2. analog
  3. 1442622940

Is the at 150mlx a bad match on the jmw9 tonearm

I am asking because I just installed the at150mlx on my vpi scout 1.1 and am getting woofer pumping. I had a ortofon 2m blue before this and had no pumping. The table is on a flexy style stand with 4 butcher block shelves and a laminated top shelf of 1/2" acrylic ,1/2" aluminum, 1/2" acrylic. The table sits on the top shelf on top of a sand box. The stand is spiked into carpet on a concrete slab. It is located about 12' away from the right speaker behind the listening position. I am not sure what other information would be helpful but it seems to happen at normal listening levels( slightly louder than conversation).If it is a bad match I would like to figure it out ASAP and return it for something else. Thank you for any help.
128x128wilson667
wilson667's avatar
wilson667 OP
93 posts
 
Zd542 My phono pretty is am Avid Pulsus and is set to 47000 k ohoms and a capacitance of 100pf.
Johnnyb53 I am not sure that I want to add a headshell weight. It sounds like you are saying adding a weight of about 13 to 18 grams.that seem like an awful lot of weight to add.
Stringreen unfortunately I don't believe the damping is an option on this arm.I am not sure the stand is the problem but I am going to try moving the table and see what happens.I think there are some pics of the stand in my system page although most everything else has changed. The stand its self is near 150 pounds and not as flexy as the name would give the impression.
I am kind of starting to think it is just not a good match to the arm. I thought I saw a few threads of folks with it on the same arm but I could be wrong
yogiboy's avatar
yogiboy
5,529 posts
 
A low mass arm and a low compliance cartridge is not a good match. That is the reason why you did not have woofer pumping with the higher compliant Ortofon. Return the cartridge for one with a higher compliance or you will have woofer pumping until the cows come home!
stringreen's avatar
stringreen
6,388 posts
 
Wilson...it looks like they have changed the arm since you got your table...the new ones can be damped...they come with a bottle of damping fluid. Also...I know this is an anathema, but try no anti-skate. Makes the cartridge sound better to my ears.
zd542
5,339 posts
 
"09-19-15: Stringreen
What doesn't look right to me is flexistand? Don't know what that is, but VPI's don't like flex."

Look at the pic of his rack. I think he meant plexy not flexy.
johnnyb53
3,510 posts
 

09-19-15: Wilson667
Johnnyb53 I am not sure that I want to add a headshell weight. It sounds like you are saying adding a weight of about 13 to 18 grams.that seem like an awful lot of weight to add.
No. The effective mass of the tonearm alone is 7.7g. The mass of the cartridge plus hardware adds 8.8g for a total effective mass of 16.5g. This is an unmodified effective mass, as VPI would certainly know that the cartridge is going to weigh something in that range.

So I'm talking about adding a headshell weight of 3 to 5g. VPI even makes a 3g headshell weight for JMW tonearms, so it must be OK with them too.
More to discover