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Thump noise on the lead in on warped LPs

Hello friends
I have a Mitchell Tecodeck, with a upgraded Garrot Bros P77 cartridge.
I have moved appartments, which means I can turn up the volume a bit, but not that much!!
I have had a bit of a promble, a lot of my mint LP,s were purchased with shwink plastic, and a lot comes with a slight warp(Which I guess is normal)
I have played all above with no prombles, but now seem to have a "Thump" on the lead in track, when the cartridge,arrive to the top, but when the cartridge drops down from a very slight warp, it makes a Thump??, untill, half way thought 1st track, where it settles down
Hopimg some can help
Regards
David
128x128daveyonthecoast
daveyonthecoast's avatar
daveyonthecoast OP
40 posts
 
Dear Friends
Thanks for all the feed back
When I mention that I have moved house, I can have the volume up a bit, thats when I noticed the "thump", om slightey warp LPs, as it has been very hot and humid down here, I have reset VTA etc!!
I was thinking, maybe the cartridge(Garrot Bros new P770 approx 200 hours), before many years ago I was running a Well
Tempered labs clasic,at high volumes, but becaused a long time ago I fogot the MC carridge?
I/m not sure do you all think. may be a promblem with the cartridge(suspension)?
Regards
David
daveyonthecoast's avatar
daveyonthecoast OP
40 posts
 
Dear Friends
Thanks for all the feed back
When I mention that I have moved house, I can have the volume up a bit, thats when I noticed the "thump", om slightey warp LPs, as it has been very hot and humid down here, I have reset VTA etc!!
I was thinking, maybe the cartridge(Garrot Bros new P770 approx 200 hours), before many years ago I was running a Well
Tempered labs clasic,at high volumes, but becaused a long time ago I fogot the MC carridge?
I/m not sure do you all think. may be a promblem with the cartridge(suspension)?
Regards
David
Daveyonthecoast (Threads | Answers | This Thread)
jameswei
883 posts
 
It is possible for a cartridge suspension to fail spontaneously after some period of use.

I don't know much about the Garrot Bros P770, but have you looked to see if the cartridge sinks too close to the vinyl?

I assume you would notice if the cartridge body were actually hitting the record, but a faulty suspension could result in poor tracking ability and cause the thump you are hearing even without the cartridge hitting the vinyl.

Do you have another cartridge to try?
moonglum
619 posts
 
Dear Davey,
Your comment about rising temperatures could be significant.
Each 5 degree C temperature change could be equivalent to 1mm of VTA. This is how much you should be looking to compensate for once it swings away from the ideal 21-22C.

If I'm not in error, each 4mm of VTA is equivalent to a 1 degree change of angle(9" arm).
4mm VTA change needs approx 0.25g VTF compensation.

If the cart is indeed "bottoming", it doesn't surprise me that it normalises halfway through the first track. If you were having serious suspension problems I'd expect you to get less specific instances of record contact.

Hope this helps.
Kind regards....
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