Best way is by using a series resistor and a generator. You'll need a scope or AC voltmeter with a low C (10x) probe. Measure the f3 as you change the frequency, then calculate the capacitance.
Depending on the components you use, you might have to temporarily get rid of the 47k input resistor and sub in a 1M, just to make the math easier.
Depending on the components you use, you might have to temporarily get rid of the 47k input resistor and sub in a 1M, just to make the math easier.
Hi Sy
OK, let me piece these instructions together in my head.
First, is what you propose a measurement for all of the capacitance?
Meaning, you apply the generator, resister and scope to one end of the turntable plugged into the preamp?
That is, everything is in place except the cartridge and you apply the generator/resister
to a pair of cartridge clips (signal & ground) and then measure with the scope?
That way the measurement includes the tonearm wiring and the input to the preamp.
I guess you could measure the turntable wiring seperately from the input capacitance of the preamp.
Am I on the right track here?
Curt
OK, let me piece these instructions together in my head.
First, is what you propose a measurement for all of the capacitance?
Meaning, you apply the generator, resister and scope to one end of the turntable plugged into the preamp?
That is, everything is in place except the cartridge and you apply the generator/resister
to a pair of cartridge clips (signal & ground) and then measure with the scope?
That way the measurement includes the tonearm wiring and the input to the preamp.
I guess you could measure the turntable wiring seperately from the input capacitance of the preamp.
Am I on the right track here?
Curt
My brothers B&O cartridge on his early B&O turntable sounded profoundly better than my Shure M75ED on an old Empire turntable, and I always wondered why the difference was so big. The B&O cartridge only fit their particular turntable (their first one in about 1973), and the audio output cables were not detachable, so the cartridge had a better chance of knowing what the capacitive loading might be. The Shure cartridge I had was a "stand alone" product that was sold separately and designed to be used on any number of tonearms with who knows what cable capacitance.
To cut to the chase, If you don't calibrate this capacitive loading of a MM cartridge using a professional test record, then it's a crap shoot whether your high end frequency response will drop dead early, or have a big spike in amplitude at the high end. MC has such a low output impedance that it's not going to be nearly as sensitive to capacitive loading.
To cut to the chase, If you don't calibrate this capacitive loading of a MM cartridge using a professional test record, then it's a crap shoot whether your high end frequency response will drop dead early, or have a big spike in amplitude at the high end. MC has such a low output impedance that it's not going to be nearly as sensitive to capacitive loading.
In my experience the load capacitance can only be adjusted by listening. First, almost all cartridges are not flat in their frequency response; e.g. like very most MCs are independent of the loading.
2nd, load capacitance changes of 50pF are very clearly and easily hearable, but do not affect the frequency response so that the optimum point becomes obvious.
EDIT: B&O's MI cartridges enjoyed an excellent reputation, so while I never heard one myself I'm not suprised you liked it.
2nd, load capacitance changes of 50pF are very clearly and easily hearable, but do not affect the frequency response so that the optimum point becomes obvious.
EDIT: B&O's MI cartridges enjoyed an excellent reputation, so while I never heard one myself I'm not suprised you liked it.
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Variable resistive input load combines for flexibility too. Few old Japanese upper range gear had a small pot for that at the back panel. Easy to implement that feature in DIY MM phonos.
Curt, without a C bridge, you have to do things indirectly. Substitute a 1M resistor for the usual 47k input resistor for simplicity. If you want to measure the whole shebang, disconnect the cartridge.
At the cartridge clip end, put a 100k series resistor in the "hot" lead. Attach a square wave generator to the 100k resistor and the "cold" lead. Keep the amplitude low! 30mV is a reasonable compromise, but if your stage has good overload margins, you can go higher.
With a low C probe (like a 10x), look at the square wave at the input. Measure rise time- if you use 10% - 90%, that time = 2.2RC, where R is your series R value, then you can back into the C value. This isn't perfectly accurate because of the 1M loading, but it's close.
Likewise, you can measure f3 (the -3dB down point) at the input using a sine wave generator in the same setup. For 100pF, the f3 will be roughly 16kHz, 200pF will be 8kHz, and so forth.
At the cartridge clip end, put a 100k series resistor in the "hot" lead. Attach a square wave generator to the 100k resistor and the "cold" lead. Keep the amplitude low! 30mV is a reasonable compromise, but if your stage has good overload margins, you can go higher.
With a low C probe (like a 10x), look at the square wave at the input. Measure rise time- if you use 10% - 90%, that time = 2.2RC, where R is your series R value, then you can back into the C value. This isn't perfectly accurate because of the 1M loading, but it's close.
Likewise, you can measure f3 (the -3dB down point) at the input using a sine wave generator in the same setup. For 100pF, the f3 will be roughly 16kHz, 200pF will be 8kHz, and so forth.
Frequency response and (to a smaller extent) level and noise. Here's an example using the 150MLX showing change in frequency response and level by changing from 47k to 20k.
Not sure what Sy was talking about. Measuring the cables reactance without the loading as it will be in actual use may be pretty different. In many cases varying the load resistance away from the nominal 47Kohms might be helpful, but I'd be careful with that. One RIAA preamp project I saw somewhere had a tuning cap out of an old radio that allowed you to vary the capactance loading of the cartridge. The variable cap would add to the capacitance of the cables. I don't see how you can judge a MM cartridge unless you've calibrated this loading effect using a professional test record with pink noise or swept sinewave.
My personal view is that there are good and bad examples of all cartridge types. Except for MI - never heard a bad MI cartridge!! I've used valve pre-amps for a long time, so have shunned MC until recently - which is a real shame because they can sound nice. but my favourite at the moment is WIN strain gauge.
MM - Shure V15 is extremely accurate, but has no soul. Too clinical (IMHO). Garrott P77 is not as accurate, but nicer sounding.
MI - I admit that i love Grados. I've had 2 wood bodies - platinum and sonata - and they both sing. I've got an Amber Tribute (an Australian branded Grado Signature) and its very ncie as well. I recently bought a real Signature TLZ but haven't had a chance to listen to it yet.
MC - ZYX is good. I've got a R100 and Sonic Purity Ayame (re-badged Universe). They both sound good, but there's too much hum from my valve pre. I've got some transformers on the way from eBay, and hope to address this soon. but the best MC cartridger I've heard - a mate of mine has a Monster Alpha, and a high gain s-s pre. Even with transistors (and no hum) this hits every thing else out of the park. The Monster is made by ZYX I'm pretty sure.
I had an AT OC9. They have a good rep. I found it cold and uninviting.
As for high output types - I do have a Sumiko Blue Point. Haven't listened to it in about 18 years and my memory is too hazy. My (then) 1 year old managed to get up close to my TT and whacked the arm, bending the cantilever in the process. So, haven't been able to re-appraise this one.
Strain Gauge. I've got a WIN, with a new boron cantilever. Its sublime. The original op-amp based head amp is a bit ropey, I've built a discrete Jfet amp and its what i currently listen to. My mate has a Panasonic, its very good as well, but lower gain.
So what is best? There are so many variables. As stated, my valve pre does not allow me to extract the best from my mc cartridges. I suspect that my arm (Souther linear tracker) is also not well suited to mc. So in reposne to OP - yes there is a real opportunity to re-appraise mm. However, every cartridge works best in a particular arm, with a particular gain stage. Its really hard to compare cartridges at home unless you also have different arms and pre-amps. Witness my views on mc - in my system they are OK but no better than Grado, but in my mate's system, mc rules - better than anything I can achieve (hmmm, maybe i need to replicate his system then). No such thing as best, only what is best in your system.
MM - Shure V15 is extremely accurate, but has no soul. Too clinical (IMHO). Garrott P77 is not as accurate, but nicer sounding.
MI - I admit that i love Grados. I've had 2 wood bodies - platinum and sonata - and they both sing. I've got an Amber Tribute (an Australian branded Grado Signature) and its very ncie as well. I recently bought a real Signature TLZ but haven't had a chance to listen to it yet.
MC - ZYX is good. I've got a R100 and Sonic Purity Ayame (re-badged Universe). They both sound good, but there's too much hum from my valve pre. I've got some transformers on the way from eBay, and hope to address this soon. but the best MC cartridger I've heard - a mate of mine has a Monster Alpha, and a high gain s-s pre. Even with transistors (and no hum) this hits every thing else out of the park. The Monster is made by ZYX I'm pretty sure.
I had an AT OC9. They have a good rep. I found it cold and uninviting.
As for high output types - I do have a Sumiko Blue Point. Haven't listened to it in about 18 years and my memory is too hazy. My (then) 1 year old managed to get up close to my TT and whacked the arm, bending the cantilever in the process. So, haven't been able to re-appraise this one.
Strain Gauge. I've got a WIN, with a new boron cantilever. Its sublime. The original op-amp based head amp is a bit ropey, I've built a discrete Jfet amp and its what i currently listen to. My mate has a Panasonic, its very good as well, but lower gain.
So what is best? There are so many variables. As stated, my valve pre does not allow me to extract the best from my mc cartridges. I suspect that my arm (Souther linear tracker) is also not well suited to mc. So in reposne to OP - yes there is a real opportunity to re-appraise mm. However, every cartridge works best in a particular arm, with a particular gain stage. Its really hard to compare cartridges at home unless you also have different arms and pre-amps. Witness my views on mc - in my system they are OK but no better than Grado, but in my mate's system, mc rules - better than anything I can achieve (hmmm, maybe i need to replicate his system then). No such thing as best, only what is best in your system.
well, it's always handy to know where you are starting. SY's method allows you to measure the capacitance of the cabling AND input stage of your pre. gives you the baseline for when you have no added capacitance. Pretty useful bit of information.
Are you saying you prefer a euphonic cartridge? To possibly misquote the late J Gordon Holt 'neutrality: the thing everyone says they want until they get it'. I'm not going to argue with anyones preferences, but interested that you infer the V15 is the most neutral cartridge you have heard.
The VMR (microridge) version was quite good, but a little "wispy" at the top end, and had fantastic tracking ability.
The spherical tip version sounded very similar, but was a little dull in the top octave.
Did I say that I prefer a euphonic cartridge? I only said that I prefer the garrott to the shure. Is the garrott more euphonic than the Shure? Well that's a bit subjective for me to answer. But if euphonoic means pleassant sounding, than I would rather have a euphonic cartridge than a dischordant cartridge!!
But maybe you are right. I've never liked CD much (you can tell by the number of cartridges i've owned over the years). CD is more accurate than vinyl, yet many people still prefer vinyl. Is that becuase vinyl is more euphonic, even if you've got a Shure on your arm? or is it because vinyl has an extended frequency response without a brick wall filter at 22kHz? Is it becasue vinyl has an infinite sample rate compared to 44.1khz? I dunno, I don't get too analytical, I like what i like and don't worry too much about why I like it. That's why i've listened to so many cartidges. i don't bother about specs, or about reviews - i listen to it, and if I like it then that's good enough for me.
I am an EE by trade, and have designed all my own amps - power amps, active cross overs, preamps. I can be analytical when i need eg designing circuits. i just don't feel the need to be analytical when I listen to music.
@hazard500 wasn't inferring anything, but trying to understand if by 'accurate' and 'clinical' you meant that the V15 was actually neutral but not what you wanted.
I probably ended up with a vinyl from end that works for me more by luck than judgement. but now i am planning a second turntable (a kenwood DD) that I have inherited I get a change to build something that is wrong according to everything the hifi press were pushing when I was building my main rig. What I have learned in this thread is that, somewhere in the late 70s/early 80s the UK the press stopped understanding how to set up systems for MM.
and FWIW it just amazes me how good vinyl can sound given you are dragging a rock through plastic. really shouldn't work well at all.
I probably ended up with a vinyl from end that works for me more by luck than judgement. but now i am planning a second turntable (a kenwood DD) that I have inherited I get a change to build something that is wrong according to everything the hifi press were pushing when I was building my main rig. What I have learned in this thread is that, somewhere in the late 70s/early 80s the UK the press stopped understanding how to set up systems for MM.
and FWIW it just amazes me how good vinyl can sound given you are dragging a rock through plastic. really shouldn't work well at all.
What's wrong with that? If it means pleasant sounding to MY ears then I prefer euphonic equipment.
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