was a pllxo with input and output buffers, which allowed me to precisely calculate the -3db point, regardless of the amp input). It was a 1st order low pass. I've played with different values, going from 60 to 200 Hz. There was bass; and the bass issue was not bothering me so much as the mids that were still being heard coming out the Betas. (Even at the lowest crossover point)
Visaton was high-passed from starting from fullrange to maybe 350 Hz.
I concluded that I like the sound of Visaton (including bass when run fullrange-but couldn't push it hard). So, I wanted to run the Visaton as low as possible, and just introduce the bass helper at the lowest octaves.
That's how I ended with the following setup:
1. Visaton high-passed (PLLXO), first order at 80 Hz
2. Eminence: 2nd order active at 60 Hz + a 3.3 mH inductor between a bass amp and the Eminence. (so that would be active/passive combination). This tamed some upper muddiness that was present when only 1st order low pass was running.
Actually it seems that inductor does not make a big difference, but somehow it sounds better when it's in the circuit (maybe it's just raising the Q of the Betas or introducing a phase shift)
Overall, it does not sound that bad. I like this setup more than when the Visatons and the Eminences are crossed higher (like 250 hz, what is mostly suggested) ...
Regards,
Vix
I've tried a PLLXO on a bass amp. (ok, it was a pllxo with input and output buffers, which allowed me to precisely calculate the -3db point, regardless of the amp input). It was a 1st order low pass. I've played with different values, going from 60 to 200 Hz. There was bass; and the bass issue was not bothering me so much as the mids that were still being heard coming out the Betas. (Even at the lowest crossover point)
Visaton was high-passed from starting from fullrange to maybe 350 Hz.
I concluded that I like the sound of Visaton (including bass when run fullrange-but couldn't push it hard). So, I wanted to run the Visaton as low as possible, and just introduce the bass helper at the lowest octaves.
That's how I ended with the following setup:
1. Visaton high-passed (PLLXO), first order at 80 Hz
2. Eminence: 2nd order active at 60 Hz + a 3.3 mH inductor between a bass amp and the Eminence. (so that would be active/passive combination). This tamed some upper muddiness that was present when only 1st order low pass was running.
Actually it seems that inductor does not make a big difference, but somehow it sounds better when it's in the circuit (maybe it's just raising the Q of the Betas or introducing a phase shift)
Overall, it does not sound that bad. I like this setup more than when the Visatons and the Eminences are crossed higher (like 250 hz, what is mostly suggested) ...
Regards,
Vix
The Eminence's "natural" rising response combined with the response of an open baffle wouldn't make a first order lowpass actually act like a crossover. It would act more like an EQ network to make the response FLAT.
BUT it is a good starting point. If you get the response of the woofer reasonably flat with a first order lowpass you can start to design the "real" crossover.
Regards
Charles
Vix said:
One possible explanation is the huge cone breakup of the Betas not being sufficiently attenuated by a first order crossover. There should be also a dipole peak in the midbass that should be taken care of (a lowpass inductor should normally do the job in equalizing the dipole, though).
Vix said:
I also preferred crossing lower in a slightly different situation: Eminence Alpha15A in Y Baffles + miniminitors. I ended up crossing at 160 Hz.
phase_accurate said:
Right!
You have a big baffle there, so you can actually move the x-over point up a bit, because the 15 won't need as much EQ as on a smaller baffle.
Try bringing the Visaton x-over point way up, like to 900Hz or more. That way the 2 drivers won't be fighting each other so much in the lower mids. See how that sounds, then start rolling off the top end of the 15. You would do that with a small cap after the coil in a passive x-over. Don't be afraid of the midband gap. When you get some of the break-up nasties out, you may be able to bring the Visaton down to fill in the gap.
A couple of other things that may be bothering you are the reflective surfaces on the back of the baffle, the semetrical wings and the center placement of the Visaton. If you can do anything about those, it will help.
But moslty it's going to be in the crossover.
You seem to be on the right path. Once you find it, it will click and you'll love it.
Hey Vix-
It seems more crossover work is in order, but you might want to look at a different bass driver.
I'm going to build an OB with the B200 with a Dayton IB15, and the difference compared with the Eminence Beta15 is interesting.
They have similar Qts, but looking at the frequency response, they are a bit different, and I think the IB15 has some good advantages. Although its specs say its 8dB less efficient then the Eminence (88dB versus 96dB), compare some frequency SPLs: At 40Hz the Beta15 is down to 80dB, while the IB15 still holds at 88dB; at 20 Hz the Beta15 is down to about 67dB, while the IB15 is steady at 86dB. Using the IB15, there will be less EQing and less frequency dependent power demand. I'd guess that the bass would sound less 'flabby'.
Then, much higher up, the Beta15 has a broad 5 to 10dB peak from 600 to 3000Hz. It seems you might be hearing this (the plastic can sound). The IB15 drops like a brick after 1000Hz, so you won't get that upper midrange 'can' sound coming out of the bass driver (although it has a sharp drop between 700-800, I don't think this would be nearly as much of a problem).
Just food for thought. 😀
Good luck and keep on working, I'm sure it'll work out.
It seems more crossover work is in order, but you might want to look at a different bass driver.
I'm going to build an OB with the B200 with a Dayton IB15, and the difference compared with the Eminence Beta15 is interesting.They have similar Qts, but looking at the frequency response, they are a bit different, and I think the IB15 has some good advantages. Although its specs say its 8dB less efficient then the Eminence (88dB versus 96dB), compare some frequency SPLs: At 40Hz the Beta15 is down to 80dB, while the IB15 still holds at 88dB; at 20 Hz the Beta15 is down to about 67dB, while the IB15 is steady at 86dB. Using the IB15, there will be less EQing and less frequency dependent power demand. I'd guess that the bass would sound less 'flabby'.
Then, much higher up, the Beta15 has a broad 5 to 10dB peak from 600 to 3000Hz. It seems you might be hearing this (the plastic can sound). The IB15 drops like a brick after 1000Hz, so you won't get that upper midrange 'can' sound coming out of the bass driver (although it has a sharp drop between 700-800, I don't think this would be nearly as much of a problem).
Just food for thought. 😀
Good luck and keep on working, I'm sure it'll work out.
More food for thought:
According to the datasheet of the IB15, the driver is supposed to deliver 105dB SPL from 30 to 200Hz with a 35W input (simulated infinite baffle). That seems pretty do-able, and may well be a great match for the 96dB SPL B200...
Thats also 102db with a 17W input 😀 😀 😀 😀
According to the datasheet of the IB15, the driver is supposed to deliver 105dB SPL from 30 to 200Hz with a 35W input (simulated infinite baffle). That seems pretty do-able, and may well be a great match for the 96dB SPL B200...
Thats also 102db with a 17W input 😀 😀 😀 😀
If you can impliment a true infinite baffle with the IB15 and run the Visaton either with or without a tweeter, I think you'll be that much closer to your goal.
I have IB bass with the Daytons,(2 of them in parrallel), powered by a plate amp and a 2-way design with the b200's and Visaton G25FFL tweets on an open baffle with 3rd order x-over and am this close to "being there".
Main complaint is lack of punch in mid bass, but bottom end and mids and highs are quite pleasing. Punch increses with volume, but the xmax of the B200 only goes so far....
I have IB bass with the Daytons,(2 of them in parrallel), powered by a plate amp and a 2-way design with the b200's and Visaton G25FFL tweets on an open baffle with 3rd order x-over and am this close to "being there".
Main complaint is lack of punch in mid bass, but bottom end and mids and highs are quite pleasing. Punch increses with volume, but the xmax of the B200 only goes so far....
If you are looking at the Eminence data sheet and the plotted SPL for the Beta there may be some confusion. I believe that the plotted SPL on the data sheet is for the Beta in a test box not in a baffle. I remember reading that Eminence had done this for some reason. If you plot the T/S generated SPL response, which has to e accurate at low frequencies, it will not look anything like the data sheet SPL plot.
Hello VIX,
I still run OB & use a helper woofer also. I used B200 for over a year in differant configurations. I settled w/ bi-amping via BASH plates on a pair of Vifa M26wr-0908's & now PIM-8L's ran fullrange with no filters, then the Vifa brought at about 80 or less. You get into terrible territory when going above 80hz. I go for complete coherance & take the lighter non-impact bass of the Vifa's as it fills in nicely & has percieved speed that is unreal. integration is a non-issue as it also was with the B200. The peak of the B200 was allways my problem & finally gave into to letting them go. I would simplely bi-amp with with BASH plates & at least use 4th active on the bass unit & use no XO on the B200, maybe linelevel EQ for filling mid bass or active. digital etc for same duty as mid bass does suffer .. but most can live with that..All I can say is I have never had bass integration problems using the simple BASH plates in either 300 series or 500. I did not see if you have phase plugs, hopefilly you do. None of the line level filter ever made it for me in the long run as I still feel they are life suckers of Dynamics & such. My listen room is small hence getting away with the small but very good Vifa M26wr's. I have also tried all kinds of active XO & all have failed my personal tests. so filter free with tube gear on the fullrangers is al that makes myself happy. again my driver integration is allways seemless & never has been a problem in OB...now top end help was a whole diifarant story & have abondanded ST via ribbons or anything alltogether..hopefully never to return down that road. I have never measured anything speaker wise & do not think you need to do so eather to get seemless integration..If you have human voice cracking out of that bass unit all will be bad for you IMO...You might also be the true single driver type guy as I mostly am.
I still run OB & use a helper woofer also. I used B200 for over a year in differant configurations. I settled w/ bi-amping via BASH plates on a pair of Vifa M26wr-0908's & now PIM-8L's ran fullrange with no filters, then the Vifa brought at about 80 or less. You get into terrible territory when going above 80hz. I go for complete coherance & take the lighter non-impact bass of the Vifa's as it fills in nicely & has percieved speed that is unreal. integration is a non-issue as it also was with the B200. The peak of the B200 was allways my problem & finally gave into to letting them go. I would simplely bi-amp with with BASH plates & at least use 4th active on the bass unit & use no XO on the B200, maybe linelevel EQ for filling mid bass or active. digital etc for same duty as mid bass does suffer .. but most can live with that..All I can say is I have never had bass integration problems using the simple BASH plates in either 300 series or 500. I did not see if you have phase plugs, hopefilly you do. None of the line level filter ever made it for me in the long run as I still feel they are life suckers of Dynamics & such. My listen room is small hence getting away with the small but very good Vifa M26wr's. I have also tried all kinds of active XO & all have failed my personal tests. so filter free with tube gear on the fullrangers is al that makes myself happy. again my driver integration is allways seemless & never has been a problem in OB...now top end help was a whole diifarant story & have abondanded ST via ribbons or anything alltogether..hopefully never to return down that road. I have never measured anything speaker wise & do not think you need to do so eather to get seemless integration..If you have human voice cracking out of that bass unit all will be bad for you IMO...You might also be the true single driver type guy as I mostly am.
JandG said:
Thanks! I fully agree with everything that you said. I agree that the best crossover is no crossover and simply love that fullrange sound. There's a PLL filter that Geoff's designed to tame the Visaton's shout. Even though the sound may be a bit less detailed, I can't stand the shout and can't listen to B200 without a filter. I am not using phase plugs yet; planing to do so.The amp is Pass Zen V9 (without feedback) which is a great SS amp with almost "tube" sound.
As you noticed, only the lowest crossovers settings worked for me. I preferred Visaton run fullrange, but nevertheless I did a HP at 80 Hz because I wasn't comfortable with Visaton's excursion at high volumes ...
In the long run, I may end with replacing both Visatons and Eminence...
In the meantime, they serve as a good basis for a tutorial....
Best regards,
Vix
Hi Vix
What are the dimensions of your baffle? Just curious because I've been running some sims for my own project.
Though I doubt the computer sims are right on, they say that my Selenium 15" with a FR mid will need some radical values to sound right. I should be able to confirm that soon.
We're talking 15mH on the woofer and about 8uF on the fullrange = attenuation. Will be interesting to see how close real world is.
What are the dimensions of your baffle? Just curious because I've been running some sims for my own project.
Though I doubt the computer sims are right on, they say that my Selenium 15" with a FR mid will need some radical values to sound right. I should be able to confirm that soon.
We're talking 15mH on the woofer and about 8uF on the fullrange = attenuation. Will be interesting to see how close real world is.
Thanks for the dimensions, Vix.
About the same size as a pair of baffles I have at home.
I have been trying to simulate your baffle and drivers with MJK mathcad worksheets, but mathcad is soooooo slow on my computer. And the woofer results don't look right, anyway, spl much too low..
Maybe x-baffle will give a rough idea. Gonna check it out.
About the same size as a pair of baffles I have at home.
I have been trying to simulate your baffle and drivers with MJK mathcad worksheets, but mathcad is soooooo slow on my computer. And the woofer results don't look right, anyway, spl much too low..
Maybe x-baffle will give a rough idea. Gonna check it out.
It seems that Martin already simulated it, and it turned out that the discrepancy between Betas and Visatons is so huge that even when biamping, it will be way too hard to achieved a balanced response...
Hi,
Playing with Ob's again...
The crossover points have been slightly changed, and it sounds better this way:
Bass: 2nd order active low pass at 75 Hz + a 3 mH inductor in series with the Betas.
Visaton: High-pass at 125 Hz.
Now the transition is smoother, but I noticed that I have a problem elsewhere: A peak at 40 Hz? I've played some test tones:
http://homerecording.about.com/od/homestudiobasics/a/test_tones.htm
from 20-100 Hz. I got a solid 30 Hz, then there's a huge peak at 40 Hz. 50hz sounds much quieter than 40 Hz. 60 Hz and upwards it sounds more balanced. How is that possible? Do I need a notch at 40 Hz?I did not do any measurements, just listened.
Test tones that I found were not the best samples. It would be nice if somebody could tell me where to find a wider range of test tones (or maybe a program that does it).
Thanks ,
Vix
Playing with Ob's again...
The crossover points have been slightly changed, and it sounds better this way:
Bass: 2nd order active low pass at 75 Hz + a 3 mH inductor in series with the Betas.
Visaton: High-pass at 125 Hz.
Now the transition is smoother, but I noticed that I have a problem elsewhere: A peak at 40 Hz? I've played some test tones:
http://homerecording.about.com/od/homestudiobasics/a/test_tones.htm
from 20-100 Hz. I got a solid 30 Hz, then there's a huge peak at 40 Hz. 50hz sounds much quieter than 40 Hz. 60 Hz and upwards it sounds more balanced. How is that possible? Do I need a notch at 40 Hz?I did not do any measurements, just listened.
Test tones that I found were not the best samples. It would be nice if somebody could tell me where to find a wider range of test tones (or maybe a program that does it).
Thanks ,
Vix
Good to see that you're back at it! Don't give up.
Did you try swapping polarity of one of the drivers to hear if it changes?
For a nice, small tone generator, try this little fellow from down under:
NCH Tone Generator
Plenty of settings and adjustments, waveforms, etc. You can even save the tones as wav files.
Did you try swapping polarity of one of the drivers to hear if it changes?
For a nice, small tone generator, try this little fellow from down under:
NCH Tone Generator
Plenty of settings and adjustments, waveforms, etc. You can even save the tones as wav files.
Thanks!
I'll have a look. I need to try some more combinations, and see where's the problem coming from. It was quite surprising to hear that peak at 40 Hz. It was noticeable with music, some bass notes were overpowering, and some were very weak. Maybe part of the fault is the shape of my baffles, (more U than just a baffle).
I'll try to put some damping at the inner walls of the baffle. Or maybe it's the speaker resonance...(but at 40 Hz?)
Vix
I'll have a look. I need to try some more combinations, and see where's the problem coming from. It was quite surprising to hear that peak at 40 Hz. It was noticeable with music, some bass notes were overpowering, and some were very weak. Maybe part of the fault is the shape of my baffles, (more U than just a baffle).
I'll try to put some damping at the inner walls of the baffle. Or maybe it's the speaker resonance...(but at 40 Hz?)
Vix
Vix,
40 Hz is most likely excited by the room. Certainly it´s NOT the U-frame and damping the baffle will help nothing with a 40 Hz peak. Try toeing in the baffles 90° until they face one another. Is the peak much attenuated? Then I would bet its the room.
40 Hz is most likely excited by the room. Certainly it´s NOT the U-frame and damping the baffle will help nothing with a 40 Hz peak. Try toeing in the baffles 90° until they face one another. Is the peak much attenuated? Then I would bet its the room.
- Status
- Not open for further replies.