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streaml1ne
2005-12-09, 21:24
I noticed bass on the headphone out was fairly non-existant on bass heavy tracks so I created a test tone from 20-400Hz and played it through the SB3. I recorded the output on my minidisc recorder's line in and noticed a pretty significant rolloff. The input signal was -6db across the sweep. The headphone output is shown in the attachment. I tried searching for this problem but haven't found anything. Is this a hardware/firmware limitation or something that can be fixed in software?

tyler_durden
2005-12-09, 22:26
How do you know you're not seeing a roll-off in the MD recorder's response? Recorders are often made with low freq roll-off to reduce wind and mic handling noise.

If you want to measure it accurately, all you need are a few fixed frequencies in the desired range, a load resistor, and a medium quality DMM or voltmeter.

Turn on a tone, and measure the voltage. Change the tone and measure again, ad nauseum. Most DMMs will handle AC up to a few hundred Hz without any accuracy issues. If you use a sine wave output you don't need an expensive true RMS meter.

TD

pfarrell
2005-12-09, 22:35
On Fri, 2005-12-09 at 20:24 -0800, streaml1ne wrote:
> I noticed bass on the headphone out was fairly non-existant on bass
> heavy tracks

Did you try different headphones?
Headphone output are really not line out, your SB3
has some real headphone outs on the back. One of
the serious EEs can talk about how the impedance mismatch
may impact the frequency response. I'm not
sure how accurate your MD test is since they
all use a lossy compression to the media.


--
Pat
http://www.pfarrell.com/music/slimserver/slimsoftware.html

seanadams
2005-12-09, 22:53
uh - what are hms? Is that the time for the sweep?

Would like to see Hz on the X axis...

Anyway I don't think the headphone amp has enough power to drive real strong bass into low Z. But with a light load I would not expect a huge roll-off...

streaml1ne
2005-12-09, 22:56
I've measured the minidisc's line in frequency response from other analog sources with the same sweeps and it's pretty consistent down to 20hz. If I go optical into my AVR and set the tone controls flat I get full bass response. When I plug the phones in directly to the SB3, I don't. If I have to I'll pull out my oscilloscope and test, but I'm pretty confident the recorder is showing me what I'm hearing. Here's output with the same sweep recorded from the RCA outs on the SB3. If it were the minidisc recorder the rolloff should be the same, no? The headphone out recording shows a much more drastic rolloff.

streaml1ne
2005-12-09, 23:03
On Fri, 2005-12-09 at 20:24 -0800, streaml1ne wrote:
> I noticed bass on the headphone out was fairly non-existant on bass
> heavy tracks

Did you try different headphones?
Headphone output are really not line out, your SB3
has some real headphone outs on the back. One of
the serious EEs can talk about how the impedance mismatch
may impact the frequency response. I'm not
sure how accurate your MD test is since they
all use a lossy compression to the media.


--
Pat
http://www.pfarrell.com/music/slimserver/slimsoftware.html


All of these test recordings are linear PCM, newer Hi-MD recorders use it natively. The input files to the SB3 were WAV.

streaml1ne
2005-12-09, 23:08
uh - what are hms? Is that the time for the sweep?

Would like to see Hz on the X axis...

Anyway I don't think the headphone amp has enough power to drive real strong bass into low Z. But with a light load I would not expect a huge roll-off...

The sweep is 10 seconds in length. I don't think Audition will let me show X in Hz. The headphones themselves are MDR-SA5000's which present a 70-ohm load. The minidisc player itself and a pocket c-moy amp have no problem driving them. I definitely noticed the lack of bass immediately though. It's not too big a problem since the bulk of my listening would be through my AVR anyway, just thought I'd bring it up.