[appar111]

I was wondering, aside from not having to turn the volume knob up as loud, what other effects are there when one bumps up the gain on a portable amp?

I have a JMT Pimeta that I have set for a gain of about 3.5 - 4, and this has been great for lower impedance cans such as the KSC-75 and DT770/80. But I'm looking into some other higher impedance cans (around 250 ohms), and I'm thinking if I keep the amp, I should probably get the gain increased a bit. I know this will mean that I don't have to turn the volume up as high as I would with lower gain, but are there any other effects on the sound? Would it also be fuller sounding in addition to making it easier to drive the amp to a required volume?

If I bump up the gain where it should be to drive something like HD600's or DT880's, it may end up being too much for my current cans. I don't know if it will be so much of a problem on my DT770/80's - they may just end up sounding fuller. But would it be too much for other cans like KSC75's, SR60's, etc.?

What would your recommendations be?

 

[gpalmer]

At least theory would suggest that the only difference is that you would not have to turn up the amplifier to the same level and that your volume adjustment would be more touchy. There can be side effects depending on the circuit, for instance I have heard one amplifer with a variable gain which becomes subject to popping noises when the stepped attenuator is adjusted at lower gain levels. Hard to say in the case of your amp since I'm not familiar with it, I would probably ask the builder if any side effects have been noted...

 

[BrokenEnglish]

with the dt880 and hd650 i'm using gain 6 in all my amps. using the emu 0404 at 0dB as source, it allows me to listen to most of my music at 9-10 o'clock. some classical pieces need 12-1 pm. to rock around sometimes 2... but never more. so... that gain setting is pretty universal and leaves some headroom, but i think gain 4 would be enough for most purposes also. personally i prefer that higher gain only to be ready for rolling in opamps that are not unity-gain stable.

good thing with lower gain is (a) lower noise and (b) the pot usually operates most time in secure areas, that means with smaller channel mismatch.

altering the gain is easy with the pimeta. just let the diyer of your choice or the manufacturer socket R4 and provide you with different resistors... you'll be able to change them to your needs/preference in a few minutes then.

 

[gpalmer]

One point that I thought of after my first post is that the volume pots are most linear and best balanced in the middle of their range. So if changing the gain results in you having to use the amp with the volume cranked close to all the way up or down it will tend to show itself as a degradation in the level matching of the right and left channels (and vice versa, if the gain is too low so you have to max your volume...)

 

[appar111]

Quote:

Originally Posted by BrokenEnglish with the dt880 and hd650 i'm using gain 6 in all my amps. using the emu 0404 at 0dB as source, it allows me to listen to most of my music at 9-10 o'clock. some classical pieces need 12-1 pm. to rock around sometimes 2... but never more. so... that gain setting is pretty universal and leaves some headroom, but i think gain 4 would be enough for most purposes also. personally i prefer that higher gain only to be ready for rolling in opamps that are not unity-gain stable. good thing with lower gain is (a) lower noise and (b) the pot usually operates most time in secure areas, that means with smaller channel mismatch. altering the gain is easy with the pimeta. just let the diyer of your choice or the manufacturer socket R4 and provide you with different resistors... you'll be able to change them to your needs/preference in a few minutes then.

My Pimeta was built by JMT, and he has been fantastic to work with. That might be a good idea to have him socket the R4 position. I have found that I get almost no hiss or noise, even at really high volume (with the source on pause of course, otherwise I'd blow my eardrums out!). With my 80 ohm DT770's, I've never gone over 1:00, most of the time the sweet spot is at about 10:30-11:00.

I get no channel imbalance at all, even when I have the volume down around 7:30-8:00.

 

[nikongod]

i find that the same gain works equally for either type of phones. i use the volume knob int he same spot on my senn hd-595's as on my little unworthy harrem of grado/allesandro phones.

i would say see if your present gain works well with your new phones, and your source before you go and have it changed.

 

[Head-Case]

Quote:

Originally Posted by gpalmer One point that I thought of after my first post is that the volume pots are most linear and best balanced in the middle of their range...)

Actually, as most gain controls are set up, they are bast balanced at the very top of their range, where the resistance between the input (top) and the output (wiper) are near zero.

Volume controls are definitely not linear. They conform to a non-linear curve called "audio taper." This makes them easier for us mortals to use. It doesn't matter if they are linear or audio taper as long as both channels track.

Once again, that tracking will be best at the upper extreme assuming the top goes to the input, the wiper toward the output, and the bottom go ground.