| Forum: LAB Subwoofer |
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| Topic: LAB Porn!! |
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| Topic: Delta Subwoofer Array - Practical Implementation |
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| Delta Subwoofer Array - Practical Implementation [message #393659] |
Fri, 09 January 2009 09:47 |
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 nathan Lively
Messages: 4
Registered: December 2008
Location: Bratislava, SK |
Newbie |
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I think the Delta Array deserves it's own Topic because many people I work with would like to be able to use it. I am talking about the Delta Subwoofer Array described by Rog Mogale on page 15 of his Practical Guide To Bass Arrays.
http://www.voidaudio.com/pdf/bass%20guide.pdf
My question is, How is the displacement between boxes calculated?
Rog writes, "Do not be tempted to move the rear facing enclosures in a Delta Array forwards so they align with the front enclosures. Doing this destroys the arrays directional properties even if the delay times are changed... The array has directional properties only when the three elements form a triangle."
I tried to recreate this array in MappOnlinePro using 700-HPs, but the best configuration was not a triangle form, it was a line. See prediction below.
Rog says that his predictions are done with "122 cm high x 61 cm wide x 76 cm deep... double 18" reflex enclosure." But aren't 700-HPs similar enough to achieve similar results (117 cm x 57 cm x 76 cm, double 18" drivers)? What key information am I missing? Is the 'bass reflex' characteristic dominating?
www.nathanlively.com
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| Topic: hotrod |
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| Re: hotrod [message #393682 is a reply to message #393517 ] |
Fri, 09 January 2009 11:00 |
Marcel de Graaf
Messages: 9
Registered: November 2004
Location: Gilze-Rijen |
Newbie |
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Hello ivan (others),
Recently i read you did an A en B comparison bet ween
two subs. With the intention to tell which had the best
feeling "punch". Both had the same freq. respons below 90hz,
above the 90`s cabinet A had a higher level in freq. resp. and still cabinet B had the more punch. I was wondering what is the component that causes the difference? Is it in one of another measurable?
Recently i build myself two tapped horns. Picture from another forum: http://www.diyaudio.com/forums/showthread.php?s=&postid= 1560413#post1560413
Next thing i measured the frequency respons between a 18" vented sub and the tapped.
http://img194.imagevenue.com/img.php?image=19936_TH15_vs_Ven ted18_122_517lo.JPG
The measurement was indoors, both driven from the same channel, same amplitude of a P3000 EV.
The purple trace is the tapped, with a much a higher sensivity but still i had the feeling a had a lot more punch of the vented sub.
Greetings,
Marcel
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| Re: hotrod [message #393714 is a reply to message #393682 ] |
Fri, 09 January 2009 12:45 |
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 Ivan Beaver
Messages: 5602
Registered: January 2005
Location: Atlanta Ga area |
Has No Life |
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The two cabinets were similar, but very different. Both had roughly the same impedance 4 ohms.
Both were Tapped horns. One had a single 15" ceramic driver in the larger and the other had 2 12" neo drivers in a 20% or so smaller cabinet and a different Tapped horn arrangement. Each driver had a different "load" on it in the horn and the pair was used to "smooth things out a bit".
They kinda look like a push pull arrangement and are wired that way, but the way they load is not typical. Physical positioning kept them from both being in a "normal" arrangement.
The smaller cabinet with the smaller drivers went lower and louder and punchier.
I attribute most of the better performance to a "fine tuning" of the Tapped horn concept.
The differences that I saw in the measured freq response (there are all sorts of different measurements that can be done-with freq response being the most popular and easiest to understand) did not correlate to what my ears/body feeling was "telling" me.
I think we have yet to correctly define exactly what that "punch" is (in terms of measuring and quantifying).
Everybody knows when it is there, and there is no argument about that, but exactly what is causing it- is still up for debate-as far as I can tell.
Once we determine exactly what the "measurement" of it is, it will be a lot easier to design towards that goal.
I am open to all thoughts on the subject and wish I had a better understanding of the actual cause.
[Updated on: Fri, 09 January 2009 12:47]
Can I have some more talent in the monitors--PLEASE?
Ivan Beaver
dB Audio & Video Inc.
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| Re: hotrod [message #393735 is a reply to message #393714 ] |
Fri, 09 January 2009 13:23 |
Art Welter
Messages: 856
Registered: October 2007
Location: New Mexico |
Has No Life |
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Ivan,
Having read Tom Danley’s description of how the SH-50 can do a reasonable job of reproducing a square wave over about a decade range, I wonder if that might be a test for “punch” also?
I would have never thought of looking at square waves through a speaker, but it makes sense that they would be the hardest thing to do, and would show problems readily.
Have you ever used an oscilloscope (or some other similar tool) to look at the difference in reproduced waveforms between a “punchy” sub and a “less punchy” or “muddy” “slow” or whatever sub?
I would suspect that a punchy sub would have a more clearly defined stop and start of each waveform, and a muddy sub would have a slower start and some ringing after.
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| Re: hotrod [message #393770 is a reply to message #393714 ] |
Fri, 09 January 2009 14:49 |
Marcel de Graaf
Messages: 9
Registered: November 2004
Location: Gilze-Rijen |
Newbie |
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Talking about "punchfactor" of a sub is a very interesting subject.
I heard a lot off subwoofers, including a pair of labhorns i build in the past: http://www.speakerstore.nl/index.php?l=nl&pg=12&prjI D=25
These were definitely subs with huge about in the subregion. It also had the most quality (no doubt), but for me (disco) i wanted more punch.
The hardest punch i have ever heard comes from an old cabinet called MD215-HLF from a company called Master-Audio in Spain. This was a rear-loaded horn with two direct radiating 15" speaker.
I was really impressed when i heard it the first time. I have a complete document which includes some measurements, interest in it?
After that it is the 4pro 8001as from RCF for which i was also very impressed. This sub gives a lot op punch for a 18".
The 2 cabinets are entirely diferent systems. Changing the speakers in the cabinets (with the same T&S parameters) and the punchy feeling could be away. Therefore I also think much off the punch is catch up in the drivers itselfs.
Maybe the frequency respons is exactly the same, but there has to be a component (or a measurable value) that can show or explain that sound what we would want to hear or feel.
Marcel
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 Re: hotrod [message #393882 is a reply to message #393735 ] |
Fri, 09 January 2009 19:57 |
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Ivan Beaver
Messages: 5602
Registered: January 2005
Location: Atlanta Ga area |
Has No Life |
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That is a really good idea. It is easy enough to do, just finding the time is the real problem for me. I have a fair number of large fast paced projects going on right now.
I will keep it in mind when I get some time.
Can I have some more talent in the monitors--PLEASE?
Ivan Beaver
dB Audio & Video Inc.
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| Re: hotrod [message #393884 is a reply to message #393770 ] |
Fri, 09 January 2009 19:59 |
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Ivan Beaver
Messages: 5602
Registered: January 2005
Location: Atlanta Ga area |
Has No Life |
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| Marcel de Graaf wrote on Fri, 09 January 2009 15:49 |
The hardest punch i have ever heard comes from an old cabinet called MD215-HLF from a company called Master-Audio in Spain. This was a rear-loaded horn with two direct radiating 15" speaker.
I was really impressed when i heard it the first time. I have a complete document which includes some measurements, interest in it?
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I would like to see some measurements-whatever you have.
There have been several subs over the years that had a lot of punch. But generally they do not go very low and "wiggle your knees".
It takes both effects to have a great sub.
Can I have some more talent in the monitors--PLEASE?
Ivan Beaver
dB Audio & Video Inc.
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