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.
wilson667
Did you change the settings on your phono stage to what the specs call for on the new cart?
Effective mass of the JWM 9 is 7.7g. The AT150MLX weighs 8.3g and the mounting hardware add 0.5g for a total effective mass of 16.5g. AT150MLX dynamic compliance is 10. If you run those figures through the resonance frequency calculator, you get a resonance frequency of 12.29 Hz, which is at the upper end of the 8-12 Hz recommended frequency range. If you can see the woofers pumping, that may be a damping issue of some sort, the kind moderated by a fluid-damped tonearm.

You can also lower the resonance frequency into the 10's by adding headshell weights to bring effective mass up to around 20-25 Hz.
It's not a good tonearm to begin with.
None of the vpi arms are really.
What doesn't look right to me is flexistand? Don't know what that is, but VPI's don't like flex. You're right with the other stuff...a solid connection to Earth. I would take it off the flex stand and see what happens.. Also damping may cure this. Add just 1 drop at a time and listen. If the sound becomes soggy...take out one drop with a Qtip and try again.
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
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!
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.
"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.

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.
Hey Johnnyb53
thanks for pointing that out I totally grazed over adding the weight of the cartridge to the calculation.Is there any way to see if the added weight will work perhaps a penny and some blue tack? Another thing has got me confused Audio-Technica does their compliance calculations at 100hz and not 10hz as the calculator calls for. I have no idea how to do the conversion to the 10hz number that is required.
Andrew9405
It is not very helpful in solving my problem to tell me the arm is not very good. It is what I have to work with. I don't want this to devolve in to a debate about how good the arm is or is not.
Zd542
I did say [http://www.tnt-audio.com/clinica/flexye.html]flexy[/url] It is not quite the flexy stand outlined by tnt audio with only three legs it is more like a salamander nock off it has 4 legs and i used salamander's points for the feet.it is a very solid stand.
I knew somebody used a different frequency for its compliance calculation,
but forgot that it's AT. For that you might ask a customer service rep at
LpGear how the 100Hz spec translates at 10 Hz. It could be that your
compliance is spot on and something else is amiss.

When you think about it, a high amplitude cart/arm resonance in the 12 Hz
range would cause the woofer to flutter rather than pump, as the woofer
excursions would be 1/12th of a second apart. Visible woofer pumping
would occur at a few Hz (e.g., 5) or less, more like 1 or 2 Hz.

So maybe this is related to 33-1/3 rpm, which, if eccentric, would be about
1.8 Hz, ideal for visible pumping.

So what could cause eccentric tracking? I could guess a few:

o Antiskate out of adjustment
o Record with off-center hole
o Cartridge azimuth out of alignment
o Tracking weight too high
o Belt stretched and needs replacing
o Platter bearing needs lubrication
o Turntable not absolutely level
o Maybe even VTA or SRA setting

Something along those lines.
"I did say [www.tnt-audio]flexy[/url] It is not quite the flexy stand outlined by tnt audio with only three legs it is more like a salamander nock off it has 4 legs and i used salamander's points for the feet.it is a very solid stand.
Wilson667 (System | Threads | Answers | This Thread)"

I see it now. The top shelf looks like plexiglass, so that's where I got the idea from. I have 2 Scouts and one of them is on a stand similar to this. Its one of the ones that Michael Green designed and sold through The Cable Co. I've never had any problem like this with either one. The only real difference I can see is that I use lower output MC carts, but I don't see why that would make a difference. Of all the answers so far, Johnnb53's seem to be the most plausible.