Not my kind of driver, but have the 94db Peerless XXLS 12" carsub been simmed...from statements about good TH specs, it could seem like a candidate fore TH 
http://www.tymphany.com/830877
http://www.tymphany.com/830877
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85audio, I have a TH-SPUD ready to seal and would like to know the opinions of the assembled experts on this topic.
My thought was to put felt, or carpet underlayment foam at the terminus of all of the long lengths. I have no specific reason other than it seems reasonable. I was leaning away from doing the entire path because at the throat end it seems like I would be taking up too much cross section.
I will be sealing it tomorrow, Sunday, so speak now, or forever hold your peace.
Paul
My thought was to put felt, or carpet underlayment foam at the terminus of all of the long lengths. I have no specific reason other than it seems reasonable. I was leaning away from doing the entire path because at the throat end it seems like I would be taking up too much cross section.
I will be sealing it tomorrow, Sunday, so speak now, or forever hold your peace.
Paul
Hi aceinc,
Earlier in this thread there are some pictures of the inside of the DTS-20 which show the use of a white foam pad (about 3/8" to 1/2" thick) stapled to the horn walls as a lining. It is questionable that this would apply to the SPUD though.
Also, in the "Double Driver Tapped Horn" thread there is a reference to pictures of the TH SPUD showing some batting being used immediately behind the speakers:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=136282&perpage=25&pagenumber=1
http://forums.audioholics.com/forums/showthread.php?p=492319
and:
http://forums.audioholics.com/forums/showthread.php?t=49678&page=8
Hope that helps, Regards
Earlier in this thread there are some pictures of the inside of the DTS-20 which show the use of a white foam pad (about 3/8" to 1/2" thick) stapled to the horn walls as a lining. It is questionable that this would apply to the SPUD though.
Also, in the "Double Driver Tapped Horn" thread there is a reference to pictures of the TH SPUD showing some batting being used immediately behind the speakers:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=136282&perpage=25&pagenumber=1
http://forums.audioholics.com/forums/showthread.php?p=492319
and:
http://forums.audioholics.com/forums/showthread.php?t=49678&page=8
Hope that helps, Regards
aceinc, I came to the conclusion that whatever the material is, it has to be some type of batting, just to make installation easier. I don't think you can use something like polyfill, because it wouldn't be secure enough(it might come loose inside the enclosure). A nice website you might want to check out is Zaph Audio. There is lots of good info on various drivers and free speaker plans. He also talks about dampening material at the bottom of the page. He says there is a dampening material called Whispermat which is a 1/3 of the price of Blackhole 5 and just as good, says egg crate foam is the worst there is, and a cheap material 1/2" carpet padding that should only be used when building ultra cheap speakers. I went to the local fabric store and have found what I think I have decided on using, 16oz polyester fiber batting, that looks to be about 1"-1.5" thick. I just wanted to get some input because once its in there and sealed up thats it. Shaun
aceinc said:
You can buy one for considerably less to see for yourself and report back.
Regardless, unless you build a ~exact replica, then its stuffing density won't necessarily be even remotely optimum for yours, so best to have a removable side plate to allow easy access to the entire path-length for fine tuning, same as you would for a TL.GM
Lining - Stuffing
Hi aceinc and 85audio,
I have not found any information as to treating the complete length of the horn, but using a thin absorbent foam lining makes sense. The loose polyester batting shown in the SPUD would probably only apply to the area right around the speakers.
William Cowan has provided some information as to lining the horn on his website and early as well as throughout this thread: see Posts #2741, #2849, #2867. There is lots of room here for you to provide some insight and measurements.
aceinc provided the DTS20 reference (foam lining) in Post #1677, djk in #2739.
The old method of making one side removable (foam gasket, caulk, screws) should provide access for experimenting, e.g.: Posts #1784-1789, GM in Post #2909.
Let us know what works best for you, Regards,
Hi aceinc and 85audio,
I have not found any information as to treating the complete length of the horn, but using a thin absorbent foam lining makes sense. The loose polyester batting shown in the SPUD would probably only apply to the area right around the speakers.
William Cowan has provided some information as to lining the horn on his website and early as well as throughout this thread: see Posts #2741, #2849, #2867. There is lots of room here for you to provide some insight and measurements.
aceinc provided the DTS20 reference (foam lining) in Post #1677, djk in #2739.
The old method of making one side removable (foam gasket, caulk, screws) should provide access for experimenting, e.g.: Posts #1784-1789, GM in Post #2909.
Let us know what works best for you, Regards,
G'day Oliver
I'd like to explore damping again one day. The plots shown on page 3 were of a slug of polyester at the velocity maxima for the first dip. The whole line was filled at that point. If the path was lined for it's full length, but only with 1" thich or so absorbent material it would probably work much better.
Cheers
William Cowan
I'd like to explore damping again one day. The plots shown on page 3 were of a slug of polyester at the velocity maxima for the first dip. The whole line was filled at that point. If the path was lined for it's full length, but only with 1" thich or so absorbent material it would probably work much better.
Cheers
William Cowan
Hi William,
I finally broke down and bought four of the MCM 55-2421 (10% off sale, Code: EMC086) to experiment with. Once they come in I'll have to find the time to make some saw dust, and measure a little.
Tom Danley obviously has the damping angle figured out. I hope you will again be able to share some of your results, your measurements and website have been a real help.
Regards,
Oliver.
I finally broke down and bought four of the MCM 55-2421 (10% off sale, Code: EMC086) to experiment with. Once they come in I'll have to find the time to make some saw dust, and measure a little.
Tom Danley obviously has the damping angle figured out. I hope you will again be able to share some of your results, your measurements and website have been a real help.
Regards,
Oliver.
Does anyone else have a problem with a hollow, echoing, reverby kind of sound?
I was wondering yesterday if 1/2" of so of felt would help.
Or if I had to do with cabinet vibrations, and I might need to double the walls, etc.
Or if it was a problem with the long path length, and indeed an "echo" heard down the "tunnel..."
I was wondering yesterday if 1/2" of so of felt would help.
Or if I had to do with cabinet vibrations, and I might need to double the walls, etc.
Or if it was a problem with the long path length, and indeed an "echo" heard down the "tunnel..."
hmmm.
could be, I've thought of that too...
I'm crossing @ 70hz, a ways below the -3db point (~100).
Using a 12dB pllxo.
I've heard going any higher causes more problems.
The real confusing part is that just pluging the THs in with the other speakers, no crossover @ all, in the same amp sounds better, more coherent...
could be, I've thought of that too...
I'm crossing @ 70hz, a ways below the -3db point (~100).
Using a 12dB pllxo.
I've heard going any higher causes more problems.
The real confusing part is that just pluging the THs in with the other speakers, no crossover @ all, in the same amp sounds better, more coherent...