The PHL 930, like the BMS 5S117 seems to a have a bit more flat cone and surround profile than most. I'm just assuming that's good for maintaining wider radiation somewhat further out. (Though the Sd is a bit larger for the PHL, in theory at least could imply narrowing at a lower frequency, but don't know by how much really. Personally I like the flat dustcap on the BMS and the mechanical designs seems like it'd be a bit more flush on the baffle.) The BMS has a longer coil, its mathematical Xmax is (15-5)/2=5 and (12 -6)/2=3 on the PHL.
Here's an attempt with lowering the xo to 180Hz and using the the driver's low-end roll-off and a 1st order HPF on top to cross the mid. Closed box sim says Fb=137 Qtc=0.55 in 3l for the BMS 5S117. The first 2nd order filter is meant to represent that, i.e. the driver's roll-off, and there's the 186Hz 1st order HPF on top (could be a cap). The filter limits the excursion to 1/2 at high SPL. Referring back to the BMS datasheet, it's around 250Hz where the distortion really takes off, trying to estimate it with the sim, that would correspond to 1.8mm excursion. With the filter the highest it reaches is 2.5mm at 125Hz, that would correspond to 190Hz without filter and on the datasheet the distortion is already very elevated there, on the other hand this is 109dB SPL in the mid-band and I think even a 12" would be limited to match that in the sub-bass? With lowering the xo frequency to 180Hz the excess GD below 100Hz isn't any better anymore than with LR4 at 300Hz, but above it's better.
Looking at this again, when I look at the curve of the mid driver with LR2 at 300Hz, I kinda don't like how it looks like it is covering not a lot of bandwidth on the lower end and it's like the bass driver extends up too high.
Here's an attempt with lowering the xo to 180Hz and using the the driver's low-end roll-off and a 1st order HPF on top to cross the mid. Closed box sim says Fb=137 Qtc=0.55 in 3l for the BMS 5S117. The first 2nd order filter is meant to represent that, i.e. the driver's roll-off, and there's the 186Hz 1st order HPF on top (could be a cap). The filter limits the excursion to 1/2 at high SPL. Referring back to the BMS datasheet, it's around 250Hz where the distortion really takes off, trying to estimate it with the sim, that would correspond to 1.8mm excursion. With the filter the highest it reaches is 2.5mm at 125Hz, that would correspond to 190Hz without filter and on the datasheet the distortion is already very elevated there, on the other hand this is 109dB SPL in the mid-band and I think even a 12" would be limited to match that in the sub-bass? With lowering the xo frequency to 180Hz the excess GD below 100Hz isn't any better anymore than with LR4 at 300Hz, but above it's better.
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Tweaking it a bit, changing the LPF on the bass driver to Bessel, increasing the HPF filter frequency on the mid resulting in a xo freq of 200Hz, that 2.5mm excursion is reduced to 2mm.
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Cheers. Thanks for the advice.
I think a flat impedance is ultimately what I want. (i used to ignore it looking at graphs)
I agree with your idea- the mid should not play so low.
I think below 400hz GD does not matter as much as higher up. It is all SPL-based hearing that is bouncing around a small room. That is the premise that I am operating under anyways.
Most likely with a driver that has an Fs between 100hz and 200hz, it will need a steeper slope than what your sim is using.
Do you own this part? I'd love to see a GD graph. It still seems like this is a 2way part more than a 3way part.
No, I have yet to build something, but a 2-way part would have Fs around 50Hz. This one has 95Hz and in a 3l chamber the response is a high Fb=137 and a low Qtc=0.55 and both of these values are quite integral in the above example to implement the shallow 2nd 200Hz LF-MF xo, like it is, with just one additional 1st order HPF. If anything, this is a mid use case. The B&C 5MDN38 could be called a more "hard core" mid with Fs=240 but it has a lot less Xmax, it's more like for LR4 300Hz xo. This brings us to the question about GD at low frequencies.
https://www.diyaudio.com/community/threads/vituixcad.307910/page-183#post-6948950Check out this discussion. He says high GD from a steep LF-MF xo in a 3-way is bad.
The 2nd order 200Hz xo sketch has around 1.5ms excess GD at 100Hz (slowly rising from 0.5ms at 1kHz), whereas the LR4 xo at 300Hz comes with a bump in the GD as high as 2ms up at 300Hz, in my attempt at least.
Basically in an xo the damage to the GD comes from the LPF mostly. Higher order and lower cut-off frequency being more detrimental to the GD. In the case of MF-HF xo, I think 1.5kHz is high enough so that GD from LR4 can be considered fine and it attenuates the output of the cone and protects the tweeter more, a good set of features. But if you want those kind of GD values as above at lower frequencies (without using DSP), seems like a lowish 2nd order xo is the way to go. (Unless you want the large bass driver to play a more extended range, not sure that's a good idea.)
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Hi, are you simulating in hornresp, or winisd?
Dont let excursion go past 1-2mm for a midrange.
I was lured to this thread because the far field premise.
I feel that chasing high SQ with inefficient drivers is an extreme sport...like chasing high speeds up a mountain on a pedal bike and then asking the biker to pedal as hard is they could, being the farfield part
I didnt catch the actual intended listening distance but high directivity will be on your side if really, wanting far field, as well, high efficiency drivers.
When I design I look to limit the main detractor of sound quality aka excursion. Aiming for far field (10ft listening distance?) only challenges things because we loose spl over distance, so youd have to push the system harder to achieve volume.
If you limit the mids to ~100hz or higher that simplifies things I think. I didnt catch if you were using a sub(s).
The issue of high BL causing motor noise...is questionable....I've never came across this topic and dare say its disregardable advice. Higher BL does tame resonance at fs and increases efficiency...it is a good idea to stay within half xmax on the bass drivers as well. The jbl m2 woofer is one exception that I know of that has consistent BL into the range of its xmax... which is better than normal. If keeping excursion below 1-2mm I think BL is almost a null issue in particular if you stay an octave above fs...which for a dedicated mid...you should.
Simply put...things get easier/better...the more efficient the woofer/driver used and higher directivity will increase SQ for you in particular at far field.
Take as a grain of salt if I missed your objective
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My sim attempt shows it's being limited to just below 2mm at 109dB mid-band SPL, half space (so pre baffle loss). This is with a 1st order HPF around 250Hz which results in a 200Hz effective xo.
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Hi, camplo.
vcad. Right now, I am just looking at the directivity and baffle sim. Once I have a set of XO's I connect that to a box sim. I will be sure to not exceed 1-2mm. Thanks!
Yeah, that balance is what I am trying to find where the mountain is a hill and the bike is easy to pedal. I know I could just slap in a large driver and call it a day but I am also interested in a mid that has a linear GD in its operating range.
It is more of an observation based on a few graphs from one site. Just a spitball guess by a novice hobbyist. Not really advice but maybe there is a language conversion issue. Here is where I got the data:
https://www.robsandiy.com/html/mid_bass/mid_bass_tests.html
That is a pro. There are no cons of too high of a BL?
I could not find any other data about the driver.
This does back up why one should care:
https://www.researchgate.net/public...ynamic_Loudspeakers_Modelling_and_Measurement
The distance is only 2.5-3 meters. Mid 70db's at the LP is enough. Maybe low 80's to have some wiggle. So 100db-110db like @mjvbl is simulating should do. I do have a 12" sub so LF is not needed out of the mid.
Yeah, that looks just right. Thanks!
look at how BL is achieved. A combo of magnet strength and electromagnetivity...
Bigger magnet con is, weight and expense....need a lighter speaker?..
To increase Electromagnet strength we have to increase winds of wire...
This adds weight to voice coil, lowering hf ability.
So there's a balancing act of price and performance goals.
Regarding BL vs Excursion....This leads us back to driver efficiency.... with a larger driver excursion can be reduced, thus driver linearity issues are reduced.....the linearity issues come with excursion....no excursion....no nonlinearity lol....little excursion, little issue. 1-2mm? no ones complaining about nonlinearity. From what I've learned, a lot of drivers lose BL significantly past half xmax, this is a part of the non linear linearity issue you speak of, combined with, things like suspension issues as excursion pushes us farther away from dead center, stressing the driver mechanically...
Some people design towards having the least amount of correction needed thus do not desire the rising sensitivity seen in some high BL designs...
I suspect that in most designs that are not based on full-range drivers, any reduced output in HF region due to moving mass is already going to be out of passband anyway.
Again - look at real measurements to see the whole picture, not picking apart specific characteristics.
Thanks, @454Casull & @camplo. You are very helpful and patient.
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Whenever I get a bit myopic I do try to explore the opposite extremes. There is a large driver with a high Bl for a pick. I have not made a sim yet though.
I thought the low BL + low MMS was a way to get what I want but bigger might do it. A flat decay 500hz on down is desirable. The 8" PHL mid seems to do it better than the low MMS visaton ti 100.
from zaph:
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I did some sims based on params and second-order filters at 150hz with a q=0.5. It seems like I can get a 300hz 1ms GD but not at 100hz. I am assuming once I sim the baffle and add more filters this will look worse.
SPL before excursion with the xo.
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Ok, so I might buy mids of various sizes just to hear and measure them in the hope of finding something that works for me.
so far the visaton 130m is ordered.
I contacted Visaton, bms, PHL audio, manacor, sb acoustics, and a many more with some questions. Only Visaton, PHL audio, Dynaudio, Kartesian, and SB A replied. Guess who won't be getting my cash? The shocker was the USA-based MISCO ignoring me. Even Dynaudio gave me a reply and they don't really directly sell (but did give me a quote).
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Whenever I get a bit myopic I do try to explore the opposite extremes. There is a large driver with a high Bl for a pick. I have not made a sim yet though.
I thought the low BL + low MMS was a way to get what I want but bigger might do it. A flat decay 500hz on down is desirable. The 8" PHL mid seems to do it better than the low MMS visaton ti 100.
from zaph:
...
I did some sims based on params and second-order filters at 150hz with a q=0.5. It seems like I can get a 300hz 1ms GD but not at 100hz. I am assuming once I sim the baffle and add more filters this will look worse.
SPL before excursion with the xo.
..
I agree: no param is better than a real measurement. It is just a fuzzy starting point and I have to trust a manufacturer to be consistent.
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Ok, so I might buy mids of various sizes just to hear and measure them in the hope of finding something that works for me.
so far the visaton 130m is ordered.
I contacted Visaton, bms, PHL audio, manacor, sb acoustics, and a many more with some questions. Only Visaton, PHL audio, Dynaudio, Kartesian, and SB A replied. Guess who won't be getting my cash? The shocker was the USA-based MISCO ignoring me. Even Dynaudio gave me a reply and they don't really directly sell (but did give me a quote).
I take back my MISCO rant- they sent a great reply. I just needed to wait a bit longer (i am the worst at waiting). To be fair, I did email them last fri and the rest way before.
The xbl2 drivers look like a good fit- they can play 900hz-150hz. The 4" cone has a GD that looks like the 2" visaton dome. I will be sure to make a MISCO 3way sim.
The xbl2 drivers look like a good fit- they can play 900hz-150hz. The 4" cone has a GD that looks like the 2" visaton dome. I will be sure to make a MISCO 3way sim.
That isn't a crossover though but minimum phase amplitude curves and their "corresponding" group delay curves. If you would shape the amplitude response (with filters or anything) of any two drivers you would get the same GD. In the kind of LF-MF crossover we're discussing the big excess GD contribution is going to come from the LPF of the lower band, and also a much more rising GD below 100Hz (compared to those curves, that is how it is) from the lower roll-off of the bass driver. (Also chances are you can't get flat summing with a shallow (2nd order) LPF on the bass if you're applying a 2nd order filter on top of the mid's roll-off.) As far as GD of 2nd order roll-offs, the best group delay comes from Q=0.577 (Bessel). You can see this Q target in my sketch above: the LPF on the bass driver is Bessel, as well as the sealed response of the 5S117, and the filter on top of that is 1st order.
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The GD does shift based on the box size and T/S params when you connect the XO to the enclosure sim. This is what I was looking at. I am not trying to simulate a real XO. Just a fuzzy view of box sizes, T/S params, and a low XO.
I am not interested in the BMS 5S117. BMS cannot answer an email.
t/s param sim: PHL 930D in a 6L box with diff. XO's
t/s param sim: PHL 930D in 6L vs PHL 2460 in 16L (dotted) with a bessel XO.
So a small mid and small box will add 1ms to 200hz using the same XO.
The PHL 2460 is my top mid-woofer pick ATM. I think going to 10" really messes up 1khz too much.
I use a 3" mid now and am happy- all of these parts are SPL overkill. But I am interested in shaving down the GD as much as I can.
t/s param sim: PHL 930D in 6L vs PHL 2460 in 16L (dotted) with a bessel XO.
So a small mid and small box will add 1ms to 200hz using the same XO.
The PHL 2460 is my top mid-woofer pick ATM. I think going to 10" really messes up 1khz too much.
I use a 3" mid now and am happy- all of these parts are SPL overkill. But I am interested in shaving down the GD as much as I can.
I found BMS to be be very responsive to technical questions. It was some time ago though.
This was the email I used contact(at)bmsspeakers.com
Thanks. I ended up buying from a diff. manufacturer. I do appreciate how BMS includes distortion measurements.
I asked a few diff. manufacturers about the country of origin for the parts. Some ignored, some gave me corporate-speak, and some (like visaton) just listed where each part was made. (the al130m is german made, dsm50 & ti100 are made in china).
....
The phl 2460 is on the way and I am jealous of some of the countries it is hopping through.
I also ordered some PE boxes and a DATS 3.
Some real measurements will help me move to the next steps.
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Got the dats 3 and the PHL 2460 all set up today.
These are my first PHL drivers. I was first shocked there was no gasket but then felt a rubber seal on the inside of the driver for the driver hole.
A phl 970 was added just to check out the 5" driver and try PHL's take on a coax. I also have a sb coax that costs 1/3 this one and will do a comparison.
+1 point to PHL for their box design kung fu. They are all one sheet just folded up.
I have done 0 break-in and the data seems to mostly agree. I've read that this data can change so I will run the drivers a few hours with some pink noise and measure again.
This is showing the TS params out of VCAD (solid red line) and the DATS3 data (dashed and dotted) all loaded into REW.
The diff between the model and real drivers in VCAD. Dotted are the real, solid is the SIM.
The data:
PHL Audio 2460_2 W Active 8 5.075 80.61 2.195 0.597 0.469 2.5 22.13 0.19 26 219 9.764 160 5.5 0 0.312 97.6 18.79
PHL Audio 2460_1 W Active 8 5.059 73.72 2.256 0.542 0.437 2.5 22.82 0.204 30 219 9.764 160 5.5 0 0.285 97.4 18.84
PHL Audio 2460 W Active 8 5.2 79 4.17 0.5 0.45 2.5 21 0.19 13.1 219 10.4 160 5.5 0 0.29 95 20.8
The top two are the real ones. This is right out of vcad's enclosure tool.. i did not capture column names. The spec CMS=4.17 VS real CMS= 2.195 and 2.256 seems intentional and 1/2 of what was promised. The VAS reflects this too with spec VAS =13L vs real VAS = 26L and 30L. I got a really close MMS; the promise was MMS=21g and I got MMS=22.13g and 22.82g.
I've never measured drivers before. This seems not too bad? Opinions?
These are my first PHL drivers. I was first shocked there was no gasket but then felt a rubber seal on the inside of the driver for the driver hole.
A phl 970 was added just to check out the 5" driver and try PHL's take on a coax. I also have a sb coax that costs 1/3 this one and will do a comparison.
+1 point to PHL for their box design kung fu. They are all one sheet just folded up.
I have done 0 break-in and the data seems to mostly agree. I've read that this data can change so I will run the drivers a few hours with some pink noise and measure again.
This is showing the TS params out of VCAD (solid red line) and the DATS3 data (dashed and dotted) all loaded into REW.
The diff between the model and real drivers in VCAD. Dotted are the real, solid is the SIM.
The data:
PHL Audio 2460_2 W Active 8 5.075 80.61 2.195 0.597 0.469 2.5 22.13 0.19 26 219 9.764 160 5.5 0 0.312 97.6 18.79
PHL Audio 2460_1 W Active 8 5.059 73.72 2.256 0.542 0.437 2.5 22.82 0.204 30 219 9.764 160 5.5 0 0.285 97.4 18.84
PHL Audio 2460 W Active 8 5.2 79 4.17 0.5 0.45 2.5 21 0.19 13.1 219 10.4 160 5.5 0 0.29 95 20.8
The top two are the real ones. This is right out of vcad's enclosure tool.. i did not capture column names. The spec CMS=4.17 VS real CMS= 2.195 and 2.256 seems intentional and 1/2 of what was promised. The VAS reflects this too with spec VAS =13L vs real VAS = 26L and 30L. I got a really close MMS; the promise was MMS=21g and I got MMS=22.13g and 22.82g.
I've never measured drivers before. This seems not too bad? Opinions?
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