My old Dharman is down, any advice (1 Viewer)

[ShanonS]

Well, got the SD12 in last night. Looked it over, indeed only one set of leads. Cut the Shiva off, stripped the wires and screwed them into the very nice binding posts on the SD12. This thing is a monster. Much heavier than the Shiva. Unhooked everything and layed the box on it's back since the SD12 is so much heavier than the Shiva. No way to hold it up by the rim and screw it in. Put everything back together and plug it back in. Turn it on and it sounds exactly like the Shiva did before I took it out. Making the same popping/crackling sounds. I guess the driver wasn't blown after all. Now I've got to do a lot more experimenting to try and figure this out. I'm starting to wonder if all of the Audyssey EQ-ing is doing something very strange to my sub. It got worse after I turned the gain down on the sub and re-ran Audyssey. I thought I was just making the driver I thought was blown worse by playing around with it more. I guess I'll try disabling Audyssey when I get home and see what that does. I just can't imagine that this would cause the type of sounds I am hearing. The strange thing is, dish sounds fine, but DVD and X360 both have the same problems. Probably just because there isn't much on the .1 channel coming from TV programs. I thought this was going to be an easy fix.

 

[Robert_J]

Do you have your satellite set up to send Dolby Digital to your receiver? Find a good action movie to test with. Also try another receiver even it you have to take the sub to a friend's house. It could even be your amp going bad.

Nothing is ever an easy fix but they are learning experiences. That's why I have an extra 9 subwoofer amps and 25 subwoofer drivers just sitting around. I can always test something.

-Robert

 

[ShanonS]

I disabled the Audyssey Dynamic EQ and it immediately got rid of most of the noise I was hearing. I still have some of the same issues in the scene where I first noticed the problem. I even completely disabled the Audyssey EQ XT, but it's still there. At least I'm back where I started, or at least with an upgraded driver I now don't seem to need, but it is definitely a stockier sub. Now I need some time to play around with it and see if I can get rid of the continuing issue. I just don't understand why the dynamic EQ would cause this problem, and it bothers me that I won't be able to use this feature, but I'll work on it some more and see where I get, it's just been a busy weekend and haven't been able to touch it since last night.

 

[Robert_J]

I'm sorry I recommended a speaker that you may not need. But from your descriptions it was blown. Diagnosing audio issues over the internet is like diagnosing car problems. 'Ca-chunk, ca-chunk, ca-chunk' doesn't help the mechanic one bit.

I can't really help with Audyssey as I have no first hand experience with it.

If I were you I would still keep the CSS sub in the box. At least you won't have to worry about bottoming it out on some of these scenes.

-Robert

 

[ShanonS]

No, don't take that wrong. That wasn't directed to you at all, it was my mistake. I appreciate all your help. I was listening to it myself and it really made it sound like the sub was blown. It got worse as I played with it, and I interpreted that incorrectly as indicating that I was making the blown driver worse by continuing to play the scenes it was having problems with. I should have experimented more before just deciding it was the driver itself. You helped me find a good driver to replace it and verified that the one suggested would work. It's definitely a better built sub. You helped me rule that out as the issue. Like you said, it still could be an issue with the amp. I just need some more time to play around with it. It still seems fine when watching my Dish DVR. I even turned the dynamic EQ and dynamic volume control back on while watching Discovery with my son yesterday afternoon and watched a couple of things off of the DVR last night and had no issues at all. We weren't watching action movies, but we watched CSI with some heavy bass music and shootouts.

 

[ShanonS]

Well, I finally took some time and tried a couple of things tonight. I completely forgot that my mains have an LFE input. I know they have their own amp for the small dual bass drivers, but I had forgotten that they had a line level input. So, I turned off the Dharman and moved the Sub cable to one of the mains. Then I recalibrated my receiver using Audyssey. I didn't get any of the noise I was hearing from the Dharman. I even turned on the Dynamic EQ that made the Dharman almost constantly distort and it didn't have any trouble. Only time it had problems was with was the deepest bass, but getting up close to the speaker, I'm pretty sure it was just the port chuffing. I even moved the cable back over to the Dharman and turned the gain down some and dialed back the sub trim in the receiver and it was just crackle, crackle, thump. So, the latest experiment leads me to think it is the amp on the Dharman. If it was distortion from the receiver, or a problem with the sub cable, I would think it would have been evident with the other speaker. I even tried moving the power cord on the Dharman to a different outlet with nothing else plugged in. Is there anything else you think I should try?

I found someone selling a brand new O audio 500 watt BASH amp for a decent price. Would that be a suitable amp to replace the existing one? I've done some looking and I see where most people recommend that amp for sealed subs since it has the boost associated with the LPF, but since this box is tuned to 22 hz, I don't think the associated boost at the 20 hz setting would be too much of a problem. I don't know about the big boost it gives at the 16 hz setting. If that amp would be good, then the issue is whether or not it is a similar size to the current amp, since it is used to seal the back of the box on the Dharman.

 

[Robert_J]

The O-Audio amp is excellent as well as the other BASH amps available from Parts Express. The nice thing about the O is the adjustable SSF. The PE amps are adjustable but you have to de-solder and replace resistors to do it. Just turn a knob on the O.

If the hole is too large, add some MDF to fill in the hole to make it the proper size for the new amp. If the hole is too small, there are numerous different saws that can take care of that situtation.

-Robert

 

[ShanonS]

Well, haven't heard back from the guy with the O Audio, so I'm on to buying one out-right. PE has their 300 BASH on sale right now for $125 free shipping, so, is there any reason not to go with that amp. I understand the O Audio has some more options, but for another $50, is it really worth it? I thought the Darman was plenty loud before for my listening style, and I don't think I ever had the gain at even half before. Is there any reason to go with a 500w over just a 300? The original amp was just a 280w according to the Dharman specs. Is there anything I'm missing?

If I go with the PE, do I need to modify it before I install it, or should I install it first and do some testing with it? I couldn't tell from the PE BASH 300 specs where the LPF is set out of the box or if it had any boost without changing out resistors. The Dharman specs say the amp had a custom EQ already, but I can't find anything that says what it was. The specs you gave me on the subs were without any boost or cut at all, weren't they? Modeling the SD 12, is there anything I should try to compensate for?

 

[Robert_J]

The PE BASH amp has an SSF set at 18hz to 20hz. The 500w model is the one that comes from the factory set way too high.

The difference between 300w and 500w in the real world is about 1db. If you didn't push what you had now, then you won't need a 500w model.

All modeling was done with no EQ. Just install the amp and crank it.

-Robert

 

[ShanonS]

I got the BASH from PE and finally had a few minutes last night. When I pulled the Shiva out of the original box, I turned the amp down and left it connected and played it just to see if I could see anything mechanical on the sub indicating what the issue was. I couldn't see anything, but it was still making the same distortion noise. I didn't have time last night to pull the amp out of the Dharman, but I hooked up the BASH amp and the old Shiva just to see what would happen. I used Hellboy II again, where I had first noticed all of the issues, and even turned the dynamic EQ back on (which made the distortion almost constant before). I tried to keep the volume at a very moderate level, but played around with it a little. The distortion was completely gone. Only once did it make any out of the ordinary noise, but even with the volume down the sub was making huge excursions and I'm pretty sure it barely bottomed out or reached it's limit anyway (probably because it was in open air and had absolutely no resistance), it was still nothing like the sound it was making before. So, I think replacing the amp will solve the problem. Now I just need to pull the old one out and see if the new one fits. I'm pretty sure it won't fit horizontally, but I may be able to mount it sideways and not have to fill any holes. If not, then I've got more work to do. Sounds like a good weekend project. Might even be a good chance to use that hole saw I got for a great price and have hardly touched since.

 

[Robert_J]

I'd use a router, aluminum straight edge and large clamps to make perfect cuts that no one will ever see. This is a great excuse to buy new tools.

-Robert

 

[ShanonS]

Well, I pulled the old amp. It's got a square 9.5" hole and a 10.5" square 1/4" recess that it was sitting in. I think I'm going to go with a square 10.5" piece of black plexiglass. I think that will look the cleanest and be the least work for me. It may cost a couple dollars more, but I won't have to worry about cutting anything but the hole for the amp in the plex and won't have to do any painting to make it look halfway decent. Not that anyone sees it, but it also means I won't add any depth or weight to the box.

 

[Andrew Pratt]

I wouldn't use plexiglass...MDF is cheap, takes paint well, is MUCH stronger and easier to work with.

 

[ShanonS]

I got two pieces of black plex cut to the size of the hole for about $20 with shipping. I knew I might mess it up, so I went ahead and got 2. I figured I would try this route and it doesn't work then I can put a 12 or 13 inch square of MDF that will completely cover the hole in the back. No harm no foul. I still think this will look cleaner, so I thought it might be fun. I've never tried working with plex before, so it's just a little experiment. I'm going to Home Depot today, so I already planned on looking for some MDF anyway in case this doesn't work out.

 

[ShanonS]

Just thought I'd give an update. The Dharman is back, with a vengeance. The plexiglas worked great. Got everything right on the first one, didn't even need the back-up piece. It did take a little work and the MDF would have probably been much easier. It did take a bit of work to get the driver itself sealed. I was really surprised how much noise a tiny leak can make even with two large ports. Apparently, when they build these things, they don't use any pilot holes on any of the screws, so after taking out the Shiva putting the new driver in and taking it back out again, there were chunks of the MDF missing around the edge. It's so torn up that I think half of the screws stripped when I turned it so that I was in between the old holes. I finally just went around the outside edge of the new driver with silicone because I was too concerned about pulling it out again. I made a bit of a mess of things, but it sounds great. I'll have to start with a new box if I ever have to remove it for any reason. It was definitely the amp causing the problem. Now I just need to make a 3 inch deep grill for the front. The new driver sticks out a lot more than the Shiva. In fact the current grill actually sits on the surround when installed. I've got some ideas of how I might just make the current grill frame deeper and recover it.

Thanks for all your help Robert!

 

[Robert_J]

You should have used closed cell weather stripping from Lowes or Home Depot. It would have provided an air tight seal and not been as messy.

Glad things are back up and running.

-Robert