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View Full Version : Onix ULW-10 Subwoofer repair help



moris4wildlife
02-26-2014, 12:01 PM
Hello. I'm a new member, but I have owned a pair of CBM 170s for about 10 years, I think. Perhaps the best online purchase I've made, considering all consumer categories. Anyhow, recently I noticed that my subwoofer sounds like crap, after ~8 years of soild performance. They sound totally fried, which is puzzling, since I don't play music past 9 o'clock on the dial; I use a NAD C370 Int Amp rated at 120wpc. I couldn't have blown the cone or anything, so I'm thinking that the amp needs a new capacitor or something. The big problem is that the company I purchased the sub from, AV123, is now defunct, due to allegedly a combination of management and, towards the end, product reliability issues (from what I've read). Any suggestions to where I can find a reliable repair facility? Or maybe an amp kit so I could do it myself? I don't have experience in repair, but I don't mind tinkering, when it's straight forward. Any help would be appreciated. I feel like I could trust what comes out of this forum. Thanks.

drbump471
02-26-2014, 05:37 PM
Recommendations:

1) Take the amp off and see if you notice any bloated capacitors. If you are handy, undo the solder to the capacitor and take it to your local Radio Shack / Fry's / electronics store and see if they have one of the same specs. Go home and redo the solder and see if that fixes you issue.

2) If not willing to go that far, maybe try a new amplifier from Parts Express. http://www.parts-express.com/cat/subwoofer-plate-amplifiers/332 Maybe they have one that fits close to the opening of your current amplifier?

3) Local repair shops....let the board know where you live and maybe someone might know of a shop local to you.

Good luck!!

moris4wildlife
02-26-2014, 07:42 PM
Thank you drbump for the suggestions. Given your response #1, I realize I don't have enough electrical background to know the specs of the capacitor and I don't solder very well. I thought that maybe it was something that could be easily pulled off and a new one plugged in. So, the DIY route may not work for me after all. I checked with the link you provided for Parts Express. I'll study that and see what comes up. I'll likely end up with more questions on how to match the map with my driver. I wonder if it's just a matter of matching the power output. As far as #3, I live in the Monterey Bay area of California, where it's finally raining; we need it bad. Anyhow, thanks for taking the time to reply. It gives me something to think about. I may be back with more questions, later.

Based on your link regarding plate amplifiers and looking into the capacitor issue more carefully, I think the best path would be to see if I can locate the bad capacitor and replace it. It would definitely be the least expensive. I've got some time today to open up my sub. I'll report back with my progress later.

drbump471
02-27-2014, 12:00 PM
Agreed on your final statement. Can't hurt much to see if you locate anything wrong. If you can get the capacitor out of the board, your local electronics store can read it to find out the specs of it and hand you a replacement.

If you got it out with little trouble, I have faith you can get it back in. Worth a shot and then you can go down the new amp route if that doesn't work out or have an estimate for what it would cost to have it fixed by a repair shop.

Let us know how it goes!

davef
02-28-2014, 02:53 PM
Hello. I'm a new member, but I have owned a pair of CBM 170s for about 10 years, I think. Perhaps the best online purchase I've made, considering all consumer categories. Anyhow, recently I noticed that my subwoofer sounds like crap, after ~8 years of soild performance. They sound totally fried, which is puzzling, since I don't play music past 9 o'clock on the dial; I use a NAD C370 Int Amp rated at 120wpc. I couldn't have blown the cone or anything, so I'm thinking that the amp needs a new capacitor or something. The big problem is that the company I purchased the sub from, AV123, is now defunct, due to allegedly a combination of management and, towards the end, product reliability issues (from what I've read). Any suggestions to where I can find a reliable repair facility? Or maybe an amp kit so I could do it myself? I don't have experience in repair, but I don't mind tinkering, when it's straight forward. Any help would be appreciated. I feel like I could trust what comes out of this forum. Thanks.

Hi Moris4wildlife,

Based on your description of the problem, how do you know that you are not having a woofer issue? if you can better describe what you hear, I might be able to assist you with determining if it is the subwoofer amp or the woofer. It is highly doubtful that the problem is capacitor related.

In addition, there is quite a bit more to a subwoofer amp than amplification. The ULW-10, being a sealed subwoofer, has a tremendous amount of EQ in the pre-amp stage. This is key to get the subwoofer to provide a reasonably flat response with decent deep bass. Without this EQ, the subwoofer will not perform well. Because of this, I only recommend replacing the amp with another ULW-10 amp, or if the problem is amp related, having it repaired.

moris4wildlife
02-28-2014, 05:31 PM
Thank you David for replying. Well, I opened up my sub yesterday and saw that all the capacitors looked good. So, you're probably right in that this is not a capacitor problem. I did find a burned fuse and replaced it. It worked beautifully for the evening. Then this morning when I tried to play music, I heard a deep thud, then sub quit on me. I turned on the stereo again and heard the same crappy sound, like the sub is really straining. So, I turned it off, opened it up and saw that the fuse was OK. So, it wasn't a fuse problem, either. The reason I'm thinking it's not a woofer problem is that it can still play beautifully, for short periods of time. Seems like something isn't regulating the voltage or something. I can't get another of the same sub, because the company is defunct. I hope it's a matter of replacing something on the amp. After looking at replacement amps, I saw that I couldn't find anything that would match, so that's out of the question too. If all else fails, it's time for a new sub. Any clues as to what's going on?

After re-reading your reply, I'm curious about the comment on the amp for my sealed subwoofer needing a high amount of EQ. The amp does have an automatic SOS. The replacement amps I've looked at do not. Will this be a problem?

drbump471
02-28-2014, 06:26 PM
Bummer on all the troubles! While I was reading that I was hoping your fuse did the trick.

Dave - Would the old 9V battery to the woofer trick help diagnose if the woofer were bad? Though moris4wildlife says the woofer works great every now and then.

After a quick Google search - http://audiodane.dandk.org/ufw10ulw10-plate-amp-replacement/ maybe that blog will shed some good light for you?

moris4wildlife
02-28-2014, 09:17 PM
Yeah, I thought I nailed it with the fuse. Darn. I'll check out the link on audiodane. Thanks for hanging in there with me drbump.

Well, so, so close, but no cigar! The amps that were being offered by parts express are no longer available. Rats! From a couple of reviews from the website, and the link to the blog you provided, it seemed very promising; a simple, drop in, connect and screw down would've been all that was necessary. The amp itself would not have been a direct replacement and I would've missed out on variable phase control and a built-in EQ, but it seemed that it was the closest I could've gotten to the original. I'm still hoping for a fix.

BTW, I put the sub together again and played it last night and the music sounded great again. Weird.

davef
03-03-2014, 07:11 PM
Yeah, I thought I nailed it with the fuse. Darn. I'll check out the link on audiodane. Thanks for hanging in there with me drbump.

Well, so, so close, but no cigar! The amps that were being offered by parts express are no longer available. Rats! From a couple of reviews from the website, and the link to the blog you provided, it seemed very promising; a simple, drop in, connect and screw down would've been all that was necessary. The amp itself would not have been a direct replacement and I would've missed out on variable phase control and a built-in EQ, but it seemed that it was the closest I could've gotten to the original. I'm still hoping for a fix.

BTW, I put the sub together again and played it last night and the music sounded great again. Weird.

If possible, can you please post a pic of the amp? I might be able to point out what I suspect the bad component to be, just from the layout of the PCB.

moris4wildlife
03-04-2014, 01:56 PM
If possible, can you please post a pic of the amp? I might be able to point out what I suspect the bad component to be, just from the layout of the PCB.

Thank you for persisting with this. It's refreshing, yet not surprising, considering your apparent passion for sound reproduction. I've attached three photos of the amp - back, top-down and oblique views - hoping this would help with your assessment.

BTW, I've been in awe reading the reviews on the Sierra 2s. I've been thinking, even though I've been thoroughly pleased with the first edition CMB 170s for the past 10 years, wouldn't it be nice to crank up some hard rock and hear no distortion in the highs? I can't fathom this concept from a bookshelf speaker, no distortion in the highs?! (at least that's what I'm reading). I'm so anal about things like this, now I'm thinking about saving up for the 2s, despite them being out of my price range. But, then again, what's more satisfying than listening to the quality of sound that is exhilarating, euphoric. Congratulations.

Geez. I forgot to attach the photos of the sub amp; got to carried away thinking of the 2s.
1070
1071
1072

curtis
03-04-2014, 03:11 PM
BTW, I've been in awe reading the reviews on the Sierra 2s. I've been thinking, even though I've been thoroughly pleased with the first edition CMB 170s for the past 10 years, wouldn't it be nice to crank up some hard rock and hear no distortion in the highs? I can't fathom this concept from a bookshelf speaker, no distortion in the highs?! (at least that's what I'm reading). I'm so anal about things like this, now I'm thinking about saving up for the 2s, despite them being out of my price range. But, then again, what's more satisfying than listening to the quality of sound that is exhilarating, euphoric. Congratulations.
The tweeter in the CBM-170SE (as opposed to the ones that were in the "classic" CBM-170) would also be an improvement in that regard.

That said...I think the Sierra-2's are VERY special.

moris4wildlife
03-04-2014, 04:11 PM
The tweeter in the CBM-170SE (as opposed to the ones that were in the "classic" CBM-170) would also be an improvement in that regard.

That said...I think the Sierra-2's are VERY special.

Hi Curtis - Thank you for the suggestion. It is more realistic and practical for me. If you think the upgrade will be noticeable, I will seriously consider it in the near future.

davef
03-04-2014, 11:08 PM
Looks like the middle PCB is the amplifier section. Although it is hard to tell from this angle, the middle PCB looks like it has 2 output transistors. Typically, each of these will have 3 leads that will be soldered to the PCB. They will also be securely mounted to the aluminum backplate (which acts as the heatsink). There will either be a heat conductive pad between the backplate and the transistor, or heat conductive grease (thermal grease). I recommend replacing both of these output transistors with the exact same transistors (as labeled on them) or finding a generic. I suspect the problem occurred due to poor heat sinking of the output transistors, which cause these IC's to fail -- typically due to internal solder joints breaking down, which is why the sub might work for a short period of time but after it gets warm, problems occur as the heat causes things to expand and conductive connections break down.

Depending on the transistors, they can be as inexpensive as $10 each (or less) and its worth trying to replace them.

Good luck and hope this helps!

moris4wildlife
03-05-2014, 10:27 AM
Thank you David. Seems like I may have a solution. I will take your instructions to a qualified electronics repair person, then cross my fingers. I'll report back later.

Oh. I just remembered another question regarding the amp. Will changing the output transistors remove the very audible hum I've always heard through the sub? All of my other components are very quiet.

moris4wildlife
03-27-2014, 09:44 PM
Well, just prior to taking the amp to the electronics shop, I took the speaker cone to a speaker repair shop to assess the subwoofer, just in case Dave was correct about the possibility of the speaker being fried (as he mentioned in an earlier post). She hooked up the speaker to her testing equipment and gave it some juice in a variety of frequencies, while I was holding the speaker. My hand was jumping and shaking but the speaker sounded clean; not a trace of a loose component. In fact, she was quite impressed with the clean sound and depth at which the little 8-incher could produce; she ended by saying that "it's definitely a keeper, the problem is not the speaker". So, I later dropped off the amp at an electronics shop, but got a call a few days later from the tech who said he didn't want to try and figure it out; that it would cost more to try and repair the amp than purchasing a similar one. So, this is where I stand now. I am looking to purchase a Dayton 250 plate amp that will drop right in; no modifying the box and the screw holes will match. Seems like a few HSU owners have used this amp with good success, so it's likely what I'll do. Just wanted to put some closure to this thread. Thanks to all for your advice.

September 4 Update- I purchased the Dayton SPA 250 from Parts Express and have used it for about 5 months. So far so good. The sub sounds tight, clean, musical and punchy. Now I hope it holds up. There seems to be a small percentage of amp failure with this model, based on reviews by other owners.

moris4wildlife
03-30-2014, 03:41 PM
The tweeter in the CBM-170SE (as opposed to the ones that were in the "classic" CBM-170) would also be an improvement in that regard.

That said...I think the Sierra-2's are VERY special.

Curtis - Just curious, but what difference do you hear in the sound of the 170 SE vs the original? I will audition the SE when I'm down in SoCal in two weeks. I'll also listen to the Sierra 2s, knowing its out of my budget, but I would like to hear how special they are.