I've been struggling to confirm the affective mass of the tonearm on this KP-1100 I ordered from Japan last year. I get a different answer from various LLMs depending on the day. Using those same LLMs but asking it to search specific foreign languages I found this German language forum where a two guys named Mario and Jürgen Heiliger took a KD-990 apart and weighed everything in 2009.
KD-990 takedown
I thought it might be worth referencing in the English language world so I am posting this. Interestingly, Mario weighed the bare tonearm tube at 9.80g and the headshell at 11.24g, simply adding them together (plus screws) to claim an effective mass of roughly 20.50g. Jürgen supported this, stating that old magazines and his own calculations using a test record and a Denon DL-103 cartridge pointed to 22g. Mario’s static weight measurements were probably correct, but his physics were flawed. Effective mass is a measure of rotational inertia, not static weight. By taking Mario's raw weights and applying the moment of inertia formula (M_e = \frac{I}{L^2}), we (ie. a LLM) confirmed that the actual effective mass is ~17.5g with the stock head shell and bare tonearm effective mass of 6.26g
These numbers and other mistakes have been echoed around the internet by other forum posting and now via LLM's not digging deep. With this spec not ever published by Kenwood it seems to have taken a life of it's own.
Unfortunately further confusion lies as the tonearms on the KP-1100 (and other "x-frame) Kenwoods are split into the Dynamic Stability for the high tier and High Stability for the mid-tier. Unfortunately I can't find clarification on the otherwise visually identical tonearms. It appears the only difference was the bearing setup, knife edge for the DS and normal ball bearing for the HS. Not sure I buy that as I can't find actual pictures showing the difference but I'm not taking apart my tone arm so there ya go.
https://www.picclickimg.com/00/s/MT...wood-KP-KD-7010-990-9010-1100-Tonearm-_57.jpg
https://www.stereonet.com/forums/to...p-9010-direct-drive-semi-automatic-turntable/
My personal experience for what little it is worth is that my AT540ML and my generic 10gr headshell does okay on my concrete floors and floppy records but if you listen on a particularly warped record you can make out some wavering or as I like to think of it, extra vibrato. If the above is accurate it should be almost exactly a 8hz match. Not sure if it could be improved upon but I ordered a used Denon PCL-5 tonearm that weighs 6gr to see if it helps. I'll include some other options using the Denon(6g)or the nice AT-LH11H (11g) headshell I like because its got adjustable azimuth so no shimming. The AT-OC9XML is a bummer. Appears to be a forum favorite but it seems to be setup for modern turntables with lighter tonearms.
KD-990 takedown
I thought it might be worth referencing in the English language world so I am posting this. Interestingly, Mario weighed the bare tonearm tube at 9.80g and the headshell at 11.24g, simply adding them together (plus screws) to claim an effective mass of roughly 20.50g. Jürgen supported this, stating that old magazines and his own calculations using a test record and a Denon DL-103 cartridge pointed to 22g. Mario’s static weight measurements were probably correct, but his physics were flawed. Effective mass is a measure of rotational inertia, not static weight. By taking Mario's raw weights and applying the moment of inertia formula (M_e = \frac{I}{L^2}), we (ie. a LLM) confirmed that the actual effective mass is ~17.5g with the stock head shell and bare tonearm effective mass of 6.26g
These numbers and other mistakes have been echoed around the internet by other forum posting and now via LLM's not digging deep. With this spec not ever published by Kenwood it seems to have taken a life of it's own.
Unfortunately further confusion lies as the tonearms on the KP-1100 (and other "x-frame) Kenwoods are split into the Dynamic Stability for the high tier and High Stability for the mid-tier. Unfortunately I can't find clarification on the otherwise visually identical tonearms. It appears the only difference was the bearing setup, knife edge for the DS and normal ball bearing for the HS. Not sure I buy that as I can't find actual pictures showing the difference but I'm not taking apart my tone arm so there ya go.
https://www.picclickimg.com/00/s/MT...wood-KP-KD-7010-990-9010-1100-Tonearm-_57.jpg
https://www.stereonet.com/forums/to...p-9010-direct-drive-semi-automatic-turntable/
My personal experience for what little it is worth is that my AT540ML and my generic 10gr headshell does okay on my concrete floors and floppy records but if you listen on a particularly warped record you can make out some wavering or as I like to think of it, extra vibrato. If the above is accurate it should be almost exactly a 8hz match. Not sure if it could be improved upon but I ordered a used Denon PCL-5 tonearm that weighs 6gr to see if it helps. I'll include some other options using the Denon(6g)or the nice AT-LH11H (11g) headshell I like because its got adjustable azimuth so no shimming. The AT-OC9XML is a bummer. Appears to be a forum favorite but it seems to be setup for modern turntables with lighter tonearms.
- Audio-Technica AT33xMLB: A perfect match with either headshell. It yields 10.4 Hz with the Denon and 9.4 Hz with the heavy AT headshell.
- Audio-Technica VM540ML: A good match only with the lighter Denon PCL-5 headshell (8.8 Hz). The AT headshell makes the arm too heavy (7.8 Hz).
- Ortofon Quintet Black S: A good match only with the lighter Denon PCL-5 headshell (8.8 Hz). The AT headshell drops it too low (7.9 Hz).
- Audio-Technica AT-OC9XML: Do not use. The compliance is far too high for this tonearm, resulting in poor resonance (6.1 Hz – 6.7 Hz) regardless of which headshell you use.
