While my Cambridge Soundworks system *seems* to do justice to the 128/44 MP3s at the house, I was just wondering when you got into a more enveloping environment of a car if you started to hear compression artifacts and such.

Should one expect CD quality? Something a little less? Assume too that I'm talking about a fairly well recorded CD to begin with that's been ripped.

Would a person notice in an "eyes closed" test, the difference between an MP3 playing on an Empeg and the actual CD itself?

Thanks,

Jambo
Something like #14000 (give or take a few)

It depends who you ask.. Search for mp3 compression on this BBS, this topic has been covered in detail before - BUT - most people claim they can't tell a 128kbs mp3 apart from a cd.. Personally, I can.. I've encoded most of my music at 160kbs Variable, and have a difficult time telling this apart from cd's..
-mark

...proud to have one of the first Mark I units

Hm. I've been doing 128 constant. Should I be recording with VBR?

- Jon

Hm. I've been doing 128 constant. Should I be recording with VBR?

Yes. I recently switched from 128 constant to VBR, and it's much better to my ear.

If you take two MP3 files of equal size, one of them at 128 constant and the other one at VBR, the VBR will have less artifacting in the high frequencies.

Tony Fabris
Empeg #144

To start off with, let me clarify something: You're asking two completely separate questions. I'll tackle them separately.


Q1) Independent of the artifacts inherent with low-bitrate MP3 compression, how does the quality of the Empeg's audio circuitry itself compare to other consumer audio cicuitry?

A1) The Empeg has excellent audio circuitry. The reproduction of the sound is quite detailed and compares favorably to in-dash CD players costing $500.00 or more, and sounds much better than just about any computer sound card.

There is one issue that's unique to the Mark 1's (i.e., you won't have this problem with the Mark 2 when you get it because they fixed the problem): Ground loops. The Mark 1 used a "floating ground" system, which, if you didn't have things hooked up and adjusted in a certain way, could cause some electronic noise in the very low volume noise floor. What this meant is that the Mark 1's noise floor was higher than many other consumer audio components. Like I said, they have solved this problem with the Mark 2's, so you will get a very low noise floor- probably much lower than your amps' noise floors and definitely lower than the noise floor of your computer's sound card.

Depending on how noisy your car is and the quality of your amps and speakers, the improved detail of the Empeg's audio circuitry (when compared to your home computer's sound card) will allow you to notice MP3 compression artifacts that you didn't notice before. That's what happened to me. I had some 128kbps MP3's that I was satisfied with- until I played them on my car system and could hear them in more detail. I've been slowly going through my collection and re-ripping the more troublesome songs with VBR compression instead of 128k-fixed.


Q2) Independent of the audio circuitry, how does MP3 compression affect the quality of the music?

A2) This has been discussed in detail elsewhere on the BBS. The general consensus is:

- At 128kbps fixed bitrate, most non-audiophile listeners can't tell the difference between the MP3 and the original CD. However, on some songs, certain high-frequency pink noise (like cymbal crashes) will sound "swishy" or "crackly" instead of smooth, as if they were being played from a cassette tape that's wearing out. An audiophile will usually notice these artifacts right away in a blind test. A non-audiophile could be taught to easily recognize these artifacts if given the proper examples.

- At 160kbps, those artifacts start to go away, and at 192kbps and up, even most audiophiles can't distinguish the difference between the original and the MP3.

- Variable Bit Rate encoding allows you to combine the best of both worlds: the smaller file size usually associated with 128k-fixed MP3s, but the higher quality associated with higher bitrate files for the frames that really need the extra boost in resolution. As I mentioned before, I have been re-encoding some of my 128k-fixed files into VBR files and I'm quite happy with the results. You can adjust the VBR quality-to-file-size ratio: the ratio that results in VBR files that are equal in size to 128kbps-fixed files will sound much better than the 128k files.


In the end, combining both your questions back into the original single question:

Provided that I've encoded the songs properly, I can't tell the difference between the MP3s on the Empeg and the original CDs played in a good CD player.

Tony Fabris
Empeg #144

Variable Bit Rate encoding allows you to combine the best of both worlds: the smaller file size usually associated with 128k-fixed MP3s, but the higher quality associated with higher bitrate files for the frames that really need the extra boost in resolution. As I mentioned before, I have been re-encoding some of my 128k-fixed files into VBR files and I'm quite happy with the results. You can adjust the VBR quality-to-file-size ratio: the ratio that results in VBR files that are equal in size to 128kbps-fixed files will sound much better than the 128k files.

Ok, now that I know what VBR is (hehe... was asking this in another post until I saw your post and then I deleted my other one)... What are some good encoders that can do VBR?

Kureg

Pardon my ignorance, but what is VBR?

Variable Bit Rate. It's available with some encoders (such as Xing's).

MP3s are divided into frames, small sections of music representing about 0.026 seconds of audio data. Each frame is independent of the others. So somebody got the bright idea: If each frame is independent, why does the entire MP3 file have to be at the same bitrate?

VBR allows you to have "simple" frames (ones where the audio frequencies aren't complex) encoded at a low bitrate, while "complex" frames (such as those containing lots of overlapping high frequencies) could be encoded at higher bitrates. This results in a file that has a higher percieved quality than a fixed-bitrate file of the same size.

Oh, and I record my MP3s at 192. I know it might be a little overkill, but I am certain I can't tell the difference between it and CD quality. It still compresses to an acceptable level for me (around 7:1 as opposed to 10:1).

192kbps is certainly very high quality, and nearly impossible to distinguish from the original source (I know I can't tell the difference). But consider this: To me, a VBR file that compresses at around 9:1 or 10:1 sounds equally as good as that 7:1 fixed-bitrate file. You might want to check out some VBR encoders and see if they give you the results you want for a savings in file size. Depending on how much you want to spend on disk drives, you might need the savings.

Tony Fabris
Empeg #144

Ok, now that I know what VBR is (hehe... was asking this in another post until I saw your post and then I deleted my other one)... What are some good encoders that can do VBR?

I'm happy with AudioCatalyst. It uses the Xing encoder. Xing loses to Fraunhofer in quality tests at 128k fixed bitrates, but the VBR encoding more than makes up for it. Fraunhofer can't do VBR to my knowledge. Plus, Xing's encoder is lightning-fast.

Audiocatalyst's "Audiograbber" ripping engine isn't as good as some, but it gets the job done for most people.

Tony Fabris
Empeg #144

i personally now rip at 160. A few years ago , 128 made sense because of limitations on Hard drive storage. Now with the advent of consumer offline storage (zip , cd-burners , orbs ,etc) and larger HD space (40 gigs costs $230)
you can store tons of mp3s at 160 or even 192.

I think you can tell the difference on a lot of songs with clear vocals , horns and symbols etc. You hear the difference at home if you have a good audio system for your mp3s and in the car on the EMPEG.

on the whole , the EMPEG plays a lot better in the car and in the house than most other units. I sometimes play my music from the EMPEG in the house. I only switch back because i can only hold 10 gigs on my EMPEG right now , and i have more than that on the computer. I need 40GB's on the EMPEG!

I use Audiograbber on top of the Fran codec. I like the interface of audiograbber , and the options. Try it out , i find musicmatch , too busy.


Empeg Kicks Ass
S/N 00203
http://www.iretro.com