Hi..
I´m a real novice regarding patchbays, so here goes...
What is normalized, halfnormalized and unnormalized when it comes to patchbays?
Thankful for answers.. take care
Andy
Newbie patchbay question
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I tried a brief google to see if there was a good reference already out there; came up with nada, so here goes -
First of all, you probably already know WHY patch bays are used, but just in case - there are lots of times when a piece of gear would be handy to use in a different location in the signal path, or for a different track, etc - sometimes we want to be able to use an equalizer in the side chain of a compressor to change the way the compressor behaves at different frequencies (such as using the comp. for a De-Esser), - anyway, there are reasons why climbing behind the racks and temporarily re-wiring things is NOT a good way to go - one, it's difficult to get there, difficult to see what's wired to what, difficult to find the connections you want to move things to, and when you're finished using the gear that way it's even MORE fun to remember what all you changed in addition to ALL the other difficulties of reversing what you did...
The point of using patch bays, basically, is to put all the connections you may want to temporarily change out in FRONT of your setup, so you can SEE what you're doing, LABEL all of them so you know where they come from/go to, etc -
One way I've found that seems to work fairly well for choosing which connections get used on a patch bay - if you draw a connection diagram of all your gear, laid out in the order you "NORMALly" use the gear, you get a good picture of "normal" signal flow - (there's a reason I'm treating the word "normal" this way - more later)
Once you have this diagram, with lines between the boxes you drew representing each unit, you start at the beginning of the flow (like, the microphone, the guitar, etc, and look at each connection between each piece of gear, and ask yourself the question "would I EVER want to hook this up DIFFERENTLY?" - if the answer is yes, this is a good candidate for a patch bay connection. If not, then it can get wired directly between the two units.
Everywhere you decide you want a patch connection, you can put two horizontal "chevron" marks across the line that represents the connection -
------>>----- (the dashed lines would be solid, but there's no key on the computer for that)
these can then be assigned (and labeled)to a specific pair of patch points, and instead of wiring that connection straight from the first unit to the second, you use TWO wires - one from the first unit to the patch bay, and a second wire from the other half of the patch pair onward to the input of the second unit. A "patch point" is two front and two rear panel connectors on a patch bay, one mounted above the other - outputs are usually the upper connector of a pair, and it's common to use Left channel first, then Right channel as you go across the patch bay - so, for example, when looking at the front panel of the bay the top connector for #1 might be labeled Ch.1 Preamp OUt Left (abbreviated as necessary for space) and the bottom of #1 pair might be Compressor #1 Input Left - The #2 pair of points would be (top) Ch.1 Preamp Out Right, the bottom would be Compressor #1 Input Right, etc -
Once all your patch points have been decided, you need to then get into "normalling" -
I've noticed a few bays now seem to have easily removable "modules" that can be removed from the front panel (or rear) and turned around to different mounting positions, this allows easy selection between different normalling modes - I've not done hardwired bays recently so I'm not sure if there's anything similar in that type bay yet.
Definitions - "normalled" describes what inputs and outputs the patch bay will connect to each other with NO CABLES plugged into the FRONT - usually, bays get shipped with some sort of normalling already enabled. The types -
Full normal - plugging a cable into either pair of a patch point interrupts the signal, and the added cable becomes the only connection to that point.
Half normal - plugging a cable into ONE of the two connections (usually the bottom of the pair) disconnects the pair, making the new connection the ONLY one - plugging into the TOP connector just "taps" into the circuit, NOT breaking the original circuit.
Un-normalled - the two wires coming into the REAR of the bay are not connected to ANYTHING until you plug something into the FRONT connectors.
Hard-wired - all 4 connectors of a patch point are hardwired together - so you never interrupt the signal by plugging into the front, it's just a "mult point" - a place where you can tap into the signal to use it as an input to another piece of gear.
IMPORTANT - it's OK to electrically tie two INPUTS together, because neither one is trying to drive anything, they're only looking for a signal to amplify, or whatever that piece of gear does to the signal - it's DEFINITELY NOT OK to tie two OUTPUTS together - there's a VERY good chance that the stronger (lower impedance) one will DESTROY the weaker one if left for more than a few SECONDS -
This is why a lot of bays, especially ones that have plug-in connections at the rear, come from the factory HALF normalled - the top half , being connected to the OUTPUT of gear, is NOT normalled, meaning that when you plug into it, the circuit isn't broken - you've just "tapped into" the circuit, and can run that signal into another piece of gear without losing the signal that WAS going onward from the patch bay - if you plug into the BOTTOM of that pair, which is the INPUT to the NEXT piece of gear in your signal chain, you will BREAK the original connection so that you've just replaced the input with a different signal.
Most gear has pretty high input impedance and pretty low output impedance (meaning it can drive several inputs) so using the top, or output, connection of a patch bay to drive more than one input doesn't usually cause any problems, or even a noticeable level change.
The term "normal" was chosen for patch bays, for the simple reason that having a bunch of patch cables ALWAYS hanging from the front of the bay is messy looking, and can (depending on what's mounted where) interfere with getting to knobs and displays of other gear mounted in the rack – so, we decide what wiring configuration is "normal", and we wire the bays (and choose internal normalling jumpers) so that when we're doing things in the "Normal" way, there are NO CABLES hanging off the front of the bay – all the "normal" connections are happening in the rear, and inside the patch bay – typically, output of unit A going into #1 top rear, out #1 bottom rear, and into the INPUT of unit B - #2 point would be identical, except for the Right channel. #3 point would be the OUTPUT of unit B (left ch.) on top, and the INPUT (L.Ch) of unit C on the bottom connector, and so on.
As long as we use things "normally", we don't need many cables hooked to the front of the bay, things stay easier to use, and the place doesn't look like a spaghetti factory run amok – but any time we need to temporarily disconnect or re-route a piece of gear for something more unusual, we don't need to crawl behind the racks to do it – just grab a handful of patch cables and re-route things for that temporary operation, then unplug them when you're done.
In the more consumer oriented bays (the ones with plug-in connections in the rear) there are two main types of bays – balanced and un-balanced. The unbalanced are available in ¼" phone (common) and RCA (not so common) jacks – the RCA type have no "Normalling" function, since RCA jacks don't have a way for the connector to "push an auxiliary contact" out of the way. The balanced versions use TRS connectors, which are just a 3-circuit version of the ¼" phone connector – TRS stands for Tip, Ring, Sleeve, which are the three terminals on the connector. A stereo headphone connector is a TRS – the full-size ones are ¼", the newer variety (in headphones anyway) are called "mini" jacks. In signal wiring, the Tip is wired hot (pin 2 in an XLR connector), the Ring is wired cold (the "low" side of balanced signals, pin 3 of an XLR) and the Sleeve is wired to shield (Pin 1 of an XLR)
I think Aaron's done more of this recently than I have, so he will likely want to add to this – hopefully I've at least given you an idea of some of the terms and methods... Steve
First of all, you probably already know WHY patch bays are used, but just in case - there are lots of times when a piece of gear would be handy to use in a different location in the signal path, or for a different track, etc - sometimes we want to be able to use an equalizer in the side chain of a compressor to change the way the compressor behaves at different frequencies (such as using the comp. for a De-Esser), - anyway, there are reasons why climbing behind the racks and temporarily re-wiring things is NOT a good way to go - one, it's difficult to get there, difficult to see what's wired to what, difficult to find the connections you want to move things to, and when you're finished using the gear that way it's even MORE fun to remember what all you changed in addition to ALL the other difficulties of reversing what you did...
The point of using patch bays, basically, is to put all the connections you may want to temporarily change out in FRONT of your setup, so you can SEE what you're doing, LABEL all of them so you know where they come from/go to, etc -
One way I've found that seems to work fairly well for choosing which connections get used on a patch bay - if you draw a connection diagram of all your gear, laid out in the order you "NORMALly" use the gear, you get a good picture of "normal" signal flow - (there's a reason I'm treating the word "normal" this way - more later)
Once you have this diagram, with lines between the boxes you drew representing each unit, you start at the beginning of the flow (like, the microphone, the guitar, etc, and look at each connection between each piece of gear, and ask yourself the question "would I EVER want to hook this up DIFFERENTLY?" - if the answer is yes, this is a good candidate for a patch bay connection. If not, then it can get wired directly between the two units.
Everywhere you decide you want a patch connection, you can put two horizontal "chevron" marks across the line that represents the connection -
------>>----- (the dashed lines would be solid, but there's no key on the computer for that)
these can then be assigned (and labeled)to a specific pair of patch points, and instead of wiring that connection straight from the first unit to the second, you use TWO wires - one from the first unit to the patch bay, and a second wire from the other half of the patch pair onward to the input of the second unit. A "patch point" is two front and two rear panel connectors on a patch bay, one mounted above the other - outputs are usually the upper connector of a pair, and it's common to use Left channel first, then Right channel as you go across the patch bay - so, for example, when looking at the front panel of the bay the top connector for #1 might be labeled Ch.1 Preamp OUt Left (abbreviated as necessary for space) and the bottom of #1 pair might be Compressor #1 Input Left - The #2 pair of points would be (top) Ch.1 Preamp Out Right, the bottom would be Compressor #1 Input Right, etc -
Once all your patch points have been decided, you need to then get into "normalling" -
I've noticed a few bays now seem to have easily removable "modules" that can be removed from the front panel (or rear) and turned around to different mounting positions, this allows easy selection between different normalling modes - I've not done hardwired bays recently so I'm not sure if there's anything similar in that type bay yet.
Definitions - "normalled" describes what inputs and outputs the patch bay will connect to each other with NO CABLES plugged into the FRONT - usually, bays get shipped with some sort of normalling already enabled. The types -
Full normal - plugging a cable into either pair of a patch point interrupts the signal, and the added cable becomes the only connection to that point.
Half normal - plugging a cable into ONE of the two connections (usually the bottom of the pair) disconnects the pair, making the new connection the ONLY one - plugging into the TOP connector just "taps" into the circuit, NOT breaking the original circuit.
Un-normalled - the two wires coming into the REAR of the bay are not connected to ANYTHING until you plug something into the FRONT connectors.
Hard-wired - all 4 connectors of a patch point are hardwired together - so you never interrupt the signal by plugging into the front, it's just a "mult point" - a place where you can tap into the signal to use it as an input to another piece of gear.
IMPORTANT - it's OK to electrically tie two INPUTS together, because neither one is trying to drive anything, they're only looking for a signal to amplify, or whatever that piece of gear does to the signal - it's DEFINITELY NOT OK to tie two OUTPUTS together - there's a VERY good chance that the stronger (lower impedance) one will DESTROY the weaker one if left for more than a few SECONDS -
This is why a lot of bays, especially ones that have plug-in connections at the rear, come from the factory HALF normalled - the top half , being connected to the OUTPUT of gear, is NOT normalled, meaning that when you plug into it, the circuit isn't broken - you've just "tapped into" the circuit, and can run that signal into another piece of gear without losing the signal that WAS going onward from the patch bay - if you plug into the BOTTOM of that pair, which is the INPUT to the NEXT piece of gear in your signal chain, you will BREAK the original connection so that you've just replaced the input with a different signal.
Most gear has pretty high input impedance and pretty low output impedance (meaning it can drive several inputs) so using the top, or output, connection of a patch bay to drive more than one input doesn't usually cause any problems, or even a noticeable level change.
The term "normal" was chosen for patch bays, for the simple reason that having a bunch of patch cables ALWAYS hanging from the front of the bay is messy looking, and can (depending on what's mounted where) interfere with getting to knobs and displays of other gear mounted in the rack – so, we decide what wiring configuration is "normal", and we wire the bays (and choose internal normalling jumpers) so that when we're doing things in the "Normal" way, there are NO CABLES hanging off the front of the bay – all the "normal" connections are happening in the rear, and inside the patch bay – typically, output of unit A going into #1 top rear, out #1 bottom rear, and into the INPUT of unit B - #2 point would be identical, except for the Right channel. #3 point would be the OUTPUT of unit B (left ch.) on top, and the INPUT (L.Ch) of unit C on the bottom connector, and so on.
As long as we use things "normally", we don't need many cables hooked to the front of the bay, things stay easier to use, and the place doesn't look like a spaghetti factory run amok – but any time we need to temporarily disconnect or re-route a piece of gear for something more unusual, we don't need to crawl behind the racks to do it – just grab a handful of patch cables and re-route things for that temporary operation, then unplug them when you're done.
In the more consumer oriented bays (the ones with plug-in connections in the rear) there are two main types of bays – balanced and un-balanced. The unbalanced are available in ¼" phone (common) and RCA (not so common) jacks – the RCA type have no "Normalling" function, since RCA jacks don't have a way for the connector to "push an auxiliary contact" out of the way. The balanced versions use TRS connectors, which are just a 3-circuit version of the ¼" phone connector – TRS stands for Tip, Ring, Sleeve, which are the three terminals on the connector. A stereo headphone connector is a TRS – the full-size ones are ¼", the newer variety (in headphones anyway) are called "mini" jacks. In signal wiring, the Tip is wired hot (pin 2 in an XLR connector), the Ring is wired cold (the "low" side of balanced signals, pin 3 of an XLR) and the Sleeve is wired to shield (Pin 1 of an XLR)
I think Aaron's done more of this recently than I have, so he will likely want to add to this – hopefully I've at least given you an idea of some of the terms and methods... Steve
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Aaronw
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I just recently added a link under the technical resources sticky. But here's a link that will give you some good info:
http://www.patchbays.com/norm_ground.htm
I didn't have a chance to read the lengthy reply from steve above yet. I just popped into the office for a quick minute due to our network crashing.
Damn Microsoft crap...
I'll post more next week after the holidays. Now it's time to go throw them ribs on the grill...
Aaron
http://www.patchbays.com/norm_ground.htm
I didn't have a chance to read the lengthy reply from steve above yet. I just popped into the office for a quick minute due to our network crashing.
Damn Microsoft crap...I'll post more next week after the holidays. Now it's time to go throw them ribs on the grill...
Aaron
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Aaronw
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Aaronw
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Most of depends on the signal path of the console.It's Still confusing to me as far as what type of equipment you use for normalized mode or not? like a quadraverb, midiverb? I guess I don't understand balanced/unbalanced, normalized etc?
Example: A console's channel (Inserts) are usually wired "Half-Normalled". Meaning, when you plug a patch cord into the top row (send from channel) the signal is still hard wired to the lower patch point on the bay. If you've ever plugged a cable in, you notice the sound still passes through, but you also have the signal on the cable you just patched that you will plug into a compressor or other outboard gear (which by the way, is denormalled so you don't cause a feedback loop w/ the gear). Then from the output of the gear, you plug back into the bottom row of the insert, causing the normalled connection to break and now using the signal from the outboard gear.
Another example (in your case the reverbs), perform a normal connection from the aux send(s) to the input of your reverb. The output of the verb is then normalled into the aux returns. This way, there is no patching required, however, if you decided to reroute the signal for some other use, it breaks the connection and sends it elsewhere. What I mean, let's say you decided to have the outputs go from the normalled return to the aux returns. Well, you want them to come up on a pair of channels instead for better control or automated effects. Patch the cord from the verb output (which then breaks the normalled connection to the aux return) and repatch/reroute into a channel input.
If you're still confused, I'll try and do some diagrams when I have a moment. (Been extremely busy at work lately).
Aaron
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Aaronw
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Nemesys
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From time to time on the various recording bulletin boards, I read of people who insist that that you shouldn't run microphones through patchbays and then into the preamps. I'm sure that they really mean that you shouldn;t do that when you want a high degree of purity and when you['ve got really good clea preamps (i.e. Earthworks, Sytek, Grace, etc...).... but some people just seem to have a strong opinion on this.
I'm wondering.... WHY?
I can understand that "theoretically" this is probably a good idea.... but considering that a patchbay uses basically passive components (jacks) and is for all intents and purposes a wire with I might assume very little resistance (I've never actually measures the resistance though). The only rationale that I could possibly see is that depending upon the patchbays design, you may have some "hum" issues if current manages to leak across the various modules.... which I'm sure it does in infintessimal amounts.....
I have a variety of ultra low noise preamps and so this is of interest to me. However, from my practical testing... I've never noticed any additional noise being picked up by patch bays as opposed to just running the mic straight into the preamp. I use WAVELAB, so I pretty much get a dead-on A/B comparison of the noise floor. SO I dont see the need for hooking the mike directly into the preamp.
If anyone has an opinion on this, lemme know.
I'm wondering.... WHY?
I can understand that "theoretically" this is probably a good idea.... but considering that a patchbay uses basically passive components (jacks) and is for all intents and purposes a wire with I might assume very little resistance (I've never actually measures the resistance though). The only rationale that I could possibly see is that depending upon the patchbays design, you may have some "hum" issues if current manages to leak across the various modules.... which I'm sure it does in infintessimal amounts.....
I have a variety of ultra low noise preamps and so this is of interest to me. However, from my practical testing... I've never noticed any additional noise being picked up by patch bays as opposed to just running the mic straight into the preamp. I use WAVELAB, so I pretty much get a dead-on A/B comparison of the noise floor. SO I dont see the need for hooking the mike directly into the preamp.
If anyone has an opinion on this, lemme know.
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Aaronw
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Nemesys,
Most of this has been answered here: http://johnlsayers.com/phpBB2/viewtopic.php?t=2023
One of the main concerns is phantom power.
Aaron
Most of this has been answered here: http://johnlsayers.com/phpBB2/viewtopic.php?t=2023
One of the main concerns is phantom power.
Aaron
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Nemesys
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Yeah, I saw that message thread already. I see no problem with running phantom through patchbays... just godda' be careful as that other message thread said.Aaronw wrote:Nemesys, Most of this has been answered here:
One of the main concerns is phantom power.
Anyway, I wasn't really talking about that. Theres some people out there who have wierd beliefs about patch bays. I have also seen guys who swear that you shouldnt run any device thrugh a patchbay which is MIDI controlled (because they swear up and down that latency will cause problems - which is just idiotic beyond all belief)..... I've heard that MIDI device urban myth several times from musicians I know.... that aside from the people who think patchays add noise to a microphone signal.
Anyway, thanks for the help.