Thump noise on the lead in on warped LPs

Hello Davey...
I agree the likeliest explanation is the cart could be "bottoming" on the warp.
Also agree tapered SMEs and warps do not mix well.

If you are using a technodec then chances are you are using a Technoarm(?) I'm not sure these come with ready VTA adjustment. (Perhaps owners will advise?)

If this be the case you have options :

1. Shim the arm at the base.
2. An easier, less stressful fix is if the Technodec uses a 5mm mat you could try a thinner one e.g. Ringmat with Latex underlay (4mm), bare Ringmat (3mm) or the 3mm Achromat?

Kind regards...

PS : You may have to increase the VTF after any of these moves.

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

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)

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?

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....