Ediblehorse
Member
Thanks. The motor noise issue has been solved. It's the infamous Pro-Ject hum that I'm trying to get rid of.
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Pro-ject Debut Carbon upgraded to Ortofon Blue. Weird rumble sounds.
- Thread starter Ediblehorse
- Start date
Why would hum disappear when you hit the mono button?
Btw, motor noise and bearing rumble are two different things. I thought you cured the previous noise by oiling the bearing, or did I misunderstand that?
Ediblehorse
Member
You got me, but it goes away in mono.
Its been quite a trip. The motor noise was largely from the first defective stylus.
I lubed the spindle bearing and adjusted the motor mounting screws (had them completely out at one point, found the sweet spot.
I believe there's a wiring problem somewhere. Beyond my skill set. I'm gonna return the Blue and probably unload the TT.
Hum would be cancelled when you hit the mono button if the hum in the left channel was out of phase with the hum in the right channel. That's the clue to solving this problem in my opinion.
Ediblehorse
Member
I know nothing about electronics. What should I try now? I have a couple weeks before I give up and return Blue.
patient_ot
Super Member
Hum is a grounding issue. The grounding scheme on these turntables sucks, so you'll have to watch videos and experiment.
Could you explain to me how a grounding issue would produce hum which disappears in mono?
I suggest you leave the arm on the arm rest and listen for hum. Then switch the motor on and off to see if the hum depends on whether or not the motor is running.
Ediblehorse
Member
It is correct. Solid connections, correct positions.
patient_ot
Super Member
Missed that - probably something else then. OP should just unload this thing if they are not technically inclined and don't want to tinker.
Ediblehorse
Member
I will try this tomorrow. I have a feeling I may have been there at some point.
The hum starts when the stylus hits the vinyl.
I think....
Outta time tonight.
You are a night owl Rothwell?
Middle of night in UK?
Ediblehorse
Member
OP agrees.
How does a defective stylus turn a quiet motor into a noisy motor?
If that's the case, the stylus is definitely picking up vibrations through the platter, not picking up hum.
Yes, it's late and I'm just about to go to bed. Yes, I tend to be something of a night owl.
The symptoms (except for that odd "mono/stereo" hum issue) appears to be from a bad platter spindle/bearing. My Pro-ject was the same problem. I could actual feel the "rumble" when spinning the platter by hand. After removing the belt. The rumble varied feel and pitch with the speed at which you turned the freed platter. Does your turntable's noise sound different, at 45 RPMs, than 33?
I came to the conclusion a new and better bronze or maybe aftermarket sealed ball-bearing assembly would be needed to be pressed into the unit, to rid the turntable of the noise. This would be a complete DIY project (sorry about that pun).
I mic'ed the platter's spindle shaft OD. But, I gave that info to the guy at work, who got the unit --- for free. I couldn't really charge him, for a defective turntable. BTW... I bought the Pro-ject over-built PS hoping that that would reduce the background noise, as the turntable had hum on top of rumble. It didn't work, either.
The biggest reason for all of this attempts at fixing, is my old, old Sony 2251 is so quiet, that I nearly blast myself out of the room, when cranking the volume --- during dead blank vinyl sections --- to listen for any noise. So, I knew my AC line was clean (I have it connected to a mil spec Ultra-Isolation transformer). And I wasn't picking up any EMF junk from computers or cell phones. I could never get the Pro-ject to be quiet.
I came to the conclusion a new and better bronze or maybe aftermarket sealed ball-bearing assembly would be needed to be pressed into the unit, to rid the turntable of the noise. This would be a complete DIY project (sorry about that pun).
I mic'ed the platter's spindle shaft OD. But, I gave that info to the guy at work, who got the unit --- for free. I couldn't really charge him, for a defective turntable. BTW... I bought the Pro-ject over-built PS hoping that that would reduce the background noise, as the turntable had hum on top of rumble. It didn't work, either.
The biggest reason for all of this attempts at fixing, is my old, old Sony 2251 is so quiet, that I nearly blast myself out of the room, when cranking the volume --- during dead blank vinyl sections --- to listen for any noise. So, I knew my AC line was clean (I have it connected to a mil spec Ultra-Isolation transformer). And I wasn't picking up any EMF junk from computers or cell phones. I could never get the Pro-ject to be quiet.
Question: since the hun goes away in mono, and it only starts in stereo when the stylus touches the record, isn’t something in the signal path cancelling out that hum? More an more this sounds like a connection issue.
No. Vertical motion in a stereo cartridge produces out of phase signals in the left and right channels. Combining those signals into mono cause them to cancel.
Here's a description from the webpage for the KAB RF-1 subsonic filter:
https://www.kabusa.com/frameset.htm?/rf1.htm
The relevant bit says " When records are made, frequencies below about 150Hz are combined to mono. This is done to avoid large out of phase groove excursions. When the stereo stylus moves vertically, the two signals produced are equal and 180 degrees out of phase. Therefore, below 140Hz, the music is in phase in the lateral stylus motion, and only out of phase noise is found in the vertical stylus motion."
So, there's no "hum" when the stylus isn't on the record because there is no electrical or hum pickup problem. The "hum" is actually motor vibration which the stylus doesn't pick up until it touches the vinyl. When it does touch the vinyl the stylus goes up and down, which produces out of phase noise in the left and right channels. Hitting the mono button causes the out of phase noise to cancel.
Ediblehorse
Member
Okay, have no time to mess around with TT tonight.
However, something I overlooked which may be very important.
The RCA jacks going into the TT could certainly fit tighter.
I have tried 3 sets of various cables and all are sort of loose.
I'll put it this way. if I were to tug on the cables the Plugs would come out and the TT would not move a hair.
However, something I overlooked which may be very important.
The RCA jacks going into the TT could certainly fit tighter.
I have tried 3 sets of various cables and all are sort of loose.
I'll put it this way. if I were to tug on the cables the Plugs would come out and the TT would not move a hair.
That doesn’t sound good. Wish you luck.