helma
22-12-2017, 17:35
So I finally got around to testing the fluid damping feature of my Sumiko MMT. While I'm under the impression the Jelco 750D is a superior arm, outwardly they look pretty much identical and the damping system is exactly the same. I have two Lencos, other one has a Fidelity Research FR-54 for a tonearm, the other one has the Sumiko. In my past test (using the same cartridge on both) I preferred the FR-54 by slight margin. The Sumiko is a good arm but the FR-54 to my ears was a little step ahead, just generally a bit cleaner sounding.
Currently I have a AT15Sa mounted on the Sumiko and an Ortofon MC10 Supreme on the FR-54. Running these two cartridges head to head on the same arm, the AT15Sa always came up short to my ears. While it was always very clean sounding, it seemed a bit overly polite and not quite as transparent in the midrange especially. Yesterday I got a bottle of 10,000 cSt silicone oil (more on the viscosity later), did a "before" needledrop of a lead in groove + the first track, added few drops of the silicone oil into the damping well and redid the needledrop. I just wanted to get some objective info on what it does and that it's working. Doing a spectrum analysis of same portion of the lead in groove and it was clearly visible the cartridge resonance peak at 9Hz was diminished by a few dB. Also the 0-20Hz range was a bit clearer all around. What was surprising is that the peak after adding the silicone oil was actually more pronounced because everything around it was so much cleaner, but I was under the understanding damping should actually lessen the Q, spreading the resonance around with a less pronounced peak. So while the peak was about -3dB lower, it sort of stuck out more, because the surrounding frequencies were cleaned up to -6dB.
Anyway looking at the changes on spectrum analyzer, they didn't seem that big a deal (while cleaner, this stuff was already -50dB or so below actual music levels, except for the resonance peak wich was in the -30-40dB range) so I wasn't expecting much from actual listening. But the AT15Sa sounds sublime on that arm now. It's still not as "lively" as some other cartridges, but it sounds more dynamic now, because of the clarity of the music and the "emptiness" in soundstage is more empty now, making instruments stuck out more and the good qualities it always had are also emphasized, there's even better clarity and detail and the soundstaging seems more 3-dimensional now. It's hard to describe the changes, in a way they are subtle but also not, it's like a layer of extranous noise was removed from the sound(s) and only the music remained.
And now back to the viscosity, the RC car shop was low on stock on silicone oils and 10k was the closest I could get to 30k which is what I was planning on buying. The KABUSA damping kit for SL-1200 arm uses 60,000 cSt oil and on their website it says that is the thickest stuff that's still classified as "fluid" and also that less viscous stuff doesn't damp as effectively. I tried researching what Jelco ships with the arm, but couldn't find solid information, there was one Jelco email that stated 500cPs (which I understand should be very close to 500cSt) which is a lot more closer to water than even what I currently have and seems it can't simply be true, I don't think that would provide much damping at all. Other information I found suggested anything from 10k to 60k and even stating that the Jelco arms use same stuff for damping as for the cue levers, which also can't be right since the cue lever oils are usually in the range of 200k-500k or so - that stuff is more like a very thick grease.
I have 500k oil I got before for a cue lifter and I think I coud mix a tiny drop of that with the 10k stuff to get any viscosity between the two, so I might try that at some point, but I was wondering if anyone has experimented with different fluids and what worked best. Also how runny is the stuff that ships with the Jelco arms? The 10k is still clearly fluid, but it's approaching runny honey though I'd say it's more 'watery' than that.
Clearly the 10k works, it might not be optimal but at least subjectively the arm sounds way better now and I'm confident it's not overdamping but rather erring on the other side, which is good. I think with damping erring the side of too little is better than too much and certainly the sound didn't get killed with the 10k silicone oil, even though I used quite a lot of it (I kept adding it to see if there was better damping, but actually it seemed I already got past the optimal point so I might try to take some away - though I thought adding it would just be more and more damping, it seems from the spectrum analysis that my initial amount actually damped better??)
Fluid damping in arms is all new to me, but certainly seems a worthy thing to do, I might even try to put together a DIY damping trough for the FR-54 and see if I can make it work and if it would be an improvement. I could put the trough on top of the plinth under the counterweight and use somekind of paddle extending from the counterweight stub into the fluid. Not sure how effective that would be but I guess worth a try.
Currently I have a AT15Sa mounted on the Sumiko and an Ortofon MC10 Supreme on the FR-54. Running these two cartridges head to head on the same arm, the AT15Sa always came up short to my ears. While it was always very clean sounding, it seemed a bit overly polite and not quite as transparent in the midrange especially. Yesterday I got a bottle of 10,000 cSt silicone oil (more on the viscosity later), did a "before" needledrop of a lead in groove + the first track, added few drops of the silicone oil into the damping well and redid the needledrop. I just wanted to get some objective info on what it does and that it's working. Doing a spectrum analysis of same portion of the lead in groove and it was clearly visible the cartridge resonance peak at 9Hz was diminished by a few dB. Also the 0-20Hz range was a bit clearer all around. What was surprising is that the peak after adding the silicone oil was actually more pronounced because everything around it was so much cleaner, but I was under the understanding damping should actually lessen the Q, spreading the resonance around with a less pronounced peak. So while the peak was about -3dB lower, it sort of stuck out more, because the surrounding frequencies were cleaned up to -6dB.
Anyway looking at the changes on spectrum analyzer, they didn't seem that big a deal (while cleaner, this stuff was already -50dB or so below actual music levels, except for the resonance peak wich was in the -30-40dB range) so I wasn't expecting much from actual listening. But the AT15Sa sounds sublime on that arm now. It's still not as "lively" as some other cartridges, but it sounds more dynamic now, because of the clarity of the music and the "emptiness" in soundstage is more empty now, making instruments stuck out more and the good qualities it always had are also emphasized, there's even better clarity and detail and the soundstaging seems more 3-dimensional now. It's hard to describe the changes, in a way they are subtle but also not, it's like a layer of extranous noise was removed from the sound(s) and only the music remained.
And now back to the viscosity, the RC car shop was low on stock on silicone oils and 10k was the closest I could get to 30k which is what I was planning on buying. The KABUSA damping kit for SL-1200 arm uses 60,000 cSt oil and on their website it says that is the thickest stuff that's still classified as "fluid" and also that less viscous stuff doesn't damp as effectively. I tried researching what Jelco ships with the arm, but couldn't find solid information, there was one Jelco email that stated 500cPs (which I understand should be very close to 500cSt) which is a lot more closer to water than even what I currently have and seems it can't simply be true, I don't think that would provide much damping at all. Other information I found suggested anything from 10k to 60k and even stating that the Jelco arms use same stuff for damping as for the cue levers, which also can't be right since the cue lever oils are usually in the range of 200k-500k or so - that stuff is more like a very thick grease.
I have 500k oil I got before for a cue lifter and I think I coud mix a tiny drop of that with the 10k stuff to get any viscosity between the two, so I might try that at some point, but I was wondering if anyone has experimented with different fluids and what worked best. Also how runny is the stuff that ships with the Jelco arms? The 10k is still clearly fluid, but it's approaching runny honey though I'd say it's more 'watery' than that.
Clearly the 10k works, it might not be optimal but at least subjectively the arm sounds way better now and I'm confident it's not overdamping but rather erring on the other side, which is good. I think with damping erring the side of too little is better than too much and certainly the sound didn't get killed with the 10k silicone oil, even though I used quite a lot of it (I kept adding it to see if there was better damping, but actually it seemed I already got past the optimal point so I might try to take some away - though I thought adding it would just be more and more damping, it seems from the spectrum analysis that my initial amount actually damped better??)
Fluid damping in arms is all new to me, but certainly seems a worthy thing to do, I might even try to put together a DIY damping trough for the FR-54 and see if I can make it work and if it would be an improvement. I could put the trough on top of the plinth under the counterweight and use somekind of paddle extending from the counterweight stub into the fluid. Not sure how effective that would be but I guess worth a try.