What's the difference between parts in amp

paavi · 19th July 2010, 01:02 PM

So i've been wondering what's the difference between 0.1% metal film resistor and some less quality 1% resistors in amp. I tried to look here but i didnt find clear answer. So should i put in my diy amp (tda7294) expensive resistors with low tolerance, or some normal cheap 1% metal/carbon resistor? And same thing with caps, is something like panasonic fc good enough or should i put something with higher quality? and now i mean in signal path?.
Is there so much difference in sound?
btw sry for bad english

jacco vermeulen · 19th July 2010, 01:52 PM

How many power amps with 0.1% accurate resistors have you seen so far ?

paavi · 19th July 2010, 02:32 PM

None, but im asking becouse it seems that everyone in this forum is saying that you must have them.

jacco vermeulen · 10:45 AM

Most amps have feedback to correct output errors, makes it pointless to use high precision resistors.

Least exotic use of 0.1% resistors is in a stepped ladder attenuator, and very very few commercial preamps have a volume attenuator that accurate.
0.1% accurate resistors cost a multitude of 1% types, depending on the quality between 4 to +100 times as much.
Selecting them yourself takes a special set-up or a DMM that costs several $k.

paavi · 20th July 2010, 02:01 PM

Okey. And now to my second question, are capasitors on same line? must there be some high quality caps with low tolerance in amp or are normal elkos good enough?

jacco vermeulen · 20th July 2010, 05:37 PM

Sort of like asking if it matters which tires to put on a car.

A lot favor common industrial quality electrolytics, nothing fancy but affordable.
Those folks usually stay on blazed trails in the audio woods ; moderate bandwidth, very moderate slewrate and risetime designs.
For higher demands on electrolytic caps, one might think it matters for designs with bandwidths of several 100kHz, slew rates figures on the upper side of 100V/uS, rise times far below 1us, and peak current capability of +100A.

Then there's the IC amp enthousiast, known for experimenting with the most exotic parts on the backbone of a $5 IC.
Spec wise, IC amps are by the book, but not spectacular in any area, imo.
The chip amp afficinados are generally not highly skilled in design theory (and practice), but mainly judge by the sounds.
Never worked for me, i find it hard to choose which of the voices inside my head is telling the truth and too often picked the wrong team.

mickeymoose · 21st July 2010, 01:29 PM

0.1 and 1% Rs are found extensively in bridge/parallel amp setups. Have a look at the app. note AN1192 for the National LM3886
E

jacco vermeulen · 02:33 PM

Duuh, it's not the 0.1% value accuracy but the matching precision that's important for parallel amps.

WithTarragon · 21st July 2010, 02:37 PM

Quote:

Originally Posted by jacco vermeulen

Duuh, it's not the 0.1% value accuracy but the matching precision that's important for parallel amps.

Is it really necessary to phrase your respsonse in such a condescending tone?

When starting out on a new hobby or passion, we have all had to ask questions and to learn. I suspect that at one time you were also new to this.

jacco vermeulen · 21st July 2010, 02:42 PM

Tom,
"duuh" is just a web expression, not meant as condescending in any way.

19th July 2010, 01:02 PM	#1
paavi diyAudio Member Join Date: May 2010	What's the difference between parts in amp So i've been wondering what's the difference between 0.1% metal film resistor and some less quality 1% resistors in amp. I tried to look here but i didnt find clear answer. So should i put in my diy amp (tda7294) expensive resistors with low tolerance, or some normal cheap 1% metal/carbon resistor? And same thing with caps, is something like panasonic fc good enough or should i put something with higher quality? and now i mean in signal path?. Is there so much difference in sound? btw sry for bad english

20th July 2010, 10:41 AM	#4
jacco vermeulen diyAudio Member Join Date: Oct 2004 Location: At the sea front, just under Rotterdam	Most amps have feedback to correct output errors, makes it pointless to use high precision resistors. Least exotic use of 0.1% resistors is in a stepped ladder attenuator, and very very few commercial preamps have a volume attenuator that accurate. 0.1% accurate resistors cost a multitude of 1% types, depending on the quality between 4 to +100 times as much. Selecting them yourself takes a special set-up or a DMM that costs several $k. Last edited by jacco vermeulen; 20th July 2010 at 10:45 AM.

21st July 2010, 02:31 PM	#8
jacco vermeulen diyAudio Member Join Date: Oct 2004 Location: At the sea front, just under Rotterdam	Duuh, it's not the 0.1% value accuracy but the matching precision that's important for parallel amps. Last edited by jacco vermeulen; 21st July 2010 at 02:33 PM.

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19th July 2010, 01:52 PM	#2
jacco vermeulen diyAudio Member Join Date: Oct 2004 Location: At the sea front, just under Rotterdam	How many power amps with 0.1% accurate resistors have you seen so far ?

19th July 2010, 02:32 PM	#3
paavi diyAudio Member Join Date: May 2010	None, but im asking becouse it seems that everyone in this forum is saying that you must have them.

20th July 2010, 02:01 PM	#5
paavi diyAudio Member Join Date: May 2010	Okey. And now to my second question, are capasitors on same line? must there be some high quality caps with low tolerance in amp or are normal elkos good enough?

20th July 2010, 05:37 PM	#6
jacco vermeulen diyAudio Member Join Date: Oct 2004 Location: At the sea front, just under Rotterdam	Sort of like asking if it matters which tires to put on a car. A lot favor common industrial quality electrolytics, nothing fancy but affordable. Those folks usually stay on blazed trails in the audio woods ; moderate bandwidth, very moderate slewrate and risetime designs. For higher demands on electrolytic caps, one might think it matters for designs with bandwidths of several 100kHz, slew rates figures on the upper side of 100V/uS, rise times far below 1us, and peak current capability of +100A. Then there's the IC amp enthousiast, known for experimenting with the most exotic parts on the backbone of a $5 IC. Spec wise, IC amps are by the book, but not spectacular in any area, imo. The chip amp afficinados are generally not highly skilled in design theory (and practice), but mainly judge by the sounds. Never worked for me, i find it hard to choose which of the voices inside my head is telling the truth and too often picked the wrong team.

21st July 2010, 01:29 PM	#7
mickeymoose diyAudio Member Join Date: Nov 2008	0.1 and 1% Rs are found extensively in bridge/parallel amp setups. Have a look at the app. note AN1192 for the National LM3886 E

21st July 2010, 02:42 PM	#10
jacco vermeulen diyAudio Member Join Date: Oct 2004 Location: At the sea front, just under Rotterdam	Tom, "duuh" is just a web expression, not meant as condescending in any way.

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