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Rockbox and crossfeed

post #1 of 33
1/4/07 at 2:53am
Thread Starter 
I loaded up my ipod with rockbox and was playing around with the settings the other day and realized that it has a crossfeed option. Could someone explain to me exactly what crossfeed is and what it does and how it might be beneficial to me? It also has high-frequency attenuation, not sure exactly what that is either.
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post #2 of 33
1/4/07 at 8:14am
You will find a brief description here.
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post #3 of 33
1/4/07 at 11:15am
Thread Starter 
Interesting to say the least.
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post #4 of 33
1/4/07 at 11:24am
Quote:
Originally Posted by spiN View Post
Interesting to say the least.
Ditto that. Learn something new every day. I never had any clue this was even an issue.
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post #5 of 33
1/4/07 at 11:31am
You can also find a description of crossfeed in the Rockbox Manual: http://download.rockbox.org/manual/r...ml#x9-850006.7

This includes a description of the crossfeed options available in Rockbox.
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post #6 of 33
1/4/07 at 2:37pm
Does the Rockbox crossfeed function perform well, or is an amp with crossfeed circuitry better? Also, does the "EQ" in Rockbox solve the ipod EQ problems?
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post #7 of 33
1/4/07 at 2:46pm
I feel compelled to chime in here...

A crossfeed circuit in an amp I suspect is pretty much guaranteed to perform better. I have no first-hand experience with this, but it seems logical to me. Plus, I wasn't overly thrilled with the Rockbox crossfeed function in some (perhaps isolated) instances. I was playing a FLAC file from Strapping Young Lad - The New Black that caused some ugly bass distortion. Once I turned off the crossfeed, there were no problems. It's a neat feature, but I consider it to be an unnecessary gimmick.

And what EQ problems do you have with the iPod?

-Packgrog
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post #8 of 33
1/4/07 at 3:42pm
Quote:
A crossfeed circuit in an amp I suspect is pretty much guaranteed to perform better. I have no first-hand experience with this, but it seems logical to me. Plus, I wasn't overly thrilled with the Rockbox crossfeed function in some (perhaps isolated) instances. I was playing a FLAC file from Strapping Young Lad - The New Black that caused some ugly bass distortion. Once I turned off the crossfeed, there were no problems. It's a neat feature, but I consider it to be an unnecessary gimmick.
I would wholly disagree with the above post. I love crossfeed on my Rockboxed iHP140, and I have it switched on all the time. I have a crossfeed unit for my home rig too - but it's not as good as the digital version and I never use now.

Perhaps this has something to do with it being easier to target the correct frequencies and amount of frequency to cross feed digitally than it is with electrickery - I don't know.

Pluck
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post #9 of 33
1/4/07 at 6:35pm
I don't agree at all that a crossfeed circuit hardwired in an amp will necessarily be better than that in Rockbox. No logical reason why that must be true although I won't deny the possibility that some amps might in fact have a better crossfeed.

The crossfeed in Rockbox is excellent and one of the main reasons that I can't go back to the iPod OS. The fact that you can configure it with great precision is one of the best features. Here are my settings (which I have posted before):

Rockbox Crossfeed:
direct gain -0.5dB
Cross gain -6.5dB
High frequency attentuation -6.5dB
High frequency cutoff 700 HZ

By comparison with the default settings, I think you will find that this has much less influence on the frequencies and relative volumes of both the centre and corners of the soundstage while creating a very effective crossfeed effect.
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post #10 of 33
1/4/07 at 6:45pm
If you were deaf on you're left ear, how would crossfeed really affect anything?
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post #11 of 33
1/4/07 at 9:41pm
Quote:
Originally Posted by Packgrog View Post
And what EQ problems do you have with the iPod?

-Packgrog
Distortion!
One other query - Does Rockbox offer a "pan" function. Thanks folks, I really appreciate your input.
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post #12 of 33
1/4/07 at 9:47pm
Quote:
Originally Posted by Kasp3r View Post
If you were deaf on you're left ear, how would crossfeed really affect anything?
Yes. You'd hear more with your right ear regardless of whether you're deaf or not.
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post #13 of 33
1/4/07 at 10:16pm
Quote:
Originally Posted by jmmtn4aj View Post
Yes. You'd hear more with your right ear regardless of whether you're deaf or not.
More detail?
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post #14 of 33
1/4/07 at 10:41pm
Quote:
Originally Posted by Kasp3r View Post
More detail?
Crossfeed is mixing a little of the right channel into the left channel, and vice versa. In many studio recordings, for example, you'll hear a guitar playing in the left channel, for example, because they assume that you use a speaker to play that track, and so your right ear will still hear the sound being outputted by the left channel. When you use headphones, and you can't hear with your left ear, you don't hear the guitar at all.
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post #15 of 33
1/5/07 at 2:10am
Quote:
Originally Posted by Honus View Post
Distortion!
One other query - Does Rockbox offer a "pan" function. Thanks folks, I really appreciate your input.
There is balance control and also choice of channels (Mono Stereo Left Right) including a custom control that allows you to manually specify the stereo width. "All values below 100% will progressively mix the contents of one channel into the other. This has the effect of gradually centering the stereo image, until you have monophonic sound at 0%. Values above 100% will progressively remove components in one channel that is also present in the other. This has the effect of widening the stereo field. A value of 100% will leave the stereo field unaltered." (Quote from the manual which you can download.) Lots of options for someone who is hard of hearing in one ear but not a pan control per se.

The control of hardware EQ in Rockbox for the iPod solves the EQ distortion problem for increasing bass at lower frequencies. (I agree that iPod OS EQ control is unlistenable). The software EQ is also meant to be good for controling a broader range of frequencies and you can create your own settings. I don't use it because I only want a mild boost in gain below 105HZ where Rockbox direct control of the iPod's Wolfson DAC is wonderful.

Be warned that battery life will be awful and this will be a problem when you discover how much better your iPod sounds Rockboxed. It's hard to go back.
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