21 replies to this topic

[superVT]

yes we've heard this many times before ..

but how exactly does the gain mechanism work as compared to a volume control mechanism?!?

i want technical details not just "gains is there to match voltage outputs and volume control makes it louder"

there is no hiding the fact that gain control DOES make the speaker go louder but how does this differ from making the speaker louder through a volume controler.

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There were 7 dwarves ..... They were all feeling happy ..... So Happy got out!

[JohnA]

The way i look at it is like this:
Take the old cassette deck that had recording level controls....the higher you set this level the louder it will record, but if it went to the red your recording would be distorted.
So the recording level was there so you can get the maximum level off any source without it been too low or too high (distortion)
Well an amplifier gain control is pretty much the same thing.
Yes it will go louder as you turn it higher but that is to compensate for the lower levl HU's (same as an original low recording)
If HU has a high pre-out, then for the amp to reach it's max output the gain would not require to be as high..(loud original recording, record levels set much lower)

Hope this made sense, or i'm not ralking a load of crap.

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/////ALPINE CDA-7939E / CHA-S624 / PXA-H600 / DDW-F30A
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I'm as confused as a baby at a topless bar
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[Mr_Bob]

If you have the highest pre-out voltage the amp can handle (not necessarily what it's rated for)
then when your Hu is set to maximum volume, the amplified signal is at it's loudest undistorted point,
if you turned teh gains up,
the amplified signal would distort earlier, so you'd hit maximum undistorted amplified signal, before your HU was at it's maximum setting.
therefore it doesn't control volume.
if you set the gains too low, it will mean that the HU will never be able to send a signal strong enough to turn the amp all the way up. In this way it can limit volume, which is where the misconception is.

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'96 Mirage
Rockford RFX9300 deck
Rockford FNP 2614 splits (soon to be rear fill)
Alpine MRP-T130s front stage amp (soon to be rear fill amp)
What?no subs?
Waiting to be installed: Focal 165W3's
Vrx 2.150 & 1.500
TEAM Audison
Another ANTI Team Craig David Member

[Cyberpunky]

Gains beimg *turned up* doesnt make it louder at all, it makes it louder at lower volume setting. As Bob points out, having gains *turned up* will just make amp reach full output sooner, but it wont and cant make amp go any louder or system, it will just mean your volume control hass less range, as it will push amp to max output sooner than if set proerly, which will allow maximum range of volume control to be used. It will also allow you to drive amp into distortion, which wont happen if set correctly.

peace
Cyberpunky

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[shiny_car]

quote:

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Originally posted by Cyberpunky:
Gains beimg *turned up* doesnt make it louder at all, it makes it louder at lower volume setting. As Bob points out, having gains *turned up* will just make amp reach full output sooner

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yeap, think of it as a 'sensitivity' control. gains 'up' means more sensitive.

as CP point out, an example would be:
*gains down: volume setting on HU 35/40 produces full output from amp
*gains up: volume setting on HU 10/40 produces full output from amp

in the second example, you obviously have far less fine control over the volume but the end result is the same maximum power output from the amp. of course the second example also poses a higher risk of clipping the amp because one would mistakenly think there's much more 'volume' left to play with...wrong!

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/////ALPINE audison DYNAUDIO polkaudio OPTIMA Stinger LIGHTNINGAUDIO

[Stone]

Anyone who was already confused, please don't read this

So in theory, you could do it in reverse and set your head unit volume at one point and use the gains as the volume? I know this would be totally pointless and not be very practical if you had multiple amps, but it is correct, right?



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My system under construction...
Head Unit: Pioneer DEH-P9450MP
Front Stage: Infinity Kappa Uniplane 80F 8" midbass & Morel Dotech 4" components
Sub: Adire Audio - 15" Brahma
Front Amps: Pioneer GMX-962 (2 x 125W) & PPI 2360 (2 x 90W)
Sub Amp: JBL BP1200.1 (1 x 1200W)

[mirage]

yep, you could do it that way if it did it for you

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teamazm.com -Australia's premier modified cars website

Try before you buy, and do it right the first time...

[Stone]

Thought so... So both controls are exactly the same, they are just used in a different way. Call them volume, call them gain, or input sensitivity... They are still the same thing, just used differently.

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My system under construction...
Head Unit: Pioneer DEH-P9450MP
Front Stage: Infinity Kappa Uniplane 80F 8" midbass & Morel Dotech 4" components
Sub: Adire Audio - 15" Brahma
Front Amps: Pioneer GMX-962 (2 x 125W) & PPI 2360 (2 x 90W)
Sub Amp: JBL BP1200.1 (1 x 1200W)

[mirage]

well, i am not 100% on the workings of a headunit but i have always thought that they are basically the same thing, however as the input signal level the HU feeds to itself internally from a cd is pretty much set, the manufacturer can vary a pot (volume control) between known values to vary the output of the amp within safe operating regins with perhaps small level distortion at full volume.

The input signal level to an external amp is unknown to the manufacturer however so the pot can be varied between loosely chosen values which could easily cause a distroted output if matched with an incorrect input signal level, that is why it is best to level match your gains for undistorted output on the amp, and leave the volume control to the HU.

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teamazm.com -Australia's premier modified cars website

Try before you buy, and do it right the first time...

[superVT]

quote:

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Originally posted by Stone:
Anyone who was already confused, please don't read this

So in theory, you could do it in reverse and set your head unit volume at one point and use the gains as the volume? I know this would be totally pointless and not be very practical if you had multiple amps, but it is correct, right?

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finally!! .. someone who knows what i'm getting at!!

i know what gains are for .. don't get me wrong ..

and when i say you can use the gains to make speakers go louder .. i don't mean max dB that the system can reach .. i mean (and there's no denying this) then when you put the gain up and down .. the volume out of the speaker goes up and down!

i wanna know is what is the difference (if any) between the MECHANISMS within volume control as opposed to gain controls. or as mirage noted .. are they the same thing?!? .. just has different purposes.




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There were 7 dwarves ..... They were all feeling happy ..... So Happy got out!

[shiny_car]

quote:

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Originally posted by Stone:
Thought so... So both controls are exactly the same, they are just used in a different way. Call them volume, call them gain, or input sensitivity... They are still the same thing, just used differently.

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to convince others (ie: newbies) that they are the same is only asking for trouble. the functions of the volume control on your HU and the gain are obviously different. we should not be creating false 'myths' that they do the same thing!

to my knowledge, the volume control works like a potentiometer (variable resistor). low volume settings means the signal passes through high resistance so little signal passes out the preouts. higher volumes reduces this resistance and more signal passes through.

indeed some gains are designed in a similar manner, in that the are simply a potentiometer. 'gains down' (less sensitive) provides more resistance so less signal passes on to the amp section; and vice versa. however, i believe not all gains are made this way.

so always think of them as having totally different functions, even though they may work on the same principle.

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/////ALPINE audison DYNAUDIO polkaudio OPTIMA Stinger LIGHTNINGAUDIO

[Konrad]

quote:

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Originally posted by shiny_car:
to my knowledge, the volume control works like a potentiometer

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Actually, it is my understanding that the volume control on most decks these days is in the digital domain, no an analog pot based volume control? Anyone confirm this?


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[Stone]

quote:

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Originally posted by shiny_car:
so always think of them as having totally different functions, even though they may work on the same principle.

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That's all I was saying...

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My system under construction...
Head Unit: Pioneer DEH-P9450MP
Front Stage: Infinity Kappa Uniplane 80F 8" midbass & Morel Dotech 4" components
Sub: Adire Audio - 15" Brahma
Front Amps: Pioneer GMX-962 (2 x 125W) & PPI 2360 (2 x 90W)
Sub Amp: JBL BP1200.1 (1 x 1200W)

[Bassaholic]

why should you bother with 2 volume controls, when it is easier to use just one???



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- A proud member of Team Gates

[doober]

In the end, the output signal is analogue so there has to be SOME analogue stage at some point.
Your HU's volume control would not be so crude as to use voltage dividers (inaccurate and wasteful), many DACs actually have volume controls built in (it's pretty neat what some audio chips can do very easily) and i'm not entirely sure since alot of companies like alpine actually seem to have their own custom IC's (or at least they painted over the old labels ) but basically i would have thought they would be small amplifier circuits gain controlled (digital amplification would seem much too much effort to me).

I think one of the few differences between the gains and your HU's volume that i can grasp fully is that if you turn your gains up too high with your HU volume set to 'half' you'll be putting out your amp's max power (clipped too). But if you turn up your HU volume too high with your gains set to 'half' (so full HU volume = half max amp output signal) then you'll only be putting out a fraction of the amp's power. So your gains would be more critical to correct system performance as they have the last say in the range of the output (although settings your gains too high just means you have a reduced HU volume range before clipping).

It's all stuffed up anyway, it should be digital/encoded 99% of the way :P

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.
Modified 1986 Series 4 RX-7 Turbo II
Soon to be:
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[Edited 1 time by doober on 01 July 2002 at 22:21]

[shiny_car]

quote:

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Originally posted by doober:
Your HU's volume control would not be so crude as to use voltage dividers (inaccurate and wasteful), many DACs actually have volume controls built in (it's pretty neat what some audio chips can do very easily) and i'm not entirely sure since alot of companies like alpine actually seem to have their own custom IC's (or at least they painted over the old labels ) but basically i would have thought they would be small amplifier circuits gain controlled (digital amplification would seem much too much effort to me).

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yeah, i figured my suggestion was a little archeic.

given that the tuner must also pass via the volume control, not likely to be digital is it?

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[KDog]

Most volume is controlled digitally but the signal is still analogue. The volume changing chips usually take in a serial word (usually from a digital pot or push button through a transciever) which then determines the level of its output signal.
The signal travelling through the chip is still analogue and this process usually takes place one stage before the RCA outputs and after the DAC.

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Never argue with an idiot.
They will bring you down to their level and then beat you with experience.

[shiny_car]

sweet. thanks kdog.

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/////ALPINE audison DYNAUDIO polkaudio OPTIMA Stinger LIGHTNINGAUDIO

[doober]

That's still analogue amplification though, just in fixed steps digital amplification would be a numerical adjustment to the samples, most likely just by a scaling factor (this is where it might get complicated as it might be a logarithmic scale which is why i said it would be alot of effort Plus the fact that it would add noise due to having no overhead ).

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.
Modified 1986 Series 4 RX-7 Turbo II
Soon to be:
Hertz 2x(HT25, HV100, HV200L) + HS300 (2cf, 35Hz)
Response 5ch amp (3x200W)

[mirage]

quote:

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Originally posted by enzo:
someone correct me but shouldnt a balance be struck betwen amp and units. Instead of one up one down why not a balance. Isnt it possible for decks to clip out rca leads when turned up

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the only way the balance you descibe could be acheived is if you are prepared to go to you boot to alter your amp gains every time you adjust you HU volume.....why no just leave the amp matched to the maximum input signal and adjust the input signal for voume reasons.


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teamazm.com -Australia's premier modified cars website

Try before you buy, and do it right the first time...

[Cyberpunky]

if you set volume at 10 and then turn up gain, it will be louder at that volume setting, than if gain set lower (dah), but that does not make gain a volume adjustement, as any amp only puts out X power, and so adjusting the gain only determines the point at which it reaches full out put, and so saying that turning up gains makes it louder is wrong, as it can only go so loud and if you crank gains it just gives you less volume range, as it doesnt and cant go louder, it can just get there with less volume setting or before maximum volume setting.


If you set it so you can turn deck to maximum undistorted out put, you have greater range to set the volume just right, but if you crank them, you have less margin to play with and so just reach maximum quicker, meaning you have less range and are less likely to get the perfect adjustment for all conditions, as lower range means less steps in volume level.

Anyway if getting full volume at 5 on volume impresses you, and so having 5 steps from nothing to full suits you, and also that you will never need to go above 5, then do it, but you cant make something out of nothing, and so NO your gain isnt a volume, it just determines how much range of adjustment you have and more range is usually good, as is setting things so you cxant try and exceed max outut, as trying to get more sometimes ends in smoke
peace
Cyberpunky

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"Electricity is for more than powering windmills" Ali G
"Out beyond ideas of wrong doing and right doing there lies a field. I'll meet you there." Rumi
"forget the specs, and just listen to what is watt" Cyberpunky
"These answers you get, couldnt they be your own signal, bouncing off some object in outer space, some other planet, boomin back atcha???" Freq Nasty
All your base are belong to us! ;)
Like to know more? click here
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