First time REW user needing guidance

[robile5]

I thought about room treatments and DSP for some time now, and got around to doing some measurement today.
I own a Umik 1 mic for at least a year, but due to moving and searching sh!t ever since, there was always a piece missing (darn USB cable hiding from me): Now that the search has been finalised, I did some basic measurements ( .mdat file attached). There are maybe more measurements than needed, but I wanted to see the effects of the EV Eq has. As expected, the eq on 0dB sounds best.

Measurements were made with the mic positioned where my head would be on my listening spot. Volume was also about how loud i listen.

According to my interpretation, the measurements are not that bad. The left speaker measures somewhat worst. I attribute this to the positioning of the speakers: the right one is placed in the corner, while the left one isn`t. I cannot move the speaker due to room geometry, but I will try to move some furniture create a reflective surface adjacent to the speaker.

Other than that I am wondering if I need room some treatment or just dsp the problems out?
Follow up question would be what makes sense: I listen in stereo and have no computer or dac in the chain, so the easiest solution would be a dsp between the pre and amp. Would a Minidsp 2x4 hd or t.racks 4x4 mini would suffice? From my research, those would be enough for bass, but not suitable for full freq. It is to mention that due to budgetary reasons, expensive dsp solutions are out of the question (for example dsp flex). Other option could be to sell my current pre and look for one with integrated dsp, but that would be a last case scenario.

Other than that, feel free to look at the graphs and point out the things i missed. Any feedback is appreciated.

edit: difference in output between the speakers should be ignored at this point. The preamp ballance pot was not centered

 

[Keith_W]

There is no MDAT attached.

 

[robile5]

Sorry, I attached the file, but did not see it was to large. Here is one that is a bit cleaned up

 

[OCA]

There's only a quite "failed" right speaker measurement in that mdat file. You have captured about 20ms of major pre-ringing. Some thing(s) started resonating long before the speaker started playing. It's generally not a good idea to measure speakers over a wireless bluetooth connection.

Don't worry, you will quickly learn to measure them correctly, even playing the sweep and managing to capture is a very good starting point. And then even the cheapest miniDSP can solve your DSP needs.

 

[Keith_W]

1. Only the right speaker was included in your MDAT. Try to include both speakers, measured independently. If it's too large for ASR to host, host it yourself and post a link.
2. Measurement was taken without a timing reference.

3. The appearance of this impulse and step response suggests the measurement is meaningless anyway. Look at how filthy that impulse response is, and the step response is utterly weird. I don't know what caused this, probably an error in your settings or your system setup.
4. A MiniDSP can take over the preamp function, depending on what else you need your preamp to do. Buy the cheapest MiniDSP that has the functions that you need - in your case, 4 channels out and a volume control.

There is a link to a free REW eBook in my link. It will take you a long time to read that, so I suggest you skip some of the more advanced sections. Read the section on how to take measurements, and then how to interpret the frequency response. Good luck!

 

[robile5]

So i redid the measurements with a timing reference, and made sure I save both speakers not just one.
The errors in the former measurements might have been due to connecting the laptop to the speakers via bluetooth. Hopefully they are better this time around.
For today the testing session is over, and I will go on an read the REW eBook provided during the evening.

 

[OCA]

Measurements are correct this time.

Attached are your filters (biquads) for miniDSP 2x4HD

You don't need anything else for 90% improvement compared to what you are listening right now.

 

[robile5]

Tanks OCA for that, now I only have to source a minidsp.
As there already is a EQ unit between the pre and amp (to improve bass response), I take it that I will have to take the measurements again, and apply bass correction provided by the eq.

 

[OCA]

Tanks OCA for that, now I only have to source a minidsp.
As there already is a EQ unit between the pre and amp (to improve bass response), I take it that I will have to take the measurements again, and apply bass correction provided by the eq.

If it's an eq device covered in REW, this might be much easier, or if you know its tech specs.

 

[robile5]

I found a graph of what the eq does, and that is a 6dB boost at 32 hz. There are also 3 slopes for the frequency, but flat works best for me.

Found a minidsp on the bay for not a lot of cash and grabed it. If the improvement are obvious, I will sell some gear to finance a better performing solution

 

[OCA]

I found a graph of what the eq does, and that is a 6dB boost at 32 hz. There are also 3 slopes for the frequency, but flat works best for me.

Found a minidsp on the bay for not a lot of cash and grabed it. If the improvement are obvious, I will sell some gear to finance a better performing solution

That looks like a primitive equal loudness adjustment. It's not useful for room correction.

 

[robile5]

That looks like a primitive equal loudness adjustment. It's not useful for room correction.

It is not for room correction, but for bass response of the speaker. The speakers are EV sentry III's, which can be tuned, by covering one of the bass reflex openings and eq-ing, to extens the bass response to 28hz (from 40).
The eq is currently hooked between the pre and amp, and the minidsp should at best replace it.

 

[robile5]

It seems that I can not make any progresses with dsp.
Acquired a minidsp 2x4, applied the provided quads, but I am not able to make any measurements with REW.
Actually I can but the output to speakers pruduces nasty pop and crackle noises. This only thru rew, If I play music from the laptop, it sounds just right. This was also the case before the dsp was swapped in, but after a few unplugging and plugging the cable, it worked fine. Also tried other cable between laptop and amp, other input on the amp, and different settings in REW.
Other than that the dsp seems to work just fine, only not sure if it sounds better (bass seems cleaner and with more kick) or it is just my impression.

 

[Keith_W]

Make sure the sample rate of REW matches the sample rate of your MiniDSP.

 

[Sokel]

It seems that I can not make any progresses with dsp.
Acquired a minidsp 2x4, applied the provided quads, but I am not able to make any measurements with REW.
Actually I can but the output to speakers pruduces nasty pop and crackle noises. This only thru rew, If I play music from the laptop, it sounds just right. This was also the case before the dsp was swapped in, but after a few unplugging and plugging the cable, it worked fine. Also tried other cable between laptop and amp, other input on the amp, and different settings in REW.
Other than that the dsp seems to work just fine, only not sure if it sounds better (bass seems cleaner and with more kick) or it is just my impression.

You can measure with the "from file" mode of REW:

Is the same as if you were playing music.

What you have to do is generate a test sweep signal from REW's generator (make sure you include the acoustic reference option to it, right samplerate, etc) for any channel you want, drug it where the the pic says, hit "measure" and then play back the same sweep test file the way you listen to music (beware of levels, choose something like -12dB when you generate it)

 

[robile5]

Make sure the sample rate of REW matches the sample rate of your MiniDSP.

Sample rate matches and most of all can not be changed.

You can measure with the "from file" mode of REW:

This worked but it is a bit more work thank I would like.

As this took a lot longer than I thought, I did not have enough time to look at the before/after DSP measurement. What is pretty obvious is that one speaker has a large dip somewhere around 40hz that is way more than 9db.

Will do some more measurements during the weekend