I asked the same question in another thread about the WR125S and somebody helpfully pointed out the way rather simple geometry suggests an answer: at 1 foot, moving your head 6 inches to the side puts you 30 degrees off axis; at 10 feet, you're not 30 degrees off until you move 5 feet. Looked at another way, the same 6 inches puts you less than 3 degrees off axis when seated at my hypothetical 10 foot distance. That right there suggests off-axis response might be especially critical in the near field.morbo said:
It seems to me that there are other factors at play though. Depending on your listening habits, you might tend to stay in one spot at your computer such that a 6 inch sweet spot is not unreasonable. Also, in the near field the problem of power response is mostly avoided so in that sense the off-axis response as reflected from walls and ceiling needs not be a factor.
It's an interesting question, and I think more discussion could be useful for those of us wanting to build computer speakers or nearfield monitors.
morbo said:Interesting posts about the various tweeters Zaph.. I got the impression from your comments after testing that the DX19 is a pretty mediocre tweeter... it is fairly cheap here, so if it is that good, I may try that out as well. The XT19 is a bit much for me $$$ wise I think. Would crossing above 5 or 6k ameliorate the stored energy @ 4k issue much?
The other tweeter I've had my eye on (mainly because of cost) is the little Audax 10mm gold dome:
An externally hosted image should be here but it was not working when we last tested it.
It would also allow for very tight driver-driver spacing, although it would need a relatively high XO, but thats something the WR125 can help with I think
A question - if I'm listening very close, ie 1-2 feet away from the speakers, how much do I need to worry about what they do @ 30-45 deg. off axis?
For another opinion on the DX19, look here:
http://206.13.113.199/ncdiyaudio/mark/DX19/vifa_dx19.htm
His results pretty much agree with mine. The ridge at 4kHz on Mark's waterfall looks pretty scary, but he's got a whopping 40db of range on that chart. I generally only show 30 db of range, since below that energy storage issues are off the radar. Ironincally, it was my tweeter too that I borrowed to him for testing. I have several DX19's laying around since they perform decently and are cheap. Don't worry too much about the little bit of energy storage at 4Khz. There have been worse offenses in tweeters costing 5 times as much. I've been listening to these for a while, and it's a great tweeter for the price. Don't feel like you need to cross over above 4kHz on these.
I've got a few of those little audax laying around, both flanged and press fit style. They aren't very good. On one of them, I jammed a pen into the dome for no reason. That kinda says something about them.
HeatMiser's point about avoiding power response issues in the near field is a good one. In the near field, room reflections are down a ways compared to far field, where the power response contributes a lot to the tonal balance. The vertical sweet spot is what you have to worry about. With 2 way and a high crossover point, you may only have an inch or two before a big null shows up at the crossover frequency. Woofer off axis response becomes an issue also if it's not aimed directly at you. For this reason, small full range drivers work best as near field monitors. To this day I still have a pair or W3-871's at my desk.
Zaph:
Just wondering if you'd had a chance to either test or listen to any of the Seas 19/20mm tweeters? From the specs posted on the Seas web site, they look as though they could be really good, but I'm hesitant to make the jump without more information about them . . . I know that some of the 27mm non-Excel Seas tweeters have received very good reviews. The DX19 looks as though it could be a really good option, but that extra energy at 4K does disturb me . . . If I were to cross the tweeter low enough, I would guess that I would hear that extra energy. I do like the off-axis response of the Vifa though. Thanks for sharing your comments and feedback.
On side note, one thing which really strikes me in this discussion is that the proper selection of a tweeter to mate up with the WR125S will probably be really important. If everything I've heard about this mid-woofer is true, then I would guess having a really high-end tweeter is almost a requirement. The ability for the tweeter to play very low may not be the priority, but low distortion, high dispersion and excellent overall detail, balance and accuracy would probably be high riorities . . . I suppose my point is that the cheapest solution may not be the best solution.
In the prior discussion about linear phase cross-overs, I couldn't help but think about using a top mount tweeter such as the Morel MDT-44. This "should" allow for the tweeter to be "phase aligned" simply by mounting it in the correct location. Have you tested any of those by chance?
Regards,
Andy
Just wondering if you'd had a chance to either test or listen to any of the Seas 19/20mm tweeters? From the specs posted on the Seas web site, they look as though they could be really good, but I'm hesitant to make the jump without more information about them . . . I know that some of the 27mm non-Excel Seas tweeters have received very good reviews. The DX19 looks as though it could be a really good option, but that extra energy at 4K does disturb me . . . If I were to cross the tweeter low enough, I would guess that I would hear that extra energy. I do like the off-axis response of the Vifa though. Thanks for sharing your comments and feedback.
On side note, one thing which really strikes me in this discussion is that the proper selection of a tweeter to mate up with the WR125S will probably be really important. If everything I've heard about this mid-woofer is true, then I would guess having a really high-end tweeter is almost a requirement. The ability for the tweeter to play very low may not be the priority, but low distortion, high dispersion and excellent overall detail, balance and accuracy would probably be high riorities . . . I suppose my point is that the cheapest solution may not be the best solution.
In the prior discussion about linear phase cross-overs, I couldn't help but think about using a top mount tweeter such as the Morel MDT-44. This "should" allow for the tweeter to be "phase aligned" simply by mounting it in the correct location. Have you tested any of those by chance?
Regards,
Andy
ABS said:
It's been a long time since I used a Seas 3/4" dome. Too long for me to remember if it's any good or not. I'll say that I never understood why Seas discontinued the 20TFF. It looked like a better tweeter, with better surround and a hollow polepiece. If you can still get it, I'd go for that over the 19.
I didn't do any comparison yet, but I ran some quick tests of the WR125s. On the good side, what I found so far is a very smooth and low distortion midrange. There was some high frequency breakup, but it looks controllable. On the bad side, Qts was nearly 1 and efficiency was low.
I've attached some data - Frequency response, on axis and 30 degrees off axis, T/S parameters, a CSD chart and exported Z and SPL for modelers to mess with. Don't trust the drive level, but it's supposed to be 1 watt measured at 1/2 m. These are all infinite baffle measurements, so don't forget to sum in the baffle step to get a real in-box response.
In my opinion, these need a tweeter and a crossover. Also, the effective corner frequency and shaping of the baffle step compensation could help minimize the midbass peaking from high Qts. What's left is dealing with the low efficiency. It's probably fine if you have a decent power solid state amp and you use a subwoofer, but these are probably too inefficient to use as a midrange in a passive 3-way unless you double up to a MTMW or a MMTMMW or something.
I'll let you guys know when I do more complete testing and a comparison to other drivers.
Breakin was a few hours at high Xmax.
The CSD, in my opinion is very good. Yes, there are ridges, but nothing large, and notice how through the midrange the signal immediately drops off almost 20db. Measurements like this are unfortunately not very usefull unless you have a point of comparison. Hold off on judgement of the CSD until there are side by side comparisons.
But if you need a quick example of bad, here it is.
The CSD, in my opinion is very good. Yes, there are ridges, but nothing large, and notice how through the midrange the signal immediately drops off almost 20db. Measurements like this are unfortunately not very usefull unless you have a point of comparison. Hold off on judgement of the CSD until there are side by side comparisons.
But if you need a quick example of bad, here it is.
Attachments
Bob Reimer said:
Bob, thanks for the test sample. I expect to finish up testing this coming Sunday or Monday, then I can send it back. Or if you'd like, I can send the driver onwards to another person for evaluation. There's a few guys over on the Madisound forum who would love to test this driver out.
John
It looks like this driver would work nicely in a 1.5 or 2.5 way design.
This would avoid the need to apply baffle step circuit, since the driver is not very efficient. If a woofer with a first or second order filter were brought in at a frequency made to offset the falling baffle response of the enclosure, then a resonable efficiency could result. This would preferably be an active crossover which would mean bi-amping. But I think a simple passive coil could work OK.
This is what I am planning to do, and add a tweeter if needed.
I was going to use the Adire Extemis as the .5 woofer.
Now, if I could only predict in advance what the exact crossover point and slope of the .5 speaker should be. Someday I'll buy a good modelling package.
Looking at the data that Zaph posted (thanks a million !) it looks like the reponse up to 10K is pretty decent.
This would avoid the need to apply baffle step circuit, since the driver is not very efficient. If a woofer with a first or second order filter were brought in at a frequency made to offset the falling baffle response of the enclosure, then a resonable efficiency could result. This would preferably be an active crossover which would mean bi-amping. But I think a simple passive coil could work OK.
This is what I am planning to do, and add a tweeter if needed.
I was going to use the Adire Extemis as the .5 woofer.
Now, if I could only predict in advance what the exact crossover point and slope of the .5 speaker should be. Someday I'll buy a good modelling package.
Looking at the data that Zaph posted (thanks a million !) it looks like the reponse up to 10K is pretty decent.
I just received my WR125's tonight and briefly listening to them, I am extremely impressed. Yes, they do beam in the upper frequencies, but on-axis, they sound extremely good. Placing them loosely in the end of a plastic enclosure of roughly 4 liters resulted in suprisingly good bass output. Overall I am impressed. I did notice some LF distortion at what was a moderate SPL (this occurred free air). I fully agree that a 2.5 setup with a separate subwoofer or some variant of that concept such as a TMMWW, TMMW, MTMWW or MTMW configuration might be the best way to go.
Zaph: Thanks for the feedback and thoughts regarding those Seas tweeters and thank you VERY much for turning me onto those DX19 tweeters. After careful consideration of the test results, I now agree that those DX19's do look very good, especially considering their price point. I'm planning to pick up a couple . . .
I also wanted to let everyone know that the outside diameter of the metal frame of the WR125S is approximately 5" and the distance between the outer edges of the rubber surround measures approximately 4".
Zaph: Thanks for the feedback and thoughts regarding those Seas tweeters and thank you VERY much for turning me onto those DX19 tweeters. After careful consideration of the test results, I now agree that those DX19's do look very good, especially considering their price point. I'm planning to pick up a couple . . .
I also wanted to let everyone know that the outside diameter of the metal frame of the WR125S is approximately 5" and the distance between the outer edges of the rubber surround measures approximately 4".
Well, I finally got the DX19 tweeters and my PE .25 cu. ft. boxes in over the weekend. So far, I have tested the WR125S in the box both sealed and ported. The sealed version sounded very nice but not nearly as good as the ported. I am using a 2"x7.5" port which, according to WINISD, should bring the F3 in at around 50-55hz. With this setup, the bass is surprisingly good. Far better than one would ever expect from a 4.5" inch driver, and really much more like the output from a 5.5" or 6". I would point out that my 2-way Scan-Speak setup with the 7" carbon fiber woofer has much more low end authority than the WR125S, but the 4.5" driver does hold its own when in the ported configuration.
I also briefly tested the DX19 tweeter with only a 3.3uF capacitor installed. This "should" give a theoretical x-over point around 12K, but without impedance compensation in place, I'm not so sure about that. There is no question that this tweeter sounds very nice and it has amazing off-axis response. Although the 3.3uF x-over point is certainly too high.
My next step is to take measurements and begin modeling in Speaker Workshop. At the end of the day, I think these will be awesome mini-monitors.
Andy
I also briefly tested the DX19 tweeter with only a 3.3uF capacitor installed. This "should" give a theoretical x-over point around 12K, but without impedance compensation in place, I'm not so sure about that. There is no question that this tweeter sounds very nice and it has amazing off-axis response. Although the 3.3uF x-over point is certainly too high.
My next step is to take measurements and begin modeling in Speaker Workshop. At the end of the day, I think these will be awesome mini-monitors.
Andy
This driver sounds like it is amazing. I would love to pair this up with a Bohlender Neo3 tweeter (heard the NEO3 on the Bohlender A-1 and loved it), maybe even swap the 125 for the new larger extremis 6 and have no need for a subwoofer. Alas, it's all a pipedream.....I have no woodmaking experience, no soldering, no anything.
Still it is tempting to just dive in.......
Still it is tempting to just dive in.......
I've completed a comparison of 3 similar size woofers.
Seas L12 vs Dayton RS125S vs CSS WR125S
Three Quality 125mm Midwoofers
No losers in this group, these are all great woofers. Each has it's good points and bad points, but I could be happy with any of them. Note that the WR125S Qts has been updated slightly from my previously posted T/S parameters, thanks to a faulty DCR number spotted by Bob Reimer. It still is high, but not quite as high as I previously stated.
Also note this test page is temporary. I'm out of web space and I need to post another project, so I'll need to remove this soon.
Regards,
John
Seas L12 vs Dayton RS125S vs CSS WR125S
Three Quality 125mm Midwoofers
An externally hosted image should be here but it was not working when we last tested it.
No losers in this group, these are all great woofers. Each has it's good points and bad points, but I could be happy with any of them. Note that the WR125S Qts has been updated slightly from my previously posted T/S parameters, thanks to a faulty DCR number spotted by Bob Reimer. It still is high, but not quite as high as I previously stated.
Also note this test page is temporary. I'm out of web space and I need to post another project, so I'll need to remove this soon.
Regards,
John
I have now finished my center channel after going through painting hell with it. The sound is still great. The computer speakers are still pending painting, though I've glued them together now. After letting them break in for a while and extended listening, I am starting to feel that on some material they are a bit midbass heavy. Nothing major, but I will definately be doing some measurements soon, and then using the Kxproject drivers to do some EQing and eventually a crossover to a tweeter.
Yet again I find myself thanking John K for testing these drivers and providing great information! For those of us that cannot afford to try all these different drivers for a variety of reasons, this is invaluable!
Thanks for posting your impressions with the tweeter Andy, keep us posted, I havent' got the time or $$$ to follow suit just yet but I will most likely follow in your footsteps sometime soon, although with a DSP crossover instead of passive.
Yet again I find myself thanking John K for testing these drivers and providing great information! For those of us that cannot afford to try all these different drivers for a variety of reasons, this is invaluable!
Thanks for posting your impressions with the tweeter Andy, keep us posted, I havent' got the time or $$$ to follow suit just yet but I will most likely follow in your footsteps sometime soon, although with a DSP crossover instead of passive.
John:
Thanks for testing these and publishing your results. What is your take on the large amount of low frequency distortion on the WR125S. To be honest, I am surprised by it - the large xmax of the driver should be helping to reduce the linear distortion at low frequencies, but I guess it's not. On the other hand, the distortion levels about 200hz appear to be extremely good, I am guessing that this is part of the reason why the midrange clarity of this driver is so good . . . What I'm struggling with evaluating is just how much of an issue the low frequency distortion really is . . . Do you have a sense of how this driver compares to other drivers which use either a polypropylene cone or a paper cone? Perhaps what we are seeing is just a paper vs. metal cone issue. Any chance of comparing the highly regarded Vifa P13 poly cone driver too? I know it is a 5.5" (slightly larger), but I believe it also falls into this category . . .
Andrew
Thanks for testing these and publishing your results. What is your take on the large amount of low frequency distortion on the WR125S. To be honest, I am surprised by it - the large xmax of the driver should be helping to reduce the linear distortion at low frequencies, but I guess it's not. On the other hand, the distortion levels about 200hz appear to be extremely good, I am guessing that this is part of the reason why the midrange clarity of this driver is so good . . . What I'm struggling with evaluating is just how much of an issue the low frequency distortion really is . . . Do you have a sense of how this driver compares to other drivers which use either a polypropylene cone or a paper cone? Perhaps what we are seeing is just a paper vs. metal cone issue. Any chance of comparing the highly regarded Vifa P13 poly cone driver too? I know it is a 5.5" (slightly larger), but I believe it also falls into this category . . .
Andrew
454Casull is correct, I am designing a x-over for the DX19 with the WR125S. I am not looking at the XT19 mostly due to cost constraints. So far my listening impressions of the DX19 are extremely positive. The waterfall plots I've previously viewed showed some excess energy around 4K. It might be desirable to x-over above that frequency to reduce as much as possible the limited damping at that frequency. In addition, the WR125S has extremely good HF extension and so the desire to take advantage of a single driver through the mid-band to the greatest extent possible is also a desirable goal in the overall speaker design. However, this particular goal must be balanced with off-axis response as well. As the WR125S starts reaching higher frequencies, it also begins to "beam". Finding a good balance is the key.
Andy
Andy
Just wanna say thanx to John (Zaph) for providing us with the
Three Quality 125mm Midwoofers which i found very useful for
pre-evaluating all three mids.
I was just curious if theres is other measured data on the off-axis
of these three babies for referrence.
especially those done by John would be great as to compliment his previous measurements
Three Quality 125mm Midwoofers which i found very useful for
pre-evaluating all three mids.
I was just curious if theres is other measured data on the off-axis
of these three babies for referrence.
especially those done by John would be great as to compliment his previous measurements
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