Turntable Noise

[oldmako]

Gents, I have vexing issue which I am sure you will be able to help with;

When I turn things UP....My TT sends a ton of noise to the amp. This obviously then gets sent to the speakers. It seems to me that it's caused by the cartridge picking up the ambient (loud) noise / vibrations created by the high volume of the music. It's starts out fairly quietly and increases in a linear fashion until I run over and turn the volume down. As soon as it's turned back up, the noise returns. It pretty much sucks.

The TT sits on a 1/2" thick slab of neoprene, and is on a shelf about chest high. My amp / preamp(s) / tuner combination sits on the shelf above the TT. The TT is approx 14 feet away from the speakers, and is not inline with the speakers. The TT is nothing special, a 30 year old Denon. It was about 200 bucks back then. Not radio shack junk, but not a sweet hi-end Thorens etc either. I would have thought that the neoprene would have prevented any bad vibes from coming up through the floor and infecting the sound in such a heinous manner.

The speakers (CF3s) sit on spikes on carpet, which is laid on a cement slab of a first floor, poorly constructed and hideously decorated condo. Two of my neighbors are hot, but I don't really think they have anything to do with this post.

More damping under the TT? Less volume is not an option on many of my old record albums.

[tidmack]

There will be others with tons more experience, but maybe a bad ground?

[Groomlakearea51]

Two of my neighbors are hot, but I don't really think they have anything to do with this post.

But.... purely for research purposes you should at least find out.... [6]

[LarryC]

Pics w/detail? It sounds like resonance to me, and neoprene seems more like insulation than NVH isolation. Is the TT non-suspended?

I suggest doing up one of those DIY isolation platforms, like tennis balls cut in half supporting a granite slab under the TT.

My isolation is more elaborate -- a Target wall-mount screwed into studs that rest on the foundation, and a Townshend air-bladder sink (no longer sold in the US). See if the slab/tennis ball approach works first.

[Guest davidness]

I know nothing, but I would try the following to garner more clues:

1) To see if 'the cartridge picking up noise' is the issue, remove the headshell from the arm and re-test.
2) Radically move the turntable to a different location, perhaps even behind a nearby doorway, isolating it from the room accoustics.
3) Rerun your signal & ground cables even though you're sure that isn't the problem, being certain to disconnect & reconnect all connectors.

Good luck.

[oldenough]

Pics w/detail? It sounds like resonance to me, and neoprene seems more like insulation than NVH isolation. Is the TT non-suspended?

I suggest doing up one of those DIY isolation platforms, like tennis balls cut in half supporting a granite slab under the TT.

My isolation is more elaborate -- a Target wall-mount screwed into studs that rest on the foundation, and a Townshend air-bladder sink (no longer sold in the US). See if the slab/tennis ball approach works first.

I go for the resonance thing as well....but can we get more info on the Hotties next door???....[]

[oldmako]

You guys are fabby. Many thanks for the replies and the help. First things firstest....

<<"But.... purely for research purposes you should at least find out.... ">> Found out I have (!) with one of the aforementioned hotties. A mere whisp of a lass, 5-5" or so and a just hair over 118 pounds. You'll just have to trust me when I say that each and every one of those pounds are in JUST the right spots. Some of them are very-very firm, while others impossibly soft. Dark hair and eyes...think of Gloria Trillo (Annabella Sciorra) the Mercedes Saleswoman on season 3 of the Sopranos. Neighbor hottie number one is just as fine as she was and is just as....well, do you remember the flying roast??

Number two has a live in BF who has an impressive and largely illegal collection of high powered semi and not so semi-automatic (as in fully automatic) firearms. She's tall and thin with an ever so small waist and long lovely limbs and lashes....auburn hair and auburner lips that tend to slowly part at the end of her smiles. She likes to twirl her hair as she talks and burns her Manson Lamps right through you. She's very touchy-feely ...as in the young blond pom-pom girl Angela Hayes (Mena Suvari) was while stroking Kevin Spaceys arm in American Beauty. "Gosh, have you been working out?" I stay pretty far away from her. I don't fear guns, just bullets.

WRT the TT......I'll try and post some pics when I return to my domo. I am on the road for the next two weeks.

I'll also double check the ground and connectors, and try to fabricate a more isolationist mount.

[HiFi Heaven]

Sounds like acoustic feedback. If it subsides when you go to MONO, that's your culprit. I've used pillows under the turntable in extreme cases.

Steve in Minneapolis

[neo33]

Do you have a spare bedroom you want to rent out?

<<"But.... purely for research purposes you should at least find out.... ">> Found out I have (!) with one of the aforementioned hotties. A mere whisp of a lass, 5-5" or so and a just hair over 118 pounds. You'll just have to trust me when I say that each and every one of those pounds are in JUST the right spots. Some of them are very-very firm, while others impossibly soft. Dark hair and eyes...think of Gloria Trillo (Annabella Sciorra) the Mercedes Saleswoman on season 3 of the Sopranos. Neighbor hottie number one is just as fine as she was and is just as....well, do you remember the flying roast??

Number two has a live in BF who has an impressive and largely illegal collection of high powered semi and not so semi-automatic (as in fully automatic) firearms. She's tall and thin with an ever so small waist and long lovely limbs and lashes....auburn hair and auburner lips that tend to slowly part at the end of her smiles. She likes to twirl her hair as she talks and burns her Manson Lamps right through you. She's very touchy-feely ...as in the young blond pom-pom girl Angela Hayes (Mena Suvari) was while stroking Kevin Spaceys arm in American Beauty. "Gosh, have you been working out?" I stay pretty far away from her. I don't fear guns, just bullets.

[WMcD]

This may need a more organized approach to trouble shooting.

1) What does the noise sound like? It it like white noise or pink noise (such as interstation hiss on a radio).

I'm thinking that if it is hiss, it has something to do with the phono section of the pre amp. Can you give us info on your amp. Can you borrow an amp to substitute in?

2) Is this physical and mechanical set up new? Did the set up ever work properly? What was the last thing which changed in your set up before this started.

3) I don't think it is feedback or a resonance. That would come on right away in milliseconds, rather than build up over seconds. It would not cause noise-hiss. None the less, you might try turning off the speakers and listen on headphones. That will rule out a feedback issue.

4) I doubt it is ground issue. Those usually cause 60 Hz or 120 Hz tones -- and they are immediate.

Wm McD

[TheEvan]

Gil, I took from his description that this only happens when he cranks the volume a good bit.The description sounds like feedback. Besides the isolation suggestions, I would think a rumble filter would help.

[kevinmi]

I have a little experience with older turntables. I would suggest this test first and foremost: turn on your turntable as if you were going to play an album, but don't lower the needle onto the record. With the tonearm suspended over the record, slowly turn up the volume to the point where you usually hear the noise. If the noise starts, you might be experiencing rumble coming from the motor, especially on a direct drive turntable, or from a bad bushing on a belt drive unit. If you get no noise, try this again with the needle on the record, but during a spot where there is no music playing, like at the end of the record. Turn up the volume again and see if you get noise. This will tell you whether the noise is coming from the turntable itself. If the noise only appears when music is playing, then you probably have a feedback type of problem. Using the HiFi News test record(or any other test record) is an excellent way of troubleshooting turntable problems, and will help take out the guesswork of finding your problem.

[oldmako]

I'll try and answer some of your questions to aid in the discussion.

a) Yes to the second room. $750/mo all utilils included unless you own a tanning bed, smelting oven, full size aircraft flight simulator, industrial tractor beam or 50 mile plus radar unit. If so, we'll have to work out something different on the electrics.

The TT is an old direct drive Denon. When I return home I will be able to provide the model number and run the suggested diagnostics.

c) I am using an old Phase Linear 400 amp, and a Pioneer SA9100 for my preamp. I was born a poor white child, sorry for the gear.

d) The noise is a type of hum.....not the same one I had before with the Phase 4000 preamp, this one is starts low and increases on a fairly straight line. The increase is fairly quick. The noise is only apparent when I am shoving copious watts into the speakers. I'm afraid that I have no ability to measure the decibels, but suffice it to say LOUD. Just imagine that you've got on The Who....."Behind Blue Eyes", or Los Lobos..."Don't Worry Baby"...or if hottie number one was over and in drinkin 'n' dancin' kind of mood..."Brick House". It sounds like the stylus is picking up the rooms vibrations (coming up through the cabinet?) and transmitting them to the amp.

I won't get back to my domo until next week at the earliest. At that time I'll try run some of the tests, and see if HN-1 is up for a few cold ones.

[TheEvan]

Feedback.

Make sure your preamp's rumble filter is ON. That will help. Isolation will help more. If your TT is located in a spot of the room that loads up with bass you may have to move your rig.

[WMcD]

Thank you, TheEvan, for the comment. I tend to agree with the isolation issue, particularly now that we know it is not noise-hiss.

I should probably pipe down because I've not fooled with a turntable in decades.

PWK had a take on isolation in the How to get best results from a K-Horn. IIRC he was adjusting the isolation system to that the resonance of the turntable base (and what it is attached to) has to be lowered down to single figures.

Wm McD

[oldmako]

Finally got home and ran a few tests as per some of your recommendations.

The noise is evident in either mono or stereo mode. Once the noise starts, it gets louder and the VU meters on my amp head east in a hurry. It would seem as though the cartridge is picking up the noise and sending an expoentially increasing signal to the preamp.

The noise is evident with the stylus in a no-sound portion of an album.

There is a fairly high noise threshold when the stylus is elevated in the lifted or qued position when the volume is turned up. This noise floor is not evident when in tuner, cd or aux.

[The Dude]

I like this thread it might be helpful to me as well.

duder

[LarryC]

it gets louder and the VU meters on my amp head east in a hurry. It would seem as though the cartridge is picking up the noise and sending an expoentially increasing signal to the preamp.

Pathognomic of feedback IMO. Got your tennis balls and granite slab ready to go?

[TheEvan]

Yeah, runaway feedback. It'll send you diving for your volume control every time.

You need more isolation, yeah. But your initial description of your setup and isolation tells me more may be in play. I wonder if your particular cartridge is prone to being microphonic...or to going microphonic with age.

[oldmako]

The TT and it's cartridge are at least 20 years old, perhaps more like 25. Coupled with the fact that it wasn't exactly a high dollar unit I suspect that I am going to have to get used to a bit of noise. This I can fix however. I just figured that a big slab of neoprene would be a good start.

I'll poke around for a hunk of granite. How about a racquetball sliced in half? I have tons of them.