I’ve been struggling with a very slight echo problem for a couple weeks…
Started all of a sudden about 3 weeks ago…
Checked all my connections and thought I figured it out…but no joy…
My setup…
A
udacity 2.3.2
Win 10 Pro 21H2
Pioneer PL630
Denon DL110
Cambridge Duo preamp
SVGA NU audio card
I digitize vinyl…reel to reel and cassette into my computer and make CD’s…make MP3’s etc…
I have uploaded 2 PNG files…
“Normal” shows an audio file in Audacity and I consider this normal…
“Flat top” shows an audio file in Audacity and this file seems to have the distortion…
These 2 recordings were made about a week apart…
IF I just run the vinyl thru the computer WITHOUT recording it in Audacity there is NO distortion at all…
There is no distortion if I record from a reel to reel or from cassette…
It seems to occur only with vinyl…
I can describe this distortion as a slight echo…hear it only on the louder notes…
So I thought the Cambridge Duo preamp…so I tried a different preamp…no difference…
Not the preamp…
Since my TT needed a tune up…took it to the shop and asked them if they could hear any distortion…nope…
Then I noticed the difference between the two files…one looks normal and the other looks like it’s been compressed…
I am thinking some setting in Audacity is compressing and adding the distortion…and I cannot figure out what it is…
And you can hear the distortion both when recording and after…
Appreciate any thoughts / suggestions or if you have any tests I can do…please advise…
Many thanks for your time
Steve
NOTE: not sure I got the files uploaded correctly…there is a “Place Inline” button next to the .PNG files and didn’t know what to do with it…
Both of these images show that there is clipping due to excessive input levels somewhere in your recording chain. The second one happens to clip at +/- 0.5 db as audacity sees it which shows that its not audacity’s audio input which is causing it. Clipping can occur anywhere in the input chain so you should start with the cartridge and pre-amp settings. Have you inadvertently set the pre-amp phono input to the wrong impedance ( cartridge type setting ) for example by using a moving coil setting for a moving magnet cartridge. If this is correct then work through the input chain and make sure that amplifier ( or pre-amp ) volume settings do not make any difference to the waveform and input levels. If non of this applies another possibility is that you have somehow got two input sources recording simultaneously so try setting the listening or monitoring level right down while you are recording. Remember that a loudspeaker which is close to the deck can feed back through the cartridge if the volume is high. At proper signal levels you should never see what you call flat-top waveforms.
So… If you plug-in something else into the soundcard, you can go over -6dB (50%)? That would indicate a problem with your preamp. I assume there’s no other analog electronics in the recording chain?
On the computer-side, something similar to this can happen if you Windows is configured for mono so check that, and unplug the left & right connections one at a time to make sure you’re getting both channels, and that they are properly separated.
…It doesn’t look like you’ve got this exact-situation, but when you record in mono from a stereo soundcard/interface the signals are cut in half to prevent clipping when the signals are combined. That means either channel alone will clip at -6dB, and if you’re only using one input you’ll see clipping at -6dB.
I can describe this distortion as a slight echo…hear it only on the louder notes…
If it sounds OK when you lower the volume (and if you are getting stereo) that could be a solution (or a “work around”). [u]Clipping[/u] is BAD but low-digital levels are not. You can amplify or normalize after recording.
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Your “good recording” also appears to be clipping. Leave some headroom! We generally recommend shooting-for -6 to -3dB but nothing bad happens if you accidently get close to 0dB or if you record a lot lower. (Pros generally record around -12 to -18dB, at 24-bits.)
With analog tape you need a hot signal to overcome tape noise (hiss). But with digital… no tape noise and low levels are not a problem. Again, you can boost/normalize after recording. Also, analog tape is more forgiving if you go over 0dB. Your analog-to-digital converter is hard-limited to 0dB and it will hard-clip if you try to go over. Analog tape can go over 0dB where it starts to soft-clip and the tape record/playback equalization further “smooths” any clipping.
