Help me understand gain and volume control

tlm · 203

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Offline tlm

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on: April 02, 2024, 01:55:25 PM
I've been considering upgrading my SEX amp to a Stereomour II but just tried an experiment that left me puzzled. I  run a Mac mini to  a DAC with 2.0v output into the sex amp and use the amps volume control. I usually listen with the control at about the 9 o'clock position, turn up to 10 or 12 when I want more oomph but I don't think I gain much after that up to full volume. Today I set up the Audirvana software volume control and ran the sex amp wide open. It SEEMS to have a lot more volume and dynamics and gets louder all the way to the end instead of running out of steam halfway through the volume control. Is it just my imagination that using the software volume gives me more dynamics and volume capability?



Offline 2wo

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Reply #1 on: April 02, 2024, 05:47:41 PM
Probably not your imagination. It's likely Your new setup Simply Outputs more voltage than the probability nominal 2v of your last setup... John

John Scanlon


Offline tlm

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Reply #2 on: April 03, 2024, 01:33:04 AM
Same DAC, same interconnects, the only change is enabling volume control in audirvana and using it instead of the amps volume control.



Offline Paul Joppa

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Reply #3 on: April 03, 2024, 04:40:08 AM
In that case, there should not be any difference in the maximum output. But the relation between the rotation of the potentiometer and the sound level will be different.

Your description suggests the possibility that you have somehow gotten linear pots instead of "logarithmic" pots. An easy check is to set the pot in the center of its range and check the resistance between the center lug and each end lug of one section. Ideally a log pot will read around 10K and 90k, while a linear pot will read around 50K each way.

Paul Joppa


Offline tlm

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Reply #4 on: April 03, 2024, 10:32:24 AM
Thanks Paul! I checked the pot and it is a  log pot. The extra dynamics may be my imagination but I don’t think the volume is. I just noticed that when I set Audirvāna up to control the volume the 24/96 file I am playing goes out to the DAC  at  a higher rate.  Appears that the software upsamples before applying the volume control, could this be the reason for higher volume?  I have been running the volume at about 9:00 and in the software the same level appears to be -35 or so db.  -10 db is  too loud!



Offline tlm

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Reply #5 on: April 03, 2024, 10:33:50 AM
I never thought I’d complain that this amp plays too loud😄



Offline Paul Joppa

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Reply #6 on: April 03, 2024, 11:37:18 AM
Thanks Paul! I checked the pot and it is a  log pot.

Glad to hear that's OK

The extra dynamics may be my imagination but I don’t think the volume is. I just noticed that when I set Audirvāna up to control the volume the 24/96 file I am playing goes out to the DAC  at  a higher rate.  Appears that the software upsamples before applying the volume control, could this be the reason for higher volume?

Could be. It's hard to tell without getting deep into the weeds of what exactly is happening in the software. In any case, if it sounds good it is good!

Paul Joppa


Offline sl-15

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Reply #7 on: April 03, 2024, 03:13:05 PM
What player on your Mac mini did you use before Audirvana?

Stefan Hampel
Soundsmith Carmen, modded Technics SL-1200mkII, Thorens TD 125 mk2 with SME V, Eros, Extended Foreplay III, BeePre2, Crack, Pioneer Spec 4, Sonus Faber Electa


Offline tlm

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Reply #8 on: April 04, 2024, 04:49:30 AM
I’ve been using Audirvāna for a long time but had never enabled volume control in the  software. I’d be curious  to hear what others think after trying it out.



Offline sl-15

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Reply #9 on: April 04, 2024, 05:35:48 AM
I am using Audirvana Version 3.5.50 which is older. When using it it will take over certain system functions and I never noticed the volume function in the settings until a few month ago when I changed my DAC. I now have 'use keyboard to control volume' enabled. Now Audirvana full volume also is the system full volume. Before Audirvana would play at whatever volume I had the system volume set to. It's a bit hard to explain and makes no sense because when you connect a DAC to a Mac the system volume control is disabled and will always play at 100%. The only way to control volume then is through the software you use or your browser etc. BUT let's say I play something through a browser or iTunes and have headphones connected to the Mac and do not use a DAC.  I then can control the volume not just through the software but also through the mac system settings. Let's say I had that set at 50%. Now whenever I would select my DAC again and use Audirvana it would play at the max 50% system volume. Setting Audirvana to 'keyboard volume control keys' fixed this problem and it plays always at 100%. Maybe that is what you are experiencing too?
« Last Edit: April 04, 2024, 06:13:18 AM by sl-15 »

Stefan Hampel
Soundsmith Carmen, modded Technics SL-1200mkII, Thorens TD 125 mk2 with SME V, Eros, Extended Foreplay III, BeePre2, Crack, Pioneer Spec 4, Sonus Faber Electa