Macbook Pro Penryn Headphone Output Noisy??

Hi All,

Long time mac user here. Just upgraded my 2.16 to a base model Penryn 2.4 MBP.
I'm a composer and live with my headphones on my head and plugged into either my ipod or my computer.
I am very alarmed as to the high level noise floor on the headphone output, i mean it's not a huge amount, but considerably more than previous models.
When audio is not being played for some time, the noise literally 'clicks' off and then on again when you playback....
Completely not good enough for a 'Pro' machine in my opinion.

Also, the drivers for XP are absolutely horrific. I'm getting horrible digital artifact noise and a much more shocking noise floor compared to OSX.

any others with the same experience?

thx
Stu

bobcan said:

This is likely an Impedance mismatch... my SR MBP has this issue, and it can be "solved" be inserting a Device that is used for Airline Audio Outputs (Shure/ Ultimate Ears/ and other Pro Audio manufacturers) make an In Line Device which has an Attenuator (fancy word for Volume Control) so you can better match and Raise the s/n (Signal to Noise) Ratio accordingly...

Here is such a device, known as a Shure EA650; it will work with pretty much any 1/8" (3.5mm) headsets I am sure :

"Shure offers this level attenuator to reduce the level of incoming signals and allow for precise volume adjustment, minimizing background hiss...."

http://shure.com/PersonalAudio/Products/Accessories/CasesAdapters/us_pa_pa235_level_attenuator

Click to expand...

Thats actually a good idea BW. It does indeed sound like quantization noise to me, as in, I don't think the analog output is being adjusted per se, just the level of digital audio hitting the D/A converter is very very low, so essentially, I'm using only a few of the lowest bits in the converter (which makes me worry about the audio quality)... so most of us think the output is being turned down, but no, in fact... just less digital info is getting to the converter.
I'm using HD-25 sennhesiers @ 70 ohms, so they are quite low impedance compared to other headphones and require less volume ouput generally. The unit you've linked me to would be a good start to find a solution, now I can run the output at a nominal volume and use the bulk of the D/A resolution at the same time. Still, I never had an issue with my powerbook G4, 2.16 was worse, this 2.4 is kinda appaling. I'm using an mBox2 for ProTools work, and my lord, it's like night and day between the circuitury of that and my MBP.

found another thread with this same problem so might close this off
thx

https://forums.macrumors.com/threads/443692/