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#1
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inline transformer question
Hello,
If you are sending a balanced line-level XLR signal to a mixer that has XLR mic preamp inputs, and 1/4" line level inputs, what's the solution? Can you simply keep the gain very low on the XLR input and run the cable into the mic preamp input? Or is it better to convert the XLR to a 1/4" at the end using one of those inline tranformers and sending the signal into the line input? Usually the idea of a direct box is to take an unbalanced instrument signal and balance it for a long cable run. But I'm actually looking to do the reverse: to take a +4 XLR balanced cable run and step it down to 1/4" instrument level at the end before going into the mixer. Is there a direct box that works in reverse like this? Maybe it's o.k. to simply run straight into the mic preamp and keep the gain low. But I'm not sure if that makes feedback more of a problem. |
#2
Posted to rec.audio.pro
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inline transformer question
On Sun, 14 Dec 2008 12:20:15 -0800 (PST), genericaudioperson
wrote: Hello, If you are sending a balanced line-level XLR signal to a mixer that has XLR mic preamp inputs, and 1/4" line level inputs, what's the solution? An XLR TRS 1/4" jack plug adapter or cable. |
#3
Posted to rec.audio.pro
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inline transformer question
genericaudioperson wrote:
Hello, If you are sending a balanced line-level XLR signal to a mixer that has XLR mic preamp inputs, and 1/4" line level inputs, what's the solution? Can you simply keep the gain very low on the XLR input and run the cable into the mic preamp input? Or is it better to convert the XLR to a 1/4" at the end using one of those inline tranformers and sending the signal into the line input? Usually the idea of a direct box is to take an unbalanced instrument signal and balance it for a long cable run. But I'm actually looking to do the reverse: to take a +4 XLR balanced cable run and step it down to 1/4" instrument level at the end before going into the mixer. Is there a direct box that works in reverse like this? Maybe it's o.k. to simply run straight into the mic preamp and keep the gain low. But I'm not sure if that makes feedback more of a problem. The complete story on this and related things is RaneNote #100, Sound System Interconnection. http://www.rane.com/note110.html -- ================================================== ====================== Michael Kesti | "And like, one and one don't make | two, one and one make one." mrkesti at hotmail dot com | - The Who, Bargain |
#4
Posted to rec.audio.pro
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inline transformer question
genericaudioperson wrote:
If you are sending a balanced line-level XLR signal to a mixer that has XLR mic preamp inputs, and 1/4" line level inputs, what's the solution? Use a cable. Can you simply keep the gain very low on the XLR input and run the cable into the mic preamp input? Or is it better to convert the XLR to a 1/4" at the end using one of those inline tranformers and sending the signal into the line input? Is the 1/4" input balanced or unbalanced? If it's unbalanced, do you really care that the line becomes unbalanced? If it's only a few feet you probably don't. Usually the idea of a direct box is to take an unbalanced instrument signal and balance it for a long cable run. But I'm actually looking to do the reverse: to take a +4 XLR balanced cable run and step it down to 1/4" instrument level at the end before going into the mixer. Is there a direct box that works in reverse like this? Okay, this is a totally different question. Instrument inputs want very high-impedance sources and part of the tone of the amp comes from that. A "Reamp Box" will do that job for you. Maybe it's o.k. to simply run straight into the mic preamp and keep the gain low. But I'm not sure if that makes feedback more of a problem. Wait, now you're talking about a mike preamp and not about an instrument amp? What are you really trying to do? --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#5
Posted to rec.audio.pro
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inline transformer question
genericaudioperson wrote:
If you are sending a balanced line-level XLR signal to a mixer that has XLR mic preamp inputs, and 1/4" line level inputs, what's the solution? Is the 1/4" input balanced? Do you want to keep it balanced? Can you simply keep the gain very low on the XLR input and run the cable into the mic preamp input? It depends on the source. Most mic inputs have about a 2.5K impedance, and most line level sources like to see at least twice that to get their full headroom without clipping. So if you were to put a pad in between that's designed to provide a higher impedance on the source side, that would be a better way to do it than just drop the gain down. Or is it better to convert the XLR to a 1/4" at the end using one of those inline tranformers and sending the signal into the line input? Insufficient data. See my first question. Usually the idea of a direct box is to take an unbalanced instrument signal and balance it for a long cable run. But I'm actually looking to do the reverse: to take a +4 XLR balanced cable run and step it down to 1/4" instrument level at the end before going into the mixer. Is there a direct box that works in reverse like this? That's usually called a ReAmp box (that's a commercial name). It's designed to go to a high impedance instrument input from a line level source. "Instrument level" is in the ballpark of line level but doesn't usually run as high. Maybe it's o.k. to simply run straight into the mic preamp and keep the gain low. But I'm not sure if that makes feedback more of a problem. What does feedback have to do with anything? I thought you were running line level signals, not microphones. Now, please, what's your REAL question? -- If you e-mail me and it bounces, use your secret decoder ring and reach me he double-m-eleven-double-zero at yahoo -- I'm really Mike Rivers ) |
#6
Posted to rec.audio.pro
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inline transformer question
On Dec 14, 1:20 pm, genericaudioperson
wrote: Hello, If you are sending a balanced line-level XLR signal to a mixer that has XLR mic preamp inputs, and 1/4" line level inputs, what's the solution? Can you simply keep the gain very low on the XLR input and run the cable into the mic preamp input? Or is it better to convert the XLR to a 1/4" at the end using one of those inline tranformers and sending the signal into the line input? Usually the idea of a direct box is to take an unbalanced instrument signal and balance it for a long cable run. But I'm actually looking to do the reverse: to take a +4 XLR balanced cable run and step it down to 1/4" instrument level at the end before going into the mixer. Is there a direct box that works in reverse like this? Maybe it's o.k. to simply run straight into the mic preamp and keep the gain low. But I'm not sure if that makes feedback more of a problem. What are the levels that the 1/4" input jacks designed to see? Are they balanced? How do you know that the 1/4" input jacks are designed for instrument (approx. -20dBV) level ? What is the length of the run? What is driving the signal? Mic preamp, mixer, or some other device such as a keyboard? Generally, it is a bad thing to throw away any gain that you already have and then bring it up later. That induces noise at the very least and distortion at the worst. If the levels aren't mismatched then use an adapter cable. As long as you aren't introducing a ground loop that will be the easiest most likely best solution. |
#7
Posted to rec.audio.pro
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inline transformer question
"genericaudioperson" wrote...
a bunch of seeming unrelated questions before this one... also not clear what this has to do with "inline tranformer question"? But I'm actually looking to do the reverse: to take a +4 XLR balanced cable run and step it down to 1/4" instrument level at the end before going into the mixer. Is there a direct box that works in reverse like this? http://en.wikipedia.org/wiki/Re-amp There are several commercial products which take line level and convert them to "instrument level" for exactly this application. Maybe it's o.k. to simply run straight into the mic preamp and keep the gain low. Almost certainly not. It is very doubtful that you can *reliably* crank the level of a +4 output down to "instrument level" which is something like 60dB difference or more. But I'm not sure if that makes feedback more of a problem. What does "feedback" have to do with this? Is this a reinforcement situation? |
#8
Posted to rec.audio.pro
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inline transformer question
"genericaudioperson" wrote ...
.... But I'm actually looking to do the reverse: to take a +4 XLR balanced cable run and step it down to 1/4" instrument level at the end before going into the mixer. Can you explain why you want to take +4 line level, knock it down to -60 instrument level, and then boost it back up to even something you can feed into the mic input when you already have a perfectly good line-level input (according to your own description)? This is quite probably the worst possible solution most of us could conceive of. If there are some mitigating circumstances here that make you consider such a bizzare scheme, you didn't mention them. What exactly are you trying to do here? Some might think you are just using a random question generator and have no Real-World applications in mind. (Oh, and a random subject-line as well.) |
#9
Posted to rec.audio.pro
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inline transformer question
"genericaudioperson" wrote in message
... If you are sending a balanced line-level XLR signal to a mixer that has XLR mic preamp inputs, and 1/4" line level inputs, what's the solution? Can you simply keep the gain very low on the XLR input and run the cable into the mic preamp input? Or is it better to convert the XLR to a 1/4" at the end using one of those inline tranformers and sending the signal into the line input? If the 1/4" line-level input is a TRS jack, it's balanced, and all you need is an XLR-F/TRS-M adapter. If the 1/4" line-level input is a TS jack, things are more difficult. One solution, not necessarily a good one, is to make an adapter which connects pin 2 of the XLR to the tip of a TS plug, pin 1 to the sleeve of the plug, and pin 3 to a 10k resistor the other end of which is connected to the sleeve. (I'm assuming, going with the percentages, that your balanced signal is electronically balanced, not transformer-coupled. If it's transformer-coupled it's a different story, but it probably isn't.) A better solution is to use a good-quality 1:1 line-level transformer and connect it between the XLR connector and the TS jack. That preserves common-mode rejection. You can get one from Jensen. It'll cost ya, though. A decent solution is to use a good-quality DI box to step the line-level signal down to mic level, then run it through the mic preamp. It has to be a good one, though; you can make one from a Jensen mic transformer. It'll cost ya, too. A horrible solution is to run it into the mic preamp by itself, unless you have a very unusual mic preamp on your mixer. Usually the idea of a direct box is to take an unbalanced instrument signal and balance it for a long cable run. But I'm actually looking to do the reverse: to take a +4 XLR balanced cable run and step it down to 1/4" instrument level at the end before going into the mixer. Is there a direct box that works in reverse like this? Not to my knowledge. But that doesn't matter, because your 1/4" input isn't at instrument level anyhow; it's a line-level input. You said so. Maybe it's o.k. to simply run straight into the mic preamp and keep the gain low. But I'm not sure if that makes feedback more of a problem. Well, once the mic preamp is into massive clipping, it'll compress the hell out of the signal, so I suppose it might be more likely to feed back. But that'll be the least of your worries. Peace, Paul |
#10
Posted to rec.audio.pro
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inline transformer question
Richard Crowley wrote:
Can you explain why you want to take +4 line level, knock it down to -60 instrument level Not to start a side discussion here, but "instrument level" for most of what we consider "instruments' in this context (guitar and bass pickups) is just a little lower than what most of us consider "line level." A hot guitar pickup, with the guitar strummed hard, can put out a good solid +6 dBu, with peaks 10 dB or more above that. The difference between an "instrument" input and a 1/4" line level jack is typically not in gain, but rather, in impedance. And instrument inputs, unless they have an input transformer, are never balanced. But you knew that. -- If you e-mail me and it bounces, use your secret decoder ring and reach me he double-m-eleven-double-zero at yahoo -- I'm really Mike Rivers ) |
#11
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inline transformer question
"Mike Rivers" wrote ...
Richard Crowley wrote: Can you explain why you want to take +4 line level, knock it down to -60 instrument level Not to start a side discussion here, but "instrument level" for most of what we consider "instruments' in this context (guitar and bass pickups) is just a little lower than what most of us consider "line level." A hot guitar pickup, with the guitar strummed hard, can put out a good solid +6 dBu, with peaks 10 dB or more above that. The difference between an "instrument" input and a 1/4" line level jack is typically not in gain, but rather, in impedance. And instrument inputs, unless they have an input transformer, are never balanced. But you knew that. Does the OP know *any* of that? I'm beginning to suspect another troll here. |
#12
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inline transformer question
Richard Crowley wrote:
Does the OP know *any* of that? I'm beginning to suspect another troll here. Probably not, but not everyone who doesn't know fundamentals is a troll. I suspect that he has heard the terms, knows that some units have an "instrument" input, and just didn't ask the right question. It happens all the time. You can either stand by the sideline and wait to see if the real problem emerges, or try to squeeze enough information (including what he really has and wants to accomplish) to give him a useful answer. That's my approach, most of the time. But not always. I'm not a saint. -- If you e-mail me and it bounces, use your secret decoder ring and reach me he double-m-eleven-double-zero at yahoo -- I'm really Mike Rivers ) |
#13
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inline transformer question
Wow, I didn't realize my question left so many unanswered questions!
The scenario is this: you have a submixer. then you want to send the balanced +4 xlr outputs to the main mixer (with about a 40 foot cable run). the main mixer has two choices: 1) xlr mic pre inputs 2) 1/4" line level inputs (which I'm guessing are unbalanced). So I guess the ideal situation would be to keep the cable run balanced all the way to near the mixer, and then use a converter box to step it down to 1/4" unbalanced at the last minute. I'm not getting appreciable clipping running the xlr signal into the main mixer preamp inputs.. But I wasn't sure if doing this is making the system more susceptible to feedback (by having too much gain before the power amp stage). this must be a common enough scenario that there is a standard box to make things the right way electronically. |
#14
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inline transformer question
On Mon, 15 Dec 2008 18:15:40 -0800 (PST), genericaudioperson
wrote: Wow, I didn't realize my question left so many unanswered questions! The scenario is this: you have a submixer. then you want to send the balanced +4 xlr outputs to the main mixer (with about a 40 foot cable run). the main mixer has two choices: 1) xlr mic pre inputs 2) 1/4" line level inputs (which I'm guessing are unbalanced). Why unbalanced? But more importantly, why guess? What is this mysterious "main mixer"? CH |
#15
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inline transformer question
genericaudioperson wrote:
Wow, I didn't realize my question left so many unanswered questions! The scenario is this: you have a submixer. then you want to send the balanced +4 xlr outputs to the main mixer (with about a 40 foot cable run). the main mixer has two choices: 1) xlr mic pre inputs 2) 1/4" line level inputs (which I'm guessing are unbalanced). I would find out if they are balanced or not, and I would NOT guess. So I guess the ideal situation would be to keep the cable run balanced all the way to near the mixer, and then use a converter box to step it down to 1/4" unbalanced at the last minute. You can use a transformer box to balance or unbalance the line, but I'd first make sure you don't have a balanced 1/4" input to begin with. I'm not getting appreciable clipping running the xlr signal into the main mixer preamp inputs.. But I wasn't sure if doing this is making the system more susceptible to feedback (by having too much gain before the power amp stage). Well, are the main inputs really mike inputs, or is this something like a Mackie where there is a very wide range of usable gain? this must be a common enough scenario that there is a standard box to make things the right way electronically. Everybody should have some 1:1 transformer boxes in the closet, but good ones aren't cheap and cheap ones usually aren't very good. These days since just about everything has electronically balanced inputs and outputs they aren't as important. But see, you don't even mention things like what kind of consoles you're using. And I'm STILL trying to figure out what any of this has to do with instrument level connections, which is what you seemed to be talking about in your first posting. Really, you need the Yamaha Sound Reinforcement Handbook. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#16
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inline transformer question
"genericaudioperson" wrote in ...
Wow, I didn't realize my question left so many unanswered questions! The scenario is this: you have a submixer. then you want to send the balanced +4 xlr outputs to the main mixer (with about a 40 foot cable run). the main mixer has two choices: 1) xlr mic pre inputs 2) 1/4" line level inputs (which I'm guessing are unbalanced). Why do you have to guess? Do you not know what kind of mixer it is? Perhaps you are learning from your last several questions that details are important, and frequently *critical*. You will always get more complete and more useful answers if you reveal the exact make and model of the equipment you are asking about. And the actual names of the connectors, etc, and what kind of cable (and connectors) you are using, etc. In many mixers (like Mackie, et.al.) the balanced line input goes through an internal pad into the balanced mic input, so the line input is fully balanced. So I guess the ideal situation would be to keep the cable run balanced all the way to near the mixer, and then use a converter box to step it down to 1/4" unbalanced at the last minute. If you have a line-level source and a line-level input, no "step- down" is necessary. A 40-foot run for a balanced line-level signal is *nothing*. Condider that the first "line-level" runs were miles long (Al Bell's original telephone system.) And in more recent times balanced line-level runs even hundreds of miles are not unknown. Remember that telephone and radio network signals went coast-to-coast on pairs of wires until less than 50 years ago with the advent of communication satellites. I'm not getting appreciable clipping running the xlr signal into the main mixer preamp inputs.. But I wasn't sure if doing this is making the system more susceptible to feedback (by having too much gain before the power amp stage). You might get away with it if you're lucky, but you're living on the edge and there is no good reason to do that. The proper cable and/ or connector adapters are dirt-cheap. The potential of feedback is not particularly an issue unless you don't keep the output of the source unusually low (because you are feeding a line-level source into a mic- level input). this must be a common enough scenario that there is a standard box to make things the right way electronically. A line-level source to a line-level input usually doesn't typically require ANY kind of "box", just an appropriate cable and connectors. |
#17
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inline transformer question
On Mon, 15 Dec 2008 18:15:40 -0800 (PST), genericaudioperson
wrote: you have a submixer. then you want to send the balanced +4 xlr outputs to the main mixer (with about a 40 foot cable run). the main mixer has two choices: 1) xlr mic pre inputs 2) 1/4" line level inputs (which I'm guessing are unbalanced). Don't guess, find out. If they ARE balanced, you can ignore the smokescreen and follow my original simple suggestion. |
#18
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inline transformer question
genericaudioperson wrote:
Wow, I didn't realize my question left so many unanswered questions! That's what happens when you ask too general or hypothetical question. The best answer, and the tradeoffs (there are always tradeoffs) depend on the application as much as on the question. you have a submixer. then you want to send the balanced +4 xlr outputs to the main mixer (with about a 40 foot cable run). the main mixer has two choices: 1) xlr mic pre inputs 2) 1/4" line level inputs (which I'm guessing are unbalanced). Would this 'you' be YOU? First off, don't guess about the 1/4" line level inputs. Either find out or simply assume that they're unbalanced. For a 40 foot run, it would be smart to run a balanced connection. So I guess the ideal situation would be to keep the cable run balanced all the way to near the mixer, and then use a converter box to step it down to 1/4" unbalanced at the last minute. Yup. But since it's line level from the submixer and you're going into a line level input on the main mixer, you need to use a 1:1 transformer, not a "mic adapter" transformer. This is a pretty common item. I'm not getting appreciable clipping running the xlr signal into the main mixer preamp inputs.. You're just not trying hard enough. g But sometimes this indeed works out OK sometimes. But it depends on the power available from the source and the load impedance of the mic input. In the case of Mackie mixers that have a Mic/Line level switch for the main XLR ouptuts, the attenuator that goes in line when in the Mic level position provides enough isolation from the low impedance load so that it doesn't affect the output stage of the mixer. But I wasn't sure if doing this is making the system more susceptible to feedback (by having too much gain before the power amp stage). Since you're reducing the gain by lowering the output of the submixer and/or lowering the gain of the preamp, you don't have too much gain. this must be a common enough scenario that there is a standard box to make things the right way electronically. It's not all that common, because of all the permutations of input and output connectors, but if you're willing to accept one or two adapters there are a number of relatively inexpensive choices. The Ebtech (Morely) Hum Eliminator is OK if you dont run the output of the submixer too hot. Jensen makes a whole line of transformers in many configurations for considerably more money, but they don't crap out when the levels get high. Sescom has some as well. -- If you e-mail me and it bounces, use your secret decoder ring and reach me he double-m-eleven-double-zero at yahoo -- I'm really Mike Rivers ) |
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