The Captain
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Hi Avon, great thinking.. alas with an old naim 32-5, no possibility. If only tho, & I could narrow down this thing.
Arm & Cart xyz
- Thread starter The Captain
- Start date
Hi Avon, great thinking.. alas with an old naim 32-5, no possibility. If only tho, & I could narrow down this thing.
The Captain
~~~~~~~~~~
@cobbers Ah yes I recall your armbaord swap, didn't read before that you had -exactly- my symptoms though.
Thing is, Lp12 bits being so costly, to scratch this itch.. what £75 extra for such an armboard? & thst's still without definitively knowing it will work, in my set up. Too expensive just as a 'try' I think really.
I could only consider modifying my old mdf one. Your pT1 ones are diddy compared to Lp12's, sat at the back without a logo on- I'd imagine you could diy one cheaply enough. Not so for me really.
One thing in the 540's favour (as said I do think good things about it, even if I think it has a flawed low half) is it just got me playing Lp's, alot. Piles of them sat about after 2 weeks. Kinda addictive. But only the ones that sounded good, with this cart. Not my usuals. An odd sutuation. Messed with my head a bit: for eg, Grace Jones, Metallica, all the police ones almost in repeat, even dire.. ahem.. straits?? This is decidedly --not-- my usual playlist, but simply sounded outstanding with the 540 (partly to do with the bass bloom was either in control with these, or at a minmum, purely due to excellent studio recording/ production reasons).
Thanks, Capt
Thing is, Lp12 bits being so costly, to scratch this itch.. what £75 extra for such an armboard? & thst's still without definitively knowing it will work, in my set up. Too expensive just as a 'try' I think really.
I could only consider modifying my old mdf one. Your pT1 ones are diddy compared to Lp12's, sat at the back without a logo on- I'd imagine you could diy one cheaply enough. Not so for me really.
One thing in the 540's favour (as said I do think good things about it, even if I think it has a flawed low half) is it just got me playing Lp's, alot. Piles of them sat about after 2 weeks. Kinda addictive. But only the ones that sounded good, with this cart. Not my usuals. An odd sutuation. Messed with my head a bit: for eg, Grace Jones, Metallica, all the police ones almost in repeat, even dire.. ahem.. straits?? This is decidedly --not-- my usual playlist, but simply sounded outstanding with the 540 (partly to do with the bass bloom was either in control with these, or at a minmum, purely due to excellent studio recording/ production reasons).
Thanks, Capt
The Captain
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Now I understand why some uber-nerds, have 2 tonearms. Well, rather I can see how -I- could use two.
I'd have the 540 on one 774, and my shelter 201 on another. (75-85) Rush Lp's etc.. many of which excellent recordings & very much on my usual playlist, on the shelter. Police, MJ thriller, etc.. on the 540.
What I want therefore ideally- is the top half of the 540, & the bottom half of the Shelter in one cart. Wishful thinking.
I'd have the 540 on one 774, and my shelter 201 on another. (75-85) Rush Lp's etc.. many of which excellent recordings & very much on my usual playlist, on the shelter. Police, MJ thriller, etc.. on the 540.
What I want therefore ideally- is the top half of the 540, & the bottom half of the Shelter in one cart. Wishful thinking.
The Captain
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Ah I thought you had those symptoms with the 740, & alieviated it with the new board.
Hmm. So that's £45 for really a totally blind try (& a board with which I'd I lose my lovely "Lp12 Linn Sondek" & the logo too). It's just too much. I can only do this via a used, ply of somekind, dedicated lp12 / sme cutout armboard. Rare as hen's teeth I'd think, but will keep an eye out.
If I see a used 740ML tho, could try this to see if the bass bloom is cured by the metal body, as I could sell on having only put ~10hrs extra on it. I just don't have money you see to spend on only 'possible' fix attempts.
Thanks, Capt
Avon
pfm Member
I believe this is significant and it relates back to that Vinyl Engine article. And a different cartridge had a similar bass problem too.
In theory, the only difference between the AT-VM540ML and the AT-VM740ML is that the latter is 1.6 grams heavier. You could just stick some Blu Tack onto the headshell to simulate that (and obviously rebalance the arm). It would reduce the resonance frequency of the whole by a few Hz. The problems you’re having are much higher up though I think.
a.palfreyman
pfm Member
Anyone got any aluminium cart screws to fit the threads in the 774, preferably cheese-head so I can grip the head? (Ooer...)
I have some that are 5.5mm long but suspect that these are too short to be able to do anything with. If so, send me 3 (Midland UK) and I'll try to modify them into a captive screw and post onto @The Captain. We really need to know if the cart not contacting the arm properly is the problem here.
I have some that are 5.5mm long but suspect that these are too short to be able to do anything with. If so, send me 3 (Midland UK) and I'll try to modify them into a captive screw and post onto @The Captain. We really need to know if the cart not contacting the arm properly is the problem here.
cobbers
pfm Member
Personally I do not believe this quality problem is anything to do with the AT itself per-se - there is something to do with the interaction of the 774 and the MDF that is being magnified by that particular combination of 774 and AT.
Perhaps even some isolation between the arm baseplate and armboard (4 washers perhaps)?
I have grown to dislike MDF as an armboard material over many years hence my experimentation with fitting a Roksan Nima (with it's tiny point bearing contact) to an LPT (the best sounding tonearm I ever used on an LPT).
Perhaps listening on headphones for a time might help to isolate the 'problem' as it could be exaggerated by the LP12's interaction with the room acoustics.
I have not noticed any difference on any of my cartridges from a £50 old stock (1970's vintage) Empire quadraphonic to a Denon DL-304 which I sold end of stylus life for £200+ on my non-MDF armboards on the PT1.
Perhaps even some isolation between the arm baseplate and armboard (4 washers perhaps)?
I have grown to dislike MDF as an armboard material over many years hence my experimentation with fitting a Roksan Nima (with it's tiny point bearing contact) to an LPT (the best sounding tonearm I ever used on an LPT).
Perhaps listening on headphones for a time might help to isolate the 'problem' as it could be exaggerated by the LP12's interaction with the room acoustics.
I have not noticed any difference on any of my cartridges from a £50 old stock (1970's vintage) Empire quadraphonic to a Denon DL-304 which I sold end of stylus life for £200+ on my non-MDF armboards on the PT1.
a.palfreyman
pfm Member
Don't know if this has been asked but do you have the same 'offending' albums on CD? If so, does the CD version suffer the same bass-boom issues? If not, then it could be acoustical/mechanical feedback into the tt.
IIRC the LP12 has an upper bass 'bloom' depending upon the sub-chassis/arm board combination, which is what I think @cobbers is getting at. It may also be worth placing your head right over the tt when you play the offending track on CD to see if the troublesome notes seem louder with your head over the tt than say your normal listening position. If this occurs, your tt is sitting in a room node (where the offending note is artificially amplified by the room). If you don't have a room node at the tt, then it could be mechanical feedback through the floor/tt support.
IIRC the LP12 has an upper bass 'bloom' depending upon the sub-chassis/arm board combination, which is what I think @cobbers is getting at. It may also be worth placing your head right over the tt when you play the offending track on CD to see if the troublesome notes seem louder with your head over the tt than say your normal listening position. If this occurs, your tt is sitting in a room node (where the offending note is artificially amplified by the room). If you don't have a room node at the tt, then it could be mechanical feedback through the floor/tt support.
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cobbers
pfm Member
Hence my thought regarding the use of headphones.
a.palfreyman
pfm Member
Yerbut it seems he doesn't do headphones unfortunately...
Was reading on vinyleengine a suggestion to place a record on the tt and place the arm onto the stationary record, having the output of the phono stage going to a tape recorder. Then play a CD through the speakers. If the tt is suffering feedback, you will hear it on the tape when you play it back.
Was reading on vinyleengine a suggestion to place a record on the tt and place the arm onto the stationary record, having the output of the phono stage going to a tape recorder. Then play a CD through the speakers. If the tt is suffering feedback, you will hear it on the tape when you play it back.
The Captain
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Hi chaps @cobbers thanks so much for your kind offer. Alas I don't have the 540 now, so couldn't pop the stylus on. Ideal idea though. I'm using a k9 with the 95SH stylus on. And swapping this with the k9 stylus. Both have the same bass bloom.
I'm actually considering a 740ml. With it's flaws (assuming similar to a 540) warts & all.. the way it played -some- Lp's was so good, I'm now kinda yearning for the one I sold back. But think a sensible idea would be fork out the extra £20 for the metal bodied version.
The cart is firmly tethered to the headblock, I tighten up without overtightening, I know what force to use.. been doing this off & on with carts for 40 yrs, & I'm a bbc ex camera technician so I'm not ham fisted.
@Avon I did try the +1.5 gms weight addition to the headblock, suggested by Craig or Cobster early doors. No difference. And also early doors: I ruled out the cd player (as I did all with other carts prior these recent string of AT's too), before I decided to ask on a thread, having determind -zilch- bass bloom with my cdp. Not so much as a hint of this wonkyness, with anything other than these 3x AT's. And the k9 (which I'll call AT no.4).
Logic I can follow you see, & rule out everything so not to be a twerp, before finally asking asking on here as a last resort. I still have to conclude, that it's these AT's at fault, I think you can understand this follows simple logic to say this.. but I'm still very happy to be proven wrong.. although I just don't see how this is possible myself.
Thanks most kind of y'all to help. Capt
I'm actually considering a 740ml. With it's flaws (assuming similar to a 540) warts & all.. the way it played -some- Lp's was so good, I'm now kinda yearning for the one I sold back. But think a sensible idea would be fork out the extra £20 for the metal bodied version.
The cart is firmly tethered to the headblock, I tighten up without overtightening, I know what force to use.. been doing this off & on with carts for 40 yrs, & I'm a bbc ex camera technician so I'm not ham fisted.
@Avon I did try the +1.5 gms weight addition to the headblock, suggested by Craig or Cobster early doors. No difference. And also early doors: I ruled out the cd player (as I did all with other carts prior these recent string of AT's too), before I decided to ask on a thread, having determind -zilch- bass bloom with my cdp. Not so much as a hint of this wonkyness, with anything other than these 3x AT's. And the k9 (which I'll call AT no.4).
Logic I can follow you see, & rule out everything so not to be a twerp, before finally asking asking on here as a last resort. I still have to conclude, that it's these AT's at fault, I think you can understand this follows simple logic to say this.. but I'm still very happy to be proven wrong.. although I just don't see how this is possible myself.
Thanks most kind of y'all to help. Capt
cobbers
pfm Member
No prob's - but you may need extra mass on the counterweight for the 740.
Would be interested to know what the effect would be by substantially isolating the baseplate from the MDF perhaps with some small diameter rod.
https://www.ebay.co.uk/itm/33419046...d=link&campid=5338728743&toolid=20001&mkevt=1
Would be interested to know what the effect would be by substantially isolating the baseplate from the MDF perhaps with some small diameter rod.
https://www.ebay.co.uk/itm/33419046...d=link&campid=5338728743&toolid=20001&mkevt=1
This site contains affiliate links for which pink fish media may be compensated.
Avon
pfm Member
It’s pointless getting another AT cartridge until the problem with the armboard is resolved. Cobbers had the same problem and resolved it.
I know nothing of the LP12 either, but can you not dampen the board with say Blu Tack? That comes in sheets which could be pressed on. If it’s likely to cause discolouration, could it not be pressed on from the bottom? It’s weight will displace the suspension perhaps, but at least it would point you in the right direction.
I know nothing of the LP12 either, but can you not dampen the board with say Blu Tack? That comes in sheets which could be pressed on. If it’s likely to cause discolouration, could it not be pressed on from the bottom? It’s weight will displace the suspension perhaps, but at least it would point you in the right direction.
a.palfreyman
pfm Member
If you look at the sub chassis/arm board assembly you have this:
Any flexure of the arm board will probably incorporate some twist too as the edge of the underlying sub chassis is angled.
Bending stiffness = elastic modulus times moment of inertia.
Elastic modulus of MDF is in the region of 2.6 to 4.2 GPa. Assume 3.3GPa
Moment of inertia I is breadth times thickness cubed divided by 12. Assuming breadth b=0.08m and thickness t=0.012m then I=11x10^-9 and bending stiffness k is thus about 37.
Now natural resonant frequency Fr = root (k/m) where m is mass.
Assume about 50g for the portion of arm board that overhangs and about 250g for the arm itself (so total of 0.3kg) and Fr = root (37 / 0.3) =11Hz.
According to the resonance calculator on vinylengine and assuming that the cartridge compliance at 10Hz is about 1.7 times the dynamic compliance (at 100Hz,) then the cartridge compliance of the AT carts on an effective mass arm of 5.5g gives about 11Hz, so the arm/cart and arm/arm board resonance could well be the same.
There are a lot of assumptions here, but this would tie in with what is happening. Clearly it isn't a resonance of 11 hz that is the problem but I reckon that say a fifth or seventh harmonic (mid-50 or 80ish Hz) might excite both the arm/cart and the arm/arm board simultaneously and it will also respond to acoustic feedback into the arm board.
What do you think? Any disagreements with the above?
Any flexure of the arm board will probably incorporate some twist too as the edge of the underlying sub chassis is angled.
Bending stiffness = elastic modulus times moment of inertia.
Elastic modulus of MDF is in the region of 2.6 to 4.2 GPa. Assume 3.3GPa
Moment of inertia I is breadth times thickness cubed divided by 12. Assuming breadth b=0.08m and thickness t=0.012m then I=11x10^-9 and bending stiffness k is thus about 37.
Now natural resonant frequency Fr = root (k/m) where m is mass.
Assume about 50g for the portion of arm board that overhangs and about 250g for the arm itself (so total of 0.3kg) and Fr = root (37 / 0.3) =11Hz.
According to the resonance calculator on vinylengine and assuming that the cartridge compliance at 10Hz is about 1.7 times the dynamic compliance (at 100Hz,) then the cartridge compliance of the AT carts on an effective mass arm of 5.5g gives about 11Hz, so the arm/cart and arm/arm board resonance could well be the same.
There are a lot of assumptions here, but this would tie in with what is happening. Clearly it isn't a resonance of 11 hz that is the problem but I reckon that say a fifth or seventh harmonic (mid-50 or 80ish Hz) might excite both the arm/cart and the arm/arm board simultaneously and it will also respond to acoustic feedback into the arm board.
What do you think? Any disagreements with the above?
cobbers
pfm Member
My problem may have been with the Empire - too long ago now to be sure - just a 'lack of notes' no definition to the bass end which is certainly not what the PT1 can be accused of (it was originally bought with a simple folded ally board).