IMO, no best, no worst.
It is a matter of preference.
Logic and technical analysis is good but not enough.
Thus it is good if someone has experienced most of the variants of volume control into his(her) audio system.
George
George - This was at 1kHz. I should go back and re-measure at 100Hz. The 150H number was pulled from the intact audio website. The old FAQ there used to make mention of "better sound" with less inductance. But, experimentation has always been suggested to get the most out of these for your own situation. Fortunately, restacking the lams is easy on those.
egellings - My Slagle attenuator is ready but I haven't had a chance to use it yet. My monoblocks are getting some minor changes at the moment so things are in disarray. The impression I got is simply more music coming through than before. Not just a peaky high end. Feels like you are hearing the upstream components / source with a veil removed. And output Z is dramatically lower with an AVC versus what you get with a resistive control.
egellings - My Slagle attenuator is ready but I haven't had a chance to use it yet. My monoblocks are getting some minor changes at the moment so things are in disarray. The impression I got is simply more music coming through than before. Not just a peaky high end. Feels like you are hearing the upstream components / source with a veil removed. And output Z is dramatically lower with an AVC versus what you get with a resistive control.
The transformer approach, although it works well, is unnecessarily complex for a function as straightforward as volume control for line level applications. The xfmr has more distortion producing mechanisms than a resistor has. Bottom line is, choose whatever you're a fan of.
Not sure if this one has been posted yet: See $300 for the pair at the bottom of https://intactaudio.com/atten.html
Wire it up like this: https://www.bartola.co.uk/valves/2015/04/06/avc-finished/
Wire it up like this: https://www.bartola.co.uk/valves/2015/04/06/avc-finished/
Than you William.
When the emotional dust settlles down on whatever stacking arrangement you decide to stick to, if you have a soundcard and REW, please take some step level and step freq distortion measurements (or a single multitone FFT) across the full coil and post them here.
George
Hi all,
I just completed a listening evaluation of George's latest creation with 3k5 turns on 49% Ni core and I'm happy to report that it sounds right spot on! The most neutral AVC so far. Moving from 7k turns removed that bass boost while revealed the finest high frequency content. Excellent with human voice! And no sign of ringing or saturation. A very nice equilibrium between permeability, inductance and perhaps stray capacitance? Although it seems a reasonable conclusion, it didn't work with the 80% core or even worse with steel.
Having heard all these iterations so far, I was actually surprised to hear an AVC that doesn't add its character to the music. At least under the conditions I've been listening. Seal of approval on this one!
I just completed a listening evaluation of George's latest creation with 3k5 turns on 49% Ni core and I'm happy to report that it sounds right spot on! The most neutral AVC so far. Moving from 7k turns removed that bass boost while revealed the finest high frequency content. Excellent with human voice! And no sign of ringing or saturation. A very nice equilibrium between permeability, inductance and perhaps stray capacitance? Although it seems a reasonable conclusion, it didn't work with the 80% core or even worse with steel.
Having heard all these iterations so far, I was actually surprised to hear an AVC that doesn't add its character to the music. At least under the conditions I've been listening. Seal of approval on this one!
Has someone have experience with an AVC wired for gain?
This is from Intact Audio:
Q - Can the units be wired for gain?
A - Yes, some people report good results but be aware that wiring for 6dB of gain means that the source will see only 1/4 the inductance of the full winding. Stacking the core with more interleave will recover the lost inductance, though the ultimate success may depend on your system and your requirements. It is also important to note the behavior of the device when used for gain might not make measurement conscious people very happy. We encourage experimentation and appreciate any and all feedback.
This is from Intact Audio:
Q - Can the units be wired for gain?
A - Yes, some people report good results but be aware that wiring for 6dB of gain means that the source will see only 1/4 the inductance of the full winding. Stacking the core with more interleave will recover the lost inductance, though the ultimate success may depend on your system and your requirements. It is also important to note the behavior of the device when used for gain might not make measurement conscious people very happy. We encourage experimentation and appreciate any and all feedback.
Thank you Kostas for spending energy and time to do critical listening again, especially with such a high ambient temerature
I will do the usual tests on those AVCs later on.
But as you and alexopth1512 have a balanced audio system, I will do some trials for a balanced AVC.
Hopefully a single AVC per channel (between + and - signal) will do the work.
I 'll report back
@swak I haven't tested the AVC wired for gain.
George
Some thoughts on the resistive Vs autoformer volume control dilemma. Actually, for a long time, none of them would find a place in my system. I've been using the digital volume control by decision and built the gain structure of the system around that. The old arguments about noise do not hold much with modern 32 bit microcontrollers, however it is still advised not to attenuate bellow -20dB. To keep up with that, a fixed voltage divider has to be inserted somewhere in the chain and no matter how straightforward this might seems, there was evidence that it affects the tonality of the gain stage. Experience with Salas DCG3 confirmed that and put me to thoughts about switching to analog volume control with all the parameters needed to be calculated consequently.
A resistive stepped attenuator being the most reasonable choice for me, probabilities to go for an AVC were very thin before this thread came up. Now I feel just a bit wiser... An AVC can have an immeasurable but strong signature just like resistive VC. Also, it can be neutral and transparent. So, what would be the reason to chose it over the other types? Well, the most impressive feature of the AVC in my opinion is its natural ability to match impedance. Just connect I/O and you are ready to go, no calculations involved. George confirmed that it works in balanced mode simply connecting it between hot and cold without any in series resistors to form the so called "U" or "H" shape attenuators. Do that with an ordinary potentiometer... Adding or not its character, it definately retains the sound of the gear it is connected to. I thing this is pricelles!
Ending with the usual disclaimer... I haven't listened to everything exists in this world, just writting my conclusions on all this which apparently evolved around my system and subjective perseption.
A resistive stepped attenuator being the most reasonable choice for me, probabilities to go for an AVC were very thin before this thread came up. Now I feel just a bit wiser... An AVC can have an immeasurable but strong signature just like resistive VC. Also, it can be neutral and transparent. So, what would be the reason to chose it over the other types? Well, the most impressive feature of the AVC in my opinion is its natural ability to match impedance. Just connect I/O and you are ready to go, no calculations involved. George confirmed that it works in balanced mode simply connecting it between hot and cold without any in series resistors to form the so called "U" or "H" shape attenuators. Do that with an ordinary potentiometer... Adding or not its character, it definately retains the sound of the gear it is connected to. I thing this is pricelles!
Ending with the usual disclaimer... I haven't listened to everything exists in this world, just writting my conclusions on all this which apparently evolved around my system and subjective perseption.
Yes, it works. See attachment below for wiring.
An AVC can be calculated, wound and wired in such a way that it's max volume tap is at -20dB (or any other dB number) attenuation.
The attenuation law of all the coil taps can start from there.
So the fixed resistive voltage divider can be removed.
George
