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Q: High gain? Low gain? Quality difference? - Page 2

post #16 of 22
Originally Posted by Rylo View Post

There's a difference between responding to a question with a question (which wasn't informative at all), and then what you just did, which is to explain why. As a complete noob myself, the rest of the thread explained a lot.


"Hmm... same circuit, a pair of resistors swapped out for another set of different value... question is about "sound quality"? confused.gif"


Sorry, but I know this individual well and he is as knowledgeable as anyone around here..  He was trying to be instructive.  Changing the gain with a set of different value resistors - by definition, has nothing to do with the "quality" of the sound.  Perhaps he should've elaborated, but as I said earlier, the point was well made, IMHO.


Want to change the "sound quality" of an amp?  Then suggest changing the sound-affecting components - capacitors in the signal path, opamps, buffers, transistors (in zero-feedback topologies), etc.  However, changing gain does nothing but change the relative position of the volume knob in relation to the output volume.


Yes, there are instances where the gain may be jacked up enough that it's easy to tell that there's some residual noise or hiss in the output.  However, that is never going to change the sound signature of the amp.


Maybe that explanation helps?

post #17 of 22

Different resistors -> changing feedback loop -> different gain -> different performance (though not by a human-significant amount, especially if not looking at a CMoy or something where you'd be adjusting the gain of the output stage), not just amplifying signal and noise by a different amount.


Sometimes perceived sound quality differences are attributed to more trivial things than this though.


Though really, I wouldn't really expect anything much other than the difference in volume (or noise if you're adjusting volume to compensate).



Anyway, as for things that practically matter, as explained earlier, use a lower gain if volume is loud enough. Avoiding a hypersensitive and possibly channel imbalanced range of a volume control is a good idea. If you never listen that quietly with whatever source output level and headphones you're using, yet you don't hear any noise from the amp, then it's probably all moot.

post #18 of 22

sorry for resurrecting a very old thread.


Traditionally I was always wary of using high gain. First reason was raising the noise floor, but I remember reading (of course I can't find it now) that different gain setting change the inductance (?) of the output. One of my amps is the Marantz HD-dac1 and I think it was in that amp's forum that people where explaining this. It has 3 gain settings. And while something like the HD650 will work on any of the 3 gain settings it matches for example the middle gain setting better. I have no idea if this is true or the science backs this up. When people start talking about the math behind driver/amp impedance, phase, voltage needed to drive the coils vs watts, my head starts to hurt. 


From my experience: 


With something like the O2 amp if you put headphones in (and no signal) and crank it it to max on low gain, you will hear noise. It was explained to me by JDS, that yes the 02 is "silent" but only up to something like 100dB or 105dB, which realistically is pretty much max safe listening levels and If you are listening to Skrillex at 105dB, you are not going to be bothered by a tiny bit of noise. ANYWAY, turn the gain up on the 02 and this noise floor raises. Not really a big deal, and probably still not noticible under actualy listening condition (i.e., music), but it was one reason I never wanted to use high gain on amps. 


I just got my hands on the Valhalla 2 and I was running HD650 on low gain, I was listening to 90% power/volume on a few songs. The thing was running HOT! So I was thinking maybe I should run these on high gain instead. 


Did a bit of testing. Crank the Valhalla 2 up to 100% volume on low gain, no noise. High gain? No noise at 100%.


High gain it is for me with Valhalla and HD650. 

post #19 of 22

(Running on a Fiio E10k :P)


High gain is mostly used for a power hungry headphone, such as the AKG Q701 for example. If your amp is not powerful enough to drive the phones on L gain, then switching to H gain will add more volume. Be warned, the sound will start to distort at higher volumes on high gain, and you can actually run the risk of damaging your headphones.


So you wouldn't use something like a pair of M50s or Sennheiser HD598 on high gain, cuz it doesn't need it lol, and it'll probably cause some damage. 


In terms of sound quality, as I said before, it'll distort at higher volumes. Try testing the sound if you want, you'll probably hear little to no difference.

post #20 of 22
A potentiometer is nothing but a variable resistor... High and low gain set the starting point for this resistance using static reisitors before the pot takes effect..

Think of a pot as a water faucet... You turn it on and you get water... The pressure is determined by how much you turn the knob.. Now think of the static resistors (high and low gain) as the valve under your sink.. If you turn that valve down.. You will limit the amount of pressure you can get from your faucet using the knob.

Now think about that and then come to your own conclusion on if this would effect sound quality, outside of the beginning noise floor :P
Edited by kejar31 - 6/24/16 at 6:21pm
post #21 of 22

This looks like an old thread--not sure anyone is still watching. However, last weekend I went through quite a lot of testing of gain vs sound, and found surprising results.


The reason was that I had purchased a used 2012 v.2 Matrix M Stage HPA-1 headphone amp/preamp, and was shocked at how good it sounded when I dropped it into my system (used as a preamp). I had purchased it to use in a desktop system I'm setting up for my brother, and had no intentions of using it my own desktop system--but after auditioning this thing, I realized that it would be perfect for my own system, so went out and found a really cherry 2013 HPA-1 for a routine test, expecting it to sound the same as the 1st one--but to my surprise, it was somewhat brighter (unwelcome IMO)...and seemed to require more rotation of the volume pot to get equivalent volume.


So I flipped the units over and compared gain settings (the HPA-1 has a 3 position gain setting for each channel: 0 dB; +10db; or 20dB). As it turns out, due to the very confusing labeling of the gain switch diagram, when I'd set the switches on the 1st unit, what I thought was 0 dB for each channel (ie, the lowest gain setting) was actually +20dB (maximum gain). By contrast, the second unit actually WAS set at the lowet gain setting.


So purely by accident, I discovered that the highest gain setting sounds slightly "warmer" (ie, less bright) than the lowest gain setting on the HPA-1. Bearing in mind that the HPA-1 is a relatively warm/euphonic HP amp/preamp to begin with, and that the amt of "brightness" I'm talking about is relatively small--it was still a surprising result, the reverse of what one would expect.


As mentioned earlier in this string, higher gain should theoretically be associated with lower noise; and to whatever extent circuit noise correlates with brightness, I would expect there to be less brightness at the lowest gain settings.


I'm still puzzled by this...

post #22 of 22

Weighing in from an audio engineering perspective - if you're working with an "active" system vs a "passive" one, gain will introduce more electricity into the signal, effectively "amping it up", more electricity introduced to the signal = more saturation / distortion.


So not only will the perceived noise floor be raised, the tonal characteristics, saturation / distortion, and harmonics will also be affected.


Additionally you may notice an increase in low end / mud as these frequencies require more electricity to be driven effectively - so there could be a loss of "clarity", but added warmth.

Edited by Seasho - 7/28/16 at 8:24am
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