• The move to the new server is done. There are some software and database maintenance updates in process. This has us passing the hat around to help out. We appreciate any donations. Seriously, even a dollar helps. The payment page may be found here - https://www.audiokarma.org/support.html

Pro-Ject Debut III Hum/resonance problem

Garven

Garven

Active Member
picked up a Pro-Ject Debut III in September and had the dealer upgrade the cartridge to an OM20 Super. The dealer initially offered me a deal on the tt with an Ortofon 520, but when I discussed it with him, he thought for a minute and then suggested that the OM20 would probably be a better match for the tonearm.

I loved how dynamic the whole thing sounded from the outset. Drums seemed to snap with a realism I'd never heard on CDs. The highs weren't as extended as I'd like or the bass bloom as big (although it did seem solid), but I attributed this to needing a break-in period. It's certainly through that now and the highs are better than they were but the bass is still quite lean, and surface noise seems quite apparent.

My biggest issue with the tt right now is a bass "hum" I get whenever the needle comes into contact with the vinyl. I don't think it's an electrical hum because when the arm is up, there's no noise at all, but as soon as the needle is in the groove, there's a slight hum below 100Hz or so that sounds like a resonance issue. For awhile, I thought perhaps this was just a limitation of the Debut III's design, but perhaps it is cartridge-related. Anyone else experience this?

If it is cartridge related, is there anything I can do with the OM20 adjustment-wise to improve this or am I going to have to go for something else?

Here are a couple of samples of my hum problem.
http://stevethomson.ca/samples/hum1.wav
http://stevethomson.ca/samples/hum2.wav

Notice that on the first one, the bass hum seems to sound like an off-center LP, in that it's intermittent. On the second one, it's more even, which is what I usually get.

Any ideas?
 
Register to hide this ad
Are you sure the cartridge isn't simply mistracking?

I listened to both your samples and I can't hear any obvious hum...perhaps it's my computer speakers - everything sounds damned bad through my computer:D Seriously, I don't hear anything off in these clips.

You could try upping the VTF if you think it may be mistracking - mistracking often will cause a buzz in both channels that appears non-electric in nature.

What's the associated gear here? What pre, what amp? Have you checked all the cartridge related alignments?

Jeff
 
Yes, it's definitely there. I posted this same message to another forum and folks there said it sounded like a motor problem.

I've tried various VTF settings but they haven't changed the hum. The pre is a Cambridge Audio 640P going through a Yamaha receiver. However, I doubt these are the culprit as the sound was also there when I first purchased the tt and ran it through the phono stage of a mid-90s Fisher receiver.

I might also add that I've experimented with stylus cleaning by dropping the stylus gently into a block of Magic Eraser. When I listened to this, I noticed that as soon as the stylus sets down in the block, the hum appears. The only thing I haven't checked yet, as suggested on the other forum, is whether or not the hum appears if I lower the stylus onto vinyl with the motor turned off.

Thanks for the reply.
 
Well since I'm listening to the Pro-Ject Debut III as I type and am experiencing no such problems, I'd start by checking the carts alignment. Not with the cheesy alignment tool you get with the table but with a nice mirrored alignment tool. Sure sounds like mis tracking to me.

Mike
 
Alignment wouldn't produce hum if the stylus is just sitting in a stationary object like the magic eraser block.

Actually, I just tried sitting the stylus down on vinyl with the motor not running. There was no hum. I even carefully turned the record with my finger on the label and it was silent. I sat the stylus back into the erased block and again silent. As soon as I started the motor, the hum was back. It's definitely motor related.
 
Did you check all the connections from the headshell/tonearm wires to the cartridge? Next I would check the IC's from the TT to the receiver or phono pre-amp. Does your TT have a ground? I had a hum from my TD 160 at the male plug end which was a frayed wire but hidden by the end cap on the plug. Good luck. Brien
 
So recapping,
1. It's a new turntable.
2. Hum occurs only when motor is on and stylus touches something.
Logically, it sounds like it's an function issue with the stylus/cartridge (not an alignment issue). Otherwise the hum would be there all the time. Do you have another cart you can use to test the table?
 
As Hakaplan says it would be nice to swap cartridges and see if the problem follows.

Like Bullwinkle, I'm thinking ground issues. Check that your arm wire is grounded properly - if it's connected to a ground pin on your phono stage, take it off and then turn the motor on. I've had some strange things happen with ground wiring, depending on the system. Sometimes it's better to leave the ground wire off believe it or not.

Good luck.

Jeff
 
Garven said:
As soon as I started the motor, the hum was back. It's definitely motor related.
Click to expand...


Do you have a poewr conditioner attatched to your setup? In any case if you suspect motor noise I would guess any cart would pick it up. I'd return the TT if possible.
 
jmathers said:
As Hakaplan says it would be nice to swap cartridges and see if the problem follows.

Like Bullwinkle, I'm thinking ground issues. Check that your arm wire is grounded properly - if it's connected to a ground pin on your phono stage, take it off and then turn the motor on. I've had some strange things happen with ground wiring, depending on the system. Sometimes it's better to leave the ground wire off believe it or not.

Good luck.

Jeff
Click to expand...
But Jeff, it only hums when the stylus touches something. If it was a ground problem, as soon as power was switched on it would hum. It sounds very much like the Technics/Grado syndrome where the unshielded Grado cart is affected by the Technics motor and causes hum. I'd lay bets that the cart has a problem.

If he can just get his hands on a cheap AT or Shure cart (because they seldom hum) just to test, and it still does it, then my money goes on the motor being defective.
 
hakaplan said:
But Jeff, it only hums when the stylus touches something. If it was a ground problem, as soon as power was switched on it would hum. It sounds very much like the Technics/Grado syndrome where the unshielded Grado cart is affected by the Technics motor and causes hum. I'd lay bets that the cart has a problem.

If he can just get his hands on a cheap AT or Shure cart (because they seldom hum) just to test, and it still does it, then my money goes on the motor being defective.
Click to expand...

Your thoughts on it unlikely being a grounding problem match mine. It wouldn't make sense. Plus, there is no "buzz" to it like a grounding problem, it's very acoustic in nature. After trying a few different tests myself last night, I've pretty much concluded that it's related to the motor. It's almost like the stylus is completing some sort of microphonic/acoustic feedback loop with the motor.

I called my dealer this morning and arranged to bring it in tomorrow. He's going to keep it for a couple of days and run some tests to see if the motor needs to be replaced.

I'll post the results once I know more.

Thanks for your help.
 
I visited the dealer this morning and, in his view, there is no problem with my tt. He placed it on a decent stand and we listened carefully. There is a very faint rumble but nothing as loud as I've heard at home. He seemed to feel that it may be a case of my physical setup creating resonance that's being picked up and amplified by the cartridge/arm. He's expecting his next stock of Xpressions in next week and offered to let me take a demo home to try. He also gave me some reasonable terms for a trade on an Xpression.

I wasn't planning on putting any more money into audio for another few months, so I'm going to see if I can track down what's causing the resonance first. I've got the tt sitting on a middle shelf on an Ikea "Bonde" shelving unit with a shelf full of albums on the shelf below and a receiver & disc player on the shelf above. I did have my phono stage (Cambridge Audio 640P) sitting up next to my receiver. I'm wondering if moving it down to the same shelf as the tt might help.

Any thoughts?
 
They're on another wall. However, the problem does not come from them because I listen mostly through headphones and often do transfers to PC for making car CDs, home DVD-As, etc. The hum is definitely there then even without the speakers.
 
Garven said:
They're on another wall. However, the problem does not come from them because I listen mostly through headphones and often do transfers to PC for making car CDs, home DVD-As, etc. The hum is definitely there then even without the speakers.
Click to expand...
Is it a hum or a rumble? They're really two different sounds.
 
Maybe worth trying to put as much distance as possible between the amp & the TT & extend the phono cables .. about 8$
I always had a hum problem with a Thorens & when I set it up last week to try it out the problem had vanished .. it had been moved 5ft 1.5m away
 
Check out the samples I linked to at the beginning of the thread. It's a hum, but it only occurs when the needle is in physical contact with something, so it's not just typical grounding hum. It's physical/acoustic (but not speaker feedback since they are usually off).
 
That's weird. Everyone else has. Crank your system. It's there.

Anyway, I succeeded in reducing the hum by putting a solid wood cutting board I had between the tt and the shelf. This has reduced the sound substantially. It's still there but much more faint. So I guess my dealer was correct in his assumption about the resonance. Let me throw in a plug for Todd Saucier, the manager at Codell Audio here in Montreal. The guy really seems to know his turntables and seems willing to go the extra mile to make sure his customers are happy.
 
You must log in or register to reply here.
Back
Top Bottom