No... we're talking about volume displacement. The resonant frequency of the driver has nothing to do with that. Volume displacement is Sd multiplied by Xmax, and dictates the amount of air a transducer can displace, and from this you can determine exactly what output is achievable at what frequency.
Look up "volume displacement vs. SPL" to find the charts. Fs of the driver does not factor into this.
As for the rest of the low frequency/subwoofer talk, I would agree pretty strongly with fluid in stating that you're looking to solve a problem that doesn't exist, and you will almost certainly cause more harm than good. The only exception I could think of would be for home theater use where a dedicated LF channel may still be beneficial.
My single favorite trait of the line array is the impeccable low frequency integration. I've had dual B&C 21" subwoofers in both vented and sealed enclosures, dual 10" Peerless driver setups, a pair of 18" Goldwood drivers in H-frames, quad CSS 10" woofer setups, and even a setup with a pair of those crazy 12" backwards Volt drivers. Absolutely none of the above could produce bass as effortlessly and as perfectly integrated as the arrays. The B&C drivers were capable of more output, but certainly not more quality. If all you want is output, then there are very cheap solutions out there which can get you just that. I don't think that's the purpose of this thread.
After the massive success of the arrays I decided that maybe I could do one better with a pair of RD-75 drivers and the right subwoofer setup. The RD-75 drivers do give the arrays a run for their money above about 800Hz, but getting subwoofers to integrate properly was impossible, and I tried pretty much everything. The lowest you can cross the RD-75s is at about 175Hz, and you need a 4th order, and still need to limit output. Crossing any subwoofer that high, especially when it's crossing to a line array, is a very bad idea. At the end of the whole thing, I sold the RD-75s, kept the TC9 arrays, and the subs are current sitting unused in my garage
As a heads up, I ran the indoor measurements, but still need to compile and post the data. I might get the outdoor ones done this weekend if time permits.
Regards,
Owen
Thanks for posting Owen, I remember you posting about having trouble getting subwoofers to integrate but I couldn't remember in which thread it was to quote.
Modulation distortion is more likely with a full range driver compared to a multiway and that doesn't really show in a harmonic distortion test from sine sweeps.
What seems to be forgotten sometimes is that all designs have compromises and you have to pick the ones you can live with. No full range array could hope to compete with separate subs in output but they do excel in other areas.
I tend to think of this like sports teams. The most successful team is the one that play's the best together, not the one that has the best individual players.
Looking forward to seeing the measurements when you get the time to post them
Modulation distortion is more likely with a full range driver compared to a multiway and that doesn't really show in a harmonic distortion test from sine sweeps.
What seems to be forgotten sometimes is that all designs have compromises and you have to pick the ones you can live with. No full range array could hope to compete with separate subs in output but they do excel in other areas.
I tend to think of this like sports teams. The most successful team is the one that play's the best together, not the one that has the best individual players.
Looking forward to seeing the measurements when you get the time to post them
Great thanks guys the many good inputs found this thread, no doubt demo me and xrk971 had visiting wesayso that we at distance listened a world class acoustic sound stage unite system/speaker/room closer to a silk clean headphone like sound than we probably ever heard before except near field. Latest opc post tilt my own thinking about other than electric domain in the acoustic domain its really hard to perfect unite parallel subs or super tweeters so that if we leave HT out of picture then for reproducing music nothing seems to beat these line arrays and their snappy coherent phase response from the very wide pass band that is within reach when inside a room, can see for myself arrow points more and more to building a pair for music use because even Synergy will get the problems real world unite system/speaker/room.
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Methinks torgeirs has always built/used multi-way speakers and has a difficult time believing the low end you guys get from your arrays. I'm very seriously considering building the Parts Express Epique CBT24K Line Array kit. My Acoustat Model 3's just don't fit my dual-purpose music/HT room with my 134" projection screen. After I upgrades the caps, resistors and wire in the interfaces, I'll put them up for sale - or maybe sell them as-is, since they have great SQ and don't really need my fanatic upgrades. The PE Epiques sound front is very interesting and Don Keele's YouTube videos explaining it are quite interesting. I would integrate OB servo subs crossed at ~100Hz. Rythmic plate amp and either his or GR Research drivers in a W frame.
BTW, thanks to Wesayso, Fluid and others' sharing the details of their builds and testing and knowledge. It's been a learning experience that I appreciate!
BTW, thanks to Wesayso, Fluid and others' sharing the details of their builds and testing and knowledge. It's been a learning experience that I appreciate!
I don't understand that kit, in particular the driver they are using. It has lower efficiency, reduced xmax at 1.9mm, the frequency response is not very smooth and has very little low frequency output. With only 24 of those it would have to be crossed to subs to get any real bass at all other than at quite low spl's.
A floor to ceiling straight line of 35 to 40 of them would work better in my mind. The CBT concept is interesting but it takes such a lot of floor space so it doesn't appeal to me.
Did you read OPC's thoughts on subwoofers above? That was one of the reasons I wanted to be able to run full range EQ. Wesayso's plans with his subs aren't for a straight crossover either. RA7 crosses to subs but his smaller cabinet volume from the corner placement would make it a little harder to EQ all the way down and his setup looks to be for home theatre too where the subs make much more sense.
Glad you have found it useful
I couldn't help myself Owen's comment about volume displacement got me thinking that I could compare the array to my LX521 speaker that has two 10" Seas drivers with 14mm x-max in an open baffle. Here is the linkwitz spl max spreadsheet, green is the LX521 and blue the array. They are the same at 50Hz and below 50Hz the array has more output. The red line is the two 10" woofers in a sealed cabinet for comparison.
In my current room the LX521 can produce more than enough low bass for my taste even on tracks that have significant content below 30Hz which really pumps the woofers. It is the sound of the mids and high frequencies that has me turning the volume down.
The linkwitz values are a bit lower than some other calculators. The 94dB at 30 Hz that Torgeirs quoted, is the exact same figure that Bassboxx Pro gives for 25 of the TC9 drivers at x-max in my cabinet.
Click on the attached image at the bottom for full size image.
This compares well to the Small chart for VD vs SPL. A single array has a VD of 235cm3 and the 200cm3 line is at 96dB which is a peak figure and would be 93dB for RMS.
Owen's comment about volume displacement got me thinking that I could compare the array to my LX521 speaker that has two 10" Seas drivers with 14mm x-max in an open baffle. Here is the linkwitz spl max spreadsheet, green is the LX521 and blue the array. They are the same at 50Hz and below 50Hz the array has more output. The red line is the two 10" woofers in a sealed cabinet for comparison.In my current room the LX521 can produce more than enough low bass for my taste even on tracks that have significant content below 30Hz which really pumps the woofers. It is the sound of the mids and high frequencies that has me turning the volume down.
The linkwitz values are a bit lower than some other calculators. The 94dB at 30 Hz that Torgeirs quoted, is the exact same figure that Bassboxx Pro gives for 25 of the TC9 drivers at x-max in my cabinet.
Click on the attached image at the bottom for full size image.
This compares well to the Small chart for VD vs SPL. A single array has a VD of 235cm3 and the 200cm3 line is at 96dB which is a peak figure and would be 93dB for RMS.
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Don't have to look up volume displacement,OPC
16 inch at 3 mm xmax will output the same as an 8 inch 12mm xmax.
So if that is enough for needed SPL, then all OK.
Then there are the distorion at HF because of bass driving the membrane out of linear region. So xmax of 12 mm is not feasible for undistorted HF. I would go down 20 dB to 1,2 mm.
Then it compares to a sub with 4 inch and 5 mm xmax.
So my suprise is that it can be suficient.
The Fs explains the extreeme midbass SPLs possible
16 inch at 3 mm xmax will output the same as an 8 inch 12mm xmax.
So if that is enough for needed SPL, then all OK.
Then there are the distorion at HF because of bass driving the membrane out of linear region. So xmax of 12 mm is not feasible for undistorted HF. I would go down 20 dB to 1,2 mm.
Then it compares to a sub with 4 inch and 5 mm xmax.
So my suprise is that it can be suficient.
The Fs explains the extreeme midbass SPLs possible
Show me the songs that blast full power at 30 Hz... I've shown one I have encountered.
But they are pretty rare in my collection.
The Fs doesn't explain midbass, the Vd does. And we only loose 3 dB for each doubling of distance there. Due to using processing we have a total lack of regard for Fs.
Not quite, but close:
Yup, and now add the room gain (BYRRT's chart seems about right) due to the arrays being close enough to the wall to profit from that.
We've had 3 people in here that have had arrays for years, one extra source that has listened to one for more than just a couple of hours and one that's currently building a set .
Only one nay sayer... I think I'm done with this part of the discussion. I get the feeling the needle is stuck. We don't move ahead. We never claimed the impossible here, just reality. No laws were broken.
Even though I have plans to play with subs myself, it isn't SPL related. They won't use standard crossovers and will be used to even out my left and right balance so I don't have to do it with the arrays. It will be a FIR controlled multi sub solution with the arrays acting as 2 of those subs. It will probably give me enough headroom for HT as a bonus, if it works out at all. That part remains uncertain. Again, this addition is curiosity driven, not out of necessity. It will be triple the Sd area I have now.
A single Scan Speak 30W type of driver (I'll be using 2):
466 x 12.5 = 5825 (volume displacement)
One array of TC9's (I am using 2):
36 x 25 x 2.55 = 2295 (volume displacement)
The question is how it will work in a room. The arrays have been very forgiving in that department due to their ability to average (out reflections) based on all the different positions of the drivers.
But they are pretty rare in my collection.
The Fs doesn't explain midbass, the Vd does. And we only loose 3 dB for each doubling of distance there. Due to using processing we have a total lack of regard for Fs.
Not quite, but close:
This compares well to the Small chart for VD vs SPL. A single array has a VD of 235cm3 and the 200cm3 line is at 96dB which is a peak figure and would be 93dB for RMS.
Yup, and now add the room gain (BYRRT's chart seems about right) due to the arrays being close enough to the wall to profit from that.
We've had 3 people in here that have had arrays for years, one extra source that has listened to one for more than just a couple of hours and one that's currently building a set .
Only one nay sayer... I think I'm done with this part of the discussion. I get the feeling the needle is stuck. We don't move ahead. We never claimed the impossible here, just reality. No laws were broken.
Even though I have plans to play with subs myself, it isn't SPL related. They won't use standard crossovers and will be used to even out my left and right balance so I don't have to do it with the arrays. It will be a FIR controlled multi sub solution with the arrays acting as 2 of those subs. It will probably give me enough headroom for HT as a bonus, if it works out at all. That part remains uncertain. Again, this addition is curiosity driven, not out of necessity. It will be triple the Sd area I have now.
A single Scan Speak 30W type of driver (I'll be using 2):
466 x 12.5 = 5825 (volume displacement)
One array of TC9's (I am using 2):
36 x 25 x 2.55 = 2295 (volume displacement)
The question is how it will work in a room. The arrays have been very forgiving in that department due to their ability to average (out reflections) based on all the different positions of the drivers.
It was interesting for a while, and you guys shared some cool information, thank you, but now, this is getting boring a little...
You know guys, there's some people that still think the earth is flat... you just can't win them all... some will believe what they want to believe. Dogma is a hard thing to let go.
You know guys, there's some people that still think the earth is flat... you just can't win them all... some will believe what they want to believe. Dogma is a hard thing to let go.
Fluid, I plan to use OB servo subs - they're quick enough to keep up integrated with OB's and 'stats. I plan to do a couple of them and cross at ~90Hz. In the Epique kit description: "The ND64-16 is truly a full-range driver and capable of over 6 mm of peak-to-peak excursion" Xmax is 1.9mm. The Peerless is 1.6mm. But the ND64 Sd is of course less than half the Peerless: 15.6 cm^2 versus 36.3 cm^2. The complete system curve looks very good. Maybe add DSP to tweak the top end.
I agree it's time to leave the low end response issue lying on the floor and move on to more interesting testing/discovering/tweaking.
I agree it's time to leave the low end response issue lying on the floor and move on to more interesting testing/discovering/tweaking.
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Let's not bring up the speed of sub woofers as that is another rabbit hole many threads have been down already
There is a fair bit of marketing speak in their description which is to be expected from a commercial document.
"capable of over 6 mm of peak-to-peak excursion" means x-mech is close to 3mm, the x-max figure of 1.9mm from the driver data is more useful to me.
If by the Peerless you mean the TC9 then it has 2.6mm of x-max on the latest datasheet not 1.6mm.
To compare VD
Epique24 15.6 x 24 x 0.19cm = 71.1cm3
TC9 Line Array 36.3 x 25 x 0.26cm = 235.95cm3
That is why I am not so keen on it as it doesn't have the capability to be EQ'd at the low end in the same way.
That was one of the main drawcards to me from OPC and Wesayso's descriptions the quality of the bass .
If you plan to cross to subs regardless then all of the above won't matter to you. The finished version at $300 extra looks good value compared to the kit as there is a lot of work to build them up
Here is my array outdoors with and without basic EQ on a graph with 1/12 Oct smoothing that has a similar scale for comparison.
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Of course Fs matters. Below Fs, you need higher and higher amounts of EQ and power. Remember that this is a driver with an Fs of 125 Hz. While the idea of single driver (albeit 50 of them) operating from 20 Hz to 20 kHz sounds romantic, there is no real downside to using multiple subs and evening out the room response. Once properly integrated I bet you cannot tell the difference between the two arrangements.
I like the idea of two speakers that take up very little space and can play full range enough for music, I don't think that is "romantic".
To me the down side of multiple subs is that I then have to have multiple extra speakers and amps in the room Their position to make the best sound may not fit very well with using the room for family purposes either.
That is practicality and has nothing to do with their ability to integrate or provide a better response, I just don't want them.
Your solution of squeezing them into the corners and using multiple subs looks to work very well but I didn't want to go that way.
Maybe you were lucky, or maybe you did a really good job of integrating them. OPC is not the only person to post that they have had trouble getting the subs to work the way they want them to.
I know it would be less ideal with your small cabinet, but did you ever EQ it to 20 or 30 Hz and listen to it that way?
To me the down side of multiple subs is that I then have to have multiple extra speakers and amps in the room
Their position to make the best sound may not fit very well with using the room for family purposes either. That is practicality and has nothing to do with their ability to integrate or provide a better response, I just don't want them.
Your solution of squeezing them into the corners and using multiple subs looks to work very well but I didn't want to go that way.
Maybe you were lucky, or maybe you did a really good job of integrating them. OPC is not the only person to post that they have had trouble getting the subs to work the way they want them to.
I know it would be less ideal with your small cabinet, but did you ever EQ it to 20 or 30 Hz and listen to it that way?
The disregard for Fs I mention needs some explaining I see. As long as there is room for EQ, both in output of the drivers as well as the headroom in the rest of the chain, the exact point of that Fs does not matter. Without EQ these things will sound like .....
As for the other point, we know we disagree on a few things there, I'd simply have to try and see for myself, like with the wiring debate a few pages ago.
I cannot make up my mind based on guessing. In other words: I won't bet on it.
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Let's not bring up the speed of sub woofers as that is another rabbit hole many threads have been down already
He ( Hank) is right, a woofer in OB works with velocity
Becauseee....
( it has to do with Z of air and the reactive part and the resistive part, plus the excursion
)
Yes; Power Output (SPL) = Z x vIt's a difference beeing a neysayer and be supprised
Just to clarefy Fs:
free air reference efficency is dependent on fs^3
In most cases there are a link between this value, max SPL and the max SPL possible at frequencies below fs.
Z- acoustic impedance ; v -velocity of the membrane
It applies to speakers and headphones but not the closed ( tightly ) ones or the in-ear types ( it's a pressure mode of operation ).
As frequency goes down, the movement of the cone is slow ( low freq - less periodic movement ) so the equation is like the Ohm's law.
resistive and reactive part determine how much of the cone movement is translated into useful output. High Z makes "good coupling" so the "trasduction" is optimal.