Hi, Chris,

John has provided a good answer, but I wonder where the delay came from.

If the azimuth is way off, summing the channels can cause mush while an 
individual channel will be passable, but not great. Delaying one channel 
is actually how the "azimuth correction" tools work. They only adjust 
azimuth based on delay. The slope of the notches is too steep to 
reliably recover much by using EQ without adding noise.

Also, if it were recorded on an 8-track cassette machine like a TASCAM 
238, that has staggered heads, but I don't know how those would align 
with a stereo head. You can see the drawing here:
http://www.richardhess.com/tape/cass_trk_lrg.gif

Also, if these are stereo recordings, if the mics were not coincident, 
then there will be delays between the channels which can result in mush 
when summed,  but that will be different for each discrete sound source 
in the recording.

Cheers,

Richard

On 2020-10-21 10:21 a.m., Chris Brady wrote:
> John - great - thank you. I'll try all of this. I don't think that its
> print through because the issue is consistent. Chris B.
> 
> On 21/10/2020, John Gledhill <[log in to unmask]> wrote:
>> Forgot to add - insert the measure delay into the start of the preceding
>> channel
>>
>>
>>
>> I doubt it is a micro second -
>> If the delay is constant here is what you can do
>> Split the stereo track to mono
>> use "analyze ->splot spectrum-and use the autocorrelation
>> get rid of the grid
>> if the delay is constant you should see a sharp peak
>> export the date and you can zero in on the delay with the largest peak -
>> artificially 0.1 second in the sample I sent.
>> If the delay is not constant the peak will be smeared so pic the
>> midpoint or throw one channel away or save it separately if it is
>> smeared over too wide a time distribution
>>
>> On 10/21/2020 8:34 AM, Chris Brady wrote:
>>> We are digitising some cassette tapes using Audacity.. A batch of them
>>> are stereo, however they have exaggerated separation of the channels
>>> (perhaps they need normalisation?), and one channel is a microsecond
>>> behind the other. We don't actually need stereo, amd have tried to
>>> merge the channels into mono. But this sounds dreadful - the speech
>>> part sounds OK, but the music is very 'echo-ie).
>>>
>>> Another batch have delays from one channel to the other measuring in
>>> seconds. How can we time-shift one channel to match the other one?
>>>
>>> Thanks - Chris B.
>>>
>>>
>>
>> --
>> John Gledhill
>> BIT WORKS Inc.
>> 905 881 2733
>> [log in to unmask]
>> www.bitworks.org
>>
>>
>>
> 
> 

-- 
Richard L. Hess                   email: [log in to unmask]
Aurora, Ontario, Canada                             647 479 2800
http://www.richardhess.com/tape/contact.htm
Track Format - Speed - Equalization - Azimuth - Noise Reduction
Quality tape transfers -- even from hard-to-play tapes.