[vman71]

Hi,

Is this possible:

Current Set-Up:
CDP
Tube DAC
Passive Preamp
Chip Amp
Speakers

I installed a tube DAC that I just received into my system and have now discovered that one woofer in one of my speakers is not working correctly.  The woofer just makes a funny noise, it's normal on the other speaker's woofer.

During shipment, the tip of the tube broke and did not visibly show itself (i.e. seeing the white, smokey look in the top of the tube) upon initial inspection.  So when I powered everything up, the bad/broken tube made itself evident with sound that was very wrong and the visible broken tip and white, smokey look.

I opened the tube DAC and replaced the tube with a known good and with a new pair of speakers, the spound is amazing.

So, my question is can the bad tube have caused the woofer to get damaged?

[richidoo]

If there was no loud bang then the DAC did not damage the speakers. Not many chip amps can damage a woofer, unless a string of paralleled 3886s? But even then you need a LOT of gain, sounds like you don't have a preamp so you're probably 40dB or less. If it is Tripath, clone or similar no way it could damage a quality woofer unless you heard something wacky happen.

Did you try the suspected broken speaker again after fixing the DAC? Yourpost is not clear whehter you tried the new tube with both pairs of speakers.

If it still doesn't sound good, test the woofer for mechanical rubbing by pushing it in gently with your finger on the exact center of the driver, on the ductcap. If you feel or hear any rubbing, contact the mfg for replacement to your defective driver. If there was no big bang then it is just a driver defect. If there was a bang, could have stretched something, but not many chip amps can do something like that.

If you still have a problem, please report what speakers, what chip amp. ALso, please check that all your wiring is tight, clean and correctly patched.
Rich

[vman71]

The chip amp I believe is based on a single 3886 and output is 65watts.

Did you try the suspected broken speaker again after fixing the DAC?

Yes, with the bad tube in the tube DAC, there was basically no sound and the sound that was there was all kinds of wrong.  After I put the new/known good tube in, the sound was good but I still detected something just not quite right.

First it was that the imaging was just slightly off.  Then the next song brought out the weird noise from the woofer.  After putting my ear closer to the woofer, it was clear that there was a strange noise with every motion of the woofer.

I swapped my speakers for another pair and all was right in Camelot.

Test the woofer for mechanical rubbing by pushing it in gently with your finger on the exact center of the driver, on the ductcap. If you feel or hear any rubbing, contact the mfg for replacement to your defective driver.

I did your test and sure enough, there was a mechanical rubbing sound.

Either way, I have to replace the woofer.  Would it be recommended to replace both woofers?

The speaker (woofer) was working fine before I inserted the tube DAC with the bad tube.

[vman71]

I guess I'll never truly know if the tube going bad caused any damage or not.  What I do know, is that I'm going to have to replace one driver and see if that fixes things.  I'm not sure how to test the tweeter to see if it is damaged in any way?  Suggestions?

[richidoo]

Driver rubbing is a common defect. There is software that driver mfgs use to look for minute rubbing during QC. Driver efficiency is affected by the gap size so they try to make it small, but that increases chance of rubbing. When a driver breaks in, it changes mechanically. A driver that might have just barely passed QC could finally start rubbing after break in.  Mechanical things change over time, so you never know what happened. If it is a reputable high end speaker mfg, they should give you a new driver for free, but it must match the other side. If they can't match it by checking their records then you might need two. If it is not a high end speaker mfg, you have to use written warrantee, which is probably only 1 year.  You can buy a replacement driver or pair, from an online speaker parts seller. Madisound, Parts Express, e-Speakers.com, US Speakers.com. Madisound can match a pair for you. Or you could ask Rick Craig at Selah Audio for help finding some new drivers.

What speakers do you have?

[vman71]

The speakers are Meadowlark Swallow's.  I know that Meadowlark is no longer in business.  What I'm gathering is that the woofer is a Vifa 4.5" 8ohm or something identical from a company called Logic.

I don't mind buying a new pair that are matched.  If I'm going to do that, I would want to see if I can upgrade from the current woofer to something of better quality that still matches the Vifa tweeter.

[richidoo]

You can pull one woofer out of the cabinet and get the part number. Then google the part # for replacements, or email Madisound for advice on replacement, or PM Rick for suggestion on an upgrade driver that sounds even better. Tymphany website returned no results searching Vifa Logic.

http://www.audioasylum.com/scripts/t.pl?f=speakers&m=198444

[vman71]

Thanks for all your help, advice, and suggestions.  I'll see if I can pull the bad driver tonight for a part number.

The good news is that the addition of the tube DAC (maker unknown - DIY) has made a very nice impact  to the sound of my system as only tubes can do.  That coupled with the fact that it was very affordable given the quality, craftmanship of the build, and parts used...all-in-all a good audio move.

I'll also mention that I'm surprised at how much a cheaper DAC can improve the sound given that I was using a very nice CDP to start with.