Mono pre-amp individually bounce Left and Right to create Stereo - thoughts?

[canidoit]

Most of my preamps are mono and I am delving into analogue summing by way of feeding stereo sub stems into my outboard and then digitally summing the bounced results.
I was considering buying a stereo Neve clone (Warm Audio WA-273 or 273-EQ) for this purpose but having second thoughts as I am only doing this for experimentation and I do have one mono Neve clone pre-amp.

Would I get the-same results if I were to bounce Left and Right separately into the mono pre-amp and then mix it in stereo, than if I were to feed it into a stereo pre-amp?
Example
Drums Left > mono preamp ] played back in DAW with other Right bounce
Drums Right > mono preamp ] played back in DAW with other Left bounce
vs
Drums Left/Right > stereo preamp

Or is there more to the Neve clone stereo pre-amp than just two independent mono preamps together to form stereo?

What sort of issues would arise from the mono method above - ie. phasing, coloration mismatch or if the-same as stereo pre-amp?

Thank you.

 

[scott2000]

Probably be worried about some phasing issues but who knows . Growing weary of the process may be the worst to come of it.

 

[Ricardus]

You might be able to align them closely, but it wouldn't be sample accurate.

 

[canidoit]

So the issue is most likely bouncing separate Left and Right channels not at the-same time causing possible mis-alignment between left and right on the bounced audio when playing it back.

Is there a certain amount of samples misalignment acceptable/noticeable before it starts affecting a stereo file?

I do notice that people do track in stereo using separate mono pre-amps at the-same time, isn't the two bounced mono audio still have possible issues of misalignment?

 

[scott2000]

Is there a certain amount of samples misalignment acceptable/noticeable before it starts affecting a stereo file?

Of course there is. Some probably even use it for effect on certain material.

I do notice that people do track in stereo using separate mono pre-amps at the-same time, isn't the two bounced mono audio still have possible issues of misalignment?

They're being recorded and placed "at the same time" so, it's not exactly the same thing. Unlikely there will be any major issues doing it the way you propose unless your gear or external environment is quirky from one instance to the other . Sounds like a change in sound is the goal to some degree anyhow. Analog TMT (Tolerance Modeling Technology)

 

[canidoit]

I just used the single channel NV73(neve clone) to bounce the left and right separately and played the Left and Right files back in Logic and the results were amazing!

The stereo image just got so much wider and the separation more distinguishable. Its like the instruments have been moved further apart to create its own space in the stereo field.

On the headphones, it went from only covering 120 degrees, to full 180 degrees with hard left and right sounds feeling like it is at the side of my ears, unlike before, it felt like it was slightly forward towards the inside.

What is causing this? Is it the pre-amp or possibly the mismatch between the timing of left and right audio, or harmonics not being the-same when bouncing it not at the-same time?

The stereo image seems the-same but just stretched wider and around my head on the headphones. I have not gotten the-same results bouncing stereo using a compressor such as the API2500 or Serpent bus compressor.

 

[TwentyTrees]

What is causing this? Is it the pre-amp or possibly the mismatch between the timing of left and right audio, or harmonics not being the-same when bouncing it not at the-same time?

Interesting result! You could control for the effect of the preamp with a loopback test (sending your left and right channels out one at a time, with DAC patched to ADC), and comparing the results. It might also be illuminating to see what a correlation meter has to say.

How does your preamp-treated mix sound through speakers? Are you losing any solidity in the low end?

 

[canidoit]

Interesting result! You could control for the effect of the preamp with a loopback test (sending your left and right channels out one at a time, with DAC patched to ADC), and comparing the results. It might also be illuminating to see what a correlation meter has to say.

How does your preamp-treated mix sound through speakers? Are you losing any solidity in the low end?

Hi TwentyTrees,

I found the same results through the speakers and found the low mid to low end beefier.

I just did further tests bouncing the stereo out with two individual API 512s at the-same time and the Neve clones seems to produce a wider stereo image. The Api is wider compared to without a pre-amp, but not as wide as the NV73 separate Left and Right bounce.

It might be possible that if I bounce Left and Right one at a time on the API, I might get the same width as the NV73? I will likely test this out in the future.

This sort of makes me question if a summing box is truly necessary as I did a test once, doing 4 stereo stems into the API 2500 and mixed it all to stereo in the box and the build up of the low end was substantial and I was not getting the width and separation I am getting now with the NV73. I also tried this test with the SB4000 with similar results. Both still made the mix wider though than if I did not use the outboard and just bounced straight in the box.