Is it possible to check you have sufficient amplifier headroom with a umik-1?

[abdo123]

That tells you the max in a test condition, and if you are using the same source, running the test signal at full amplitude, and never adjust the gain volume knob) higher to compensate for what appears to be a quieter song, then it has merit. The op said they tested at the "volume they normally listen to". If that means volume knob position and they used the same signal source as for music and ran the test signal at 100% volume, then the test has merit. If there are difference in the signal chain gain and/or the volume was "ear-balled", then the test my not have reached the actual peak levels that would be in music.

except that REW defaults to -12 dBFS and you usually need more than 10 times the power for something between -3dBFS and 0 dBFS.

 

[Blumlein 88]

That tells you the max in a test condition, and if you are using the same source, running the test signal at full amplitude, and never adjust the gain volume knob) higher to compensate for what appears to be a quieter song, then it has merit. The op said they tested at the "volume they normally listen to". If that means volume knob position and they used the same signal source as for music and ran the test signal at 100% volume, then the test has merit. If there are difference in the signal chain gain and/or the volume was "ear-balled", then the test my not have reached the actual peak levels that would be in music.

I'm failing to see problem here. You set up the test parameters to match what you are trying to find out.

 

[Blumlein 88]

except that REW defaults to -12 dBFS and you usually need more than 10 times the power for something between -3dBFS and 0 dBFS.

You can change that setting.

 

[abdo123]

You can change that setting.

yeah which is why I brought it up, it's important to understand everything encompassing the test to trully figure out if you have enough power for your use.

 

[dorirod]

Does anyone know of a writeup/video that walks you through this process? I am curious to look at my speakers and amp as well.

 

[Razorhelm]

I had the REW sweep and tone set to 0dBFS and the volume on the amp set to 0db, i normally listen at -12db

 

[pjug]

I didn't know about the REW scope. That's just for sweeps? It would we great if real music SPL could be scoped in REW to see peak SPL. Can it do this?

 

[RayDunzl]

I didn't know about the REW scope. That's just for sweeps?

It shows the moving waveform of what the UMIK-1 picks up real-time.

It would we great if real music SPL could be scoped in REW to see peak SPL.

Peak (unweighted) SPL can be shown in the SPL meter or graphed with the associated logger.

 

[pjug]

It shows the moving waveform of what the UMIK-1 picks up real-time.



Peak (unweighted) SPL can be shown in the SPL meter or graphed with the associated logger.

I am not following where you have a waveform view. I see scope as an option after a sweep.

In SPL logger I see the peak, but is that a true peak? It seems low compared to corresponding voltage I have measured with a scope on speakers.

edit: maybe I am not clear on what I thought scope might be. A triggered fast capure where you can really see the waveform.

 

[RayDunzl]

UMIK-1 may clip before your amplifier unless you change UMIK-1's gain settings. That requires opening it and changing dip-switch positions, also calibration file needs sensitivity parameter change (for REW to show correct SPL).

The bottom of the main window gives an indication of the clipping level, which varies with the microphone volume gain setting.

Why it says uncalibrated would be a question for the software author, but it should give you some clue to the useful range.

 

[RayDunzl]

I am not following where you have a waveform view.

Start here:

Gives a window

Shows what the mic (or in this case, a channel on my Focusrite) is picking up right now.

Other functions, don't know.

---

Changed input to UMIK-1, similar waveform display, but the max spl indication no longer says "uncalibrated"

That's with this input level in "Preferences":

Change level:

Changes peak SPL that can be calculated by REW:

 

[RayDunzl]

In SPL logger I see the peak, but is that a true peak? It seems low compared to corresponding voltage I have measured with a scope on speakers.

Voltage to the speaker and Sound Pressure Level are related, of course.

Send 2.83 RMS volts sine to the speaker and see what SPL the speaker emits at one meter, Check the specs and see how that compares to the speaker's sensitivity rating.

On the SPL meter you will the chosen average and peak.

Peak will be 3dB higher than the average.

 

[TimoJ]

The bottom of the main window gives an indication of the clipping level, which varies with the microphone volume gain setting.

Why it says uncalibrated would be a question for the software author, but it should give you some clue to the useful range.

View attachment 133835

I think UMIK-1's internal amplifier (before A/D conversion) will clip before that and adjusting mic gain with computer's gain controls won't help.
Here is AVS thread about it:
https://www.avsforum.com/threads/massively-clipped-umik-1.1797489/

 

[RayDunzl]

Spec says:

Max SPL for 1% THD @ 1kHz133dB SPL @ 0dB analog gain setting

For home use that would seem to be acceptable.

Clap your hands in front of the mic and see where it maxes. I remember 130dB reported and don't remember flat tops.

I get to be wrong.

www.minidsp.com/images/documents/Product%20Brief%20-%20Umik.pdf

 

[Spkrdctr]

I guess smoke coming from the driver is too old school

That is a GREAT comment! I like old school sometimes. Audiophiles would call that "burn in". LOL

 

[pjug]

Start here:

View attachment 133836

Gives a window

View attachment 133837

Shows what the mic (or in this case, a channel on my Focusrite) is picking up right now.

Other functions, don't know.

---

Changed input to UMIK-1, similar waveform display, but the max spl indication no longer says "uncalibrated"

View attachment 133838

That's with this input level in "Preferences":

View attachment 133839


Change level:

View attachment 133840

Changes peak SPL that can be calculated by REW:

View attachment 133841

Ah, I don't have the scope option (using Mac OS version 5.19). I need to update or maybe grab a windows machine I guess. Good to know about this; I want it! Thanks for your help.

 

[audio2design]

Ah, I don't have the scope option (using Mac OS version 5.19). I need to update or maybe grab a windows machine I guess. Good to know about this; I want it! Thanks for your help.

If you have the HD space run Parallels.

 

[pjug]

If you have the HD space run Parallels.

Thanks, but shouldn't be necessary. I have another laptop I can use when I get around to messing with this.

 

[eddantes]

I think this is an excellent question for a science based forum like this. I simply want to echo an earlier comment that one can rather easily estimate power requirements by knowing speaker effciency, listening distance, and average preferred SPL.

Even easier than that - 200watts per channel is a realtively safe place to start when discussing clipping under average conditions, with average speakers (Obviously if you do your listening in an airplane hanger at a distance of 100 feet and your speakers are <80db efficient - then the rule of thumb does not apply).

These days - 200watts is not even a lot of money (though it can be).

 

[Spkrdctr]

Unless someone listens at very loud levels, there is no worry of clipping on any 200 watt/4ohm rated amp or receiver. If your speakers are 87db efficient or higher you would be good to go. Unless you are in a very large room listening at very loud levels. Audio folks constantly look for something to worry about. If you buy a good decent 200 watt/4ohm amp, most people will be all set. Of course this varies on trying to reproduce live volume levels and running full range mains without a sub. Lots of variables, but with a sub, 90% of the listeners will be fine.