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Topic: Permanent low rumble with Technics SL-1500c (Read 921 times) previous topic - next topic
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Permanent low rumble with Technics SL-1500c

Hello,

I would like some advice on how I could solve this. (And I'm rather new to this whole topic.)
I get a permanent low rumble when recording from Technics SL-1500c built-in preamp.
(If it was only for playback I wouldn't mind too much but my goal is to digitize some rare records as pristine as I can.)

I have two audio interfaces that I can use M-Audio Air 192|14 and Asus Xonar Essence STX, both record approximately the same thing.
I tried changing the RCA cable between Technics SL-1500c and audio interfaces...
I do not have another phono preamp, I bought this record player consider availability in my country and all the praises I read about its built-in preamp so it's not my plan to by an additional one.

Here is a Soundcloud play list of the sounds (download is activated)
Permanent Rumble from Technics SL-1500c : https://soundcloud.com/user-313287047-284149275/sets/permanent-rumble-from-technics-sl-1500c/s-yhaRbYFZ0Gy
Track 1: Rumble as it was recorded through M-Audio Air 192|14 Line In (7/8) on 23/03/2021.
Track 2: Rumble as it was recorded through M-Audio Air 192|14 Line In (7/8) on 23/03/2021, amplified by 40dB.
Track 3: Rumble as it was recorded through M-Audio Air 192|14 Line In (7/8) on 02/04/2021, after turning off even more devices including ceiling light amplified by 40dB.
Track 4 : Rumble as it was recorded through M-Audio Air 192|14 Line In (7/8) on 02/04/2021, after bringing power from a room at other side of apartment with a very long power cable..

SOME OBSERVATIONS:
Repeated clicking/rumble, very low, I needed to add like 20 dB to hear it (but I can hear it in very quiet parts of the music if I pay close attention).

Present as soon as M-Audio Air 192|14 Line In (7/8) is connected to Technics SL-1500c phono pre-amp.
Present as soon as Asus Xonar Essence STX Line In is connected to Technics SL-1500c phono pre-amp.

Happens independently from M-Audio inputs, tried mostly with Line In 1/2 and Line In 7/8.

Happens even when Technics SL-1500c is turned off, and/or phono pre-amp is turned off.
Happens when Technics SL-1500c is plugged directly to power strip (even if 1500c is off and power strip is turn off by its switch).
Happens when Technics SL-1500c is plugged directly to the wall (even if 1500c is off).
Disappears only if Technics SL-1500c is completely unplugged from power.

Since I use the built-in preamp, phono ground is not connected to anything.

Technics SL-1500c is plug directly to the wall. M-Audio Air 192|14 Line In is alone on a power stripe. (and I tried switching them)
Computer is on a distinct power stripe that is approximately 2 meters away from the M-Audio + Technics installation.

On some tests with Xonar Essence STX, it seemed like the clicking was not there when I just connected things and had not turned Technics SL-1500c on yet. But after it's been turned on, then I did some tests, then I turned it off and did some tests again. Clicking is there again. So I guess it may be something that accumulates or is trigger by some event when or after turning SL-1500c on.

I tried turning off some devices, but obviously can turn every single device off (primarily, I need the computer on to record sound).
2/4/2021: I tried turning off even more devices including ceiling lights. I think I noticed so change in the rumble, but it's still very present.

Obviously, I cannot turn off my computer otherwise I can't record or hear anything. Computer case is approximately 1 meter away from M-Audio + Technics , but since its power supply is at the back it's more like 1.5 meter away.
- Something I'm thinking right now is fetch a very long power cable (one for gardening actually) to bring power to Technics SL-1500c from a completely different room, one where there are no computers...

Thank you for your help.

Re: Permanent low rumble with Technics SL-1500c

Reply #1
Quote
Repeated clicking/rumble, very low, I needed to add like 20 dB to hear it (but I can hear it in very quiet parts of the music if I pay close attention).
It's an analog record!  ;)   Some hiss & hum from the preamp is normal, as is some "mechanical" rumble picked-up through the stylus.    You won't get mechanical rumble if the motor isn't running and usually the rumble is subsonic and it can be removed with a 20 or 30Hz high-pass filter.  The worst noise is usually from the record itself.

But, the clicking/cycling several times per second is WEIRD!   It might interference picked-up through a ground loop, since you're still getting it with the preamp turned off.   Do you have one of those adapters that can break the power-line ground to the turntable?    (That's a safety ground in case there is a power-line short to the chassis so you're not supposed to do that.)



Re: Permanent low rumble with Technics SL-1500c

Reply #2
This noise is without anything at work on the record player, not turning, no record, just standing still.

Quote
Do you have one of those adapters that can break the power-line ground to the turntable?    (That's a safety ground in case there is a power-line short to the chassis so you're not supposed to do that.)

Sorry, I don't understand this one ... English is not my mother language, I usually understand it fairly well but I can't figure this part of the sentence "break the power-line ground to the turntable"...

Do you mean like power strips that have safe breaks in case there's too much power in them ? yeah, I have those on computers, but even if I plug the record player directly to the wall, I still get the rumble/clicking/pulse... (But I'm not sure at all if this is what you meant.)

Re: Permanent low rumble with Technics SL-1500c

Reply #3
I just realise that I should posted this in the "Vinyl" forum, maybe I will ask someone if they can move it there...

Re: Permanent low rumble with Technics SL-1500c

Reply #4
I may have identified something significant (for my search) ...

I installed the M-Audio drivers and Audacity on a laptop and made new tests, pulse was gone. (I did not even turn my main computer off, nor the ceiling lights.)
I need to make more tests because this may still be a false positive (maybe disturbance came from someone else's apartment and they're not active right now or so) ... yet the laptop is not my own laptop, ... I need to do more tests on my own computers...
But what was different in the test:
- The whole computer
- Using Audacity instead of Sound Forge Pro (edit: Tested with Audacity on my main computer, got pulse, so it's by the way not Sound Forge Pro that is at fault.)

But it's still really confusing because my main computer is able to record with no pulse when the record player is out of the chain...

 

Re: Permanent low rumble with Technics SL-1500c

Reply #5
Now tried on the back USB of my main computer (it's a big tower case and I was previously using the front USBs just because they are easier to reach.)
Rumble is almost unnoticeable ... I can still guess that it is there, but it's almost hidden in the "minimal" background noise. And I need to amplified the whole thing by 20 to 40 dB... (Yet like a big half of it seem to get removed by various "de-noising" plug-ins.)
But overall, I get less background noise on the laptop, a bit surprised since in both cases I used the same M-Audio interface.


Re: Permanent low rumble with Technics SL-1500c

Reply #7
Have you checked the grounding?
https://www.amazon.com/Electrical-Receptacle-Outlet-Ground-Tester/dp/B0012DHVQ0

I guess I should buy one of these ... Didn't know those existed and they could be so cheap ...

But recently some electrician told my mom that her house was not connect to ground at all... But previous electrician said he had done it ... I don't live there so what the electrician said to my mom is irrelevant for my record player problem ... but I got convinced that tools to fact-check what electricians say may be useful...

Re: Permanent low rumble with Technics SL-1500c

Reply #8
Have you checked the grounding?
https://www.amazon.com/Electrical-Receptacle-Outlet-Ground-Tester/dp/B0012DHVQ0
That's a great and handy tool to have.

I guess I should buy one of these ... Didn't know those existed and they could be so cheap ...

But recently some electrician told my mom that her house was not connect to ground at all... But previous electrician said he had done it ... I don't live there so what the electrician said to my mom is irrelevant for my record player problem ... but I got convinced that tools to fact-check what electricians say may be useful...
It's with anybody that you hire to come do work on your home or any property you own.  You got to be careful.  Electrical problems can lead to big problems like fires or someone getting killed if it doesn't done correctly.  Electrical is surprisingly a lot simpler than what most people would think.


Re: Permanent low rumble with Technics SL-1500c

Reply #10
I doubt so because turntable is NOT playing when I record the pulse. The same pulse is still present when turntable is playing but it's not triggered when playing.

Also I think that Technics SL-1500c feet already had some vibration absorbing parts.

Re: Permanent low rumble with Technics SL-1500c

Reply #11
I'd sat it's periodic, so it's likely that it's electrical interference from something.

Re: Permanent low rumble with Technics SL-1500c

Reply #12
Most recent test I did was to try on the rare USB 3 of my main computer, instead of front USB. And the pulse was not there.

So it looks like it's a USB port issue.
I'm a bit surprised since I though all USB port being digital, they would simply work or not work, but the sound is different.
I'm also confused because at the other end of the chain, bringing electrical power from another room had actually decreased pulse intensity.

Re: Permanent low rumble with Technics SL-1500c

Reply #13
I'm a bit surprised since I though all USB port being digital, they would simply work or not work, but the sound is different.

Not so strange. Imagine you and I are sitting on a telephone line communicating "digitally" as follows: I am simply reading aloud "zero, one, one, one, one, zero, one, zero, zero, zero, ..." and you are typing it. That is binary digital communication over ... over what? Possibly over analogue telephone, but it doesn't even matter whether it is over analogue or digital telephone. Also a bit of hum would be tolerable for the binary digital transmission. Even annoying (to us!) levels of hum would be fine to the bits.
High Voltage socket-nose-avatar

Re: Permanent low rumble with Technics SL-1500c

Reply #14
Quote
Now tried on the back USB of my main computer (it's a big tower case
Since you have a tower computer I assume you have a regular soundcard (or soundchip built into the motherboard).   The the line-input on your soundcard (usually color-coded blue) is worth a try.    Your M-Audio interface should  be "better", but maybe not in this case.

Quote
So it looks like it's a USB port issue.
I'm a bit surprised since I though all USB port being digital, they would simply work or not work, but the sound is different.
The 5V USB power is often noisy and that power supply noise can  get into the analog circuitry inside the interface.    It's actually a fairly common problem, but the noise is usually amplified in the preamp, and you're using the preamp in your turntable.    And, it's usually a high-pitch whine, and I don't think your M-Audio interface is USB powered...

It could still be some kind of grounding issue, but it's noise getting in on the analog-side of the interface, not the digital-USB side.

Quote
Sorry, I don't understand this one ... English is not my mother language, I usually understand it fairly well but I can't figure this part of the sentence "break the power-line ground to the turntable"...
In the U.S. it looks like this.  It's really not designed to break the ground.   Some older houses have 2-prong outlets and a tool or appliance with a 3-prong grounded plug won't plug-in.     The adapter is supposed to  make the ground connection through the cover-plate screw, since the electrical box is supposed to be grounded.


Re: Permanent low rumble with Technics SL-1500c

Reply #15
Since you have a tower computer I assume you have a regular soundcard (or soundchip built into the motherboard).   The the line-input on your soundcard (usually color-coded blue) is worth a try.    Your M-Audio interface should  be "better", but maybe not in this case.

As mention in the (long) initial post, inside the computer I have:
- Asus Xonar Essence STX, which was marketed as an "audiophile" soundcard and should perform close to the M-Audio interface, though limited to 96 kHZ and not 192 kHz (though some reviews report some flaws in it frequency response or so, I don't remember precisely, it's still quite good).
- Motherboard built-in Realtek something sound card, which I don't know any detail about but it usually sounds good.

And I did some tests in the beginning with the Asus Xonar and I could hear the pulse, in more recent tests I could not hear the pulse there anymore so I'm juste confused about this ...

Haven't tried with the Realtek card.

The 5V USB power is often noisy (...)

I actually have no idea what USBs are actually 5V or so... I guess I should check the manual ... But yet I know that my front USBs don't necessarily match any documentation because they were simply connected to anything that was available on the motherboard. (Not all computer cases has so many front connexions...)

Actually here is what I now get front rear USB: https://soundcloud.com/user-313287047-284149275/is-this-good-after-moving-to-read-usb-30-tv-over-power-is-back-40db

It's amplified by 40dB. Do it sound good ?


Quote
It could still be some kind of grounding issue, but it's noise getting in on the analog-side of the interface, not the digital-USB side.

My first guess was something wrong with the computer impacting power which would be impacting the record player in some kind of loop... I ordered a tool to test grounding (more or less like the one linked above), but even with that I'm not sure if I'll be able to do much.

Regarding the last part, I'm still not sure if I understand, because I guess I don't really know what it is, I guess I don't have those.
Building is old, but power in the apartment has been modernised 15 years ago ... but as mentioned earlier, I never really know how far I can trust electricians, some electrician told me more recently that he didn't like the plug that the previous electrician had installed in the bathroom...
But what I have is more like lightning protections like this: https://thumbs.static-thomann.de/thumb/orig/pics/bdb/506839/15742026_800.webp
Some are on blocks like this, some are on power strips. (And they are random mixed brands, though one of my power strip is of that brand.)



Re: Permanent low rumble with Technics SL-1500c

Reply #16
So regarding previous discussion in this topic, I bought


The result I get is all red lights and no lightning warning sign. Which according to the device means
"L<>N & notN"

But, I'm in Belgium and I read someone on the Internet complaining the "in 202x something, Belgium still doesn't have neutral !"

I seriously won't have time to even try to understand this formula and this sentence mean for weeks or months...
So if some who understand can explain it in a simple way that would be nice ;-)

(Tried at my mom's place, got the same result.)

 
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