Wow! This is not right!

[Timebandit2]

Hello there

Just moved rooms and trying out different speakers in my studio and i'm getting these readings. before and after putting in my GIK panels and absorbers.

These particular speakers go down to about 40, theyre Presonus Sceptres horn loaded concentric. There's no calibration on the PC input in this istance as im using a small analog mixer connecetd via USB for convinience, the only other available inputs to the PC are 16 channels of adat optical or TDIF.

For some reasons there's no roll offs any more as the bass should fall away and the high end looks like its going on a journey with Elon Musk!

It Does't seem natural, it looks like it's being calibrated for a sub but its not, I must have done something odd in the preferences, or other settings and cant see what it is as REW is not something I use every day!

If any one can help i'd very much appreciate it.

Thanks in advance!

 

[sam_adams]

Looks like you were measuring a loopback or monitor input along with some signal from the mic.

 

[Timebandit2]

Thanks for your observation. As mentioned there was no loop back due to the nature of the interface. The mic can, and has gone into feed back at high levels so once that occured its been been operating at a lower levels that REW is happy with.

It must be something ive done in REW preferences. I'll have a look with your suggestion. I'll also try with a pair of event 20/20 BAS. a bit over the top for this room, which 16.6 long, 11.6 wide and 8' 6" to celing. I'm hoping somewone will look at the mdat file and see if there are any areas in there whic need to be adjusted. Ive asked GIK for help and they've responded but mot really with amy solid suggestion I can fix this up with.

Sa, anyone brace enough to down load the mDat file to have a look...forever grateful for this forum!

 

[John Mulcahy]

The mic can, and has gone into feed back at high levels

That means there must be some monitoring path, otherwise where does the feedback come from? Reducing the level just masks the problem, it doesn't fix it.

You are measuring the R channel, is that the one the mic is plugged into?

 

[Timebandit2]

That means there must be some monitoring path, otherwise where does the feedback come from? Reducing the level just masks the problem, it doesn't fix it.

You are measuring the R channel, is that the one the mic is plugged into?

I Havent used REW for a few years and I foundd the online walkthroughs were very confusing as everyone is using their own bespoke hardware though I man

 

[Timebandit2]

Thanks for your replies, I was getting confused as the little mixer only has a simple pan contro and no drivers of it's own and I was getting into a muddle with the USB Audio Codec 1 and USB Audio Codec 2 on the Java drivers and started to crash which is a vewry rare occurance on window 10 I must say.

I uninstalled REW, got the new 64 bit installer for REW and fresh install of ASIO4all and been using the generator tab to determine channels and so far all is good apart from one annoying liitle thing... i've calibrated my DAW software and speakers before running rew and obviously calibrated everything to REW's SPL meter but when I switch the generator tabsdo the right channel, a box pops up on the screen and tells me the volume is very low and that i should raise it and recalibrate REW again!

If I close REW down and run the DAW, everything is balanced perfectly across the DAW's test generator/mixer, the soundcards adat channels and the avid controller out to the speakers and shows prefectly on the iPads meter at 85db's all across the whole system, so thats got me scratching my head!

I'll try again tomorrow but its been repeated on every measurement ive taken tonight, dont know if anyone else can reproduce that...?

 

[John Mulcahy]

A screenshot of the message would be helpful. If the highest input level during measurement is below -40 dBFS (for an analog mic) a warning is shown to advise increasing the input volume or the test level. Input volume is usually the one to adjust, but the SPL calibration depends on the input volume so if it is altered SPL calibration needs to be redone to show correct levels.

 

[Timebandit2]

Thanks for your time, heres some screen shots starting from scratch this evening for left, right and center positions. sorry for some screen shots, had to take some on phone as active window kept dissapearing when screenshot was taken.

1: Balancing speaker through daw, confirmed on phone/iPad and mixer at 85db
2: Levels set in REW 75db
3: Measuring left channel, OK
4: Measuring right channel - Error pop up to low and too loud!
5: REW Levels right channel error pop up, too loud!
6: End results...
7: 1 of many REW preferences set ups tried

I've tried changing and playing around the inputs and ouputs and double/treble checked the speakers are giving out consistent measurements at 85db. Prior to these testings this evening I recorded and mixed a freind on accoustic guitar and vocals with some sample choirs and there was no hiccups or software/hardware issues at all.

I appreciate i'm no expert on setting up rew and would be more than happy for some one to point out any errors. The reason the measurements were taken at 75db was to avoid any feedback.

 

[skid00]

Where your input and output show "usb codec", my input is my UMIK-1 microphone, and my output is speaker-Topping D30 Pro.

I think you are looping back thru that usb codec.

Are you using a calibrated microphone, or a recording microphone?

 

[John Mulcahy]

Looks like your problems happen when you send output to channel 2 of the USB audio codec, which is the same side as the input channel. That makes me suspect there is a monitoring path active. Since ASIO4All is just a wrapper around WDM drivers that could be "Listen to this device" selected on the audio properties for the mixer mic input, or the mixer is set up to monitor its input. You don't mention what it is, so hard to comment any further on it. If it has a mix knob, for example, that should be all the way around to PC/DAW. You can turn off the measurement SPL limit protection by just unchecking the box, but if there is a feedback path it may get very loud.

 

[Timebandit2]

Where your input and output show "usb codec", my input is my UMIK-1 microphone, and my output is speaker-Topping D30 Pro.

I think you are looping back thru that usb codec.

Are you using a calibrated microphone, or a recording microphone?

Unfortunately Behringer CF8000 (calibrated) is not listed in any of REW's ins/outs
so cant select it, likewise with Allen & Heath or Sonic Core unless Jave is selected, it will show Sonic-Core but thats 16 channel optical which is not avalable on the Allen & Heath desk which is on loan specificantly for this purpose.

 

[Timebandit2]

Looks like your problems happen when you send output to channel 2 of the USB audio codec, which is the same side as the input channel. That makes me suspect there is a monitoring path active. Since ASIO4All is just a wrapper around WDM drivers that could be "Listen to this device" selected on the audio properties for the mixer mic input, or the mixer is set up to monitor its input. You don't mention what it is, so hard to comment any further on it. If it has a mix knob, for example, that should be all the way around to PC/DAW. You can turn off the measurement SPL limit protection by just unchecking the box, but if there is a feedback path it may get very loud.

Thankoyu for your observations John.

There is no software mixer involved other than the basic windows system (see screen shot) with Asio4all as you noted, it specificaly for that reason I'm using the little Allen and Heath analog mixer, its very straight forward, the calibrated mic is going into channel 1 straight to the default setting which direct mix out on xlr which in turn feed the presonus scepters via their xlr inputs, there are no routing, foldback, headphone of fx sends buttons or hardware whatsoever selected between the mic going in and the sound coming out.

The Allen & Heath is seen by windows as a generic audio device (see attached screen shot) so it has to be something to do with with the way USB audi codecs. Ive tried just about every combination in the preferencs, measurement and generator. Maybe a basic generic REW preset with labels such as Mic in - Out to Speaker labels rather than whats there now. Is usb audio codec 1 the left channel or right and left in? Is audio codec 2 the right channel or right and left in? the fact that configurations in the preferences can be changed in Measure and Generator pages can also be confusing unless they have automatic status updates, in some instances its not possible to open one window when other are open. What's even stranger is that I did manage to get a set of measurements the other night but, if I load that mdat in, it has all the same problems I;m getting now, do they not save the preferences in that mdat?

Think i'll just stick the DEQ2496 in be done with it, thats a oopsy do but its quite straight forward once one manages to find the little icon to turn the mic input on, though that would be self defeating of this whole excersize!

 

[John Mulcahy]

The labels come from Windows rather than REW. If a device doesn't supply a name it gets a generic label, USB Audio Codec in the case of the mixer you have. Where channels are numbered 1 = left and 2 = right. They are inputs if they appear on an input device, outputs if they appear on an output device. If you can tap on the mic and hear it coming from the speakers then the Allen & Heath is set up to put the mic input on the mix output and you should correct that. You said the mic is on channel 1 of the mixer so I'm not sure why you show channel 2 selected as the input on your screenshots.

 

[Timebandit2]

Thanks for the info in the Codec's. I've just ran a setup test without changing a thing except for the ASIO device, the first thing I notice is the levels on the measurement page, see screen shots:

Yes, sorry, i was interupted and hadn't finished the post, I must have accidently hit post rather than preview when I left the room., now I can't remeber what I wrote! I'm breaking this into step by step excersize, I would really like to understand how REW works. As you can see, there is quite a difference in the left and right channel levels from with REW though when both are in a stereo matrix it returns to balance.

The same is true on both asio and java drivers, despite REW being calibrated by its own SPL meter/generator outputs from both left and right from PC via USB to mixing desk>speakers and external meters to produce a perfectly balanced system. Like wise if Cubase/Wavelab and other DAW/Editors/Video editors or other test CD's etc are run on the PC, the system has perfectly matching outputs to left and right channels no matter which set of monitors are connected. So the first question is, why is REW acting in this way, if there is user error in the way REW is being setup, please point me in the right direction.

With regards to the microphone, if its not picking up my voice then its certainly not going to pick up the test tones and noise being put out by REW. Thats why the DAW/audio system has been calibrated to 85db's and REW meaurements taken at 70-75 db so as not to cause feedback, its very similar to the way the trusty old DEQ2496 works except thats a standalone.

 

[John Mulcahy]

Which screenshots are you referring to, did you mean to attach some?

 

[Timebandit2]

Which screenshots are you referring to, did you mean to attach some?

Yes i did sorry, ive updated it now!

 

[John Mulcahy]

With regards to the microphone, if its not picking up my voice then its certainly not going to pick up the test tones and noise being put out by REW.

Perhaps this is where the misunderstanding lies. The signal the mic picks up is required, of course, and it should be returned on the USB connection. But it must not be mixed back into the output. There must be no possibility of any feedback no matter what levels are used. The only thing that goes to the outputs must be the test signal REW generates and your mixer will need to be set up to make sure that happens. All that is needed for measurement is an audio interface with inputs and output, not a mixer. The odd behaviours you are seeing are not caused by REW, they are caused by the mixer and its configuration. Mixers are great for recording and pointless for measuring, no mixing should happen for a measurement, just a test signal being sent to the speakers and the signal the speakers produce being recorded from the mic.