Help explaining how my valve phono stage works

[paulf-2007]

While my main stage is away being modded/repaired I am using the old faithful Yaqin ms-12B.
I was running vinyl into phono stage, then 0.7v out into Dac/preamp, using the volume control on the preamp and USB in to the Dac from Spotify. That was until a friend suggested using the yaqin's volume/gain control instead of the Dac/preamp volume control. Still don't understand the difference between volume and gain, laymans terms please if anyone would like to explain. What I found using the yaqin stages control is that the bass is overpowering, some would like that but it's too much. I tried the 0.25v and it sounded better if a little bass light so 0.5v output would be right going by my own logic. When using the control on the yaqin with the Dac/preamp controlling volume I can adjust the yaqin to suit the cart in use.
Now, while the yaqin is being used as a preamp, controlling volume, I am running line level from the dac to the cd input of the yaqin and tried both the 0.7v and 0.25v outputs I preferred the 0.7v. This may make sense as the PX25 mono's have 700mv input sensitivity.

This may need several reads to make sense of my inarticulate writing.

I do wonder if the control on the yaqin is for the phono part of the circuit for cartridge matching and not as a volume control for the preamp stage. I don't have a circuit diagram to hand to post but will try to find one, not that I could make sense of it. I am relying on the expertise here.

[Jazid]

Hi Paul :-)
The difference between volume and gain is easy: volume has a knob that goes from 0-11, gain has a scale that works in decibels. They both control how lloud the music is, but volume is a consumer term, gain is a technical term usually (but not necessarily) related to the ratio of voltage out divided by voltage in, across whatever stage is being measured.
In a volume control pot the maximum volume is with the pot fully open and the gain is thus 0dB as there is no gain. With the volume turned down the signal is attenuated so the gain is negative.
Why on earth either should make your bass balance vary I cannot say, sounds squiffy to me. Circuit diagram might help perhaps?

Sent from my GT-I9195 using Tapatalk

[paulf-2007]

Thanks James, that's clearer. Yesterday I swapped it all around to how it was before, cartridge to phono in and phono out, either 0.25v or 0.7v to Dac/preamp line input, then out of Dac/preamp to power amps. With the yaqin volume control maximum and out of the 0.25v and adjusting the level on the preamp up and down buttons sounds best. Out of 0.7v bass is overpowering.
What I would really like is a stage to match the Shure Ultra 500 with jico stylus with adjustable loading. Any suggestions welcome.
Oh and James you are very welcome to come here anytime.

[struth]

By sounds of it, one is doing the amplification at the source, while the other is doing it after. Usually it is much better to do it at source, ie, the phono stage

[Arkless Electronics]

You can change/add input loading capacitors for cartridge matching.

Changing output level does not boost or cut the bass.... unless somethings very wrong and that's extremely unlikely.

[dave2010]

Surely volume and gain are roughly equivalent, in layman's terms at least. An amplifier usually provides positive gain - and yes - it is often measured in decibel's because otherwise the numbers would be too big. An attenuator gives negative gain.

There are different ways of doing gain control. A simple approach would be to use a fixed gain amplifier, and then dump energy so that most of it doesn't actually go to the desired load (e.g. a loudspeaker). That would be very wasteful, and if anything went wrong, could lead to disaster. Might be a useful approach in cold climates for room warming.

Another way is to control gain with negative feedback, but that could lead to high frequency oscillations - though feedback gain control is used for some circuits - probably not normally for volume controls.

Surely the normal way to do volume control, is to have effectively a pre-amp stage to boost signals up to a modest level, then to dump the energy from there (not a lot) and then do the large scale amplification using a power amp. Using voltage dividers with high value resistors will hardly waste any energy in the pre-amp stages. The circuit designers will decide where to put the voltage dividers.

If the input signals are very low level (e.g satellite dish receivers, or pickup cartridge outputs) then it makes sense to apply some gain before attenuation. Keeping noise levels down is important at this stage, otherwise noise will be amplified later on.

If all the circuit components are linear, and wide bandwidth, then the total gain is simply the sum of the dBs: +ve for amplification, and -ve for attentuation.

If digital amplification is used, then different techniques can be used, and some circuits use a combination of analogue and digital techniques.

[Arkless Electronics]

Surely volume and gain are roughly equivalent, in layman's terms at least. An amplifier usually provides positive gain - and yes - it is often measured in decibel's because otherwise the numbers would be too big. An attenuator gives negative gain.

There are different ways of doing gain control. A simple approach would be to use a fixed gain amplifier, and then dump energy so that most of it doesn't actually go to the desired load (e.g. a loudspeaker). That would be very wasteful, and if anything went wrong, could lead to disaster. Might be a useful approach in cold climates for room warming.

Another way is to control gain with negative feedback, but that could lead to high frequency oscillations - though feedback gain control is used for some circuits - probably not normally for volume controls.

Surely the normal way to do volume control, is to have effectively a pre-amp stage to boost signals up to a modest level, then to dump the energy from there (not a lot) and then do the large scale amplification using a power amp. Using voltage dividers with high value resistors will hardly waste any energy in the pre-amp stages. The circuit designers will decide where to put the voltage dividers.

If the input signals are very low level (e.g satellite dish receivers, or pickup cartridge outputs) then it makes sense to apply some gain before attenuation. Keeping noise levels down is important at this stage, otherwise noise will be amplified later on.

If all the circuit components are linear, and wide bandwidth, then the total gain is simply the sum of the dBs: +ve for amplification, and -ve for attentuation.

If digital amplification is used, then different techniques can be used, and some circuits use a combination of analogue and digital techniques.

Cambridge Audio (70's) and Musical Fidelity both used that regime in some models;)