[dwarfed centipede]

I know Flac is lossless, but how big a difference is there between these 2?  If you don't have $1000+ audio components, will you even notice anything?

Also, I have been trying to figure out if the metal spikes on the bottom of sub boxes are really needed.  I have my sub box on the carpet, and my surround speakers on top of it with the little rubber pads.  What exactly will be the benefit of putting spikes on the bottom of the sub boxes?  They are made from 3/4" mdf and thoroughly braced.  I hardly feel any vibrations when I put my hand on the side while playing and it doesn't ring when I knock on it.  Thanks.

[bpape]

The idea with the spikes is to keep the whole box still to maximize clean output by the driver.  The box, as is with no spikes, is subtly sliding along the carpet back and forth in opposition to the driver movement.

As for the mp3 at 320, to me there is a lot of difference.  On all 3 of my systems, it's very discernible. 

Bryan

[BradJudy]

Just rip a good CD into both FLAC and high quality mp3 and see what you think.  It's easy to try it out for yourself and you'll have an answer that's right for you.

[dwarfed centipede]

So with the spikes, I will have more bass?  Will it be cleaner?  I still don't quite understand why the box moving slightly corrupts the sound.

[bpape]

Think about it.  If the woofer is trying to move forward in relation to the box, but the box is moving backward, you're not getting as much excursion.  Also, since the box isn't going to move perfectly in time with the driver, when the driver comes back, the box is still going back for a while, then coming forward, etc. 

Spiking the box will keep it sitting still so the driver is the only thing moving - which is the way it should be.

Bryan

[dwarfed centipede]

But these are both very minimal.  We are talking 1mm or less.  Is this even noticeable?  I mean with all things perfect, Im sure I would be able to tell.  But not in a room cluttered with chairs/tables/lamps/etc.  I bet moving a table from 1 side of the room to the other will have more of a noticeable effect than spiking the box.  Thanks for the clarification.  I will probably end of trying this just to make sure I can't tell, if there a cheap and easy way to try this?

[EDS_]

But these are both very minimal.  We are talking 1mm or less.  Is this even noticeable?  I mean with all things perfect, Im sure I would be able to tell.  But not in a room cluttered with chairs/tables/lamps/etc.  I bet moving a table from 1 side of the room to the other will have more of a noticeable effect than spiking the box.  Thanks for the clarification.  I will probably end of trying this just to make sure I can't tell, if there a cheap and easy way to try this?

As mentioned rip a CD with the same song in MP3 at various kbps rates and then FLAC.  Then decide for yourself.


The spike thing is easy - spikes help a lot making a very noticeable positive difference in sq.

[bpape]

But these are both very minimal.  We are talking 1mm or less.  Is this even noticeable?  I mean with all things perfect, Im sure I would be able to tell.  But not in a room cluttered with chairs/tables/lamps/etc.  I bet moving a table from 1 side of the room to the other will have more of a noticeable effect than spiking the box.  Thanks for the clarification.  I will probably end of trying this just to make sure I can't tell, if there a cheap and easy way to try this?

1mm on a driver that may have 12-15mm of excursion is a significant percentage.  Even forgetting that, in the grand scheme of things, there are a lot of things in audio that make a lot of difference for a tiny change. 

What if a speaker cabinet was 1mm narrower or wider?   

What if a tweeter was 1mm bigger? 

What if a signal in your components was .01V hotter at one frequency? 

The list could go on and on.  The whole idea of a speaker in a cabinet is for the DRIVER to move in response to an electrical signal and do so accurately.  If the box moving is adding to or subtracting from that movement, you're not getting accurate reproduction.

Bryan

[dwarfed centipede]

good perspective.  I never looked at it that way before.  But I don't agree on the 1mm on the speaker cabinet part.

[Rashiki]

I know Flac is lossless, but how big a difference is there between these 2?  If you don't have $1000+ audio components, will you even notice anything?

You know, I've been curious about this. At RMAF, I went to a talk where John Atkinson generated a "difference track" and played it for us. The track was the difference between an uncompressed piece of music and the same music compressed to 128 kbps MP3. After the talk, I asked him if he had tried it with a higher bitrate and he said that he hadn't, so I decided to try it someday.

For my sample, I took a 1 minute segment of Tchaikovsky's Marche Slave. The segment has a lot of dynamic range, going from very quiet to near peak within the minute. The music was ripped from CD using EAC. I've made the segment available here: http://0xf2.com/sample.flac

Next, I saved the segment as 320 kbps MP3, then converted the MP3 back to uncompressed data.

Then, using a handy tool, Audio DIffMaker from Liberty Instruments http://www.libinst.com/, I generated a difference track. The result is available here:
http://0xf2.com/difference.flac

I wasn't surprised to see that the results were similar to what John Atkinson demonstrated at RMAF. Of course, MP3 is based on the principle of frequency masking -- your brain ignores frequencies that are close together -- so, while the difference track does represent the information that is lost, it may not be audible. Of course, MP3 is based on the frequency masking of the "average" person, so some people may hear more of a difference.

Anyway, I hope that helps.

 -Rob


 

[JoshK]

I agree with Rashiki that its a falacy to think because you can hear the difference track that you could hear the difference between the two unaltered tracks.

I think that it is music dependent and not just musical style dependent.  I have a few songs that I have found over the years that the mp3 compression does weird things to, for example AC/DC Hell's Bells.  The opening guitar riff is almost inaudible in the mp3 compression version (using hof and lame and a couple others I've tried). 

There are other tracks where it tends to kills the beauty of the tone.  That is the best way I can describe it.  Its like it makes the tone flat.  Then there are plenty of songs, maybe the majority where it is damn hard to tell the difference.

For me, I don't want to be bothered with mp3, when space is so cheap, unless it is for my portable.