Old 02-16-2020, 02:08 PM   #1
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Default outboard Mono w/stereo

I have a buddy who wants me to run his mix through my Pultec. problem is, I only have 1 pultec now. He doesn't want any eq or anything on it. He just wants me to print it with the sound straight through.

If I send a mix through mono and convert it back to stereo, will that work? Or should I tell him no?
He will give me 100 bucks to print 10 songs through it. So if it is possible, I could use the cash
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Old 02-16-2020, 02:25 PM   #2
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If I send a mix through mono and convert it back to stereo, will that work? Or should I tell him no?
He will give me 100 bucks to print 10 songs through it. So if it is possible, I could use the cash
What do you mean? If you run a stereo mix through a mono unit, how will you convert it to stereo?
If you want to run a stereo mix through a single mono unit you could do two passes, one for left & one for right, but you'd have to be very careful when re-assembling, so that they are aligned exactly.
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Old 02-16-2020, 02:50 PM   #3
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That won't be possible, even if you splít the audio in Left and right on separate tracks , if you print left and then right you´ll have hard time with phase relations, since its a hardware unit and it responds different every time . So, short answer, don't do it.
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Old 02-16-2020, 02:58 PM   #4
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NO you can’t go stereo>mono>stereo

YES you can go left>pultec>left and then the right side each to separate tracks. It will be exactly the same (really closer) to running through a “stereo” EQ that is actually dual-mono.

As long as you change nothing except channel assignments between passes it should line up exactly and just work fine. It’ll take twice as long, but...
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Old 02-16-2020, 03:05 PM   #5
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Thanks so much guys. this is really good info. It sounds like it is a horrible pain to do. And he wants 10 songs done. Do you guys think it is worth it to print left and then the right. All for a bill?

Should I just tell him no? Or tell him it needs to be more money? From what you guys said, it sounds like a big pain and a lot of time.
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Old 02-16-2020, 04:10 PM   #6
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Zoop zoop done. Charge at least 2.5 times the length of all 10 songs together.
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Old 02-16-2020, 04:32 PM   #7
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Originally Posted by ashcat_lt View Post
NO you can’t go stereo>mono>stereo

YES you can go left>pultec>left and then the right side each to separate tracks. It will be exactly the same (really closer) to running through a “stereo” EQ that is actually dual-mono.

As long as you change nothing except channel assignments between passes it should line up exactly and just work fine. It’ll take twice as long, but...
Its is possible to do for sure, Phase coherence gets compromised i´m afraid. Stereo and dual mono hardware units are made to avoid this problems electronically.
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Old 02-16-2020, 07:39 PM   #8
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Its is possible to do for sure, Phase coherence gets compromised i´m afraid. Stereo and dual mono hardware units are made to avoid this problems electronically.
They can't be. It's two separate circuits which just can't be as close to the same in any given variable than just one. Believe in fairies if you want, but...
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Old 02-16-2020, 09:19 PM   #9
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Thanks so much guys. this is really good info. It sounds like it is a horrible pain to do.
It's not, though. Just send left and right through the Pultec separately and record back into Reaper. Change the routing within Reaper. Don't unplug anything after it's connected.

Variations between separate analog channels is going to be much greater than variations within a single channel moment to moment. What you'll do is actually more consistent. Do some tests with a mono signal and see if the phase correlation is off.
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Old 02-17-2020, 04:20 AM   #10
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Originally Posted by ashcat_lt View Post
They can't be. It's two separate circuits which just can't be as close to the same in any given variable than just one. Believe in fairies if you want, but...
I encourage you to do some tests, like i did before.

STEPS>

-Create a track, import stereo content (drums,final mix, etc)
-unroute that track from master
-send left channel of that track to left channel of the outboard unit
-print the result
-do the same for the right channel
-finally print a stereo version .
-open pan wide (match pan law before) for left and right printed version
-flip polarity of ths stereo print

-Check if they cancel...they wont..
-Is not the same.
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Old 02-17-2020, 04:45 AM   #11
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Originally Posted by pepe44 View Post
I encourage you to do some tests, like i did before.

STEPS>

-Create a track, import stereo content (drums,final mix, etc)
-unroute that track from master
-send left channel of that track to left channel of the outboard unit
-print the result
-do the same for the right channel
-finally print a stereo version .
-open pan wide (match pan law before) for left and right printed version
-flip polarity of ths stereo print

-Check if they cancel...they wont..
-Is not the same.
What is this supposed to prove? The whole point of a stereo file is that there are differences between left & right channels, so of course they won't null?
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Old 02-17-2020, 04:54 AM   #12
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Quote:
Originally Posted by pepe44 View Post
I encourage you to do some tests, like i did before.

STEPS>

-Create a track, import stereo content (drums,final mix, etc)
-unroute that track from master
-send left channel of that track to left channel of the outboard unit
-print the result
-do the same for the right channel
-finally print a stereo version .
-open pan wide (match pan law before) for left and right printed version
-flip polarity of ths stereo print

-Check if they cancel...they wont..
-Is not the same.
If the original track is actual stereo material you don't want them to be the same do you?
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Old 02-17-2020, 05:19 AM   #13
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Originally Posted by domzy View Post
What is this supposed to prove? The whole point of a stereo file is that there are differences between left & right channels, so of course they won't null?
The point here is that if you split a stereo track into Left channel and Right channel , print those in two passes at different times they wont be the same has if you do a stereo track in a stereo unit at the same time. Has i said above, hardware manufacturers deal with this using internal sidechain for left and right channel, mainly compressor units.
In the case of an EQ like the pultech, we all know (or should know) that eq introduces phase rotations as soon you boost or cut. If you do two passes , phase should be the same but! we´re talking about a tube eq that responds to signal depending on the program it is "listening". There are small variations, maybe you wont listen or maybe you will.
Im not here to argue or to sound rude, no! I did all those tests , i´ve been on that same place, my end results told me i should avoid that method, it compromised my final work and i didnt like it!
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Old 02-17-2020, 05:21 AM   #14
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There are some other methods that i think work best in this case. creating an impulse of the eq is one of them, you should try it.
I use Waves Q-clone for this.
Or using the M/S technique!
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Old 02-17-2020, 05:37 AM   #15
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Originally Posted by pepe44 View Post
The point here is that if you split a stereo track into Left channel and Right channel , print those in two passes at different times they wont be the same has if you do a stereo track in a stereo unit at the same time. Has i said above, hardware manufacturers deal with this using internal sidechain for left and right channel, mainly compressor units.
In the case of an EQ like the pultech, we all know (or should know) that eq introduces phase rotations as soon you boost or cut. If you do two passes , phase should be the same but! we´re talking about a tube eq that responds to signal depending on the program it is "listening". There are small variations, maybe you wont listen or maybe you will.
Im not here to argue or to sound rude, no! I did all those tests , i´ve been on that same place, my end results told me i should avoid that method, it compromised my final work and i didnt like it!
No. Unless there is something wrong with the unit, or with the methodology, the differences between channels will be larger than running the same audio through the same channel several times. End of story.
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Old 02-17-2020, 05:54 AM   #16
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The point here is that if you split a stereo track into Left channel and Right channel , print those in two passes at different times they wont be the same has if you do a stereo track in a stereo unit at the same time.
Yes they will be. Unless the unit is faulty. Poorly maintained and designed tube equipment will sometimes have very bad tolerances, varying the frequency (and thus phase) response with heat, etc. One is no better than the other, or rather, if you use equipment with this behaviour, it won't matter if you sum mono-transfers or print directly to stereo, each pass will be unlikely to null with other passes anyway.
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Old 02-17-2020, 06:00 AM   #17
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Im not here to argue or to sound rude,
that's fine, but on a public forum you should expect to get argument if you assert stuff as true when it's not
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Old 02-17-2020, 06:48 AM   #18
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I tested again, using an external eq, elysia xfilter 500.
I setup Reaper this way:
Stereo track, item properties, Channel properties, Mono L THEN print passing on the Eq (left channel) on a new track the Left channel.
Same for the right channel(using outboard left channel again). I did a print of a stereo version too ( this is a stereo EQ).
I time aligned the stereo version and the one combined Left and Right prints on a reaper "Bus track".
IF they were exactly the same (time aligned / amplitude match) they would cancel completely when flipping 180´ohe over the other right ? They dont. i get full signal at max level of -40 dBFS. This shows there are differences.
I´m not saying IT DOESNT WORK, IT DOES. BUT...is not the same.
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Old 02-17-2020, 07:01 AM   #19
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Just a final thought , this one goes for the original post. We do this for decades, dont mind with my responses. the changes are minimal and you wont be able to even listen to them. With that said i was just trying to explain that there could be some phase problems at the end. IF you´re happy with the result, fine! go for it.
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Old 02-17-2020, 08:13 AM   #20
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Pepe, what are you trying to null exactly? It's not clear to me. The source should be mono, sent through the same analog channel twice. I'm curious how much they will null. Noise will be different, of course.

You do have a point about compressors, though. There might be some stereo-linking / gain interaction between channels.
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Old 02-17-2020, 08:39 AM   #21
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Pepe, what are you trying to null exactly? It's not clear to me. The source should be mono, sent through the same analog channel twice. I'm curious how much they will null. Noise will be different, of course.

You do have a point about compressors, though. There might be some stereo-linking / gain interaction between channels.
Nulling the stereo print passing on the external Eq with the two printed version of the Left / Right.
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Old 02-17-2020, 10:13 AM   #22
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Honestly...

Folding stereo down to mono is a pretty big move. I hope someone would notice that and scream! You could do it 1 channel at a time as mentioned. You could also simulate a little analog line amp stage generation loss about 7 different ways. Roll off some highs and/or saturate/distort just a little. You and I know the client would never know in a million years but...

I might run two passes and just do it. Probably be inclined to dial up a ReaEQ low pass and some JS saturation plugin and simulate the loss. Then be a smart ass and show the client "Yep, sounds just like doing this!" as an aside.
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Old 02-17-2020, 10:29 AM   #23
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Originally Posted by pepe44 View Post
I tested again, using an external eq, elysia xfilter 500.
I setup Reaper this way:
Stereo track, item properties, Channel properties, Mono L THEN print passing on the Eq (left channel) on a new track the Left channel.
Same for the right channel(using outboard left channel again). I did a print of a stereo version too ( this is a stereo EQ).
I time aligned the stereo version and the one combined Left and Right prints on a reaper "Bus track".
IF they were exactly the same (time aligned / amplitude match) they would cancel completely when flipping 180´ohe over the other right ? They dont. i get full signal at max level of -40 dBFS. This shows there are differences.
I´m not saying IT DOESNT WORK, IT DOES. BUT...is not the same.
So, you're saying you're getting -40 dBFS difference instead of a straight null? Across both channels, even the left channel? That doesn't make any sense. How are you "lining up" the tracks exactly and why? Why not just record them in place, on a separate track, next to the original mix? THen you would not have to line anything up, as long as you keep the same settings (round trip latency, etc).
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Old 02-17-2020, 10:32 AM   #24
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Just a final thought , this one goes for the original post. We do this for decades, dont mind with my responses. the changes are minimal and you wont be able to even listen to them. With that said i was just trying to explain that there could be some phase problems at the end. IF you´re happy with the result, fine! go for it.
There are no phase problems, if you have the correct methodology and working equipment.
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Old 02-17-2020, 11:13 AM   #25
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This is the null test:



Sorry to push the issue, but I'm curious.
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Old 02-17-2020, 11:28 AM   #26
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You can get “stereo linked” gain out of a mono compressor if it has a key/sidechain input. Different compressors do that differently, so you’d want to think about it. In most cases, just sending the summed stereo signal on each L/R pass would work fine.
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Old 02-17-2020, 11:52 AM   #27
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When I say I time aligned the stereo version, I mean the stereo version of the audio I sent to the external eq.
Só basically I ran 3 passes to the eq.
1 - left channel of the drum loop
2 - right channel of the drum loop
3- stereo drum loop into the stereo eq.
I time aligned all versions against the original drum loop, non processed audio track, only for testing purposes. Doesn't matter for the main topic.

The routing is simple. I explained couple posts ago.

Track 1 - stereo drum loop.
Go to preferences and make into Mono left and send to outboard, print that on a new track.
Go back to preferences of the stereo drum loop again and change mono left to mono right, print the result.l on a new track, Hard pan left print, hard pan right print.
Go back to preferences of the drum loop and change mono right back to stereo, so it goes back to the initial setting. Send that to the eq ( I only did this because the external eq I am using for this tests is a stereo unit).
Print the result.
Now you have 3 tracks.
Left print
Right print
Stereo print

Now.. The null test purpose is to check the stereo print against the left+right version( 2passes)
Shouldn't they cancel?
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Old 02-17-2020, 10:38 PM   #28
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Now.. The null test purpose is to check the stereo print against the left+right version( 2passes)
Shouldn't they cancel?
Using this method, no. Not perfectly. Left channel should cancel except for residual noise, and right channel should cancel except for r/l channel variance and residual noise.

The thing is, there should be NO difference quality wise, in regards to the OP. A channel is a channel. It makes no difference, quality wise, if you sum 2 mono passes to 1 stereo file or if you print 1 stereo file right away. There is no magic happening in stereo outboard units that doesn't happen in mono units. It's two different channels, with slightly different characteristics, that's all.

You would get the same discrepancy you're complaining about just comparing the left and right channel of your stereo outboard (sending the same mono track to both naturally). Individual analog channels have tolerances, small, but probably measurable.

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Old 02-17-2020, 10:43 PM   #29
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I time aligned all versions against the original drum loop, non processed audio track, only for testing purposes. Doesn't matter for the main topic.
Well, it might. How exactly did you "time align" the tracks?
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Old 02-18-2020, 02:09 AM   #30
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Well, it might. How exactly did you "time align" the tracks?
Measuring in samples, nudging in samples.
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Old 02-18-2020, 09:27 AM   #31
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I have a buddy who wants me to run his mix through my Pultec. problem is, I only have 1 pultec now. He doesn't want any eq or anything on it. He just wants me to print it with the sound straight through.

If I send a mix through mono and convert it back to stereo, will that work? Or should I tell him no?
He will give me 100 bucks to print 10 songs through it. So if it is possible, I could use the cash
I'd set it up as Mid-Side and use regions and action markers to automate running the songs through. Once for mids and once for sides.
Doesn't make sense not to use the filters in the Pultec but if that's what he wants…
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