Woofer output low.

Jetmaker737 · June 16

Hey folks. Today I sold my ~15 year old Sonus Faber Cremona speakers. The buyer drove 10 hours round trip to pick them up. He called me this evening to say that he hooked them up and one (of 4) of the woofers has low output. So taking him at his word for now... What would be possible causes of this? Bad caps or other components in the crossover? Is it something straight forward to test for?

I had never noticed an issue before, but there are three other drivers between the two speaks, so who knows?

Edited to remove unnecessary info.

F1nut · June 16

It could be as simple as a loose connection due to transport. The driver will produce sound in sympathy, hence the claim of low output.

Jetmaker737 · June 16

Thanks, F1nut

msg · June 17

Just did a quick skim of the stereophile review. Didn't answer my question but I'm curious - do you know whether these woofers are supposed to output the same, or are the speakers designed such that they output differently?

Curious as to whether the latter, and the buyer hasn't noticed the other speaker actually performing the same as the "problem" one?

Jetmaker737 · June 17

It's a good question. I was wondering myself whether one of the two woofer drivers might be passive, but I think not. But even during 11 years of ownership I never looked very closely at the woofer drivers or measured them. The buyer texted me a fuzzy phone video of both speakers playing. On the left speaker you could clearly make out both woofer excursions. On the right you could not. I verified with him that his balance control was centered. He is going to have a friend bring in a different pre and amp to drive them. That should clear his own gear as the problem. Tomorrow he will take them to his tech for more troubleshooting. I asked him to be sure his tech looks for loose connections as F1 suggested.

Jetmaker737 · June 21

I picked up these speakers from the buyer yesterday and refunded him. The speakers sounded great. Before boxing up I took two sets measurements with my phone app. I placed the phone mic approx 6 inches in front of each woofer driver, screenshots below. Circled in yellow are the measurements from the driver in question and green are the others. You can see that the suspect driver has a few dB lower output. Feeling the driver in action you can sense the buzzing and excursion so it seems it must be getting a signal.

There are two 8 Ohm drivers per speaker connected in parallel (therefore 4 Ohms per speaker). Due to the parallel connection I would assume that the crossover would not be the issue here or it would be apparent in both drivers.

Even though it seems the speaker is connected I plan to remove the driver anyways for inspection, but not sure what I should be looking for.

Clipdat · June 21

You took the speakers back? He could have damaged them somehow with inferior equipment (overdriving with not enough power, etc) or shorting out connections and come up with this random story about how one woofer isn't working right, but in reality he damaged the crossover/voice coil or something.

Jetmaker737 · June 21

Clipdat wrote: »

You took the speakers back? He could have damaged them somehow with inferior equipment (overdriving with not enough power, etc) or shorting out connections and come up with this random story about how one woofer isn't working right, but in reality he damaged the crossover/voice coil or something.

That's a scenario I had considered but seemed unlikely given that they performed fine and this issue with the driver is subtle. So I made the decision to take them back. Now I'm simply looking for troubleshooting suggestions. I'm not convinced at this point that there is even an issue.

Clipdat · June 22

Fair enough. I'm just overly skeptical these days after getting mildly shafted recently on a few transactions with less than honest sellers.

I quickly googled Sonus Faber Cremona woofer failure, but I could only find posts of people dealing with woofers that had failed outright, not just partial failures or reduced volume output.

From your description of the issue and your measurements, it sounds to me like an issue with the crossover or an issue with that particular driver or it's voice coil. Then again I don't know very much about troubleshooting this kind of thing. Maybe pulling a good woofer and the "bad" one and checking their measurements with a meter would be a good thing to try at this point?

@VR3 any thoughts?

Gardenstater · June 22

What were the findings of the buyer's "tech" when he took the speaker to him ?

Jetmaker737 · June 22

Gardenstater wrote: »

What were the findings of the buyer's "tech" when he took the speaker to him ?

The buyer said that his tech refused to take them in saying that he doesn't work on speakers. This wasn't a surprise as he had told me this may be the case. He was going to talk the guy into taking them. He didn't succeed.

@Clipdat , I hear what you're saying about scammers and I had some red flags up about this guy. But after talking with him extensively I figured he was legit in believing there's an issue. Also, I didn't want to have to deal with any problems if he filed a complaint through paypal.

Gardenstater · June 22

If you have an ohmmeter, one quick and easy check without having to do any disassembly at all would be to check the DC resistance of each, across the binding posts of the speaker enclosure.

VR3 · June 22

Take a known good driver and install it where the suspect driver is and report back

msg · June 22

That's what I was thinking - swap the two drivers in that speaker and see if the problem follows?
Does look like @Jetmaker737 has a way to test.

If
Yes >> issue with speaker
No >> issue with circuit

Maybe set the speakers up as is first, and confirm that the difference is still measurable in your space with your gear, then the driver swap?

Jetmaker737 · June 22

msg wrote: »

Maybe set the speakers up as is first, and confirm that the difference is still measurable in your space with your gear, then the driver swap?

Yep. That's my plan.

gp4jesus · June 23

msg wrote: »

That's what I was thinking - swap the two drivers in that speaker and see if the problem follows?
Does look like @Jetmaker737 has a way to test.

If
Yes >> issue with speaker
No >> issue with circuit

Maybe set the speakers up as is first, and confirm that the difference is still measurable in your space with your gear, then the driver swap?

Step 1 ⬆️⬆️
Step 2. Swap one or both drivers from the other closure to confirm step 1 results.

Jetmaker737 · June 23

What would be the minimum equipment needed to do the driver swaps? Based on the soldering iron thread I'm thinking a Weller digital iron. Also will need some desoldering braid, Super Wick looks good. Any advice on specific solder, tips etc?

msg · June 23

I hadn't considered that little obstacle - so the driver wiring is soldered to the tabs? not using Fastons?

Jetmaker737 · June 23

Correct. At least according to photos on the internet. I have not yet begun work on the speakers.

VR3 · June 23

For the intents of testing just cut a few inches away and use wire nuts

msg · June 23

Huht, interesting. That complicates your task slightly, turning it into a bit more of an operation. I can see why you're not done yet 😆

For the troubleshooting stage, you could probably just heat and remove the leads, swap your drivers, and either reuse or add a touch more solder when soldering the swap.

For the final reassembly, I suppose it would be best to desolder/clean, and reterminate. If so, then you also likely want to clean and reterminate all connections for consistency?

I vaguely recall another previous soldering thread that had some great photos and tools. One thing was a 3rd hand alternative that I think @jdjohn shared. I was just talking to @Hermitism about this earlier. It's more of a magnetic platform with movable holders.
https://www.amazon.com/dp/B07T7NY1DJ

Just looked up my order for the solder wick I have. Looks like it was an off brand ,which may explain its varying performance and success. Also two generic vacuum solder-suckers - suction only, not desolderers. They work, but I'm sure are not as good as the Haako desoldering tool. If my projects were to ramp up, I think that Haako would be a worthwhile tool.

I've seen people get boards, traces, and soldering pads extremely clean using wick. @SCompRacer and @ALL212 might know of some products that work well. Also @VR3 @F1nut @jdjohn to tag a few others.

I wipe down the connections with 99% iso once complete to clean any residue or flux.

SCompRacer · June 23

The Haako FR301 is great if you are doing volume work, like desoldering numerous caps on a PCB. The Haako has different size nozzles to match what you are working on. I even found it useful working on old tube gear point to point wiring. You clean the vacuum chamber and have to replace the ceramic filter discs as they clog.

I've used spring loaded one shot vacuum solder suckers before I got the Haako. Adding low melt solder or flux to a joint can help with the one-shot solder suckers. Use solder flux to help the wick absorb.

I have an old Weller WES51 that still works well. Lots of hours on it. The tip should match the size of the work. I purchased a Genuine Weller WE1010 tip set, has 5 different tips. Also have a hot air station for doing SMD (surface mount device) chips/components.

99% iso is great for cleaning up flux on joints or PCB. Sometimes pharmacies hide it behind the counter and only have the 90% out on the shelf. Kimtech wipes are good for soaking up the iso/debris.

Solder blob from a Haako.

Jetmaker737 · June 23

Great advice. Thanks, folks. I've got over 200 bucks worth of stuff in my Amazon cart. Going to go pull the trigger on that. Got the Weller WE1010NA iron, a magnetic third hand, some Kester solder (not cheap!), some paste flux and the wick. And the tip set too. And what the heck, got the brass tip cleaner too. Somebody stop me, lol. Guess I'll need to recap my tape decks to justify all this.

msg · June 23

Lol, there's not really anything wrong with these speakers, is there? You just wanted to buy soldering stuff!

I've used some Kester stuff before, and it's okay, but were you aware of the common preference for Cardas Quad Eutectic solder? Easiest stuff I've ever worked with, but does contain lead.

msg · June 23

I knew Rich would have some nuggets to share - and look, even a physical one made of solder.

Good tip on using flux with the wick. I was wondering, after one video I saw a while back, whether one guy was using solder wick with flux in it, because he was getting contacts so clean.

@SCompRacer - when using flux with wick, do you put the flux on the work, or do you add it atop the wick after you've placed it on the work and begun heating it?

jdjohn · June 23

This thread has crossed-over between the questionable woofer, and soldering info. As others have suggested, I would disconnect the woofer in question, and test continuity. Of course, also check for rubbing of the voice coil.

There has been a lot of good soldering information shared here lately in the forum, and I will add my affirmation on Weller soldering irons, and Hakko de-soldering guns. I totally agree on having multiple tips, and variable temperature capability. I actually built a little DIY variable voltage box with a rotary dimmer switch, but if I needed to purchase new, I'd go with a more proper setup.

One little tidbit I will add is using Oakey No.95 Lead-free Tinning Flux paste. It's great for 'dipping your tip' into for tinning/cleaning the iron tip (with a follow-up plunging into a brass wire sponge). It's also great for pre-applying to a solder joint before actually applying solder. Apply it strategically (I normally use a wooden toothpick), and then touch it with a hot iron. It will sizzle and smoke a bit, but in the process, it applies a thin layer of tinning and flux to the joint. This will normally secure the joint a bit (after cooling), and make applying proper solder a little easier.

I will also reiterate that with soldering, as with Boy Scouts, cleanliness is next to Godliness

SCompRacer · June 23

msg wrote: »

@SCompRacer - when using flux with wick, do you put the flux on the work, or do you add it atop the wick after you've placed it on the work and begun heating it?

On a PCB, the board then lay the wick in it. On point to point, I apply to both. Point to point typically has component leads wrapped around a terminal. Once most of the solder is off, I can use a fine cutter to cut lead at the wrap, or 180-degree bend, heat again and leads fall or can be pulled off with tweezers/needlenose. A pointy tool is helpful to unwind wire.

Hope you got just a simple connection problem. A friend sold a pair of KEF's and one stopped working at his buddy's house a half hour away. A wire broke off the xover.

Clipdat · June 24

Dang, surprised the woofer connections are soldered from the factory versus using fastons.

Edit: I guess it's a Sonus Faber thing, I wouldn't understand.

pitdogg2 · June 24

If they were mine they would have fastons should I have a need to desolder the connections. I would crimp the fastons then reflow solder into them.

Jetmaker737 · June 24

pitdogg2 wrote: »

If they were mine they would have fastons should I have a need to desolder the connections. I would crimp the fastons then reflow solder into them.

Not a bad idea, especially if I'm going to be swapping drivers.

msg · June 24

I can't tell from those photos @Clipdat posted whether the tabs are of standard faston-y sizes, and/or whether this would be representative of all SF drivers.

Wouldn't be a show-stopper necessarily; you could make short male faston pigtails from the soldered connections on the speaker terminals by simply snipping the existing wire. Add and solder male and female fastons, and use heatshrink over the female faston.

Woofer output low.

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