Pitfalls of paralleling different resistor brands?

phrarod · 5th March 2011, 01:24 AM

So here's my story. I have naked resistors for cathode bias. Lowest noise, incredibly clear, but can tend to the lean side. My favorites for tone are Roederstein. But those alone don't have the transparency I'm after. So for a while I paralleled them calculating the resistance of the Roederstein so it wouldn't change the overall resistance.

I just finished the project and decided to listen with just the naked resistors. Clearer, cleaner, more transparent. Moved to the leaner side.

So my question is: am I just injecting noise by paralleling these trying for the best of both worlds? I've tried just about every resistor in this position. Since I have an incredibly simple circuit the tube bias is the only place I have R/C in the signal path so the R or the C make a huge shift in the sound.

RTF671 · 5th March 2011, 01:31 AM

By paralleling them you can only inject max of half the noise because a split is a current divider (if the resistances are equal). I have heard of people doing that before to add some tone in their signal path.

What kind of amp and how many positions are you thinking of doing it to?

phrarod · 5th March 2011, 01:38 AM

They are not equal values. The Naked is 221R and the Roederstein is 91K = 220.46R

This is a pre-amp. Just in the cathode bias.

RTF671 · 5th March 2011, 01:46 AM

Give it a whirl? See how it goes, thats the best way to find out.

phrarod · 5th March 2011, 01:47 AM

You need to read the post again. I have been running that way. I just pulled it today. Pluses and minuses.

Ty_Bower · 5th March 2011, 02:27 AM

By blending multiple types of resistors, you will get a blend of all their best attributes. You will also get a blend of all their worst attributes. That means you will end up with some of the leanness and lack of tone you dislike from the Nakeds, and some of the noise and loss of transparency you've heard in the Roederstein. As you say, pluses and minuses. The choice is up to you.

RTF671 · 5th March 2011, 03:22 AM

I'm sorry, I missed that part. But yes each one will color the amount of current running through it.

On the upside, if the only thing you have to worry about is brands and flavors of your resistors your amp must sound great

DF96 · 5th March 2011, 10:26 AM

Having 221R in parallel with 91K means that the 91K only contributes 0.24% of whatever happens i.e. it can only have virtually no effect. It could be very noisy or very non-linear and you probably would not notice. If it was a perfect resistor then it would have almost no effect in 'correcting' the 221R. Maybe I have missed something, but such a combination seems totally pointless.

phrarod · 5th March 2011, 03:40 PM

DF96 -- This is the part of theory that meets audio reality. Many things make no sense yet have sonic effects. The 91K definitely adds some body and loses some transparency. The explanations is what I was after. The fact its only contributing .24% makes it not so parasitic in my understanding.

RTF -- thanks also, the preamp does sound amazing to me and I've had many classic and expensive ones (which price doesn't result in quality) come through here by way of others and I've owned some good ones.

Much appreciated to everyone.

Rundmaus · 5th March 2011, 03:42 PM

If it can't be measured or theoretically explained, it is a part of audio fantasy, not audio reality. Better to keep these two apart.

Greetings,
Andreas

5th March 2011, 01:24 AM	#1
phrarod diyAudio Member Join Date: Aug 2005	Pitfalls of paralleling different resistor brands? So here's my story. I have naked resistors for cathode bias. Lowest noise, incredibly clear, but can tend to the lean side. My favorites for tone are Roederstein. But those alone don't have the transparency I'm after. So for a while I paralleled them calculating the resistance of the Roederstein so it wouldn't change the overall resistance. I just finished the project and decided to listen with just the naked resistors. Clearer, cleaner, more transparent. Moved to the leaner side. So my question is: am I just injecting noise by paralleling these trying for the best of both worlds? I've tried just about every resistor in this position. Since I have an incredibly simple circuit the tube bias is the only place I have R/C in the signal path so the R or the C make a huge shift in the sound.

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5th March 2011, 01:31 AM	#2
RTF671 diyAudio Member Join Date: May 2008	By paralleling them you can only inject max of half the noise because a split is a current divider (if the resistances are equal). I have heard of people doing that before to add some tone in their signal path. What kind of amp and how many positions are you thinking of doing it to?

5th March 2011, 01:38 AM	#3
phrarod diyAudio Member Join Date: Aug 2005	They are not equal values. The Naked is 221R and the Roederstein is 91K = 220.46R This is a pre-amp. Just in the cathode bias.

5th March 2011, 01:46 AM	#4
RTF671 diyAudio Member Join Date: May 2008	Give it a whirl? See how it goes, thats the best way to find out.

5th March 2011, 01:47 AM	#5
phrarod diyAudio Member Join Date: Aug 2005	You need to read the post again. I have been running that way. I just pulled it today. Pluses and minuses.

5th March 2011, 02:27 AM	#6
Ty_Bower diyAudio Member Join Date: Mar 2007 Location: Newark, DE	By blending multiple types of resistors, you will get a blend of all their best attributes. You will also get a blend of all their worst attributes. That means you will end up with some of the leanness and lack of tone you dislike from the Nakeds, and some of the noise and loss of transparency you've heard in the Roederstein. As you say, pluses and minuses. The choice is up to you.

5th March 2011, 03:22 AM	#7
RTF671 diyAudio Member Join Date: May 2008	I'm sorry, I missed that part. But yes each one will color the amount of current running through it. On the upside, if the only thing you have to worry about is brands and flavors of your resistors your amp must sound great

5th March 2011, 10:26 AM	#8
DF96 diyAudio Member Join Date: May 2007	Having 221R in parallel with 91K means that the 91K only contributes 0.24% of whatever happens i.e. it can only have virtually no effect. It could be very noisy or very non-linear and you probably would not notice. If it was a perfect resistor then it would have almost no effect in 'correcting' the 221R. Maybe I have missed something, but such a combination seems totally pointless.

5th March 2011, 03:40 PM	#9
phrarod diyAudio Member Join Date: Aug 2005	DF96 -- This is the part of theory that meets audio reality. Many things make no sense yet have sonic effects. The 91K definitely adds some body and loses some transparency. The explanations is what I was after. The fact its only contributing .24% makes it not so parasitic in my understanding. RTF -- thanks also, the preamp does sound amazing to me and I've had many classic and expensive ones (which price doesn't result in quality) come through here by way of others and I've owned some good ones. Much appreciated to everyone.

5th March 2011, 03:42 PM	#10
Rundmaus diyAudio Member Join Date: Aug 2005	If it can't be measured or theoretically explained, it is a part of audio fantasy, not audio reality. Better to keep these two apart. Greetings, Andreas