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回覆 (1790): Cartridge Loading
careful - demagnetising and deguassing is very different.
daiwok
12-05-30
14:04:20
回覆 (1789): Cartridge Loading
i think i have posted this before but i post it again.  
http://sound.westhost.com/articles/cartridge-loading.html#s2  
____  
 
Dr. King,  
 
Thanks for posting this again. I did read it once when you post last time with quite a bit of confusion. I re-read it again with more understanding this time, it's a good article. In particular, the model about cartridge and phono.  
 
icefox
12-05-30
13:11:28
回覆 (1788): Cartridge Loading
Come to think about it, what are they (also the Cardas LP) suppose to demagnetize, the coil? The coils are usually made of copper, which is not magnetic in the first place! Strange!  
 
--------------------------------------------------------------  
I have the Cardas demagnetize LP also. It has to run on 45rpm, right? It only said the demag action is good for the whole system! I tried it many times and seems there is a tiny improvement in the treble after. I dont quite understand how it works and i suspect the reason for improvement if any has more to do with cartridge run in. The sweep frequency surely would soften the cartridge suspension and that may be the reason I heard a tiny improvement. Other than that, I am more leaning on Limage comments lor!  
bobui
12-05-30
12:25:13
回覆 (1787): Cartridge Loading
 
 
>Come to think about it, what are they (also the Cardas LP) suppose to demagnetize, the coil? The coils are usually made of copper, which is not magnetic in the first place! Strange!  
------  
you are getting better by day^-^<  
___________________________________________________________  
 
But the strange thing is that it ready did alter the sound, at least I felt it was for the better at the time.  
 
I suspect if it really does demagnetize, it may do it the magnets in the cartridge as well. However, if that really happened, I would expect the cartridge to sound much worst?!!!!  
 
thekong
12-05-30
11:53:46
回覆 (1786): Cartridge Loading
Come to think about it, what are they (also the Cardas LP) suppose to demagnetize, the coil? The coils are usually made of copper, which is not magnetic in the first place! Strange!  
------  
you are getting better by day^-^
drwkng
12-05-30
11:41:27
回覆 (1785): Cartridge Loading
make sure to downsize your pictures to reasonable level  
____  
 
Yes sir, sometime the fact is the google image I saw is small, when I grab the link and post it here...... it enlarges without control....... sorry gents, will try to be mindful in the future.
icefox
12-05-30
11:26:39
回覆 (1785): Cartridge Loading
 
>there is some device which help to "demagnitize" cartridge.  
________________________________________________  
Just another stupid gimmick. Luckily I only borrowed it for a trial. <  
__________________________________________________________  
 
I have also tried one of those a long time ago, and interestingly it did make a different for the better. At least that was how I felt at the time. However, I didn’t bother to do it regularly.  
 
Come to think about it, what are they (also the Cardas LP) suppose to demagnetize, the coil? The coils are usually made of copper, which is not magnetic in the first place! Strange!  
 
I suppose the same applies to demagnetizing LPs. While vinyl is not magnetic, some claims there are small amount of metal in the dye that makes LP black!  
 
 
thekong
12-05-30
11:19:08
回覆 (1784): Cartridge Loading
 
 
icefox,  
 
Please make sure to downsize your pictures to reasonable level. 2592 x 1936 is certainly far too big for comfort here.  
 
Everyone has to run to the end of the world to finish the sentence!  
 
 
limage
12-05-30
11:00:00
回覆 (1783): Cartridge Loading
 
the Old Fart is not doing too badly…..  
_______________________________  
 
Feikeung,  
 
I used to top the form across 5 classes in science subjects, in particular, physics and maths, when I was in secondary school.  
 
I went over to study literature because I was fed up with the teachers.  
 
limage
12-05-30
10:49:23
回覆 (1782): Cartridge Loading
 
 
there is some device which help to "demagnitize" cartridge.  
________________________________________________  
 
 
Just another stupid gimmick. Luckily I only borrowed it for a trial.  
 
limage
12-05-30
10:38:47
回覆 (1781): Cartridge Loading
A Fluke Digital Multi Meter  
 
I believe this is based on a simple measurement of the output voltage of the digital meter when switched to "Ohms" range. What this measurement misses is that this voltage is the result of a constant current source passed through a series resistor. In modern meters the series resistance is switchable to keep the divider value in the correct range for the meter circuitry.  
What this translates to is that the meter will put out a max voltage (for a Fluke it is 800mV) and a max current (for that meter it is 500 uA) but it will not put out both together. The problem with yesteryear analogy meter is because bothe the voltage and current were present with no limiter and at much high level.  
 
I cannot see how a current limited voltage of less than a volt / less than a milliamp can harm the coils of a cartridge. In the case of a high impedance cartridge the voltage limits the input power, in the case of a low impedance cartridge the current does.  
 
But the real question is. Under normal working condition, there really is no need to stick your DMM to measure the DC resistance of a cartridge. For me, I would simply trust the instruction manual and use the recommended as a guide line and choose the setting by final listening. And if you follow the 10X as a starting point, there is no reason you will go far off the chart for good sound.  
 
Van den hul is very good cartridge manufacturer for sure. The inconsistence issue should be the responsibility of Mr Hul company. Not in the hands of an average rich good guy who just want to pay for a quality product. It's not the given spec that is the problem, it's the particular product sample, right?    
 
bobui
12-05-30
09:57:24
回覆 (1781): typo
> in excess of the every thin gauge wires  
in excess of the very thin gauge wires  
 
> you hard-earned $$$  
your hard-earned $$$
feikeung
12-05-30
02:23:24
回覆 (1780): Cartridge Loading
The instantaneous state, rather than the steady state, of the electric circuit has to be looked at when accessing the effects of a voltage suddenly applied across a moving coil cartridge. What actually happens is that when the probes of a multi-meter are in contact with the leads, a pulse (step function) is generated. The surge results in an instantaneous current through the coils, which can be envisaged as a resistor and inductor in series, in excess of the every thin gauge wires in the windings can handle. Here goes the 2 months of you hard-earned $$$.  
 
Also, the pulse may induce a magnetic field strong enough to realign the orientations of the magnetic particles, rendering your beloved DECCA London nothing more than a paper weight on your desk.  
 
Being an artsie and having never taken differential equations at college, I assume, the Old Fart is not doing too badly…..  
 
feikeung
12-05-30
01:53:57
回覆 (1779): Cartridge Loading
Cardas is certainly one. I don't have that but I think my Telarc Omnidisc has that demagnetizing track too..
icefox
12-05-29
23:51:03
回覆 (1778): Cartridge Loading
朋友 you mean the Cardas Sweep record for deguassing the whole system starting from the cartridge all the way to the speakers ? by chance I have this record 8^)
daiwok
12-05-29
23:42:20
回覆 (1777): Cartridge Loading
Also, I recall seeing some Test Records would have tracks for cartridge demagnetization. .......... would that be useful?
icefox
12-05-29
22:11:03
回覆 (1776): Cartridge Loading
NEVER MEASURE CARTRIDGES WITH MULTI METERS, FLUKE or NOT.  
___  
 
Dear Limage, you raise an interesting point - magnetization of cartridge. I recall in the good old days, there is some device which help to "demagnitize" cartridge. What is the deal of those offerings? I suppose you tried those back then when you are young and dumb. I do not recall your use of such device in your very displined approach to LP playback. I suppose they are not really useful. Any sharing on this respect?  
 
icefox
12-05-29
21:48:23
回覆 (1775): Cartridge Loading
 
 
Gentlemen,  
 
Be it a warning in case some buddies here can’t tell AC from DC.  
 
 
NEVER MEASURE CARTRIDGES WITH MULTI METERS, FLUKE or NOT.  
 
 
I did that when I was young and dumb. It cost me two month’s pay. Even if the coil survives, it would be irrevocably magnetized. It will never sound the same as it should.  
 
Well, to determine the optimum loading, why not use your own ears. They are so handy!  
 
 
limage
12-05-29
20:25:56
回覆 (1774): Cartridge Loading
 
>Here is the specfication for VDH Colibri. The internal impedance is written clear for the three different versions and all recommended load is roughly 10X or higher. Right? <  
_____________________________________________________________  
 
As the owner of 2 Colibris, I would not trust these general specs mentioned. The specs written on the individual boxes are more believable, but still I would be skeptical.  
 
The truth is nearly every Colibri has different specs, even different length of cantilevers. The coils are supposed to be hand wound by VDH himself, so every unit has slightly, or not so slightly, differences in output. :-)  
 
According to Ralph Karsten of Atmosphere, the cartridge should perform the same no matter it is 1KΩ or 47KΩ (as long as it is at least 10X the impedance of the cartridge) if the phono stage can handle the RF.  
 
The reason a cartridge manufacturer recommend a lower loading could be that he afraid his cartridge would sound bad with a phono stage that could be overloaded by RF at 47KΩ  
 
thekong
12-05-29
19:18:29
回覆 (1773): Cartridge Loading
Impedance is the ratio of the voltage to the current in an (AC) circuit Impedance in an AC circuits contain both magnitude and phase, unlike resistance which only has magnitude. When a circuit is in DC, there is no distinction between impedance and resistance; the resistance can be thought of as impedance with zero phase angle.  
 
 
So the answer is yes, please keep in mind that the DC rsistance measure is an indication because it does not take into account the AC elements.  
 
bobui
12-05-29
17:52:57
回覆 (1772): Cartridge Loading
Thats right and it only gives a indication!
bobui
12-05-29
17:42:11
回覆 (1771): Cartridge Loading
An your measured figure on an 8 ohms speaker unit would mostly be around 5 to 7 ohms.  
-----  
you are measuring the dc resistance of the coil. this is not speaker impedance!
drwkng
12-05-29
17:37:48
回覆 (1770): Cartridge Loading
Gents, I do agree with bobui in a certain way. Measurements are good, to the least it serve us with some info, better than none in this circumstances. Problem is if we couldn't manipulate with the cart spec, at best our fate depends on the mercy of our phono with hope that selections are adequately provided.  
 
 
DMM would not damage cartridge while analogue one might  
__________________________________________________________  
 
No problem la, just get two carts, one to be sacrificed for measurement, the other for real use. 七盤八臂十六頭, the reason why carts double that of arms is half of the carts were dead after measuring the impedance. 乜冇人同你講過咩?
Derek2A3
12-05-29
17:37:02
回覆 (1770): Cartridge Loading
how much difference would that be between impedance and DC resistant in a cartridge?  
-------------------------------------------------------------------------  
Thats a good question.  
 
Have you ever measure the DC resistance of an 8 ohms speaker unit? Well, try if you have one and if yours is a Fluke DMM. As icefox has pointed out. It wont blow your speaker into smoke. And will not turn your cartridge into a lovely looking sculpture either.  
 
An your measured figure on an 8 ohms speaker unit would mostly be around 5 to 7 ohms. A little lower than the specify 8 ohms. I think that is one of the reason why some pro guys insist on getting an accurate measure which i think is a must if you are a designer.  
 
bobui
12-05-29
17:25:48
回覆 (1769): Cartridge Loading
Here is the specfication for VDH Colibri. The internal impedance is written clear for the three different versions and all recommended load is roughly 10X or higher. Right?  
 
So the question is what is the best load? The best load does dedpending on the various factors MC cow, the preamp, cable length etc. but I can assure you that it wont be 1.5X because it just not electrical correct.
bobui
12-05-29
17:09:19
回覆 (1767): Cartridge Loading
ave somewhere in his workshop a unit of those high end Agilent LCR bridges like the E4980A which could help us in measuring the "impedence" of cartridge. It may also help to measure capacitance of our DIY phono cable......  
-------  
i think i have posted this before but i post it again.  
http://sound.westhost.com/articles/cartridge-loading.html#s2  
 
drwkng
12-05-29
17:09:06
回覆 (1769): Cartridge Loading
 
>kong, you mean Fluke, right? ^__^ <  
_______________________________________  
 
Ah yes, Fluke! You can tell I am no techie at all :-)  
 
thekong
12-05-29
17:02:45
回覆 (1768): Cartridge Loading
flute meter  
————————  
kong, you mean Fluke, right? ^__^  
 
DMM would not damage cartridge while analogue one might....
icefox
12-05-29
16:37:43
回覆 (1767): Cartridge Loading
how do you measure "cartridge internal impedance  
----------------------------------------------------------------------  
I don't. I simply follow manufacturer instruction manual. The internal impedance is mostly written clear in the manual. If output impedance varies with different frequency. Would you simply take the average? If not, which measured figure you want to take?  
 
The question is why on earth do you need to have a precisely measured cartridge internal impedance down to two decimal of 99.9999999% accuracy for your cartridge loading? The impedance varies with frequency anyway, right. The 10X is a general guide line, not a must or you eill die. But if the loading is lower or only a a few ohms higher than the cartridge internal impedance, you will have insertion lose across the internal resistance of the source.
bobui
12-05-29
16:21:28
回覆 (1767): Cartridge Loading
 
>how do you measure "cartridge internal impedance"?<  
____________________________________________________  
 
As it is basically just the coil, how much difference would that be between impedance and DC resistant in a cartridge? And frequency dependent?  
 
I have once measured a ClearAudio cartridge with a normal flute meter, and it showed 50Ω  
 
Now, come to think about it, how much voltage/current would it take to fry the coil of a MC cartridge, considering the thin wire in use? Would a flute meter do any damage, at least for the more fragile ones?  
 
I seem to remember reading somewhere that the older meters with “needle pointers” had higher output voltage than the newer digital ones, is there any truth to it?  
 
thekong
12-05-29
16:15:43
回覆 (1766): Cartridge Loading
My rule of 拇指!  
Loading should be at least 10X of the cartridge internal impedance. Higher is all fine, any lower than 10X is not IDEAL lor.  
______  
 
bobui........ how do you measure "cartridge internal impedance"? I think the value also vary with the measuring frequency........  
 
I have always been wishfully thinking that Dr. King (or Lord CP) may have somewhere in his workshop a unit of those high end Agilent LCR bridges like the E4980A which could help us in measuring the "impedence" of cartridge. It may also help to measure capacitance of our DIY phono cable......  
 
May I know if any inmates here have and access to one those half decent LCR bridge? I have some experiments in mind.  
icefox
12-05-29
15:50:24
回覆 (1765): Cartridge Loading
Glad to see an active discussion on this topic....... this is one of the blackest/darkest magic in the vinyl art.  
 
This discussion kind of reminding me the Audiogon MM guru mentioned about the need for 100K loading on those Acutex MM cart.  
 
I am glad that my KAB phono provide with me an easy front panel access to play with cartridge loading........
icefox
12-05-29
15:40:36
回覆 (1764): Cartridge Loading
in 2008's Vacuum State newsletter, Allen Wright wrote:  
Phono cartridge loading  
If there is one thing that really annoys me, it’s the unthinking  
insistence of most moving coil cartridge users that the cartridge needs  
to be heavily loaded down to sound at it’s best.  
I have heard of people loading a low output MC with with little as 10  
ohms—to me this always kills the life and dynamics of any cartridge.  
Most manufacturers (and experts) recommend a wide range of loads  
for their MCs—but in our experience many (but not all) MCs sound  
far more alive with a 47kΩ loading that’s normally used with MMs!  
And all the five cartridge manufacturers that I know personally, all  
have told me privately that they use 47k on their cartridges at home.  
I believe the main problem originates in that many MCs have a high  
frequency resonance, and this overloads certain MC phono stages—  
not so our designs. With around 40dB of overload margin, even the  
most resonate of cartridges cause no problems at all.  
So please do not automatically load down (and perhaps choke) your  
wonderful cartridge—try 47kΩ as well as the normal lower values,  
and see which you really like for music—there may be a happy  
surprise in store for you.
scallywag
12-05-29
14:12:49
回覆 (1764): Cartridge Loading
cartridge loading  
------------------------  
Interesting read. Thanks! I like the Allen Wright thread.  
 
My rule of 拇指!  
Loading should be at least 10X of the cartridge internal impedance. Higher is all fine, any lower than 10X is not IDEAL lor.  
 
我的規則 of thumb!  
A 50 ohm source would drive a 10K load perfectly even via a long cable. Problems arise only if the mismatch loads the source. For example a 10K source driving a 600 ohm load would have considerable insertion loss because most of the signal voltage would be lost across the internal (10K) resistance of the source. A 600 ohm source driving a 10K load is fine.  
 
bobui
12-05-29
14:12:36
回覆 (1763): Cartridge Loading
 
Here is an interesting thread on Audiogon, with discussions on cartridge loading in the later part of the thread.  
 
A number of cartridge and phono designers (J Carr of Lyra, Ralph Karsten of Atmasphere, and the late Allen Wright of Vacuum State) all seem to agree that low output MC cartridges should ideally be loaded at 47K.  
 
Ralph Karstan stated the reason why 47K sounded thin in some system was because the phono stages couldn’t handle, and being overload, by RF.  
 
http://forum.audiogon.com/cgi-bin/fr.pl?eanlg&1335732158&&&/Tube-Preamp-Paired-with-Tube-Phono-Stage
thekong
12-05-29
13:17:29
回覆 (1762): Eye candies idler wheel TT
you need a barn, D :)
Willleung
12-05-28
00:16:26
回覆 (1761): Eye candies idler wheel TT
only idlers ! and that's a double dose of EMT 927 !
daiwok
12-05-27
21:48:00
回覆 (1760): Eye candies idler wheel TT
I missed the Lenco meet this time and what a party !  
 
daiwok
12-05-27
21:42:35
回覆 (1759): Eye candies idler wheel TT
Art Dudley trying the Ortfon Xpression on the Schick Stick......  
 
http://www.stereophile.com/content/listening-110
icefox
12-05-26
18:44:21
回覆 (1758): Eye candies idler wheel TT
number found:  
 
http://www.discogs.com/groups/topic/88903  
 
Cheers, W
Willleung
12-05-23
21:37:51