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+4db, -10db...what does all this mean exactly?
Old 5th December 2014
  #61
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Quote:
Originally Posted by Julian Lojasound View Post
And how to convert a +4 output in a -10 signal? I want to connect my mixer balanced monitor out to my speakers amp (rca). My mixer out converts the output in unbalanced if you plug a TS but i think the signal level is the same, +4db.
Turn your monitor outputs down.
Old 30th December 2014
  #62
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Quote:
Originally Posted by FFTT View Post
The problem I had going from my DAV BG-1 into my M-Audio ProjectMix I/O
was that M-Audio never intended their interface to be used with outboard +4 professional gear.

It was designed as an All-In-One prosumer unit, with Their preamps and converters, assuming you were just plugging in a mic or instrument direct.

M-Audio-Digi Rep told me I had 1 input, the front guitar jack that does not route the signal through their preamps, so I had to use an XLR to TS cable going out of the DAV-BG1.

I considered going to Apogee, but the Apogee rep said they handle +4 input signal with a virtual software pad.

Future project studio interface designers might want to provide at least 2 I/O's
where you can totally bypass their internal preamps running outboard +4 gear.
I'm way late to the party on this one, but I'm just poking around looking at interesting threads...

M-Audio-Digi Rep told me I had 1 input, the front guitar jack that does not route the signal through their preamps ...

I'm not going to make a definitive claim either way as I've never even seen a ProjectMix I/O, but that just doesn't sound right to me.

Typically, if an interface has an instrument input, pressing the "Inst" switch (or however the switching is handled) simply adjusts the input impedance of the preamp, but the signal still goes through the preamp.

If, as the M-Audio guy said, the instrument input does not go through the preamp, where does its gain come from?
Old 9th January 2015
  #63
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I have a question: What would I set my Apogee Quartet Maestro software to if I wanted to run it with my UA 6176 and bi-pass the Quartets Pre amp? -10db or +4db? I want the proper gain stage. I believe the UA 6176 has a balanced output. Thanks!
Old 10th January 2015
  #64
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Something like -10 dB could also mean that the master fader is to be pulled down by 10 dB, but usually one is asked to render a mix at -6 dB. This is when sending it in for mastering.

But yeah, i guess we're talking about preamps so… just thought i'd mention it.
Old 11th January 2015
  #65
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Quote:
Originally Posted by hoolijin View Post
I have a question: What would I set my Apogee Quartet Maestro software to if I wanted to run it with my UA 6176 and bi-pass the Quartets Pre amp? -10db or +4db? I want the proper gain stage. I believe the UA 6176 has a balanced output. Thanks!
You would set both devices to +4...this is the typical level for "pro audio" gear. About the only time you would use -10 on an input is if you were interfacing something like a "consumer" CD player.

You would then use an XLR-F x 1/4" TRS balanced cable to connect the 6176 to the Quartet. Check the 6176 manual regarding which outputs on the 6176 you should use.

BUT...

You can't bypass the Quartet's preamps...more here: https://www.sweetwater.com/forums/sh...Apogee-Quartet
Old 11th January 2015
  #66
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Quote:
Originally Posted by Leumas Fyzz View Post
Something like -10 dB could also mean that the master fader is to be pulled down by 10 dB, but usually one is asked to render a mix at -6 dB. This is when sending it in for mastering.

But yeah, i guess we're talking about preamps so… just thought i'd mention it.
I'm afraid your info is way off on this...

First, using terms like "-10db or +4db" is like a sign by a road that reads, "Speed Limit 60". The speedometer is marked in both "miles per hour" and "kilometers per hour"...so which unit is the "60" on the speed limit sign referring to?

The correct terms are "+4dBu" and "-10dBV"...the "u" and the "V" indicate which measurement scale is being used...and there is not simply a "14 dB" difference between the two.

The "dB" unit is used with a lot of different measurement scales to measure a variety of different things, so it is a somewhat complex topic. Which leaves you with two options for learning how to use dB: the "correct" method, or the "Bill" method.

In the "correct" method, one learns all of the engineering and math necessary to understand where the unit "dB" comes from, how all of the different measurement "scales" were developed, and the proper application of each.

In the "Bill" method, I start with the fact that I wear a size 10-1/2 US shoe. I have no idea whether 10-1/2 refers to inches, meters, time of day, or the amount of beer in my glass...neither do I care...I simply know that a size 10-1/2 US shoe fits me, other sizes do not.

So it is with interconnecting audio gear...I know that if I am connecting +4 dBu to +4 dBu or -10 dBV to -10 dBV the levels will be fine, but if I am connecting a +4 dBu and a -10 dBV I will need to compensate for the different levels.

Regarding "Something like -10 dB could also mean that the master fader is to be pulled down by 10 dB, but usually one is asked to render a mix at -6 dB. This is when sending it in for mastering", I'm afraid that has absolutely nothing to do with this topic...
Old 12th January 2015
  #67
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Leumas Fyzz's Avatar
Quote:
Originally Posted by bdenton View Post
I'm afraid your info is way off on this...

First, using terms like "-10db or +4db" is like a sign by a road that reads, "Speed Limit 60". The speedometer is marked in both "miles per hour" and "kilometers per hour"...so which unit is the "60" on the speed limit sign referring to?

The correct terms are "+4dBu" and "-10dBV"...the "u" and the "V" indicate which measurement scale is being used...and there is not simply a "14 dB" difference between the two.

The "dB" unit is used with a lot of different measurement scales to measure a variety of different things, so it is a somewhat complex topic. Which leaves you with two options for learning how to use dB: the "correct" method, or the "Bill" method.

In the "correct" method, one learns all of the engineering and math necessary to understand where the unit "dB" comes from, how all of the different measurement "scales" were developed, and the proper application of each.

In the "Bill" method, I start with the fact that I wear a size 10-1/2 US shoe. I have no idea whether 10-1/2 refers to inches, meters, time of day, or the amount of beer in my glass...neither do I care...I simply know that a size 10-1/2 US shoe fits me, other sizes do not.

So it is with interconnecting audio gear...I know that if I am connecting +4 dBu to +4 dBu or -10 dBV to -10 dBV the levels will be fine, but if I am connecting a +4 dBu and a -10 dBV I will need to compensate for the different levels.

Regarding "Something like -10 dB could also mean that the master fader is to be pulled down by 10 dB, but usually one is asked to render a mix at -6 dB. This is when sending it in for mastering", I'm afraid that has absolutely nothing to do with this topic...
Good point. What i mentioned then is what is called dBfs, is it? (also newbie)
Old 12th January 2015
  #68
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Quote:
Originally Posted by Leumas Fyzz View Post
Good point. What i mentioned then is what is called dBfs, is it? (also newbie)
Right...that would be dBFS...unfortunately, I was already falling asleep when I finished my post, and whereas the other stuff deals with absolutes, there is a certain amount of opinion in recording levels so I decided to just let that one slide.

(Note...the following is greatly simplified...I'll try to give you useful stuff, but a certain amount of it will be basically just telling you what to Google.)

In the analog world, clipping will result in distortion, which sometimes can be a nice addition to the overall tone. And there is no absolute point on a meter where clipping will occur...it depends on the design and type of the equipment being used.

In the digital world, clipping results in a sound most folks find extremely unpleasant...it is not something folks would use as an effect (although some people will use any sound they find!) And, unlike with analog, we can have a meter that shows us exactly where digital clipping will always begin.

This point is marked with a 0 on a digital level meter, and is referred to as 0 dB Full Scale, or 0 dBFS.

With today's music, it is typically recorded so the peaks (loudest parts of the music) are right at 0 dBFS, which gives the loudest possible recording.

As music goes through the typical production workflow of tracking (the initial recording of the instruments and voices), mixing (combining the tracks to create a "cohesive" whole), and mastering (preparing the mix for release in the desired format), the level ("loudness") of the recording is gradually increased.

So, to end up with the final recording having peaks at 0 dBFS, we must start with a recording at a level far enough below 0 dBFS to accommodate the level increases that occur during the production workflow.

And this is where opinion comes into play, as we decide what the level of the initial recording should be.

I have seen recommendations of everything from peaks at -6 dBFS to an average of -20 dBFS...and there is no agreement as to whether this "starting" level should be "specified" as peaks or average.

Now, I will tell you what I use, and they are based on recommendations from several engineers whose opinions I respect. These just happen to correspond with what is often suggested as "starting" levels, to be varied slightly according to the project at hand. But keep in mind these are just my opinion...others may have differing opinions that are equally valid.

When tracking, I like to end up with average levels between -15 dBFS and -18 dBFS. After mixing, I like to have peak levels between -3 dBFS and -6 dBFS.

These levels typically give me tracks that are recorded at the highest possible level, while leaving enough headroom to accommodate the sometimes relatively large level increase that occurs during the mixing process, while leaving enough headroom for the mastering engineer to do his/her magic and end up with peaks at 0dBFS.

Remember that these levels are just my opinion, and you should do your own research and testing to determine the optimal levels for your production process.

But never allow your peaks to go above 0 dBFS or your head will explode and your kids will all be born naked...
Old 12th January 2015
  #69
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Leumas Fyzz's Avatar
Quote:
Originally Posted by bdenton View Post
Right...that would be dBFS...unfortunately, I was already falling asleep when I finished my post, and whereas the other stuff deals with absolutes, there is a certain amount of opinion in recording levels so I decided to just let that one slide.

(Note...the following is greatly simplified...I'll try to give you useful stuff, but a certain amount of it will be basically just telling you what to Google.)

In the analog world, clipping will result in distortion, which sometimes can be a nice addition to the overall tone. And there is no absolute point on a meter where clipping will occur...it depends on the design and type of the equipment being used.

In the digital world, clipping results in a sound most folks find extremely unpleasant...it is not something folks would use as an effect (although some people will use any sound they find!) And, unlike with analog, we can have a meter that shows us exactly where digital clipping will always begin.

This point is marked with a 0 on a digital level meter, and is referred to as 0 dB Full Scale, or 0 dBFS.

With today's music, it is typically recorded so the peaks (loudest parts of the music) are right at 0 dBFS, which gives the loudest possible recording.

As music goes through the typical production workflow of tracking (the initial recording of the instruments and voices), mixing (combining the tracks to create a "cohesive" whole), and mastering (preparing the mix for release in the desired format), the level ("loudness") of the recording is gradually increased.

So, to end up with the final recording having peaks at 0 dBFS, we must start with a recording at a level far enough below 0 dBFS to accommodate the level increases that occur during the production workflow.

And this is where opinion comes into play, as we decide what the level of the initial recording should be.

I have seen recommendations of everything from peaks at -6 dBFS to an average of -20 dBFS...and there is no agreement as to whether this "starting" level should be "specified" as peaks or average.

Now, I will tell you what I use, and they are based on recommendations from several engineers whose opinions I respect. These just happen to correspond with what is often suggested as "starting" levels, to be varied slightly according to the project at hand. But keep in mind these are just my opinion...others may have differing opinions that are equally valid.

When tracking, I like to end up with average levels between -15 dBFS and -18 dBFS. After mixing, I like to have peak levels between -3 dBFS and -6 dBFS.

These levels typically give me tracks that are recorded at the highest possible level, while leaving enough headroom to accommodate the sometimes relatively large level increase that occurs during the mixing process, while leaving enough headroom for the mastering engineer to do his/her magic and end up with peaks at 0dBFS.

Remember that these levels are just my opinion, and you should do your own research and testing to determine the optimal levels for your production process.

But never allow your peaks to go above 0 dBFS or your head will explode and your kids will all be born naked...

Very informative for the newbie. Thank you for taking the time!
Old 12th January 2015
  #70
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Quote:
Originally Posted by Leumas Fyzz View Post
Very informative for the newbie. Thank you for taking the time!
Hey...a lot of people have helped me along the way, the least I can do is give it back by helping others...
Old 24th January 2015
  #71
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Thanks all for the input (no pun intended) and thank you for clearing up my question and in incorrect "4Db" quote. Awesome, so I won't be able to bi-pass my Quartet like I was able to with my Diet 2? Or was I really not bi-passing that pre amp all the way anyway? Thanks again!

And yes, this wasn't for master fader stuff, I meant to say +4dBu.
Old 12th February 2015
  #72
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Quote:
never allow your peaks to go above 0 dBFS or your head will explode and your kids will all be born naked...
I couldn't stop laughing when I read this!

By the same token, never let your peaks go below negative zero dBFS. Same consequence.
Old 24th February 2015
  #73
Quote:
Originally Posted by FFTT View Post
Chris at Redco recommended the Rolls Promatch MB15b Two way stereo converter
to help tame those +4 signals when going into -10 gear.

Rolls Corporation - Real Sound - Products MB15b Promatch and More

Aphex also makes one of these. Very useful device.
Old 24th February 2015
  #74
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Actually, I learned later that a simple XLR to 1/4" TRS cable going into my interface line inputs solved the too much gain issue.

Haven't had problem since and my BG-1 stays up & ready to go.
Old 24th February 2015
  #75
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Newbie with Expensive

I have an MXL Genesis II Mic routed to my 10th Anniversary Avalon 737sp to my Fireface UFX Interface to my Mackie Big knob through my Yamaha Monitors! I am recording in a portable booth I purchased from Clear sonic as well!

The Daw I am most comfortable with is Studio ONE because my best friend recorded some of my best jams here and taught me the basics before he passed away last christmas.

I need to know if I am bringing the best raw signal through my system to be mixed!

Can someone please help?
Old 7th March 2015
  #76
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what is interesting about this thread is we have guys with totally varying experience across years of different equipment and standards. The terms +4 and -10 on the surface are just about signal levels.. but when you look at the reality, you have to be specific about the equipment that you are refering to when you use the terms. The standards have been around long enough that +4 could be a low impedance differential electronic output, or a low impedance balanced transformer output, or a low impedance electronic input.. or a low impedance transformer balanced input. -10 would have to be either an unbalanced RCA input, or an unbalanced RCA output, or a unbalanced 1/4" mono input, or a 1/4" mono output. Connecting a balanced +4 output to an unbalanced -10 input will require the unbalancing of the balanced output, which will lower the level by 6dB in the process.. and then you are still about 6dB too hot. By the same token, if you connect a -10 db, unbalanced output (RCA or 1/4") to a balanced input.. you are unbalancing the input and dropping the signal again by 6dB in the process. It's always something! Just an observation.
Old 1st April 2015
  #77
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Quote:
Originally Posted by bdenton View Post
You would set both devices to +4...this is the typical level for "pro audio" gear. About the only time you would use -10 on an input is if you were interfacing something like a "consumer" CD player.

You would then use an XLR-F x 1/4" TRS balanced cable to connect the 6176 to the Quartet. Check the 6176 manual regarding which outputs on the 6176 you should use.

BUT...

You can't bypass the Quartet's preamps...more here: https://www.sweetwater.com/forums/sh...Apogee-Quartet
I agree, My understanding is that +4db= 0db VU which is what you will find for Pro Gear
Old 22nd April 2015
  #78
Gear Head
hey guys i have an apogee ensemble hooked up to some hs8 monitors. when i set the outputs on the ensemble to +4 i get a much more present noise floor. its not noticeable with music playing but it bothers me anyway. is this hum normal? the speakers are both set to +4 on the backs
Old 1st May 2015
  #79
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Hi
Quote:
The standards have been around long enough that +4 could be a low impedance differential electronic output, or a low impedance balanced transformer output, or a low impedance electronic input.. or a low impedance transformer balanced input. -10 would have to be either an unbalanced RCA input, or an unbalanced RCA output, or a unbalanced 1/4" mono input, or a 1/4" mono output. Connecting a balanced +4 output to an unbalanced -10 input will require the unbalancing of the balanced output, which will lower the level by 6dB in the process.. and then you are still about 6dB too hot. By the same token, if you connect a -10 db, unbalanced output (RCA or 1/4") to a balanced input.. you are unbalancing the input and dropping the signal again by 6dB in the process. It's always something! Just an observation.
Unquote:

Not all true.
+4dBu and -10dBV are REFERENCE (usually) voltage levels that typically give the optimal signal to noise ratio and distortion in an analogue system. The circuitry inside is optimised for this level.
The TYPE of connector, XLR, TRS,RCA or any other has NO bearing on signal voltage levels and apart from the fact you can't manage a balanced connection using a TR jack or RCA connector, the connector type does not 'define' signal as being balanced or unbalanced.
As a third situation, how balanced and unbalanced interconnections interact with each other MAY or MAY NOT give you a 6db 'loss' of level and this is defined by the specific circuitry involved.
Thus you have LEVEL, Connector and 'Balance' as 3 main considerations for any interconnection and you must specify ALL 3 to get a true meaning. There is also a question of impedance but this ranks 4th in the list of specification and the effect of unsuitable impedance 'matching' is a subject all of it's own but for most modern gear can be largely ignored as the guys (gals) in lab coats have sorted most of it out for you.
Matt S
Old 1st May 2015
  #80
Thumbs up

Quote:
Originally Posted by Matt Syson View Post
Hi
Quote:
The standards have been around long enough that +4 could be a low impedance differential electronic output, or a low impedance balanced transformer output, or a low impedance electronic input.. or a low impedance transformer balanced input. -10 would have to be either an unbalanced RCA input, or an unbalanced RCA output, or a unbalanced 1/4" mono input, or a 1/4" mono output. Connecting a balanced +4 output to an unbalanced -10 input will require the unbalancing of the balanced output, which will lower the level by 6dB in the process.. and then you are still about 6dB too hot. By the same token, if you connect a -10 db, unbalanced output (RCA or 1/4") to a balanced input.. you are unbalancing the input and dropping the signal again by 6dB in the process. It's always something! Just an observation.
Unquote:

Not all true.
+4dBu and -10dBV are REFERENCE (usually) voltage levels that typically give the optimal signal to noise ratio and distortion in an analogue system. The circuitry inside is optimised for this level.
The TYPE of connector, XLR, TRS,RCA or any other has NO bearing on signal voltage levels and apart from the fact you can't manage a balanced connection using a TR jack or RCA connector, the connector type does not 'define' signal as being balanced or unbalanced.
As a third situation, how balanced and unbalanced interconnections interact with each other MAY or MAY NOT give you a 6db 'loss' of level and this is defined by the specific circuitry involved.
Thus you have LEVEL, Connector and 'Balance' as 3 main considerations for any interconnection and you must specify ALL 3 to get a true meaning. There is also a question of impedance but this ranks 4th in the list of specification and the effect of unsuitable impedance 'matching' is a subject all of it's own but for most modern gear can be largely ignored as the guys (gals) in lab coats have sorted most of it out for you.
Matt S
I need to add this to my Evernote. Best explanation I could pass on.

Thanks,
Old 24th May 2015
  #81
I just switched all my gear to +4 because I had it all at -10(I wasn't sure what it was all about) now everything is really loud and I have to stick the faders down really low in my daw so I don't clip on my mixer. I'm wondering if I have to set my daw to meter differently?? I'm on cubase 7.5. It's not that big of a deal I'll just have to set the meters down lower but all my previous mixes will hit my mackie hard.
I go out from my daw to a mackie 1402vlz then back in to the daw. I use the mixer for monitoring and to run all my synths into my daw. If I turn the master fader on the mackie down it doesn't clip but it can't stay at unity or it will get blasted.
Old 27th May 2015
  #82
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Great thread, an excellent read, thanks to all posters!

So, a question then. Recently I was experimenting with the levels between my interface (an RME Multiface I) and monitors (Dynaudio BM6a, originals). The interface's analog outputs can be set (via jumper) to +4 or -10. Similarly, the monitors have a switch on the back to set input sensitivity between +4 and -10.

I have always used both at +4. But recently I set one pair of outputs on the RME to -10. What I have seen is that when I use these -10 outputs directly into the dynaudios (set to -10 input sensitivity) the sound is noticeably louder than when using two different RME outputs (set at +4) with the monitors' input sensitivity at +4. I would have thought that the loudness would be equivalent, but it is CLEARLY louder at -10.

Audio material is exactly the same, cables are the same (balanced male XLR to TRS, mogami), software mixer levels all the same. I'm literally just moving the cables on the interface and flipping a switch on the monitors, then playing back the same file.

Below specs from the RME manual:

RME Multiface:

DA

Resolution: 24 bit
Signal to Noise ratio: 108 dB RMS unweighted, 111 dBA (unmuted)
THD: < -98 dB, < 0.0013 %
THD+N: < **** dB, < 0.002 %
Crosstalk: > 100 dB
Maximum output level: +19 dBu
Frequency response DA @ 44.1 kHz, -0.5 dB: 5 Hz – 20.9 kHz
Frequency response DA @ 96 kHz, -0.5 dB: 5 Hz - 35 kHz
Output: 6.3 mm TRS jack, servo-balanced
Output impedance: 47 Ohm
Output level by jumper: Hi Gain, +4 dBu,-10 dBV
Output level at 0 dBFS @ Hi Gain: +19 dBu
Output level at 0 dBFS @ +4 dBu: +13 dBu
Output level at 0 dBFS @ -10 dBV: +2 dBV

Dynaudio Manual just acknowledges the existence of input sensitivity switch, but does not provide details on numbers relating to dB or anything similar.


Any ideas?
Old 2nd July 2015
  #83
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Somebody please correct me if I am wrong, but are the following assumptions accurate?

In simple terms:

1. If your output says -10 the output level will be lower than if the output says +4*

2. If your input says / is set to -10 it will be expecting a lower signal than +4 and will amplify it, whereas the +4 input will be expecting a hotter signal.

3. This means with the same output / source level a +4 input setting will be quieter* than a -10 input setting, if you have the option of choosing.

*By 11.79db apparently.

Point 3 is where I'm not sure as it seems counter intuitive, the lower setting giving the louder result.
Old 6th July 2015
  #84
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Quote:
Originally Posted by dontsimon View Post
Somebody please correct me if I am wrong, but are the following assumptions accurate?

In simple terms:

1. If your output says -10 the output level will be lower than if the output says +4*

2. If your input says / is set to -10 it will be expecting a lower signal than +4 and will amplify it, whereas the +4 input will be expecting a hotter signal.

3. This means with the same output / source level a +4 input setting will be quieter* than a -10 input setting, if you have the option of choosing.

*By 11.79db apparently.

Point 3 is where I'm not sure as it seems counter intuitive, the lower setting giving the louder result.
Just because something is at +4dB does not mean it will be quieter, there is gear that even at -10 it's VERY quiet...

Some think that JUST because something runs at +4 it's pro, not always..
Plus some gear has RCA's Ins/Outs but can have the same maximum output as some +4 gear.... That depends on the supply rail voltage..

If you are at a +4 level its best to keep it there if possible, going up and down and back up can add noise..
Old 5th August 2015
  #85
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Old thread, but a good one. And it pops up early in Google searches, so it is worth continuing.
EDIT: oops. I didn't see that this thread had an extra couple of pages. I blame Google. My post may be redundant.

One thing alluded to a couple of times here, but not discussed in any detail is that +4 is typically a balanced standard (XLR or 1/4"TRS), while -10 is typically unbalanced (RCA or 1/4" TS-mono or 1/4" TRS stereo with left on tip, right on ring, and ground on sleeve) . There are devices out there made to cross-convert balanced to unbalanced and vice versa, but you can usually do just fine by wiring your connectors up the right way. Of course, note that I said typically, and not always. There are exceptions.

Just to make certain people understand, balanced audio has a positive, a negative, and a ground, whereas unbalanced only has a positive and ground. So, if you are going from an balanced output signal to an unbalanced input, you will either leave the negative disconnected, or (more often) short it to the shield. Since a +4 dBu signal is balanced, this level is measured between positive and negative. When you use only the positive and shield, or short the negative, you are reducing the signal level by 6 dBu, and you need to remember that when anticipating your input level. So, if you wire up a typical +4 dBu balanced signal into a -10 dBV unbalanced input, you actually have only -2 dBu to work with. Further converting that for the reference scale, you actually have around -4.2 dBV. You'll want to run it a little low or pad the signal by about 6dB.

Going the other way, connecting an unbalanced -10 dBV into a balanced +4 dBu input, you have no negative to work with. So you connect the positive and the shield only and short the empty negative pin (XLR) or ring (TRS) to ground. The signal is translated to about -7.8 dBu going into your balanced connection. You'll want to crank it up around 12dB.

Or, you can use a device which converts these for you. But the main point I am trying to make, is that when you talk about the relationship between -10 and +4, you are typically not just talking about signal level, but also the difference between balanced and unbalanced audio. I have even seen some old audio boards where the "+4 / -10" switch was not just inserting a pad, but actually switching the input connectors from an XLR or TRS to a couple of RCA's on the board.
Old 6th August 2015
  #86
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Matt Nolan's Avatar
 

I'm not sure you've got this all correct.

Firstly, it is worth stressing that the type of connector and balanced or single-ended does not necessarily influence the nominal signal level. They are often correlated, but not always. Assumptions should not be made. With each piece of gear it is worth finding out what is actually going on. Read the manual.

Secondly, in a properly done transformer or electronically balanced output, the signal is not referenced to ground, so "shorting" the cold lead to ground doesn't "short" anything and you still have the full differential voltage between hot and cold - no loss of dBs. Only if the output is differentially driven will you get the shorting of which you speak, and the loss of 6dB. So, again, you really need to look at the specs / the manual to know what is really going on.

Likewise, for a transformer based input, connecting an unbalanced line in the way you suggest will not work. You need to connect the signal line to the hot input and the ground line to the cold input otherwise there isn't a closed circuit. Leave the "ground" connection - which is really a "sheild" or "screen" connection connected in the XLR or TRS at the transformer input end and have it floating at the preceding equipment output end then it can still work as an electrostatic sheild.

Also - pedantic - the signal drop when shorting one side of a differentially driven line is 6dB, not 6dBu. 6dB is a ratio. 6dBu is an absolute value.

Welcome to Gearslutz!
Matt.


Quote:
Originally Posted by Teamscottsmith View Post
Old thread, but a good one. And it pops up early in Google searches, so it is worth continuing.
EDIT: oops. I didn't see that this thread had an extra couple of pages. I blame Google. My post may be redundant.

One thing alluded to a couple of times here, but not discussed in any detail is that +4 is typically a balanced standard (XLR or 1/4"TRS), while -10 is typically unbalanced (RCA or 1/4" TS-mono or 1/4" TRS stereo with left on tip, right on ring, and ground on sleeve) . There are devices out there made to cross-convert balanced to unbalanced and vice versa, but you can usually do just fine by wiring your connectors up the right way. Of course, note that I said typically, and not always. There are exceptions.

Just to make certain people understand, balanced audio has a positive, a negative, and a ground, whereas unbalanced only has a positive and ground. So, if you are going from an balanced output signal to an unbalanced input, you will either leave the negative disconnected, or (more often) short it to the shield. Since a +4 dBu signal is balanced, this level is measured between positive and negative. When you use only the positive and shield, or short the negative, you are reducing the signal level by 6 dBu, and you need to remember that when anticipating your input level. So, if you wire up a typical +4 dBu balanced signal into a -10 dBV unbalanced input, you actually have only -2 dBu to work with. Further converting that for the reference scale, you actually have around -4.2 dBV. You'll want to run it a little low or pad the signal by about 6dB.

Going the other way, connecting an unbalanced -10 dBV into a balanced +4 dBu input, you have no negative to work with. So you connect the positive and the shield only and short the empty negative pin (XLR) or ring (TRS) to ground. The signal is translated to about -7.8 dBu going into your balanced connection. You'll want to crank it up around 12dB.

Or, you can use a device which converts these for you. But the main point I am trying to make, is that when you talk about the relationship between -10 and +4, you are typically not just talking about signal level, but also the difference between balanced and unbalanced audio. I have even seen some old audio boards where the "+4 / -10" switch was not just inserting a pad, but actually switching the input connectors from an XLR or TRS to a couple of RCA's on the board.
Old 6th August 2015
  #87
Lives for gear
 

Hi
Matt's explanation is of course correct but I would like to add that in the situation of an 'electronic balanced out', which DOES compensate for signal level, making it act like a transformer there IS an issue with the maximum signal level in that it will now 'clip' 6dB lower compared to when it is being connected to a balanced Input.
Again as always, READ THE MANUALS for ALL your gear.
Matt S
Old 6th August 2015
  #88
Gear Head
 

Guys very informative thread indeed! My set up is as follows MacPro Digital Out>TC BMC-2>Dynaudio BM5 MK3's.According the the Dyn's manual
Quote:
8. Level trim
Use this switch to match the sensitivity of the BM5 mkIII monitor to your source. High-output Source: If your source has a high output, set switch to the -10 position to reduce sensitivity by 10 dB.
Low-output source: If your source has a low output, set switch to the +4 position to gain 4 dB more sensitivity.
The TC manual states
Quote:
Impedance:< 100 Ohm
Max. Output Level:+13 dBu, -5 dBu DIM activated
Digital Gain:Off to +12 dB
So Based on the above the input switch on the Monitors should be set @-10 right? or am i completely missing the obvious here?
Old 6th August 2015
  #89
Lives for gear
 

Hi
My reading of this is that the manual is badly written!
It suggests that the switch is really a 10dB attenuator and NOT specifically a setting for '+4 or -10' dB.
Whatever, play some music so that you have a usual output level on main meters (-16dBFS or whatever) then set the monitor volume pot to about 3/4 rotation then select the switch to get a suitably loud level in your room. (usual gain staging techniques).
I have simplified my answer to make it brief but of course +4dBu to -10dBV is actually (almost) 12dB, making the switch labelling even more incorrect!
Matt S
Old 6th August 2015
  #90
Gear Head
 

@ Matt, actually the monitors does Not have a volume pot and the TC metering is a bit different to usual metering but i do get what you're saying so thanks for the comments or rather your input
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