Not another +4db thread - but more specific to level behavior.

[wavestar]

Hello

My question is in the paragraph below, but to better understand the question: I'll just say that, I have an RME UCX II .
The RME has, (for the physical inputs/outputs) sensitivity/refrence level settings of:

• +13db and +19db on the input side
• +4db +13db and +19db on the output side

RME's main reason for not adding a +4db reference setting on the input side (according to a tech at the US plant) was that, "People were overloading their DAW meters".


here is my question:
When you have a piece of gear with a witch on the back for -10/+4 and it's switched to +4, does this mean that the unit is putting out +4 line level without any gain changes? In other words an FX unit that is set to +4, comes into your audio interface at approximately 1.228 volts? Or is +4 going to be MAX output level if the unit's FX output knob were turned up to full/wet? I never understood if the +4 switch on the back of these units were just a sensitivity thing, or if it sets the raw RMS or common output at that 1.228 voltage.

If that's the case, then I would think +4 output of an external unit would put a digital meter in a DAW at almost 0dbfs giving you no headroom. I'm guessing in the old days when outboard gear was +4, it was ok to be at 0VU because you still have plenty of head room, but with digital today, company's have chosen NOT to use +4 reference levels to prevent overloading? None of this still makes scene to me. One website says that dbv and dbu are identical, "To quickly convert between dBu and dBV note that dBu is always equal to dBV plus 2.21." https://support.biamp.com/General/Audio/Gain_structure:_input_and_output_levels.
How is it identical if you have to add 2.21v.

Thanks

 

[LazerBeakShiek]

Hello

My question is in the paragraph below, but to better understand the question: I'll just say that, I have an RME UCX II .
The RME has, (for the physical inputs/outputs) sensitivity/refrence level settings of:

• +13db and +19db on the input side
• +4db +13db and +19db on the output side

RME's main reason for not adding a +4db reference setting on the input side (according to a tech at the US plant) was that, "People were overloading their DAW meters".


here is my question:
When you have a piece of gear with a witch on the back for -10/+4 and it's switched to +4, does this mean that the unit is putting out +4 line level without any gain changes? In other words an FX unit that is set to +4, comes into your audio interface at approximately 1.228 volts?

It means you have selected +4 line level range operations. Something TS going to a guitar amp would be set for -10. +4 is mixer line level, XLR/TRS.

Or is +4 going to be MAX output level if the unit's FX output knob were turned up to full/wet? I never understood if the +4 switch on the back of these units were just a sensitivity thing, or if it sets the raw RMS or common output at that 1.228 voltage.

what. Mix wet/dry , is not -10 or +4 level.

If that's the case, then I would think +4 output of an external unit would put a digital meter in a DAW at almost 0dbfs giving you no headroom.

Theres headroom. whats your rated nominal output level?

I'm guessing in the old days when outboard gear was +4, it was ok to be at 0VU because you still have plenty of head room,

what

Thanks

uh-huh

 

[wavestar]

The specs say: the Maximum Output Level At 990 Output 75 Ohm load +24

The John Hardy Company M-1 Personal Mic Preamp

But in you're first response to me, you're talking about +4 line level range operations. That's on my interface. I'm not asking about my Input/Output sensitivity settings. I only posted that example so you understood that RME removed the +4 reference level to basically dummy proof level clipping issue. I'm aware of how the reference level setting work to a large extent.

On your second to last response, I was asking about old outboard gear to triangulate and understand the bigger picture.
What I'm asking is: When you're bringing in external +4 equipment into your DAW, What's is the voltage that goes out and comes into the input side of the Interface/DAW?
I'm asking because I don't fully understand the reference differences. It seems like +4 from the external gear would clip your digital meters in the DAW. And that's why I was saying that +4 might have been from the days of when things were mostly analog. But again, I think that's why RME maybe removed the +4 reference on the input side and went with +13 and +19 which was capable of excepting a hotter signal.

 

[bouldersoundguy]

Those numbers are probably nominal levels, not peak levels. With most converters, +4 dBu translates to -18 dBFS. In that case, a +22 dBu signal would hit 0 dBFS. If the converter translates +4 dBu to -20 dBFS, it would take a +24 dBu signal to hit 0 dBFS. Typically: 0 dBVU = +4 dBu = -18 dBFS.

But people are dumb and think they need to "fill up" the full scale in the DAW. Making +13 dBu translate to -18 dBFS forces another 9 dB of headroom into the chain. Unfortunately, that seems like it would make the nominal level of a properly set analog signal land around -27 dBFS or or make the engineer run their analog signals 9 dB above optimal to get them around -18 dBFS. On the other hand, I've often had a problem with some high end preamps producing really hot signal with louder sources, so it might help with those.

 

[wavestar]

I thought 0dBu = -18 dBFS / +4dBu = 15dBFS, or something like that. But what you said makes sense. That explains why it takes so much gain to get my levels up. RME chose to leave out the +4 on the input side of their Fireface UCX II and go with +13 & +19 reference levels which expect even hotter signals. But they did give you a digital gain option for those who don't have the extra gain I guess. But if they did have a +4 reference, then I guess my signal would be -15 which would be a much better match right from the start. I'm just looking for conformation that I'm understanding all this correct in my head.

In any case, this subject can be confusing to new guys like me who were not playing with this stuff in the analog age. With digital, now there's so many new terms and references differences, and everyone explains it different, it adds a lot of ambiguity to those trying to get grips with it. I've been reading different sites regarding line levels for the last few months. Its tricky tying it all together. I know enough to do what I'm doing, but I'm just interested to learn more at this point.

By the way, I was not aware of the term Normal/zero-reference till you and Lazer mentioned it.

Nominal Level - inSync

Nominal implies that something is according to plan, with only insignificant differences. A nominal level implies... Read more »

www.sweetwater.com

Zero Reference - inSync

In audio, a standard signal level that is defined as the nominal operating level for the... Read more »

www.sweetwater.com

 

[rob aylestone]

I've always followed this chart when I try to compare levels - which I rarely do because it fries your brain.

The page it was on is quite worth reading - sorry, but it's another link to Dave's favourite site Sound on Sound.
this page

 

[jamesperrett]

I thought 0dBu = -18 dBFS / +4dBu = 15dBFS, or something like that. ... RME chose to leave out the +4 on the input side of their Fireface UCX II and go with +13 & +19 reference levels which expect even hotter signals.

I think you are completely confusing what the different numbers mean.

To start with a common level would be 0dBVU = -18dBFS = +4dBu. 0dBVU is your reference level which might exist on a meter on a piece of gear but it doesn't represent a voltage level or a digital level. You decide how you want to translate 0dBVU and, as you say, a common voltage level is +4dBu but it could also be -10dBV or something different. It could also, as you say, translate to -18dBFS but some people go as high as -14dBFS (though I find this too high for comfort) while others go as low as -24dBFS.

Those RME numbers are not reference levels - they are the maximum levels that the device will accept. The input with the +19dBu maximum level will just about handle a standard +4dBu output although I'd prefer to feed it with a bit less. Looking at the specs only line inputs 1 and 2 are capable of handling full professional levels with a maximum level of +24dBu. I can understand the confusion because RME talk about their full scale levels in the same way that most people would talk about reference levels.

I'd also echo Rob's suggestion to read the SOS link - Hugh Robjohns is always good at explaining these things.

 

[wavestar]

I think you are completely confusing what the different numbers mean.

To start with a common level would be 0dBVU = -18dBFS = +4dBu. 0dBVU is your reference level which might exist on a meter on a piece of gear but it doesn't represent a voltage level or a digital level. You decide how you want to translate 0dBVU and, as you say, a common voltage level is +4dBu but it could also be -10dBV or something different. It could also, as you say, translate to -18dBFS but some people go as high as -14dBFS (though I find this too high for comfort) while others go as low as -24dBFS.

Those RME numbers are not reference levels - they are the maximum levels that the device will accept. The input with the +19dBu maximum level will just about handle a standard +4dBu output although I'd prefer to feed it with a bit less. Looking at the specs only line inputs 1 and 2 are capable of handling full professional levels with a maximum level of +24dBu. I can understand the confusion because RME talk about their full scale levels in the same way that most people would talk about reference levels.

I'd also echo Rob's suggestion to read the SOS link - Hugh Robjohns is always good at explaining these things.

I actuality do understand what you explained in the first paragraph. A common level can be anything.
I know 0dBVU is a reference only. A wrong word used, and things can go way out of wack with these kinds of topics, sorry about that. I meant to imply that if you supplied a voltage to bring a meter up to 0dBVU (analog), that same voltage would equate to -18dbfs on a digital meter in a DAW for example. Although I'm sure there's something I'm missing because this stuff is never that easy. 0dBVU which is analog equates to about -18dbfs on a digital meter. Is that not right?

In your second paragraph: I was referring to the (+13/+19 RME input settings) as reference levels because the manual refers to them as that on page 40 (see attachment). Actually I reversed it. I said: Reference Level, I should have said Level Reference. Level Reference is directed towards the chart itself, and Reference Level is the setting of the internal sensitivity switch.
Regardless, would it be safe to say that 'they set the sensitivity on the inputs of the RME to get a better match of signal - to the output level of your external gear? If I'm wrong sorry. That is just how I understood it. I think all this is easy when it clicks, but it's really difficult to talk about because there's so many moving parts if you are playing both in the digital and analog arenas.

I'll check out Hugh Robjohns. But once they start getting into math logs, square root stuff, I'm lost.
This guy was great at first, then he started getting into the math and I was lost
Decibels (dB) In Audio | The 5 Things You NEED To Know

@rob aylestone
I've been to that page, good chart, crazy page.

EDIT.
@jamesperrett
I just noticed where you said, "I can understand the confusion because RME talk about their full scale levels in the same way that most people would talk about reference levels."
Just curious. How did you know that they were Max levels? I would not have known from just reading their manual.

 

[ashcat_lt]

0dBVU which is analog equates to about -18dbfs on a digital meter. Is that not right?

Yes, that is not right. 0dbVU can be anything it wants. Often it is +4dbu. -18dbFS can be anything it wants. Less often, it is +4dbu. In plugins and DAWS, often 0dbVU = -18dbFS, but at that point nobody cares about actual voltages or dbu.

 

[wavestar]

I said 0dBVU equates to -18dbfs. I'm talking about a voltage at 0dBVU would translate to -18 in a digital system. I'm not saying 0dBVU is locked to that reference.
I care about actual voltages because I'm trying to understand it. it's difficult to tie all these references together, because I'm coming at it from a digital frame of mind, but a lot of these sites are talking about analog gear, but not always drawing good distinctions for people new to that world. I don't want to be like these kids at Guitar Center that don't know their A from a hole. The other day, some guy at GS told me, the max length of an XLR is about 15 feet before it starts to loses signal..lol. I don't want to be that guy.

I saw something online about calibrating UV's and that took me on another crazy ride. Loosing my mind.

 

[bouldersoundguy]

The dBVU and dBFS scales are not voltages although they often correlate to a dBu value, which is a specific voltage. Well, in a given device, dBVU might be a voltage, but in a different device, 0 dBVU could be some other voltage. More or less the same thing with dBFS. Often -18 dBFS correlates to +4 dBu, but it doesn't have to. Depending on the converter design, +4 dBu can be anything with -20 to -12 dBFS. Back in the days of 16 bit or even lower (I think my Boss SE-50 and SE-70 effects processors were 12 bit), it was pretty routine to run a lot closer to digital 0.

**************************************

I just had a look at the manual. Those values, +19 and +13 (depending on the sensitivity switch), are the analog levels that will give you 0 dBFS with the input gain set to 0 dB (Line Inputs 3-8). If you run the gain up to +12, +1 dBu will produce 0 dBFS (at the +13 dBu sensitivity setting). I would keep the switch at the +19 position, which is still a little hot. Then a +4 dBu will land right around -15 dBFS, so maybe run the analog just a little low to make your digital levels more like -18 dBFS.

Line Inputs 1 and 2 can take the full +24 dBu, which means +4 dBu gives you a -20 dBFS level. All of which I think jamesperrett said with slightly different phrasing.

 

[rob aylestone]

Years back, when you specified a unit in dB you had to qualify it by reference to something. It’s a meaningless term without the qualifier. Unless they include the reference voltage, it’s like having a volume control numbered 1 to 10 and telling people to turn it up from 3 to 6, without mentioning it’s a 12KW PA system connected, not a sound bar on your TV. The different terms and scales in use are just pointless without a manufacturer adding in the critical data. In the sixties and seventies, they’d bang on about 0.775v or 1.4V or a lower level, 300mV and equipment would be labelled up so the .775V read 0dB on a meter. Now with 32 bit digital audio, we seem to be needing a scale to cope with these expanded dynamic ranges. I wonder what a tone, recorded to digital maximum actually measures on a Volt meter. I bet it’s different on everything.

 

[wavestar]

Good stuff guys. I'm saving all this to my notes.
@bouldersoundguy
I think my TotalMix channels are set to +19, and then there is digital gain up to 12 more db, but my John Hardy M1 has a tone of gain so I don't even use their gain. I appreciate you taking a look at that manual.

@rob aylestone
That was a good read and look into the past. I didn't think of it that way, I know that's what ashcat_lt meant also a few posts up. Didn't realize how manufactures deviated with regard to what a reference actually puts out in power.

This Marcus Hutsell guy brakes down the phone company logic behind the markings after db in this first video. I'm taking in what you guys said also. Just trying to grab pieces from everywhere. I'm reading this SOS atm also.


What does Zero dB actually mean

Mic Level vs. Line Level Audio, what's the difference?

Audio 101 - Gain Structure and Noise - Part 01

Audio 101 - Gain Structure and Noise - Part 2

 

[rob aylestone]

dBW, dBV and similar make sense - but then you get dBFS - but what full scale? A scale that finishes at 0, or 4, or what? That's the trouble with using any dB scale system, it always has to be linked to something else - and that something may or may not be accurate or relevant. That is why I liked the BBC always using PPM meters instead of VU meters - which had the same markings with 0 indicating red (bad) when everyone knew a handclap would always read wrong, but an aaaaaaaaaaaaah would read right - stupid system!

PPMs, in a 600 Ohm circuit would all read the same, if they were on a tape machine, mixer or broadcast console.

The BBC 1952 explanation of BUs, dB and PPM levels makes interesting reading and while a bit technical in places explains how even back then, it was confusing. At one point - it mentions that PPM 6 is (currently) 0dBU the word currently being a give away that standardisation even 70 years ago was causing trouble!

BBC 1052 document

 

[ecc83]

The confusion about levels and reference voltages and dBs of all sorts is, IMHO a direct result of the growth of audio recording gear "for the masses".

If we forget about 'digital' for a moment and consider a 'pro' mixer, that will almost certainly have an 'operating level' of +4dBu and any VU meters would likely be calibrated such that +4dBu was 0 VU. However the internal electronics would have a headroom of at least 20dB. Any external equipment connected such as a pro tape machine or a hardware graphic or compressor would have a similar OP level and headroom (it would also likely have balanced ins and outs)
Back in the day, the early digital recorders would be setup to operate at the same levels.

Enter the home recording scene. Built as they are to a price, interfaces, especially 'bus' powered interfaces could not handle such levels. Now, the SENSIBLE thing to do would have been to say "OK, can't do +24dBu so we will run to a STANDARD OP L of -10dBV . But "they" didn't and so we have this mess of different interfaces with OPs all over the shop.

Add to the cluster**** the fact that newby Joe want to see -6dBFS when he just whispers into his SM58 or drops a feather on a string of his Strat and a lot of kit has too much gain. One bad effect of that is active monitors. They often are made with more gain than they need and are thus noisy.


Glad to see someone else linking SoS! I get a bit cheesed of with the flack!

Dave.

 

[wavestar]

I hear you.
I had my recording engineer friend tear out the amps of my Event ASP 6's years ago. I run the speakers though a crown 1002 Xti.
This is my setup here, and here with the speakers.
It's pretty small, but It's just me. For the mics being in the low price range they are, I've been blown away from some of the parts I've done just experimenting.
I use two oktava mk-012 on acoustics, they sound great. I feel like I haven't even touched the surface just with what Logic Pro 10 comes with. I use the external T.C electronics because the reverbs sound amazing for that price range. And the T.C comes in via Spdif only. I've been pretty lucky, I don't hear any busing or noise in my recordings. My cables are mostly the elite live wire but I do have some mogami for short runs in the back. I wish they were all mogami, but they are so damn expensive. I don't use the patch bay, I just don't know where to put it so I use it as a blank space..lol

 

[rob aylestone]

I don't think I have ever used any cable apart from either special offers or stuff that has mechanical toughness as a selling point. Balanced audio cable used to be Canford HST, and most of it the purple colour because it made spotting visiting crews stealing it easier to spot. Then it got too expensive and I swapped to Thomann's own brand - also in purple, but a different shade! Speaker cable will probably be rubber sheathed 4 core H07 4mm or 2.5mm. Absolutely not any cool cable - I got bitten a long time back when I spent a fortune on a branded cable for an analogue snake - 24 core and the damn stuff slowly coiled itself into a mess that refuses to lay flat or stretch out. Since then, I want tough, cost effective cable, which means no Mogowi or similar, unless it was VERY cheap, which it never is. Canare cable also used to be on my list, and for a while I used conductive plastic screened mic cable with Neutrik IDC connectors and found them very good and no need for a soldering iron - handy 40ft up in a cherry picker.

I always advocated Neutrik connectors, but again, price led me to china, where I've found some very decent XLR types, that solder easily and have excellent cable clamps. Different look to Neutrik, but not one failure and the plastic is iron proof like the Neutriks.

 

[LazerBeakShiek]

Whose got the most...cable?


wheres my cable box pic.

 

[jamesperrett]

I actuality do understand what you explained in the first paragraph. A common level can be anything.
I know 0dBVU is a reference only. A wrong word used, and things can go way out of wack with these kinds of topics, sorry about that. I meant to imply that if you supplied a voltage to bring a meter up to 0dBVU (analog), that same voltage would equate to -18dbfs on a digital meter in a DAW for example. Although I'm sure there's something I'm missing because this stuff is never that easy. 0dBVU which is analog equates to about -18dbfs on a digital meter. Is that not right?

@jamesperrett
I just noticed where you said, "I can understand the confusion because RME talk about their full scale levels in the same way that most people would talk about reference levels."
Just curious. How did you know that they were Max levels? I would not have known from just reading their manual.

As you say - use a wrong word and things can go very strange. That's why you were confused in the first place - RME weren't using the word "reference" correctly (or at least not as we use it in the English speaking recording world). It was obvious from the table you've linked to where everything is related to 0dBFS rather than what I would call a reference level.

When we start talking levels, correct terminology is vital. 0dBVU can be anything - analogue voltage, a reference fluxivity or a digital number. It is just a name for something that is commonly used as a reference. If your analogue level refers to a voltage you would normally use dBu or dBV. In some circumstances you can relate dBVU directly to dBFS but there is often an analogue voltage involved so you could end up with something strange if you ignore the analogue voltage part. While I set things up so that an 0dBVU tone on tape is -18dBFS, this is by no means universal so you need to find out what levels your gear uses and what are expected to deliver.

As an example, I transfer old studio tapes and these often have test tones on them. Different studios will use different magnetic flux levels for 0dBVU - sometimes this is obvious from the tape box but sometimes they may have used a dodgy test tape and the levels are a few dB off from where they say they should be. If these tapes use Dolby A noise reduction, this is a big issue because Dolby A requires the record and playback levels to be exactly matched for it to work properly. So I have to make sure that the level sent to the decoder has been properly adjusted to compensate for any variations in level. Usually this is fairly easy because the decoder has a meter and most Dolby tapes have a Dolby tone on them but occasionally I come across a tape with no Dolby tone so the Dolby level has to be calculated (and maybe tweaked by ear).

One other tip - ignore much of what you read on GS. Most of the knowledgeable posters (at least in my field) moved elsewhere many years ago.

 

[wavestar]

@ rob aylestone
Ya, I don't go overboard on cables. I always thought that the whole point in an XLR was to cancel out noise. And I think any decent or even low end XLR can do that. But I seen a video of this guy testing poorly isolated cables. Some of them did pick up some low noise which could be amplified if you had enough channels running, but the bigger issue was EMI changing the actual sound of the signal. I don't mind dropping some cash on some good cables since I don't need much for my tittle setup.
I keep my transformers hidden under the rack unit on a ceramic dish plate from the kitchen to prevent it from sitting on the carpet to limit a fire. This keeps them away from my cables. I'm not sure if the EMI gets though the wood on the bottom of the case, it's pretty thick with the wheel tray attached to the bottom as well.

My problem is, I worry that my cat will chew my cords. Although she's been good, she's never chewed my stuff. The females are usually good. I just hope she doesn't see me handling them and start thinking they're chewing toys.



@jamesperrett
Great info James. As crazy as it sounds, the last day or two I've actually taken screenshots of your posts I keep in a folder so I can refer back to them. I was actually reading something the other day about test tones and how in most cases, all devices were +4 with the older equipment so when you sent a test tone it was usually the same signal level. On a side note: I don't have anything other than my mic pre coming in. When I record, whet I've been doing is, I'm just using the gain knob on my mic pre to send a signal into my interface. Then from there I monitor the input level in logic pro so that I'm seeing about -6 or -8dbu on the meters. Unless there will be more then 5 tracks then I might shoot lower for -10. I also monitor my outputs in logic to see the combined signals from all the tracks. That's pretty much it.



LazerBeakShiek
That's about the extra cables I have. None of them had the correct connector ends when I got my Fireface, so I had to buy almost everything again.

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