• Registered: 2008-08-14
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Topic: "Proper" gain settings for mic pres on RME UCX for line level inputs

I have had an UCX 1 for a while now but until recently have not used the mic pre inputs (1 and 2). I only work with synths so I'm used to working with line level signals on inputs 3-8. All of my synths have unbalanced outputs so I set the reference level to -10 dBV and adjust the master volume on the synth as appropriate.

For inputs 1 and 2, I have a synth connected using TS cables. Since inputs 1 and 2 don't have a reference level setting in TotalMix, I'm a bit confused as to what I should be setting the Gain to in order to mimic -10 dBV. Thanks for any advice!

  • Registered: 2016-06-14
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Re: "Proper" gain settings for mic pres on RME UCX for line level inputs

Not sure -10dBV is the correct setting. Also when unbalanced, pro audio gear often is at +4dBu level.
Anyway, from the L/R stereo cable you could connect one plug to input 1 and the other to input 4, then set equal levels by ear (and level meter in Totalmix). As soon you have a matching signal, you can connect the plugs to inputs 1/2.

UCX - FF 400 - Babyface pro - Digiface USB - ADI-2 (original)
Mac mini M1 - Macbook pro - iPad Air2

3 Reply by ramses (edited by ramses 2023-09-29 06:38:43)

  • ramses
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Re: "Proper" gain settings for mic pres on RME UCX for line level inputs

The manual ch 19 contains details information about your UCX's inputs.

> I'm a bit confused as to what I should be setting the Gain to in order to mimic -10 dBV. Thanks for any advice!

There are different analog inputs for different purposes.
- Analog Line inputs with different ref levels that usually occur (consumer and different studio levels). They can be balanced or unbalanced. Often have a gain knob to be able to make finer adjustments to the sensitivity of the input up to around 9dB.

- Instrument and Mic inputs with gain settings, as fix ref levels, make no sense here. Pickups (active, passive, guitar, bass) and Mics (dynamic, ribbon, condenser) have such different output volumes that you need a possibility to adjust gain over a wider range. Additionally, Mic inputs deliver phantom power for condenser mics. Instrument inputs (aka Hi-Z) are for musical instruments such as electric guitars and bass guitars with magnetic pickups. Instrument inputs are equipped to handle signals with a higher impedance, and lower volume in comparison to line-level signals.

You can use Mic inputs as unbalanced line input, but you need to adjust the input sensitivity with a gain knob instead of switching reference levels and "fine adjusting" with digital gain over a smaller area.

BR Ramses - UFX III, 12Mic, XTC, ADI-2 Pro FS R BE, RayDAT, X10SRi-F, E5-1680v4, Win10Pro22H2, Cub14
  • Registered: 2016-06-14
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Re: "Proper" gain settings for mic pres on RME UCX for line level inputs

ramses wrote:

You can use Mic inputs as unbalanced line input, but you need to adjust the input sensitivity with a gain knob instead of switching reference levels and "fine adjusting" with digital gain over a smaller area.

That’s true. So, not to disagree, but as an addition: on some (RME) devices with combined mic/line inputs, there are more concrete level setting informations. For example in the Babyface pro (FS) manual, RME writes:
The Babyface Pro has two analog microphone inputs that can operate as line inputs with levels up to +19 dBu, when set to 0 dB gain and PAD active.
As far I understand it, on the UCX inputs 1/2 6.35mm ports, there is a fixed attenuation of 11dB and the lowest gain setting is a good point to start when looking for a matching line level.

UCX - FF 400 - Babyface pro - Digiface USB - ADI-2 (original)
Mac mini M1 - Macbook pro - iPad Air2
  • Registered: 2008-08-14
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Re: "Proper" gain settings for mic pres on RME UCX for line level inputs

Thank you both for the information and suggestions. So from my understanding inputs 5-8 on my UCX are simply less flexible, only for line level signals and you have a few options for adjusting for the type of signal. Inputs 1-4 are more flexible thanks to the Gain knob, allowing for the ability to more finely tune the gain due to the wide variety of signal types supported.

I'm evaluating which of my synths to use on inputs 1 and 2 as some seem to be noisier than others. oli77sch's suggestion of hooking one of the synth outputs to input 3 was really helpful though, with an init patch on my synths I could easily dial in the gain to match what I was getting for levels on input 3.

As for the level settings for my more modern synths, I have reached out to tech support for both Sequential and Moog earlier this month while dealing with a USB noise issue. Moog recommended the -10dBV setting for my Matriarch and keeping the master volume on the synth at 12 o'clock. Sequential said their synths run a hot -10dBV meaning in reality they are between -10dBV and +4dBU. So their suggestion was to use the -10dBV setting and keep the master volume on the synth at around 70%.

Lastly I have a Kurzweil K2000 which is really quiet at +4dBU and an Access Virus B that I know has unbalanced outputs but beyond that I'm not sure what setting they recommend for a setting.

6 Reply by ramses (edited by ramses 2023-09-30 08:42:29)

  • ramses
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Re: "Proper" gain settings for mic pres on RME UCX for line level inputs

Sorry, maybe I misunderstood you, but this sounds too negative. I initially didn't intend to delve further into this topic.

theoryzero wrote:

Thank you both for the information and suggestions. So from my understanding inputs 5-8 on my UCX are simply less flexible, only for line level signals and you have a few options for adjusting for the type of signal. Inputs 1-4 are more flexible thanks to the Gain knob, allowing for the ability to more finely tune the gain due to the wide variety of signal types supported.

But since you mentioned it that way, I wanted to bring up a few additional points for you to consider before you later assume (wrong) that some ports on your UCX are not well-equipped or something in that range.

Please bear in mind that the BBF Pro has a compact form factor with limited space for ports. Here, RME has just added a PAD function so that the port can support higher input levels, to make the few ports as flexible as possible.

Otherwise, ports on a device are designed in a way that you deem most useful for the construction and the user. The UCX has a larger form factor and provides the possibility for more ports. This enables offering the typical type and number of ports that are most beneficial to support many use cases.

Certainly, there are other design considerations, such as not overloading the ports with functions. Too many components and excessive complexity are also not always advantageous (more complex PCB layout, higher price, maybe also heat, ..). Finally, everything must fit seamlessly into 9.5" format.

BR Ramses - UFX III, 12Mic, XTC, ADI-2 Pro FS R BE, RayDAT, X10SRi-F, E5-1680v4, Win10Pro22H2, Cub14

7 Reply by oli77sch (edited by oli77sch 2023-09-30 09:15:15)

  • Registered: 2016-06-14
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Re: "Proper" gain settings for mic pres on RME UCX for line level inputs

ramses wrote:

Please bear in mind that the BBF Pro has a compact form factor with limited space for ports. Here, RME has just added a PAD function so that the port can support higher input levels, to make the few ports as flexible as possible.

Otherwise, ports on a device are designed in a way that you deem most useful for the construction and the user. The UCX has a larger form factor and provides the possibility for more ports. This enables offering the typical type and number of ports that are most beneficial to support many use cases.

The comparison came from my side. To avoid misunderstandings: my point wasn’t the units with its form factors and technical specs but the wording in the manuals.
In my opinion it’s way more clear and helpful (at least for users with less technical knowledge) in the manual of the BBFpro(FS). It’s simply 'gain at zero + pad on = line level input'. The explanation in the UCX manual is more complicated and maybe let some questions open.
«The two combo jacks also allow for the usage of mono and stereo TRS jacks. The TRS inputs have a fixed level attenuation of 11 dB. Based on the adjustable amplification from +0 dB up to +65 dB, the sensitivity is +21 dBu down to –44 dBu, referenced to full scale of the AD-converter. Therefore the TRS inputs are true full level Line inputs, and the unit can also be used as Line amplifier.»

UCX - FF 400 - Babyface pro - Digiface USB - ADI-2 (original)
Mac mini M1 - Macbook pro - iPad Air2

8 Reply by ramses (edited by ramses 2023-09-30 10:10:18)

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Re: "Proper" gain settings for mic pres on RME UCX for line level inputs

theoryzero wrote:

Thank you both for the information and suggestions. So from my understanding inputs 5-8 on my UCX are simply less flexible, only for line level signals and you have a few options for adjusting for the type of signal. Inputs 1-4 are more flexible thanks to the Gain knob, allowing for the ability to more finely tune the gain due to the wide variety of signal types supported.

I'm evaluating which of my synths to use on inputs 1 and 2 as some seem to be noisier than others. oli77sch's suggestion of hooking one of the synth outputs to input 3 was really helpful though, with an init patch on my synths I could easily dial in the gain to match what I was getting for levels on input 3.

As for the level settings for my more modern synths, I have reached out to tech support for both Sequential and Moog earlier this month while dealing with a USB noise issue. Moog recommended the -10dBV setting for my Matriarch and keeping the master volume on the synth at 12 o'clock. Sequential said their synths run a hot -10dBV meaning in reality they are between -10dBV and +4dBU. So their suggestion was to use the -10dBV setting and keep the master volume on the synth at around 70%.

Lastly I have a Kurzweil K2000 which is really quiet at +4dBU and an Access Virus B that I know has unbalanced outputs but beyond that I'm not sure what setting they recommend for a setting.

Pls read manual ch 19 "Analog Inputs" and compare this with the technical specs in chapter 38.1.

Then you will find out that all analog inputs can be used as line inputs without any issues.

Analog Inputs 5–8 ("Line") support three different reference levels (-10dBV, +4 dBu, LoGain).
This supports input levels up to 13 dBu (which is 9dBu more than +4 dBu studio level).
This gives you 9 dBu headroom (until reaching 0dBFS).
So, even your louder Synthesizer supporting +4 dBu studio level won't go over 0dBFS.
Recommendation: I would use the setting +4 dBu for a start and in particular for your synthesizers which support +4 dBu studio level.
For the devices with less output, select -10 dBV consumer level and then compare which combination of synthesizer's output level (in the range of 80-100%) and ref level setting works best. At the end, all devices should have the same input level with maybe 9dB headroom (peak signal, x dB lower than 0 dBFS).

Analog Inputs 3-4 ("Line/Inst") are, according to the manual, "identical to rear inputs 5-8 in all technical specifications". They are even more flexible "by offering several gain and impedance options, which make them the ideal receivers for both line and instrument signals". They offer
- additional digital gain of up to 12dB
- to be switched to "Hi-Z" to act as "Instrument Input" with the required a higher impedance for connecting guitar, bass, ...
But the basic message is, that there is no functional difference, you can use analog inputs 3/4 like analog inputs 5-8.

Analog Inputs 1/2 ("Mic/Line") can also be used as line input and supports signals up to +21 dBu.
The manual tells in ch 19.2 "[...] therefore the TRS Inputs are true full level Line inputs, and the unit can also be used as Line amplifier[...]". The only difference to the Line inputs 3-8 is, that you have to use the gain knob for fine-tuning the input level.

At the end of the day, everything boils down to the task to
- set those analog inputs which have reference level settings (3-8), to use either consumer (-10 dBV) or studio level (+4 dBu) so that your synthesizer's output can be operated between ~80-100% and that all devices produce about the same input level
- set the gain of analog inputs 1/2 so that it has about the same input level like the other devices

Maybe my summary helps you to understand, that you will have no degradation in quality no matter which input you choose, all analog inputs can be used as line inputs and support even hotter studio levels, so no fear that something could be overloaded.
TotalMix FX will finally support you, that all devices will have about the same input level with some headroom before the 0 dBFS mark.

BR Ramses - UFX III, 12Mic, XTC, ADI-2 Pro FS R BE, RayDAT, X10SRi-F, E5-1680v4, Win10Pro22H2, Cub14
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Re: "Proper" gain settings for mic pres on RME UCX for line level inputs

BR Ramses, thank you! I didn't intend for my comment to seem negative, I understand that any of the analog inputs are equally sufficient for my application using line level signals. I was just saying the inputs 1/2 and 3/4 are more flexible in that they can also accommodate signal types from other sources such as mic or instruments, as you confirmed in your summary.

I appreciate the help and I've decided to use inputs 1/2 for my synths that don't easily fall into the norm that -10 dBV or +4 dBU offers.

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Re: "Proper" gain settings for mic pres on RME UCX for line level inputs

I think this is a good idea.
An alternative might be to use
- the analog output of the synth and/or
- AN 3/4's digital gain
for fine adjustment.

BR Ramses - UFX III, 12Mic, XTC, ADI-2 Pro FS R BE, RayDAT, X10SRi-F, E5-1680v4, Win10Pro22H2, Cub14