Buy a cheap mic booster; actually reduce the noise floor?

[ef37a]

DC-Choppah, I would love to know the make and model of your mixer. interface and that valve pre amp?

Your, well reasoned explanation shows the basic fact that in any amplification chain, something will determine the clipping point. I am not surprised that it turns out to be the interface, for a couple of reasons.
1) Almost all AIs use a 'One Knob' gain control and we rarely get pads on them these days. With just one gain control the practical gain range is perhaps +10dB to +60dB and even with that range the setting of the control at the high gain end becomes difficult, i.e. the top end is very 'cramped'. Thus there has to be a trade off between maximum gain and headroom, most going for higher gain* Mixers on the other hand have effectively three levels of gain control. That around the mic pre amplifier, the channel fader which often gives another 10dB at max and another 10dB at the master fader. Thus, greater headroom can be 'dialed' in.

2) Interfaces often have lower voltage supply rails than mixers and external pre amps. Typically a modest mixer will run at +&- 15V maybe 17V. I have not measured inside any AIs but I doubt 'budget' devices run much above 2x 12 volts? "Bus" powered AIs could be even less.

Valves of course can have massively greater headroom than solid state equipment but I am rather surprised yours has such a good noise performance? Hence my curiosity!

*This, IMHO is as it should be because it allows the use of a dynamic microphone for vocal work although quiet V/O work might still be problematic especially with the likes of a 7b. Overload problems can be sorted quite cheaply with an external attenuator should the need arise.

Dave

[Hugh Robjohns]

When I tried to use an SM57 on my piano (instead of my usual condensers), I could not get my PFL up to the recommended level for the piano.

Yes. Insensitive mic, low level source, preamp with restricted gain range.

Then I added more gain at the interface to be able to hear the piano in the monitor (headphone). But now when a bass drum hits from across the room, the interface clips!

I'm not entirely clear what you're doing here -- is the bass drum miked and going through the desk (and with the channel gain aligned using the PFL method as you described), or is this ambient spill picked up by the SM57?

Either way, the problem is a lack of headroom in the interface because you've wound its input sensitivity up.

If it's acoustic spill, being picked up by the SM57, the most likely reason for the apparently excessive signal level is that the mic is in a resonant chamber formed by the piano and its lid that happens to over-emphasise the bass drum fundamental, and/or it's positioned in an anti-node of the room's standing waves that do the same thing.

[Sam Spoons]

[pedantry] PFL = "Pre Fade Listen" aka "Solo" [/pedantry] used when live mixing to listen to an individual channel or bus without affecting the main output. On many mixers it also has the useful benefit of sending the signal to a meter (rather than just the 'signal present' channel LED) for more resolution when setting the gain structure.

[Hugh Robjohns]

Good point well made.

Adding further to the pedantry... although many budget mixers rename PFL as Solo, on high-end mixers they are actually quite different things.

A high-end, professional studio mixer normally has three channel monitoring modes: PFL, AFL and SOLO (or SIP -- solo in place!).

PFL monitors the signal from just before the fader (pre-fade listen), so it ideal for optimising the gain structure through the first part of the channel, and also for checking a source before fading it up. On a mono channel, PFL is also mono, of course, but may be mono or stereo on a stereo channel, depending on the architecture of the desk.

AFL (after fade listen) monitors the signal somewhere after the fader's buffer amp (to make up the signal level lost through the fader), so allows checking of the signal's contribution to the mix bus. Often AFL is actually derived after the pan-pot, so reflects any panning decisions too and in that case AFL would be in stereo of course, from both mono and stereo channels.

And then there's SOLO or SIP -- sometimes also rightly known as 'Destructive Solo'. On a broadcast desk this mode is automatically disabled when the studio's red TX light goes on.

Whereas PFL and AFL are monitored via separate and dedicated PFL/AFL busses, and can be used without affecting the main mix output in any way, the Solo function actually leaves the Solo'd channel alone, but mutes every other channel (and usually their aux sends, too) not selected to be either Solo'd or 'Solo Safe'. And instead of the monitoring switching to the PFL/AFL bus, it stays on the main mix output. So this is 'destructive' in the sense that the mix bus output is changed, with only the Solo'd channel(s) remaining audible.

Typically, things like FX return channels would be selected as 'Solo Safe' -- meaning that they won't be muted along with everything else -- so that a Solo'd channel can be auditioned along with any effects its contributing to. Different desks have different arrangements to control whether channels are Solo'd exclusively, or if multiple channels can be Solo'd and added or removed, and also in how the solo-safe system works.

Obviously, since the Solo system hijacks the main stereo mix outputs of the console, it is a stereo monitoring mode, and includes the effects of both fader levels and panning.

Some Solo systems get even more clever, and include a 'Solo-in-Front' mode where, rather than muting everything else, they just turn everything else down a bit... so this allows you to hear the solo'd channel(s) but still in some context with everything else. The balance of solo'd channel to the rest is usually adjustable.

[The Elf]

Some Solo systems get even more clever, and include a 'Solo-in-Front' mode where, rather than muting everything else, they just turn everything else down a bit... so this allows you to hear the solo'd channel(s) but still in some context with everything else. The balance of solo'd channel to the rest is usually adjustable.

One of the features of Cubase I use most often. Steinberg call it 'Listen'.

[Kwackman]

Some Solo systems get even more clever, and include a 'Solo-in-Front' mode where, rather than muting everything else, they just turn everything else down a bit...

I've learnt something new!

One of the features of Cubase I use most often. Steinberg call it 'Listen'.

Correction - I've learnt 2 new things!
Off to check out the Cubase manual.....

[The Elf]

One of the features of Cubase I use most often. Steinberg call it 'Listen'.

Correction - I've learnt 2 new things!
Off to check out the Cubase manual.....

I think you need to be using Control Room - but everyone should be using Control Room...

[Drew Stephenson]

Just to keep Desmond happy, it's also available in Reaper.

[CS70]

It'd be hard to find a DAW that does not have solo dimming?

[DC-Choppah]

DC-Choppah, I would love to know the make and model of your mixer. interface and that valve pre amp?

Mixer is Yamaha MG16XU: https://usa.yamaha.com/products/proaudi ... index.html

I also had the same issue with my old VLZ Mackie mixer (1202VLZ)

The 8 bus outputs from the Yamaha mixer go to the M-Audio Ultra 8r interface: https://www.manualslib.com/manual/45447 ... ra-8r.html

The valve preamp is: https://www.behringer.com/product.html?modelCode=P0CCZ

[DC-Choppah]

I'm not entirely clear what you're doing here -- is the bass drum miked and going through the desk (and with the channel gain aligned using the PFL method as you described), or is this ambient spill picked up by the SM57?

Either way, the problem is a lack of headroom in the interface because you've wound its input sensitivity up.

If it's acoustic spill, being picked up by the SM57, the most likely reason for the apparently excessive signal level is that the mic is in a resonant chamber formed by the piano and its lid that happens to over-emphasise the bass drum fundamental, and/or it's positioned in an anti-node of the room's standing waves that do the same thing.

Ambient spill picked up by the SM57 in the piano. That was the only mic on.

I have a much better piano mic setup now thanks to you guys
Thank you kindly to Hugh who patiently worked through all of my other piano lid issues on a previous thread! Getting away from the lid sound was a huge improvement for me. And I get many comments from folks who want me to make piano tracks for them cause they dig my sound!

But I still like to try the SM57 style mics to hear how they sound on other stuff where the mic is not right up close, and sometimes it is just right! The extra preamp gain is needed to avoid these kinds of dynamic range problems with my system. I just want to get a proper level (via PFL procedure), be able to hear it in the headphone even though I am in the same room, and not clip! We are calling that 'head room' - being able to absorb big stuff without clipping.

[Hugh Robjohns]

We are calling that 'head room' - being able to absorb big stuff without clipping.

Yep... Naturally, there are practical limits to how much headroom can be employed in any given situation, and it's always about optimising the gain structure.

If your mic/source combination only generates a low output level, turning up the interface sensitivity is definitely the wrong solution -- you will be compromising the noise floor and reducing the headroom for other sources. A cascade preamp for that specific mic is a much better, more practical solution with much better technical performance too.