Why not?
Just analyze the word.
"Pre" means "before"
Pre- | Definition of Pre- at Dictionary.com
"Amp" is the contraction of Amplifier ... which also has wide meaning.
In our craft it *usually* means "Power" Amplifier.
That said, the full word "Preamp" usually alludes to a device which has some gain, __controls volume__ , maybe has anput selector for various sound sources , filters, etc. , but not necessarily.
Personally I would use the description "External Volume Control", because it does *exactly* the same as a Volume Control pot mounted inside the power amplifier, but hey, that´s me.
Nice try. Now go to that exact same source and look up "preamplifier"
"an electronic device that amplifies a very weak signal, for example from a microphone or pickup, and transmits it to a main amplifier."
If it doesn't amplify, it cannot be a "pre-amplifier". If it only attenuates the amplitude of the signal, and further, in doing so, it reduces the total power of the signal, it cannot qualify as an amplifier, or preamplifier.
So, you would define a "preamp" to include something that doesn't amplify. The Dictionary once again disagrees: " "amplifier" - an electronic device for increasing the amplitude of electrical signals, used chiefly in sound reproduction."
If it doesn't increase, it can't be an amplifier.
Ok by me. My only point to make here is that the term "passive preamplifier" is a nonsense term as there can be no such thing.
Depends if the term means an amplifier before the main amplifier or
A a module that is before the main amplifier.
According to online dictionary it is:
preamplifier
[ pree-am-pluh-fahy-er ]SHOW IPA
noun
a device in the amplifier circuit of a radio or phonograph that increases the strength of a weak signal for detection and further amplification.
A a module that is before the main amplifier.
According to online dictionary it is:
preamplifier
[ pree-am-pluh-fahy-er ]SHOW IPA
noun
a device in the amplifier circuit of a radio or phonograph that increases the strength of a weak signal for detection and further amplification.
I think my question got lost in the above discussion, but what is the reasoning behind picking 10k (or even 5k, as was also suggested)? According to the DACT calculator, even using pots up to 250k with my 18k input amp shouldn't cause audible low-pass-filtering (although I'm not sure what my capacitance is; the cables are short at least). Considering the sticky says avoid using low impedance pots in order to avoid source damage, surely a pot of at least 50k would be safer?
You won't damage any normal 'source' output by dangling a low value pot on the end of it. 99% of outputs are short circuit proof anyway.
Mismatching impedances such as a 250k into 18k causes no problems due to high frequency attenuation because it is nothing to do with resistive values but rather capacitance that causes those problems. And that is an unknown value.
If your amp has an 18k input impedance then I would suggest either 10k or 20 (22)k as a good fit. Either is low enough in value to not cause problems with whatever capacitance is there (and there will be some small amount) and high enough not to excessively load the driving source component.
As mentioned, low loading won't harm anything but it can increase distortion as the stage works harder.
Mismatching impedances such as a 250k into 18k causes no problems due to high frequency attenuation because it is nothing to do with resistive values but rather capacitance that causes those problems. And that is an unknown value.
If your amp has an 18k input impedance then I would suggest either 10k or 20 (22)k as a good fit. Either is low enough in value to not cause problems with whatever capacitance is there (and there will be some small amount) and high enough not to excessively load the driving source component.
As mentioned, low loading won't harm anything but it can increase distortion as the stage works harder.
Just to update, I picked up a Tisbury Passive, which to my ears with the Naim power amp, sounds as good as, if not better than, my Naim integrated that cost 3x more. So the 10k pot (well, stepped resistors) seems to be working well, with no significant filtering of frequencies. Thanks for the input. Matt
I was under the impression that a log pot was just 2 different rates in the pot approximating a log taper. If that
is true, wouldn't the 10:1 loaded linear pot more closely approximate a true log pot? I get around it by using a
PGA2311 which comes closer to log than any physical pot and has nearly perfect channel tracking. No pot a
normal person can afford can do that.
G²
Depends on the pot, cheap ones are just two tapers. Better ones 3 or 4. Good ones true log.
The the taper has another logarithmic relationship. Accuracy:cost. Apparently there are pots by CTS that come "close enough" to log and are not obviously segmented, and around $5. Projects I did several decades ago used real log pots and RZ tapers (that was reverse-log) by Bournes, but I can no longer find those parts, might be discontinued, might be renamed. We used to use Alps also, IIR the RK217 series not only follows a real log taper but stereo pots track well, which frankly is more important anyway. They're in the $15/ea category.
Then there's the P&G stuff, and those are for the extra-mortal.
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