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A couple of years ago I started to rip my 2 cases of CDGs over to zipped mp3g format for use with Sax and Dotty's Show Presenter. I have been generally delighted with the changeover to date, but I have noticed lately that with some mp3g tracks, the deep bass notes seem a little broken or distorted. (By the way, I use a good external soundcard - U46DJ).
The problem is really noticeable if the key is changed up or down by one or two steps. The first track I noticed this on was Danny Wilson's ' Mary's Prayer',...on Zoom Hits 002-Track 1. Another would be the Sounchoice version of Don McLean's 'Castles in the Air'.
For some gigs I do, I now use subs and tops. The 'Mary's Prayer' track, raised one step, made it sound like the sub speaker was gone! It was really that bad.
I've paid more attention to other tracks since then, and noticed it on a few more. They all seem to have one common trait,... the use of very low resonant bass guitar notes. The original CDG does not display the problem, and I've also noticed that if I re-burn a cdg from the ripped mp3g files, the problem is not evident on the re-burned cdg played on a JVC CDG player, even with key changes!
I seem to recall a forum discussion some time back, that this could be a problem sometimes with Winamp struggling to handle frequencies below 100Hz, but I can't detect it at all when playing Audio mp3s of the same songs on Winamp.
I've pointed this out to friends, who subsequently confirmed they had the same problem, although they hadn't noticed it until I told them!
Has anyone out there encountered this problem or been aware of it, or aware of any remedy? Thanks.

The compression takes away harmonics esp in the lower bass range. partial cure is less compression or using procs such as the Aphex with big bottom to restore some of them..

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The problem is not the mp3 but the key changer Which key changer are you using

I use the Pacemaker Key Change, as recommended by Sax and Dotty, but am always willing to try different. I should also add that although the key change accentuates the problem, you can still hear the distortion even in the original key.

A friend also tried the tracks on PCDJ FX, which I believe doesn't use winamp, but the distortion was still evident.

What surprises me a little is that if this is a simple fact of life that compression is the cause of the bass harmonics distortion then how come more people haven't raised it. I have found very little info from search engines. Is there a fix to this?

First, don't worry, it's not a fact of live that compressed file do that Now that we know you have the problem on the original key, please tell us which encoder you used to compressed or which software to extract the cdg file and how much is it compressed? An mp3 file encoded using Lame at 160k and higher will sound just has good as the original wave file

Now, for the key changer, they ALL have something wrong, none will play the file properly except the EAX Console from Creative but it's not adapted for reading mp3+g files...

The problem is probably due to a poor encoder used when compressed to mp3

I don't believe that the compression is your problem. The process of digitizing sound by it's nature washes out the bass. There is simply less information in the lower notes. Perfect human hearing recognizes waves from 20Hz to 20000Hz with the low notes being represented by the smaller number. Digitizing the sound is a process of taking instantainious measurement of the sound at specific intervals like little snapshots. So, a low wave at 20Hz(Hz: wave cycles per second) over one second is going to be represented in the "snapshot" by one thousandth the total information of a wave at 20000Hz. So you get distortion and that's just the way the Dipsy Doodle works. If you add a key change which is usually a mathematical process called FFT that sort of smears the sound to approximate a key change, and the lossy psycho-acoustic compression of MP3... There's pretty much no chance that the bass is going to sound like a musical instrument with music taken from a standard 16-bit CD.

Digital audio is not my field so if anyone wants to jump in and correct me please feel free. I will take no offence.

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I have heard poor reviews with Sax and Dotty's over just this issue before, so it may be the application your using.

Also, as you key change there will always be some distortion depending on how far you go. I can't stand a key change beyond 1 or 2 steps in any direction on even the worlds best system, but that's just me.

Have you tried reducing the bass level on the mixer? If your going down on a key that is low to begin with that could cause distortion do to the "unnaturalness" of the attempt sound production.

Compression may also be a factor. Are you using a variable compression or a steady rate, and if so what rate? The minimum constant rate I use is a 256 bit rate, but I prefer 320. Using less compression takes up more room on your hard drive, but keeps the sound quality closer to CD level.

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Good music, good friends, howling good times!

Thanks to all who have responded so far, with quite a variation of opinions.
The specific tracks I mentioned were ripped a couple of years back, when I did not pay much attention to ripper settings. I used Audiograbber at the time, at the default setttings it came with. More recently I have used Power CD+G Burner, again at the default setting, which I have just checked was 128,.....so perhaps I'll try again at a higher setting as suggested. (I don't know if these programmes use LAME)

With regard to the 'unnaturalness' of the low bass sound when lowered further, this is something I have always been aware of, since I used to play bass guitar in a band. This can be noticeable even with non compressed music on a conventional CDG player. However the problem I am experiencing is a definite distortion even when the key is raised.

I have used Sax and Dotty's for about 4 years now, and I find it very easy to use and uncluttered. I don't think it's the programme since the audio is based on the Winamp platform with a Pacemaker plugin. Also, the fact that the distortion was evident using my friend's PCDJ programme, suggests it's more to do with the file.

I think I might pay for a mp3+g download from Zoom, as well as re-rip of my disc at a higher setting. You would think that Zoom would make sure that a Downloaded file would be accurate?

I mean, you would think so, but I have a ton of MP3s I bought from amazon.com that have some audible distortion. I use iTunes with all the DSP stuff turned off except the automatic cross-fader, and it happens in the middle of songs, not during the fade. So although I have not tried listening to the same songs using a different MP3 player, I really think the amazon.com MP3 quality is poor. Who knows if they encode the songs themselves or if it's record labels, etc.

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Jeff Wheeler, moonlight DJ/KJ

Actually, it is the high frequencies that suffer more in the digitizing process. This is because more samples of the sine wave can be taken for a low frequency signal and thus a more accurate representation of the original signal can be reproduced when the player converts the digital information to the analogue signal required by the speakers (not talking about digital speakers here!)

Imagine a sample rate of 2Hz.... that means that only one amplitude value of a 2Hz sine wave can be taken each cycle. However, 2 samples of a 1Hz signal can be taken... ie, the lower the frequency of the signal, the more sample values can be taken and therefore a more accurate representation of the signal.

Ok guys,....another update. I tried ripping at higher settings using Power CDG, but no difference when I played them.
I downloaded yet another programme - Virtual DJ Studio. (I still use Virtual DJ for DJ work but never liked the karaoke facility because the key change was not even near the + or -3 semitone shift range it was supposed to be! - I pointed this out to Atomix, and got a reply saying they would look at it,.....but nothing happened,...so it was no use to me for karaoke.),...anyway,..
Since the newer Virtual DJ Studio prog was a full system 30 day trial, I thought I would try it. After 12 hours of freezes, hang ups and poor guidance notes, and with the help of other karaoke forums, I got it to work reasonably well, but more importantly,....the 'distorted' tracks I had trouble with on the other programmes, played satisfactorily!....Sure, it was not perfect like the quality of the original CDG, but certainly acceptable for a compressed file. Logically, it would seem therefore that my problem lay with the audio players in the other programmes, not being up to the job.
I do feel a little frustrated in that I seem to have found at last a programme which appears to overcome some serious sound quality issues for karaoke, but which for straight karaoke work is far too complex, cluttered and not user friendly. ...Now if only I could merge this sound reproduction, with the abject simplicity of Sax and Dotty Show presenter,....I would have a winner!!!
...Any programmers out there listening?
My ideal system would be something designed primarily for or by a thoroughly professional karaoke host, with an additional facility to play digital music from playlists etc., if required - it may seem sacrilige, but basically ITunes with a crossfade would do the job! As I said earlier, I use Virtual DJ for discos and celebrations, but have never needed or been requested to use the beat matching, sampling and looping facilities. In fact over 20 years I never needed to use this on CD decks and vinyls either.
....ah well,....time to get off the soap box.

Yes, I think I see what you're saying that the longer the wave the more times it is sampled per wave cycle and thus the more accurate the digital representation. However, wouldn't the squaring effect that digitizing has on the wave form tend to cause greater audible distortion and weaking of the overall bass signal when converted back to analog? That has been my understanding.

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Okay, who took my pants?