VPI scout motor hum.

I posted something concerning this over at the VPI forum. I swear this is like the 3rd rail over there nobody would touch it. I did some research and prominent members here as well as several other forums have had countless issues with motor hum over at VPI.


I think this has been an issue from the start but I was able to (A) tweak it out or (B) I just got used to it and it didn’t bother me anymore. With my AT-OC9ML/II it was at an acceptable level but I just upgraded to a DV-XX2MKII mounted on a new JMW-9T wand it is higher more bothersome. This hum level is actually pretty low and if I have to I can live with it.


I’m posting this because (A) I hope to hear some more tweaking ideas and (B) To get a consensus that this is motor hum not new cartridge and or new wand issues. I can and may go through the trouble to swap arms and see if I get better results but only if experienced members feel it may be worth the trouble. I do have a new AT-OC9ML that I can mount on the new JMW-9T wand and it won’t be to much extra work because this week I should receive my MintLP best tractor alignment protractor and this weekend I plan to tackle that job. I just do not want to remove cartridges from headshells unnecessarily.


Here are screen grabs and audio samples for the most part the images say it all but if someone wanted to listen to the samples to see if I’m being a little anal or if it is worth continuing to try to tweak it out. Saturday I threw some money at it and got the 300 rpm motor and the SDS speed control. I think it helped a little but I had a strange discovery and it is clearly displayed in the grabs and samples.


Sample 1 and image 1 are the same and it is a 2 part sample showing the noise level from the XX2 first prior to the SDS and motor install part 2 shows the OC9.

https://www.sendspace.com/file/u6seio


Sample 2 is after the motor and SDS upgrade and how it is set up now.



https://www.sendspace.com/file/ymvl36


Sample 3 shows my discovery. This is how I initially had it set up. Because my Scoul LE platter is shorter and I had the motor on a piece of cork, I thought it was a little better than a mouse pad with the new taller pulley cause a issue so I had it all the way as low as the belt could ride on the pulley. At first records I played seemed that the hum was much lower and to look at the waveform it did not have that defined constant noise level like in image 1 and 2. In image 3 you can see this and on the records it looked like the hum was gone but the record had a lot of floor noise. What it was the belt was riding so low and was rubbing on the bottom edge of the pulley and this changed the frequency of the noise and kind of spread out over a wider spectrum. When you listen to it you can faintly hear it.

https://www.sendspace.com/file/w0zzy7


So in my mind this is totally caused by the motor and perhaps the XX2 is just more sensitive and I will likely not fix it without a TT upgrade or find a cartridge that is more compliant. As a side note I plan to add a 3g headshell weight because I believe I will need it when I add the extra weight of a Counter Intuitive I have little room to spare now. Is it possible that may help?

 

Are these with or without the needle on a record? What level is the noise at? Are you sure it's not an AC thing? It looks really annoying in iZotope but it's inaudible at my regular listening volume in my living room. Might be worse with cans on.

Here is what my VPI classic 1 looks like hitting the lead in groove of a cheap pressing from 1978. The self noise from the phono stage/cartridge is around -80dB and the lead in around -50dB after normalization of the content.

 

Ohhhh and I forgot to turn off my wireless router for this drop which is the cause of the phono stage noise below 500Hz. Luckily it's waaaaaay buried in the signal.

 

That was a silent track off a test record and yes at normal levels I don't hear it but if i crank it up I can. What bugs me is its worse than the OC9.

 

Had a similar issue with my TNT. The motor sits on the same maple plinth as the deck. A Herbie's Grungebuster, Small Fat Dot, and felt pad, stacked on top of each other, in place of the motor's stock feet completely isolated the hum from playback on speakers and headphones.

(3) Felt furniture pad (3/4"): $4.50 for 20
(3) Small Fat Dot (3/4" dia.): $4.19 ea.
(3) Extra-Thick grungebuster Dots: 3/4" dia.: $1.49

http://herbiesaudiolab.net/products.htm

http://www.amazon.com/Slipstick-CB0...&qid=1430187471&sr=8-3&keywords=3/4 felt pads

I use the remainder of the felt pads under the stock feet on the rest of the equipment in my system. Protects the wood finish on my rack and makes it easier to shift equipment for connections and whatnot.

 

I apologize but I am having trouble comprehending what the nature of the problem is. Are you referring to motor noise that occurs whether or not the tonearm is in the holder or playing the record? Or is the hum dependent on tonearm position?

I had the first problem some years ago which required replacement of the motor. VPI was actually very nice and gave me an upgraded motor. The new motor has been fine for 10 years now. If it's the second problem then it may well be a cartridge TT interaction. I tried a Grado low output cartridge some years ago but it would make a light hum as it approached the deadwax. Other cartridges did not have that issue.

 

I don’t know if it will help but I may try some of those things. The motor is pretty isolated already. I have a sand box and the motor sits on its own piece of glass plus I have it on a piece of cork.


I believe the vibration is transferred through the belt. You can clearly see how by rubbing on the bottom edge of the pulley had an effect on the noise being passed to the needle..

This is after the needle hits the record surface.
I suspect I’m a little nit picky but just didn’t understand why the new XX2 would be worse.

 

I looked at Your files with another software. There are small differences, but to me not that important. But it is clearly so that the hum in all cases are quite a bit above the noise floor, which I personally am not that keen on.

 

mission thanks for looking at them. Did you find sample 3 at all interesting? Here is an image of the pulley with the belt all the way at the bottom the belt was rubbing and that can be seen as well as heard in the sample. This suggest to me that it passes through the belt.

 

Yes, one can see on the plot that it effects the frequences from around 150Hz up to 600Hz with up to 15dB higher noise.

 

As a quick/cheap test, place a mouse pad under the motor (along with the cork). If it attenuates the hum further then you know you are on the right track. This was how I found the source of hum with my initial setup.

 

I think you are on the right track as best as I can tell. There is some issue with the motor either the elements or more likely the alignment and posture of the housing. I think you need a new motor. You should not be hearing that kind of hum and certainly not at the lead in grooves. Because you are hearing it with different type cartridges that points in the direction of the motor.

 

The only thing is the samples are from 2 different motors the original 600 rpm and the new 300 rpm it is an upgrade of sorts. You use the same motor housing box and switch out the actual motor and pulley. It may be that the problem is some how the box.

 

You guys got me thinking and I remover the cork and cut 4 pieces of 3/8 window foam to go under each foot it nearly completely removed it in the left channel and significantly lowered it in the right.

 

Good point. The box dimensions may not be exactly on spec with the TT. I had an issue with my first VPI many years ago where the belt rode too high on the platter side because of a slight height mismatch of the motor with the platter. It was impossible to lift off a record without dislodging the belt. The fix was simple enough by getting taller sorbothane supports for the plinth. But since you are using the same housing with different motors it doesn't seem that the motor itself is the problem. Rather the interaction of the housing with the TT is the constant factor .

 

I had the biggest improvement with window foam . I'm going to try Herbie's baby booties Maybe a 1/2 inch. I may give some thought to getting some of his TT feet

 

Glad to see you are getting results. The 300 rpm motor is a definite improvement over the earlier one. It does make start up a bit more sluggish of course.

 

@ghost rider & @nitsuj - any chance you can post some more detailed pics of the entire thing? I have a HW-19 MKiii and the hum is killing me. The prior turntable had zero hum and everything else is the same. I do not have the SAMA, but I am hoping to try some of these isolation methods. I really only here the hum on headphones, but it's there no matter what I do. Kind of sucks to be honest. Put the old table back and and ZERO hum, same cart too. I am not the most skilled at these things, picture would really help.

 

I strongly suspect this. I had a TNT and heard what could be described as a hum, but I would call it vibration, as it was clearly motor vibration transferred through the belt. Different motor, SDS, motor isolation, belt tension--changing these had an impact but never fully eliminated the vibration, and won't since the motor is always connected via the belt. I had to sell the TNT so I can't offer a final solution. Curiously, I now have a Scout and only occasionally hear the same thing, but my ears are older.

One suggestion--and perhaps counter-intuitive--would be to take off the rubber feet and have the motor sit on some Symposium Point Pods (or Fat Padz if you can deal with the height). The idea would be to drain energy from the motor housing before it's transferred via the belt. I've also had some success with putting EAR IsoDamp material between the motor and the housing, and not tightening down the screws too much.

If you can't get past it perhaps the only solution would be a cogless DC motor, something like the Origin Live motor upgrade. Unfortunate given the money you've already spent on the problem.

John K.

 

Vibration from the motor housing itself was also part of my original "hum" problem. If I lightly placed my finger on the motor housing I could feel a very faint vibration. What I did not know was whether the vibration was traveling through the belt to the deck, or from the maple platform to the deck, or both. Ultimately I never found out exactly because the dual-density Herbie/Felt feet removed the ability to feel any vibration from the motor housing itself and subsequently the platform/belt, literally "drained" the vibration from the motor (presumably converted to heat? Any rocket scientists reading this?). From easily audible hum on speakers, to velvet black on headphones for around $25. I can not emphasize enough how effective this simple affordable solution was. Many thanks to Herbie and Felt furniture feet producers.

Also, no need to remove the stock feet. Just make your new footers a couple mm taller than stock and place them between the stock feet locations directly against the underside of the motor housing.

 

No hum with my Scoutmaster (with 300 RPM motor upgrade). The turntable is on a Gingko Cloud platform, which seems to drain acoustic and mechanical vibrations very efficiently.

 

I would be glad to send you any info I can. What sort of picture do you need? Your TT is a bit different I was looking for pictures and I found this may give you some ideas. Steve over at Herbies audio lab was helpful to me maybe see if he has some ideas for you.
http://www.audioasylum.com/audio/vinyl/messages/57/573521.html

 

So you had noise with the 600rpm?
I’m reconsidering the 300 rpm. How did it help your system?

 

Are you running a speed controller? Would one help with hum?

 

Yes and no it did not. I think it did help the sound in subtle ways and it is way cool I will likely keep it.