pearlfection-the ultimate vmps large sub cabinet-(pic)

rosconey · « **on:** 16 Jun 2005, 08:31 pm »

today i started my 3rd homebrew cabinet-this one if for my vmps large sub drivers-

i have been thinging about away to make a cabinet that uses the least amount of floor space-

so today i stated it,a corner mounted tallboy style cabinet with the pr front mounted(not sure how well it will work ) but for 40$ worth of mdf what the heck-
dont ask how i came up with my measurments because i dont have any idea-like allways i just start cutting and let everything come together-

58 inches tall,17.5" sides with 4" wings-face is 18"-from the top it looks like a diamond

15" driver at the top with the 12" under it,the passive is mounted near the floor-3" up from the bottom-

i still have a few braces to cut and final glue and nail-its about 80% done or better-

i plan on painting it the same color as the walls in the room

will keep you guys posted

warnerwh · « **Reply #1 on:** 16 Jun 2005, 08:49 pm »

One thing you have to remember and is very important is to keep the same cabinet volume. Good luck. I think it's a good idea. I wish my sub was a tallboy but I'm not going to butcher it. You don't want to see my woodworking skills.

rosconey · « **Reply #2 on:** 16 Jun 2005, 10:01 pm »

i took a guestamet on the volume-i think its oversize alittle bit but i can put a filler at the bottom 3" and add a 45% piece against the back corner-

math was never a subject i paid attention to-
i started with the standard large cabinet and measured across from the top right to the bottom left ,wasnt sure if it was deep enough for the drivers so i added the 4" wings and took some hight off to try and keep the volume close-

figure i can add stuff to decrease volume

JoshK · « **Reply #3 on:** 16 Jun 2005, 11:10 pm »

pictures!

rosconey · « **Reply #4 on:** 17 Jun 2005, 01:41 am »

http://www.audiocircle.com/index.php?action=gallery;area=browse;album=505

rosconey · « **Reply #5 on:** 17 Jun 2005, 03:48 pm »

as klaus would say-
he he he

wired up and running-
best part it takes up almost no floor space and is still big enough to give that great vmps bass-no standing waves because of cabinet shape -also rock solid- and one corner is taken out of the room dynamics-15" powered woofer is 48" on the center plug off the floor and down from the ceiling
-some of thgese things jhave to effect the sound-just dont know yet if its good or bad-
still have some fine tuning and most of the finish work left-will tune this weekend but who knows when i will get the finish work done

rosconey · « **Reply #6 on:** 18 Jun 2005, 04:02 pm »

well this am i bought 10$ worth of carpet and covered it-added some 1.5" styrofoam insulation in the side wings and a bunch more fiberglass insulation-sealed the drivers with foam tape-
so now its air tight with a little less internal volume

all i can say is

total cost-
40$ mdf
10$ carpet and glue
20$ binding posts

will have some pics by the end of the weekend

thinking about adding some tube grill covers that parts express has

W.C. · « **Reply #7 on:** 18 Jun 2005, 07:13 pm »

Wnat are you using for a crossover???

ekovalsky · « **Reply #8 on:** 18 Jun 2005, 09:57 pm »

rosconey,

Corner subs will maximize output and extension. They also give the best time coherence since there is essentially no delay in reflections from the adjacent walls, unlike typical sub arrangements.

Unfortunately they also create a worst case situation for room nodes. You may have 20dB or even higher peaks at certain frequencies. This can give the impression of incredibly powerful bass which is most impressive to non-audiophiles

but alas it is far from accurate and also drowns out bass information at other frequencies away from the nodes.

This is the perfect situation for room correction -- maximize sub output & extension with ideal time domain behavior by using corner placement, and tame the bass nodes with digital EQ. Near full range main channels supplemented with corner subs is the hallmark of an all out TacT system.

I'll also add that having front-facing (or maybe side firing) passive radiators or vents is the best way to go. None of the bottom or rear firing systems have sounded quite right to me.

Here are a few pics of the baby TacT corner subs, the W210. They may give some ideas on building a corner cabinet:

This is a construction diagram for the bigger W410 corner subwoofer. These retail for about $3690 each. If the link doesn't work and you want it shoot me a PM with your email address and I'll send it.

rosconey · « **Reply #9 on:** 18 Jun 2005, 10:23 pm »

i use fmods from partsexpress-70 low pass

http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=266-252

ekovalsky-
that is a little tyke you have there-mine is its much bigger not as polished brother

i have much smaller sides(wings) on mine-i wanted it as tight as possable in the corner
i also run my mains full range-

also had a few friends who know my system by for a listen-
bolth thought it was a major improvement,one guy has always said my bass was directional to him-not anymore

rosconey · « **Reply #10 on:** 19 Jun 2005, 08:22 am »

more pics
http://www.audiocircle.com/index.php?action=gallery;area=browse;album=505

ctviggen · « **Reply #11 on:** 19 Jun 2005, 09:46 pm »

Can room correction deal with 20 dB peaks? (I assume you mean above some "middle level".)

zybar · « **Reply #12 on:** 19 Jun 2005, 10:16 pm »

Quote from: ctviggen

Can room correction deal with 20 dB peaks? (I assume you mean above some "middle level".)

The TacT preamp can.

George

warnerwh · « **Reply #13 on:** 20 Jun 2005, 02:52 am »

Bob: I have four bass traps in my 12x17 room. My speakers are RM 40's and a Vmps sub. I get peaks of 7-8 db still. I should add I run the 40's rull range. Without the treatment it's twice as bad or more. The Rdes unit is the next best thing since the Tact and Deqx stuff. Being a dealer for the Rdes units now it's hard for me to recommend things without people thinking I'm trying to sell something but it's my honest opinion that more people need them than realize it. If you have walls you have nasty peaks and dips in the bass range muddying up the bass and midrange. George and Eric are right and a Tact or something like it is in my future but I have really good sound now and will worry about it later when I have more money. A Tact is the only component I think that can make a significant improvement in my system at this time. At least it's the only significant improvement I could afford short of a custom room by Rives.

ekovalsky · « **Reply #14 on:** 20 Jun 2005, 04:28 am »

The TacT can easily deal with peaks of any amplitude. Dips are a bigger problem and cannot be directly corrected. However, with careful placement of the speakers and listening position (with the TacT showing immediate results) they can be minimized.

I'm not familiar with the RDES but if it offers 4 bands of variable parametric EQ it should be able to tackle 90% of bass problems in most rooms. I would think that anyone's setup could benefit from such a unit -- any sonic degradation introduced by the ADC/DAC stages would probably be more than offset by the restoration of natural in-room bass response.

I've talked with a few audiophiles who have all-out Rives installations and they still have bass irregularities. They are inevitable in any enclosed listening environment!

ss397 · « **Reply #15 on:** 20 Jun 2005, 02:57 pm »

this is getting off topic but i was wondering why you guys chose the tact preamp over the DEQX. i have been thinking about moving into the room correction area and am trying to get a better understanding of it.

rosconey · « **Reply #16 on:** 22 Jun 2005, 02:57 pm »

ok some more thoughts

1-system appears louder at the same volume setting,i have no explanation
2-no way you can say my bass is directional-
3-massive improvement in system clarity,dynamics-i was very very happy before the new sub cabinet but now its just plain sick-
4-the sub now blends with the mains like peanut butter and jelly

over the weekend a few friends who have heard my system quite a bit all said they couldnt believe all i did was change the cabinet-they noticed the sound differance without me saying a thing

ctviggen · « **Reply #17 on:** 22 Jun 2005, 03:39 pm »

The TACT actually determines a complex filter that will create the desired frequency response from input. The DEQX has seven parametric equalizers. From a technical standpoint, the TACT is better and will likely take less time to get right. However, the TACT only provides room correction and not speaker correction, whereas the DEQX has both.

20 dB over some base level? I (a) find it hard to believe that such a peak would even exist (certainly the room modes I'm experiencing don't come anywhere near that -- remember, 20 dB is a 100 times increase in SPL over the base level), (b) would like to see an actual example of such a peak and TACT's correction of the peak, and (c) wonder what kind of processing the TACT is doing to create/modify a filter able to lop off 20 dB while still joining the "endpoints" of the lopped off hump with the adjacent frequency ranges, with no discontinuities and while still providing correct phase response. If true, that's impressive.

I don't doubt that digital correction is the way to go. However, if you have a 20dB peak over a base level, you should seriously consider room treatments (and perhaps moving your sub) in addition to digital correction. Remember, digital correction does not stop mode "ringing", and a 20dB over a base level mode is probably going to have a horrendous RT60 time (the time it takes to go from some initial level to 60dB below that level). In fact, you may not be able to determine an RT60 time. Moreover, if you have multiple room modes that cause the 20dB over a base level peak, any time your system produces a frequency near that peak, you're going to be exciting those room modes and causing ringing. And that's something no amount of digital correction will fix.

zybar · « **Reply #18 on:** 22 Jun 2005, 10:07 pm »

Quote from: ctviggen

The TACT actually determines a complex filter that will create the desired frequency response from input. The DEQX has seven parametric equalizers. From a technical standpoint, the TACT is better and will likely take less time to get right. However, the TACT only provides room correction and not speaker correction, whereas the DEQX has both.

20 dB over some base level? I (a) find it hard to believe that such a peak would even exist (certainly the room modes I'm experiencing don't come anywhere near t ...

Even with my big room, proper placement, and lots of acoustic treatment I had differences of more than 20db within a 30Hz span with my VMPS speakers.

Ethan talks about much larger swings or differences on his website so I am not sure why you are skeptical of the claims.

With the TacT correcting the peaks, people couldn't localize the subs in my room and thought the sound was quite good.

I am not going to try and exlain it from a technical perspective, nor do I really care.

I just know what was heard (by myself and people who listened to the system).

George

warnerwh · « **Reply #19 on:** 23 Jun 2005, 04:19 am »

Bob: Have you taken any measurements in your room? If you have swings of more more than + or - 12db you're lucky. As George says peaks of 30db have been measured. Average, according to what I've read, is somewhere around the plus or minus 15db for an average room. Both rooms I've measured have been near this so anything a little higher or lower seems plausible. Bass is a bitch.