Hello Zaph,
I like your professional website, I guess it's the only place where I can have a look at professional measurements at all.
I am very interested in the new 7" Peerless speakers since they are cheaper than Seas' (especially my favourite CA18RNX) and as good as the Seas in the bass region.
If I ask politely, will you tell me when there is a chance that you measure some of these?
Greetings from Austria,
Loiti
I like your professional website, I guess it's the only place where I can have a look at professional measurements at all.
I am very interested in the new 7" Peerless speakers since they are cheaper than Seas' (especially my favourite CA18RNX) and as good as the Seas in the bass region.
If I ask politely, will you tell me when there is a chance that you measure some of these?
Greetings from Austria,
Loiti
John K. - Dayton DA/RS Question
"Well, I wouldn't call it problems with the DA175, just limitations of a lower tech motor design. The two types of distortion we're talking about here are thermal and BL. At lower levels, the DA175 performs on par with the Seas L18. As millimeters of Xmax get used up, the DA175's generic flat and straight pole piece causes BL distortion to accumulate faster than some better motor designs that have better BL curves.
Thermal is simply the driver's ability to maintain it's measurements at higher levels as the voice coil and suspension heat up. This can be easily seen in response and impedance curves that are increased in incremental levels. For example, starting at 90 dB/1m, then running response and impedance plots in increments at levels 5 or 10 dB higher to observe the changes.
This kind of testing is still somewhat important, but I usually don't do it due to time constraints. Soundeasy can do Volterra Series Expansion, which is more of an estimate of a BL curve rather than an actual Klippel-style measurement, but still useful. Some day I'll post a set of measurements so you guys can see what this looks like. I'll use the L18 and DA175 too, as these drivers really point out the difference that motor design can make. People want to just add up the Xmax, calculate out the volume displacement and use that to determine how loud a speaker will get, but it's not that simple. A single L18, through most of it's bandwidth, will play louder with lower distortion than two DA175's. Make no mistake that the DA175 is a great woofer, but the higher price of the L18 does get some performance improvements in this case...."
John - do the Dayton RS series woofers have the same limitations as the DAs, or is their motor design more sophisticated, allowing higher SPLs without as much power compression?
"Well, I wouldn't call it problems with the DA175, just limitations of a lower tech motor design. The two types of distortion we're talking about here are thermal and BL. At lower levels, the DA175 performs on par with the Seas L18. As millimeters of Xmax get used up, the DA175's generic flat and straight pole piece causes BL distortion to accumulate faster than some better motor designs that have better BL curves.
Thermal is simply the driver's ability to maintain it's measurements at higher levels as the voice coil and suspension heat up. This can be easily seen in response and impedance curves that are increased in incremental levels. For example, starting at 90 dB/1m, then running response and impedance plots in increments at levels 5 or 10 dB higher to observe the changes.
This kind of testing is still somewhat important, but I usually don't do it due to time constraints. Soundeasy can do Volterra Series Expansion, which is more of an estimate of a BL curve rather than an actual Klippel-style measurement, but still useful. Some day I'll post a set of measurements so you guys can see what this looks like. I'll use the L18 and DA175 too, as these drivers really point out the difference that motor design can make. People want to just add up the Xmax, calculate out the volume displacement and use that to determine how loud a speaker will get, but it's not that simple. A single L18, through most of it's bandwidth, will play louder with lower distortion than two DA175's. Make no mistake that the DA175 is a great woofer, but the higher price of the L18 does get some performance improvements in this case...."
John - do the Dayton RS series woofers have the same limitations as the DAs, or is their motor design more sophisticated, allowing higher SPLs without as much power compression?
Re: John K. - Dayton DA/RS Question
The RS woofers have a more advanced motor. The pole piece is undercut which always makes for a better BL curve. There's a single faraday ring mounted outside the voice coil on the inside of the magnet.
The DA woofers just have a generic plain straight and flat pole piece. Still, the performance is good for $18 each.
Honestly, I like the DA175 cone better than the RS180 cone. Much more controlled in the upper midrange, and a less harsh breakup without the twin peaks.
sdclc126 said:
The RS woofers have a more advanced motor. The pole piece is undercut which always makes for a better BL curve. There's a single faraday ring mounted outside the voice coil on the inside of the magnet.
The DA woofers just have a generic plain straight and flat pole piece. Still, the performance is good for $18 each.
Honestly, I like the DA175 cone better than the RS180 cone. Much more controlled in the upper midrange, and a less harsh breakup without the twin peaks.
Re: Re: John K. - Dayton DA/RS Question
Interesting! More advanced motor, more expensive, yet somewhat inferior performance. Well, that convinces me - I'm gonna abandon the RS idea. Back to the BAMTM. Since they'll start out in my bedroom and eventually go to a small apartment I'm sure they'll have all the SPL I'll need for the forseeable future.
Thanks John.
BTW - do you have any idea of the weight of the magnets on the DA175s? I'll need to video shield them. PE doesn't even know, but I'm guessing they're around 15 oz.
Zaph said:
Interesting! More advanced motor, more expensive, yet somewhat inferior performance. Well, that convinces me - I'm gonna abandon the RS idea. Back to the BAMTM. Since they'll start out in my bedroom and eventually go to a small apartment I'm sure they'll have all the SPL I'll need for the forseeable future.
Thanks John.
BTW - do you have any idea of the weight of the magnets on the DA175s? I'll need to video shield them. PE doesn't even know, but I'm guessing they're around 15 oz.
Yeah... "problem" isn't really what I meant, more like at what volume level/power input level do the distortion and compression begin to become noticeable. I've also been thinking about high (clean) dynamic range lately.
I would guess as we get close to Xmax distortion would build up at some increasing rate, and that would be fairly predictable... but I don't have much of a SWAG feel for how fast the thermal builds up. Never have seen a thermal dissipation coefficent published for a speaker's voice coil...
Hmmm... could be some potential for the future, if PE redesigns the DA175 motor or adds the cone to a RS series motor... loose the stamped frame... It won't be a $18 woofer anymore, but might end up a different and worthy entry into the RS series...
Now should it get the black anodizing job, or stay silver?
Zaph said:
Hi,
Well just a suggestion:
A proper 3-way design. Not a fully BSC'd speaker with a sub added.
Possibly an unBSC'd mid/treble with BSC provided by the bass units.
But for a proper design you can choose relative amounts of BSC,
e.g. mid/treble has 2dB BSC upper mid, bass units provide another
3dB lower mid.
The reasons for this ?
Decent efficiency from a good midrange driver.
A good explanation of the issues involved in 3-ways.
Some of us don't have HT recievers, just stereo amplifiers....
Slim tower wise I'd go for high twin side mounted bass units
mounted resiliently in force cancelling mode, mid treble built
into a triangular section in the top.
/sreten.
Re: Re: Re: John K. - Dayton DA/RS Question
Well, I wouldn't say the RS series has inferior performance. They perform better, but with some limitations on their usefull range and they are a little more difficult to work with. A fair trade, IMHO. I'm a fan of the RS drivers also. I've got 16 of them in my closet of various sizes.
I'd estimate the DA175 magnet at around 20 oz. The real issue if adding a bucking magnet is clearing the bump on the rear plate. I don't have that dimension but I'll take a look the next time I open up my DA175 system.
I'm not the biggest fan of traditional 3-way speakers. I've done a bunch, and aside from the limits of bass output and extension, I prefer 2-ways. Mainly, I don't like the sound of crossover phase wrap right in the lower midrange. A 2-way or 2-way+sub displays less of this issue and a more cohesive upper midbass/lower midrange. Of course, that's just personal preference, no knock on those who prefer 3-ways. My listening room sports only a 2 channel amp - running only 2.5 way speakers with no sub.
One of the speakers I've had in the works for a long time (over a year) is a 50" tall and slim 3.5-way floor standing tower. (6 drive units) It addresses a few things I've come to dislike about 3-ways. I'm not going to expose too many details about it at this point, because there's no point in stirring up interest for something that could easily be another year away from finishing. Those outside the US probably won't be a fan of this system anyway since it uses all Dayton drivers except for the tweeter.
sdclc126 said:
Well, I wouldn't say the RS series has inferior performance. They perform better, but with some limitations on their usefull range and they are a little more difficult to work with. A fair trade, IMHO. I'm a fan of the RS drivers also. I've got 16 of them in my closet of various sizes.
I'd estimate the DA175 magnet at around 20 oz. The real issue if adding a bucking magnet is clearing the bump on the rear plate. I don't have that dimension but I'll take a look the next time I open up my DA175 system.
sreten said:
I'm not the biggest fan of traditional 3-way speakers. I've done a bunch, and aside from the limits of bass output and extension, I prefer 2-ways. Mainly, I don't like the sound of crossover phase wrap right in the lower midrange. A 2-way or 2-way+sub displays less of this issue and a more cohesive upper midbass/lower midrange. Of course, that's just personal preference, no knock on those who prefer 3-ways. My listening room sports only a 2 channel amp - running only 2.5 way speakers with no sub.
One of the speakers I've had in the works for a long time (over a year) is a 50" tall and slim 3.5-way floor standing tower. (6 drive units) It addresses a few things I've come to dislike about 3-ways. I'm not going to expose too many details about it at this point, because there's no point in stirring up interest for something that could easily be another year away from finishing. Those outside the US probably won't be a fan of this system anyway since it uses all Dayton drivers except for the tweeter.
Hey Zaph. Great design as always.
I was just wondering how much different the vertical lobing would be for this MTM with such a low crossover point vs something closer to 1.8-2KHz.
Clearly the lower the crossover point the better, but I was thinking of doing a similar design with another tweeter which can't cross that low.
Eric
I was just wondering how much different the vertical lobing would be for this MTM with such a low crossover point vs something closer to 1.8-2KHz.
Clearly the lower the crossover point the better, but I was thinking of doing a similar design with another tweeter which can't cross that low.
Eric
I may have to pick up a DA175
I'd like to make a couple comments.
I've been looking over Zaph's measurements again and trying to reconcile them with my own.
For the most part, my measurements and Zaphs seem to agree. Occasionally they differ. I've been trying to pinpoint the cause of that difference.
What seems to happen is that the SL style 3 toneburst measurements seem to overemphasize the low frequency distortion characteristics of the motor. Even when the test frequency is centered well outside of the bass range. (Incidentally, that's why ribbons do so much more poorly in those tests and why I fried multiple ribbon element using 4k signals...)
So you can infer from Zaph's tests partly by comparing low frequency HD patterns how a driver will do. Though I haven't tested the DA175 yet, I suspect it will not perform nearly as well as the RS180 due to the generally inferior comparative performance below 100 shown on Zaph's site.
I would argue there isn't much doubt that the RS180 is a lower distortion motor. However, it does take some crossover work to get the most out of it--if you look at the modula MT/MTM's, or, for the RS225, my xover. Not for the minimalist.
I think my site is down right now. I gotta get a real site--you have to pay for those...
I'd like to make a couple comments.
I've been looking over Zaph's measurements again and trying to reconcile them with my own.
For the most part, my measurements and Zaphs seem to agree. Occasionally they differ. I've been trying to pinpoint the cause of that difference.
What seems to happen is that the SL style 3 toneburst measurements seem to overemphasize the low frequency distortion characteristics of the motor. Even when the test frequency is centered well outside of the bass range. (Incidentally, that's why ribbons do so much more poorly in those tests and why I fried multiple ribbon element using 4k signals...)
So you can infer from Zaph's tests partly by comparing low frequency HD patterns how a driver will do. Though I haven't tested the DA175 yet, I suspect it will not perform nearly as well as the RS180 due to the generally inferior comparative performance below 100 shown on Zaph's site.
I would argue there isn't much doubt that the RS180 is a lower distortion motor. However, it does take some crossover work to get the most out of it--if you look at the modula MT/MTM's, or, for the RS225, my xover. Not for the minimalist.
I think my site is down right now. I gotta get a real site--you have to pay for those...
"Crossover Phase Wrap"
"I'm not the biggest fan of traditional 3-way speakers. I've done a bunch, and aside from the limits of bass output and extension, I prefer 2-ways. Mainly, I don't like the sound of crossover phase wrap right in the lower midrange. A 2-way or 2-way+sub displays less of this issue and a more cohesive upper midbass/lower midrange. Of course, that's just personal preference, no knock on those who prefer 3-ways. My listening room sports only a 2 channel amp - running only 2.5 way speakers with no sub."
John - could you please describe phase wrap - it's the first time I've heard the term. What exactly does it sound like, and how does a 2-way + sub reduce it? I've always thought that a 2-way plus sub (stereo) is just another type of 3-way - afterall, you're using three drivers to cover the spectrum; but as usual I suspect that's too simplistic.
I'm interested in doing stereo subs such as described for the BAMTMs - is it the fact that the subs are active/self-powered that makes the difference, or using a lower XO point? And are there any mods needed for the sub-to-satellite XO to get everything balanced, or do I just hook up the satellites to the speaker outs on the sub amp? (Naw - can't be - THAT'S too simplistic too! )
"I'm not the biggest fan of traditional 3-way speakers. I've done a bunch, and aside from the limits of bass output and extension, I prefer 2-ways. Mainly, I don't like the sound of crossover phase wrap right in the lower midrange. A 2-way or 2-way+sub displays less of this issue and a more cohesive upper midbass/lower midrange. Of course, that's just personal preference, no knock on those who prefer 3-ways. My listening room sports only a 2 channel amp - running only 2.5 way speakers with no sub."
John - could you please describe phase wrap - it's the first time I've heard the term. What exactly does it sound like, and how does a 2-way + sub reduce it? I've always thought that a 2-way plus sub (stereo) is just another type of 3-way - afterall, you're using three drivers to cover the spectrum; but as usual I suspect that's too simplistic.
I'm interested in doing stereo subs such as described for the BAMTMs - is it the fact that the subs are active/self-powered that makes the difference, or using a lower XO point? And are there any mods needed for the sub-to-satellite XO to get everything balanced, or do I just hook up the satellites to the speaker outs on the sub amp? (Naw - can't be - THAT'S too simplistic too!
)
Re: "Crossover Phase Wrap"
You may want to consider a 2.5-way TMM in that case. The BAMTM's lobing pattern looks like this. The red nulls (at 1kHz) come from the woofer to woofer spacing and will always be there in an MTM design. If you were to cross at 2kHz however, there would be another null shown at the blue line, which is 2kHz vertical. The null at that frequency would form a much narrower vertical lobe, probably by 10 or 15 degrees.
My HD plots are relatively harder to read below 100 hz because the response is not equalized to flat. That throws a variable in there that makes them harder to compare. I think most of the useful information in these plots is above 100hz, and I'd sooner point people to your measurements for a better idea of the low end.
Bohdan expressed interest in putting some work into a dedicated distortion testing app in a forthcoming (next hopefully) SE version that will improve the usefulness a lot.
Note: Friedribbons.com is available for you. Seriously, if you're going to get a web host, send me an email. The one I use is fast, cheap, with lots of bandwidth and a unbeatable feature set.
Crossover phase wrap - An LR4 crossover has 360 degrees of phase wrap, an LR2 has 180 degrees, etc. A 2-way plus sub is essentially a 3-way but with a lower than normal crossover point. The lower the crossover point, the more that wrap is pushed out of the range where most of the music is - 200-1Khz.
The audibility of phase wrap is something that is debated. However, some controlled nearfield experiments can show you just how audible it is and what it sounds like. (it's difficult to put into subjective terms) If the power response differences are taken out of the equation, lower phase wrap is what makes a shallower slope crossover sound better than a steeper one.
I haven't done much investigation into the audibility of phase wrap in elliptical crossovers so I can't comment on that, but I've done lots of 2nd order vs 4th order testing.
eyeh said:
You may want to consider a 2.5-way TMM in that case. The BAMTM's lobing pattern looks like this. The red nulls (at 1kHz) come from the woofer to woofer spacing and will always be there in an MTM design. If you were to cross at 2kHz however, there would be another null shown at the blue line, which is 2kHz vertical. The null at that frequency would form a much narrower vertical lobe, probably by 10 or 15 degrees.
ucla88 said:So you can infer from Zaph's tests partly by comparing low frequency HD patterns how a driver will do. Though I haven't tested the DA175 yet, I suspect it will not perform nearly as well as the RS180 due to the generally inferior comparative performance below 100 shown on Zaph's site.
I would argue there isn't much doubt that the RS180 is a lower distortion motor. However, it does take some crossover work to get the most out of it--if you look at the modula MT/MTM's, or, for the RS225, my xover. Not for the minimalist.
I think my site is down right now. I gotta get a real site--you have to pay for those...
My HD plots are relatively harder to read below 100 hz because the response is not equalized to flat. That throws a variable in there that makes them harder to compare. I think most of the useful information in these plots is above 100hz, and I'd sooner point people to your measurements for a better idea of the low end.
Bohdan expressed interest in putting some work into a dedicated distortion testing app in a forthcoming (next hopefully) SE version that will improve the usefulness a lot.
Note: Friedribbons.com is available for you.
Seriously, if you're going to get a web host, send me an email. The one I use is fast, cheap, with lots of bandwidth and a unbeatable feature set.sdclc126 said:John - could you please describe phase wrap - it's the first time I've heard the term. What exactly does it sound like, and how does a 2-way + sub reduce it? I've always thought that a 2-way plus sub (stereo) is just another type of 3-way - afterall, you're using three drivers to cover the spectrum; but as usual I suspect that's too simplistic.
I'm interested in doing stereo subs such as described for the BAMTMs - is it the fact that the subs are active/self-powered that makes the difference, or using a lower XO point? And are there any mods needed for the sub-to-satellite XO to get everything balanced, or do I just hook up the satellites to the speaker outs on the sub amp? (Naw - can't be - THAT'S too simplistic too!
Crossover phase wrap - An LR4 crossover has 360 degrees of phase wrap, an LR2 has 180 degrees, etc. A 2-way plus sub is essentially a 3-way but with a lower than normal crossover point. The lower the crossover point, the more that wrap is pushed out of the range where most of the music is - 200-1Khz.
The audibility of phase wrap is something that is debated. However, some controlled nearfield experiments can show you just how audible it is and what it sounds like. (it's difficult to put into subjective terms) If the power response differences are taken out of the equation, lower phase wrap is what makes a shallower slope crossover sound better than a steeper one.
I haven't done much investigation into the audibility of phase wrap in elliptical crossovers so I can't comment on that, but I've done lots of 2nd order vs 4th order testing.
Re: Re: Re: Re: John K. - Dayton DA/RS Question
Hi,
Great ! just the man for the job. A healthy dose of reality and the
realisation that most 3-ways don't work very well is whats needed
when you do want decent sensitivity from a single mid and lots of
bass output and extension.
Far better than someone who can't see the problems.
The sort of 3-way I'm thinking of does not have the phase wrap
you describe as the bass mid / crossover is a lower order overlap
(the mid has minimal BSC). The mid would use a sealed box roll-off
(highish Q) which though it doesn't work well with a 1st order
parallel c/o it could work well with a 1st order series bass/mid c/o.
The BSC rise on the the bass units needs to be clobbered but
enough output left to fill in the lack of BSC in the mid unit, I haven't
simmed this but I suspect a form of second order would be needed.
This sort of c/o allowing higher mid / treble sensitivity is not easy
to do with an active sub, and overall the bass / mid integration
is phasewise better than active LR2 or LR4 at a lowish frequency.
Just a thought though.........., if your not keen, your not keen.
//sreten.
Zaph said:
Hi,
Great ! just the man for the job. A healthy dose of reality and the
realisation that most 3-ways don't work very well is whats needed
when you do want decent sensitivity from a single mid and lots of
bass output and extension.
Far better than someone who can't see the problems.
The sort of 3-way I'm thinking of does not have the phase wrap
you describe as the bass mid / crossover is a lower order overlap
(the mid has minimal BSC). The mid would use a sealed box roll-off
(highish Q) which though it doesn't work well with a 1st order
parallel c/o it could work well with a 1st order series bass/mid c/o.
The BSC rise on the the bass units needs to be clobbered but
enough output left to fill in the lack of BSC in the mid unit, I haven't
simmed this but I suspect a form of second order would be needed.
This sort of c/o allowing higher mid / treble sensitivity is not easy
to do with an active sub, and overall the bass / mid integration
is phasewise better than active LR2 or LR4 at a lowish frequency.
Just a thought though.........., if your not keen, your not keen.
//sreten.Alright guys, I have finished the enclosures, crossovers are completed so I will post pics tonight after work. First up, I am going to try the 2 cu ft sealed.
First question, how much accousti-stuff per cubic ft is needed in a sealed enclosure?
Second, as for "breaking in drivers" do I play test tones, cd's, etc? And how long for the break in period?
Finally, any issues if I mount the port on the front baffle? Since I have the removable baffle, and this is a "test" enclosure with adjustable shelf braces for varying volumes I'd like to avoid a port on the back.
First question, how much accousti-stuff per cubic ft is needed in a sealed enclosure?
Second, as for "breaking in drivers" do I play test tones, cd's, etc? And how long for the break in period?
Finally, any issues if I mount the port on the front baffle? Since I have the removable baffle, and this is a "test" enclosure with adjustable shelf braces for varying volumes I'd like to avoid a port on the back.
A couple completed pics of the enclosure.....still need to wire up 1 speaker, adjust a couple hurricane nuts, maybe add a little gasket tape and the list goes on........
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
outfitter said:
The first question is tough because I don't have much of a concept of weight when it comes to fiber stuffing. Just make it a little more dense near the bottom, and leave a good 4-6" of space behind the driver. If you got the 1# bags of Acousta-Stuf from madisound, I'd estimate 4 bags. If you didn't get that much, you could always just use dacron at the bottoms.
Most don't put the port on the baffle so midrange escapes out the back, but in all honesty it doesn't matter as much as you'd think and out the front would be fine.
outfitter said:
Very nice work, it looks professional.
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