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My old Dharman is down, any advice


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#1 of 36 ShanonS

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Posted April 20 2009 - 02:50 PM

Well, I just bought a new receiver - Onkyo 876. I have been messing around with the Audyssey setup, and my sub clipped severly on a scene early on in Hellboy 2. Instead of just leaving it alone, I tried using different audio settings and sound modes to try and eliminate it and it continued to do it. It's damaged now, of course, it is somewhere around 10 yrs old, so it may have just worn out. Now it crackles and rattles at all different levels of bass. It's been a really good sub, and I'd like to just repair it if possible. I've never messed with spearker internals, besides installing new speakers in my vehicles, but I am handy and know my way around a soldering gun. Could it be possible to repair the driver, or replace it, or is it time to just replace the whole thing? I can't really afford to drop another grand on more audio gear right now, or else it would be an obvious time to upgrade. I don't know how much of a chance there is for me to replace the driver and find out there is really something wrong with the amp or something. Any input or suggestions from someone that knows more about building or repairing speakers would be greatly appreciated.

#2 of 36 Robert_J

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Posted April 20 2009 - 11:04 PM

The Dharman is the ported enclosure with the 12" Shiva. I think it used a Kiega 300w amp.

What kind of sound did the sub make? Amps clip. It's just a distorted sound that comes from the speaker. Drivers bottom out. That's a metalic clank when the voice coil former hits the magnet's back plate. Sometimes it is harmless and other times the former gets bent and will start to run against the pole piece. The driver is on the fast path to blowing. If that happens it may take out your amp as well.

What is your budget to get this fixed?

-Robert

#3 of 36 ShanonS

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Posted April 21 2009 - 01:35 AM

You know your subs.

The first time it actually did this was on Miracle at St. Anna, and at what seemed like a very odd point. If you've seen the movie, it was the barn shootout where the big guy first found the boy. The first guys shots sounded normal, then when the big guy shoots, the sub just gave three very loud clicks, but it was like it gave the very loud clicks but all other bass sound was absent. I wouldn't really call it a metalic clank. It didn't sound bad like it did the second time on Hellboy 2, just very odd. With Hellboy 2, it was more like several loud clanks in a row. Now, it makes a crackling sound fairly constantly. It's like it plays mid bass OK, but it sounds like crinkling celophane at times during upper and lower bass. I took the grill off last night when this started, and there were also times with the cone was just jumping all over the place but not much sound coming out, and it didn't seem to be at times when there should be any sub-sonic base (if that makes sense) After this started, I didn't mess with it a whole lot and thought I'd get some advice before I messed around and did more damage. All of this happened with the receiver set at a max of -25, so it's not like I was playing anywhere near reference level. When I was trying to diagnose the issue and trying different sound processing to see if one of them was adding bass boost and causing the clipping, it was down around -30 or -35 and still got the clipping.

When I started setting things up on the new receiver, I changed a lot of settings. I moved the LPF up to max to let the receiver set that without interference. I also moved the volume up a little to see where Audyssey would set trim. It was still below or at mid. I also moved the variable phase all the way to one side since the receiver will also let you know if it's out of phase. I don't know if that could have thrown the old amp off after being set the same for several years.

Oh, at the moment, I probably have just a couple hundred to get the sub fixed, more and it will have to wait.

#4 of 36 Robert_J

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Posted April 21 2009 - 02:16 AM

Quote:
Originally Posted by ShanonS
Now, it makes a crackling sound fairly constantly. It's like it plays mid bass OK, but it sounds like crinkling celophane at times during upper and lower bass.
You have destroyed the driver. That crackling sound is the voice coil rubbing. There is nothing you can but replace the driver.

Quote:
Originally Posted by ShanonS
When I started setting things up on the new receiver, I changed a lot of settings. I moved the LPF up to max to let the receiver set that without interference. I also moved the volume up a little to see where Audyssey would set trim. It was still below or at mid. I also moved the variable phase all the way to one side since the receiver will also let you know if it's out of phase. I don't know if that could have thrown the old amp off after being set the same for several years.
What you did did not cause the problem. Audyssey caused this. Was it in the wrong by causing this? I don't know. I have no idea how your sub was originally set up. Just telling me the settings means nothing. Did you use an SPL meter and a calibration disc to set it up originally? If not, you may have been running your sub too low for years. There are just too many variables to determine what went wrong.

You can replace your Shiva driver with the new Shiva-X from DIY Cable for under $200. It is supposed to be a replacement for the original Shiva but they don't mention it as a drop-in replacement. In the past I've seen cast frame subs that are about 1/4" larger then their stamped steel frame counterparts. Give Kevin a call and ask. He's a very helpful guy. Also, the Shiva-X has 11mm more excursion so there is very little chance you will ever bottom it out.

If you do need to increase the size of the driver hole, then that is easy. I would find someone that is familiar with woodworking to do this though. A router with a circle cutting jig are all that you need. If you were in the area, I could do it for you in about 15 minutes.

-Robert

#5 of 36 ShanonS

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Posted April 21 2009 - 03:03 AM

Thanks a million man. That's exactly what I was looking for. I didn't even know Adire had gone down until I started looking last night. Then I did a search on Shiva and didn't find much. I was worried I coudn't get one any longer. I sent an e-mail to one of the companies listed on the old Adire site as able to service their subs, but haven't heard back yet. I will definitely look into the Shiva-X. Should I replace any of the baffle material or anything else while I'm at it?

Yes, on all my previous setups I used tones from VE or Avia (or something like that) to set the level and even went through all of the bass test tones with my SPL to set the notch filter on my AVR507. What do you mean by running it too low? (just to safeguard the replacement once it's in) Could it be that it was just due for replacement after 8 yrs? (My wife reminded me exactly when we got it after I told her it had most likely bit the dust)

#6 of 36 Robert_J

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Posted April 21 2009 - 04:34 AM

I meant that maybe the levels were too low and now your are asking too much of your sub. But if you set them with a disc and a meter then you are good. More than likely it is the newer soundtracks putting additional strain on the subs. You are going from a 2 wheel drive pickup to a monster truck when you compare drivers. You will not hurt this one with your current amp.

After 8 years you should not have any trouble. I've got Shiva MKIII's that are still going strong. The bass was just too much.

-Robert

#7 of 36 ShanonS

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Posted April 21 2009 - 05:25 AM

I was surprised to see that they went back to a paper cone. Mine looks like a woven material. Guess it shouldn't matter much. I wondered about that too, both of the movies I had issues with were Blu-rays on the HD format.

I'm going to give them a call in the next hour or so and see about ordering the new driver.

#8 of 36 ShanonS

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Posted April 21 2009 - 08:31 AM

I called Kevin, very nice guy. He said this driver is nowhere close to a drop in, nothing like the Shiva. He told me what Partexpress driver to order and said it's basically a copy. It's a Dayton DVC 310. Even looked up the part number and cost for me. Now, my question is, if this is basically the same sub as what I had, will I be back in the same boat with the sub bottoming out? I need to look at the specs when I get home and see if the newer one has the same excursion and everything. One review on the sub said it constantly bottomed out, while others said it was a great sub.

#9 of 36 Robert_J

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Posted April 21 2009 - 10:08 AM

The Dayton driver is a copy in looks and performance but likes a smaller box. I'm finishing up a sub for a family member with one. It will bottom in a large box.

Find out the enclosure volume of your sub. If you aren't good with geometry, find the outside dimensions and the thickness of the box material. Also, measure the diameter and length of the ports. From here, we can find a suitable replacement or see how the Shiva-X models.

I could have sworn that Kevin mentioned the Shiva-X was a drop-in replacement for the older Shiva designs.

-Robert

#10 of 36 Robert_J

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Posted April 21 2009 - 10:13 AM

Found the info - Dharman

109L tuned to 22hz.

-Robert

#11 of 36 Robert_J

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Posted April 21 2009 - 10:53 AM

I modeled a Shiva in your 109L. You have peak output at 22hz of 110.8db.

With an AE Speakers C12.2 - Acoustic Elegance • View topic - C12.2 Poly cone 12" for $75 each !!!
you have peak output of 110db at 22hz. The price is nice and as of last week John still had a few left. The linear excursion is the same as the Shiva but the xmech (mechanical clearances) are larger. You will not bottom this one out with your current system.

Modeling the Dayton DVC 12" (Shiva clone) you are .8db quieter and you will push it even farther to get the same output.

The Shiva-X does look bad in your box. Max output of 107.8db.

The Ascendant Audio Atlas 12" and Blueprint 1201 both look great and have 110 and 110.2db of output respectively. But they are no longer available on the retail market. But some people may have some stockpiled away.

If you want to make sure you can NEVER bottom out your driver, go with this - Parts Express:Audiopulse AX12D2 AXIS 12" DVC Subwoofer 2 Ohm . I run two of the 15" versions in my home theater with about 800w each on them.

-Robert

#12 of 36 ShanonS

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Posted April 21 2009 - 11:09 AM

Is there any reason you would not go with the AE speaker? Would there be any issues using it with the Dharman amp? Remember, the Shiva was wired to give a 4 ohm load and the AE can only be 8 ohm or 2 ohm, and I don't think the amp can handle 2 ohm. Have you used any of these before to have an idea about sound quality?

Thanks again for all your help.

#13 of 36 Robert_J

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Posted April 21 2009 - 01:53 PM

The C12.2 will be an 8 ohm driver but that won't really mean anything. Your amp won't put out its full power but that only translates to about 2db at full power. Really not enough to matter.

As for sound quality, I trust John as a speaker engineer. I have three of his older AV series drivers and they are great. They are much better than the older Shiva.

-Robert

#14 of 36 ShanonS

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Posted April 21 2009 - 02:36 PM

I just have one more, this is what CSS replied back to my inquiry. They said they actually contacted Dan Wiggins and he suggested the SD-12 on this page. Can you see what numbers you come up with for it? Creative Sound Solutions - Loudspeakers, Parts and DIY Speaker Kits

Thanks again.

#15 of 36 Robert_J

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Posted April 21 2009 - 11:41 PM

I forgot about the SD-12. I just modeled it in Unibox and it looks great. Almost like the old Shiva except that it has an extra 3mm of linear excursion. With an xmech of 32mm it is almost impossible to bottom out. And with the Pope of transducer engineering giving it his blessing, you must purchase it.

-Robert

#16 of 36 ShanonS

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Posted April 22 2009 - 02:14 AM

Wasn't Dan the owner of Adire, or somehow involved anyway?

I don't know anytyhing about interpreting the specs. The info on CSS about the driver said something about tuning to 25hz and mainly talked about mobile applications. Do you remember where the modeling showed the peak output on the SD-12. Which would you choose between it and the AE driver?

I'll quit bugging you after this. If you're ever in Alabama, I definitely owe you a beer!

#17 of 36 Robert_J

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Posted April 22 2009 - 03:36 AM

Yes, Dan was the owner of Adire. He is now at ADI - About ADI

The only thing I see with 25hz is the mobile SQL application where they recommend a 25hz subsonic filter. That does not apply to you. Your sub's amp has a subsonic filter that is probably in the 18hz to 20hz range since your sub is tuned to 22hz. That is how I modeled your sub in my software.

With ported subs, peak output will always be at the tuning frequency which in your case is 22hz. It was 110.2db while the original was 110.8db. That is under perfect conditions and doesn't take into account the voice coil heating up. Since the SD-12 has a 3" voice coil, it will stay cooler than the Shiva and probably have more overall output than any of the subs I listed.

You are not bugging me. This is fun for me.

-Robert

#18 of 36 ShanonS

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Posted April 29 2009 - 04:21 PM

Robert,
I ordered the CSS last week, still hasn't made it, but I'm trying to get things ready to make a quick swap once it does make it. Maybe I just don't know how to read the specs provided, but I can't make out a few things from the info on CSS's website. It says it has a 2 layer voice coil. Does that mean it is dual voice coil, or is it considered a single? I also don't see anything on the impedance. Just trying to figure out if I need to consider any wiring configuration on the actual sub before dropping it in. I pulled the Shiva out tonight just to make sure there weren't any internal braces I needed to consider when installing the new driver, but it's pretty much an open box with small side braces and a lot of fill.

#19 of 36 Robert_J

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Posted April 30 2009 - 02:03 AM

A 2 layer voice coil means that the windings are two layers thick. If you look at the pic below, the voice coil is sitting in the black circle (this is a spider spacer if you are interested). It is a 4 layer, 4 ohm, single voice coil.
Posted Image

The resistance is listed as part of the Theile/Small parameters - Re: 3.6. The Re parameter is the DC resistance of the voice coil. Based on this, the impedance is 4 ohms nominal.

From the looks of the driver, it only has one pair of terminals. That would mean it is single voice coil. If it is dual voice coils, then it would be dual 8 ohm or dual 2 ohm. You will have to determine that after you get the driver. We can look at the different options then. But you don't want to wire up a dual 2 in parallel. That would yield a 1 ohm load on your amp and it would fry in seconds.

-Robert

#20 of 36 ShanonS

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Posted April 30 2009 - 04:13 AM

Definitely interested. I did notice that on the physical specs page after I posted and figured that must be the impedance since it had ohm beside it on that page.

That's exactly why I was asking. I knew I needed 4 ohm or up, but preferably 4 ohm to get the most out of the amp. If it's either a single 4 ohm, or some other dual configuration already wired to 4 ohm, then it should be good to go, as long as it fits in the recess for the Shiva. I'm going to measure the spacing on the Shiva's mounting holes when I get home this evening.




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