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Message started by mrchet on 10/02/05 at 07:53:43

Title: What did I do wrong, DB10 sounds bad???
Post by mrchet on 10/02/05 at 07:53:43

I built me a DB10 with a Resonant Engineering 10SE in it (dual voice coil powered by a US Amps 1000D amp). †I was expecting to be blown away from reading this site's info. †It was the worst sounding box I've ever heard. >:( †I started reading this forum and found out some people where covering up the port with the insert. †I had only gone down to the top of the port. †So I kept sliding it down until in now covers over half the port. †It sounds better but I gave up. ::) †I played with the cross over points and dropped it from 150 Hz down to 80 and that helped a lot. †It was really sounding bad in the upper bass, kind of a hollow sound before that. †The sealed box I replaced, with this same woofer played a lot deeper but it wasn't as punchy. †Basically the box doesn't play deep, has to have the cross over point dropped, and when I turn it up the woofer sounds like it's really working hard trying to put out the sound. †I'd love to get some of my rumble back. †I could probably live with it now if it played deep. †
At this point I'm wondering if it doesnít like the woofer, or do I need to do something else?
I had a cabinet shop cut me the wood for a DB12 several years ago. †I never put it together because when I put a square on it I noticed that it was off a little. †Iím now thinking about maybe seeing if I can clean up the shape and put it together to test it with some JL 12W1ís that Iíve had for 10 years and never took out of their box to put in anything. †Who knows, but Iíve also thought about just buying the box and speaker off this site to see if that made a difference. :'(
At this point Iíll take any suggestions since Iím bumming about the sound. :(
Thanks,

CHET

Title: Re: What did I do wrong, DB10 sounds bad???
Post by Adrian D. on 10/02/05 at 12:43:44

Hey chet. you said you read a bit on the forum. did you ever think about air leaks between the baffle and the outer box ? because i also had those and for that reason i didn't have too much of a deep extension and i got a weird mooing noise as a bonus. try to seal it up befor putting too much power into it. my ultra-cheap woofer managed to move the baffle at high volumes during tuning. i was also veeery dissapointed, but after a few hours of listening, i began to sound better.
i guess that by lowering the baffle, you tune it lower. (i have mine at the top part of the port and i get response down to 37 hz - the woofer's freq range starts from 35 hz).
is the woofer brand-new ? if so, it needs some time to break in. do it as on the site, tune at low volumes.
don't abandon it because it's a great design (even with my cheapie it sounds really nice).

Title: Re: What did I do wrong, DB10 sounds bad???
Post by mrchet on 10/03/05 at 02:19:33

The baffle is so tight in the box that I have to beat it with a hammer end to move it down. †Even while tuning it I hooked up a 12" Pioneer that I had and it played a lot deeper than this box, although it isnít as efficient as the DB10. †I didn't round off the ports though, but that should only affect port noise and not low frequency. †I had thought of sealing the box around the baffle but I'm waiting to do so until I decide that it's the best I can do and then I'll seal it. †I didn't think that I should have had to worry about that at low volume during tuning.
I was wondering if it was the woofer, which was broken in with the previous box with several hundred hours. †Then I read in the forums of some other people that were using high end woofers and loved them. † So I passed on that idea
I'm still scratching my head wondering what to do. †At this point Iím ready to bust up the box to get the woofer back out and just put it back in a 1.6 cubic foot sealed box with another one and live with it.

Title: Re: What did I do wrong, DB10 sounds bad???
Post by Hotsauce on 10/03/05 at 02:26:47

Do you have the port facing the back of the car?  That helps immensly.

John C.


Title: Re: What did I do wrong, DB10 sounds bad???
Post by mrchet on 10/03/05 at 02:49:45

I did face the port to the back but it sounds better pointed up. †I think the reason is that it doesn't have enough room to breathe that way. †There's only about 3" between the box and the tailgate in my Scion XB.
Even at low volumes while tuning it I'd switch the speaker leads over to the old woofer and you could feel the bass vibrating the car. †With the DB10 it doesn't do that. :'(

Title: Re: What did I do wrong, DB10 sounds bad???
Post by gexter on 10/03/05 at 06:04:44

I am perplexed!
sounds like you did everything right.
It just may not simply play as deep as your other box. Or the deepness ( is that a word) may not be the sub itself but the box's reaction.
The DB is pretty precise and 0 resonance like all steves stuff.
I am not as big of fan of the DB as the WO but It can't be that bad.
some drivers do sound better than others in the DB. I put a driver in the DB and then swapped it into an modified Imperial and the differance was amazing.

Double check for air leaks in the sealed chamber.
Keep trying locations
Try reversing the polarity to change the phase
Too bad you sealed it up you could try some dacron.

If you carfully remove the bottom where the half moon is you may be able to salvage everything without busting the box up.
You might have to shave a hair off the base of the box if you used glue and just cut a new bottom piece if it is wreaked.

best of luck

gex

Title: Re: What did I do wrong, DB10 sounds bad???
Post by DirtDawg on 10/03/05 at 08:26:09

Tune it lower. Get the hammer out to move it if you have to, but if you're still getting too much mid bass you may just need to go lower, cab tuning and XO.

Title: Re: What did I do wrong, DB10 sounds bad???
Post by rock4016 on 10/03/05 at 14:50:20

Have you noticed a difference in the sound with the front windows down about 4" ? †I've noticed with my deathbox some of the smaller cars don't have enough interior room for it to "breathe"

Also have you tried installing the sub so the magnet resides in the ported side?
Also you can add polyfill to the sealed side.
I would use a steep slope crossover 18-24DB at less than 90hz.

Title: Re: What did I do wrong, DB10 sounds bad???
Post by 60ndown on 10/03/05 at 15:07:45


mrchet wrote on 10/02/05 at 07:53:43:
I built me a DB10 with a Resonant Engineering 10SE in it (dual voice coil powered by a US Amps 1000D amp). †I was expecting to be blown away from reading this site's info. †It was the worst sounding box I've ever heard. >:( †I started reading this forum and found out some people where covering up the port with the insert. †I had only gone down to the top of the port. †So I kept sliding it down until in now covers over half the port. †It sounds better but I gave up. ::) †I played with the cross over points and dropped it from 150 Hz down to 80 and that helped a lot. †It was really sounding bad in the upper bass, kind of a hollow sound before that. †The sealed box I replaced, with this same woofer played a lot deeper but it wasn't as punchy. †Basically the box doesn't play deep, has to have the cross over point dropped, and when I turn it up the woofer sounds like it's really working hard trying to put out the sound. †I'd love to get some of my rumble back. †I could probably live with it now if it played deep. †
At this point I'm wondering if it doesnít like the woofer, or do I need to do something else?
I had a cabinet shop cut me the wood for a DB12 several years ago. †I never put it together because when I put a square on it I noticed that it was off a little. †Iím now thinking about maybe seeing if I can clean up the shape and put it together to test it with some JL 12W1ís that Iíve had for 10 years and never took out of their box to put in anything. †Who knows, but Iíve also thought about just buying the box and speaker off this site to see if that made a difference. :'(
At this point Iíll take any suggestions since Iím bumming about the sound. :(
Thanks,

CHET



try moveing the inner baffle down so it is about 1 or 2 inches from the bottom.so it covers almost all the port.

Title: Re: What did I do wrong, DB10 sounds bad???
Post by J_Rock on 10/03/05 at 19:26:48

Definatively, you must move the baffle, so break that bitch free!

and then after moving that around for days playing sweeps or low tones, you should get where you wanna be.  Try swapping the magnet into the ported section like above stated, that will increase the volume and lower tuning. Also try polyfill if you can tune it low enough, in the port and the sealed chamber.  

And if that doesn't work, where do you live?  Because its you air there, it can't support the high sound pressure levels so the lower frequencies clip. (Thats the only other conclusion.)

Title: Re: What did I do wrong, DB10 sounds bad???
Post by 60ndown on 10/05/05 at 15:45:46

are you sure you have the voice coils connected correctly? i have heard of some dvc subs leaving the factory with +ve and -tve terminals maked incorrectly?

Title: Re: What did I do wrong, DB10 sounds bad???
Post by gexter on 10/05/05 at 20:18:53

Hmm Never seen that yet. that would be a pain!!
Wheres the quality control guys when you need them!!

Use a small battery for a polarity test just in case you don't know it already. It only takes a brief touch to see it the polarity is correct.

Gex

Title: Re: What did I do wrong, DB10 sounds bad???
Post by mrchet on 10/06/05 at 01:47:02

OK here's the latest. †
I played with it a little more. †How much can I move the baffle towards the bottom before it starts to cut off the air flow and ruin the sound. †Here where I'm at now. †Do I need to go more? †What's the most anyone has gone? †The speakers only need .6cft of air space in a sealed box. †So when I started tuning it I had the speaker sitting in the middle of the box.
http://www.computerwrestlers.com/Box_pix/IMG_2399.JPG
I changed the box and put it on it's side and pointed the port to the back. †Instead of having the port on the bottom. †It helped, it hits pretty good now but still doesn't play as deep as I want. †
http://www.computerwrestlers.com/Box_pix/IMG_2396.JPG
I bought some poly fill but I haven't had a chance to put it in yet. †
I played it with the windows open and closed and there is a slight difference with them open. †It seemed to help very little. †
As far as I know the voice coils are correct because I ran this driver in a sealed cabinet before I built this one. †I din't change the wiring for the second voice coil. †That's why I know it capable of playing deeper. †In the sealed box it used to rumble and vibrate but it didn't hit hard. †Now it hits hard but won't rumble.
I'm OK with the sound right now and could live with it but I want more!

Title: Re: What did I do wrong, DB10 sounds bad???
Post by 60ndown on 10/06/05 at 04:36:51


mrchet wrote on 10/06/05 at 01:47:02:
I'm OK with the sound right now and could live with it but I want more!


what power in wrms does your amp supply? what is your ssf set to?

Title: Re: What did I do wrong, DB10 sounds bad???
Post by 60ndown on 10/06/05 at 04:40:34

also it looks like you inner baffle is at an angle?? see if you can make it straight and then seal it completely, where it is.

Title: Re: What did I do wrong, DB10 sounds bad???
Post by gexter on 10/06/05 at 05:58:46

It also seem angled to me.
In my humble opinion you would only have about .5 of an inch if you were going to go lower.
I find that the lower I go the lower the output, as in Hz and volume, But not always the case with others.
I would smooth out that half moon just even if it is for appearance only.

and I take it that it still is not working for you.

Gex

Title: Re: What did I do wrong, DB10 sounds bad???
Post by mrchet on 10/07/05 at 19:09:38

I'm running a US AMPS 1000 watt digital amp. †It's the one on the bottom in the pictures. †The one on top is their 300T tube amps that puts out 150 watts per channel to my MB Quart mids and highs up front.
I checked the baffle out because the picture really makes it look off, and it was by almost 1/4". †I didn't notice it before. ::) †
I beat the baffle down more and put some polyfill in it. †It plays deeper and the hollow upper bass sound is gone. †I decided that it was good enough and that I'd go ahead and seal it. †Just before I did that I thought what the heck and beat the baffle down some more, then I sealed it up. †I'm letting it dry now but I think I'm going to be happy with it now. †It was sounding decent so I'm going to live with it this way for a while. †
I think that the biggest problem was that I didn't think I could cover the port with the baffle without killing the sound.
Here's some of the latest pics.
http://www.computerwrestlers.com/Box_pix/Sub%20001.jpg
http://www.computerwrestlers.com/Box_pix/Sub%20007.jpg
http://www.computerwrestlers.com/Box_pix/Sub%20012.jpg
http://www.computerwrestlers.com/Box_pix/Sub%20013.jpg

Title: Re: What did I do wrong, DB10 sounds bad???
Post by 60ndown on 10/08/05 at 15:23:19

pics no worky?

Title: Re: What did I do wrong, DB10 sounds bad???
Post by mrchet on 10/09/05 at 02:17:08

Sorry about pics not working right. †The first two I forgot to put in a 0, but the last two worked. †They are all working now. †I guess I should have checked the links when I posted it. †I was in a hurry.
The sound now is good. †I'm happy with it. †I can't tune the crossover above 80hz or it starts to get that nasally sound again. †But now I'm feeling the bass and hearing it vibrate things like the CD cases that are in the door pockets. †Much better now, and I'm enjoying it. †Although I want more, so I'm still going to do my original idea and put some subs under the front seats. †It's just a bigger project than I have time for right now. †I only built the DB as an experiment to get more bass than I had . †Which now that it's tuned better is happening. †You were right about it playing lower but not as loud. †My biggest problem is that I haul a lot of stuff and really didn't want anything back there. †At least with this box I can stand it up when I need to and it doesn't take up as much room that way. †I would also like to build a box to put in it that really jams for those times when I want to get crazy! †Maybe a WO would be a good project and then I could store it in the living room when I'm not using it in the car.

Title: Re: What did I do wrong, DB10 sounds bad???
Post by 60ndown on 10/09/05 at 15:12:04

the db will jam, just need to set it up right, it hits hard and low. but as will all 'home brew'projects, there is room for error?

Title: Re: What did I do wrong, DB10 sounds bad???
Post by Erix on 10/10/05 at 10:10:32

Looks like your half moon port is not correct. When I look at your pictures it's not wide enough. This cranks up the tuning frequency...

Title: Re: What did I do wrong, DB10 sounds bad???
Post by gexter on 10/10/05 at 13:56:29

mrchet- Erix may be right, sometimes it is hard to tell from pictures.
When you built it and the baffle sat crooked that would cause a world of trouble and air would leak past the baffle.
One of your picks show the the top was not sealed before. that would have caused the same problem.
It looks like it is sealed up now and it was not before, which is making up for some of the build errors ( I have done the same thing even when I was not in a hurry) I am more of a mechanic and computer person than a woodworker. Or was anyway. I always enjoyed building speakers.

I think you should still check for leaks around the top and sides to be sure.

With all the differant characteristics of drivers ( even good ones) some will not play as well as others in specific enclosures.

The DB compensates only partly ( thats an opinion)

good luck

Gex




Title: Re: What did I do wrong, DB10 sounds bad???
Post by 60ndown on 10/10/05 at 15:29:42

erix has a good point-your half moon does look a little small? did you cut it to the exact measurement?

Title: Re: What did I do wrong, DB10 sounds bad???
Post by 60ndown on 10/10/05 at 15:32:19

it also looks like there is polyfill inside your sub??????????? if you look thru the magnet towards the cone it looks like polyfill in there?-cant be good!

Title: Re: What did I do wrong, DB10 sounds bad???
Post by DirtDawg on 10/10/05 at 16:06:06

Good catch 60!

I try to keep my nose out of here since I don't have a DB, but stuffing in the motor is always bad news. CAREFULLY remove it and make sure you get it all. Another point ......... the port doesn't look the same as other pics I've seen. It definitely looks too small. :'(

Title: Re: What did I do wrong, DB10 sounds bad???
Post by Adrian D. on 10/11/05 at 13:36:58

yup, i agree about the half-moon. mine definetly looks bigger : http://img412.imageshack.us/img412/4514/100022xi.jpg
sorry about the nasty pic. it's not digital
the half-moon port is not a half-circle. i guess chet cut it like a half-circle, using the port height as radius, which means that the width is double the height (it should be about triple the height)
i found a pic of the sub without polyfill in the motor..... http://www.computerwrestlers.com/Box_pix/Sub%20003.jpg

Title: Re: What did I do wrong, DB10 sounds bad???
Post by HB Bass on 10/12/05 at 16:59:06

You guys are probably onto the root causes of the poor performance.  The port looks like it was cut with the centerpoint on the bottom rather than "x" dimension below.  

Mrchet check the 2.6" dimension and see if it is not 3.5" instead.  If this is wrong you should be able to set your baffle about 2.6" from the bottom and then use a Dremel or jigsaw to carefully "widen" the port.  This I think should help with the low end freq while moving the baffle back up to a more "normal" position should bring back the "punch" you are now missing.  

:'( Now I tell you after you've already got the baffle sealed!

One other thing I did was use some weatherstripping for a gasget on the top.  Even with a very snug fit mine still leaked without a gasket.  Any leakage will cause cancellation and distortion.

Good Luck

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