Ed why don't you put the same NPO caps Samuel used in your bridge so we can compare and discuss? He found nothing of note.
BTW Ed your're doing it again, putting up plots with no detailed description of exactly the stimulus, circuit configuration, levels, where the output is taken, etc.
Scott,
Exactly the same bridge as with resistors only 10 of the same model capacitors. Driving signal is 10 volt sine wave. There is one big caveat and when next I have time I will verify that it can cause a false high reading that did not occur with resistors.
There is nothing new or mystical. The part of interest is how different capacitors perform.
No trimmer resistor is used to balance the bridge instead it is done by matching test capacitors values.
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You got the issue. The output impedance is 20 ohms. So the rise in distortion is reasonably from the generator. As is shown by the drop in fundamental level. But as the bridge nulls the fundamental it should also null the harmonics so a moderately low distortion audio power amplifier can be used. But the test setup should yield good comparisons between batches of capacitors at 500 hertz as the fundamental and third harmonic seem to be the same as 50 hertz. Nice thing is it reduces the total runs required.
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Ed just to avoid past misunderstandings we need to see every component specified in detail. That is what is providing the stimulus, etc. so that the experiment is repeatable.
I haven't exactly figured this one out but...
I use a DD TT. That makes it somewhat like the Technics. Hear's the kicker, it sounds bad unless I have the power conditioned going into it.... The Technics perhaps share a similar fate. Because otherwise how are the simple measurements not worth anything with good wow, flutter, speed? Sure if you have a Thorens in a massive new plinth you have an advantage, but you didn't mention one.
Ed this is all well and good but Samuel G showed some measurements of easily affordable caps for all the applications that I'm interested in. Are you challenging his work or just showing us things that don't work?
I can't find CGA5L2COGAH104J160AA, maybe a typo? What is the use case for 100x 0.1uF NP0 anyway?
FWIW Bruce Hofer claims that distortion is worse with low voltage C0G/NP0 and recommends avoiding the 25V parts completely. 50 is definitely higher but there are much higher voltage parts available if you can tolerate the physical size.
No magic on all capacitors the higher voltage parts are better. Thicker dielectric helps reduce distortions.
All tests are aimed to be with a useful to audio value which really starts around 1 uF but for eq use often lower. So I uF seems a reasonable test value. So as ten are needed for the test using 100 of the .1 uF is a good choice of easily available values.
These came from Digikey.
All tests are aimed to be with a useful to audio value which really starts around 1 uF but for eq use often lower. So I uF seems a reasonable test value. So as ten are needed for the test using 100 of the .1 uF is a good choice of easily available values.
These came from Digikey.
Hi Destroyer OS,
I don't know about the power supply. It shouldn't make that kind of difference to what you are hearing for speed stability. Keep in mind that the AC power is stepped down, rectified and applied as needed to the motor. The platter in your system is part of the motor. I think the important thing might be rotating mass vs how compliant the connection between the driving force and the platter is. In your case, a weak motor drive signal would probably improve the flutter aspect, but this also depends a great deal on the bearings. It would increase the time to reach playing speed, but it's the same with a belt drive. Note that Thorens tables use a clutch (a real felt and platter clutch) between the motor and the pulley for the belt. The belt being very compliant as well.
The direct drive tables were marketed on how fast they came up to speed, but that works against you when things are turning in a steady state speed. This is where the term "cogging" comes into play. To come up to speed rapidly, the rotating mass has to be reduced, or the motor assy must get larger and more powerful. That makes the influence of the motor assy felt more. About opposite of what you would want once at speed.
All my tables were stock except for the suspension. Bearings were all factory. When I got my first TD-125 MKII, what blew me away was the absence of any kind of rumble. I wasn't even aware my earlier tables (some DD) had this problem until I heard something that didn't have the problem. From that point forward, the sanely high mass platter and decoupled motor was the only way to go. Every table with less good bearings or too tight motor coupling is pretty obvious once you get use to very low levels of rumble. This is where the older TD-124 and other similar tables apparently shine. I had a TD-124 and didn't like it too much. With the extra work put into these modern takes on it, I guess they are even less noisy than my tables have been. Something I have to experience for myself, but the cost of admission is a might high for me. The move from the Technics to a Thorens TD-125 MKII or TD-126 MKII or MKIII is a lot lower. I love the TD-126 MKII set up so far. It has auto-lift at the end of the record. Very handy. The very low mass factory arm is a perfect match for the Ortofon 540 MKII I have on it right now. That combination makes music.
I almost forgot one fabulous upgrade I made for both tables. I installed a "Platter Matter", which is a very compliant mat that sticks to the platter and the record. It absorbs most vibration from the stylus and anywhere else around. I've never before heard such "silence between the notes" before. I sure wish they made them new again. I had one I bought in the 70's and located another a few months ago. This will improve your table as well.
-Chris
I don't know about the power supply. It shouldn't make that kind of difference to what you are hearing for speed stability. Keep in mind that the AC power is stepped down, rectified and applied as needed to the motor. The platter in your system is part of the motor. I think the important thing might be rotating mass vs how compliant the connection between the driving force and the platter is. In your case, a weak motor drive signal would probably improve the flutter aspect, but this also depends a great deal on the bearings. It would increase the time to reach playing speed, but it's the same with a belt drive. Note that Thorens tables use a clutch (a real felt and platter clutch) between the motor and the pulley for the belt. The belt being very compliant as well.
The direct drive tables were marketed on how fast they came up to speed, but that works against you when things are turning in a steady state speed. This is where the term "cogging" comes into play. To come up to speed rapidly, the rotating mass has to be reduced, or the motor assy must get larger and more powerful. That makes the influence of the motor assy felt more. About opposite of what you would want once at speed.
All my tables were stock except for the suspension. Bearings were all factory. When I got my first TD-125 MKII, what blew me away was the absence of any kind of rumble. I wasn't even aware my earlier tables (some DD) had this problem until I heard something that didn't have the problem. From that point forward, the sanely high mass platter and decoupled motor was the only way to go. Every table with less good bearings or too tight motor coupling is pretty obvious once you get use to very low levels of rumble. This is where the older TD-124 and other similar tables apparently shine. I had a TD-124 and didn't like it too much. With the extra work put into these modern takes on it, I guess they are even less noisy than my tables have been. Something I have to experience for myself, but the cost of admission is a might high for me. The move from the Technics to a Thorens TD-125 MKII or TD-126 MKII or MKIII is a lot lower. I love the TD-126 MKII set up so far. It has auto-lift at the end of the record. Very handy. The very low mass factory arm is a perfect match for the Ortofon 540 MKII I have on it right now. That combination makes music.
I almost forgot one fabulous upgrade I made for both tables. I installed a "Platter Matter", which is a very compliant mat that sticks to the platter and the record. It absorbs most vibration from the stylus and anywhere else around. I've never before heard such "silence between the notes" before. I sure wish they made them new again. I had one I bought in the 70's and located another a few months ago. This will improve your table as well.
-Chris
@Billshurv:
Interesting that you mentioned the SP-10. Revered for its phono section.
What were you looking to exchange for one of these? As I have one, it has the factory upgrade to MKII status.
These aren't cheap and they are two complete chassis, A power supply and its pre amp. PM me if you are have something serious to trade of similar value.
Cheers,
Interesting that you mentioned the SP-10. Revered for its phono section.
What were you looking to exchange for one of these? As I have one, it has the factory upgrade to MKII status.
These aren't cheap and they are two complete chassis, A power supply and its pre amp. PM me if you are have something serious to trade of similar value.
Cheers,
I guess my point is that you're picking almost the lowest voltage and highest capacitance vs volume parts available to test. Did you do the same for the film caps you've tested? We already know from more than one source that they don't show much if any measurable distortion in their intended use. I have no idea why anyone would try to create a coupling cap or something out of 10s of C0G caps. At that point you are probably in metallized polypropylene territory, volumetrically speaking.
All caps in the test are 1 uF at as close to 63 VDC as available. Distortion of course will drop for all of them as voltage rating increases.
RNM it is the classic Wheatstone bridge. Just no adjustment, equal capacitance in each leg, but unequal voltage rating for the device under test.
Derfy, the issue is basic (not the same a simple.)
C = q/V. C dv/dt + V dc/dt = i. In the series parallel combination each equal value capacitor has the same value so V = 1/2 and dc (a function) will have a different value than a solo C. If dc has half the value the each capacitor in the four pack will produce distortion of 1/2 x 1/2 or 1/4 of a solo unit at full voltage. Thus the two in series of the four pack will produce 1/2 the distortion. Now when you parallel two of the series twofers to make the four pack the combined distortion does not increase, however any internal issues that can be treated as noise will drop by the square root of 2.
As you have two sides of the bridge that will double the distortion difference from the 1/2 that each 4-1 pair (side) will produce. So you end up able to see the distortion clearly.
Note what also falls out is that the C dv/dt component should cancel to the limit of the 4C-1C match. Note the even if dv is a series of sines (AKA distortion) they should also cancel. Thus you can measure passive component distortion below the test generator normal limits.
Now that I believe is as simple as I can make it. Even so almost no one gets it. Typical errors are to use a reference part instead of the Gang of Four. Thus calibration is lost. By shuffling around parts in where they are in the gang of ten you can tweak in on each unit part's contribution.
The technique does require very similar parts.
OK THx. I have several 1mfd hermetically sealed Teflon caps which could make a nice bridge also.
BTW - I first reported that higher voltage caps were better decades ago but it was derived from Z vs freq measurements.
Espec for polar caps. Along with that is the Temp rating --- 85C or 105C. The 105C always measured better, also.
Many basic tests can be done to high degree with basic test equipment.
Thx-RNMarsh
BTW - I first reported that higher voltage caps were better decades ago but it was derived from Z vs freq measurements.
Espec for polar caps. Along with that is the Temp rating --- 85C or 105C. The 105C always measured better, also.
Many basic tests can be done to high degree with basic test equipment.
Thx-RNMarsh
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Gosh you are slumming it now. Nice rig.
Depends of the view point.
I had the lucky situation with both TT on the same stereo equipment, since the FM 222 Phono has 2 inputs and a switch.
In the end, without any measurings i found that the G R had really a lower mechanic noise floor than the 930, but the 930 rig has more dynamics, punch, impact or however you will name it. In short , the 930 combo provide for me more emotions while listening music.
Imho the 930 looks not really good, my wife hate it, but sonically i prefer this old machine.
The real advantage of the 930 next the sound is that there is no Software and no electronics which could fail, the G R is no more supported by the Maker since many years and i am an old fashioned user, the choice was not so hard.
No need to discuss unobtainium parts nor updates nor electronic parts aging and so on. Just find a good mechanic making the parts you need and all is fine for me.
Also my tonearm has no electronics, but tracking error angle is not worth any discussion.
The cartdrige uses spheric styli, not perfect, but not introducing more uncontrollable distortions given by any other stylus shape.
In the end i just have to clean the stylus all 5-10 hours and the rest is pleasure listening music. But i must admit, reading this Thread is also a lot of fun .
regards
Frank
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