HELP! Completed sub is bad!

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OK.
I built my sub.
It is a ported 118L box. port is 4" and 17" long (uncut flared port kit) so it should be tuned to approx. 20.5 hz.
Driver is a SHiva Mk IV powered by a PE250w amp.

It is bad! My yamaha 8" sealed sub plays louder.

It sounds really distorted like it is blown at low levels. If I can get it to go louder it sounds like it is bottoming out hard but what appears to be very little travel. Nothing is hitting the back of the woofer.
I have tested the amp by powering an old center speaker I have. It seemed to go ok. I had to turn the crossover all the up of course. I tested the driver by hooking up to my main speaker wire. SOunded bad cuz it was not in a box but seemed to function fine.

I have played w/ the phase, gain level, and the crossover. I have turned the crossover all the way down to the 40hzs and the gain to about 1/3 and still it sounds bad.

My receiver is couple yrs old. Has a sub pre-out (rca) but no menu to for settings.

The box is stout. No leaks. The bracing is good unless I have to much. You can see pix here in this thread

http://www.diyaudio.com/forums/showthread.php?s=&threadid=28269

or here at this website.

http://dodgetrucks.org/cgi-bin/index.pl?cat=500&thumb=1&stype=2&si=pne123

it is a 14x12 room centered in the middle of the 12' wall.

any ideas? please help. my wife is really starting to look at me funny. I really thought I had this nailed.

thank you in advance.
 
jjacks4x
wow thanks. I am in south san jose. blossom hill and 85 area.

If I do not get this figured out in a couple of days, I just might take you up on your offer.

Has for wiring, yes dvc and yes they are right. black to neg. red to pos. ...neg to neg and pos to pos. the wires cross going from on voice coil to the next.
 
The speaker is dvc @ 8ohms each so I am at 4ohms in parallel.
The amp is rated at 250w at 4ohms and used alot in the same configuration. unless i just got a bad one.

I tried just one vc and it still sounded bad. I forgot to check the other one alone. I might have just one vc bad....
 
I have a first gen Shiva, along with a PE 12DVC, and two of the PE amps. I have the Shiva in a 12x16 room with two open doorways and lots of glass. It produces plenty of bass for HT and too much for some music. I currently have the port plugged, for a low Q sealed. It sounds like something is wrong with yours, or your set-up.

Here are some things you may want to check:

Is your PE amp one with boost or without? For ported, you should have no boost. It is a couple of resistor change, on one of the boards.

How long is the port, not counting the flared ends? I haven't looked at port calcs for this, in a long time, but I get the impression yours might be too short to get 20.5Hz tuning. Are you able to do frequency sweeps? If so, you should get no cone movement at 20.5Hz, if tuned there.

How does it sound with the port plugged?

How hot is your amp getting? Can you still hold your hand on the heat sink?

Also, try other room locations, including the nearest corners.

I assume the new Shivas are still stamped frames. Make sure they are drawn down evenly and the edge is not hitting on a recess, and the frame didn't get twisted.

Some early Shivas had an issue with lead slap on the back of the cone. I doubt that is an issue with yours, but I added some foam at the leads.

I imagine that the Yamaha 8" over produced in the upper mid-bass. Do you have a SPL meter and test tones, to varify? What is lowest freq your mains put out?


BTW, very nice cabinet work.
 
the amp is w/o boost.

I ran my front main speaker wire thru the port and to the speaker. I still have the same problem. It played better do to the higher frequency (i am guessing) but still made the bad metalic noise.

The port is 17" w/o flares

sounds the same w/ the plug port.

did not specifically feel amp but never noticed any heat. not on very long to notice it was bad wrong

i have not moved it around trying to get it to sound better. it does not play at all so....did not see any reason to lub it around the room.

still stamped.

Is it possible that my cut out and recess cutout are to tight and this would cause the problem? The flange is very close (1/32-1/64) to the recess flange. The 11" cutout is also tight.

I am close to my bracing but not touching. The magnet is about 1/2 from the center brace. The braces from center to exterior walls is very close at the opening. If it was touching would it make bad noises? should I get my saw out and cut those back?

thank you
 
Ran a simulation:
The design seem like a nearly perfect butterworth with ~20Hz lower cutoff. Max output level should be 110 dB @1m, half space down to 25 Hz. There *should* be plenty of umph in this box...

As the others have already said, checking the polarity of the coils would be number one. Do you have a computer connected to it? If so, you could run some sine sweeps to determine that the vent is really tuned to ~20 Hz. If you connect series resistance of ~100 ohms and measure the voltage over the speaker you should have a voltage minimum at ~20Hz. This corresponds to the vent tuning frequency. You will also find a second minimum at about 100 Hz in this design.

You can find a tone generator program at:
http://www.speech.kth.se/music/downloads/smptool/

I did not see the vent tube in the previous posts, but I understand the diameter was 4" and that it was 17" long? That makes sense and should give a 20Hz port resonance.

If you hear *distorsion*, and the coils have the right polarity, there is a chance that the driver is broken. Try to move the cone carefully by hand. If you feel a scratching sensation in the hand, there might be a transportation damage. This has happened to me once. Also, sine sweeps can help to hear broken voice coils, if the quality of the tone abruptly changes during the sweep, and everything else is tightly glued etc, this would indicate a broken driver.

HTH
/Svante
 
Ok, I think I have bad speaker.

after running it from my receiver it still made the same noise. sounds like a rattling trunk lid on a ricer.

I removed it from the box, turned down my plate amp. still made the noise at low levels. both voice coils made the noise running seperately and together. The cone is only moving a couple MM

I was suspending it w/ my fingers so it was not vibrating against anything.

I guess I will have to return it or am I just completely missing something?
 
but still made the bad metalic noise.

No, it should not make a metalic noise. But if I understood your prior posts, you did run it outside the cabinet with no metalic noise, correct? If it made the noise then, its probably a bad driver, and need to place a call to Adire.


Is it possible that my cut out and recess cutout are to tight and this would cause the problem? The flange is very close (1/32-1/64) to the recess flange. The 11" cutout is also tight.

If the frame is twisted, it could cause the voice coil to rub. I would try to give it some more clearance.

I am close to my bracing but not touching. The magnet is about 1/2 from the center brace. The braces from center to exterior walls is very close at the opening. If it was touching would it make bad noises? should I get my saw out and cut those back?

If they are touching the frame or the driver is moving under excursion and hitting, you will need more clearance. Can you temp mount the driver upside down, magnet on the outside? That should eliminate any chance of hitting, plus provide a view, that could show other issues.

unibox and winisd pro both say 17" port.

Yep, I have used both, but always varify tuning. Impedance sweeps are nice in that they also provide other info. May see other peaks, that might indicate a leak, etc. Freq sweeps and no cone movement @ 20HZ will tell you if its tuned correctly.
 
From your description of the sounds your driver is making, I think the voice coil is rubbing in the gap. This can be caused by manufacturing defects, shipping damage, overpowering the driver, and warping the frame during installation. If your driver has been doing this since day 1, you should contact Adire and get a replacement. Also, when you get your replacement, make sure that the driver opening in your cabinet is big enough to not warp the basket when you install it. A warped basket can cause the voice coil to move slightly out of center, causing rubbing and the horrible noise you are describing. I hope this helps.

Cheers,
Zach
 
thank you.

yes it made the noise out of the cabinet also.

I check and it not hitting anything at all inside the cabinet. I could verify thru the amp hole.

I got my calipers out and measured the basket and my hole and it fits just fine.

This was the very first attempt to use the driver. I have only had a few days sitting in the box while I built the cabinet.

Must have been bad from factory or damaged in shipment.

I was supprised at the lack of packing material. Just the drive upside down in a cardboard box w/ epanda-form in a plastic bag holding it from sliding.
 
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