Carbon Composite Mojo?
- Silent Fly
- Resistor Ronker
I noticed that in the Xotic RC Booster schematics there is a 470R Carbon Composite on series with the output. I am intrigued by why a small resistor in that place is carbon composite and I would like to ask your opinion about it.
I understand the psychological (aka mojo) factor but just for the sake of it I calculated the contribution of this resistor to the signal.
Considering the output impedance of the emitter follower close to zero, a relatively heavy load of 100k, the resistor create of a voltage divider that attenuates the signal by 0.099 (-0.08dB).
If the resistor is non-linear by 50% (235R-705R) the attenuation would vary between -0.12dB and -0.16dB.
I may have made some mistake in my calculation but if I am right, the difference between carbon composite and metal film should be inaudible – or not?
I understand the psychological (aka mojo) factor but just for the sake of it I calculated the contribution of this resistor to the signal.
Considering the output impedance of the emitter follower close to zero, a relatively heavy load of 100k, the resistor create of a voltage divider that attenuates the signal by 0.099 (-0.08dB).
If the resistor is non-linear by 50% (235R-705R) the attenuation would vary between -0.12dB and -0.16dB.
I may have made some mistake in my calculation but if I am right, the difference between carbon composite and metal film should be inaudible – or not?
"Remember - all I am offering is the truth, nothing more". Morpheus
- Silent Fly
- Resistor Ronker
SorrySilent Fly wrote:...the attenuation would vary between -0.12dB and -0.16dB.
with R = 235ohm => -0.04dB
with R = 470ohm => -0.08dB
with R = 705ohm => -0.12dB
"Remember - all I am offering is the truth, nothing more". Morpheus
- soulsonic
- Old Solderhand
Information
I would say it's there for good luck mojo, but since it's hidden under goop the psychological theory doesn't hold up. Really, the only reason I can see to use a single carbon comp in a circuit full of metal film would totally be for psychological effect, which means it would need to be shown off.
I personally love mojo parts, but there's no point in using them if you're going to hide them!
Sure, sure... there can be very specific circumstances where a carbon comp would be preferred to a metal film... like a pulse-handling circuit where the minute inductance of a metal film would affect the wave in a negative way. But that is certainly not the case here!
I personally love mojo parts, but there's no point in using them if you're going to hide them!
Sure, sure... there can be very specific circumstances where a carbon comp would be preferred to a metal film... like a pulse-handling circuit where the minute inductance of a metal film would affect the wave in a negative way. But that is certainly not the case here!
"Analog electronics in music is dead. Analog effects pedal design is a dead art." - Fran
There's a simple formula for caps ans resistors in audio stuff: different material = different sound
No mojo, just a matter of personal taste.
Often you find CCs in military and industrial stuff. Due to vibrations the boards are stressed a lot and CCs are not as fragile as other Rs and won't fail under such conditions.
JHS
No mojo, just a matter of personal taste.
Often you find CCs in military and industrial stuff. Due to vibrations the boards are stressed a lot and CCs are not as fragile as other Rs and won't fail under such conditions.
JHS
- Silent Fly
- Resistor Ronker
True... but can you hear a difference between 0.12dB and -0.16dBJHS wrote:There's a simple formula for caps ans resistors in audio stuff: different material = different sound
No mojo, just a matter of personal taste.
[...]
"Remember - all I am offering is the truth, nothing more". Morpheus
True... but can you hear a difference between 0.12dB and -0.16dB [/quote]
You can hear a difference in sound if a LP guitar is wired old or new style. In theory there should be no difference, you can't measure different values, but you can hear that tone nuances and timbre are different.
A piano will be always tuned by ear and not with a strobe tuner or similar things and if you ask those guys they will tell you that their ears are the best eqipment and that no high tech stuff will do the job as good.
In terms of tone nuances the last judge should be your ears (of cause only if you not a deaf metalhead).
JHS
You can hear a difference in sound if a LP guitar is wired old or new style. In theory there should be no difference, you can't measure different values, but you can hear that tone nuances and timbre are different.
A piano will be always tuned by ear and not with a strobe tuner or similar things and if you ask those guys they will tell you that their ears are the best eqipment and that no high tech stuff will do the job as good.
In terms of tone nuances the last judge should be your ears (of cause only if you not a deaf metalhead).
JHS
- lolbou
- Old Solderhand
That's because a piano is never in perfect tune. Remember the well-tempered stuff and so on?JHS wrote:A piano will be always tuned by ear and not with a strobe tuner or similar things and if you ask those guys they will tell you that their ears are the best eqipment and that no high tech stuff will do the job as good.
A piano can't be exact on its whole range because of its inharmonicness (?), due to the different nature of its strings (plain or wound)...
Therefore, a strobo tuner will give you the good pitch for each note, but your piano will sound awful... There comes the ear
- Are you a mod or a rocker?
- Uh, no, I'm a mocker.
- Uh, no, I'm a mocker.
- Scruffie
- Opamp Operator
Hence why, (well in my experience and knowledge) alot of piano tuners are actually blind as it heightens there hearing, where as i would say maybe i should find a piano tuner to do my intonation after my last comment i can't help but feel a bit bad then.
Scruff.
Scruff.
- B_of_H
- Breadboard Brother
the only difference i've noticed in using them is that I have to check their true values because all of the ones I get are 5% tolerance or so they say. I'm terrible at math but when a 100k resistor can be 91k or 104k isn't that more than 5%.