Subwoofer level using Umik-1

[Thomas Larsen]

Hi - just bought the minidsp 2x4hd and had fun the whole day. Also have the Umik-1 (the 18 db version). Now I have a super flat response. I wanted to calibrate levels using this Umik and went for pink and white noise speaker calib -30 dbfs that should be 75 db target level. All fine but what about sub calib. ? Also -30 dbfs but 75 db or 85 db (the famous 10 db boost). Do REW compensate for it so all is 75 db ?
Other question - went for 9 db individual boost and 10 db boost overall - is that dangerous for my sub ? I never play insane loud. Know that Audyssey boost up to 9 db.
Happy Easter
Regards Thomas

 

[Wayne A. Pflughaupt]

Other question - went for 9 db individual boost and 10 db boost overall -

I have no idea what “individual boost” means

- is that dangerous for my sub ?

Impossible to say knowing nothing about your sub.

Regards,
Wayne

 

[Thomas Larsen]

Hi
the individual boost / overall boost is in the EQ section under filter options.Where you make filters for your MiniDSP and save the file. My sub is an older PSA V1800 sub. So far I did not hear anything bad - made one config for as flat as possible and then another one with room curve - 100 hz to 30 hz 0 db to 8 db (as seen elsewhere). All this works fine. Only place where I'm in doubt is the how to calibrate SPL levels using UMIK-1. Think I did it wrong - one thing is speaker cal and sub cal and -30 dbfs - but I was using the aux output from AV and sub output was hdmi 4. Reading the step by step guide (REW 101 -Rev 5.46 page 111) - it states to change to stereo on your AV and then go through the different outputs / hdmi's. Maybe in this way it outputs only from xover and down to sub = 75 db whereas if aux and hdmi 4 then it's the LFE channel with the +10 db i.e. then 85 db. Wonder how accurate the Umik-1 is compared to the Radio shack ?
Only one way forward - experiment and learn !

Regards Thomas

 

[Wayne A. Pflughaupt]

As long as you aren’t hearing rude noises from your sub, you’re good to go. No worries.

Re the SPL meter, with the UMIK’s sensitivity spec plugged into REW, for all practical purposes you have a reference quality, laboratory-grade Class 0 meter. Look up the price for one of those.

Can help with the “how to.” I’m using an old version or REW with an old computer that doesn’t have HDMI outputs.

Regards,
Wayne

 

[John Mulcahy]

Overall boost can be problematic, as dips are often very location-dependent so applying boost to fill a dip at the measurement position can create peaks when measured at even slightly different positions. Safest is to keep the overall boost value very low or zero, if you use overall boost measure at a few positions to see what effect your EQ is having.

 

[Thomas Larsen]

Hi
hmm just learned that I have set it up wrong . My umik-1 is the 18 db gain version. I followed the "Jerry" guide doc and here it tells you to set windows 10 mic level to 81 % / 9.9 +. But he is using the 12 db version of the mic. Some other place I found someone else have the 18 db version and here John M. tells the guy to set it to 0.0 db = 52 % (win 8). 0.0 db is also 52 % on my windows 10. So that could very well be the reason why my level meassurements are way off. From minidsp site - I can see from their guide using hdmi see that they use 18 db version - but in meassurement and spl meter they use -20 db and not -12 db as seen elsewhere. Easy to get confused here - but at least I'm not scared - think this is kind of fun.

 

[John Mulcahy]

The mic's internal gain doesn't matter, it is taken into account in the cal file sensitivity figure. The volume setting doesn't much matter either, other than a risk of clipping at high volumes if it is set very high. REW takes the volume setting into account - provided the UMIK is selected as the input device and the input and the cal file is loaded.

 

[Thomas Larsen]

hmm 90 deg. cal file loaded but I did get some clipping with the +9.9 db setting and meassurement with -12 dbfs. Will try to play with it at 0.0 db and then pick a recording level that kind of matches my receivers output level like 0.0 should be 85 if I pick -20 right ?! Only way forward is to try, try and learn.