Question Speed ‘glitches’ on Clearaudio Performance DC - Help!

DT79

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I’ve started experiencing a weird and concerning issue in the last few days and was hoping for some pointers.

I’m using the above turntable with an aftermarket upgraded power supply from MCRU (I know, I know, but the supplied wall wart was just so cheap it became an itch I just had to scratch and in fact I am convinced that the pitch stability has been better with the MCRU PS - until now...)

I’ve been using this new PS for several months and not had any issues up until now.

In maybe the last week every now an again I’ve noticed the pitch will go funny (i.e. the platter seems to slow down for a second or two and then return to normal). It’s done it maybe once per listening session over the past few days.

Within the past few weeks I’ve tweaked a number of things which I don’t think can be connected, but I’ll list them anyway in case they trigger a thought in anyone more knowledgeable than me:
- Adjusted the platter speed setting slightly as I realised it was playing a touch slow (this is achieved via an adjustment screw on the back)
- Made iterative adjustments to VTA (and therefore VTF) to experiment with getting the best sound (settled on a slightly raised VTA)
- Realised that while I had it set-up temporarily for a few weeks while decorating our lounge that I’d connected the MC transformer and phono pre-amp in the wrong order (I.e. TT > phono pre > MC transformer > amp) It was like that for maybe 3 weeks. It didn’t sound as good and the noise floor was higher which at the time I put down the fact that the TT was on the top of the rack and not its wall shelf, and consequently I didn’t play it very much. Everything seemed fine and back to normal once reassembled properly and on the wall shelf in the lounge so I concluded no harm done.

What is the most likely cause in peoples’ opinion? Incoming mains fluctuation? Dodgy aftermarket PS? Belt slipping? Motor on the way out? Something else?

I know the first thing to try is to reinstate the stock PS and see if it keeps happening. Any other trouble shooting steps that anyone can suggest if it does persist?

Thanks in advance.
 
Only change one thing at a time and test otherwise you will not know what is having any effect. Sounds like your expensive PSU is failing.
 
MCRU power supplies are well regarded, but that doesn't mean it can't be faulty. So yes, definitely switch back to the wall wart and run with that for a while to see if the same thing happens.

But it does also sound like the effect of a slipping belt - a brief slowdown in speed until the belt binds again. Saying that, a little while ago I tracked down a similar speed wobble to a worn bearing.

So, it could be a number of things. As larkone says, change one thing at a time - starting with going back to the wart.
 
Only change one thing at a time and test otherwise you will not know what is having any effect. Sounds like your expensive PSU is failing.
MCRU power supplies are well regarded, but that doesn't mean it can't be faulty. So yes, definitely switch back to the wall wart and run with that for a while to see if the same thing happens.

But it does also sound like the effect of a slipping belt - a brief slowdown in speed until the belt binds again. Saying that, a little while ago I tracked down a similar speed wobble to a worn bearing.

So, it could be a number of things. As larkone says, change one thing at a time - starting with going back to the wart.

Thanks both. PSU is swapped back to original for now and we’ll see how it goes.

I did wonder about the belt, but it’s only a touch over 2 years old. I don’t see how a belt could wear out in that time, even with daily use.

I don’t think it can be the bearing as the Performance doesn’t have one as such, it has a magnetic ‘bearing‘, so the platter is simply held in place in the lateral plane by a ceramic spindle. That may be due a top of oil thinking about it, so that can be next thing I try if the issue persists, but I can’t see that being it.
 
So far so good with the standard PSU reinstated. I also applied the 2-year drop of oil to the spindle. My wife and I both reckon we heard a 'wobble' early on, but she was napping and I was reading and not really paying attention, so neither of us is sure. I've played it a lot on Sunday and yesterday evening and nothing else untoward.

On balance this is good because if it was a problem with the motor that would obviously be much more of a PITA to resolve. Although I do have a niggling suspicion that the pitch stability isn't as good with the standard PSU. Intellectually I know that it shouldn't be any different, especially with the fly-wheel effect of the heavy platter, but I have it in my head...

Out of interest, what is the expected life of a belt? I had a good look at it when I had the platter off and it seems in good condition. There was some slight discolouration to one side, but it didn't seem to be perished or polished smooth or anything.
 
Damn it, i spoke too soon, it just did it. Ugh....

Any suggestions of what to try next?

A new belt?
 
Forgive if already mentioned/done, use Isopropyl alcohol to clean the belt. Handy to have around and doesn't cost much. You could mark the belt and platter to see if there is any slippage.
 
Clean the pulley surface too as this does accumulate deposits from the belt over a period of time. A decent belt should last 3-5 years. Assuming nothing is catching/rubbing I would suspect either the motor or supply electronics. Can you get it back to the dealer for checking if no progress?
 
Clean the pulley surface too as this does accumulate deposits from the belt over a period of time. A decent belt should last 3-5 years. Assuming nothing is catching/rubbing I would suspect either the motor or supply electronics. Can you get it back to the dealer for checking if no progress?

Thanks, will clean belt and pulley tonight.

Eliminated power supply by trying 2 different ones.

Returning it to the retailer will be a pain because I originally travelled to a retailer hundreds of miles away so I could audition this TT alongside another I was considering. If necessary I'll have to box it up and post it back. Unless Clearaudio let me return it via a local retailer (there is one) given that I'm now into their extended warranty period.
 
use Isopropyl alcohol to clean the belt
Clean the pulley surface too as this does accumulate deposits from the belt over a period of time.

Well well well. I think you guys were spot on. I cleaned both belt and pulley (a lot of residue came off the belt, a little off the pulley), and fired it up and immediately the pitch stability sounded generally better. I haven’t listened for long enough to be sure that the noticeable speed glitches have stopped happening, but one thing I did think was that it sounded like it was running faster. Checked it against a digital source and sure enough it is.

Now, I mentioned in my OP that I’d tweaked the platter speed a few weeks ago because it was running a bit slow, so I wouldn’t be surprised if that, general pitch stability and the glitches were all down to a dirty belt/pulley causing slippage of the belt.

I can’t believe it, I got this TT brand new 2 years ago, I would never have guessed that this would be a problem.

Thanks for the help. Hopefully I’ve cracked it. Now off to tweak the speed again!
 
Depending on where you live (and even more if you smoke), dirt can quickly build up and cause havoc. I have to vacuum my speakers regularly (and I don't smoke).

Sounds like you should schedule a yearly TT clean as part of the spring cleaning.
 
Depending on where you live (and even more if you smoke), dirt can quickly build up and cause havoc. I have to vacuum my speakers regularly (and I don't smoke).

Sounds like you should schedule a yearly TT clean as part of the spring cleaning.
We don’t smoke. We do have a wood burning stove in the lounge, but if it was that you’d expect to see a film of soot covering everything. Westie hairs are the biggest source of contamination in our house, but they weren’t the culprit in this case.

Hey ho, an annual spring clean it is!
 
Well well well. I think you guys were spot on. I cleaned both belt and pulley (a lot of residue came off the belt, a little off the pulley), and fired it up and immediately the pitch stability sounded generally better. I haven’t listened for long enough to be sure that the noticeable speed glitches have stopped happening, but one thing I did think was that it sounded like it was running faster. Checked it against a digital source and sure enough it is.

Now, I mentioned in my OP that I’d tweaked the platter speed a few weeks ago because it was running a bit slow, so I wouldn’t be surprised if that, general pitch stability and the glitches were all down to a dirty belt/pulley causing slippage of the belt.

I can’t believe it, I got this TT brand new 2 years ago, I would never have guessed that this would be a problem.

Thanks for the help. Hopefully I’ve cracked it. Now off to tweak the speed again!

That is good news. I'm pleased that it, hopefully, has done the trick. Happy listening.
 
We don’t smoke. We do have a wood burning stove in the lounge, but if it was that you’d expect to see a film of soot covering everything. Westie hairs are the biggest source of contamination in our house, but they weren’t the culprit in this case.

Hey ho, an annual spring clean it is!
The wood burning stove will emit many pollutants, not just soot, so you've likely identified the culprit. Is your wood stove choking you? How indoor fires are suffocating cities.
 
They are talking about pollutants that are emitted by the chimney - a wood burner in normal use is a closed box venting into a chimney, it doesn't vent those pollutants into the room or you would die very quickly.
That‘s a relief! Come the winter I will be paranoid every time we open the door of the stove about what particles and pollutants are being deposited on my precious hi if though (our lungs can fend for themselves).
 
That‘s a relief! Come the winter I will be paranoid every time we open the door of the stove about what particles and pollutants are being deposited on my precious hi if though (our lungs can fend for themselves).
Every time you open the door to put new fuel on that will be some fumes getting into the room. Hot air rushes into the void of cold air when the door is opened. You can get pollutants escaping in this way. Not dangerous to your health but more dust than you will actually see. That hot air that hits you in the face when you open the door is not just heat it has other elements in it as well.

The longer you leave the door open to put new fuel in then the more escapes. It's something you'll always have to put up with. The dangerous monoxides are still vented up the chimney when the door is closed and opening the door releases very few, certainly no danger to the household. It's the bits of pollutants that build up over time make for the dust.
 

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