That's what I thought. I was wrong. With two drivers not only the midbass is way better, but also all speaker sound much better. More precise, I think.
Weltersys, what would you say is the maximum continuous SPL of the SyntripP at 1m if high passed at 90hz 24dB/oct? (assuming a high quality 3" VC compression driver is used).
I'm looking at building a pair of these for outdoor DJ events for up to 1000 people and would probably need about 100dBA slow at 100 feet/30m out. Subs would be 2 or 3 TH-18's per side.
Also if one were to use an expensive 4" VC compression driver, allowing a lower xo of about 700-800hz would this be a good idea for high continuous output (as the woofers could then be low passed lower)? I'm not so fussed with having a sparkly top-end as there is a lot of HF attenuation with distance anyway.
I'm looking at building a pair of these for outdoor DJ events for up to 1000 people and would probably need about 100dBA slow at 100 feet/30m out. Subs would be 2 or 3 TH-18's per side.
Also if one were to use an expensive 4" VC compression driver, allowing a lower xo of about 700-800hz would this be a good idea for high continuous output (as the woofers could then be low passed lower)? I'm not so fussed with having a sparkly top-end as there is a lot of HF attenuation with distance anyway.
1) Around 120 dB in the low end of the 10" pass-band.
2) With a pair of SynTripP in the center at 104 feet/32 meter you'd be looking at around 96 dB. For 4 to 6 TH 18" subs, go with something like Peter Morris' DIY
New DIY Mid High | Sound Forums
or a small format line array to keep up.
3) That would not make much difference at all, since the low end (90-200 Hz) will be the limiting factor.
4) EQ and headroom can overcome that, but hot and dry sucks the highs like crazy. In New Mexico, I was using 10) 3" diaphragm HF to 2) 1x18" Keystone TH.
2) With a pair of SynTripP in the center at 104 feet/32 meter you'd be looking at around 96 dB. For 4 to 6 TH 18" subs, go with something like Peter Morris' DIY
New DIY Mid High | Sound Forums
or a small format line array to keep up.
3) That would not make much difference at all, since the low end (90-200 Hz) will be the limiting factor.
4) EQ and headroom can overcome that, but hot and dry sucks the highs like crazy. In New Mexico, I was using 10) 3" diaphragm HF to 2) 1x18" Keystone TH.
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Thanks weltersys! Actually now looking back at the sims, one can clearly see that the low end is the weakest link. The dream would be to build a synergy horn like yours but with almost similar output capability to Peter Morris' DIY - I want to crush all these muddy sounding small format line arrays!
As your SynTripP is so lightweight, I would be prepared to modify it and make it bigger and heavier (up to 30kg would be fine for me).
1) What would be the easiest way to modify it for higher bass output? I see there was talk in the original design discussion of adding a 3rd 10" woofer ontop. Perhaps less than 130dB for the low end would be fine considering the haystacked LF response of the TH-18's would contribute to some of the lower midbass output.
2) What about also increasing the size of the horn? Space is not an issue for me.
As your SynTripP is so lightweight, I would be prepared to modify it and make it bigger and heavier (up to 30kg would be fine for me).
1) What would be the easiest way to modify it for higher bass output? I see there was talk in the original design discussion of adding a 3rd 10" woofer ontop. Perhaps less than 130dB for the low end would be fine considering the haystacked LF response of the TH-18's would contribute to some of the lower midbass output.
2) What about also increasing the size of the horn? Space is not an issue for me.
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Fenis,
1) If there was an easy way to "modify" the SynTripP for higher bass output, I would have done it ;^).
Three TH-18 can achieve more than 140 dB in the crossover region. To properly keep up with them in a multiple entry horn would require something on the order of DSL's SH-96, which uses 4x15", 6x4", and a 3" diaphragm 1.4" exit driver.
That would be a completely different design, not a modification.
You could "scale up" and go with a 2x15" and a 4" diaphragm HF and get within around 6 dB of the SH-96, but it would still be a completely different design, and probably would still exceed 30kg unless using exotic materials.
2) A larger 90 x 40 conical horn won't increase LF level much at all above 90 Hz.
Cheers,
Art
1) If there was an easy way to "modify" the SynTripP for higher bass output, I would have done it ;^).
Three TH-18 can achieve more than 140 dB in the crossover region. To properly keep up with them in a multiple entry horn would require something on the order of DSL's SH-96, which uses 4x15", 6x4", and a 3" diaphragm 1.4" exit driver.
That would be a completely different design, not a modification.
You could "scale up" and go with a 2x15" and a 4" diaphragm HF and get within around 6 dB of the SH-96, but it would still be a completely different design, and probably would still exceed 30kg unless using exotic materials.
2) A larger 90 x 40 conical horn won't increase LF level much at all above 90 Hz.
Cheers,
Art
I was thinking about one speaker and have some tests done. While two B&C 10CL51 are way better then one, I have some interesting results with JBL 2123 in 10l modified "SynTripp".
From 200hz up there are obvious qualities that makes this driver something special. It lost the precision, wide range, stage and simplicity of two B&C 10CL51, but it has that 'air' associated with uncompromising horn system. May be because it has risen response in 700-900hz, I don't know, but the magic is there. I'm interested what Art think about that?
Sounds like I may need to go with Peter Moris' dual horn loaded 12's with BMS Coaxial CD. Alternatively I could build a midbass horn to go with a sealed version of your SynTripP to cover 80-300hz. That would be a killer high SPL system but would mean lugging another pair of boxes. Also a 300hz xo could be problematic if the SynTripP needs to be raised high, separately from the midbass horn and subwoofer.
Noob question: The bass reflex re-injection ports are obviously a great way to get more SPL in the low midbass. Is the output from these ports less than 180degs out of phase due to the time delay of the sound waves travelling from the inner ports and through the horn?
The Danley SH46 has a similar design (minus it being 3-way) with the bass re-injection ports and according to their phase trace it still looks really good from 70-100hz:
A normal bass reflex speaker has a lot of group delay which I don't like the sound of.
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Intuitively, it would seem that putting a big hunk of plywood in front of a loudspeaker and forcing all the output through a 3/4" hole would screw up the response in a huge way.
But all it does, for the most part, is act as a low pass filter.
An electrical low pass filter, like an inductor, won't reduce harmonic distortion. For instance, if your midrange is playing 1000Hz and generating 2nd harmonics at 2000hz and 3rd harmonics at 3000Hz, an inductor won't reduce those. This is a real issue, because the harmonic distortion from your midrange can 'pollute' the sound being played by your tweeter.
An acoustic low pass filter, like in a horn, DOES reduce harmonic distortion. The low pass filter is created by the volume of air between the cone and the wall of the loudspeaker, and that reduces ALL output: the fundamental and the distortion.
As to whether it reduces output across the board, no it does not. It's an acoustic low pass filter, nothing more.
Another advantage of the setup is that it makes the speaker 'appear' to be much smaller. For instance, the 5" midranges in an SH50 are 'funneled' through two ports that measure 3/4" in diameter. Acoustically, the midranges behave as if they're two point sources measuring 3/4" in diameter. This improves the polar response.
Very good pointers there to pros and cons, thanks.
Good old WinISD 0.44 can simulate 4th order band pass and looks like its a balance thing, what i mean is when for port we begin to ask for higher extension we make front chamber smaller and tuning frq higher but front verse rear chamber and tuning frq verse port band width all have consequences. As can be seen below using same driver for all examples yellow is the reference SPL using a simple sealed BW2 box, port band width asked of the two dark blue band passes can happen without any SPL punishment, but bablance of front verse rear chamber plus tuning frq asking for port band width in the light blue example have consequence on final SPL.
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Sergy,
The JBL 2123 is a very different driver than the B&C 10CL51, I'd expect their response to be different as well.
Can't comment past that on a magic show I have not seen ;^).
Art
Fenis,
1)The SynTripP LF has an average of about 120 degrees of phase shift over the 10" pass band from 81 to 800 Hz.
2) The Danley SH46 12" has around 135 degrees of phase shift over the pass band from 70-250 Hz.
3)I guess you'd dislike the sound of these speaker's group delay about 1/3 less ;^) .
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One thing that might not be immediately obvious, is that you can raise the overall output of the loudspeaker by tinkering with the volume of air in the back chamber of the midrange on the horn.
See how a sealed box 'peaks' as you make the back chamber too small? You can use this to your advantage on a horn. Basically the small backchamber raises the output on the LOW end, and the horn raises the output on the HIGH end.
If you juggle this carefully you can get overall response that's flat, even though the Q of the sealed chamber in the horn is very high. IIRC, the Q on the Misco midranges used in the original Unity horn is something like 1.5. (0.7 is generally regarded as "ideal.")
Long story short, if you're willing to sacrifice some low end, you can have a horn speaker with overall output that's quite a bit louder than the same driver in a sealed box, even if the horn isn't sufficiently large.
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Oh geez I was reading the wrong axis scale on the SH46 graph, told you I was a noob!
So not quite 180degs like a conventional bass reflex. Does the 120 deg shift still make it more challenging to get a good phase coherent crossover to subs? I am slightly OCD about this as I like a good, clean punch which is coherent with the high frequency component of the kick.
The less phase shift between pass bands of components, the less challenging it is to achieve a smooth phase (and frequency) response between them.
To reduce your OCD (or increase it..) over the phase issue, realize every crossover pole (classic inductor coil or capacitor) introduces 90 degrees of phase shift, so the usual 3 way 24BW or 24LR (4 pole) crossover introduces a minimum of 720 degrees of phase shift.
That phase shift can be eliminated using FIR filters, however listening to music (even on headphones with flat phase response) I can't detect the difference between "flat phase" and smoothly "wrapped" phase response with multiples of 720 degrees of phase shift over the audible spectrum.
Even though I am insensitive to phase wrapping, I have no doubt that others are.
Best of luck with your OCD ;^).
Cheers,
Art
I think I'm in the same boat with you, Art. Another data point (or maybe about 25 of them):
At an audio meeting a few years ago, I brought some of my speakers (the "Ported Small Syns") for a talk and demo about linear phase. I used a miniDSP "2x4HD" unit with two settings, "flat" (no eq applied, but signal goes through same hardware) and equalized to linear phase (same amplitude response). I showed the shape of square wave sweeps when played through various settings, then spent about 45 minutes playing various acoustic and vocal music tracks both ways. About half the people said they could her "no difference", maybe a third more weren't sure, and the rest said they could. But 3 of those who said they could preferred the version without the phase EQ. This was not at all a blind test (everyone knew which version they were listening to), but the result even still wasn't exactly a stunning argument for linear phase!
Took a while to find again, but Merlijn van Veen has an interesting article and video that can be used to determine for yourself the audibility of "phase wraps":
Detecting Phase Shifts (Video) - ProSoundWeb
After determining I couldn't detect the recorded "phase wraps" using headphones with flat phase, I could check off a lot of very time consuming items that had been on my audio "to do" list :^).
Art
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After that event, it occurred to me that there's not a lot of reason why people would be very sensitivite to this. What would be the evolutionary advantage of such an ability? Perhaps it might help to tell one bird sound from another, but it doesn't seem like something that would give a much better chance of survival.
By my (limited) understanding of how hearing works (bandpass filtering in the cochlea stimulating sensor hairs), we don't detect waveforms. We detect the envelopes of spectral content and those are unlikely to be very sensitive to when zero-crossings from acoustic pressure occur. Of course LOTS of phase wraps would become a lot of delay and that would start to have an effect on these spectral envelopes, so as usual it seems it would be a matter of degree.
By my (limited) understanding of how hearing works (bandpass filtering in the cochlea stimulating sensor hairs), we don't detect waveforms. We detect the envelopes of spectral content and those are unlikely to be very sensitive to when zero-crossings from acoustic pressure occur. Of course LOTS of phase wraps would become a lot of delay and that would start to have an effect on these spectral envelopes, so as usual it seems it would be a matter of degree.