• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required as is 20 years of participation in forums (not all true). There are daily reviews of audio hardware and expert members to help answer your questions. Click here to have your audio equipment measured for free!

Volume control topologies

MingChops

Member
Joined
Jun 3, 2020
Messages
38
Likes
29
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
 
F

freemansteve

Guest
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.
 
OP
M

MingChops

Member
Joined
Jun 3, 2020
Messages
38
Likes
29
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
 
Top Bottom