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Old 15th September 2011, 10:19 PM   #171
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I love these less conventional ideas!

I have 4 10" ally bass guitar speakers from an old Hartke bass cab that im at a loss to know what to do with. Maybe this would be an interesting way of loading them?
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Old 15th September 2011, 11:22 PM   #172
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Hi -

I'm thinking of doing a quarter wave transmission line loaded PPSL. Is there any reason the transmission line should not exit next to the drivers in the plenum? (it would be split to give one exit for each driver). This would strictly be for HT SW use below 60 hz, and am thinking of using 20hz or so tuning for the transmission line.

TIA for any feedback.
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Old 15th September 2011, 11:38 PM   #173
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Quote:
Originally Posted by thoriated View Post
Hi -

I'm thinking of doing a quarter wave transmission line loaded PPSL. Is there any reason the transmission line should not exit next to the drivers in the plenum?...TIA for any feedback.
Hi there: TH's have one side of the driver(s) exiting into the horn mouth, so there seems to be no reason for not locating a TL port into the PPsl, althouigh others on this forum have expressed reservations, without backup data. ...regards, Michael
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Old 16th September 2011, 01:50 AM   #174
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Quote:
Originally Posted by j.michael droke View Post
Hi there: ... so there seems to be no reason for not locating a TL port into the PPsl, althouigh others on this forum have expressed reservations, without backup data. ...regards, Michael
Hi michael,

Agree.Maybe time to test for the crackpot index of whats been argued to be exceptional compared to other good sub implementations.

Crackpot index

As soon as you confine an TL terminus close to a driver front or rear side diaphragm: It turns into a T-TQWT lookalike setup (BP-like) as for the T-QPPSL:

A Thread for those interested in PPSL enclosures

...where I stated to use a lower input power than was simulated.

At a third of the presented input power maximum pressure at the rear side of the drivers would be no more than 165 Pascals/=~123 dB-SPL/at ~26Hz. Nothing to worry about if using quality drivers,IMO..

b
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Old 16th September 2011, 01:58 AM   #175
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I took a bad fall any have been out-of-touch for about three days now.

I will be back when I get better.
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Old 16th September 2011, 03:15 AM   #176
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djk.....hope you get better soon.
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Old 16th September 2011, 03:49 AM   #177
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Hi, DJK -

Hope you come back 100%+. Your input is always valued.

I am considering the quarter wavelength TL because my previous experience was that it seemed generally more neutral sounding than BR with still useful bass augmentation & not as rapid a rolloff below. but eventually, for hi quality audio, the delayed backwave started to bother me with music - I think this would be much less of a factor for HT use. If tuned for a quarter wave of 15-25 hz, could still have useful output down to as low as 8hz (with eq) where the K2 amp I plan to use with it cuts off.

Last edited by thoriated; 16th September 2011 at 04:02 AM.
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Old 16th September 2011, 04:38 AM   #178
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Quote:
Originally Posted by norman bates View Post
Click the image to open in full size.

perhaps here is some inspiration.
Yes, those are 18's with a 12" diameter port.
It is worth it.

Norman
Do you have any more pics of this build or atleast the bigger pictures showing the whole cabinet?
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Old 16th September 2011, 12:40 PM   #179
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I'm not sure what else you want to see............
I have no pics of the build (like 6 years ago), but I could get more pics (they are next door to me). If I remember, they were 48" wide x 36" deep x 22" tall. Again if I remember, it was either 16 or 18ft3 tuned to 27hz. The drivers were not in seperate enclosures, they shared the giant box.

Actually, in the pic, I can see the mdf splitting... oh well...........

Scott, I had some cheapie eminence gamma 15's. Sealed box f3 around 80hz, like no xmax. Djk will fill you in on why yours didn't work well. Don't put too much faith in simulations. Don't give up on ppsl, but you may have to give up on that box going up to 400hz nicely. The design is a bit trickier than I thought.

Norman

Last edited by norman bates; 16th September 2011 at 12:43 PM.
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Old 16th September 2011, 01:40 PM   #180
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WOW thats HUGE Norman.

I just wondered what it looked like in its location and all. Have been trying to see if anyone has done a more narrow PPSL cabinet design yet was all. I know yours isn't.
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