How quiet is quiet?

[Dreadhead]

Hello all,

First a little background: I recently switched to cranking my GS-X up to high gain and then a buddy came over with Edt. 9s I heard hiss (even when the volume is set to zero). I checked and I can't hear the hiss with my HD650, D5000s or SA5000s. I tried my Shure SE530s and the hiss was there with them too. I did all these checks after disconnecting it from my DAC3 at the back of the amp.

On medium gain the hiss is inaudible with the Edt. 9s and slightly audible with the SE530s. On low gain the hiss is barely audible with the Shures when the amp is cranked. This all makes sense since the gain switch is in the feedback loop on the amp so it should drop gain and also cause the amp to be more stable and hence less hiss.

I've spoken to Justin and after a meet this weekend he's going to take a look at the amp. If he doesn't find anything then so be it. My understanding is that Justin's stuff is as quiet as it gets for SS headphones stuff.

I'm just wondering if I'm just expecting too much? I would think you should be able to have a dead quiet amp (with no input) even with SE530s.

I even invested in a PS Audio P300 power re-generator that did lower the noise floor of my setup by getting rid of some transformer noise that my Linn Classik had been introducing to the interconnected system. It unfortunately does not lower the noise floor of the GS-X when it's the only thing plugged in though.

I should add that I want to be able to keep my amp set to max gain etc and use the volume control on my DAC3 since it's theoretically better and any noise should be below anything audible. The noise floor of the DAC3 is below that of the GS-X that's for sure, when you plug it in there is no appreciable increase in the hiss.

[n_maher]

The real question is why are you listening with no source attached?

[luvdunhill]

I should add that I want to be able to keep my amp set to max gain etc and use the volume control on my DAC3

x2 what nate said, and x1 on why would you want to do the above?

[tkam]

Your expecting too much IEM's and other high sensitivity phones will have some level of hiss on all but the lowest gain setting of most amps.

[n_maher]

does the DAC3 have a remote control?

It's listed as an accessory so maybe? If he doesn't require a remote I'd probably run the DAC3 at maximum output and use the amp to attenuate/amplify provided that it didn't overload the input of the GSX and cause it to clip as a result. The output of the DAC3 is a somewhat absurd 4.5V from the balanced outputs.

[tkam]

The output of the DAC3 is a somewhat absurd 4.5V from the balanced outputs.

It's actually pretty common for balanced outs on sources to be in the 4-5V range.

[Dreadhead]

I was listening with no source attached because Justin said that was a good way to test if the hiss is from the amp not from the source. I don't sit there and sit blankly into space

One reason is that the DAC3 has a remote control and also that the DAC3's volume control is much much finer (200 steps, math done at 26 bits and dithered back to 24) than the GS-X. For a long time I listened with the DAC3 set to max output and there is no issue over-driving the inputs.

I forgot to mention I can hear the hiss with my SA5000s on high gain and with the volume cranked but just barely.

I do like having the finer control and not having to put up my recliner when my music goes from modern stuff to (much quieter) classical.

The original switch from med to high gain came about due to me having to apply a about -12 db correction in my DEQ to prevent digital clipping within that unit on more modern songs that have no headroom in the digital signal. I have discovered that this can be decreased to -8db or so without any clipping.

I am expecting too much I figured as much.

[n_maher]

It's actually pretty common for balanced outs on sources to be in the 4-5V range.

I know, but that doesn't make it any less absurd.

Since most balanced amps are going to already have twice the gain of their single ended counterpart it makes little sense to me to couple that higher-gain with a higher output source. I already struggle with a lack of adjustment range.

[n_maher]

I am expecting too much I figured as much.

Not really, I just think you're setting yourself up to fail. Does it really not have enough range if you set the GS-X at the middle range of the pot and vary the volume with the DAC3?

[grawk]

I know, but that doesn't make it any less absurd.

Since most balanced amps are going to already have twice the gain of their single ended counterpart it makes little sense to me to couple that higher-gain with a higher output source. I already struggle with a lack of adjustment range.

Yes, but you listen at levels below the hearing threshhold of dogs.

[Dreadhead]

It's in my nature to obsess about these things. If I know it's as good as it can get then I'm all set and happy again

I have enough range to keep the amp at 3/4 max volume on low gain (no hiss on anything except possibly the SE530s) and still drive the phones to well above where anyone should listen for long periods (though not instant hearing damage levels).

I think I'm still going to send the amp in to Justin because he said too once he heard about hearing hiss with the Edition 9s. I though this was odd but they are sensitive and have low impedance.

[luvdunhill]

I know, but that doesn't make it any less absurd.

Since most balanced amps are going to already have twice the gain of their single ended counterpart it makes little sense to me to couple that higher-gain with a higher output source. I already struggle with a lack of adjustment range.

But, that's 4-5 VRMS from input leg to input leg. So, in a four channel amp each board would see half that.

[aardvark baguette]

I haven't read the entire thread, but I've had the volume on my Dac3 maxed, and fed to either a t-amp or my headphone amp and couldn't hear any hiss with HD650s. I've only powered my e530s once or twice from it, but heard no noise either.

I usually have the volume on the headphone amp or t amp louder than I would normally listen and use the bel canto knob to adjust overall volume, out of laziness. Its usually in the 85-95% range.

There is a bit of hiss from the t amp by itself, that I can hear when everything else is turned off.

[cclragnarok]

I have enough range to keep the amp at 3/4 max volume on low gain (no hiss on anything except possibly the SE530s) and still drive the phones to well above where anyone should listen for long periods (though not instant hearing damage levels).

I think this is what you should do. Just because you are using digital volume control doesn't mean that you have to turn the amp up to max volume.

[Salt Peanuts]

I know, but that doesn't make it any less absurd.

Carys are even worse at 6v range for balanced outs.

[kevin gilmore]

No amplifier is dead quiet.

How much you wanna spend ??

Its this thing called johnson noise and is strictly due to the temperature

of the amplifying parts...

Which is why on my new cryoprobe, the 2 active preamps are cooled to

50 Kelvin. You get about 20db less noise this way.

You can get most of the way there by dumping your amplifier into liquid N2.

[justin]

I think I'm still going to send the amp in to Justin because he said too once he heard about hearing hiss with the Edition 9s. I though this was odd but they are sensitive and have low impedance.

I don't remember saying that. With Shure E530, it's not surprising you'd hear some slight hiss at high gain, but that's why there's low gain. I've never heard of any hiss with a GS-X (except maybe max volume at high gain) with any full size headphone which is why I suggested you send it to me. Only time I've ever had an issue like that was on a prototype GS-X module where the AKG K1000 was creating instability, but only when driven balanced, and it resulted in some hiss

[Dreadhead]

I don't remember saying that. With Shure E530, it's not surprising you'd hear some slight hiss at high gain, but that's why there's low gain. I've never heard of any hiss with a GS-X (except maybe max volume at high gain) with any full size headphone which is why I suggested you send it to me. Only time I've ever had an issue like that was on a prototype GS-X module where the AKG K1000 was creating instability, but only when driven balanced, and it resulted in some hiss

Sorry for my misstatement of what you said. Your reply was "I'd be surprised if you could hear any hiss on high gain with Edition 9s" (which there was when they were balanced, the only SE phones I am discussing are the SE530s) This is all likely due to something stupid I have done to the amp.