250 Hz,wow, that's extremely high in my eyes. 130 probably sounds a lot better, doesn't it 
. Still too high for me though, but that might be due to my subs (BF Titan 48, Art's Keystone, diy tapped horn/drumrizer sub). I find them all way too 'boxy' if I let them play that high. Plus you can locate them much more easily (mostly I do 2+1 setups). I prefer crossing them 80 to 100 Hz, like many others...
. Still too high for me though, but that might be due to my subs (BF Titan 48, Art's Keystone, diy tapped horn/drumrizer sub). I find them all way too 'boxy' if I let them play that high. Plus you can locate them much more easily (mostly I do 2+1 setups). I prefer crossing them 80 to 100 Hz, like many others...I did a quick phase equalization with rePhase, on top of the IIR filters in the miniDSP, and got pretty reasonable square wave response both on and off axis (300 Hz, 3 kHz, 1 kHz, and 100 Hz). First set of plots is IIR, second set is FIR on axis, and third set is FIR 30 degrees off axis. I didn't do any additional amplitude equalization. I am running the FIR phase filter on my laptop with Equalizer APO.
The interesting thing is that I can tell very little difference, with and without, in listening tests. There is a difference with a preference for the linear phase, but it is subtle.
The interesting thing is that I can tell very little difference, with and without, in listening tests. There is a difference with a preference for the linear phase, but it is subtle.
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I had some time alone in the house today and got a chance to do some more serious listening at higher volume. I can definitely and reliably tell when the phase compensation is on and I definitely prefer it. It makes the midrange somehow sound less hashy and and a bit more silky. It creates a sense of "blackness" between sounds that is missing without the FIR. I am not trying to be provocative with the adjectives, but I don't know how to describe it better. On voices, it sounds like the voice is coming from the throat of a person rather than from the throat of a horn. I can't explain it, but I like it, and now I have to figure out if I can afford to add FIR processing to my PA.
Marc
Matches my experience with linear phase. Can be hit or miss with recorded material but overall it's a definite improvement. Especially noticable during longer listening sessions. Don't really experience ear fatigue anymore. This is not to say it's more important than other aspects of speaker design like frequency response. More like the final touch to a good system.
There are ways to get linear phase with IIR filters but it might not work in this particular case because of bandwidth requirements. Take a look at the "harsch crossover" thread if interested.
There are ways to get linear phase with IIR filters but it might not work in this particular case because of bandwidth requirements. Take a look at the "harsch crossover" thread if interested.
I have looked at and played with Harsch crossovers in my living room, and it did make a little bit of difference. I feel like this implementation makes more of a difference than I remember for the Harsch with different speakers. Also, I don't have enough bandwidth available at the bottom of the midrange to do a 12 dB/oct crossover. And, for power handling, I prefer steeper crossovers for PA.
Having said that, as nice as it sounds with the FIR, I think it would still be quite acceptable even with simple LR24 IIR filters. I may see if I can implement the FIR correction in some flavor of Rasberry Pi. I trust a small, simple computer to keep running and not to try something stupid like updating the operating system in the middle of a song as a Windows machine might. So maybe Rasberry Pi into my Driverack PA2.
I would love to get a Lake processor, but I am only doing this for fun right now. If I start getting some paid gigs, I may sink the money back into equipment.
Marc
Having said that, as nice as it sounds with the FIR, I think it would still be quite acceptable even with simple LR24 IIR filters. I may see if I can implement the FIR correction in some flavor of Rasberry Pi. I trust a small, simple computer to keep running and not to try something stupid like updating the operating system in the middle of a song as a Windows machine might. So maybe Rasberry Pi into my Driverack PA2.
I would love to get a Lake processor, but I am only doing this for fun right now. If I start getting some paid gigs, I may sink the money back into equipment.
Marc
I still haven't built a second set of subs and a second top, and I still need to round corners, add grilles, and paint them, but I did get my system out this weekend for a little background music near the dock and the food tent at a regatta our rowing club runs annually.
Rain was in the forecast so, for safety, I didn't want to bring my generator and big amps. I used a small 2.1 class D amp and a miniDSP running from two 7 Ah SLA batteries, and it was only drawing about 0.1 amps. I didn't check with a meter, but my guess is I was running about 75 dBA of music at 10m, which was plenty. At the end of the day, I cranked it up the rest of the way, and probably had another 10 dB in reserve.
In the future, I will probably get some tall tripods, and configure the subs in an endfire array, but the stacked subs got my HF horn up to about 100 inches off the ground and that worked very well.
I am looking forward to finishing everything by fall and trying it out at war volume.
Marc
Rain was in the forecast so, for safety, I didn't want to bring my generator and big amps. I used a small 2.1 class D amp and a miniDSP running from two 7 Ah SLA batteries, and it was only drawing about 0.1 amps. I didn't check with a meter, but my guess is I was running about 75 dBA of music at 10m, which was plenty. At the end of the day, I cranked it up the rest of the way, and probably had another 10 dB in reserve.
In the future, I will probably get some tall tripods, and configure the subs in an endfire array, but the stacked subs got my HF horn up to about 100 inches off the ground and that worked very well.
I am looking forward to finishing everything by fall and trying it out at war volume.
Marc
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I made a bit more progress. We had our end of summer picnic at work, so I worked like crazy to make the deadline last Thursday night for the next day.
I finished four more subs, built two proper tops and painted everything (only 1 coat--more later). I spent 5 hours making up cables and wiring Speakon connectors. I had just enough time to set everything up in the back yard for a quick checkout, just setting sub levels, as it got dark, then loaded into my SUV.
Last Friday, we had our picnic, and the sound was good. I ran the system on a Peavey VSX48e and three NU4-6000 amplifiers. We really didn't need that much power. I had a Honda EU2000i generator, and we were using 270 watts with no signal, and 280W to make 85 dBA slow at 10m with music. One day I will get a chance to find out what the system can really do. I can't wait! I haven't unloaded the truck yet, since I still want to get it out in the back yard again to check the DSP tuning.
They still need grills and another coat of paint, and I have to work on my truck pack. I had to put the amp rack in the front seat of the truck. I also need to get some tripod stands so I don't have to do the makeshift stack on the old pallets.
Marc
I finished four more subs, built two proper tops and painted everything (only 1 coat--more later). I spent 5 hours making up cables and wiring Speakon connectors. I had just enough time to set everything up in the back yard for a quick checkout, just setting sub levels, as it got dark, then loaded into my SUV.
Last Friday, we had our picnic, and the sound was good. I ran the system on a Peavey VSX48e and three NU4-6000 amplifiers. We really didn't need that much power. I had a Honda EU2000i generator, and we were using 270 watts with no signal, and 280W to make 85 dBA slow at 10m with music. One day I will get a chance to find out what the system can really do. I can't wait! I haven't unloaded the truck yet, since I still want to get it out in the back yard again to check the DSP tuning.
They still need grills and another coat of paint, and I have to work on my truck pack. I had to put the amp rack in the front seat of the truck. I also need to get some tripod stands so I don't have to do the makeshift stack on the old pallets.
Marc
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Yesterday was perfect weather, so I spent the afternoon in the back yard getting some measurements and tuning. Later, I will post some graphs and polars, but for now, I want to check my understanding.
I have a 94 dB acoustic microphone calibrator, so I trust my SPLs are within 1 dB of my measurements. After equalizing my mid/high top and my 4 stacked subs, I wanted to check the efficiency.
I used brick wall band limited Periodic Pink Noise and measured RMS voltage to each band. I measured SPL at the ground plane 10 meters away.
The measurements:
1) 99.5 dBC at 10 m with 8.7 Vrms 35 Hz to 140 Hz pink noise to four 8 ohm subs in parallel. +15.8 dBWatt
2) 96 dBC at 10 m with 5.6 Vrms 140 Hz to 1000 Hz pink noise to on 8 ohm midbass. +5.9 dBWatt
3) 96.5 dBC at 10 m with 2.7 Vrms 1000 Hz to 15000 Hz pink noise to one 8 ohm compression horn. -0.4 dBWatt
If I am doing this right, I think I need to subtract 6 dB from the measurements to account for the microphone being against a 2 pi boundary, add 20 dB for the 10 meters, and subtract the dBWatt to bring it to 1W. This should give me the 2 pi efficiency for the subs since they are close enough to be coupled to their reflected images.
The results are:
1) 98 dB 1W 1m for the four subs, 92 dB 1W 1m for a single sub
2) 104 dB 1W 1m for the mid
3) 110 dB 1W 1m for the horn.
These numbers all make sense to me given the drivers I am using. I may need to add about 1 dB to the sub efficiency, since C-weighting is -3dB at 31.5 Hz. My only question is why I see lots of references to subtracting 6 dB for ground plane measurements, and none for subtracting 12 dB to convert to 4 pi space for the speakers.
I have a 94 dB acoustic microphone calibrator, so I trust my SPLs are within 1 dB of my measurements. After equalizing my mid/high top and my 4 stacked subs, I wanted to check the efficiency.
I used brick wall band limited Periodic Pink Noise and measured RMS voltage to each band. I measured SPL at the ground plane 10 meters away.
The measurements:
1) 99.5 dBC at 10 m with 8.7 Vrms 35 Hz to 140 Hz pink noise to four 8 ohm subs in parallel. +15.8 dBWatt
2) 96 dBC at 10 m with 5.6 Vrms 140 Hz to 1000 Hz pink noise to on 8 ohm midbass. +5.9 dBWatt
3) 96.5 dBC at 10 m with 2.7 Vrms 1000 Hz to 15000 Hz pink noise to one 8 ohm compression horn. -0.4 dBWatt
If I am doing this right, I think I need to subtract 6 dB from the measurements to account for the microphone being against a 2 pi boundary, add 20 dB for the 10 meters, and subtract the dBWatt to bring it to 1W. This should give me the 2 pi efficiency for the subs since they are close enough to be coupled to their reflected images.
The results are:
1) 98 dB 1W 1m for the four subs, 92 dB 1W 1m for a single sub
2) 104 dB 1W 1m for the mid
3) 110 dB 1W 1m for the horn.
These numbers all make sense to me given the drivers I am using. I may need to add about 1 dB to the sub efficiency, since C-weighting is -3dB at 31.5 Hz. My only question is why I see lots of references to subtracting 6 dB for ground plane measurements, and none for subtracting 12 dB to convert to 4 pi space for the speakers.
I can carry two at a time, one in each hand, from the handle/brace in the port.
Small boxes fit better in tight spaces.
So the real test: Does it all fit in the car??
Yes, not quite the way I was thinking it would, but it works well enough. Eight subs, two tops, rack and cables. I suspect I can even fit my generator in there without having to use up the front seat.
140dB PA that fits in an SUV.
Marc
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I am wondering the same thing myself. I have not had an opportunity to let it loose yet except in my basement with earplugs and earmuffs on (where it sounds clean and undistorted up to clipping). I may get a chance over the holidays at a dance/DJ event, but I am not quite ready for live sound yet. I need to build some stage monitors and buy some mic stands before I go looking for a first gig.
Ideally, I would like to find someone locally with a JBL SRX or Yamaha DSR rig who is willing to play around doing a shootout for a couple of hours in a warehouse in Trenton, NJ, but I know that is not very likely.
Marc
Ideally, I would like to find someone locally with a JBL SRX or Yamaha DSR rig who is willing to play around doing a shootout for a couple of hours in a warehouse in Trenton, NJ, but I know that is not very likely.
Marc
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