Archiving mono records...

[doctorcilantro]

My preamp has a mono switch, but I am embarking on a project that would mean not using this particular pre. If I create a mono recording project on my PC, would this be the same as using a mono cartridge or a mono switch a pre?

thanks

dc

[Don Richard]

I'm not sure that switching your preamp to mono will result in a mono recording if you are using the preamp's tape out jacks. Most preamps with a mono/stereo switch sum the L & R after the tape outs. What ou could do is to tee off of the main L & R outputs and then go into the PC , but be aware that the volume and tone controls will then affect the recording.

[Mallette]

Hmmm.... Don may well be right, but that has not been my experience. On all the preamps I've used, the VU meters jump right into sync when the mono button is pushed.

From what he says, you mileage may vary. Put something with VU meters (real or virtual) on the tape out and see.

Dave

[doctorcilantro]

Okay, I'll check with the PC or my Tascam tonight.

Would creating a mono recording (in PC wave editor) of a mono record be essentialy identical to flipping a hardware mono switch; I assume it is the more I think about it.

DC

[Mallette]

Okay, I'll check with the PC or my Tascam tonight.

Would creating a mono recording (in PC wave editor) of a mono record be essentialy identical to flipping a hardware mono switch; I assume it is the more I think about it.

DC

The answer is yes and no. Yes, it is essentially the same for a digital file, but if you are coming from a TT you want to sum the channels ASAP as you'll get lower noise from summing the stereo signal. Actually, if you do a lot of it, it's best to make a switch between the TT and the phono inputs of the preamp that will sum the signal in all possible ways, i. e. L-R , R-L, L+R, L, R, etc. as one will always provide a noticably lower noise than the others. This is especially true if you encounter very old "hill and dale" recordings.

Dave

[doctorcilantro]

L + R contain the same information a mono record groove?

Could I just capture one channel digitally, and record as mono file as well.

DC

[Mallette]

>L + R contain the same information a mono record groove?

Yes. To effectively capture this with a stereo stylus you need to sum the output electrically. Depending upon the disc, one of the various methods I mentioned in a previous post may yield lower noise. However, simply summing the L+R will help a lot. Mono LP's are pretty much all the same and L+R is usually optimum. Mileage varies more with older 78's where various cutting schemes may have been applied. When you get VERY old, you start running into "hill and dale" cutting.

Dave

[Edgar]

I recommend that you record in stereo, if possible. There are emerging DSP restoration methods that compare the two supposedly identical channels and use differences between them as the basis for noise reduction. Even if you don't use one of those methods right now, you'll still have the original two channels available if you decide to in the future. In the mean time, you can sum the recorded channels during playback on your PC and get the same results as if you had used a mono cartridge or a mono switch on your preamp.

Greg

[doctorcilantro]

Some of the 78 archiving discussion on the DCart 7 forums talks about recording stere, using restoration tools, and converting to mono last. Some good tools in that app.

DC

[Mallette]

I recommend that you record in stereo, if possible. There are emerging DSP restoration methods that compare the two supposedly identical channels and use differences between them as the basis for noise reduction. Even if you don't use one of those methods right now, you'll still have the original two channels available if you decide to in the future. In the mean time, you can sum the recorded channels during playback on your PC and get the same results as if you had used a mono cartridge or a mono switch on your preamp.

Greg

I've thought about this for a while. I am generally a "play it where it lies and process later" type in that once done you can't undo, but you can always redo. However, I disagree here. Mono was not meant to be played with a stereo pickup so it makes no sense to take the extra noise that comes with stereo recording and process it out later. Just don't record it in the first place.

Dave

[Edgar]

Mono was not meant to be played with a stereo pickup so it makes no sense to take the extra noise that comes with stereo recording and process it out later.  Just don't record it in the first place.

With signal processing there is so much more that can be done to remove noise than just L+R or L-R, particularly if one has multiple copies of the same signal. And with modern digital signal processors getting more powerful in every generation, things can now be done in real time that were unimaginable not very long ago.

Greg

[Mallette]

You miss my point. I am fully conversant with digital processing. However, you are talking about removing noise that you have created by playing the discs incorrectly in the first place.

My 78 TT is set up with a switch in the phono cable before the preamp that allows me to select all variants of sum a difference from the stereo pickup. Most of the time L+R does the job nicely. Sometime other settings are better. In all cases I just rather listen to it correctly than have to post process.

Dave

[Edgar]

You miss my point.  I am fully conversant with digital processing.  However, you are talking about removing noise that you have created by playing the discs incorrectly in the first place.

The noise is there on the disk regardless of how it's played. By summing to mono, you are cancelling common-mode noise and increasing differential-mode noise. Of course, the way that mono records were cut causes noise to be predominantly common-mode. But with processing, worst-case noise reduction is at least as good as best case with sum/difference (because sum/difference is still an option with post-processing), so it makes sense to me to record both channels. You are, of course, free to do what works best for you.

Greg

[Mallette]

You miss my point. I am fully conversant with digital processing. However, you are talking about removing noise that you have created by playing the discs incorrectly in the first place.

The noise is there on the disk regardless of how it's played. By summing to mono, you are cancelling common-mode noise and increasing differential-mode noise. Of course, the way that mono records were cut causes noise to be predominantly common-mode. But with processing, worst-case noise reduction is at least as good as best case with sum/difference (because sum/difference is still an option with post-processing), so it makes sense to me to record both channels. You are, of course, free to do what works best for you.

Greg

Thank you, sir. My ears tell me that pre-summing works well, and since much of my play of mono records is "live," that's the best for me. Even recording I want to keep digital processing to a minimum so I'd prefer to have as little as possible in the virgin tracks before exposing it to process. That process which processes least processes best is my motto.

Dave