Resistor test TX7525 AMRG CMF55 - diyAudio
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Old 2nd June 2011, 08:38 AM   #1
Scheff is offline Scheff  Germany
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Join Date: Feb 2009
Smile Resistor test TX7525 AMRG CMF55

Hi, my first tribute to the forum and anybody who wants to know. (I hope more than one.)

After a long period of preperation I got three kinds of resistors to listened to.
I tried them in a Fender Schulte-Reverb (Pro Reverb with Schulte tuning, n o t for sale) because I feel that a musical instrument like a guitar is a very fine and sensitive signal for hearing differences in colour and dynamics. It will definitely sound different in a hifi preamp or wherever, but the tendencies in the differences of sound will remain the same. I tried them at three different cathondes between input stage and the tube just before the power tubes (do you say phase inverter? (english was never ma favourite subject)

So here are the candidats.

1.) CMF55 dale non magnetic.
2.) Texas components TX2575 Z-2575 foil
3.) Carbon AMRG from Amtrans, Japan.

They all were good resistors and itīs always a matter of personal taste. I donīt believ in objectivity, becaus even the cable of the microphone used for the saxophonrecord ha an own sound. Thereīs no objective material on this planet. So the only thing you can do is to listen and like it or not.

1) CMF55 has a warm and relative open sound, a musical sound over all but in the high end it could be a little more open. If your in all sound is a little too brilliant, this could be your choice. In all, a warm , musical sounding resistor.

2.) This one sounds really open. Big bass sound, the strings of my stratocaster seemed to come out more out of the speakers, very good seperation of the single string, rich in detail, remided to a piece of wire.
They have the tendency not to make sound. On the other hand, they are the most technically sounding resistors. At some cathodes I liked these most, but not at all places. As always a matter of taste.

3.)These black beauties sounded very open, airy with a little sweet touch, in a musical sense wonderfull, but a little sound making. Big bass too. At some places I loved these most, but not everywhere.

So I cannot take you decisio away, I just can giv a very little hint to the different tendencies. You always have to listen by yourself.

And donīt forget to try the orientation of the resistors. It doesnīt sound the same!!! If you change the connectors, the sound changes too. Not too much, but to much to be ignored.
As I tried them only in the cathod of tubes, I cannot really say much about hiss now.

AMRG can be bought in japan (homeage of manufactorer Amtrans), Texas Compnents can be bought on their homepageg, and I think itīs Schuro in Germany where you can get CMF55.

Each of these is worth a try. And compared to many standard resistors specially the AMRG and the TX are champions League

If you find mistakes in my english, in my words or thoughts, feel free to keep them.

So have fun Scheff
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Old 16th August 2011, 09:38 AM   #2
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which one do you recommend between vishay CMF series and SMA0204 series for hi end audio application?
from what view?
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Old 16th August 2011, 10:07 AM   #3
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Join Date: Feb 2004
Location: South Wales
What part of the circuit was the resistor changed?

How many were changed?

All in the amp--or just one or two? Was exactly the SAME value used as the original, and was the original still in spec? Were all the 'candidates' the same values as those changed?

IME resistor Make and Type play little in the sound Quality, providing a Low-Noise type is used, ie--NOT solid Carbon compo, which can hiss like hell, and are probably the worlds worst resistors if used in the wrong places!

Much more depends on the Tube Op-Point and the actual Topology, as well as the quality of the O/P Transformer, and NOT resistors .....

Please, Define--'Open' and 'Warm' and 'Musical Sounding Resistor'

Sounds like marketing twaddle for audiofools to me!
Das Beste Oder Nichts
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Old 30th April 2012, 09:38 PM   #4
Scheff is offline Scheff  Germany
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Join Date: Feb 2009
On my ears, the sound of resistors is as important as the tube op point, becaus I tried that , too and in Fender Guitar amps the difference of the sound of resistors is amazing and hearabele just like caps. I also tried the TX2575 as Voltage divider in a LT1084 Voltage regulator and itīs the same, you can hear the difference. If not, you donīt need hifi. Also pay a lot attention on the direction of the resistors! One direction sounds dark, the other one sounds brighter, itīs up to your ears, what you like best, and at this place, I like the TX2575, too.
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Old 1st May 2012, 11:56 AM   #5
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Join Date: Aug 2005
Originally Posted by Scheff View Post
Also pay a lot attention on the direction of the resistors! One direction sounds dark, the other one sounds brighter, [...]
That's a quite catastrophic finding for the high-end society!

Most of the resistors in my circuits are carrying AC currents, i.e. the direction changes with every half-wave. Your scientifically proven result explains why my soundstage is so unstable, I guess it just changes too fast (20 to 20,000 times per second) between dark and bright for me to distinguish

I think I need a beer. Now.

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Old 1st May 2012, 12:00 PM   #6
Scheff is offline Scheff  Germany
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oops, I forgot to mention, that the LT 1084 (or 1085???) was in the heater power supply for the tubes.
But I donīt think that this is bad, it takes more time, but itīanother chance to desing sound.
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Old 4th May 2012, 11:58 PM   #7
gabor is offline gabor  Hungary
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Hi All,
Just my 2 (3) Cents. Everyone will believe - resistors have their character. All have a character. A bit less people will think that resistors can sound differently in one or opposit direction - but I can assure You all, Scheff is right, they do sound different in different direction. I made quite a lot of comparisons and listened to differences of one component change ( don't change more components in one step - you will go mad). For sure, you can hear resistors turning. But, not first. You should try it some times to catch the effect. Once you get it, and know what to listen to - it is relative easy. The better the resistor - the easier to hear the direction.
If you do not hear any difference, your audio system has less resolution than enough to hear this are not enough experienced listener to hear this.
I kid you not, hearing is a complex physiological AND brain derived phenomenon. The best thing is - You can learn to hear. Your brain learn to differentiate very tiny acoustic information, by time.
OK, back to resistors.
Resistors have low effect on musicality. They effect on distortions. In fact, two kinds of distortions. Harmonic and spectral distortions.
Just imagine, in every audio chain we have a less than ideal spectrum.
Every components have their spectral behaviour. Most DIY-ers change the coupling caps, resistors, wires, etc. but use inferior quality connectors, resonant amplifier boxes, ad hoc power transformers. In the end of the chain, we get the superponed spectrum of ALL components. The silky smooth sound of expensive caps with resonances and magnetic effect from the simple amp box. Great engineering.
If we consider sound improvements pro Euro, first get good cables for resolution and spectrum balance, the best psu you can afford for musicality, then good caps for both of aboves , nice sounding tubes for low colouration and then you can change the resistors for lowering the distortions. And all of them should be in balance with the others. Sadly, one set of resistors with one set of cables can sound better than an other set, but easily you can get different opinion once you change only one 10 cm long wire in your amp...
In the last 30 years since I build amplifiers I found that resistor issue is of lesser importance, IF you get a decent quality set of resistors. Dale is a really good start. Even Draloric is acceptable, nice sound if not quite the best resolution. Caddock is way too overpriced, Tantalum is thin sounding but smooth, low distortion. Carbons can soften and some dull the sound, PRP is like a loudness button. Mills are OK, slight brightness here but just a touch.
It is always a good practice to make every values you need from 2 or 3 resistors in parallel. This reduces the distortion, and adds energy to the sound.
Don't forget, you can tune your amp soundwise with the feedback resistors. Serial ones add the opposit of their own sound (i.e. a lean sounding res in series feedback adds weight to the amp) and the parallel one adds it's own character. If you want the right balance, make sure you use the same type of resistor in both parts of the feedback.
TCO also an important factor. Keep TCO LOW!!! It is hard to imagine how much distortion derived from bad TCO resistors.
Once again: spend majority of your money on power supply, cabling and caps, and THEN the resistors. When you get really satisfying sound, get good connectors and damping sheets to make the enclosure unresonant. A surprising effect that is mostly overlooked.
Scheff, from this point of view, in an ideal amp and in an ideal system I would be the first people to begin turning the resistors left or right. But in real life, this effect is very tiny for most people, less recognizeable than the set of 1/4 bottle (green, Unicum spheric bottle, labels off!) of vegetable oil in every corner of your room. may think I am crazy. I was such sceptic, too. But when I heard this effect I was blown away. Now, I have the 4 bottles in the corners. 3 days needed to have them "settle down" , I don't know how it works but they do something with the energies in the room. Take them out and your soundstage crashes down. Take them back -4 corners - soundstage back. A far more drastic effect than any resistor directioning. TRY IT.
4 bottles Unicum or Next - drink it COLD. It enhances the effect.... OK, this last one is a joke...
Cheers, Gabor (Budapest)
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