Trouble EQ'ing left channel to match right channel?

I have an audio file digitized from 1/4 tape, it’s from a radio archive pre-FM, the left channel is less bright sounding than the right, I’ve tried EQ’ing the left to match the right
but still sounds less clear. The best I’ve been able to get it sound is using stereo expansion eg. inverting/exchanging layering over original file, I just can’t get it right with EQ alone…
Could somebody please have a go at trying to ‘correct’ the left channel (whatever process you think it takes, it may be more than just EQ), and tell me what you did if you were able to ‘fix’ it?, it would be very much appreciated!
Attached in this post are 3 different 6 second .WAV samples as suggested by Steve, also here’s a full song .WAV download link if anyone prefers to check it out as a whole song file, link will expire in 6-7 days:
The 3 different song samples should require the same adjusting as each other as they’re all part of the same concert file.
Sample #1

Sample #2

Sample #3

Thanks in advance for any help!

Possibly they are mid & side rather than left & right.

If that is the case you need a decoder. e.g …
voxengo MSED.png

Hi, Thanks for your reply…
Unfortunetly I only have Audacity and Adobe Audition 1.5, is there a way I can use a decoder like that without buying a new program?
About the file you’ve changed, it does sound better, bass has become clearer, but I’m not sure it’s correct, as in the sample you posted you can hear a drum pad trigger “swoooosh” sound is very buried under the music, in the 80’s and 90’s radio broadcasts that drum pad trigger “swooosh” sound was
coming clearly from the left channel, so I don’t think it’s quite the right ‘mix’ you posted, even though sounds better than my raw file!
For your comparison, here’s the same song taken from 1981 radio broacast old cassette tape, this is how the instrument placement mix should sound:
And here’s again is my raw ‘muddy sounding’ file that needs brightening up:
Thanks again in advance for any advice.

The Voxengo MSED plugin is free, no strings attached.
The 32-bit VST* version is compatible with Audacity in Windows. (There is also a version for Macs).

[*VST not VST3]

While you’re there get a copy of Voxengo GEQ which allows you to adjust the EQ of each channel independently in real-time


Thanks, after a while of playing around with this I think it’s the best I’ve had it sound…, it’s creating a very similar sound I was getting when using a “stereo width expansion” process and “stereo field rotate” and creating a mixdown file, but this sounds more correct, more full and balanced in both channels.
If this is a mid-side recording, what is the purpose?, I believe it was originally mixed to stereo in 1981 from multitrack, would it have been mixed/mastered to mid-side? if it’s mid-side would it then be decoded to left-right for radio broadcast like the radio broadcast sample I posted? I’m just confused about how/why it would be mid-side as I’m really only familiar with L+R !

Is there a way to do this mid-side panning on the fly, or at least hear more than 6 sec samples?

Thank you very much!!!, I really appreciate !!!, this is a great help!

I don’t know about Mid-Side. There would be no reason to want that and that would have been pretty cutting edge back then.

I think it’s much more likely it’s a four-channel tape, stereo this direction and stereo that direction, and you’re listening to tape edge damage, or player head misalignment.


For a “quick and easy” fix you can get quite close by applying the “Bass and Treble” effect to the left channel only, with “Treble” increased to +24 dB and the other sliders at 0.0.

With plugins & some Audacity native effects, (like bass & treble),
it is possible to adjust the parameters whilst the track is playing,
i.e. in real-time, as if it the plugin was a physical device
[ In practice there is some latency, less than a second, rather than 6 seconds ].

When I first heard the file, my first thought was the left channel was suffering from digitization with bad tape head or something, but I don’t know enough about tape to be sure… If it is tape edge damage or player head misalignment as you say will this left-right pan fix it?, it seems to be making it sound quite a lot better than anything else I’ve tried! What will happen if it’s tape edge damage?, what part of the sound will tape edge effect? As I’ve said before it seems to be the left channel that’s muddier sounding, but seems to clear up with some of these panning and EQ processes I’ve been trying, but that may be the muffled sound is just being covered by the less muffled right channel, I’m still trying to work it out!

Also a nice improvement, sounds very good with some EQ, thank you!
Is there a way I can find the details of what the actual adjustments that treble EQ preset is applying?

There’s some information in the manual here:

Thanks Steve, my old PC I don’t change things on anymore which I’ll be working at this afternoon in some spare time isn’t the current Audacity, will this bass & treble change to treble make the same levels adjustment on older version Audacity?, I’m not sure if maybe you’ve updated the levels it adjusts in newer versions.
Also you said increase treble +24, but the slider does not go up to 24, however I can type +24 into the box, I presume that is OK?
Thanks again!

The “Bass and Treble” effect is the same now as when I first wrote it :wink:

I edited last post as you replied…
So I’ll ask here again, you said increase treble +24, but the slider does not go up to 24, however I can type +24 into the box, I presume that is OK?


How old is the version of Audacity that you are using?
Audacity’s built-in “Bass and Treble” effect was added in it’s current over 5 years ago, and the slider range was +/- 30 dB, as now.

There was an even older version that had slider ranges of +/- 15 dB which I wrote around 2013. You’re not still using that version are you? :confused:
If you are, then to get +24 dB boost, apply it twice with +12 dB boost each time.
As far as I remember, the filter characteristics of that ancient version were the same, but with a smaller range and without “real time preview”.

My old desktop PC which I haven’t edited music on for years therefore don’t update anymore (but I’ll only have time to be at this afternoon) still has Audacity 2.0.3 !
The last bunch of years I’ve done all my editing on laptop which I keep up to date!

Can you please tell me what I need to do to be able to use that mid-side plugin on the fly?

The voxengo plugins are VST effect plugins, they only work in Audacity on Windows & Mac.

It’s a rigmarole getting them installed in Audacity, e.g. see …
https ://

Once you download & install them they appear on the Audacity effects list,
(after they are enabled in Audacity’s plugin manager)

The voxengo plugin download includes multiple formats,
but currently only the 32-bit VST (Not VST3) versions works in Audacity on Windows.