David Gatti said:
Thanks David,
I've tried a lot of XO combinations and the 1st order stuff didn't sound as clean as what I have now.
2nd order I felt that there was perhaps more ambience or presence but slightly less detailing, I'm not sure.
When all is said and done I've spent the most time in the XO and measuring to perfect the cross points. What I have now is the best I can get them to sound, I can get them to measure better but they don't sound as right to me.
Many manufacturers make technically perfects speakers yet they all
sound different and gather different crowds that enjoy them. You
are basically saying you have a technically good design but it fails
to deliver the SQ you need. Why not de-tune the system and adjust
the setting by ear to see what you come up with.
sound different and gather different crowds that enjoy them. You
are basically saying you have a technically good design but it fails
to deliver the SQ you need. Why not de-tune the system and adjust
the setting by ear to see what you come up with.
thylantyr said:
Thanks for the suggestion Thy.
I don't want to sound like I'm throwing peoples advice away because I'm not. I value the input very much.
But...
I've done a lot of measuring and setting up then I've listened and gone back in tweaked by ear then measured again etc.
I think where I am is close to the maximum that I can get out of the drivers, actually I rephrase that, its very close to what I am able to extract from the drivers.
I've come to this with fresh ears after almost 2 months of building the new cabinets but I'm still not feeling what I was hoping for. I can't help but think I'm either not good enough to get these drivers working or they just don't work together full stop.
I'm going to do some measurements on the port output to see if I have any odd harmonics that could be messing the sound up. I made a point of stuffing the port though to make the cabinet act like a sealed one just for curiosities sake without any improvement - it sounded worse if anything.
What to do?
Do I change the driver yet again? I think its likely since I know I won't be happy in the long run.
I really don't want to scrap the project because I can see massive potential if I can nail this bass-mid compatiblity issue.
Not at all. We're just throwing suggestions at you for your consideration.ShinOBIWAN said:
It's starting to look like going from a rigid aluminium woofer to a lossy ATC dome is just not synergetic. Maybe a paper or poly woofer is the answer. Check these out :
http://www.audiotechnology.dk/iz.asp?id=4|a|127|||
Hi Shin,
Don't despair! You will resolve these technical dificulties. Because that's all they are, technical difficulties. Philosophically your project is beyond question. The subtle problems that you are facing here are the most difficult to identify and fix. But fix them you will. In a years time you will look back and wonder why the solution wasn't obvoius at the time.
If I may offer yet another view.
Pro monitors that I know use the ATC mid are Quested, PMC and ATC. Quested and PMC both use Volt drivers, ATC use their own drivers. I've only heard ATC monitors, but the others, particularly the PMC are also rated very highly.
Perhaps following the crowd on this one may be the way forward. Volts seem relatively inexpensive and readily available so they would be my first suggestion. In fact I have ATC mids and B250's on order at the moment so I'm probably biased towards this combination. Unfortunately I am at least 6 months behind you with construction, so I can't offer you any first hand advice at the moment.
Never give up!
Cheers,
Ralph.
Don't despair! You will resolve these technical dificulties. Because that's all they are, technical difficulties. Philosophically your project is beyond question. The subtle problems that you are facing here are the most difficult to identify and fix. But fix them you will. In a years time you will look back and wonder why the solution wasn't obvoius at the time.
If I may offer yet another view.
Pro monitors that I know use the ATC mid are Quested, PMC and ATC. Quested and PMC both use Volt drivers, ATC use their own drivers. I've only heard ATC monitors, but the others, particularly the PMC are also rated very highly.
Perhaps following the crowd on this one may be the way forward. Volts seem relatively inexpensive and readily available so they would be my first suggestion. In fact I have ATC mids and B250's on order at the moment so I'm probably biased towards this combination. Unfortunately I am at least 6 months behind you with construction, so I can't offer you any first hand advice at the moment.
Never give up!
Cheers,
Ralph.
I usually recommend building a prototype to test synergy so
is this your prototype now? /hehe
There is nothing wrong by re-examining the design, I know I've
changed my mind alot for my project but I need to do more tests boxes to verfiy. If it takes a few more attempts so be it, the goal is to have
'the one' system you like and ideally the one to keep for a long time.
re: Seas
Is that woofer generating enough bass and midbass that you desire?
Do you like the lower midrange sound?
is this your prototype now? /hehe
There is nothing wrong by re-examining the design, I know I've
changed my mind alot for my project but I need to do more tests boxes to verfiy. If it takes a few more attempts so be it, the goal is to have
'the one' system you like and ideally the one to keep for a long time.
re: Seas
Is that woofer generating enough bass and midbass that you desire?
Do you like the lower midrange sound?
Cheers Thy.
It looks that way now. If I swap the bass yet again I'll almost certainly want to rebuild at least the bass section.
I'll have to see how my next bass driver choice fits into the existing cabinet. It may just need a port re-tune or may need to increase or decrease the volume.
I may get lucky but in audio I don't think there's such a things as luck just hard work 🙂
It just feels a little like wading through treacle at the minute. All the tests and measurements I have done suggest a sorted design yet the sound suggests otherwise. I've relied on my ears and that hasn't brought about any drastic changes.
Again both the ATC and Excel have SQ I like but when used in tandem don't work well. So I do like the Excel sound in the range I have it covering but not in context of the ATC.
The Sea's don't have any sort of serious extension and nor are they upto the task of doing decent SPL's down to their low limits in the cabinet I have. So a sub is still definitely on the cards.
thylantyr said:
It looks that way now. If I swap the bass yet again I'll almost certainly want to rebuild at least the bass section.
I'll have to see how my next bass driver choice fits into the existing cabinet. It may just need a port re-tune or may need to increase or decrease the volume.
I may get lucky but in audio I don't think there's such a things as luck just hard work 🙂
It just feels a little like wading through treacle at the minute. All the tests and measurements I have done suggest a sorted design yet the sound suggests otherwise. I've relied on my ears and that hasn't brought about any drastic changes.
Again both the ATC and Excel have SQ I like but when used in tandem don't work well. So I do like the Excel sound in the range I have it covering but not in context of the ATC.
The Sea's don't have any sort of serious extension and nor are they upto the task of doing decent SPL's down to their low limits in the cabinet I have. So a sub is still definitely on the cards.
David Gatti said:
Cheers David.
I think your right about the synergy between the Seas and the ATC.
I've never heard an audiotech driver but I've heard the bass drivers are quite dark. I'm not sure if this means overblown, heavy or slow but its a world that I don't like when I consider my own preferences.
I like the Sea's sound because its light and nimble and this is generally how I like my bass for music. HT is another matter!
ralphs99 said:
Thanks for the suggestions Ralph.
For what its worth I'm looking at ATC and Volt right now.
Hi Shin,
you've gone through a lot and with much dedication and effort. Like a PhD on speaker building.
A couple of things though are curiously absent, or maybe I missed them in these long threads in which case I ask for forgiveness for mentioning them.
- While you swapped drivers, you stuck with the boxed approach - ever considered dipole?
- while you did room response and room EQ as well as FR, you don't seem to consider off axis response and power response much
- talking of synergy, and of radiation patterns, how about possible ifluence of tweeter/mid integration on the perceived bass/mid integration? Influence of this sort are not as far fetched as they sound.
- stored energy can be an issue as mentioned in some above post - transparent metal cone meets well damped mid...
- metal drivers have these notorious break ups. You may not see an obvious effect in the overall FR , yet an undamped resonance could be audible even a couple dozen dB down.
I'd suggest to try and by all means finding out *what* didn't work out and *why* before swapping drivers again, or else it will just be dirver roulette...
you've gone through a lot and with much dedication and effort. Like a PhD on speaker building.
A couple of things though are curiously absent, or maybe I missed them in these long threads in which case I ask for forgiveness for mentioning them.
- While you swapped drivers, you stuck with the boxed approach - ever considered dipole?
- while you did room response and room EQ as well as FR, you don't seem to consider off axis response and power response much
- talking of synergy, and of radiation patterns, how about possible ifluence of tweeter/mid integration on the perceived bass/mid integration? Influence of this sort are not as far fetched as they sound.
- stored energy can be an issue as mentioned in some above post - transparent metal cone meets well damped mid...
- metal drivers have these notorious break ups. You may not see an obvious effect in the overall FR , yet an undamped resonance could be audible even a couple dozen dB down.
I'd suggest to try and by all means finding out *what* didn't work out and *why* before swapping drivers again, or else it will just be dirver roulette...
MBK said:
Hi MBK and thanks for the kind words.
No problem I know its sometimes a chore to read long thread, look at the 'Krell KSA50 PCB' thread in Solid State and you'll know what I mean! Most of what you've highlighted has already been measured and the outcomes look not far off ideal within the boundaries I have.
Here's a quick run through of what I've observed from measurements:
I've isolated both the ATC and Seas and run individual frequency and impedance/phase measurements both with and without the XO in place. The only one I haven't done this with, and its because I don't fancy piping a fullrange signal through it, is the Scan ring but that driver isn't the problem.
All the plots look fine no peaks no dips aside from cone breakup on the Seas around 2.5Khz. These are two very well behaved drivers as far as measurements go.
Impedance matching has nothing to do with this since its active buy I'll mention it anyway.
I've also tested the drivers mounted and free air. I'm showing the classic double impedance spike for the Seas mounted in a ported cabinet and they correlate well with the port tuning and driver Fs. The rest of the curve is well behaved aside from cone breakup. The ATC is remarkably flat in amplitude when mounted on the baffle with a minor ripple of around 2dB at 1.2kHz which relates to the baffle since it wasn't shown in free air measurments. I also think I've got a good baffle design because the free air vs. mounted on baffle responses look very similar.
I've checked to see if the cone breakup of the Excel is causing any unwanted sound output and with the high Q notch filters in place they are completely inaudable when testing using a high SPL frequency sweep with the XO in place and just the Excel playing in isolation.
Summation around the 380hz XO point is flat, no dips, no peaks which suggested good phase matching and indeed running a gated far field acoustic center response measurement with the mic 1.5m from the tweeter axis. It shows very good phase variance to within +50/-30 degrees from 130hz upto 18khz.
I've also run gated far field response on axis for each driver to check dispertion and off axis response. The ATC was quite exeptional here and the scan working well within this 'cone' of sound with a similar radiation pattern but more focused and limited in dispertion. Since the Excel is only used upto 400hz its actual dispertion pattern is naturally large low down and doesn't roll off until you start to get to around 50degrees and even then its only at around 300hz. All in all the dispertion of the ATC and Seas mate very well at 380hz suggesting a good candidate for a crossover point.
I did note some lobbing between the ATC and Scan at around 30 degree's off the horizontal axis. This seems to steady out though and the mid range becomes slighty more prounounced at 30+ degrees as the Scan starts to roll off rapidly above around 6Khz.
Because of my room I doubt dipoles would work well since they need room to breath.
Admittedly I haven't tested this assumption at all though.
This is where my thoughts currently lie.
That's what I'm worried of. I could swap drivers and things could be worse and that's yet more money down the pan. On the plus side, I'm building up a nice collections bass drivers for future testing and projects. 😀
Unfortunately in the DIY speaker quest there's just no substitute for trying out different drivers. There's only so much you can learn from the specs. That's the way the pros do it. And you can always Ebay the ones you reject later on.
Secondly I would be careful of your assumption that the high end is all good without having measured it. I have been in similar situations where I believed I had an LF or HF problem, where in reality it was problem at the other end of the spectrum. A perception of mid-bass shyness in one case was really a broad, upper midrange peak. Your hearing can sometimes play strange tricks on you!
Cheers,
Ralph.
Secondly I would be careful of your assumption that the high end is all good without having measured it. I have been in similar situations where I believed I had an LF or HF problem, where in reality it was problem at the other end of the spectrum. A perception of mid-bass shyness in one case was really a broad, upper midrange peak. Your hearing can sometimes play strange tricks on you!
Cheers,
Ralph.
ralphs99 said:
Thanks for the heads up Ralph but I guess you missed my previous posts.
If you read the post above yours you'll see that I've been into detail on the testing and measurements of all the range.
I've done extensive measuring/testing and nothing whatsoever is wrong with the the stuff the Seas, ATC and Scan are covering its only when listening that I don't feel its right. I've tweaked by ear extensively also, no result.
If there's a problem with the upper range thats influencing the Seas then I can't hear or measure it 😉
The response is as flat as a pancake as well.
Member
Joined 2003
The Seas plots show breakup peaking between 4-5Khz (same as the ones I have) 2.5k breakup could point to a defective driver??
Hi Shin,
the situation is really quite complicated because you have such a complex setup (which most ppl here including myself don't completely understand, nevermind have heard). So there are many subtle possible issues that could fall under the table. And in the end it might turn out to be that factor that seemed negligible at first 😉
Dipole works for me - but I don't think this is your issue here. And the driver material - well it's an easy hypothesis, but shouldn't good drivers with well corrected anomalies and otherwise good specs at least be reasonably close? I feel a bit uneasy thinking it's just the drivers.
If it IS the drivers, most likely it's a difference in the *type* of distortion, not the *level*, that shows up as an audible mismatch.
Anyway, if off axis response is well matched, cone breakups far away etc, here some more theories:
Group delay or the absence thereof, with consequences.
I don't know about the intricacies of your digital X-O. AFAIK however, there is a way of building digital X-O's similar to regular ones (i.e. with group delay), and a way that works w/o group delay.
A) if you do have group delay in your X-O's, you might end up with correct phase between drivers, but with the timing being off. Quite possible when using conventional LR4's and running the woofer LP straight from the input. Solution is to run the woofer LP through the mid LP first, to add the group delay that the mid sees, to the one that the woofer will get.
B) even if this is not an issue, drivers themselves will have different group delay, mostly accumulating in the bass. So your X-O and FR looks perfect, but timing is off at the mid-woofer X-O
C) if you use a digital X-O that does eliminate phase distortion, apparently this is done by introducing a pre-ringing in the crossover region. This pre-ringing cancels out perfectly - in theory, and only on axis! Linkwitz has a nice discussion of this on his website. No idea how your FIR filters wok, but that's a possibility. And DRC might make it worse, in that it throws a "correction" of the off axis ringing right back at you.
D) DRC itself. Besides the C) issue, you might simply overdo on the DRC. The room is in some respect necessary for a real-sounding system.
Possible experiments to address the above:
- listen outdoors and w/o DRC of course to eliminate off axis effects. Listen to both speakers exactly on axis in stereo for what elements change / improve - I assume you usually just pull a single one outdoors, and only to measure it.
- listen indoors, using a conventional (active) x-o built to match your digital x-o . Listen with and w/o DRC in and outdoors.
- generally speaking, try out radically different x-o points just to see what type of effect changes. Maybe an ultra low x-o like 200 Hz, which would not be sustainable at higher SPL's for the ATC , just to see how that would sound (sic). Or push the woofers to 500, 600 Hz.
- again, generally, just play with *level*, not with *curves*. I noticed that level changes of as little as 0.5 - 1 dB in tweeter level can make the difference between "dull" and "bright", not to mention perceived "wrongness" in integration. These differences would still look "ruler flat" on a typical averaged FFT. And, as pointed out by ralphs99, increased HF is equivalent to missing bass.
- especially pernicious: raised plateaus or otherwise unremarkable broadband mini peaks (+1 dB say) in the 3k-6k range can throw a lot of things off, subjectively.
All this is just guesswork though because the more complicated the system, the exponentially more potential problems. That's why some people stick with single drivers ;-)
Anyway should you change your woofers you might try polypropylene ones. I just ordered some SS8543, supposedly superbly clean midrange, to replace some paper full ranges that I use as mids in my dipole setup. I'll see if it sends me to heaven or screaming 😉 - hey maybe I'll consider a donation of your ATC's should you get tired of them, should be a great match 😉))
the situation is really quite complicated because you have such a complex setup (which most ppl here including myself don't completely understand, nevermind have heard). So there are many subtle possible issues that could fall under the table. And in the end it might turn out to be that factor that seemed negligible at first 😉
Dipole works for me - but I don't think this is your issue here. And the driver material - well it's an easy hypothesis, but shouldn't good drivers with well corrected anomalies and otherwise good specs at least be reasonably close? I feel a bit uneasy thinking it's just the drivers.
If it IS the drivers, most likely it's a difference in the *type* of distortion, not the *level*, that shows up as an audible mismatch.
Anyway, if off axis response is well matched, cone breakups far away etc, here some more theories:
Group delay or the absence thereof, with consequences.
I don't know about the intricacies of your digital X-O. AFAIK however, there is a way of building digital X-O's similar to regular ones (i.e. with group delay), and a way that works w/o group delay.
A) if you do have group delay in your X-O's, you might end up with correct phase between drivers, but with the timing being off. Quite possible when using conventional LR4's and running the woofer LP straight from the input. Solution is to run the woofer LP through the mid LP first, to add the group delay that the mid sees, to the one that the woofer will get.
B) even if this is not an issue, drivers themselves will have different group delay, mostly accumulating in the bass. So your X-O and FR looks perfect, but timing is off at the mid-woofer X-O
C) if you use a digital X-O that does eliminate phase distortion, apparently this is done by introducing a pre-ringing in the crossover region. This pre-ringing cancels out perfectly - in theory, and only on axis! Linkwitz has a nice discussion of this on his website. No idea how your FIR filters wok, but that's a possibility. And DRC might make it worse, in that it throws a "correction" of the off axis ringing right back at you.
D) DRC itself. Besides the C) issue, you might simply overdo on the DRC. The room is in some respect necessary for a real-sounding system.
Possible experiments to address the above:
- listen outdoors and w/o DRC of course to eliminate off axis effects. Listen to both speakers exactly on axis in stereo for what elements change / improve - I assume you usually just pull a single one outdoors, and only to measure it.
- listen indoors, using a conventional (active) x-o built to match your digital x-o . Listen with and w/o DRC in and outdoors.
- generally speaking, try out radically different x-o points just to see what type of effect changes. Maybe an ultra low x-o like 200 Hz, which would not be sustainable at higher SPL's for the ATC , just to see how that would sound (sic). Or push the woofers to 500, 600 Hz.
- again, generally, just play with *level*, not with *curves*. I noticed that level changes of as little as 0.5 - 1 dB in tweeter level can make the difference between "dull" and "bright", not to mention perceived "wrongness" in integration. These differences would still look "ruler flat" on a typical averaged FFT. And, as pointed out by ralphs99, increased HF is equivalent to missing bass.
- especially pernicious: raised plateaus or otherwise unremarkable broadband mini peaks (+1 dB say) in the 3k-6k range can throw a lot of things off, subjectively.
All this is just guesswork though because the more complicated the system, the exponentially more potential problems. That's why some people stick with single drivers ;-)
Anyway should you change your woofers you might try polypropylene ones. I just ordered some SS8543, supposedly superbly clean midrange, to replace some paper full ranges that I use as mids in my dipole setup. I'll see if it sends me to heaven or screaming 😉 - hey maybe I'll consider a donation of your ATC's should you get tired of them, should be a great match 😉))
Thanks MBK,
A lot of what you've suggested has been measured, verified and then tested by ear. Afterwards more tweaking by ear then measuring again to see the results. The great thing about the digital XO is can AB my changes to see if I'm actually heading in the right direction. Along the way I create checkpoints of a sort to keep going back to for reference.
Wouldn't group delay problems also show up in my phase measurements? Those were decent and I didn't need much correction at all in the XO. Good drivers make for a simplier if not neccessarily easier XO.
I test the speakers outside when the weather is decent. Once I get something I like the second speaker is setup with reference to the first rather than just use the same settings for both and not compensate for driver discrepancies.
I've had the system with DRC off and I've messed around with levels of each driver as well as XO points and not just the slopes. The PC XO allows you to hear changes you make on the fly so its very quick stuff allowing you to try all sorts of things in an hour that would take days with passive or analogue active.
I've got a busy weekend comming up but I'm going back to a passive setup just to finally eliminate and chance that the PC XO is causing me trouble.
A lot of what you've suggested has been measured, verified and then tested by ear. Afterwards more tweaking by ear then measuring again to see the results. The great thing about the digital XO is can AB my changes to see if I'm actually heading in the right direction. Along the way I create checkpoints of a sort to keep going back to for reference.
Wouldn't group delay problems also show up in my phase measurements? Those were decent and I didn't need much correction at all in the XO. Good drivers make for a simplier if not neccessarily easier XO.
I test the speakers outside when the weather is decent. Once I get something I like the second speaker is setup with reference to the first rather than just use the same settings for both and not compensate for driver discrepancies.
I've had the system with DRC off and I've messed around with levels of each driver as well as XO points and not just the slopes. The PC XO allows you to hear changes you make on the fly so its very quick stuff allowing you to try all sorts of things in an hour that would take days with passive or analogue active.
I've got a busy weekend comming up but I'm going back to a passive setup just to finally eliminate and chance that the PC XO is causing me trouble.
Paul W said:
On both of mine breakup starts at just above 2.5Khz.
I've just checked the Seas plots from their website and its close to what I have.
Thanks anyway though.
David Gatti said:
Overall, I agree with this conclusion as well, All the solutions here are really a band aid approach.
As far as my earlier suggestion are concerned.
Stuffing: overstuffing is bad, understuffing is worse. even with BR I would probably add 50% poly away from the woofer but still keep an open path to the port, I would also line the walls with felt/carpet pad/false wall etc. You really have to determine experimentally what works for you.
Speaker damage: there are a lot of people promoting exotic woofers etc, in this forum as in others, and I just want to point out there is a million ways to blow up speakers, especially when you are full active.
This is just a caution on exotic drivers, not specifically to anything you are doing.
Room effects: MBK and I already labored on room effects, but from your posts it seems you only did an FR graph, you should get RT60 values or a CSD from 20-1000 hz far field with long windowing/gating to really see what your room is doing. The room can completely change your sound.
Reverb: reverb is most definitely a hack, applied in small doses to your woofer you might actually like it. Definitely not for the purists.
Reverb is the mixing engineer's best friend.
As an additional note: You mentioned you like the Seas sound, but you preferred BR to closed and you liked the Mackie 626, a passive radiator design. I am sorta confused to what your as to your overall Low-mid frequency goals are.
I would not worry about 23cm spacing with a 400hz steep crossover.
If you finally do make the decision to scrap the bass unit:
You mentioned you heard and liked volt speakers and they are used in commercial speakers with atc mids, so that probably is a good place to start. I have no experience with Volt or ATC drivers so I cannot help you there.
Make simple test boxes/baffles first. It will not be perfect but will save your sanity.
if you were to look at other bass drivers to mate with the atc, may I suggest picking a driver with a low Le/Re ratio. You will have easier phase matching.
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