Dual RL-p15 D2 driver DIY..

**Ilkka** · 05 March 2006, 11:13 Sunday

Originally posted by Jack Gilvey

Yeah, cool! It used to be that a mono Bassis would have the same chassis as the stereo. Nice price, too. Does the DEQ2496 have shelving boost?

Yes it has. Although FBQ2496, which Steve has, doesn't have. Of course DEQ2496 is quite a lot more expensive too.

I'm pretty sure that the "Hz/2" merely halves the Fs, making the range 15-65Hz, this was the option decribed to me. I can't imagine why it would be "half-calibrated" any other way, halving the boost, Q, etc., I don't see the purpose of that.

I'm with you on this.

**steve nn** · 05 March 2006, 11:31 Sunday

I can't imagine why it would be "half-calibrated" any other way, halving the boost, Q, etc.,

I don't know, but I'll be sure to confirm. I think I'll find that your correct though...It sure seams like Phil said something about the boost. Heck I could just take some NF measurements and find out in a jiff couldn't I?

**Ilkka** · 05 March 2006, 11:50 Sunday

Originally posted by steve nn

I don't know, but I'll be sure to confirm. I think I'll find that your correct though...It sure seams like Phil said something about the boost. Heck I could just take some NF measurements and find out in a jiff couldn't I?

If you would like to do some NF work, I would like you to measure the "pure" FR for one of your subs (of course you can do both, then we see if there are any differences).

Take everything offline, meaning that you are only feeding the amp with a clean signal, no FBQ, no BASSIS online.

Use low distance, a few inches from the cone is ok. Keep the distance and MV constant and measure the FR from as low as you can up to at least 100 Hz. Don't use any corrections, just post the pure numbers here. I'll do the rest.

**steve nn** · 05 March 2006, 12:39 Sunday

I just did a little NF (1-2") test and this is what I came up with.

15 Hz no boost and full boost. 64dB 76dB No FBQ2496 in the mix
20 Hz....................................72dB 80dB
40 Hz....................................90dB 88dB No typo and no correction added.

If you would like to do some NF work, I would like you to measure the "pure" FR for one of your subs (of course you can do both, then we see if there are any differences).

Sure, I'll go ahead and do both.

**Ilkka** · 05 March 2006, 13:05 Sunday

Originally posted by steve nn

I just did a little NF (1-2") test and this is what I came up with.

15 Hz no boost and full boost. 64dB 76dB No FBQ2496 in the mix
20 Hz....................................72dB 80dB
40 Hz....................................90dB 88dB No typo and no correction added.

Of course Qb and Qs will also affect on these, but it looks like that you have only 12 dB of boost.

Sure, I'll go ahead and do both.

Cool. And I forgot to say, but take readings as least using 5 Hz increments, maybe even less (at least around the system resonance at ~40 Hz).

**steve nn** · 05 March 2006, 18:58 Sunday

Of course Qb and Qs will also affect on these, but it looks like that you have only 12 dB of boost.

From past measurements that's what seamed to equate out. My thinking on Qb was that I have always liked my Q around .6 to .7 in the past, so maybe this setting is half also??.. considering I'm favoring the 1. setting. With music they sound nice from .5 to 1. though. Do you know the Q of the Ultra in the 16 Hz tune? Wouldn't it come in around .7 with the Maestro coming in at around .55 to .6?

but take readings as least using 5 Hz increments, maybe even less (at least around the system resonance at ~40 Hz).

No problem. I'm viewing more today to firm up my impressions with the new Q setting. I should have a set of numbers tomorrow as long as no one is home to kype the computer from me. Thanks

**Ilkka** · 05 March 2006, 19:43 Sunday

Originally posted by steve nn

From past measurements that's what seamed to equate out. My thinking on Qb was that I have always liked my Q around .6 to .7 in the past, so maybe this setting is half also??.. considering I'm favoring the 1. setting. With music they sound nice from .5 to 1. though. Do you know the Q of the Ultra in the 16 Hz tune? Wouldn't it come in around .7 with the Maestro coming in at around .55 to .6?

We don't talk about Qtc with vented subs, but it would be more than 10. Yes, that's a ten. 8O

Maestro is said to be less than 0.6.

**steve nn** · 05 March 2006, 20:28 Sunday

but it would be more than 10. Yes, that's a ten. 8O

Good Grief!! well!..I guess that explains that then. lol It's no wonder that I like the 1. setting then, along with running reference Klipsch as long as I have. They need a little softening you know.

Top sub 15hz 67 16-69 17-71 18-73 20-76 22-80 25-83 28-86 30-87 35-91 38-93 40-94 43-95 45-95 48-96 50-96 55-96 60-95 65-95 70-94 75-93 80-92cross 85-90 90-88 95-87 99-86 no correction applied

BTM sub 15hz 67 16-69 17-72 18-74 20-77 22-80 25-83 28-87 30-89 35-92 38-94 40-95 43-96 45-96 no48 50-97 55-97 60-96 65-95 70-94 75-93 80-92cross 85-90 90-88 95-87 99-86 no correction aplied

**Ilkka** · 05 March 2006, 21:44 Sunday

Thanks Steve! I'll see what I can come up with.

If you want, you could plot the other one without any crossover (or set it at least as high as it goes).

Also if you can go over 100 Hz, would be cool (150 Hz is enough). You can use big increments, 10 Hz.

**ThomasW** · 05 March 2006, 23:28 Sunday

We don't talk about Qtc with vented subs, but it would be more than 10. Yes, that's a ten.

Dan Wiggins has a way to create low "Q" ported boxes. Here's a snip from an email exchange I had with him in 2000 about one such design....

3.25 cubic feet
Isobaric pair of Tempests
Tune to 14 Hz
Stuff with 48 ounces of polyfill

What will you get:

A box that has a second order roll-off to 12 Hz (sealed box rate)
A box that has a Qtc of 0.5 (critically damped; tightest bass you can get)
A box with an Fc of 20 Hz

The response is often considered the "ideal" audiophile response: critically damped response with a corner frequency of 20 Hz.

Why do the vented versus a pure sealed? More headroom. As compared to a sealed Tempest, you'll have between 3 and 7.2 dB MORE SPL capability with the vented alignment, from 22 Hz down to a bone-rumbling 11 Hz. That means you get the sealed sound, with the benefit of the vented SPL capability.

Additionally, because the box is SO small, it takes a FULL 750W linearly. And, in a typical room, you should have a final system F3 around 16 Hz. F8 would be down around 11 Hz. DEEP bass output!

Worth considering, IMHO.

Dan Wiggins
Adire Audio

>>snip

Low Qtc ported designs can't be "modeled" using standard software programs. Dan uses the filter formulas for the electrical circuit of a box and inserts the "Q". I don't know exactly what he's doing....:wink:

**steve nn** · 06 March 2006, 16:41 Monday

If you want, you could plot the other one without any crossover (or set it at least as high as it goes).

I'm not quite sure what you mean by other one Ilkka? I gave you a set of numbers with sub 1 and sub 2. Same MV, 1" distance yawda-yawda.. I can get the cross up to 150, but my disk only goes to 99 Hz...15 Hz is as deep as it goes. I cant burn and play out in the main (older dvd player) but I can in the den, so if it's really important, I can unhook the PCi in here and run a cable out to the main. I have the same crossover capability here, but your going to have to make a little case for me doing so. I'll do it one way or another though if thats what you want. Geeze, I sure backtracked there awfully fast didn't I. :scratchhead:

Dan Wiggins has a way to create low "Q" ported boxes.

Interesting.

**Ilkka** · 06 March 2006, 17:03 Monday

Originally posted by steve nn

I'm not quite sure what you mean by other one Ilkka? I gave you a set of numbers with sub 1 and sub 2. Same MV, 1" distance yawda-yawda.. I can get the cross up to 150, but my disk only goes to 99 Hz...15 Hz is as deep as it goes. I cant burn and play out in the main (older dvd player) but I can in the den, so if it's really important, I can unhook the PCi in here and run a cable out to the main. I have the same crossover capability here, but your going to have to make a little case for me doing so. I'll do it one way or another though if thats what you want. Geeze, I sure backtracked there awfully fast didn't I. :scratchhead:

By other one I just meant your other sub. No need to measure both of them, since they seem pretty identical. Those measurements are ok, but I would like to see other one measured without any crossover (or at least at 150 Hz). I would like to see the "pure" FR without any filtering, now the 80 Hz XO distracts me just a bit. 99 Hz is fine, but if it's no trouble, up to 150 Hz would be better. 8)

**steve nn** · 06 March 2006, 17:28 Monday

Do you want me to calibrate first? I'm not totally sure where my calibration was with the first set I gave you...well I know within a dB or so. I do know MV.. If I go with the same MV and calibration with the 150 Hz cross, it's going to come in louder, but maybe that doesn't matter anyway? Your looking to see how it performs over the range and not so worried about everything being constant (MV, calibration) with the last set of numbers. My disk only goes to 99 Hz though.

EDIT> I do know what calibration was..Wher it's at now!

**Ilkka** · 06 March 2006, 17:53 Monday

Originally posted by steve nn

Do you want me to calibrate first? I'm not totally sure where my calibration was with the first set I gave you...well I know within a dB or so. I do know MV.. If I go with the same MV and calibration with the 150 Hz cross, it's going to come in louder, but maybe that doesn't matter anyway? Your looking to see how it performs over the range and not so worried about everything being constant (MV, calibration) with the last set of numbers. My disk only goes to 99 Hz though.

EDIT> I do know what calibration was..Wher it's at now!

If you take new readings starting from 15 Hz, MV doesn't matter. But I guess MV was pretty good, above 60 dB at 15 Hz is a must.

**ThomasW** · 06 March 2006, 17:59 Monday

The RL-p 15 has a fairly high Le, that's going to roll-off top end. One can see that roll-off starting at 60Hz-65Hz in the measurements already posted

**Ilkka** · 06 March 2006, 18:06 Monday

Originally posted by ThomasW

The RL-p 15 has a fairly high Le, that's going to roll-off top end. One can see that roll-off starting at 60Hz-65Hz in the measurements already posted

Yes, I know. That's why I would like to bypass the XO, to see the effect of Le.

Steve, did you call Phil?

**steve nn** · 06 March 2006, 18:13 Monday

If you take new readings starting from 15 Hz, MV doesn't matter. But I guess MV was pretty good, above 60 dB at 15 Hz is a must.

You cant be serious? MV was at -41.. although it be a heated up sine disk.

**Ilkka** · 06 March 2006, 18:14 Monday

Originally posted by steve nn

You cant be serious? MV was at -41.. although it be a heated up sine disk.

Above 60 dB on your Radio Shack Steve!

:

**steve nn** · 06 March 2006, 18:16 Monday

Steve, did you call Phil?

Whoops! No I totally forgot. Remind me tomorrow if I forget.

ops:

**steve nn** · 06 March 2006, 18:18 Monday

Above 60 dB on your Radio Shack Steve!

:2fingers:

**steve nn** · 06 March 2006, 18:51 Monday

I gave Phil (Marchand Electronics Inc) a call, but I'm afraid I'm a little late with there being a three hr time difference.

**steve nn** · 06 March 2006, 19:54 Monday

but I would like to see other one measured without any crossover (or at least at 150 Hz).

150 Hz cross. Everything else constant...no correction

15hz-67 16-69 17-71 18-73 20-77 22-80 25-83 28-87 30-89 35-92 38-93 40-94 43-96 45-96 48-97 50-98 55-98 60-98 65-98 70-98 80-97 85-97 90-97 95-96 99-96

With correction it looks like about 81dB at 15 Hz, on up to 100dB at 50 Hz, and then a downward trend to 97dB at 99 Hz.

**steve nn** · 07 March 2006, 16:14 Tuesday

Steve, did you call Phil?

Ok I was able to track Phil down today and here is what he shared with me. The Mono BASSIS is more of a specialty order item, but a product they have sold in the past. The front panel changed about a year ago and the pic I posted reflects the change. My understanding is the stereo BASSIS has the new look also. He thought it to be a good idea if there is more of a call for the 1/2 calibrated Mono BASSIS in the future, to have the front Fs Hz reading reflect the true setting, so one would not need to compensate. Everything else in regards to the readings are the same and not 1/2 calibrated. If I were to move ny Fs Hz setting up, I would realize the full 24dB boost that's available. I knew this had a affect on the boost, but lacked the knowledge to associate it with available boost. The unit normally goes for $400 (when sold) and I received the discounted price, as stated before, because the stereo BASSIS was on special at a $100 discount off of the normal $600 retail price. I think that covers everything?

Above 60 dB on your Radio Shack Steve!

Maybe I should rephrase just in case?? If I upgraded my measuring equipment.. I wouldn't have the pleasure of working and rough housing with you Ilkka.

:

**Ilkka** · 07 March 2006, 16:54 Tuesday

Ok, cool. Now that we cleared that out, we can start to tune your settings.

Your NF measurements seem to correlate well with the simulations. So Q is around 0.55 and Fs is around 40 Hz. So I would like you to set BASSIS accordingly, Qs to 0.55 and Fs to 80 Hz.

If you only like to use a small boost like 6 dB, it leaves you with only a fairly small range of Q's you can get. Meaning your Qb can be around 0.5-0.7, any other values are prohibited, because the LT can't work with them properly.

I would not adjust the Q at all, it's just perfect. So I would set both Qs and Qb to 0.55.

I would like you to try out these settings and tell me how you like them. If taking those NF measurements isn't too much of a trouble, you could plot your response with those settings on.

**steve nn** · 07 March 2006, 17:32 Tuesday

So Q is around 0.55

It's nice to have some finality to this. Thanks for confirming.

I would not adjust the Q at all, it's just perfect. So I would set both Qs and Qb to 0.55.

In adjusting the Qb from 1. to .55 aren't I going to be changing the Q, or is the new .55 Qs setting going to negate that?

I would like you to try out these settings and tell me how you like them. If taking those NF measurements isn't too much of a trouble, you could plot your response with those settings on.

Most definitely, I just want to be sure I'm understanding you correctly first.

**Ilkka** · 07 March 2006, 18:05 Tuesday

Originally posted by steve nn

It's nice to have some finality to this. Thanks for confirming.

In adjusting the Qb from 1. to .55 aren't I going to be changing the Q, or is the new .55 Qs setting going to negate that?

Most definitely, I just want to be sure I'm understanding you correctly first.

Qs is the old Q, defined by your subwoofer IE the steepness of the response. Qb is the new Q defined by the BASSIS. As your old Q is already pretty ideal (0.55), I wouldn't change it to any direction.

**steve nn** · 07 March 2006, 18:27 Tuesday

I would not adjust the Q at all, it's just perfect. So I would set both Qs and Qb to 0.55.

Ok that's what I'll do with not adding more than 6dB of boost. With Fs at 80, I wouldn't think I would want to add anymore than that knowing how it affects SPL. This is going to be interesting..to me anyway.

**Ilkka** · 07 March 2006, 18:33 Tuesday

Originally posted by steve nn

Ok that's what I'll do with not adding more than 6dB of boost. With Fs at 80, I wouldn't think I would want to add anymore than that knowing how it affects SPL. This is going to be interesting..to me anyway.

Yeah, you should take measurements and try to set-up the settings so that you will get a smooth slope, no peaks anywhere and as good extension as possible.

**Dennis H** · 07 March 2006, 19:16 Tuesday

Qs to 0.55 and Fs to 80 Hz

I think that's a typo. Fs is 40 Hz.

**steve nn** · 07 March 2006, 19:26 Tuesday

I think that's a typo. Fs is 40 Hz.

Half calibration would come out to 40 Hz yes. I just recalibrated and am plopping in LOTR. I could tell with calibrating that Ilkka is on the right track. :E

**Ilkka** · 07 March 2006, 19:27 Tuesday

Originally posted by Dennis H

I think that's a typo. Fs is 40 Hz.

Real Fs is 40 Hz, but Steve has to use 80 Hz.

**Ilkka** · 07 March 2006, 19:29 Tuesday

Originally posted by steve nn

Half calibration would come out to 40 Hz yes. I just recalibrated and am plopping in LOTR. I could tell with calibrating that Ilkka is on the right track. :E

Sounds very good. :T

**steve nn** · 07 March 2006, 20:29 Tuesday

Ilkka, Ilkka..Ilkka! I just don't know what to say? I just skimmed through LOTR and not a hint of harshness. The bass was absolutely beautiful. Talk about impact! In the elephant scene when the footsteps resonate..I would expect to have to eq the top end out, but it came across very nice not to mention the low FR impact. I felt it was good before, but room for improvement..well you just put me forward to a level that I don't think I've ever experienced before??.. Maybe the dual Ultras? With out tweaking from your suggested settings (4dB on the boost) and no FBQ/BFD, the bass presentation was absolutely stellar.

Might you be able to tell me why the SQ was a little off with just the amp or FBQ and amp? It was good don't get me wrong and of course needed a little taming, but there was a little harshness in some of the presentation that I wouldn't of expected. I'll be interested in measuring the response and seeing what we're looking at. Anyway!.. I now am a firm advocate of the BASSIS and the importance of setting it up correctly, not to mention the FBQ for that matter. Yes still much to listen to and most likely a little gain in tweaking, but I feel totally confident I'm on solid ground now. :T :nos:

**roadrash** · 08 March 2006, 09:21 Wednesday

Hello steve.
great job with your subs.
i was wondering how you get 3.65 cu/ft for a 22" box.
i calculate it to be 6.16 cu/ft so i must be doing something wrong.
i am a total noob at diy sub building but am interested in maybe building one.
i thought that you multiply lenght x width x height to get the enclosure volume
but i cant seem to get anywhere near 3.65
please help a total noob.

**Bent** · 08 March 2006, 09:46 Wednesday

22" cubed = 6.16 ft^3, not a complicated calculation - however the driver, when mounted in the box only "sees" the internal volume, which if steve used doubled up 3/4" mdf makes his internal dimensions 19"^3 = 3.96 ft^3 (less than 6.16ft^3... ) Taking into acount the fact the the internal bracing will occupy some of this space, and that tye driver will also occupy some more of this space... you get the idea.

**steve nn** · 08 March 2006, 15:37 Wednesday

http://www.the12volt.com/caraudio/boxcalcs.asp#rec

Here is a great site that DIY Jack G turned me on to. There are plenty of others, but I have found this site to be quite helpful and easy to navigate. If you plug in the numbers roadrash and minus .21 cu ft for the driver and little for bracing, you'll come up with around 3.8 or so. My enclosure is 1.25 thick along with being a 22" cube. The baffle is 2" thick. By the way...how did you come up with roadrash?

I had a chance to view a little of "THE INCREDIBLES" last night after the LOTR. It was around 6:30 so I prematurely closed it down due to the neighbors. Another 5 minutes and Judy would have been knocking on the door for certain! I'm not sure how to describe it, but it comes across to me as the most behaved bass I have ever heard along with outstanding SPL in the lower regions. When Mr. Incredible stops the train, every track popping is felt along with all the slam that us bassheads crave. The low FR scenes are as realistic as I could hope for. It really seems like what I have been used to, to be honest with you in my past 16 Hz config... while presenting it with a little more finesse.

I wonder if Ryan would benefit in trying out the BASSIS with some assistance from Ilkka or Thomas? I sure know I wouldn't have came up with the settings Ilkka suggested and somehow it squared away the small percentage of bass that was bothering me SQ wise. Of course SPL has benefited, no doubt about it!

**ThomasW** · 08 March 2006, 16:11 Wednesday

I don't know what's going in with Ryan's setup. It makes no sense to me that he goes from a 10" to dual 15"s and runs out of amp with 950 watts. A Bassis isn't going to help that situation

I like it when someone like Ilkka shares the workload, that helps keep my carpal tunnel symptoms in check...... :B

**---k---** · 08 March 2006, 16:21 Wednesday

Steve,
For some reason, I'm really slow these days understanding the finer details of LT. I'm not to the point yet where I fully understand the Bassis. I know it allows you to add boost and shift your Qtc around. Unibox tells me that with heavy fill, I'm already almost at Qtc=0.50, so that wouldn't help me. And, I'm not sure where the boost is getting added. That is why I wanted to see the full FR graph (and waterfall, if that were possible) with and without the Bassis. I was hoping that would explain it all. The graph you showed was impressive, seeing 12 db gain at 15hz. I just don't know what all else it is doing, and if it would do it for me. Thomas has said that PEW is enough for those of us with big enough boxes. So...

Besides, I'm not sure I'm at a point yet where I can tell you the differance between good bass and really good bass. I'm not sure I'm at the point where I can even tell flat FR from roller coaster FR. I can tell boomy sloppy bass, from puncy bass, but that is about it.

Listening to a Contrabass this past weekend was a very cool experance. It was amazing to feel my hair moving during the waves crashing in Blue Crush and War of the Worlds scene where the Aliens come out of the ground. That whole scene just had a real cool rumble to it, that I don't remember getting from my subs. During a scene from Open Range, where there is a gun shoot out, I remember thinking, "that is exactly what a 12ga shoot gun sounds like." Unfortuantly, there were about 10 people in the room, and all wanting something differnt, so it wasn't a real good oppertunity to play a scene over and over and really study the sound.

The other amazing thing to me, was it was loud, but not ear hurting loud. The entire system had been calibrated by Mark Seaton. It constisted of one Contrabass and B&W floorstanders. No room treatments or anything like that - only about 10 guys

. From what I understand, the demos were being played at a MV = 4. Mark really likes his bass, and the home owner had turned the sub level down 3db from where Mark set it, but Mark said that he bumped it back up 1 or 2db for the demo. So, we were listening at pretty high levels, but it sounded great. My hair was moving, my pants were slightly flapping, and you could feel it in your butt. But, I didn't walk away with my ears hurting or even really feeling like it was too loud.

I don't get this from my subs. My subs are loud. If something goes bang, there is plenty of bang there. They actually seem like they have more punch in kick drums and stuff like that than the Contra. But they don't have any of the real down low rumble. Never have I felt my hair move, like I did with the Contra. Also, I hate admitting this, becase it makes me feel stupid, but from time to time, my left ear will hurt, no ring, but feels like pressure being applied. I know, turn it down. But, I'm telling you when I use my SPL meter calibrate the system, it isn't that bad! And, I'm playing at lower levels that we were listening to this weekend.

I think Ilkka might have hit the nail on the head in my thread when he asked what the FR response looks like. I got such a big, wide null at my seat, that just shifts around going forward or backwards. I think I'm calibrating in a null, and getting a lot more SPL at certain frequencies than I realize. Even with using the BFD to correct it, if I lean forward or back, it is back. And, I do tend to move around in my seat a bit.

I need to investigate rearraging my room more. I do have a couple of other options. It is just so difficult, because the null is so bad in that one area of the room. You people with open floor plans, you may have to spend a lot more to get enough sub, but you don't have to deal with the crap FR like we do.

I'm almost to the point of paying Mark Seaton to come over help me. There is no doubt in my mind he would do a great job, and from what I hear is really reasonable. But, there is a pride issue here. I want to do it myself first.

Sorry to hijack. back to your bliss.

**---k---** · 08 March 2006, 16:26 Wednesday

Thomas,
It was a 12"!!! :B

**ThomasW** · 08 March 2006, 16:27 Wednesday

Thomas, It was a 12"!!! :B

Oops my bad ....

Ryan,

The Contra's are a vented alignment that is part of why they have higher low frequency output. You can't have a box that big. If you want a pair of 24" cubes you go with an additional investment in PR's and loose the magentic shielding where the PR's are placed

If the problem is the room (and I'm positive it is) unless Mark is a general contractor there's not much he can do.

===========================================

I ask Dennis H to type out a LT tutorial for a Dummies Guide to the Behringer DEQ2496 I'm writing. Here's Dennis' text

Linkwitz Transform
The Linkwitz transform is a type of equalizer that can be used to extend the bass response of a sealed woofer. You can read about the theory at the following links.

Active Filters

http://www.linkwitzlab.com/filters.htm#9

http://sound.westhost.com/linkwitz-transform.htm

wm8man.pdf

The PEQ function of the DEQ2496 can be used to duplicate the LT with three filters: two parametric band filters and one 12dB/octave shelving filter. You'll need to measure the response of the woofer as you apply the filters to get them tuned. The pic shows an example using the LT to covert a 40 Hz, Q=1 box into a 20 Hz, Q=0.5 box.

The first parametric filter is used to adjust the Q of the existing rolloff to 0.7 so the response is -3dB at Fb. If your box has a low Q, you'll need to boost a bit at Fb and if the Q is very high, you'll need to cut some.

The 12dB/octave shelving filter extends the bass. You could use a low shelving filter to boost the lows or a high shelving filter to cut the highs. Unfortunately, the lowest F you can set is 20 Hz so the low shelving may not get you as low as you would like. F is the lower of the two corner frequenies with the low shelving. Using the high shelving, F is the higher of the two frequencies, so just set that to Fb and cut the highs until the response looks like you want it to.

The second parametric filter is optional. After the shelving filter is applied, the Q at the new Fb will be 0.7. If you want to change that, you can use a parametric filter to boost or cut at that frequency and shape the rolloff.

If practice, you don't really need to worry too much about calculating Q and all that stuff. A perfect theoretical LT will work perfectly in an anechoic chamber but we use our subs in real rooms with nasty peaks and valleys, room gain, etc. We'll also be using the PEQ to correct for the room so we can forget the two parametric filters of the LT to start with. Just use the 12dB high shelving filter at your in-room F3 and cut the highs as much as you'd like to extend the bass. Once you have the extension you'd like, you can start using the band filters to flatten out the peaks and dips. That's really all there is to it.

Attached Files

wm8man.pdf (782.2 KB, 21 views)

**steve nn** · 08 March 2006, 16:44 Wednesday

A Bassis isn't going to help that situation

That's a certainty. So did he figure out that was the problem then? Last I heard was he (Ryan) was going to some kind of meet with Mark or something. I know he has the potential there for great bass and want to see him succeed.

I like it when someone like Ilkka shares the workload, that helps keep my carpal tunnel symptoms in check......

That's nice to see you say Thomas. I hope I didn't get to goo-goo in my post Thanking him, but he really is a wiz and has a keen understanding of programs as I'm sure you know. Anyway he sure dialed me in along with your help in building. You must get kind of self conscience thinking "ok somebody chime in here so I don't have to bare all the responsibility in helping twenty guys build a sub at the same time."..not to mention your carpal tunnel. I gather you enjoy it, but a little help is always appreciated I'm sure.

**---k---** · 08 March 2006, 16:59 Wednesday

Thomas,
Thanks for the link. I had read the Linkwitz site before. The second one was pretty good. Reading them again now, gives a little more perspective.

I'm not argueing with you. I know the Contra is a PR design, and therefore will have a lot more low end. I'm not expecting mine to be able to compete with a Contra. It was just a fun experance. I'm hoping that maybe if I move the subs to the corners, or something, I can make it better/similar.

But, I also got to hear another 15" sealed sub, (I don't think I can say much more about it at this point). It was really impressive also, but in a much smaller room. But, it was able to acheive the same hair moving, low rumbles that that Contra did. It wasn't quite in the same league, but was really impressive for the HT demo. I put in Bella Fleck, and I have to say that mine sounded a lot better here - like it had more punch. But, it hadn't be in the room more than 1/2 hour at this point, and no effort was made to find the best spot for it. After a little more listening, it got moved and the equalizer adjusted. I wasn't able to seriously listen to it after that.

Maybe it was just the eq that was giving it the low end, or maybe it was the room. I don't know. I need to investigate more. Finding time where I can play big bass for extending periods of time in my house is difficult. And I'm finding that I have just have so little in the way of referance points.

And, just for the record, I'm not unhappy; just in search of best I can do.

Edit:
Steve
As far as the subs making funny sounds, Mark is convinced that it is the amp clipping. I didn't really get to corner him for very long. He was the "cool guy" that everyone was pushing and shoving to talk to.

Mark I think has bigger/better tastes in amps than the rest of us. He just basically asked me what I expected from a $200 amp. He says that he has no problem clipping Crown XLS or QSC RMX series amps. I'm hoping that if I move the subs around, turn it down a little, get them calibrated at a reasonable level; then I probably won't have a problem. In the future though, I think to be safe I would recommend the Behringer that most seem to have success with or better.

**ThomasW** · 08 March 2006, 17:07 Wednesday

It's fine by me when others share the workload. For years Jon and I have 'pushed' the content for this forum. Now that others with knowledge are investing their time the forum will just get better.... :T

Mark is convinced that it is the amp clipping

It sounds like that from your description. I think the problem is the placement. I doubt that a more powerful amp is going to do very much

**Ilkka** · 08 March 2006, 17:07 Wednesday

Originally posted by steve nn

Ilkka, Ilkka..Ilkka! I just don't know what to say? I just skimmed through LOTR and not a hint of harshness. The bass was absolutely beautiful. Talk about impact! In the elephant scene when the footsteps resonate..I would expect to have to eq the top end out, but it came across very nice not to mention the low FR impact. I felt it was good before, but room for improvement..well you just put me forward to a level that I don't think I've ever experienced before??.. Maybe the dual Ultras? With out tweaking from your suggested settings (4dB on the boost) and no FBQ/BFD, the bass presentation was absolutely stellar.

This sound really good! I'm very excited how the settings turned out. Knowing how many subs you've had and heard, I think your comment is a big compliment for everyone who have helped you with your subs. Of course not forgetting Soundsplinter drivers.

So you have now 4 dB boost, right? It is not much, but if it sounds good, I'm fine with it. Of course you could try something like 12 dB, but I think it would became a little bit too bottom heavy. Of course it puts more load on the amps too.

Might you be able to tell me why the SQ was a little off with just the amp or FBQ and amp? It was good don't get me wrong and of course needed a little taming, but there was a little harshness in some of the presentation that I wouldn't of expected. I'll be interested in measuring the response and seeing what we're looking at. Anyway!.. I now am a firm advocate of the BASSIS and the importance of setting it up correctly, not to mention the FBQ for that matter. Yes still much to listen to and most likely a little gain in tweaking, but I feel totally confident I'm on solid ground now. :T :nos:

I'm not sure about the harshness, but one thing is sure, the settings on the Bassis weren't correct. It can certainly cause some weird things, but if they were also present without it...?

I would be interested to see the frequency response too. In the seats of course. You could also test if FBQ is causing any degrade in SQ? Just put it online, but don't do any corrections. I think at least Craig and Patrick (avaholic) have commented that they could hear the old BFD with their Maestros. FBQ should have better circuits, but who knows?

**ThomasW** · 08 March 2006, 17:12 Wednesday

I think at least Craig and Patrick (avaholic) have commented that they could hear the old BFD with their Maestros. FBQ should have better circuits, but who knows?

I've had the DSP1100P, DSP1124P, FBQ2496, and the Symetrix 551 all hooked to my big IB, and there was no audible difference.

Maybe I'm just deaf ... :B

Edit: when doing a comparison using the woofer section of my Arvo 3-ways (XO 175Hz-215Hz) the FBQ2496 was smoother than the DSP1124.

Dual RL-p15 D2 driver DIY..

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