Good to know! I'll take this into consideration when I do further research. It looks like it will come down to reversing the cone cone pair in my current sub or building a cubo-something. Building a cubo will give me a fallback to my current sub. In my situation where I can't be caught without a working sub, this is a very important consideration.
Hi Zero D, it's good you pointed this out. It's high time I tested the drivers empirically with my DATS in parallel, series, and individually to shed some light on this question. Prior to building my isobaric sub, I read similar articles about isobaric and believed Fs did not change.
Perhaps it doesn't change, perhaps it does change a little but isn't halved. I should have confirmed with test equipment by now what my ears have observed-- parallel has the least LF extension, series has greater extension, and discretely driven seems to have the greatest extension.
I could be imagining things however, so I reserve the right to change my opinion.
So far no direct A/B tests have been performed on this. I will have the time to test the drivers next week. Until then!
Perhaps it doesn't change, perhaps it does change a little but isn't halved. I should have confirmed with test equipment by now what my ears have observed-- parallel has the least LF extension, series has greater extension, and discretely driven seems to have the greatest extension.
I could be imagining things however, so I reserve the right to change my opinion.
So far no direct A/B tests have been performed on this. I will have the time to test the drivers next week. Until then!
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@ Thetwinmeister
I agree that there could be a shift in fs. Variations in drivers T/S, & Volume of the shared enclosure, being just 2 possibilities that spring to mind !
@ Joseph Crowe
We've all done it from time to time I thought it best to point it out ASAP so others reading it too are clear on this.
Regards
I agree that there could be a shift in fs. Variations in drivers T/S, & Volume of the shared enclosure, being just 2 possibilities that spring to mind !
@ Joseph Crowe
We've all done it from time to time
I thought it best to point it out ASAP so others reading it too are clear on this.Regards
Driver testing is still in the future, in the meantime I have a couple of updates from my latest escapade.
Yesterday night I provided reinforcement for three college bands from two states in a praise and worship night, one of the groups being my regular guys. (None of these bands are professional if anyone had that idea, but this fact allows great liberty.) I was able to test the upper limits of my entire system from source to speaker. Even my soundboard was pushed heavily.
Sub: My dual pair isobaric sub performed fantastically on both 4-string bass guitar and kick drum mic'ed with a Sennheiser e902. Currently I have each of the 18" Dayton PA460-8 drivers discretely amplified utilizing two Behringer iNuke NU1000 amplifiers. I choose discrete amplification over something like wiring the pairs in parallel for two 4ohm loads and setting each amp in bridged mode because the former sounds so obviously superior to the latter I immediately wrote it off as even an option. At one point I pushed these amps so hard I said to myself "well, I did purchase the extended warranty..." but thankfully not only did they hold up but performed flawlessly even when I asked too much of them. I suppose I really need higher powered amps, my sealed isobaric is hungry.
Ah, you noticed those 18" drivers cost less than $100 each? Partly I wanted to prove (read: find out) that (if) two drivers half the cost of a single when coupled in a pair could outperform the single driver. Mostly it was due to budget considerations and an unwavering desire to go isobaric. I have lived to not regret my choice. Whether two of those are better than a given $200 driver (take your pick) is something I have yet to discover. Immediately, I take note the $200 driver has more xmax and is more sensitive.
Not a note from the bass guitar was missing or lacking, even at considerably high SPL. Another notable thing; I never passively noticed distortion at any level! Whether I would have picked up on it if I had purposefully listened for it is another thing however, I did not have time to do so. Even if I did, I'm not sure I would know how to evaluate with apparent distortion levels seemingly so low! My faith in this design concept has been fully reinvigorated. I may focus on perfecting it rather than attempting alternate designs from scratch.
The bass guitar required no EQ, however I had to EQ the kick drum substantially. I suspect this is due to two things: The kick drum my drummer uses is sealed. No traditional hole to mic. I might be doing it wrong. Secondly as I have mentioned before, the radio labs "stick on" sub crossover I am using doesn't have a very nice sounding rolloff. I believe it is due to these two reasons, and not a fault in the e902 microphone, that the kickdrum required heavy EQ to sound right. With EQ, the kick was powerful and sounded good, matching the rest of the kit well.
I am considering a balanced miniDSP to replace the radio labs until I can afford a driverack or equivalent Behringer. To those reading this in the future: The balanced miniDSP costs a dinner out more than the radio labs sub crossover. Consider your options wisely.
Mains: I don't think I have the crossover right. However, much better news is that somehow I am no longer hearing distortion from the Dayton D250P-8 compression drivers as I was before. In fact, even the tone is a little different. Where as before it was slightly warm, now it seems cold almost to be described as hollow. I do not have an immediate explanation for this other than pointing my finger at burn-in and shrugging my shoulder. Unfortunately I did not have my SPL meter with me, so all I can say it was loud, really loud, much louder than I've ever pushed the speakers before, and I never heard distortion. (From any driver at that!)
About the almost-hollowness; it's more welcome than distortion. I still would like to improve upon these drivers, however the necessity is less pronounced now. I may end up choosing to wait and purchase a driverack or similar before replacing something that already works. For information sake, the mains are run from an NU1000DSP amp with a HPF @ 80hz.
Mics: Unrelated to the thread, but I have to throw this in here. Subform appropriate! The venue allowed us access to two Sure Beta 58a microphones. Among other configurations, one of the bands had 4 vocalists simultaneously during a song. After my two Sennheiser e935 mics were utilized, I mic'ed the remaining vocalists with a Beta 58a throughout the performances. I have used the Beta 58a in the past, but never in direct comparison to an e935. Both are excellent microphones, both have great clarity, both stand up well in really loud environments, both cut through the mix, both have high gain-before-feedback, and both EQ well. However, putting aside as much prejudice as I can, I admit to find the e935 notably superior in all of these aspects. (With appropriate vocalist-related EQ applied to each, respectively.) I love the Sennheiser e900 series!
One of the musicians and lead singers came up to me afterwards and estimated I had $10,000 invested into this system. I don't know whether he knew a lot about PA system pricing, but his gesture made me smile. If you can't tell from my Dayton subs and Behringer amps, it's a lot less than $10,000. Although the mics are nice. Can't be awesome without those guys.
Yesterday night I provided reinforcement for three college bands from two states in a praise and worship night, one of the groups being my regular guys. (None of these bands are professional if anyone had that idea, but this fact allows great liberty.) I was able to test the upper limits of my entire system from source to speaker. Even my soundboard was pushed heavily.
Sub: My dual pair isobaric sub performed fantastically on both 4-string bass guitar and kick drum mic'ed with a Sennheiser e902. Currently I have each of the 18" Dayton PA460-8 drivers discretely amplified utilizing two Behringer iNuke NU1000 amplifiers. I choose discrete amplification over something like wiring the pairs in parallel for two 4ohm loads and setting each amp in bridged mode because the former sounds so obviously superior to the latter I immediately wrote it off as even an option. At one point I pushed these amps so hard I said to myself "well, I did purchase the extended warranty..." but thankfully not only did they hold up but performed flawlessly even when I asked too much of them. I suppose I really need higher powered amps, my sealed isobaric is hungry.
Ah, you noticed those 18" drivers cost less than $100 each? Partly I wanted to prove (read: find out) that (if) two drivers half the cost of a single when coupled in a pair could outperform the single driver. Mostly it was due to budget considerations and an unwavering desire to go isobaric. I have lived to not regret my choice. Whether two of those are better than a given $200 driver (take your pick) is something I have yet to discover. Immediately, I take note the $200 driver has more xmax and is more sensitive.
Not a note from the bass guitar was missing or lacking, even at considerably high SPL. Another notable thing; I never passively noticed distortion at any level! Whether I would have picked up on it if I had purposefully listened for it is another thing however, I did not have time to do so. Even if I did, I'm not sure I would know how to evaluate with apparent distortion levels seemingly so low! My faith in this design concept has been fully reinvigorated. I may focus on perfecting it rather than attempting alternate designs from scratch.
The bass guitar required no EQ, however I had to EQ the kick drum substantially. I suspect this is due to two things: The kick drum my drummer uses is sealed. No traditional hole to mic. I might be doing it wrong. Secondly as I have mentioned before, the radio labs "stick on" sub crossover I am using doesn't have a very nice sounding rolloff. I believe it is due to these two reasons, and not a fault in the e902 microphone, that the kickdrum required heavy EQ to sound right. With EQ, the kick was powerful and sounded good, matching the rest of the kit well.
I am considering a balanced miniDSP to replace the radio labs until I can afford a driverack or equivalent Behringer. To those reading this in the future: The balanced miniDSP costs a dinner out more than the radio labs sub crossover. Consider your options wisely.
Mains: I don't think I have the crossover right. However, much better news is that somehow I am no longer hearing distortion from the Dayton D250P-8 compression drivers as I was before. In fact, even the tone is a little different. Where as before it was slightly warm, now it seems cold almost to be described as hollow. I do not have an immediate explanation for this other than pointing my finger at burn-in and shrugging my shoulder. Unfortunately I did not have my SPL meter with me, so all I can say it was loud, really loud, much louder than I've ever pushed the speakers before, and I never heard distortion. (From any driver at that!)
About the almost-hollowness; it's more welcome than distortion. I still would like to improve upon these drivers, however the necessity is less pronounced now. I may end up choosing to wait and purchase a driverack or similar before replacing something that already works. For information sake, the mains are run from an NU1000DSP amp with a HPF @ 80hz.
Mics: Unrelated to the thread, but I have to throw this in here. Subform appropriate! The venue allowed us access to two Sure Beta 58a microphones. Among other configurations, one of the bands had 4 vocalists simultaneously during a song. After my two Sennheiser e935 mics were utilized, I mic'ed the remaining vocalists with a Beta 58a throughout the performances. I have used the Beta 58a in the past, but never in direct comparison to an e935. Both are excellent microphones, both have great clarity, both stand up well in really loud environments, both cut through the mix, both have high gain-before-feedback, and both EQ well. However, putting aside as much prejudice as I can, I admit to find the e935 notably superior in all of these aspects. (With appropriate vocalist-related EQ applied to each, respectively.) I love the Sennheiser e900 series!
One of the musicians and lead singers came up to me afterwards and estimated I had $10,000 invested into this system. I don't know whether he knew a lot about PA system pricing, but his gesture made me smile.
If you can't tell from my Dayton subs and Behringer amps, it's a lot less than $10,000. Although the mics are nice. Can't be awesome without those guys.
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500 watts seems to be the magic number for mains. It's terrifying at first using that much power into modest sized speakers but you quickly realize they handle it fine. (Crossed over) and if your continuously listening for any signs of clipping.
Good job on sound!
Did you ever get a chance to measure your mains using the Dayton reference mic? It will reveal a lot. +/-3 dB is my rule. I had 3 dB bumps in the midrange that once fixed sounded 10 times better.
Good job on sound!
Did you ever get a chance to measure your mains using the Dayton reference mic? It will reveal a lot. +/-3 dB is my rule. I had 3 dB bumps in the midrange that once fixed sounded 10 times better.
Thanks!
Where did you get 500 watts? Is that from empirical experience? I've used as little as 75 watts for live sound reinforcement (on a different pair of speakers) for a small audience with no real headroom issues, although mixing is honestly a little tighter. The NU1000DSP puts 150w into 8ohms. With the LTA's sensitivity of 97.7db, that works out to 123.2db at 3 feet. 500w increases that to 128.5db.
Mathematically, that's only 5.3db more. I have no experience mixing more than 150 watts, so I can only speak from mathematical terms to say 5.3db doesn't seem like much more for a 350 watt increase. 75w turns out to 120.2db.
Does 5.3db really make that much of a difference? Then again, going from 75w/120.2db to 150w/123.2db did afford noticeable breathing room. Only being a 3db increase.
I'm still looking forward to it! I haven't procured an adequate testing space. It's kind of silly though, I already have all the equipment I need to test and flatten the speaker's frequency response, (NU1000DSP) but I just haven't done it yet. I need to get my tail on that project!
Oh sorry, I looked up the spec on the Behringer and it said 500 watts, however that's at 2 ohm! I had to dig very deep to see what the rating was for 8 ohm, 160 watts. I was thinking this was similar to what I've been using (Crown XLS-2500) at 440 watts per channel at 8 ohm. It was just my experience that bumping up in power produced a system that could play shockingly loud and clean. Depends on many factors of course.
That does make sense, having higher headroom with ~500w would equate to lower THD vs squeezing every last watt out of a lower wattage amp. Amplifier upgrades are in my future, for sure! One day I would like to upgrade to Crown all around.
The wedding season is over. Successful season. I never got a chance to upgrade to the B&C compression driver, so I stuck it out with the Dayton. Until recently I almost took back any negative words I gave to it, but I think it became damaged two gigs ago.
During certain frequency reproduction, distinct distortion is present. At first, almost unnoticeable, but half way through dinner music at the last reception of the season for us, it became horrible. (Did I mention I picked up a balanced 2x4 miniDSP awhile back?) I was able to avoid disaster by switching the Eminence to full range again, lowering the level of the Dayton compression driver, and increasing the xo frequency on it. I think I'll be upgrading to the B&C before the next season. But now I'm more conserned than ever with power handling.
I had a thought though, what if it wasn't over power-ing that killed my Daytons? Has anyone ever attributed CD failure to subwoofers? My sub literally resonates my pants, couldn't it's SPLs also effect sensitive diaphragms adversely?
During certain frequency reproduction, distinct distortion is present. At first, almost unnoticeable, but half way through dinner music at the last reception of the season for us, it became horrible. (Did I mention I picked up a balanced 2x4 miniDSP awhile back?) I was able to avoid disaster by switching the Eminence to full range again, lowering the level of the Dayton compression driver, and increasing the xo frequency on it. I think I'll be upgrading to the B&C before the next season. But now I'm more conserned than ever with power handling.
I had a thought though, what if it wasn't over power-ing that killed my Daytons? Has anyone ever attributed CD failure to subwoofers? My sub literally resonates my pants, couldn't it's SPLs also effect sensitive diaphragms adversely?
No. Are both drivers making the same noises? Have you checked to see if they have worked lose from the horns? This is common with thread on drivers. Also what crossover are you using with them.. freq and slope? The good news is if the diaphrams are damaged they're easily replaced and not that expensive.
Good point. Not sure how to tell, though. If the sub would be loud enough to resonate the diaphragm of the CD, how am I supposed to tell whether the CD is resonating with my ears alone?
Also, even if it resonated once and never did such again, just one time should be enough to physically damage them from "over excursion," no?
I have not, but I will. It's 2/3 bolt. Don't remember which. Those should have less chance of detachment, right?
Admittedly, my crossover is weird. At first I went with first order 4khz passive, then I became aware I may run into power handling issues. So I purchased a DSP and crossed it below the passive at 2k 48db/octave, never removing the passive. When it went to distortion city, I increased the xo to 3khz.
The comfort of having a passive in case of the unknown was nice, and I can't really imagine why it would hurt anything. Maybe introduce some unnecessary phase shifting, but surely not damage.
The only way this could possibly happen is if the compression drivers were completely unpowered and disconnected from everyhting, and positioned right in front of the subs at point blank range when the they were being powered at full warp. Otherwise this will not happen because a speaker works both ways..
a) you apply a voltage to the coil and it produce cone movement.
b) you move the cone and it produce a voltage in the coil.
And when a speaker is connected to a live amplifier any cone movement generates a back EMF that the amp resists so it's like the driver has a brake on it. You also get the same result if the driver is shorted, you can try that yourself with a woofer, push in on the cone when it's not connected to anything and it will move, but when connected to an amp or when shorted you won't be able to move the cone.. at least not easily and not very far or fast.
less likely but not impossible unless the bolts have loktite on them.
These things should be plenty safe at 2khz 24db/oct so something strange happened and I'm sure you'll find it when you dig into the speakers and check out all the possibilities.
Yes that is right and many designs include a cap just below where the active crossover operates as protection just in case.
I see! It seems plain as day when you word it like that. I knew about back EMF, just didn't think it completely through.
I can't think of a time when the sub was at full power when these mains were disconnected from their amplifier, so that must not be the problem. Good.
Sounds good, I'll give these guys a comprehensive checkout.
I was debating whether to keep the cap should I upgrade the CD.
I say hold off any talk of upgrading the CD until you find out what went wrong, because it sounds like you were quite happy with the sound and performance. As for the cap definitely keep it but substitute a larger value so it's not affecting the response in pass band like the current one.
Can't find anything wrong. Set the system up, troubleshooted (nothing), unmounted the horns, inspected the bolts (It's 2-bolt) which were still secure, took out the caps, and played with the DSP crossovers the rest of the time. I settled at a nice rounded-number @ 3Khz 24db BW slope.* This was the first time with my nice miniDSP playing without a capacitor. The Dayton CDs like being cap-free. They're noticeably clearer without one. For the record, it was a Jantzen z-silver capacitor. It was of a relatively low capacitance for a high xo, so the z-silver series became affordable. That was my justification-- in case high-dollar-capacitor-scoffers are around.
With the miniDSP and no caps, I no longer have a reason to replace this Dayton CD. There's nothing wrong with it and the performance is satisfying.
I attribute the crazy distortion last gig to dirty AC line power. I'm going to buy a Furman PL-8 C and never again gig without a power conditioner. Not sure if saving for a voltage regulator conditioner is a worth-while endeavor.
*I'm going to keep playing with the crossovers. Once winter brings outdoor silence, I plan to fine-tune everything with calibrated measurement microphone.
With the miniDSP and no caps, I no longer have a reason to replace this Dayton CD. There's nothing wrong with it and the performance is satisfying.
I attribute the crazy distortion last gig to dirty AC line power. I'm going to buy a Furman PL-8 C and never again gig without a power conditioner. Not sure if saving for a voltage regulator conditioner is a worth-while endeavor.
*I'm going to keep playing with the crossovers. Once winter brings outdoor silence, I plan to fine-tune everything with calibrated measurement microphone.
I have seen(heard) passive crossover components cause distortion but it was a low voltage/low quality part being powered beyond what it was designed for, that should not be the case here. I wouldn't be surprised if the distortion was being generated somewhere upstream of the speakers, I once had a bass guitar rig with an excessively hot line out that was injecting a low level fuzz distortion over the whole mix, I should have put it on a DI or mic'd the cab but by the time I figured out where the noise was coming from the band was nearly done their set.
A small UPS with AVR is not a bad idea to put in place to protect the small signal components and especially anything digital, but it's a waste on amplifiers.
It does help to take a break from tuning and come back to it with fresh ears.
Nice--I've done enough live sound reinforcement to appreciate that situation. Nothing quite that bad, though. haha. Not yet.
So AVR (meaning nothing more than voltage regulation, I assume) is a waste on amps you say?
I've read the inverter on a UPS is all too frequently cheap, producing half sine waves.
Yes it does
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