hmm! diy xperts and audio xperts come in!

[neutralzz 0]

in my amp..if i were to increase the resistance of my output.. any deterioration of sound?

 

apparently people who use a resistance plug had experienced sound improvements

 

and.. which op-amps are known to have very good dynamic control, and have tamer highs?

 

i want to modify digi01's earmax clone for an even better sound .. tubes make v good pre-amping, but one thing i feel is that the tubes are a little less controlled.. sound's a little looser with a bit of decay delay..

 

thus.. opamp circuitry before or after the tubes?

[huangyong 0]

IMHO, incresing output resistance will tone down the brightness, because grnerally the high frequency is small amplitude.

 

"pre"-amping means "before", so it gonna be before.

 

can try to add in a simple buffer after the tube amp. buffer such as BUF634 or even discrete buffer if you into hardcore DIY.

[neutralzz 0]

hmm! true true.. cuz if i put the opamp circuitry as pre, and tubes as power.. the sound will still be loose i guess.. :S

 

 

[adhoc 0]

IMHO, incresing output resistance will tone down the brightness, because grnerally the high frequency is small amplitude

any evidence to back this up, or is it just speculation?

 

afaik, putting a resistor in series before output simply fools the amp into thinking that it is driving a load with higher-impedance. this prevents instability in some amps, but will not solve, for example, a amp not being able to supply enough current.

 

in addition, adding a resistor in series before output would put additional thermal noise into the signal path (every resistor has a 'ppm' rating - the lower, the better) and brings up the possibility of (admittedly minor) channel imbalance due to differences in resistor value between the 2 resistors for L/R.

[kross 0]

i think the idea is that higher frequencies are usually produced relatively weaker than lower frequencies, especially for the higher harmonics of sound. for example it is harder to hear a loud flute as compared to a loud trumpet?? or a loud high C5 vs loud C2 on the panio?? so if the weaker higher frequencies still go through some attenuation by the resistors the higher frequencies might not be so audible after output. however, the resistor would dampen all signals regardless of frequency i think. just my idea..

[adhoc 0]

however, the resistor would dampen all signals regardless of frequency i think. just my idea..

frequency does not affect the proportion of attenuation.

 

in fact, the human ear is more sensitive to high(er) frequencies than lower ones, so...

[huangyong 0]

Edited October 18, 2005 by huangyong

[huangyong 0]

What i refer to is the higher frequency, somewhere near 20k. which cant really hear.. but can feel the brightness....

refer to the graph.. human are most suceptible to midrange...

 

kross, thank you for defending the theory, i m sure i read it somewhere... gonna check first..

[neutralzz 0]

i think the idea is that higher frequencies are usually produced relatively weaker than lower frequencies, especially for the higher harmonics of sound. for example it is harder to hear a loud flute as compared to a loud trumpet?? or a loud high C5 vs loud C2 on the panio?? so if the weaker higher frequencies still go through some attenuation by the resistors the higher frequencies might not be so audible after output. however, the resistor would dampen all signals regardless of frequency i think. just my idea..

hmm.. i believe any modification on the output changes the raw timbre of the frequency.. frequency may be the same, but the timbre varies.. my dad used to emphasize a bit on timbre .. in the aspect of audio representation etc..

 

a sound with a basic frequency but no timbre is like a smooth oscillator or a tuning for maybe.. a note of 440hz from a piano and a flute can be of the same amplitude and frequency, but ones smoother the other one is different..

 

 

[kross 0]

yup, human ear is actually more sensitive to the mid-highs, around octave above middle A range, from 1kHz to 3kHz, more than the highs.

 

each instruments has its own unique timbre which makes us able to distinguish one instrument from another. the interaction between the harmonics give rise to unique timbre and thus characteristic sound. regarding the notion that resistance alter the frequencies to different extent and thus changing the timbre, i'm not too sure about that. maybe the interaction between the background noise from the resistor and the original signal might afect the timbre..? but looking in terms of voltages variations, then the resistor would attenuate equally for all the signals, thus all frequencies..no?

 

just sharing what i know huangyong...

Edited October 18, 2005 by kross