Turntable feedback from nearby speaker

[captainvi...@gmail.com]

I've just gotten finished, (or so I thought) upgrading and servicing all the equipment in my entertainment center. I just replaced my mediocre speakers with a pair of nice 12 inch JBL's that were abandoned in the building we just bought. My turntable is an old Thorens belt drive, supported with a spring arrangement that I thought would absorb any vibration. The turntable is in a cabinet about a foot off the floor and right next to the left channel speaker. If I crank up the volume when listening to a record there is distortion, the severity directly proportional to the increase in volume. At first I wasn't certain about this but you can actually "feel" the vibrations on the turntable base. There are these springs supporting the platter and arm and these springs are "stuffed" with a foam material but this vibration is coming through anyway. I know that one solution is to relocate the speaker however the room is not large enough to do this. I was thinking of putting foam under the speaker which would be easy and perhaps even a soft foam block under the turntable as well but I'm afraid that trying to support and level a turntable supported like this could be a nightmare. Does anyone have any ideas? Thanks, Lenny

[Phil Allison]

<captainvi...@gmail.com>

>There are these springs supporting the platter and arm and these springs
>are "stuffed" with a foam material

** Remove the foam.

> I was thinking of putting foam under the speaker

** Waste of effort.

> The low frequency vibrations are transmitted through the air, shaking the
> floor, walls and ceiling.


.... Phil

[captainvi...@gmail.com]

On Wednesday, December 18, 2013 8:10:39 PM UTC-5, captainvi...@gmail.com wrote:
> I've just gotten finished, (or so I thought) upgrading and servicing all the equipment in my entertainment center. I just replaced my mediocre speakers with a pair of nice 12 inch JBL's that were abandoned in the building we just bought. My turntable is an old Thorens belt drive, supported with a spring arrangement that I thought would absorb any vibration. The turntable is in a cabinet about a foot off the floor and right next to the left channel speaker. If I crank up the volume when listening to a record there is distortion, the severity directly proportional to the increase in volume. At first I wasn't certain about this but you can actually "feel" the vibrations on the turntable base. There are these springs supporting the platter and arm and these springs are "stuffed" with a foam material but this vibration is coming through anyway. I know that one solution is to relocate the speaker however the room is not large enough to do this. I was thinking of putting foam under the speaker which would be easy and perhaps even a soft foam block under the turntable as well but I'm afraid that trying to support and level a turntable supported like this could be a nightmare. Does anyone have any ideas? Thanks, Lenny

I'll try removing the spring foam and see what happens. Thanks, Lenny

[David Platt]

> I was thinking of putting foam
>under the speaker which would be easy and perhaps even a soft foam block
>under the turntable as well but I'm afraid that trying to support and
>level a turntable supported like this could be a nightmare. Does anyone
>have any ideas? Thanks, Lenny

One approach I've seen used is to add both mass, and decoupling, to
the turntable.

Mass: go buy a sheet of rock. Stone. Cement. Something like that.
If you want to be elegant, go to a stonecutter, pick out a piece of
marble or limestone or granite whose color appeals to you, and have a
slice cut and polished which is just the size of your turntable base.
If you're on a budget and don't care terribly about looks, get thee
hence to a home-improvement/garden store and buy a concrete or brick
"paver" roughly the size of your turntable base (18"x18" is a good
size to look for). All else being equal, thicker is better than
thinner.

Decoupling: go to a bicycle store, and buy a small-diameter heavy-duty
bicycle inner tube. If you bought an 18"x18" paver or marble slab, a
16" inner tube would be a good size to try. You want it to be just a
bit smaller in diameter than the smaller side of the stone slab, so
that the slab will sit on it in a stable position without the tube
"bulging out" in any direction.

Partially inflate the inner tube. Lift your turntable out of position
(unplug first, of course). Put the partially-inflated inner tube in
its place. Put the stone slab on top of the inner tube, and put the
turntable on the stone. If it doesn't sit entirely level, lift the
turntable and slab and try moving an inch or so in each direction to
get it to level out.

If the weight of the slab makes the cabinet collapse and dump your
turntable onto the floor... oops :-( Sorry about that.

This approach will greatly reduce the amount of structure-borne
vibration which gets up to your turntable through the cabinet or
shelf.

It won't do anything much to reduce airborne vibrations (acoustic
pickup). Removing the dust cover entirely when you're playing music
can help to some extent.

A somewhat similar approach involves building a heavy platform for the
turntable to sit on, and suspending it from above using rather long
springs.

In either case, you want the resonant frequency of the mass/spring
system (whether it's a metal spring, or the "air spring" of an inner
tube) to fall below the lowest bass frequency from the speakers. This
creates a "low pass" filter which will tend to attenuate the bass
before it feeds back into the turntable system. It's also good if it
falls below the resonant frequency of the arm/cartridge system, so
that the two resonances don't reinforce one another and cause
excessive stylus "wobble". If you can get it to the point where it
"bounces" 2-3 times per second and no faster, it should help stabilize
the turntable's playback quite a bit.

[jurb...@gmail.com]

HEY ! Try reversing the phase of the speakers. I shit you not. that howl is the same as what you would get out of a microphone.

One phase of the speakers (ALL OF THEM) will result in less acoustic feedback than the othsr.

Also, get the thing off the op of it. Thsat cover. It is a reflector and amp;lifier of feedback. (sound)

[isw]

In article <527518ff-54ad-43e6...@googlegroups.com>,

You're probably not going to like this, but the easiest -- and maybe the
best -- solution is to digitize the records and play the resulting
files. No acoustical feedback. No (more) degradation from the stylus
damaging the groove, either.

Years ago,when I still used vinyl records, I became concerned about the
exact same phenomenon, but when it was at a level where it couldn't be
*overtly* heard, but still was causing a modification of the desired
output signal. I figured that it just had to be there and I wanted to
measure it.

I came up with a scheme for placing a second cartridge on the record
that rotated with it, and taking the output of that as the signal to be
measured. Not only would it detect the acoustical feedback from the
speakers, but also the direct vibrations of the active stylus in the
groove, which has to be creating stuff that bounces off the edges of the
disc and back to the stylus as distortion.

Then CDs came along, and I totally lost interest in the whole project.

Isaac

[gregz]

Is the cabinet vibrating ? Putting the turntable further away ?

Greg

[Phil Allison]

<jurb...@gmail.com>

= Raving Nut Case

> HEY ! Try reversing the phase of the speakers.

** ROTFLOMAO !!!!!!!!!


> I shit you not.

** You shit folk - big time.

> that howl is the same as what you would get out of a microphone.

** Not it isn't.

> One phase of the speakers (ALL OF THEM) will result in less acoustic
> feedback than the othsr.

** Sure - put the stereo pair out of phase.

Brilliant solution.

Wot an IDIOT !!!!



.... Phil

[jurb...@gmail.com]

>"** Sure - put the stereo pair out of phase. "

That is NOT what I said !

Reverse the phase of ALL the speakers, then they wind in phase with each other but in the oposite phase regarding the phono cartridge.

I've done this a whole bunch of times and sometimes it does have a quite significant effect. The problem is that it's a 50/50 chance that it could get worse. In that case reverse them all back.

Concievably you could accomplish the same thing buy reversing both channels of the cartridge itself, but it is not designed for that. Some of them automatically ground the shell to one of the - terinals. Even if not it still kinda beelongs one way.

Ergo, you reverse the phase of the speakers. All of them. Unnastan now kid ?

[William Sommerwerck]

wrote in message news:527518ff-54ad-43e6...@googlegroups.com...

> The turntable is in a cabinet about a foot off the floor
> and right next to the left channel speaker.

I'm reminded of the old joke where a patient tells his doctor that his arm
hurts when he holds it vertically. "Then don't do that!"

I remember when H H Scott made console phonographs. They went through quite
some trouble preventing feedback when the turntable was in the same cabinet as
the speakers. And I doubt their speakers went as low as the JBLs.

Some of the suggestions are good (such putting a huge chunk o' granite under
the 'table), but you really need to move the turntable away from the
speakers -- and the walls.

[jimmy mac]

In article <t02aoa-...@coop.radagast.org>,

Thanks for some good advice!

--
jimmymac

spell usenet backward for email

[dave]

Why not just fly the speakers?

[Gareth Magennis]

wrote in message
news:527518ff-54ad-43e6...@googlegroups.com...

It's been common practice for decades now in nightclubs, to sit the Technics
1210 turntables on a heavy slab of whatever material is available, to reduce
such feedback from large PA systems in close proximity.

I think Jurb's advice is well worth trying. You might find the turntable
is currently in one of the room's many resonant bass peaks, and reversing
overall phase might put it in a trough.
Or you could move the turntable and speakers as much as is possible to try
and get them out of this peak, perhaps reversing phase as well to see what
works best.

As Jurb implies, it is always possible you are in a trough already, and
anything you try could make things worse, but that would be the absolute
worst case scenario.



Gareth.

[Phil Allison]

"dave"

>
> Why not just fly the speakers?

** ROTFL

High time for you to FLY - fuckwit.




.... Phil

[Phil Allison]

<jurb...@gmail.com>

>>
> >"** Sure - put the stereo pair out of phase. "
>
> That is NOT what I said !

** You should have - cos that at least has a chance of working.

>
> Reverse the phase of ALL the speakers,

** Makes no difference at all.

I've done this a whole bunch of times and sometimes it does have a quite
significant effect.

** Makes no difference at all.

The problem is that it's a 50/50 chance that it could get worse.

** Makes no difference at all.

> Ergo, you reverse the phase of the speakers. All of them.

** Makes no difference at all.

Dickhead.


.... Phil


Unnastan now kid ?
>
>
>

[Boris Mohar]

On Thu, 19 Dec 2013 11:12:20 -0700, jimmy mac <use...@fastmail.fm> wrote:

>> the turntable's playback quite a bit.
>
>Thanks for some good advice!

For a real torture test play Dark Site of the Moon.

--
Boris

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com

[jurb...@gmail.com]

>"* Makes no difference at all."

How could you claim to be any kind of engineer and say that ?

OK supposedly smart fuck, design an oscillator with negative feedback instead of postitive and see how far you get.

Anyway, whoever mentioned the turntable havinmg isolation, I had this Dual 1229 for a while that you could pretty much just sit right on top of the speaker. And I did. And my speakers always have bass. If it ain't got bass out the fucking door it goes.

[Leif Neland]

Efter mange tanker skrev jurb...@gmail.com:

>> "* Makes no difference at all."
>
> How could you claim to be any kind of engineer and say that ?
>
> OK supposedly smart fuck, design an oscillator with negative feedback instead
> of postitive and see how far you get.
>

You have to take into account the speed of sound and the distance
between speaker and pickup.

It does not matter if the speaker is in phase or not, it matters what
the phase of the soundwave when it hits the record a little later.

Leif

--
Husk kￜrelys bagpￜ, hvis din bilfabrikant har taget den idiotiske
beslutning at undlade det.

[Michael A. Terrell]

Boris Mohar wrote:
>
> On Thu, 19 Dec 2013 11:12:20 -0700, jimmy mac <use...@fastmail.fm> wrote:
>
> >> the turntable's playback quite a bit.
> >
> >Thanks for some good advice!
>
> For a real torture test play Dark Site of the Moon.

Take plenty of oxygen with you. ;-)


--
Anyone wanting to run for any political office in the US should have to
have a DD214, and a honorable discharge.

[Phil Allison]

"Leif Neland"

>
>>> "* Makes no difference at all."
>>
>> How could you claim to be any kind of engineer and say that ?
>> OK supposedly smart fuck, design an oscillator with negative feedback
>> instead of postitive and see how far you get.
> You have to take into account the speed of sound and the distance between
> speaker and pickup.
>
> It does not matter if the speaker is in phase or not, it matters what the
> phase of the soundwave when it hits the record a little later.
>

** If low frequency sound waves were vibrating the LP direct - there would
be no fix other than removing the TT from the room. So this is not the usual
case.

Turntable feedback IS a result of the room's *structure* vibrating in
sympathy with standing waves at particular
wavelengths - mainly the floor if the TT is supported by that OR the walls
if a shelf is being used. The frequencies of such standing waves depend on
the room's dimensions and the speed of sound.

Any TT must be isolated from these vibrations and the oldest and by far most
effective way is by use of coil spring.

IME, the ideal set up is 3 conical springs and enough weight above them to
result in vertical oscillation at about 2 Hz. When displaced, the TT system
should move freely and oscillate up and down for a couple of seconds - so
any connecting cables must be looped and able to follow the movement easily.
No damping material should be used.

If done correctly, room surface vibrations no longer affect the TT - even
jumping on the floor - so the chance of actual feedback is eliminated.


... Phil

[jurb...@gmail.com]

>It does not matter if the speaker is in phase or not, it matters what
the phase of the soundwave when it hits the record a little later. "

Of course it does. That is why there is a difference.

In a given installation the way the timing is and the most prevalent feedback frequencies could result in it resonating at say, 3Khz, which is not so hard to deal with. In the opposite phase it may resonate at 65 Hz, which is ALOT harder to deal with.

Been there done that. thisis why I took the opportunity to stick it up Allison's ass, just because. Because he loves to do it to other people.

I am still waiting for the oscillarot with negative instead of positive feedback. I got all the reponse of an Israeli government official when asked about the kill ratio on the Palestinians.

Motherfuckers spout shit out, and then can't even come bvack and say they were wrong with dignity. They hide. Fukum.

Fuck all this. It's too nice a day.

I have PERSONAL EXPERIENCE THAT IT DOES MAKE A DIFFERENCE, and that Turet's Symdrome motherfucker can either come out and say he was wrong or make moreof an ass out of himself trying to insult me, which is impossible because unless I have respect for the insulter, I have no respect for the insult.

[captainvi...@gmail.com]

On Wednesday, December 18, 2013 8:10:39 PM UTC-5, captainvi...@gmail.com wrote:

> I've just gotten finished, (or so I thought) upgrading and servicing all the equipment in my entertainment center. I just replaced my mediocre speakers with a pair of nice 12 inch JBL's that were abandoned in the building we just bought. My turntable is an old Thorens belt drive, supported with a spring arrangement that I thought would absorb any vibration. The turntable is in a cabinet about a foot off the floor and right next to the left channel speaker. If I crank up the volume when listening to a record there is distortion, the severity directly proportional to the increase in volume. At first I wasn't certain about this but you can actually "feel" the vibrations on the turntable base. There are these springs supporting the platter and arm and these springs are "stuffed" with a foam material but this vibration is coming through anyway. I know that one solution is to relocate the speaker however the room is not large enough to do this. I was thinking of putting foam under the speaker which would be easy and perhaps even a soft foam block under the turntable as well but I'm afraid that trying to support and level a turntable supported like this could be a nightmare. Does anyone have any ideas? Thanks, Lenny

I have a question for Phil. As I had mentioned earlier there are soft foam rubber inserts inside the three coil suspension springs on my turntable. You had mentioned to remove these. I am going to try that but haven't had a chance to try this yet, but why did they put that foam in there in the first place? Lenny

[jurb...@gmail.com]

Why Phil ?

/the spongie things are to keep the coils of the spring from resonating, remember resonance ?

[jurb...@gmail.com]

BTW, removing the foam is not a good idea.

[William Sommerwerck]

wrote in message news:82eef806-249d-47b4...@googlegroups.com...

> BTW, removing the foam is not a good idea.

Correct. It provides damping.

[Phil Allison]

"William Sommerwanker = Fuckwit Idiot "

>> BTW, removing the foam is not a good idea.
>
> Correct. It provides damping.

** Which is not wanted in this case.

FOAD you stinking moron.

[amdx]

On 12/19/2013 9:54 AM, William Sommerwerck wrote:
> wrote in message
> news:527518ff-54ad-43e6...@googlegroups.com...
>
>> The turntable is in a cabinet about a foot off the floor
>> and right next to the left channel speaker.
>
> I'm reminded of the old joke

Well, if you're going to go there,
He needs some noise cancelling speakers, that cancel
at the turntable.
Mikek

[dave]

Why not fly the speakers? If you can't fly the speakers, why not fly the
turntable? What is the construction of the room? Slab? Wood over crawl
space? Is there foot traffic above? Can't fly the turntable. You want
the speakers somewhere other than the same floor as the turntables. Did
you try the "rumble" (infrasonic) filter? Did you try swapping left with
right at the TT preamp?

[Phil Allison]

"dave"

>
>
> Why not fly the speakers?

** IT MAKES NO DIFFERENCE !!




... Phil

[William Sommerwerck]

I have one of the following. In fact I suggested the name to the manufacturer
(or encouraged him to keep the name, I forget which).

http://www.head-fi.org/t/408141/sold-arcici-lead-balloon-turntable-stand-rare

https://www.google.com/search?q=lead+balloon+turntable+stand&rlz=1T4NDKB_enUS510US510&tbm=isch&tbo=u&source=univ&sa=X&ei=u0fBUravDpPjoATFt4LABA&ved=0CFYQsAQ&biw=1607&bih=1060

It sits next to the left-rear speaker, and I have no problems.
(Qualification... My speakers are planar dipoles, and the stand is not far
from the lateral null.)

[dave]

How many discoteques have you built, Phil?

[Phil Allison]

"dave"

Phil Allison wrote:
>> "dave"
>>>
>>>
>>> Why not fly the speakers?
>>
>> ** IT MAKES NO DIFFERENCE !!
>>

>>

> How many discoteques have you built, Phil?

** I used to build custom disco consoles for a living and designed and
prototyped a disco mixer that went into production.

For a long time, most of my customers were in the disco hire business, now
only few are.

But there is not much similarity between disco and home stereo systems -
which I have huge experience with.

And YOU seem to have no experience or knowledge of either.

So go fuck yourself - cunthead.



.... Phil

[Maynard A. Philbrook Jr.]

In article <bief0h...@mid.individual.net>, phi...@tpg.com.au says...

Yeah, what Phil says, pubic hair!

Jamie

[gregz]

You seem to be assuming mechanical vibration through mass is the problem,
and not the air vibration.

Greg

[dave]

He says to the man who for years would seek out a living room with a
concrete floor so I can play my vinyl louder.

Decoupling the speaker from the phono cartridge at the natural resonant
frequency of the system is essential. Usually this frequency is lower
than the LF cutoff off the transducer/cabinet making sound so the LF
feedback transmission mode is through objects more solid than air. If
both speakers and TT are on a giant cement slab with great mass, nothing
vibrates except the speaker cones in the air and the stylus.

If the floor is wood over joists the room turns into a giant sounding
board. Vibrations from the speakers easily overcome the damping
mechanism in the turntable and the speaker cones start flapping in
unnatural efforts to reproduce the infrasonic.

I have never turned up the gain enough to make the stylus feedback in
free air; it is almost always a mechanical path. Speaker to floor. Floor
to turntable. Floors also couple to walls, walls to the ceiling; but
there is enough attenuation in this mechanical path to allow the damping
in the turntable base to take care of the residual vibrations.

You can hang the speakers (I have flown many L-100, Century 100, etc.
JBL monitors in just this fashion) or you can hang the turntable (weird,
but very doable and a must in houses where people walking can make the
needle jump.)

In commercial applications too numerous to mention I have left a trail
of weird fixes (and several tons of bagged Redy-Mix concrete) in my wake.

Now, being the "cunt head" that I am, off to go fuck myself. You should too.

[Phil Allison]

"dave the fuckwit troll"

** You are a complete fool and a damn liar - dave.

> He says to the man who for years would seek out a living room with a
> concrete floor so I can play my vinyl louder.

** Lie #1

Rooms with concrete floors can still have BIG problems with TT feedback at
low frequencies.

> Decoupling the speaker from the phono cartridge at the natural resonant
> frequency of the system is essential. Usually this frequency is lower
> than the LF cutoff off the transducer/cabinet making sound so the LF
> feedback transmission mode is through objects more solid than air. If both
> speakers and TT are on a giant cement slab with great mass, nothing
> vibrates except the speaker cones in the air and the stylus.

** Total pack of stupid lies.

> If the floor is wood over joists the room turns into a giant sounding
> board. Vibrations from the speakers easily overcome the damping mechanism
> in the turntable and the speaker cones start flapping in unnatural efforts
> to reproduce the infrasonic.

** More stupid lies.

TT feedback is not subsonic, it is audio frequency and is due to sound
pressure induced vibrations in the room's structure.

> I have never turned up the gain enough to make the stylus feedback in free
> air;

** HUH ???

Not even resting on the record?

> it is almost always a mechanical path. Speaker to floor. Floor to
> turntable. Floors also couple to walls, walls to the ceiling; but there is
> enough attenuation in this mechanical path to allow the damping in the
> turntable base to take care of the residual vibrations.

** More total crap.


> You can hang the speakers ....

** Has no effect on TT feedback - you lying asshole.

> In commercial applications too numerous to mention I have left a trail of
> weird fixes (and several tons of bagged Redy-Mix concrete) in my wake.

** And all along, the only thing that was ever needed was a few coil springs
under the TT. .

> Now, being the "cunt head" that I am, off to go fuck myself.

** ROTFL !!

You have been totally FUCKED for the whole of you miserable life - asshole
.

Cos you were a genetic mental retard from birth.



.... Phil

[dave]

Not with a Pair of L-100s

[dave]

On 01/01/2014 02:36 PM, Phil Allison wrote:

> "dave the fuckwit troll"
>
> ** You are a complete fool and a damn liar - dave.
>
>> He says to the man who for years would seek out a living room with a
>> concrete floor so I can play my vinyl louder.
>
> ** Lie #1
>
> Rooms with concrete floors can still have BIG problems with TT feedback at
> low frequencies.
>
>
>> Decoupling the speaker from the phono cartridge at the natural resonant
>> frequency of the system is essential. Usually this frequency is lower
>> than the LF cutoff off the transducer/cabinet making sound so the LF
>> feedback transmission mode is through objects more solid than air. If both
>> speakers and TT are on a giant cement slab with great mass, nothing
>> vibrates except the speaker cones in the air and the stylus.
>
> ** Total pack of stupid lies.
>
>
>> If the floor is wood over joists the room turns into a giant sounding
>> board. Vibrations from the speakers easily overcome the damping mechanism
>> in the turntable and the speaker cones start flapping in unnatural efforts
>> to reproduce the infrasonic.
>
> ** More stupid lies.
>
> TT feedback is not subsonic, it is audio frequency and is due to sound
> pressure induced vibrations in the room's structure.

How does the vibration get from the structure to the cantilever?

>
>
>> I have never turned up the gain enough to make the stylus feedback in free
>> air;
>
> ** HUH ???
>
> Not even resting on the record?

Not with JBL L-100s

>> it is almost always a mechanical path. Speaker to floor. Floor to
>> turntable. Floors also couple to walls, walls to the ceiling; but there is
>> enough attenuation in this mechanical path to allow the damping in the
>> turntable base to take care of the residual vibrations.
>
> ** More total crap.

If you look at attenuation in free air v attenuation of dry building
materials youd see that 99% of energy reaching the plattenspieler is via
solid pathways.

>> You can hang the speakers ....
>
> ** Has no effect on TT feedback - you lying asshole.
>
>
>> In commercial applications too numerous to mention I have left a trail of
>> weird fixes (and several tons of bagged Redy-Mix concrete) in my wake.
>
> ** And all along, the only thing that was ever needed was a few coil springs
> under the TT. .

oh do show us..

>
>> Now, being the "cunt head" that I am, off to go fuck myself.
>
>
> ** ROTFL !!
>
> You have been totally FUCKED for the whole of you miserable life - asshole
> .
>
> Cos you were a genetic mental retard from birth.

I was indeed born autistic. It is a lifelong condition that never gets
better. Thanks for the kind words, as always (X)Your old pal Dave.

[Phil Allison]

"dave" <rick...@earthlink.net>

>> ** ROTFL !!
>>
>> You have been totally FUCKED for the whole of you miserable life -
>> asshole.
>>
>> Cos you were a genetic mental retard from birth.
>
> I was indeed born autistic.

** Finally you admit it.

That single, totally condemning fact wipes you out.




... Phil