speaker movement with no sound ?

[SPLOL4]

Hello all

Hope all are well

I am getting a steady rythmic movement of my drivers , with no audible sound , when playing vinyl .

Can anyone tell me what could be causing this ? thank you

 

[Vladimir]

It seems that your table produces rumble. You need to activate the subsonic filter on your preamp.

 

[nopiano]

Sub subsonic output caused by warped records, or mismatch of cartridge compliance with mass of arm. Usually nothing to worry about as long as you don't turn up bass control or play at v high volume, which could overload woofer.

 

[TrevC]

Hello all

Hope all are well

I am getting a steady rythmic movement of my drivers , with no audible sound , when playing vinyl .

Can anyone tell me what could be causing this ? thank you

It's coneflap from the subsonic noise that is present on all vinyl. Amplifiers used to have a rumble filter to remove it, but its rare to see that nowadays. It's harmless unless excessive, in which case using a cartridge with a lower compliance would probably sort it.

 

[SPLOL4]

Thankyou for your replies

I have a project 2 xperience acrylic , evo 9 cc arm and 2m blue cart . unfortunately my pre amp has no sub space filters

I am led to believe that all this should work well together , is there an obvious weak point here ?

 

[Vladimir]

Snap a photo of your setup so we detect visually what might be the problem and not guess in the next 10 pages. :wave:

 

[SPLOL4]

Im sorry i cant upload a pic , it will not let me browse my folders and i dont know how else to do it .

if it helps ?

project 2 xperience/evo9cc/2m blue

rotel rc980bx

rotel rb971 bridged mono

rotel rb971 bridged mono

monitor audio gr 20

the seperates are on an oak rack ( spiked ) and sit between the speakers , the speakers are approx 2 metres apart ( spiked )

 

[SPLOL4]

Think I might have sussed it

 

[SPLOL4]

Maybe not

 

[chebby]

Assuming this all sits on a suspended / cavity wooden floor the solutions may include ...

Siting the TT on it's own wall-mounted shelf or support ...

Moving the equipment rack well away from the speakers ...

Changing the Pro-ject for a suspended subchassis TT

 

[SPLOL4]

My floor is solid Asphalt/concrete , the hifi rack is sat on what was a fire hearth though.

Due to my room layout being designed by the anti audio party moving the rack is out of the question as is buying a new tt , so , a wall mount shelf may be the way .

I assume you are thinking it is an isolation issue ?

 

[andyjm]

Hello all

Hope all are well

I am getting a steady rythmic movement of my drivers , with no audible sound , when playing vinyl .

Can anyone tell me what could be causing this ? thank you

I am afraid that this is one of the "features" of vinyl. To avoid the cutter cutting into adjacent tracks and to reduce high frequency noise, pre-emphasis is applied to the audio signal (the RIAA curve) prior to the LP master being cut. On playback, the reverse of the pre-emphasis (de-emphasis) is applied to the signal to even it all out.

All well and good, but at low frequency this de-emphasis process can apply upward of 20dB of gain to try and bring back the LF from the LP back to the original level. Unfortunately the system can't tell the difference between wanted LF information and warps in the record which also get amplified by 20dB. The net result is wild swings in the bass drivers. This can cause damage, and at the very least reduces the headroom of the amp and can move the voicecoil out of the linear region of the magnets leading to distortion.

In the 'good old days' amps either didn't have frequency response that extended far enough, or there was a deliberate roll off in response to act as a subsonic filter. These days, amps are too good, and don't allow for an imperfect source. If you are wedded to vinyl, you need something with a subsonic filter.

FWIW - this LF gain problem also applies to rumble, one of the reasons rumble is such a problem for vinyl players. Rumble is however audible, and is therefore not subsonic and can't be fixed with a subsonic filter.

 

[Vladimir]

Upload the photo on http://tinypic.com and give us the link (Direct Link for Layouts) that looks something like this: http://i58.tinypic.com/11w33o8.jpg

 

[SPLOL4]

Thank you .

Can subsonic filters be bought alone ? and are there pros and cons involved ?

 

[SPLOL4]

http://tinypic.com/r/2j65zwi/8

 

[andyjm]

Thank you .

Can subsonic filters be bought alone ? and are there pros and cons involved ?

No idea if it is any good, but it describes the problem well.

http://sound.westhost.com/project99.htm

 

[SPLOL4]

Thank you very much I will have a look right now

 

[Vladimir]

Everything on your setup looks excellent. The Rotel RC-980BX has no subsonic filter unfortunatly.

Pro-Ject Phono Box S has a switchable subsonic filter on the back and it's not that expensive (£100). However I don't know if its an upgrade/downgrade from your Rotel phono section.

 

[SPLOL4]

Just been having a look at the phonobox , apparently the phono stage in my Rotel is excellent , but , it has no sub filter , so , looks like Ive got some research to do .

Thank you very much for your time and help , I'll let you know how i get on .

Bye for now

 

[davedotco]

Hi, splol4.

All of the posts above are accurate enough but two things stand out to me. The rack with all that hardware will be pretty heavy, heavy supports are good at passing low frequencys, exactly not what you need.

A wallshelf is a good idea, but some racks, maybe yours, have a separately spiked subtable to fit on top, check it out.

The other issue is ported speakers which load the bass driver in a certain way to improve bass weight and extension. Unfortunately such design means that, an octave below the tuned frequency there is no loading on the bass driver at all, so quite modest sub bass noise can cause excessive movement of the bass cone.

Unlike some people, I think this is an important issue and would look to minimise the problem. Address the turntable support issues first, this should solve the problem but if they do not, a change of pre-amp or speaker might be required.

PS. Check out your floor by moving around the room while playing a record, if your footfall causes obvious movement of the bass cone, then a wall shelf for the player is really important.

 

[davedotco]

Everything on your setup looks excellent. The Rotel RC-980BX has no subsonic filter unfortunatly.

Pro-Ject Phono Box S has a switchable subsonic filter on the back and it's not that expensive (£100). However I don't know if its an upgrade/downgrade from your Rotel phono section.

Nice spot Vlad....

The spec suggests it is 12dB/octave from 20hz, might not be enough. Be nice to see a curve of the response.

 

[Vladimir]

IIRC he said rumble happens while spinning the records even in silent parts. :? I thought rumble is from barings and warped vinyl mostly, not from speakers nearby.

 

[davedotco]

IIRC he said rumble happens while spinning the records even in silent parts. :? I thought rumble is from barings and warped vinyl mostly, not from speakers nearby.

Low frquency noise comes from a variety of sources. Sometimes the output from the speakers causes the equipmen and it's supports to move in sympathy and you get a kind of low level feedback.

Easy enough to check, place stylus on stationary record and stamp your foot, that will tell you whether vibration is getting to the player thriugh the floor.

Then tap the equipment support and finally the chassis of the player itself, easy to see where the noise is getting into the signal.

This might be the time to mention that much of the 'analogue warmth' much loved by vinyl enthusiasts is caused by low level feedback of this type. Strangly bringing up the noise floor in this way seems to make systems sound better, odd but true,

 

[Vladimir]

This might be the time to mention that much of the 'analogue warmth' much loved by vinyl enthusiasts is caused by low level feedback of this type. Strangly bringing up the noise floor in this way seems to make systems sound better, odd but true,

Same for tube amps when microphony happens just enough that its unnoticeable but still makes music bit more reverberant. And people love reverb, makes thing 3D, ambiental, spacious, more real.

 

[pyrrhon]

I do get that too but I realized its caused by vibrations in my case If I walk or play bass louder. I just gave up vinyl for partys and only use for quiet listening when I sit. My house is somewhat shaky :bounce: I was a bit scared the first time I noticed that but It never damaged the woofers.