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WinISD vs Unibox - Modelling a Dual Opposed LMS-R 15

post #1 of 13
Thread Starter 
Hello All,

So I got both drivers and some plywood. I plan on putting together an early me-2-me Xmas present.
I will be powering them with either a Inuke 6k DSP or LG clone 10Q / MiniDSP combo.
Each driver will run at 4ohm to a amp channel. I was hoping to run about 1500W into each driver.

Being playing with models for over a week now and getting some strange results between the two programs.
Historically I noticed that most people use WinISD in their models but Scott normally uses Unibox.

Here are the outputs from Unibox




Based on a minimal leakage and stuffed box model, it claims that 118L net should yield around 0.7 Qtc

Here are the outputs from WinISD for 118L box (system power is 3000W, 2 Drivers, Parallel)





What is the value of importance one should give to the Ql (Rate of Leakage) and Qa (Absorption) settings ?

Changing these values has a major impact on Cone Excursion and predicted Qtc but I have never seen anyone saying they change these values in WinISD.

Using the WinISD defaults to get a Qtc of 0.7 I need a 210L box. (power reduced to 2000W)



What size box should I be looking to build taking into account

- Qtc in the lower 0.7xx range
- 1500W per driver @ 4Ohms
- Cone excursion below 10Hz acceptable

Need some help and input here from the collective. It is quite possible I can not see the wood from the trees with the solution clearly in front of me.

Should I be modelling the drivers in series maybe as that provides very different values?

Thanks.
post #2 of 13
First of all, just skip this part. Lol.

You're going to be using the iNuke6k which has been documented to have some rolloff already by 10hz let alone below that. So right now you're looking at (in the sims) an already safe amount of excursion over the drivers rating. Now include the signal rolloff that you will have (nearly all of us do, even if we try not to) significant rolloff of signal in that range where excursion is the highest.

So if you are worried about that excursion <10hz (regardless of air loss simulation) I'll tell you right now.... complete non-issue. You're safe. smile.gif

Now... the question of air leakage. Hmm.. if the question about the effects of it... I could go on forever but to make it real simple, we all want NO air leaks. I would model for zero to minimal leakage. I would always model for both when doing a resonant alignment (vented/passive radiator) because those kinds extra non-linearities and such can and will affect the response. With sealed... not as important that it affects the system by much. BUT... airleaks themselves are not good to have.
post #3 of 13
Quote:
Originally Posted by Nuno C View Post

What is the value of importance one should give to the Ql (Rate of Leakage) and Qa (Absorption) settings ?

Please take a look at this thread. I provided laser measurements of cone excursion. It is safe to set Ql to a high value. Leakage is no problem in real world CB subwoofers.
post #4 of 13
Thread Starter 
Thanks for the link FoLLgoTT - Very cool thread. Good to know it does make a big difference and even better to know that it matches close to reality as well.

Based on your observations:
- Heavy Fill, Walls Covered, Minimal Fill, No Fill. These correspond to a Qa of 5, 20, 80, 120.
- Minor Leaks, Minimal Leaks, No Leaks. These correspond to a Ql of 20, 30, and 50 respectively.

I have updated the WinISD models with - Heavy Fill (Qa of 5) with No Leaks (Ql of 50)




Based on my plan to wire each driver to 4Ohms on a separate amp channel - which box model is more accurate?
post #5 of 13
Thread Starter 
Thinking I might be over thinking this. ... confused.gif
I am pretty close to ideal, so I reckon I should go ahead, call it a day and build this 120L box.



Will get started this weekend unless someone comes back with a better idea.
post #6 of 13
I have dual opposed LMS-R 15's in a ~130L box driven by the inuke 6000dsp. They can easily take full power to clipping at any frequency without any signs of danger or bad noises.

Great sounding setup, more similar than different compared to one of my sealed LMS ultra's, just less potent at the lowest freq's (amp roll off compared to the clone). It's nice to be able to run it full tilt without worry of excursion though.
post #7 of 13
Thread Starter 
Quote:
Originally Posted by cubalis2 View Post

I have dual opposed LMS-R 15's in a ~130L box driven by the inuke 6000dsp. They can easily take full power to clipping at any frequency without any signs of danger or bad noises.

Great sounding setup, more similar than different compared to one of my sealed LMS ultra's, just less potent at the lowest freq's (amp roll off compared to the clone). It's nice to be able to run it full tilt without worry of excursion though.

Thanks for your feedback Cubalis. That is great news and I no longer have to worry about setting up any power limiters in the DSP. I already started making the braces and front baffles today.
Will create a build thread once I have made some decent progress.
I assume you running each driver at 4Ohm off the two iNuke 6k channels.... is that correct?
Strange you mention that the dual-opposed is 'less potent at the lowest Freq's then one of your Ultra's'. I was hoping the two 15 would outperform an Ultra. Lucky for me I don't have a comparison so I won't know what I am missing. rolleyes.gif

Lastly, you mentioned a clone, have you run the 130L box off the clone? I have a 10Q Sanway clone and thinking I might use that instead of the iNuke 6k. The iNuke 6k is good for about 1800W at 4Ohms 'bass duty'.
From the AVS clone thread it looks like the 10Q Clone should be able to reach around 2200Wpc @ 4Ohms. The additional power does not raise any red flags so looking forward to seeing/hearing a comparison.
post #8 of 13
Quote:
Originally Posted by Nuno C View Post

Thanks for your feedback Cubalis. That is great news and I no longer have to worry about setting up any power limiters in the DSP. I already started making the braces and front baffles today.
Will create a build thread once I have made some decent progress.
I assume you running each driver at 4Ohm off the two iNuke 6k channels.... is that correct?
Strange you mention that the dual-opposed is 'less potent at the lowest Freq's then one of your Ultra's'. I was hoping the two 15 would outperform an Ultra. Lucky for me I don't have a comparison so I won't know what I am missing. rolleyes.gif

Lastly, you mentioned a clone, have you run the 130L box off the clone? I have a 10Q Sanway clone and thinking I might use that instead of the iNuke 6k. The iNuke 6k is good for about 1800W at 4Ohms 'bass duty'.
From the AVS clone thread it looks like the 10Q Clone should be able to reach around 2200Wpc @ 4Ohms. The additional power does not raise any red flags so looking forward to seeing/hearing a comparison.

That is correct, each driver on it's own channel on the inuke.

I haven't run it off my 14k clone yet, and don't know if I ever will. I actually have a second identical box built and painted, just haven't got around to ordering two more LMS-R's due to moving, life, etc. If/when the second subs is complete I will most likely pick up the 10k clone as I prefer one amp over two... although the inuke NU4-6000 could be an interesting choice - basically two 6000's slapped together.

It has been a few months since I did the a/b comparisons, but when I drove the single LMS ultra 18 off of the ep4000 (~2kw) and compared it to the dual LMS-R 15's on the inuke6k, I found them to be very comparable. The duals had a touch more output before clipping, and went every bit as loud down low according to my spl meter. Once I moved to the 14k clone the ultra's pulled ahead. The LMS-R's could surely take more power than the inuke 6k can output, but then some protection would certainly be wanted to prevent any overexcursion down low.

I should really take advantage of PE's cyber monday sale and grab another pair of LMS-R's... I think this thread may have just cost me some money biggrin.gif
post #9 of 13
This thread was officially expensive for me. I ordered another pair of the LMS-R's to finish off the long ago built box.

Now I need to decide if I should gamble with a clone 10Q or buy another inuke.
post #10 of 13
Thread Starter 
SUCKER !!!!! biggrin.gif

My work here is done.... (at least you saved $50 on the PE special)


I already started my build over the weekend. Should have it finished by the 15th hopefully.
I will be happy to run some tests and give some impressions comparing the two but my set-up will be different than yours.
I got a DO Dayton 18 460HO in a 240L and shortly will welcome the DO LMS-R in 120L.
I'm going to do it anyway. I am on 230V however... not sure how much a difference that would make.
Right off the bat... I have noticed the lower noise floor on the 10Q.
With no input and the gain at 75% the woofers make a hiss on the iNuke that is not present on the Clone.

How many subs you going to be running once complete?
post #11 of 13
Haha, I actually added some cables, speakon connectors, and a wireless sub receiver/transmitter (for the living room) and brought the total up to $1k, then used the $100 off cool.gif

In the theater I will now have the 4 LMS-R 15's in two dual opposed boxes, and 2 sealed LMS Ultra 18's. Either both ultra's or both dual opposed LMS-R boxes will be nearfield directly behind the single row of seats to be crossed over at ~50Hz, whichever ends up fitting better. I have used the same nearfield setup with the ultra's in the past, and love the tactile response. I would ideally want the Ultra's up front on 'display', as the boxes were made by Nathan Funk and are quite the lookers. The DO 15 boxes on the other hand are simple black painted mdf 'utilitarian' style biggrin.gif

Please do let me know your impressions of the inuke vs 10Q clone. I would like to simplify the amp situation and just run the clones, but since I already have one inuke it would be easier to add another than try to sell it and pick up a clone. With you having both amps on hand I look forward to getting some feedback from you about it. Interesting about the hiss with the inuke, I will try mine tonight and check for it.
post #12 of 13
I picked up another inuke NU6000 (non dsp - have the minidsp anyways) for a steal on ebay, so I'm going that route for the time being. Still very curious about the direct comparison though.

No hiss on the inuke/lmsr combo for me until I hit ~ 90% gains, just fyi.
post #13 of 13
if you get the itch to go big with a giant tapped horn, the lmsr works in something like that pretty well. :-)
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