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Old 24th March 2012, 08:10 AM   #21631
kamis is offline kamis  Serbia
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Quote:
Originally Posted by Wavebourn View Post
I use this kind of resistors routinely (2W pictured):

Click the image to open in full size.
Following your advice on another forum, I bought in a local electronic parts store many values of MLT-1 and some MLT-2 resistors which are very cheap.
They are all produced in 1988. I know that they are 5% metal film types,but temperature co. value is not published.I have not yet tried them in my circuits.
What is so special about MLT resistors?
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Old 24th March 2012, 09:16 AM   #21632
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Tesla metalized resistors, high precision types TR161 - TR164 (0.25 - 1W), were produced in 5 categories of temperature coefficient.

0 ... 200ppm
1 ... 100ppm
2 ... 50ppm
3 ... 25ppm
4 ... 15ppm

http://katalogy.ic.cz/TR164.html
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Old 24th March 2012, 09:22 AM   #21633
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AFAIK the Russian MLT-1, MLT-2 etc., equivalents of TR151 - 154 types, had tempco 200ppm and 500ppm.
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Old 24th March 2012, 09:31 AM   #21634
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Quote:
Originally Posted by Wavebourn View Post
Distortions, i.e. dependence of resistance on voltage and on power. Since the resistor is in feedback, their non-linearities shape non-linearities of the whole amp which amplification factor is close to ratio betwen feedback resistors plus 1. If say resistor changes it's resistance 1% that means already 1% of distortions.
You need to put this in perspective. Ed Simon's article in Linear Audio showed voltage dependent distortion of reasonable quality resistors to be tens of dB below the amplier linearity.
Unless you use pathological resistors and/or pathological values, the notion that feedback resistor non-linearity does anything audible to an amp output is a nice story, but not more.

jan
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Old 24th March 2012, 10:05 AM   #21635
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Quote:
Originally Posted by Wavebourn View Post
I still can buy C5-5 and PTMN resistors, they are quite expensive though. They are wirewound resistors, non-inductive. Mentioned by VladimirK VS (BC) resistors loved on Russian forums have huge inductance, actually.
Anatoliy, do not be so brutal.There is no any issue with BC resistors inductance. Wirewound resistors are good at definite positions, but even if non-inductive, they have clear issues with parasitic indactance and capacitance. With resistors, major issue is what materials and manufactiring technology were employed. You probably know, that for best old russian military parts, it was typical to find in parts such materials, as Rhodium, Platinum, Palladium, not mentioning Gold and Silver.
BC resistors of the years 1978 are non-magnetic, but the same of 1989 are already magnetic. C2-10 always where elite parts, BLP are very good sonically. MLT resistors never approached elite leage, they are just to dissipate heat on them.
Just from curiousity I have measured complex impedances of various resistors at few frequencies (impedance modulus R Ohms and the phase angle in degrees):
----------------- 100kHz 200kHz 500kHz 1000kHz
C2-10 0,5W 2103R 2100R 2086R 2035R
-0,01deg -0,02 +0,02 +0,05

BLP 0,1W 2915R 2911R 2892R 2829R
-0,01 -0,03 -0,04 -0,09

BC 0,25W 3381R 3377R 3357R 3286R
-0,03 -0,06 -0,09 -0,18

PTMN 0,5W 12107R 12280R 13290R 15720R
+1,08 +1,76 +2,50 -4,83

The PTMN resistors change their behaviour from rather essential inductive (the + sign of the phase angle) to big capacitive ( the - sign). There must be a resonant deep at definite frequency.
Non-wire resistors are useless to judge from measured parameters, they behave in sound schematics mainly depending on the materials they are made from.

Pavel, I am not sure that tempco parameter is the main for sound quality. It is similar to THD, it could be allowed to be higher, but sound details do not depend much on it.

Last edited by VladimirK; 24th March 2012 at 10:11 AM.
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Old 24th March 2012, 11:30 AM   #21636
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Similar measurements for C2-10 0,5W of higher resistance:
20kHz 50kHz 100kHz 200kHz 500kHz 1000kHz
8624R 8622R 8620R 8608R 8546R 8330R
-0,01deg -0,03 -0,03 -0,05 -0,07 -0,37

Impedance is always slightly capacitive, they are designed for UHF applications.
Measurementwise, the MLT resistors are not bad, but it does not correlate with their sound effects. Here are measurements for 10K 0,5W MLT resistor:
20kHz 50kHz 100kHz 200kHz 500kHz 1000kHz
9968R 9960R 9966R 9954R 9888R 9658R
0,00deg +0,03 -0,03 -0,05 -0,06 -0,33

Last edited by VladimirK; 24th March 2012 at 11:38 AM.
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Old 24th March 2012, 11:51 AM   #21637
SY is offline SY  United States
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Quote:
Originally Posted by janneman View Post
You need to put this in perspective. Ed Simon's article in Linear Audio showed voltage dependent distortion of reasonable quality resistors to be tens of dB below the amplier linearity.
Unless you use pathological resistors and/or pathological values, the notion that feedback resistor non-linearity does anything audible to an amp output is a nice story, but not more.
Did you ever see the old Audio article "The Sad Tale of a 1/2 Watt Resistor"? Probably from the early '50s.
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Old 24th March 2012, 12:07 PM   #21638
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Originally Posted by SY View Post
Did you ever see the old Audio article "The Sad Tale of a 1/2 Watt Resistor"? Probably from the early '50s.
No, never heard of it. You have a copy?
And Good Morning BTW

jan
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Old 24th March 2012, 12:15 PM   #21639
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Quote:
Originally Posted by kamis View Post
<snip>I know that they are 5% metal film types,but temperature co. value is not published.<snip>
MLT and OMLT, 1/4 to 2 W
-60 to +20 deg C = +/- 1200 ppm
+20 to +125 deg C:
+/- 600 ppm (up to 10K)
+/- 700 ppm (10K to 1M)
+/- 1000 ppm (above 1M)

As you can see, there's nothing special about their tempco.

Let's move on.

Best,

Last edited by elektroj; 24th March 2012 at 12:30 PM.
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Old 24th March 2012, 12:16 PM   #21640
SY is offline SY  United States
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Late night last night or I would have been up earlier. Went with Sonidos to see a GREAT show at Threadgill's.

Anyway, 12/57. If you have the Audio Anthology series, it's in Volume 4. The pathology was a bit higher than Ed's -140dB wonders. If the resistor is specified properly, VCR is much more important than tempco.
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