Sumiko Blue Point HOMC with Heavy Wear
Or, why you need measurements to buy second hand if you don't have a good microscope
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I recently purchased a used Sumiko Blue Point that was described to be in excellent condition even after numerous questions. I told the guy I can gauge wear with a microscope and even showed him a few examples. Not to worry he said, if I could "determine" any wear I was free to return.
Lo and behold: it's badly worn.
As the primary owner he must have known. This is hundreds and hundreds of hours of wear. People really will sell anything and see what sticks as most people will not know better. It's incredibly hard to prove wear without evidence. More, ask yourself, how much is acceptable before I request a return? Luckily I have a good microscope, but I also have measurements. I use a beater CBS record for these types of cartridges. This is a very good reason to get yourself an extra, cheaper test record. I may as well not completely waste my time despite my annoyance:
Das Sumiko Blue Point No 2 ist das kleinste Moving Coil- (MC-) System des US-amerikanischen Highend-
www.lowbeats.de
Hi-Fi World, 1993-03, p-mount version review measurement
Notes
- These were taken on a CBS STR-100 that I to adjusted to CA-TRS-100's FR
- Sumiko recommends MM loading (47kΩ)
- Obviously the pictures tell us this elliptical stylus is worn to hell
- But the distortion measurements tell the same story
- With new cartridges 2H gets down to -40 dB at 1kHz on the CBS STR-100, further on CA-TRS-1007
- See the Shure V15 V-MR results to better see the differences between the test records
- Here we see it lost around 10 dB at 1kHz --that's the effect of wear
- Results worse than -20 dB between 5-10kHz set off my alarm
- Clearly the results above 10kHz are the most conclusive evidence of wear
- At this point I have not seen strong evidence that FR changes much with wear
- The Lowbeats measurements of the Blue Point #2 show a similar rise
- Generally, MC cartridges slope upwards
- Note that crosstalk seems to improve with wear from what I have seen
- But CBS STR-100 is limited so don't go by these results either way
So not a complete loss as I was able to measure it. If someone posts results for one in better condition we can compare. More importantly, it has satiated my curiosity regarding the cartridge!