0.175 = 5 litre, q = 0.781 F3 (for filter purposes) 80 Hz, F6 71 Hz, F10 about 52 Hz. very slight bump. 200 Hz 1/2 wave pipe resonance.
0.0875 = 2.5 litre, Q= 0.965 F3 99 Hz, F6 80 Hz, F10 about 63 Hz. 1 dB bump peaking just below 200 Hz. 400 Hz 1/2 wave pipe resonance.
All above with no damping so will change when required daming is added.
As said earlier, 4” pip is too skinny, you will get early reflection colouration.
Thank you sir for that info!
Crossing the P7's right now @150Hz sounds "pretty good" at close to 90dB about 10ft away in this current 8xP7 per channel setup which are enclosed in 5"x5"x14" MDF boxes.
No comment on the A-10.3m's?
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Unless you need to go lower (which you don’t) there is no need. If you want better the A7.3 is a better choice with higher resolution, better top & bottom, and usually a lower prices. One thing you give up is the tigher spacing possible w the P7 basket.
The need for a bigger pipe is even more critial with the A7, and with the A10 6” pipe would be pushing it, 7” would be better.
dave
The need for a bigger pipe is even more critial with the A7, and with the A10 6” pipe would be pushing it, 7” would be better.
dave
I don't need to go lower Hz, but I was thinking that larger drivers might be more efficient at pushing air for larger SPL's at all frequencies, being a MarkAudio FR driver. Also, smaller enclosure to reach <100Hz (cutoff @150Hz).
I'm arguing for arguments sake, so take it with a grain of salt. I can't afford those Alpair 10.3m @$85US ea yet.
EDIT: The xmax is huge too. Unusual.
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For the past 3 months I've transitioned all the enclosures to a 5" schedule 40 PVC enclosure using 2 endcaps and just about 3" of pipe. Finished painting them, stuffing them loosely with acoustistuff and using cat5e cable for internal wiring. (Credit to me for observing some of Dave's posts 
)
You can read about it here.
A few developments:
1) There's now 12 P7 drivers per side, with room for one more since now my ears do not detect a lack of highs and can loose that AMT tweeter(present in above pics, not below), thus making room for 13 P7's per side.
2) No subs yet, sorely needed... Keeping the 8 SB Acoustics subwoofer drivers. Watch out for what I've got planned! Surely been done before tho...
3) Vinyl plank floors adding all kinds of artifacts I've not heard before when the rectangles were on wall to wall carpet.
4) Towers are wider apart and on casters so they're mobile.
5) I'm researching individual 40-100W class D amps and DSP per driver. Very difficult to find exactly what I want. I've begun posting on the class D section...
In this pic I was leveling them and eyeing the angle of each from a side view.
)You can read about it here.
A few developments:
1) There's now 12 P7 drivers per side, with room for one more since now my ears do not detect a lack of highs and can loose that AMT tweeter(present in above pics, not below), thus making room for 13 P7's per side.
2) No subs yet, sorely needed... Keeping the 8 SB Acoustics subwoofer drivers. Watch out for what I've got planned! Surely been done before tho...
3) Vinyl plank floors adding all kinds of artifacts I've not heard before when the rectangles were on wall to wall carpet.
4) Towers are wider apart and on casters so they're mobile.
5) I'm researching individual 40-100W class D amps and DSP per driver. Very difficult to find exactly what I want. I've begun posting on the class D section...
In this pic I was leveling them and eyeing the angle of each from a side view.
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Looking very “scaena”
Hard to wire 13 up usefully. But separate amps would solve that. You wouldn’t need near that amount of power. But getting DSP along with might push you there.
When you said individual Class D, this is what immediately popped in my head: Sure Electronics AA-AB32231 2x8W at 4 Ohm TPA3110 Class-D Audio Amplifier Board
I have a couple not wired up yet.
dave
Hard to wire 13 up usefully. But separate amps would solve that. You wouldn’t need near that amount of power. But getting DSP along with might push you there.
When you said individual Class D, this is what immediately popped in my head: Sure Electronics AA-AB32231 2x8W at 4 Ohm TPA3110 Class-D Audio Amplifier Board
I have a couple not wired up yet.
dave
Credit Due. I've admitted in the past this DIY is based from Scaena!
Separate amps I've got planned per P7. Each P7 is rated at 20W, but I think when it comes to class D amps, it's best to have 2x to 4x available power to get lesser distortion when the amp is used at lower volume. -deleted ramble-
Time for us FR's to eval class D. Been a long time since the invention of this type amp.... I think it deserves attention, especially when coupled with DSP and Toslink Audio In, AND pass thru
Thanks!
Got a listen last night, definately needed EQ at this point.
Here's the typical listening position: drivers about 9ft apart, with the option to move the couch and left tower 3ft to the left. The listening position centered about 15ft away with ears level from the 5th speaker from the bottom.
More cable management coming.
Got a listen last night, definately needed EQ at this point.
Here's the typical listening position: drivers about 9ft apart, with the option to move the couch and left tower 3ft to the left. The listening position centered about 15ft away with ears level from the 5th speaker from the bottom.
More cable management coming.
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I think I've finally settled on the miniDSP 2in x 4out kit + miniDIGI. The miniDIGI will allow full digital I/O with the miniDSP2x4 programmed with the 31-band GEQ. This plug-in is only $10US! and can do so much more including delay in .02ms increments per channel.
Keeping 12 drivers per side, I would only need 3 of these combo's per side + the class D amp w/optical in. Still have to research that one. So far this part of the project is not overtly expensive, so I can build it up over time. About $350 per side, not including power supplies or USB communications...
So programming these things is going to be the challenge. I might try to make the USB wireless somehow with a wireless hub if this is even possible...
Keeping 12 drivers per side, I would only need 3 of these combo's per side + the class D amp w/optical in. Still have to research that one. So far this part of the project is not overtly expensive, so I can build it up over time. About $350 per side, not including power supplies or USB communications...
So programming these things is going to be the challenge. I might try to make the USB wireless somehow with a wireless hub if this is even possible...
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Well, you have to scratch some things with that setup. The EQ has to be the same for all drivers or, if you have something reflecting nasty on the left/right you cannot move, you'll only need 2 different EQs per side. You don't need an amp for each driver but that's not an issue because of the cheap amplifier boards. But it's really a waste of time and money to give each driver one DSP channel. Even a CBT does not need a dsp for each driver, 3 or 2 drivers per channel is really enough. If you want more, sure, go for it, but you don't get any advantage out of it.
You got a different problem though, your drivers are too far apart. They should be as close as possible together to avoid comb filter effects - because that's something you can't correct with a DSP.
I'd suggest you convert the optical input to coax, that way you can distribute it much easier. Most DSPs don't have a optical input anyway.
You got a different problem though, your drivers are too far apart. They should be as close as possible together to avoid comb filter effects - because that's something you can't correct with a DSP.
I'd suggest you convert the optical input to coax, that way you can distribute it much easier. Most DSPs don't have a optical input anyway.
ICG, I appreciate your input.
But I can say I did choose the 5" PVC endcaps because they are rounded internally and externally. So it was a tradeoff between close drivers or 'the best' diffraction loss. The cylinder shape came 2nd to the sphere shape so I went with it, having already experimented with the rectangular box made of MDF. At that point though, I had only 8 enclosures per side. Now I have 12 per side, so 4 new drivers per side plus all new PVC enclosures. I made the mistake of changing 2 variables at one time, but I wasn't ready/willing/or able to just build 8 more MDF rectangular boxes just for (possibly) nothing..
So yes, I can say when I had these enclosures stacked straight I heard the combing effect. When I started to curve the enclosures, the combing effect started to disappear at about 4 feet away.
But I can say I did choose the 5" PVC endcaps because they are rounded internally and externally. So it was a tradeoff between close drivers or 'the best' diffraction loss. The cylinder shape came 2nd to the sphere shape so I went with it, having already experimented with the rectangular box made of MDF. At that point though, I had only 8 enclosures per side. Now I have 12 per side, so 4 new drivers per side plus all new PVC enclosures. I made the mistake of changing 2 variables at one time, but I wasn't ready/willing/or able to just build 8 more MDF rectangular boxes just for (possibly) nothing..
So yes, I can say when I had these enclosures stacked straight I heard the combing effect. When I started to curve the enclosures, the combing effect started to disappear at about 4 feet away.
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The small PVC enclosures need EQ. They're barely reaching 150Hz. Also, I've also wanted individual powered drivers. I've chosen 100W mono class D amps, so the distortion should be very low with the P7 watt max at 20W.
The miniDSP can also do alot. Only 1 is needed per 4 drivers. Each output can be individually programmed.
Gentlemen, I apologize. I had the drivers wired incorrectly. I originally thought I had a hidden short somewhere when the amp would thermal shutdown at moderate to loud volume levels. Drawing the wiring connections made me finally realize they were essentially all wired in parallel. Idiot
Now that each side is finally wired correctly, I no longer need EQ and they sound great again! 4 groups of 3 (8 ohm) speakers in parallel wired in series for about 12 ohms.
(...these vagabond shoes...) Frank Sinatra sounds real good now. Now to get the subs up to snuff. These will need individual EQ/Amp
Now that each side is finally wired correctly, I no longer need EQ and they sound great again! 4 groups of 3 (8 ohm) speakers in parallel wired in series for about 12 ohms.
(...these vagabond shoes...) Frank Sinatra sounds real good now. Now to get the subs up to snuff. These will need individual EQ/Amp
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