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Volume control topologies

MingChops

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Jun 3, 2020
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I have a question on volume controls, not being an engineer I don't really understand the technicalities with respect to pro's and con's of the different designs out there.

I've orded a new Pre-amp, a Schiit Freya S, and I am curious if it's Relay-Stepped Attenuator design is 'technically' better or not than my current Pre-amp?
My current pre-amp (Audolab 8300A, an integrated but I operate it in Pre-amp mode) uses what they call a Logarithmic Ladder Volume.

Circuit diagrams, and by that I mean looking at google images seem to be relatively similar (as I said I'm no engineer!), but I am curious to know if either is technically superior or if they are in effect the same design?

Give the Audiolab doesn't have a clicky volume from relays, I'm wondering if architecturally they are similar but the Audiolab is using a chip/transistors rather than relays as in the Schiit?
The Audiolab also has a digital read out of the volume in dB scale, likely facilitated by being a chip design?

Cheers
 
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freemansteve

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You seem to be talking about a bunch of switched resistors versus using potentiometers, for a volume control. And yes, there are also "pulsed controls" that just signal a change to a processor which then changes the volume electronically for you.

Religious views abound, as there are good and bad implementations of both the mechanical designs. I prefer the pulsed sort for a knob, and a remote control, but of the mechanical types, the switched resistors only give you a number of volume settings as opposed to being infinitely variable between min and max, but that may not matter. Pots can often be a tiny bit mismatched - you have to use them as a ganged pair - although I've never noticed this, it is certainly measurable. I don't really like the feel of a switch to change volume myself.

The other point is log versus linear - most vol controls are logarithmic as far as I know, as this appears to the user as a similar angle change anywhere on the knob has a similar effect on volume, and similarly a switched resistor control will usually use resistors that have a logarithmic changes. It does not have to be log though, whether switched or pots. With a pulsed control, the designer can programmatically make the actual volume change steps anything he likes.

Honestly, don't worry about tech superiority for a volume control - any half-decent manufacturer will have controls that work fine - the rest of the amp design is more important.
 
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MingChops

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Jun 3, 2020
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I don't believe either the Schiit or Audiolab use pot's, which is why I was wondering how similar their designs are, or not?

Your last sentiment is very much correct of course, but whilst I wait for shipping I have a touch of buyers remorse!!
I'll get it installed, listened to, and compared within a couple of days, and by that point as long as I'm happy then the topic of volume control will indeed be a 'moot' point......(yes corny pun!!) :D
 
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