Hi,
I want to build a three way passive kind-of-SCM100-monitor using the ATC SM75 and (probably) the DXT tweeter, since I already know and have both (and might also be able to control off-axis dispersion). I aim to cross (-6dB) a little above 400 and around 2800Hz. Yet, I am wondering which woofer to use.
My two candidates are the ATC SB75-314 - which would somehow appear to fit to and ATC project... - or the PHL B30-4021 - which was rumoured to be used by Klein+Hummel in their o500.
Both would allow tuning between 30 and 35 Hz in 80-100l, which would be fine for me.
What are your thoughts on these ideas? Would you prefer another woofer? Thanks for sharing your comments!
Best regards,
Leif
I want to build a three way passive kind-of-SCM100-monitor using the ATC SM75 and (probably) the DXT tweeter, since I already know and have both (and might also be able to control off-axis dispersion). I aim to cross (-6dB) a little above 400 and around 2800Hz. Yet, I am wondering which woofer to use.
My two candidates are the ATC SB75-314 - which would somehow appear to fit to and ATC project... - or the PHL B30-4021 - which was rumoured to be used by Klein+Hummel in their o500.
Both would allow tuning between 30 and 35 Hz in 80-100l, which would be fine for me.
What are your thoughts on these ideas? Would you prefer another woofer? Thanks for sharing your comments!
Best regards,
Leif
Too soft and not in the right sense...
There are many possible speakers.
For exemple, you can go with this peculiar one :
- Volt RV3143
Other candidate, very capable but a bit ugly :
- Beyma 12lx60v2.
A luxurious one with imperceptible distortions up to 600hz.. :
- AudioTechnology 12D77Kap (in a 75 liters ported @ 25hz ) or a 10C77KAP
or an other approach :
- One pair per box of this new Satori WO24P-8 connected in parallel but each one in a closed volume of approximately 42/43 liters.
+1 for the SB34NRXL75-8 ...A real-woofer with an advanced low Le motor. 91db sensitivity should blend well with the 89db sensitivity of the ATC 150.
=========
Troels Gravesen has measurements for the ATC 150, and suggests a simple LR2/LR2 2nd order high-pass filter will produce a 4th roll-off, and at the top a true 2nd order low-pass filter can be achieved.
ATC-SM75-150
=============
The ATC designs include crossover notch filters for some break-up modes which appear around 4.5 kHz. ATC literature discusses how the tweeter was selected to have a similar polar dispersion around the crossover frequency. I attached Troels polar data to illustrate this challenge.
=========
Troels Gravesen has measurements for the ATC 150, and suggests a simple LR2/LR2 2nd order high-pass filter will produce a 4th roll-off, and at the top a true 2nd order low-pass filter can be achieved.
ATC-SM75-150
=============
The ATC designs include crossover notch filters for some break-up modes which appear around 4.5 kHz. ATC literature discusses how the tweeter was selected to have a similar polar dispersion around the crossover frequency. I attached Troels polar data to illustrate this challenge.
Attachments
Thank you for your replies!
- I wanted to stick closely to ATC's crossover - as posted - so it's not 6dB/octave but -6dB point.
- thanks for sharing the illustration of the selection of the Vifa tweeter, I haven't known it. While I do not consider the DXT to be the perfect choice, it may actually work well. Here are data of the DXT with a Wavecor 5,5'' - I think the horizontal sonogram looks very good, and a similar baffle layout using the ATC may result in a comparable result.
DXT-MON – Heißmann Acoustics
Concerning the low-end:
- I thought about the Volt - but don't know, whether the Volt will outplay the ATC. I was talking once to wilmslow audio concerning this matter, and my impression was they like both equally.
- Thanks for suggesting the Audiotechnology, which appears to have a easy to cross frequency response as far as I found data.
- I have to think about the SB speakers - I like the idea of two Satori MO24 in a smaller baffle, but it may (need to) end in a 3.5 way. They also appear to work in a reflex enclosure of about 130l (64l each) resulting in a "real" floor standing box. Do you think, the SB34NRX will be "as black" as the ATC?
I may have to add, that I am presently listening to an active system using the ATC SB75-234 SC in 50l 35Hz (with exceptional sonics I can hardly believe...), ATC mid and the ScanSpeak Beryllium Revelator, and before the ATC mid was combined with the PHL B30-4531(which had a little more bang... but doesnt work that good in a passive system w/o equalizing) and the Mundorf UM164 2.1 AMT, which was THE mid/ high combination I have encountered so far. I was therefore mainly thinking about ATC or PHL again... This time, the speaker will be for a larger room.
Thanks so far for your comments!
Best
Leif
- I wanted to stick closely to ATC's crossover - as posted - so it's not 6dB/octave but -6dB point.
- thanks for sharing the illustration of the selection of the Vifa tweeter, I haven't known it. While I do not consider the DXT to be the perfect choice, it may actually work well. Here are data of the DXT with a Wavecor 5,5'' - I think the horizontal sonogram looks very good, and a similar baffle layout using the ATC may result in a comparable result.
DXT-MON – Heißmann Acoustics
Concerning the low-end:
- I thought about the Volt - but don't know, whether the Volt will outplay the ATC. I was talking once to wilmslow audio concerning this matter, and my impression was they like both equally.
- Thanks for suggesting the Audiotechnology, which appears to have a easy to cross frequency response as far as I found data.
- I have to think about the SB speakers - I like the idea of two Satori MO24 in a smaller baffle, but it may (need to) end in a 3.5 way. They also appear to work in a reflex enclosure of about 130l (64l each) resulting in a "real" floor standing box. Do you think, the SB34NRX will be "as black" as the ATC?
I may have to add, that I am presently listening to an active system using the ATC SB75-234 SC in 50l 35Hz (with exceptional sonics I can hardly believe...), ATC mid and the ScanSpeak Beryllium Revelator, and before the ATC mid was combined with the PHL B30-4531(which had a little more bang... but doesnt work that good in a passive system w/o equalizing) and the Mundorf UM164 2.1 AMT, which was THE mid/ high combination I have encountered so far. I was therefore mainly thinking about ATC or PHL again... This time, the speaker will be for a larger room.
Thanks so far for your comments!
Best
Leif
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Crossover around 400Hz = 32" wavelength => 8" quarter wavelength
A single 12" woofer mounted close to the ATC-150, but less than 24" height(25% of 96" ceiling) for some control of floor bounce would get my initial simulation work. ATC engineers use only one woofer mounted just below the ATC-150 on their best designs(pic). For baffle diffraction control, the better ATC speakers use large radius rounds, and Avalon-style cabinets use the truncated pyramid with deep bevels.
Since the ATC-150 has ~89db sensitivity, and deep "black" bass is desired, one 12" woofer with modest Mms plus a low inductance motor supporting the required 400Hz crossover seems a good choice after baffle step loss is considered. A real-woofer with low Fs and medium Qtc for good bass, but a wide-bandwidth motor and cone design for the 400Hz crossover. This 12" woofer will cover a large portion(80-400) of the vocal range.
To remove any 12" cone breakup, a 400Hz BW3 or LR4 acoustic slope crossover between the 12" woofer and ATC-150 would get my initial simulation work.
A speaker using a lower bass crossover frequency ~120-200Hz would be a better long wavelength match for two front woofers, even two side-side woofers, since the polar mess from baffle step and floor effects would be merged into one crossover with equalization.
========== B&W has excellent engineers ===========
B&W Nautilus 800 White Paper: “One remarkable fact was consistently noticed during the development of the new 380mm bass unit for the Nautilus™801, and that was that a single large and stiff bass cone always sounded better than a number of smaller cones, even though they may well have had the same aggregated properties. One possible explanation for this is the concept of the production of a “coherent wave front”. This will be produced by a single large very stiff cone, which can couple with the air in a uniform manner over the whole of its surface area unaffected by differences in loading over that area. This behavior is to be compared with that of several cones which, even though they may be closely spaced, will still leave gaps of “uncoupled air” between them. The very stiff cone material of the large single driver, which is a thick sandwich of Kevlar® reinforced paper fibers with a very stiff skin, makes it less responsive to local changes of acoustic impedance or unbalanced modal pressures either behind or in front of the cone.”
A single 12" woofer mounted close to the ATC-150, but less than 24" height(25% of 96" ceiling) for some control of floor bounce would get my initial simulation work. ATC engineers use only one woofer mounted just below the ATC-150 on their best designs(pic). For baffle diffraction control, the better ATC speakers use large radius rounds, and Avalon-style cabinets use the truncated pyramid with deep bevels.
Since the ATC-150 has ~89db sensitivity, and deep "black" bass is desired, one 12" woofer with modest Mms plus a low inductance motor supporting the required 400Hz crossover seems a good choice after baffle step loss is considered. A real-woofer with low Fs and medium Qtc for good bass, but a wide-bandwidth motor and cone design for the 400Hz crossover. This 12" woofer will cover a large portion(80-400) of the vocal range.
To remove any 12" cone breakup, a 400Hz BW3 or LR4 acoustic slope crossover between the 12" woofer and ATC-150 would get my initial simulation work.
A speaker using a lower bass crossover frequency ~120-200Hz would be a better long wavelength match for two front woofers, even two side-side woofers, since the polar mess from baffle step and floor effects would be merged into one crossover with equalization.
========== B&W has excellent engineers ===========
B&W Nautilus 800 White Paper: “One remarkable fact was consistently noticed during the development of the new 380mm bass unit for the Nautilus™801, and that was that a single large and stiff bass cone always sounded better than a number of smaller cones, even though they may well have had the same aggregated properties. One possible explanation for this is the concept of the production of a “coherent wave front”. This will be produced by a single large very stiff cone, which can couple with the air in a uniform manner over the whole of its surface area unaffected by differences in loading over that area. This behavior is to be compared with that of several cones which, even though they may be closely spaced, will still leave gaps of “uncoupled air” between them. The very stiff cone material of the large single driver, which is a thick sandwich of Kevlar® reinforced paper fibers with a very stiff skin, makes it less responsive to local changes of acoustic impedance or unbalanced modal pressures either behind or in front of the cone.”
Attachments
Thanks LineSource! So you would be OK with the SB acoustics 34 and save the money for the ATC 314 bass?
Thanks, Leif
Thanks, Leif
I have never heard an ATC 12" woofer... from what I have read, you would want to study the SB75-314-SC 12" woofer which has spec 89db sensitivity, 74gMms, Fs=23hz. ATC also describes an impossible to buy SB75-315-SL. SL = short coil, super linear motor(copper shorting rings for low inductance), which ATC uses in its top audiophile 3-way speakers.
According to ATC, their SB75-314 SC 12” woofer with Short Coil (long gap) has a magnet gap height of 20mm and a coil length of 10mm. This means a linear Xmax of +/- 5mm from the underhung motor. It has a swept area of 550cm2. This means it’ll displace 0.55L of air peak-to-peak while maintaining linearity.
The 91db sensitivity 12" SB34NRXL75-8 has a overhung motor with a linear 10mm Xmax, 2x the ATC woofer.
I suspect that both woofers are a good match for the ATC-150. Crossover sims might help you decide.
According to ATC, their SB75-314 SC 12” woofer with Short Coil (long gap) has a magnet gap height of 20mm and a coil length of 10mm. This means a linear Xmax of +/- 5mm from the underhung motor. It has a swept area of 550cm2. This means it’ll displace 0.55L of air peak-to-peak while maintaining linearity.
The 91db sensitivity 12" SB34NRXL75-8 has a overhung motor with a linear 10mm Xmax, 2x the ATC woofer.
I suspect that both woofers are a good match for the ATC-150. Crossover sims might help you decide.
I do not want to insist but I strongly advise against the use of the SB34NRXL75-8...
Take a look at the diy section of the French forum "HCFR" and you will understand that it is not really made for the use you want to make of it ...
It would seem that the engine is completely sub-dimentioned for the weight of the menbrane.
Take a look at the diy section of the French forum "HCFR" and you will understand that it is not really made for the use you want to make of it ...
It would seem that the engine is completely sub-dimentioned for the weight of the menbrane.
I am using the Scanspeak Revelator 32W/8878T01 8 ohm 13" with the ATC 16 ohm mid. The former is in a separate 110 litre reflex box tuned to 17Hz. Tweeter is Scanspeak revelator. The bass crosses at 390Hz and has a 2nd order HP. It measures well and sounds good to me.
I don't think so. I found these rounds and chamfers are acoustically not very relevant. Or, as Siegfried Linkwitz wrote "With most speaker cabinets the radius or chamfer is acoustically too small and is primarily cosmetic."
German company AOS has some designs with the ATC midrange, combined with Scanspeak and ATC woofers:
Scan-Speak
Scan-Speak
I'd rather see some evidence supporting such a claim. Strangely though, an XL motor and weak at the same time.
The Scan Speak 32W8878T is one of the best low Fs woofers available. Put it on your list.
In the USA, the 89db Scan Speak 32W8878T is $560 and the 91db SB34NRXL75-8 is $242
Do you plan to use a 400Hz LR2/LR2 acoustic crossover for the mid-woof? Cone breakup near 800Hz needs consideration. You may need steeper slope crossovers with some woofers.
-------------
-Volt RV3143 SPL drops fast at 600Hz, and has Fs = 35 Hz, Qt=0.3, so you will not get deep "black" bass with a passive Xover.
-Beyma 12lx60v2 has Fs = 49Hz .... not a woofer
Please post: SPL measurements for the ATC SB75-314 SC
With a 0.5" router, you can put 1.5" radius edge rounds on your front baffle.
In the USA, the 89db Scan Speak 32W8878T is $560 and the 91db SB34NRXL75-8 is $242
Do you plan to use a 400Hz LR2/LR2 acoustic crossover for the mid-woof? Cone breakup near 800Hz needs consideration. You may need steeper slope crossovers with some woofers.
-------------
-Volt RV3143 SPL drops fast at 600Hz, and has Fs = 35 Hz, Qt=0.3, so you will not get deep "black" bass with a passive Xover.
-Beyma 12lx60v2 has Fs = 49Hz .... not a woofer
Please post: SPL measurements for the ATC SB75-314 SC
With a 0.5" router, you can put 1.5" radius edge rounds on your front baffle.
Attachments
Hi there,
I always wondered if the 3" ATC (or Volt) dome could be paired to a TAD TM-1201H since this is the mid-woofer I have and I personally love the ATC/Volt domes. I have read elsewhere the 3" dome is better if used from 600Hz up, a frequency not difficult to handle for the TAD mid-woofer.
This would be of course a 4-way system.
Regards,
Claudio.
I always wondered if the 3" ATC (or Volt) dome could be paired to a TAD TM-1201H since this is the mid-woofer I have and I personally love the ATC/Volt domes. I have read elsewhere the 3" dome is better if used from 600Hz up, a frequency not difficult to handle for the TAD mid-woofer.
This would be of course a 4-way system.
Regards,
Claudio.
Dear all,
thanks for your responses and sharing the baffle simulations.
- I intend 400Hz 24dB (acoustically). May be it might become 450 in reality. So far, I have crossed the ATC dome mid at 500 24dB (acoustically) to both the SB75-234 and the PHL B§0-4531 and I cannot understand why it should be best above 600Hz. Contrary - the narrower the mid band is, the more problems arise in the power response and passive crossover design.
- I have thought about the ScanSpeak as well - yet
- Simulations have been done for the woofer based on TSPs for the PHL B30-4021 and the ATC SB75-314SC and for the mid and the DXT using real data. I may upload them, if anyone is interested, yet they use the freeware BoxSim, so you may need some basic German to understand the programme...
- @ mbrennwa: Your project and measurements are very interesting, thank you for sharing. I agree with you conerning the ATC dome and chamfers. But the ATC dome horn/ waveguides leads to increased beaming from 1k on, so the relevance of edge becomes more and more irrelevant. However, I would expect benefits of chamfers to be relevant for the tweeter in the 3k to 6k. I don't know whether you have had a look at Heißmann Acoutics DXT-Mon - w/o chamfers I highly doubt, that the DXT would have integrated so well. There is another DXT 5,5 inch (from hifi-selbstbau.de) - and they get an increased horizontal off-axis response of the DXT at around 3k when placing it in the middle of a roughly 20cm (horizontally) baffle. It needs to be tested.
- I will look at the french forum as well - I still wonder, why there is no comment/ opionion concerning the PHL B30-4021. While it is not a "extra deep-bass" subwoofer, it works well until 32 HZ in a 80l-90l tuned between 30-35 Hz, and has characteristics of "both worlds"....
Best regards,
Leif
thanks for your responses and sharing the baffle simulations.
- I intend 400Hz 24dB (acoustically). May be it might become 450 in reality. So far, I have crossed the ATC dome mid at 500 24dB (acoustically) to both the SB75-234 and the PHL B§0-4531 and I cannot understand why it should be best above 600Hz. Contrary - the narrower the mid band is, the more problems arise in the power response and passive crossover design.
- I have thought about the ScanSpeak as well - yet
- Simulations have been done for the woofer based on TSPs for the PHL B30-4021 and the ATC SB75-314SC and for the mid and the DXT using real data. I may upload them, if anyone is interested, yet they use the freeware BoxSim, so you may need some basic German to understand the programme...
- @ mbrennwa: Your project and measurements are very interesting, thank you for sharing. I agree with you conerning the ATC dome and chamfers. But the ATC dome horn/ waveguides leads to increased beaming from 1k on, so the relevance of edge becomes more and more irrelevant. However, I would expect benefits of chamfers to be relevant for the tweeter in the 3k to 6k. I don't know whether you have had a look at Heißmann Acoutics DXT-Mon - w/o chamfers I highly doubt, that the DXT would have integrated so well. There is another DXT 5,5 inch (from hifi-selbstbau.de) - and they get an increased horizontal off-axis response of the DXT at around 3k when placing it in the middle of a roughly 20cm (horizontally) baffle. It needs to be tested.
- I will look at the french forum as well - I still wonder, why there is no comment/ opionion concerning the PHL B30-4021. While it is not a "extra deep-bass" subwoofer, it works well until 32 HZ in a 80l-90l tuned between 30-35 Hz, and has characteristics of "both worlds"....
Best regards,
Leif
PHL B30 4021
According to Klang+Ton measurements, it is a very good unit for the purpose. Fs=35; Qts=0,37; Vas=55; smooth response all the way to 1 kHz. Found these at LSV Dieter Achenbach.
According to Klang+Ton measurements, it is a very good unit for the purpose. Fs=35; Qts=0,37; Vas=55; smooth response all the way to 1 kHz. Found these at LSV Dieter Achenbach.
I agree with you, Lojzek. Also - as far as I can remember, the B30-4021 was rumored to be used by Klein+Hummel.
http://lsv-achenbach.de/images/lautsprecher/test/kt_test_phl-b30-4021.jpg
This is the link to the test.
Regards,
Leif
http://lsv-achenbach.de/images/lautsprecher/test/kt_test_phl-b30-4021.jpg
This is the link to the test.
Regards,
Leif
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