Old 04-08-2011, 11:39 AM   #1
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Default Crosstalk...

Just curious, where does stereo crosstalk come into play on a hardware mixer/console?

Am I correct in my thinking that it only happens on the 2-buss (or any multi-channel buss) pre-everything?

Thanks.

Last edited by d.bop; 04-08-2011 at 11:41 AM. Reason: the usual...
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Old 04-09-2011, 11:49 PM   #2
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Hi there, crosstalk is "bleed through" from 1 audio circuit to another, in mixers this will relate to all channels including busses and master bus. This can happen for a number electronic reasons. Sometimes circuits in a badly designed mixer interact. This can come from common power supplies and also bad physical circuit layout.

It happens on a channel by channel basis at generally a very low level in well designed equipment.

It is arguably one of the reasons why analogue summing sounds different and also a characteristic of analogue audio electroncis itself.

cheers

(PS good and interesting question!)
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Old 04-10-2011, 11:07 AM   #3
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Originally Posted by SafeandSound View Post
Hi there, crosstalk is "bleed through" from 1 audio circuit to another, in mixers this will relate to all channels including busses and master bus. This can happen for a number electronic reasons. Sometimes circuits in a badly designed mixer interact. This can come from common power supplies and also bad
physical circuit layout.

It happens on a channel by channel basis at generally a very low level in well designs equipment.

It is arguably one of the reasons why analogue summing sounds different and also a charcateristic of analogue audio electroncis itself.

cheers

(PS good and interesting question!)
Thanks! I'm thinking of getting into DSP and thought this would be something fun to try and emulate with JS programming. Just needed a little better understanding

Do you know any typical crosstalk levels in higher end (and lower end) consoles? Unfortunately I don't have access to any boards to do any testing..
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Old 04-10-2011, 11:29 AM   #4
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Originally Posted by d.bop View Post
Thanks! I'm thinking of getting into DSP and thought this would be something fun to try and emulate with JS programming. Just needed a little better understanding

Do you know any typical crosstalk levels in higher end (and lower end) consoles? Unfortunately I don't have access to any boards to do any testing..
Crosstalk level is usually one of the specs posted by gear manufacturers. pull up specs of gear that you are interested in and you should see it
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Old 04-10-2011, 11:35 AM   #5
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No disrespect meant here d.bop but this topic has put a little grin on my face

I've worked for years designing and building analog audio gear and one of the things I do my utmost to design OUT of the gear is crosstalk. Now I read of you writing software code to incorporate crosstalk INTO your emulations

Don't get me wrong, I reckon what you are doing is a cool thing and I'm all for good software emulations. I just found the irony as a hardware designer amusing.
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Old 04-10-2011, 11:35 AM   #6
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Crosstalk level is usually one of the specs posted by gear manufacturers. pull up specs of gear that you are interested in and you should see it
Very nice. Thanks!
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Old 04-10-2011, 11:37 AM   #7
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To be more help to your question, crosstalk generally increases with frequency. It is relatively easy to avoid it in the midrange but things are very different at 10KHz compared to 1KHz. That is one of the reasons many manufacturers quote crosstalk figures at 1KHz. It makes their product seem higher spec'd to an unassuming person.
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Old 04-10-2011, 12:33 PM   #8
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No disrespect meant here d.bop but this topic has put a little grin on my face

I've worked for years designing and building analog audio gear and one of the things I do my utmost to design OUT of the gear is crosstalk. Now I read of you writing software code to incorporate crosstalk INTO your emulations

Don't get me wrong, I reckon what you are doing is a cool thing and I'm all for good software emulations. I just found the irony as a hardware designer amusing.
Heh it's just an experiment I agree though! It is funny. Now that we have super clean digital, the new trend is to dirty it up a bit.

I modded liteon's nonlinear JS plugin not too long ago to work kind of like Steven Slate's VCC (master/slave setup.) I thought this might be neat to throw in there. We'll see though, I haven't coded in FOREVER and I'm not really that big of a math wiz.
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Old 04-10-2011, 12:35 PM   #9
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To be more help to your question, crosstalk generally increases with frequency. It is relatively easy to avoid it in the midrange but things are very different at 10KHz compared to 1KHz. That is one of the reasons many manufacturers quote crosstalk figures at 1KHz. It makes their product seem higher spec'd to an unassuming person.
So if I were to try and do this, it sounds like I'd have to program some sort of slope, right?
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Old 04-10-2011, 12:49 PM   #10
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So if I were to try and do this, it sounds like I'd have to program some sort of slope, right?
Yep. It is pretty much a universal thing in analog audio that as frequency increases, so does crosstalk.
There are some exceptions where crosstalk can be lowest in the midrange and have a small rise in the low end and a large rise in the top end. Phono preamps tend to do this because of their RIAA equalisation response.

Here's a couple of typical crosstalk graphs I found via Google images...



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Old 04-10-2011, 01:11 PM   #11
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Is the increase in crosstalk versus frequency related to the conversion of electrical current into an EM field via inductance? (bit like what a coil does?)

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Old 04-10-2011, 01:20 PM   #12
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Is the increase in crosstalk versus frequency related to the conversion of electrical current into an EM field via inductance? (bit like what a coil does?)

More or less, yeah. Higher frequencies are shorter in wavelength and can be 'transmitted' more easily through shorter 'antennas'. PCB tracks and buss connectors make very effective antennas which is why good designs incorporate ground planes on the PCB's and earth wires interleaved between signal wires in buss connectors in order to reduce the 'transmission' (AKA crosstalk).
Two other common means of lowering crosstalk are to use low impedance circuitry (which also uses more power) and/or to run the power supplies at higher voltages. This also has the advantage of increasing headroom, decreasing noise and improving frequency and phase response. It is also significantly costlier to implement which is why decent consoles cost more.
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Old 04-10-2011, 01:52 PM   #13
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Thanks for that info

of course, being the curious one I am that answer leads to a lot more questions but I won't take up your time, will just have to finish reading about it myself at some point!
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Old 04-10-2011, 02:03 PM   #14
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It's a long journey and there's always more to learn. Asking questions and being curious is what got me started 30 years ago. I am still asking questions. They have just become more complex questions!!!
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Old 04-10-2011, 02:14 PM   #15
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Quote:
Originally Posted by Dannii View Post
More or less, yeah. Higher frequencies are shorter in wavelength and can be 'transmitted' more easily through shorter 'antennas'. PCB tracks and buss connectors make very effective antennas which is why good designs incorporate ground planes on the PCB's and earth wires interleaved between signal wires in buss connectors in order to reduce the 'transmission' (AKA crosstalk).
Two other common means of lowering crosstalk are to use low impedance circuitry (which also uses more power) and/or to run the power supplies at higher voltages. This also has the advantage of increasing headroom, decreasing noise and improving frequency and phase response. It is also significantly costlier to implement which is why decent consoles cost more.
I'm not sooo deep in electronics, can the reason for crosstalk in an audio circuit like a mixer be found more on the inductive or more on the capacitive side of the fence?
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Old 04-10-2011, 02:24 PM   #16
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It tends to be a mixture of both and varies according to design. It also varies according to the particular signal stage too. A preamp with transformer balanced inputs is going to be subject to inductive effects at the inputs but may be subject to capacitive effects on the PCB and signal wiring. In reality, it is always a mixture of both which leads to resonances and signal coloring. It is often the layout of the circuit rather than the actual circuit design itself that leads to coloration and this coloration is sometimes desirable, especially in esoteric and mysterious vintage gear.
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Old 04-10-2011, 02:30 PM   #17
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Ah ok, i see.
Thank you for the information.
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Old 04-10-2011, 02:35 PM   #18
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You're welcome
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Old 04-11-2011, 08:14 AM   #19
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Thank you for all of the information! I can tell I'll be learning A LOT while I'm working on this. I already have a couple of ideas for implementing crosstalk in JS, but I need to reabuild my "advanced" math skills first

Exciting!
Thanks again. Feel free to continue the discussion!
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Old 04-11-2011, 10:55 AM   #20
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Thanks Dannii for giving further details ; )
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Old 04-14-2011, 08:04 PM   #21
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Looking forward to "hear" this crosstalk plug, if it ever come out!

I think a great ideia is to add some kind of crosstalk btw nearby channels/tracks AND add some kind of dynamic "drive" on those tracks.
Do you know what I mean?
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Old 04-14-2011, 09:09 PM   #22
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Looking forward to "hear" this crosstalk plug, if it ever come out!

I think a great ideia is to add some kind of crosstalk btw nearby channels/tracks AND add some kind of dynamic "drive" on those tracks.
Do you know what I mean?
Thanks! I got the basic crosstalk stuff going, I just need to match the frequency response to something similar to the graphs dannii posted earlier. It might take a while, I'm still new at this DSP stuff

It's funny you should mention "drive." Not too long ago I modded LOSER/Saturation and liteon/nonlinear to have master & slave controls (you can find the plugins here.) My plan is to add some crosstalk stuff to them. My ultimate goal is to get a good handle on JS/DSP programming and have some pretty good JS equivalents to things like Pro Tools Heat and Steven Slate's VCC. Not sure how close I'll get, but it's proving to be a great way to learn!
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Old 04-15-2011, 12:08 PM   #23
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If you start to feel extra adventurous with all this d.bop, something that I'm sure many would find extremely useful would be to emulate the saturation characteristics of various vintage and new input transformers. That's where much of the character and colour of certain tube preamps comes from.

It could be quite an undertaking though. There's a lot of possibility in emulating iron cores. There's input and output impedance, resonance, frequency response, core saturation characteristics, phase response... just to give you either inspiration or to scare you off the idea totally!!!!!

Seriously though, if you do tackle something like this, I'm more than happy to help you beta test. I have professional lab test gear that I can use to help you evaluate and tweak your creations. In other words, I can do real world physical tests on your plugins and make actual measurements of their characteristics so you can get closer to the actual physical counterparts you're modelling.

Just a little food for thought for ya!
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Old 04-16-2011, 11:19 AM   #24
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Originally Posted by Dannii View Post
If you start to feel extra adventurous with all this d.bop, something that I'm sure many would find extremely useful would be to emulate the saturation characteristics of various vintage and new input transformers. That's where much of the character and colour of certain tube preamps comes from.

It could be quite an undertaking though. There's a lot of possibility in emulating iron cores. There's input and output impedance, resonance, frequency response, core saturation characteristics, phase response... just to give you either inspiration or to scare you off the idea totally!!!!!

Seriously though, if you do tackle something like this, I'm more than happy to help you beta test. I have professional lab test gear that I can use to help you evaluate and tweak your creations. In other words, I can do real world physical tests on your plugins and make actual measurements of their characteristics so you can get closer to the actual physical counterparts you're modelling.

Just a little food for thought for ya!
Wow thank you so much dannii! I might just take you up on that in the future
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Old 04-16-2011, 11:27 PM   #25
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You're welcome
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Old 06-08-2011, 11:19 PM   #26
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I've been playing with Synthedit lately and I thought I should try working out a crosstalk type plugin just to see what it would sound like.
I whipped one up today and I think I got it pretty close to the graphs Dannii posted earlier in the thread.

Here are some screen captures of SPAN and my crosstalk plugin in action. (Pinkish color = crosstalk level)

Measured at 1kHz (0dB):


Pink noise:


In my tests, I used the pinknoisegen and tonegenerator JS plugins that are included with REAPER.



I'm not really sure if this is anything I'll use in the future.. but it's definitely a fun experiment. Tomorrow night I'm going to do some "real world" tests on the master, folders, and buses.
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Old 06-09-2011, 02:26 PM   #27
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Looking forward to hear your comments
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Old 06-09-2011, 04:25 PM   #28
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Quote:
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Looking forward to hear your comments
Thanks

I'm going to do a few tweaks and get the GUI sorted out. I'll release a "consumer-friendly" version soon.

I don't want to add any drive/saturation to this plugin. I like to keep things simple

Also, unfortunately I don't think crosstalk between tracks in a DAW is possible through a plugin. I think it would have to be something hard-coded into the DAW itself. But placing the crosstalk plugin on stereo tracks, buses, and the master (or anything else in stereo) does a pretty good job.

Anyway, VST coming soon
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Old 06-09-2011, 06:05 PM   #29
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No problem, just let us know how it works.
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Old 06-14-2011, 06:53 PM   #30
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Plugin has been released

You can find it here: http://forum.cockos.com/showthread.php?p=759587
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Old 06-14-2011, 07:34 PM   #31
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Quote:
Originally Posted by Dannii View Post
No disrespect meant here d.bop but this topic has put a little grin on my face

I've worked for years designing and building analog audio gear and one of the things I do my utmost to design OUT of the gear is crosstalk. Now I read of you writing software code to incorporate crosstalk INTO your emulations

Don't get me wrong, I reckon what you are doing is a cool thing and I'm all for good software emulations. I just found the irony as a hardware designer amusing.
What Dannii said.

Its fun to experiment, but bang for the buck, I'd worry the thing was good before messing it up
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Old 06-14-2011, 08:20 PM   #32
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What Dannii said.

Its fun to experiment, but bang for the buck, I'd worry the thing was good before messing it up
Yeah, to tell you the truth I hesitated to release this plugin. After thinking about it and then working on it for a little while, I realized that I just don't think it's something I'd want to use on every project. Someone might like it though. So here it is

The plugins I make are basically for personal use/experimentation. Fun stuff to mess with before bed.
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