[danlaix]

Hello guys, just wanna know if there is any difference
in using the normal blue 0.25W Metal Film resistors
and the black 0.25W Precision Metal Film resistors for
building the Meta42?
Any differences in the sounding output?
Which type of resistor is preferred?
(althought the favourite and norm seems to be the blue metal film)

Thanks.

 

[danlaix]

oh, common. Nobody wants to share anything here?
Is my question wrong or that stupid??

 

[jasonhanjk]

Hello Dainlax!!!

If you have the money for the precision resistor, I say go for it. The overall result would be a slightly better gain control between left and right channel. Meaning the gains for the 2 channel are equal.

 

[peranders]

You could also you plain 0.6 W metal film (same size as carbon 0.25W).

If you are worried about precision, my types, Vishay, has 0.3% average error. Not many applications need more precision if we only talk about the value.

 

[Tomo]

Hi,

I don't think it would make much of difference. Only difference between Metal Film and Precision Metal Film is the tolerance.

Right now, our manufacturing technology is so advanced that it is possible to created identical duplicates with failure rate of something like one thousand to one. If I take a set of RN55 (1%) from a same roll, I get something like ~0.5% tolerance. I match that and I get something even lower.

However, this will not change the sound quality since the material is the same. (Unless of course your current resistors are crap.) Try using some other materials. Carbons, Metal Oxide, Wirewound, substrate / plate, chip, etc.

Tomo

 

[Arzela]

The precision resistors usually have much
better temperature coefficients (15-50 ppm verses 100-250)

 

[peranders]

Temp coeff is better but how much will this make in dB? 1% = 0.08730 dB 0.3% = 0,050458 dB.

200 ppm and 30 deg temp change = 0.006 = 0,052 dB

Seriously, I have a hard time to hear less than 1 dB. Low ppm resistors aren't necessary if the only have influence on gain but maybe if it concerns DC balance and of cource if you really like "technical" performance (like I do).

 

[Tomo]

Hey,

Temperature coefficient is much of problem for us. Our amp temperature hardly changes. Besides it is waaaaay too good for our standard operating temperature.

Besides, it wouldn't effect sound anyway. Given certain temperature, the resistor values do not change over time.

You are paying attention to a wrong thing here. We worry about that when we build something like Apache helicoptors or Tomahawk missiles where temperature variation is so freaking large not to mention the necessity of operation in varying climate.

Try some other resistors. Resistor-rolling can be good given you do that with care. (because some resistors have pecuriorities which can mean a load of difference)

T

 

[peranders]

Quote:

Originally posted by Tomo Hey, Temperature coefficient is much of problem for us. Our amp temperature hardly changes. Besides it is waaaaay too good for our standard operating temperature.

Tomo, did you forget a "not" somewhere? Why is temp co big problem in constant temp?

 

[Tomo]

Oops,

That is correct. I missed "NOT"

Quote:

Temperature coefficient is NOT much of problem for us. Our amp temperature hardly changes. Besides it is waaaaay too good for our standard operating temperature.

But seriously, I did some measurements myself on RN55 before. And the temperature variation between 77 Kelvin to ~400 Kelvin was about ... "teens."

For a record, I am not working on weapon engineering. I hear a lot about it though. ie. Some dude built a "unintentionally-temperature-dependent" missile guidance system. Transistors went bad due to heat and came back to the launch site ... Oooo joy.

Tomo