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In Reply to: RE: Volume vs Gain posted by davidandcandy@gmail.com on August 11, 2015 at 12:29:26
I believe volume is the SPL (sound pressure level) at the listening position.Gain is the amount of voltage difference between the input and the output of a circuit. ie; 1 volt in, 10 volts out would be a gain of 10. That also can be expressed as a gain of 20db.
The gain needed to give the desired SPL (volume) is subject to many things.
The efficiency of the speakers being used, for one.
The sensitivity of the power amp (how many volts in for a given power level) if you are looking at the needed gain of a preamp, etc.
The gain of a preamp is lowered when you turn down the volume control. The stated gain of a preamp is only realized when the volume control is turned all the way up.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Edits: 08/11/15Follow Ups:
Isn't it true that an AMP is generally FIXED gain while the VC simply acts to attenuate the INPUT signal to the amp? A VC acts as a simple voltage divider, right? So the amp simply adds its 'gain' to whatever the input voltage happens to be.
Too much is never enough
Exactly....generally.
In the end there are many ways to skin a cat.
I believe there are circuits where the "volume/gain" control changes circuit components around a stage that actually changes the gain of that stage vs. just simply attenuating the signal directly.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
My PSAudio integrated was billed as 'Variable Gain' and used proprietary input circuitry called 'Gain Cell'.
However, I believe this to be HYPE (No relation to HYPEX) since the amp used essentially unmodified B&O ICE Modules.
I know the INPUT section of my PARASOUND amps (A23) use an attenuator (100k, per Richard Schramm) which I'm DYING to replace with a 6 position Stepped Attenuator using 1% (or better) 1/4 watt film resistors. I believe the improvement will be small, but real over the carbon film pot used.
Too much is never enough
Let me know if the stepped attenuator improves sound quality from your Parasound Halo A23. I've got the Halo A21 and my attenuators are set about half way. If you get a noticeable improvement, I might just make a simple voltage divider from a couple of precision resistors. I don't really need a stepped attenuator.
Thanks,
John Elison
YOUR suggestion was my FIRST idea. But, no reason to sacrifice the feature.And from our FWIW department, Richard Schramm thought it was a decent idea and would result in a slight help. I'd say that YOU are in a better position to judge given that in my case the pot is OUT of the circuit since it is at 'max gain' position. However, I DO want to turn it down a few db so I'm up in the 'sweet spot' of the preamps gain range.
Since I don't have a schematic, I do NOT know if the controls is a single gang applied between the balanced/ single ended input AND the amp OR somehow they use a stereo version and use one section of the 'stereo' pot for balanced and the other for the single ended.
DO YOU KNOW?
I'd bet that both the '21 and '23 use the same system / circuit at that point.
PM me if you would like to SHARE? I could use some help should I decide to go with the 6 position GoldPoint switch. I think THAT would be where I'd like to 'land'..
I'd need help in resistor selection since I have no idea how to relate DB to resistance. All I know is that it should sum to the total of the current pot which I think is 100k if I remember correctly from my post to Richard……..
Now that I think about it, I don't need more than 9 db of TOTAL attenuation. That means I can turn it down 3db and have space on either side in just the switch I specified.
Too much is never enough
Edits: 08/12/15
I don't know what type of potentiometer is used. You would have to open it up and take a look -- possibly make some measurements. I guess you will need to figure that out before you buy a stepped attenuator. My system sounds real good with the stock potentiometers so I probably won't take my amp apart anytime soon. However, if you modify yours, I'll be interested to know what you discover.
Thanks,
John Elison
I won't do much of anything without 2 things.
First: a Schematic would be nice
Second: Figure What resistor net would give -1.5 db per step for 6 stepsI just had an Idea! I'm going to look at and download some interior photos. Maybe, if the pics are of sufficient resolution I can SEE the pot and at least see what Type it is.
A quick look at BOTH the '23 and the '21 shows a single gang, 3 wire 'pot' on each channel.
It is wired into a sub board with what LOOKS to be a few additional resistors. I can't tell.The next issue, due to the sub-board below each pot would be one of SPACE for which accomodations may need to be made.
As it turns out, the GOLDPOINT 24 step 'mono' attenuator is less expensive than the 6 position switch would be after adding resistors. the Stepper comes with 0.5% resistors and at the top to middle of the range features 2db steps. Perfectly fine. The KNOBS are expensive, though at 15$ to 19$ EACH. It is a non-standard (1/4"= standard) shaft size, so watch out.
If there is enough space, this would be the obvious way to go. At about 200$ per amp!
Too much is never enough
Edits: 08/13/15 08/13/15
I sent a note to Richard S requesting a schematic or just that part which shows the input circuitry.
Next step would be to open the case top and take a few measurements. See IF what I propose will FIT.
After that? If all goes well, I've got to RATIONALIZE about 200$ per amp in 'upgrades'.
Too much is never enough
That's a lot of money for a modification that might not sound any different than the stock potentiometer. Before I spent that kind of money, I would set the pots to the volume level you require. Then remove them and measure with an ohmmeter. Buy some quality resistors and install a cheap voltage divider. Leave one of your amplifiers stock and compare the sound quality.
My gut says it isn't worth $400 to modify two amplifiers but it might be worth installing simple voltage dividers. In other words, you might hear a slight difference but you might not be able to tell if it's better or worse, or just different. Moreover, even if you determine it to sound better, it might not sound enough better to justify spending $400. Of course, if it sounds significantly better and you want to install the stepped attenuators, then you've spend only a few extra dollars on the simple voltage dividers.
Good luck,
John Elison
But…….But……But…..
It's ONLY money!
I might add, in all honesty, that the divider was the recommended 'fix' IF I could decide on a single setting. I was also told to expect 'some' improvement.
Too much is never enough
Edits: 08/14/15
Tre', thanks for the explanation of gain which is what I asked for. Having said that, maybe I'll rephrase it to ask, if I'm actually smart enough to form the right question, how is the gain set in relation to the volume, or am I incorrect in my assumption that they are related in listening. Do I set the gain at one point & leave it? Does the setting of the gain change with different listening sessions, or with different sources, such as cd's or vinyl, and if so, how do you know where to set it? I hope I've asked the right things, but even more, I hope I understand the answers! Dave
Everyone thinks I'm strange except my friends deep inside the earth
Gain is usually a term applied to amplifiers. Gain limits the current such that the amp doesn't have its full potential available. Many stand-alone amps don't have gain controls, which means the full power is always available based on the feed it gets. With a gain control you can dial back the amount of output on the amp. Why would you even want to limit it? I'll come to that.
Volume controls how much of the potential output from your sources you want to let pass through through to your amp.
Think about the amount of available water pressure you have in your home. If you have alot that is akin to a powerful amp. If you use a very small diameter hose to wash the car you have cut the "gain" of your water flow.
Whatever the maximum flow might be given your water pressure and hose diameter, turning the spigot is akin to adjusting the "volume". Volume controls are limiters. When turned fully up, no limit and you'll get the maximum available.
It is often useful to have both volume and gain controls. This is more the case when you have a powerful amp or very sensitive speakers. Let's use the case of sensitive speakers. Turning the volume just even a little bit might yeild a big difference in volume such that using a volume control with a remote might be difficult to make tiny volume adjustments. By reducing the gain you can "swing" the volume control more and achieve the same volume adjustments.
Many preamps are said to give their best sound when the preamp is allowed to use a fair amount of it's own gain. This requires the volume control on the preamp to be in its mid range or higher. That might provide too much overall gain to the amp and be too loud. If the amp has a gain control you can dial back the amp's gain so that the preamp can operate in it's sweet spot and you will have the ability to use a fair amount of swing with the volume control. It takes some experimentation to discover the best combination of these settings.
Long time ago I had a Audio Refinement amp that had a gain control - one of the most useful features I have ever had. Could easily dial in the volume "sweet spot" using a combination of the gain control and the overall volume setting.
"Volume controls are limiters."
That is true only in the context you're using it.
In the professional world a "limiter" in not just a volume pot.
A limiter allows the engineer to limit the loudest part of a music signal leaving the rest unchanged.
A similar tool is a compressor. With a compressor an engineer can limit the loudest part, just like a limiter, while increasing the level of the softest part of a music signal.
A volume control decreases all parts of the music signal equally.
"Many preamps are said to give their best sound when the preamp is allowed to use a fair amount of it's own gain. This requires the volume control on the preamp to be in its mid range or higher. That might provide too much overall gain to the amp and be too loud. If the amp has a gain control you can dial back the amp's gain so that the preamp can operate in it's sweet spot and you will have the ability to use a fair amount of swing with the volume control. It takes some experimentation to discover the best combination of these settings."
Been there, done that.
Wouldn't it be better to design the total system (preamp, amp, speakers) that doesn't require a large amount of attenuation?
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
You don't set gain. Gain is the maximum amplification of a device. You use the volume control to adjust how much of that amplification you want to send to the next device. Gain is fixed. Volume goes from zero gain to maximum gain or anywhere in-between
Alan
I think where my confusion started was when I saw that the remote for my integrated amp had a button for increasing/decreasing gain as well as the typical volume up/down. This started me wondering where I should set the gain and do I change it at any particular time. I had never had an amp that gave me that option & wasn't sure what to do with it.
Everyone thinks I'm strange except my friends deep inside the earth
"I think where my confusion started was when I saw that the remote for my integrated amp had a button for increasing/decreasing gain as well as the typical volume up/down. "
To answer your question I would have to know more about your integrated amp.
I found this,
"Pressing the Gain button toggles between 0dB and -8dB settings. If you have source components with widely differing output levels, the -8dB setting will allow the louder source to be brought closer in volume to the quieter. I used only one source, so I listened at the 0dB setting."
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Yes the variable gain adjustments are if you have several devices connected to your pre or integrated you usually can adjust the gain for each input so at the same volume they will all play at the same loudness
Alan
Some of the old tube integrated amps had "trim pots" close to the inputs, designed for that same purpose.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
The gain of a given circuit is whatever is is.A volume control is just a voltage divider. Some of the signal voltage is lost across a resistor and turned into heat.
When you lower the volume control you are lowering the total system gain. That lowers the SPL (volume) in the room.
A phono cartridge has a very low voltage output so the phono preamp is meant to increase that voltage to match line level signal sources (CD player, etc.).
I hope this helps.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Edits: 08/11/15
nt
try it! you know you want to!
Thanks, but I was trying not to confuse the issue that the original poster is asking about.
I use an AVC.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
I consider *gain* to be additive (such as a gain stage), while *volume control* is something that is subtractive (such as a resistive potentiometer, or variable digital audio output level control function).
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