What The .........? - Page 2 - AVS Forum
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DIY Speakers and Subs > What The .........?
mjaudio's Avatar mjaudio 03:48 PM 04-09-2013
That's exciting to hear.

I still have about 4 18" PR's lying around, would this be something worth looking into or is it worth the trouble only if you have 21" PR's?

I know there is a 6th order BP selection in WinISD but my brain shut down when it tried to process what I am doing, stupid brain. I have a RCF LF21N451 21" and a XXX 18" laying around right now not doing anything and a pair of SI 18" subs that are waiting for an enclosure.

Fatawan's Avatar Fatawan 06:22 AM 04-10-2013
Quote:
Originally Posted by mjaudio View Post

That's exciting to hear.

I still have about 4 18" PR's lying around, would this be something worth looking into or is it worth the trouble only if you have 21" PR's?

I know there is a 6th order BP selection in WinISD but my brain shut down when it tried to process what I am doing, stupid brain. I have a RCF LF21N451 21" and a XXX 18" laying around right now not doing anything and a pair of SI 18" subs that are waiting for an enclosure.

You would have to model it and see. I did a "combo" model where I was using the 6th order BP and the PR facilities in WinISD at the same time to get tuning and chamber sizes. Which PR's do you have?
Ricci's Avatar Ricci 12:27 PM 04-10-2013
There is a freeware program called SubSimulator (I think) that will model these and even 8th order cabs. It is about as easy as winisd once you get used to it. I don't remember the actual link to it.

Or there is Akabak if you feel froggy...
mjaudio's Avatar mjaudio 01:14 PM 04-10-2013
Quote:
Originally Posted by Fatawan View Post

You would have to model it and see. I did a "combo" model where I was using the 6th order BP and the PR facilities in WinISD at the same time to get tuning and chamber sizes. Which PR's do you have?

I was messing around a little on WinISD using 6th order BP's but really have no idea what I am doing right now. Are the chambers tuned to the same frequency or is one tuned low and the other higher, say 15hz for the back chamber and 40hz for the front?

I have a pair of Exodus 18" PR's with the weight kit and a pair of Mach 5 18" PR's but they are already tuned to 18hz per Mark and I think it's glued in so I might not be able to change the tune. Jogging my memory I forgot I also have a pair of TC Sounds 15" VMPS but I am thinking the 18's are the way to go especially since I need 3?
mjaudio's Avatar mjaudio 01:15 PM 04-10-2013
Quote:
Originally Posted by Ricci View Post

There is a freeware program called SubSimulator (I think) that will model these and even 8th order cabs. It is about as easy as winisd once you get used to it. I don't remember the actual link to it.

Or there is Akabak if you feel froggy...

Thanks man, I will have to look those up as well.
Fatawan's Avatar Fatawan 01:45 PM 04-10-2013
Quote:
Originally Posted by mjaudio View Post

I was messing around a little on WinISD using 6th order BP's but really have no idea what I am doing right now. Are the chambers tuned to the same frequency or is one tuned low and the other higher, say 15hz for the back chamber and 40hz for the front?

I have a pair of Exodus 18" PR's with the weight kit and a pair of Mach 5 18" PR's but they are already tuned to 18hz per Mark and I think it's glued in so I might not be able to change the tune. Jogging my memory I forgot I also have a pair of TC Sounds 15" VMPS but I am thinking the 18's are the way to go especially since I need 3?

Small chamber in front tuned to higher frequency than big chamber in back. If you really mess up on the model, you can get the response to look like sally the camel(2 humps). I may get that Sally look, I don't know. I am putting REW on my laptop right now.
Fatawan's Avatar Fatawan 07:24 AM 04-13-2013
Houston, we may have a problem. It was late when I finally got REW going on my new laptop. I only ran a couple sweeps, but it appears my front chamber is peaking around 36 Hz. That is where the model would indicate the tune to be when the chamber volume is 2.9cf. That would indicate to me that my foam did nothing to take up the excess volume. I thought it would reduce the volume down to 1.6cf or so, but it appears I was wrong. Anyone have any thoughts on that? Back to the drawing board.....
brian6751's Avatar brian6751 07:58 AM 04-13-2013
Cut small panels and seal off each of those foam chambers using PL premium ?
Fatawan's Avatar Fatawan 08:26 AM 04-13-2013
Quote:
Originally Posted by brian6751 View Post

Cut small panels and seal off each of those foam chambers using PL premium ?

Yea, that is what I was thinking too.

Here are the graphs--all were done with a 20Hz BUT12 filter in place to protect the innocent until my MiniDSP is in place

The front PR



A sum of both rear PRs



and finally, a sum of all three radiators


Fatawan's Avatar Fatawan 08:47 AM 04-14-2013
Well, the powers of the miniDSP have made this look a lot better. Some more fun with REW now:

I added the miniDSP to the equation(was using the DCX2496 before--its now out of the loop). I put in a 12Hz LR24 HPF. I also added one wide PEQ cut of 5db centered at that 36Hz peak. Now watch the magic!

First, the front radiator alone



Here are the individual traces of the two PRs in the rear chamber



Now if I sum both rear chamber outputs and put them on the graph with the front PR trace



To wrap it up, I sum the output of the front PR with the summed outputs of the rear PRs and this gem emerges



So I end up with a "band" that is narrower than I had originally intended, but I may just live with it. It will provide some serious output in that 18 to 60Hz region before my room's own output additions.
Fatawan's Avatar Fatawan 04:26 PM 04-17-2013
I added another sub to the front of my room(LMS 5400 15" with two 18" PRs, same tune as this new sub), plus I have 4 sealed Rythmiks in the back of my room. I used the miniDSP to get the front two subs to play well together after I got the best graph I could from moving subs around. I consider that SUB A as far as Audyssey Multi EQ XT32 is concerned. The 4 Rythmiks stacked in back are SUB B. I ran Audyssey, and here is the result at my main listening position:




I can live with that. I am going to listen now and see if I like this combination or not.
N8DOGG's Avatar N8DOGG 04:52 PM 04-17-2013
good looking graphs!!! I bet it sounds great.
coctostan's Avatar coctostan 02:25 PM 04-18-2013
That is exceptional Fatawan. Have you taken measurements across a few seats?
Fatawan's Avatar Fatawan 12:13 PM 04-19-2013
Quote:
Originally Posted by coctostan View Post

That is exceptional Fatawan. Have you taken measurements across a few seats?

I was having people over that night, so it was a quick three-position Audyssey run, one measurement at the main listening position to make sure it was ok, then rush to put it all away. I'll do some more later.
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