issue on tests

Post: # 13357Unread post **dietrich10** Mon Mar 14, 2011 6:06 pm

Have not had this issue before.
There is almost a rumbling heatbeat on the entire A side of a cut I did for a client recently.

thoughts?

Post: # 13360Unread post **JayDC** Mon Mar 14, 2011 6:29 pm

well on my lathe that would be from the idler drive, since they can easily do that, especailly if there is dirt or something on the platter rim..

I would check your drive train, it has to be something that is connected to the platter, since your overhead never touches that actual turntable.

Maybe its time to clean out and re-lube your gear boxes.. if it's belt drive, I bet there is a lump on the belt.

Post: # 13361Unread post **opcode66** Mon Mar 14, 2011 6:43 pm

Hey D, are you setup back in your normal cutting room? Could that have possibly been noise/vibrations carried through the floor? Not sure if you have old girl setup on a proper base or not.

I've heard of having a dry carriage track causing vibration in the carriage that can translate to disc. Maybe you just needed to oil the track?

Are other cuts you've made since then showing the same issue?

Dirty power to the amps or ground loop can definitely cause a low frequency rumble in the audio chain.

Hope you sort this out. Curious to know what the cause was.

Post: # 13362Unread post **dietrich10** Mon Mar 14, 2011 6:46 pm

I cut at least 7 other records within 48 hours of the record in question and it was 4 weeks ago. No other records with issue...very odd

The Neumann overall running smooth and quiet

Post: # 13363Unread post **JayDC** Mon Mar 14, 2011 6:55 pm

I woulds still check your drive train, there is probably foreign material that is making the heartbeat, about once per rotation.

Post: # 13364Unread post **opcode66** Mon Mar 14, 2011 7:20 pm

He has a 70 like me. The drive motor connects directly to the plater via a shaft. The plater rides on bearings packed in oil and sealed up tight. If there was a problem it would show up on every cut. You would be able to notice the platter rumbling. It would have to be quite significant given the weight of the platter, ring and vaccuum table.

Post: # 13365Unread post **JayDC** Mon Mar 14, 2011 7:33 pm

opcode66 wrote:He has a 70 like me. The drive motor connects directly to the plater via a shaft. The plater rides on bearings packed in oil and sealed up tight. If there was a problem it would show up on every cut. You would be able to notice the platter rumbling. It would have to be quite significant given the weight of the platter, ring and vaccuum table.

Oh wow, so its a low RPM motor.. neeto.. The only thing to check is what you mentioned above, the bearings.. I'm not sure what else would create a heartbeat since that is happening at regular intervals.. Unless there was dirt or something under the plate (chip?), and it was slightly wobbling up and down throughout the cut.

I don't see the overhead arm doing it, since it never comes into contact with the platter, and I highly doubt that it's a sound coming from the needle..

I would think this type of thing never happens on a VMS, I could see it easily on the presto though..

Post: # 13366Unread post **dietrich10** Mon Mar 14, 2011 7:36 pm

I would think this would of been on other cuts that day and even to this day.

Post: # 13367Unread post **JayDC** Mon Mar 14, 2011 7:38 pm

is it possible that it's something that came about during the metal process?

is it still doing it, if you cut a dub?

Post: # 13368Unread post **opcode66** Mon Mar 14, 2011 8:04 pm

A dry carriage track can cause noise. It is a fact. Here's why. The cutterhead is connected to the suspension box. The suspension box is connected to the carriage. The carriage rides a track connected via a dovetail configuration. If the track is dry the carriage will vibrate as it travels the diameter of the disc. Since the carriage connects to the head indirectly, if the carriage is vibrating, the head is vibrating. Vibrations will transfer happily to the groove being cut.

Sounds to me like you got a bad master lacquer. I've seen some that when held to the light correctly I can see striations in the cellulose. Sort of lines that run the diameter of the disc from center hole to edge. Possibly is was just a bad disc and that is why there is a regular audible background noise.

Post: # 13369Unread post **jjgolden** Mon Mar 14, 2011 8:07 pm

Hi Dietrich,

Could be "Orange Peel"
Do you have the test pressing in question?
If so, does that A side have an unclear rippled look to it?
..... as opposed to a smooth glassy look.
Like the surface of an Orange?
This would be most visible in the land of the lead out grooves.
It can be heard as you described.. a consistent rumble.

JJG

Post: # 13371Unread post **JayDC** Mon Mar 14, 2011 8:17 pm

I would think that sound contamination from the carriage would be more of a constant sound, and not a revolving sound, could be wrong.. usually am..

Post: # 13375Unread post **dietrich10** Mon Mar 14, 2011 9:20 pm

I have tests but did not look under the scope yet(in the morning).
could be some dirt/dust etc under the carriage during this cut...I could a high profile client LP the cut right before this which was approved and plated same place...

Post: # 13376Unread post **jjgolden** Mon Mar 14, 2011 9:26 pm

Cool.
This Orange peel would be visible naken eye.

Post: # 13391Unread post **dietrich10** Tue Mar 15, 2011 10:29 am

Plant claims its their end. mystery solved