[viper32]

I was wondering if some of you out there that own a Headroom Micro amp. If you have a high noise floor (hiss) or what you would call excessive with IEM's.

I was using mine with the UE5c's last night and with no source connected and the volume all the way down I could here a prominant hiss, which got louder as I turned it up. When I listened to music I could here it in the background at times during the songs. This is with the gain setting at low. I do realize that this does happen with low impedance phones. I tried the amp with my HD650's and it was dead silent due to the 300ohm load.

Just to give an example with my Hornet (gain low)and the UE-5c's the noise floor is much lower and is very hard to hear.

Any info from some current owners would help.

 

[TheSloth]

The micro shouldn't hiss even with that impedence. Make sure your gain was set to low. Even so, it shouldn't be noticeable. I strongly suggest you contact HeadRoom support, who will help you out with this.

I've owned just about every HeadRoom amp, and the only ones that hiss with low impedences are the airhead and bithead models.

 

[viper32]

Thanks for the reply. I had called Headroom yesterday before the post. Tech support guy said he had tried his micro and some superfi's and he could hear some slight hiss, he said that this was normal for low imp, phones. FWIW, He also said that the hiss would be more noticeable with phones of about 70ohm and lower. He had suggested 200ohm inline attenuator might solve the problem.

This is why I posted to see what other owners had experienced with this amp and the low imp phones.

 

[SiBurning]

Wish I could get a proper impedance chart for these. Here's the crummy specs I have and the results my ears reveal. Westone UM2, 27 Ohms. Shure E5c, 110 Ohms @ 1kHz. Etymotic ER-4P, 27 Ohms.

With the MicroAmp running off batteries, volume all the way up, with the television on at a soft-to-medium speech volume... Westone & Shure hiss noticably at all gain settings.

Etymotic only has noticably audible hiss at high gain, but the hiss is still barely perceptible at other gains, if inaudible practically speaking. For example, although I probably couldn't tell what or where the sound was, I do notice when it's switched on or off, even on low gain. Turn the television off and the hiss is audibly noticable at any gain on the Etymotics.

An inline attenuator does lower the hiss and the volume in gerneral, but so does the inline attenuator built into the Micro Amp, the difference being that the one inside doesn't also change the tone. Another difference being the built-in attenuator doesn't alter the volume of the hiss nearly as much as the music, so at extremely low listening volumes, the onboard attenuator might allow you to raise the music volume way above the noise, and then the offboard attenuator will allow you to cut them both down to listenable levels.

As for hiss with volume all the way down... I didn't even think of testing that first time through. Yes, the hiss sure is there. It gets louder as the volume control is turned up, but doesn't get amplified nearly as much as the music. The hiss is still quite noticable at extremely low volume levels. The music also comes through a bit with the attenuator all the way down, and at this level the volume of hiss is competing with the music.

 

[edmoses]

I have a Headphone Micro and Etymotic ER-4P earphones. I get no hiss with this combination using batteries or the DPS. I have been using this combination for a couple of weeks (upgraded from a Total Bithead) with no noticable problems.

Regards,

Ed
(apart from a lighter wallet that is...)

 

[TheSloth]

I'm still surprised by this. I'll go back and test my module roller with the micro, desktop and home modules and my ety 4p's, which at 27ohms should show up any hiss. I know it's not a micro, but I can't see any reason why the Micro would have a higher noise floor, and running off batteries, it should indeed have a lower noise floor. Unless there is something in the design I don't know about.

What module do you have in your Micro?

 

[viper32]

Quote:

Originally Posted by TheSloth What module do you have in your Micro?

I have the Desktop module.

Here sre the specs I found on the UE-5c.

119db/1mw
Frequency Response: 20 Hz to 16k
Impedance: 21-ohms
Driver: Dual Driver: Single Hi/Single Low
(Balanced Armatures)

Passive crossover
Extended headroom 124db/mW

 

[sidewinder]

is this only on actual 'headphone' amps? cause I don't have any hiss on my home amp combined with the ER4P/S

 

[jeffc]

Quote:

Originally Posted by viper32 I was wondering if some of you out there that own a Headroom Micro amp. If you have a high noise floor (hiss) or what you would call excessive with IEM's. I was using mine with the UE5c's last night and with no source connected and the volume all the way down I could here a prominant hiss, which got louder as I turned it up. When I listened to music I could here it in the background at times during the songs. This is with the gain setting at low. I do realize that this does happen with low impedance phones. I tried the amp with my HD650's and it was dead silent due to the 300ohm load. Just to give an example with my Hornet (gain low)and the UE-5c's the noise floor is much lower and is very hard to hear. Any info from some current owners would help.

I own a UE10 and Headroom Micro (desktop module) and I also hear some hiss. Just like your setup, the hiss is volume dependent. I've tried using this amplifier with some cheapie headphones and have not heard any hiss with those combinations. The UE10's sensitivity is also 119db/mw. With pop music, the volume knob is between seven and eight o'clock. With classical music, the volume knob is between eight and ten o'clock.

The hiss isn't terribly annoying. At work, my computer's fan and my coworker's noises are louder than the hiss (even when wearing the UE10's---26db of attenuation can't quiet a 45+ db fan).

You may want to return the amplifier if it's too loud, try adding an inline attenuator, or try not to focus on it.

As a side note, I've used Ety ER4P (and S with 75 ohm resistor) and can hear a slight hiss, but for me to hear it, but I need to be in a quiet room.

Jeff