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Lets talk REW (Room EQ Wiz) and how best to use it.


joessportster

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OK Hearing not being what it used to be. I am wanting to look at graphs , figures, correction's etc... I will admit I am a Dumba$$ when it comes to this stuff But I am willing to learn / try. I downloaded the latest REW software and I bought the Umik-1 I downloaded my individual mics calibration code, codes. I connected to my pc which is also my main source for music. I tested/ calibrated the  SPL It was at 94ish DB with the mic setting almost between the speakers and straight up (I did not have a long enough usb for the mic to reach listening position (I am going to get an extension cable for that issue, PC must stay put.)

 

I actually did a small graph / measurement for bass 20-200hz sweep and saw an approx  20db drop at 40HZ Everything else looked pretty much like  a good shallow climb. I do all my messaging etc from laptop and the REW is on my pc so I will get the pics straightened out tomorrow so I can post measurements

 

1 thing I read is I can run a measurement and then use EQ to fix, but then it states using a minidsp to load the eq on NOW I AM LOST (Remember DUMBA$$, Thats me, not ashamed to say it. I can do lots of things but this is not 1 of them and I would like to get on a good path without months of catching up reading

 

My whole reason for getting the mic and rew is I would like to be able to play with my speakers add tweeters, decouple from the floor, raise and lower them you know that whole obsessive compulsive cant leave stuff alone thing. and then be able to measure what this or that change did for the sound. Who's with me ?

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REW is an amazing program that leads to endless tweaks.  There is always something new to learn about it -sort of like Photoshop.  I would start by using REW + your UMIK to get the best SPL graph with minimal room reflections by positioning your speakers.  Then, phase-2 is to dial this in by creating an EQ filter in REW (using a light hand and favoring negative corrections over adding sound), and then exporting this filter to your mini-DSP.  I'm not sure what method the mini-DSP uses for this, but other programs accept a .wav file exported from REW that contains the EQ correction filter.  This is a good tutorial that applies to everything you are asking about, except it exports a convolution filter to Roon rather than to a mini-DSP:

https://community.roonlabs.com/t/a-guide-how-to-do-room-correction-and-use-it-in-roon/23800

 

One more note - that 40hz suck-out could be a room null right at the spot you have your UMIK.  Trying to correct a room-null by adding sound doesn't really work.

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14 minutes ago, joessportster said:

Who's with me ?

YEAH!  My Umik mic is coming in a couple of days :D  

Think I have the same approach as you ... willing to play with my speakers, etc ... but not ready for active crossovers :(  ... the mini-dsp is a pre-amp processor to "equalize" ( I think).

Keep us posted :D 

Cheers, Emile

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I've had my mic, including rew and a new laptop, for 6+ month's... I still have not used it.

 

One thing that worries me is that many folks use the system to flatten out response to the point where the dimensions in the presentation (the forward elements and pushed back elements) is also very flat and uninspiring.

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Good point Schu. That is 1 thing I will watch for, I will not have my imaging screwed with again. I finally got back to speakers I like and get a great soundstage. now I really just want a decent response from 30ish HZ and up to my hearing limits and have that response balanced as much as possible

 

3 hours ago, pbphoto said:

REW is an amazing program that leads to endless tweaks.  There is always something new to learn about it -sort of like Photoshop.  I would start by using REW + your UMIK to get the best SPL graph with minimal room reflections by positioning your speakers.  Then, phase-2 is to dial this in by creating an EQ filter in REW (using a light hand and favoring negative corrections over adding sound), and then exporting this filter to your mini-DSP.  I'm not sure what method the mini-DSP uses for this, but other programs accept a .wav file exported from REW that contains the EQ correction filter.  This is a good tutorial that applies to everything you are asking about, except it exports a convolution filter to Roon rather than to a mini-DSP:

https://community.roonlabs.com/t/a-guide-how-to-do-room-correction-and-use-it-in-roon/23800

 

One more note - that 40hz suck-out could be a room null right at the spot you have your UMIK.  Trying to correct a room-null by adding sound doesn't really work.

Thats good to know, first thing I did when I saw that measurement was run straight to my parametric EQ in j-river and boost 40hz 3 db (i did not really hear a difference) I need to get the mic in my listening position thats where I want to know how things are stacking up.  Also I do not currently have a mini dsp so wont be using the eq feature right away unless I can get close using the eq in J-River (that wont help when playing a disc though

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8 hours ago, Schu said:

I've had my mic, including rew and a new laptop, for 6+ month's... I still have not used it.

 

One thing that worries me is that many folks use the system to flatten out response to the point where the dimensions in the presentation (the forward elements and pushed back elements) is also very flat and uninspiring.

 

I also wonder about the frequency response of a mic down to 20HZ.

JJK

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pretty obvious the difference the cones made the dip  at 35 - 50 ish hz is much sharper with the cones in place not sure what that means all measurements are taken from the listening position 6 feet from the speakers. What do you guys think ? to me it seems no cones would be better because the dip is not as severe 

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I thought a pic of the speakers might help some, I dont actually use the bass augmentation as SUBS in the general sense, They are only for support after the horns die off, 12" peerless XLS in a 1 cubic foot sealed enclosure filled with stuffing.  Listening with the cones in place bass may be sharper more focused

speaker.PNG

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Amp camp Amps with linear power supplies on the fostex BK-16, and Crown XLS 1002 on the peerless bass also have a marchand Bassis on the bass. Bi=Amped basically

 

The amp camps sound as good as pretty much any tube amp I can recall.. Set up is coming together nicely IMHIO.

 

Soundtrack to Dark Knight playing really liking the tighter more accurate sound of the bass, perhaps those sharper peaks on the measurement mean less distortion elsewhere ?

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50 minutes ago, CECAA850 said:

That's why you don't choose asthetics to determine sub location.  Move them around the room and take some more readings.

Not a choice of aesthetics  at all, I am not using subs in the typical sense. They are an extension of the horn speaker. (Not sure how to explain myself) I am looking at the set up as a 2 way speaker actively crossed at 67hz, the lower speaker handling everything below 67 and the top speaker covering the balance above 67.  I am getting Exactly what I want from the Bass speakers they are imaging very well along with the horns and are very coherent.  The sound comes together nicely as though it were all in 1 box (one of my main goals)

 

I fear I was very misleading by calling them subs, and that name has stuck

 

They are in reality of course subs, Drivers and cabinets which is why I fell into the name. 

 

What I am trying to use REW for is to figure out if there are any HOLES between the top and bottom where I can simply adjust the crossover point. It is said that the BK16 will dig down to 55HZ  in room, I have yet to find any real measurements on this particular speaker and of course all rooms will affect differently. so you should see what I am trying to do.

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1 minute ago, joessportster said:

What I am trying to use REW for is to figure out if there are any HOLES between the top and bottom

I would think that would be best measured outside away from all boundaries.  That way you're measuring the speaker and not the room.

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That makes sense but we must do the best we can with what we have.  I am in a cervical collar, no lifting etc...etc...etc..., In my life competent help is hard to come by and My dear wife puts up with plenty for my hobby I could not ask her to move my system and PC out doors to make more accurate measurements. and then move everything back the whole time putting up with my OCD behaviors.

 

On the other hand since everything will stay where it is making adjustments with all the contributing factors in place It should offer a decent compromise. 

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OK, for those of you who have NO CLUE about this stuff (like me :D ) but want to learn more about it or try it ... here's a pretty good video explaining/applying mini-DSP and REW. 

Cheers, Emile

 

BTW ... only bought the mic ... guess I'd better buy a mini-DSP also :) 

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HELP :D Still a bit confused about hooking up a miniDSP. Want to make sure before I buy one :D 

Using a (zone 2) pre-out from my Onkyo ZR810 into my Marantz 2252B "aux" input" and assumed I could just put it in-line there.  (Instead of preamp-miniDSP-poweramp).

Please advise.

Many thanks, Emile

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further experimenting, adjusted Qb on the marchand bassis from .4 to .7 and it certainly had an affect on the measurement, checking the sound by ear will have to wait till tomorrow boys are in bed  Red is before adjustment, green are the results.

 

Anyone know of someone that can take a look at these graphs and offer an opinion on the speakers measured performance as well as possible ideas for improvement ?

marchand improvement measurement.PNG

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The onlyway you're going to improve the suck out at 50Hz is to physically move things around.  The mic is in a room null there.   Have you measured in other seating positions?

 

Thinking out loud now.  I can't recall your exact set up right now but it's possible you could have some cancellation going on there as opposed to a room null.  If you get the same drop there while measuring in other areas of the room you have a phase issue between your mains and sub or between both subs.  You'll have to start switching polarity around and measuring at that point.

 

Room nulls and phase issues look the same as they're both forms of cancellation. 

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