Simplified REW Setup and Use (USB Mic & HDMI Connection) Including Measurement Techniques and How To Interpret Graphs - Page 79 - AVS Forum
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post #2341 of 12881 Old 04-02-2013, 06:35 AM
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Originally Posted by AustinJerry View Post

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Originally Posted by turboman123 View Post

See announcement from miniDSP regarding UMIK-1 mic:
http://www.minidsp.com/forum/2-announcements/8607-umik-1--10hz--spl-readings-in-rew#8607

 

This stuff upsets me.  Now I wonder how accurate the UMM-6 is.  

 

Herb and Cross Spectrum Labs have an unparalleled reputation AFAIK, so why doubt the accuracy of their calibration? In fact, IIRC, mine came with a graph showing the comparison between it and Herb's reference mic.

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post #2342 of 12881 Old 04-02-2013, 06:36 AM
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Originally Posted by Heinrich S View Post

Will this sort out the consistency issues with the mic? Or will it just allow us to measure down to 10 Hz?

 

I'm not up to speed on the consistency issues but the announcmeent did mention a new version of REW in the works.  Sounds like the two will go together to improve the performance of the UMIK-1.  I wonder if John is making any progress on incorporating the UMM-6 directly into REW as well (to avoid the SPL calibration step)?

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post #2343 of 12881 Old 04-02-2013, 06:37 AM
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Originally Posted by AustinJerry View Post

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Originally Posted by turboman123 View Post

See announcement from miniDSP regarding UMIK-1 mic:
http://www.minidsp.com/forum/2-announcements/8607-umik-1--10hz--spl-readings-in-rew#8607

 

This stuff upsets me.  Now I wonder how accurate the UMM-6 is.  

 

The most shocking part of that announcement was the admission that they didn't have a speaker that could reproduce 10Hz accurately?!  Ok, 10Hz is not easily reproduced but surely a company with their means could find one, no?!

 

They could have popped round to my place - I could have given them a choice of two. biggrin.gif

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post #2344 of 12881 Old 04-02-2013, 06:40 AM
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They could have popped round to my place - I could have given them a choice of two. biggrin.gif

 

Exactly my thoughts...

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post #2345 of 12881 Old 04-02-2013, 06:44 AM
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Hey KB, as I was sifting through countless posts in this thread the other day, I realized it has been over a month since you started experimenting with the filters in REW.  Have any insights yet into the pros/cons of parametric EQ with Audyssey to share with those of us still behind your learning curve?! tongue.gif

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post #2346 of 12881 Old 04-02-2013, 06:53 AM
 
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Originally Posted by AustinJerry 
This stuff upsets me. Now I wonder how accurate the UMM-6 is.

What do you mean?
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post #2347 of 12881 Old 04-02-2013, 07:03 AM
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Originally Posted by jkasanic View Post

Hey KB, as I was sifting through countless posts in this thread the other day, I realized it has been over a month since you started experimenting with the filters in REW.  Have any insights yet into the pros/cons of parametric EQ with Audyssey to share with those of us still behind your learning curve?! tongue.gif

 

I've not yet done any real work on it. I have mastered the Behringer 1124P and know how to use it, to program it, to connect it to REW via my laptop and a MIDI interface and so on. I have played with REW a lot and know how to use the EQ section (I think). But I have not actively set it all up and measured the results. I am taking a break from many weeks of intensive measuring, to catch up with some movies from my 'unwatched' pile. TBH it all sounds so good, I am not sure I can improve on it much (although I have said that before...).

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post #2348 of 12881 Old 04-02-2013, 07:04 AM
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Originally Posted by Heinrich S View Post

Quote:
Originally Posted by AustinJerry 
This stuff upsets me. Now I wonder how accurate the UMM-6 is.

What do you mean?

 

Is this a genuine question or are you on another of your self-admitted trolling ventures, now in this thread since the other thread you inhabited got wise to you?

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post #2349 of 12881 Old 04-02-2013, 07:31 AM
 
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Originally Posted by kbarnes701 
Is this a genuine question or are you on another of your self-admitted trolling ventures, now in this thread since the other thread you inhabited got wise to you?

It is a genuine question as I don't know if I should cancel my Dayton order and go for the UMIK or not. I don't know what the actual story is right now.
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post #2350 of 12881 Old 04-02-2013, 10:07 AM
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Originally Posted by Heinrich S View Post

Quote:
Originally Posted by kbarnes701 
Is this a genuine question or are you on another of your self-admitted trolling ventures, now in this thread since the other thread you inhabited got wise to you?

It is a genuine question as I don't know if I should cancel my Dayton order and go for the UMIK or not. I don't know what the actual story is right now.

In that case I will give you the benefit of the doubt and answer ;)  IMO the UMM-6, individually calibrated by Cross Spectrum Labs is the better option. It comes with individual cal files for 0, 45 and 90 degrees, the latter being the one you need for REW measurements of the type discussed in this thread. The UMIK-1 mic, AIUI, only comes with a cal file for 0 degrees which is not what we want. A small advantage of the UMIK-1 mic is that REW is able to recognise the mic and so it does not need calibrating with a separate SPL meter to 80dB prior to running a REW session. However, as this takes about 5 seconds it is hardly of any consequence, so long as you have an SPL meter. If you do not have an SPL meter than I would suggest buying one as they are useful for many reasons with an AV setup, cost only a modest sum and really ought to be on the shopping list before something as complex/sophisticated as REW and calibrated mics.

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post #2351 of 12881 Old 04-02-2013, 10:23 AM
 
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Originally Posted by kbarnes701 
In that case I will give you the benefit of the doubt and answer wink.gif IMO the UMM-6, individually calibrated by Cross Spectrum Labs is the better option. It comes with individual cal files for 0, 45 and 90 degrees, the latter being the one you need for REW measurements of the type discussed in this thread. The UMIK-1 mic, AIUI, only comes with a cal file for 0 degrees which is not what we want. A small advantage of the UMIK-1 mic is that REW is able to recognise the mic and so it does not need calibrating with a separate SPL meter to 80dB prior to running a REW session. However, as this takes about 5 seconds it is hardly of any consequence, so long as you have an SPL meter. If you do not have an SPL meter than I would suggest buying one as they are useful for many reasons with an AV setup, cost only a modest sum and really ought to be on the shopping list before something as complex/sophisticated as REW and calibrated mics.

Thanks. smile.gif Well I have a Galaxy CM-140 SPL meter that has been calibrated by Cross Spectrum so I guess that's good enough? I think you have put my fears to rest on which mic to go for. No cancelling of the UMM-6. I don't follow the mic issues as closely as others, so when I hear stories about mics having consistency issues, it does bother me a little. Good to know the UMM-6 so far seems like a great choice. Is there a reason why you suggest 80 dB for the calibration level? I would have used 75 dB.
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post #2352 of 12881 Old 04-02-2013, 10:34 AM
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Originally Posted by Heinrich S View Post

Quote:
Originally Posted by kbarnes701 
In that case I will give you the benefit of the doubt and answer wink.gif IMO the UMM-6, individually calibrated by Cross Spectrum Labs is the better option. It comes with individual cal files for 0, 45 and 90 degrees, the latter being the one you need for REW measurements of the type discussed in this thread. The UMIK-1 mic, AIUI, only comes with a cal file for 0 degrees which is not what we want. A small advantage of the UMIK-1 mic is that REW is able to recognise the mic and so it does not need calibrating with a separate SPL meter to 80dB prior to running a REW session. However, as this takes about 5 seconds it is hardly of any consequence, so long as you have an SPL meter. If you do not have an SPL meter than I would suggest buying one as they are useful for many reasons with an AV setup, cost only a modest sum and really ought to be on the shopping list before something as complex/sophisticated as REW and calibrated mics.

Thanks. smile.gif Well I have a Galaxy CM-140 SPL meter that has been calibrated by Cross Spectrum so I guess that's good enough? I think you have put my fears to rest on which mic to go for. No cancelling of the UMM-6. I don't follow the mic issues as closely as others, so when I hear stories about mics having consistency issues, it does bother me a little. Good to know the UMM-6 so far seems like a great choice. Is there a reason why you suggest 80 dB for the calibration level? I would have used 75 dB.

Good meter. Most of us, I think, in this thread have the UMM-6 and AFAIK everyone is happy with their choice.

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post #2353 of 12881 Old 04-02-2013, 11:05 AM
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Quote:
Originally Posted by Heinrich S View Post

Quote:
Originally Posted by kbarnes701 
In that case I will give you the benefit of the doubt and answer wink.gif IMO the UMM-6, individually calibrated by Cross Spectrum Labs is the better option. It comes with individual cal files for 0, 45 and 90 degrees, the latter being the one you need for REW measurements of the type discussed in this thread. The UMIK-1 mic, AIUI, only comes with a cal file for 0 degrees which is not what we want. A small advantage of the UMIK-1 mic is that REW is able to recognise the mic and so it does not need calibrating with a separate SPL meter to 80dB prior to running a REW session. However, as this takes about 5 seconds it is hardly of any consequence, so long as you have an SPL meter. If you do not have an SPL meter than I would suggest buying one as they are useful for many reasons with an AV setup, cost only a modest sum and really ought to be on the shopping list before something as complex/sophisticated as REW and calibrated mics.

Thanks. smile.gif Well I have a Galaxy CM-140 SPL meter that has been calibrated by Cross Spectrum so I guess that's good enough? I think you have put my fears to rest on which mic to go for. No cancelling of the UMM-6. I don't follow the mic issues as closely as others, so when I hear stories about mics having consistency issues, it does bother me a little. Good to know the UMM-6 so far seems like a great choice. Is there a reason why you suggest 80 dB for the calibration level? I would have used 75 dB.

 

ICBW, but I think we started using 80dB in response to the higher noise floor with the USB mics.

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post #2354 of 12881 Old 04-02-2013, 12:37 PM
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Originally Posted by Heinrich S View Post

Is there a reason why you suggest 80 dB for the calibration level? I would have used 75 dB.

 

I have been told that there should be at least 40dB of headroom between the measurement level and the noise floor in order to have useful measurements for bass decay.  Thus, my recommendation was to calibrate to at least 80dB, assuming a typical noise floor of ~40dB.  I would have a hard time proving 80dB is better than 75dB, or 85dB, etc.

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Originally Posted by AustinJerry 
I have been told that there should be at least 40dB of headroom between the measurement level and the noise floor in order to have useful measurements for bass decay. Thus, my recommendation was to calibrate to at least 80dB, assuming a typical noise floor of ~40dB. I would have a hard time proving 80dB is better than 75dB, or 85dB, etc.

Okay, I mentioned the 75 dB thing because I would normally set my speaker levels to 75 dBs as my reference level. Perhaps I'm thinking of something completely different to what is being discussed.
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post #2356 of 12881 Old 04-02-2013, 03:29 PM
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Okay, I mentioned the 75 dB thing because I would normally set my speaker levels to 75 dBs as my reference level. Perhaps I'm thinking of something completely different to what is being discussed.

 

The mic can be calibrated at any level.  Once it is calibrated, you can use the mic to set your speakers to 75dB, no problem.  The calibration level is only a reference point aligning the external volume produced by your AVR/speakers, and the internal electrical signal that the mic passes to REW.

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post #2357 of 12881 Old 04-02-2013, 05:29 PM
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Quote:
Originally Posted by Heinrich S View Post

Quote:
Originally Posted by AustinJerry 
I have been told that there should be at least 40dB of headroom between the measurement level and the noise floor in order to have useful measurements for bass decay. Thus, my recommendation was to calibrate to at least 80dB, assuming a typical noise floor of ~40dB. I would have a hard time proving 80dB is better than 75dB, or 85dB, etc.

Okay, I mentioned the 75 dB thing because I would normally set my speaker levels to 75 dBs as my reference level. Perhaps I'm thinking of something completely different to what is being discussed.

 

You're not trying to establish reference level when you run REW. All you need to do is ensure that your dB level is high enough that it clears the noise floor by a good margin, as Jerry says. The greater the gap between the background noise level and the test tones from REW, the more accurate the measurement will be. It was originally mooted that we set a mic calibration level of 100dB but for fear of destroying our speakers and deafening ourselves, we ended up settling on 80dB. IIRC John M, author of REW, confirmed that this was fine.

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post #2358 of 12881 Old 04-02-2013, 05:50 PM
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Jerry, I changed my mind and ordered the ULS-15 dual drive package. The ULS has a smaller enclosure that will go better on the front wall. Delivery should be in a few days.

How well does the wireless connection work? I don't know if I will be needing it since the subs will be placed close to the player, but if it will cut some of the clutter...

Also went with the rosewood finish.

Now the waiting game.

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post #2359 of 12881 Old 04-02-2013, 06:00 PM
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Quote:
Originally Posted by Heinrich S View Post

Quote:
Originally Posted by AustinJerry 
I have been told that there should be at least 40dB of headroom between the measurement level and the noise floor in order to have useful measurements for bass decay. Thus, my recommendation was to calibrate to at least 80dB, assuming a typical noise floor of ~40dB. I would have a hard time proving 80dB is better than 75dB, or 85dB, etc.

Okay, I mentioned the 75 dB thing because I would normally set my speaker levels to 75 dBs as my reference level. Perhaps I'm thinking of something completely different to what is being discussed.
Just thought I should clarify, to avoid any possible confusion, that there is a distinct difference between system THX Reference level calibration vs REW SPL calibration levels.

The 75db calibration levels folks often refer to is for THX Reference level calibration (and is commonly performed by most avr's with room correction technology). This constitutes outputting a test tone of known volume meant to most commonly produce a 75db SPL at the MLP. If the SPL is lower or higher due to different speaker sensitivities and distances to the MLP, the internal avr trims are adjusted to achieve the correct SPL thus ensuring that when the avr's volume is set to '0'db, what you're hearing is (theoretically) the exact loudness you're supposed to hear it at.

The REW calibration is simply calibrating the measurement setup so 75 (or 80) db SPL in REW produces that SPL with your setup.


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post #2360 of 12881 Old 04-02-2013, 07:05 PM
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Jerry, I changed my mind and ordered the ULS-15 dual drive package. The ULS has a smaller enclosure that will go better on the front wall. Delivery should be in a few days.

How well does the wireless connection work? I don't know if I will be needing it since the subs will be placed close to the player, but if it will cut some of the clutter...

Also went with the rosewood finish.

Now the waiting game.

 

See PM.

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post #2361 of 12881 Old 04-02-2013, 11:39 PM
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Here's a graph showing the improved FR. Man, the more and more you measure the clearer it gets just how hard it is to deal with a null. Raising the volume just doesn't work; it only raises the peaks all around the dips. After a few dozen measurements you really learn to appreciate REW.



Edit: I'll try a new measurement tomorrow with my Anti-Mode. Maybe it will settle the peak at 108. I'm not expecting much change. Maybe if I reset the XO above 100.

I measured the left speaker and sub separately to see which speaker is causing the peaks between 50 - 200 Hz.

The red line is the sub only.
The green line is the left speaker only with the crossover set at 120 Hz
The blue line is the left speaker only, this time set at 200 Hz.



Except for one peak I think the subwoofer response is fine. (Remember, this is an 8" sub). The left speaker, however, shows a dip at 300 Hz, followed by a peak beyond the crossover point. This may be the result of standing waves between the ceiling and the floor. When I clap my hands near the speaker, there's a short echo, fraction of a second, that I don't hear in other parts of the room. The peak is reinforcing the sub's frequencies in the upper bass and making it louder than it should be. I can listen with the crossover set at 200 Hz, for now, but a correction will definitely be needed.

Edit: I've been thinking about this some more, it may be that the 8" subs are simply not a good match for my mains. The graph proves they don't play much lower than my mains. Also, the peak near the crossover may not be a peak at all -- it only looks that way, because of the large drop at 300 Hz. If there were no dip there, the rest of the curve would look relatively flat. I just have to find out what's causing this dip.

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post #2362 of 12881 Old 04-03-2013, 06:56 AM
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On page 10, AustinJerry posted a PDF guide that seems very useful.

Is that the most updated version of the guide? I expect my UMM-6 later this week and am giving this a go with an HDMI connection.

"The Scuba Tank" thread here
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Good meter. Most of us, I think, in this thread have the UMM-6 and AFAIK everyone is happy with their choice.

I agree that the UMM-6 seems to be a great choice. If the UMIK can get their stuff sorted to 10 hz it would make it a slightly closer competitor. My Empire probably only goes to around 17hz in my room anyway, so I don't need 5hz and I reckon only a very select few of the posters here even get to 10hz.

At the end of the day, guys like me who use the mic to just sort their mid-range subs are not going to cry if it is a db or two off...you will still get the general trend of nulls and modes in your room with the UMIK + REW and it will allow you to experiment to get you to where you are happy with the sound coming from them. The Mini DSP in addition gives you fantastic possibilities to waste lots of your time to try to correct things as well.
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post #2364 of 12881 Old 04-03-2013, 07:03 AM
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On page 10, AustinJerry posted a PDF guide that seems very useful.

Is that the most updated version of the guide? I expect my UMM-6 later this week and am giving this a go with an HDMI connection.

 

Yes, that is the current version.  When updates are posted, I always edit that location.

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post #2365 of 12881 Old 04-03-2013, 07:38 AM
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Originally Posted by scubasteve2365 View Post

On page 10, AustinJerry posted a PDF guide that seems very useful.

Is that the most updated version of the guide? I expect my UMM-6 later this week and am giving this a go with an HDMI connection.

There's also a link in his sig. wink.gif


Downloadable FREE demo discs:
http://www.avsforum.com/t/1475769/de...ently-authored 

Did you really need to quote that entire post in your reply?
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post #2366 of 12881 Old 04-03-2013, 07:49 AM
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Quote:
Originally Posted by Pres2play View Post

Quote:
Originally Posted by Pres2play View Post

Here's a graph showing the improved FR. Man, the more and more you measure the clearer it gets just how hard it is to deal with a null. Raising the volume just doesn't work; it only raises the peaks all around the dips. After a few dozen measurements you really learn to appreciate REW.



Edit: I'll try a new measurement tomorrow with my Anti-Mode. Maybe it will settle the peak at 108. I'm not expecting much change. Maybe if I reset the XO above 100.

I measured the left speaker and sub separately to see which speaker is causing the peaks between 50 - 200 Hz.

The red line is the sub only.
The green line is the left speaker only with the crossover set at 120 Hz
The blue line is the left speaker only, this time set at 200 Hz.



Except for one peak I think the subwoofer response is fine. (Remember, this is an 8" sub). The left speaker, however, shows a dip at 300 Hz, followed by a peak beyond the crossover point. This may be the result of standing waves between the ceiling and the floor. When I clap my hands near the speaker, there's a short echo, fraction of a second, that I don't hear in other parts of the room. The peak is reinforcing the sub's frequencies in the upper bass and making it louder than it should be. I can listen with the crossover set at 200 Hz, for now, but a correction will definitely be needed.

Edit: I've been thinking about this some more, it may be that the 8" subs are simply not a good match for my mains. The graph proves they don't play much lower than my mains. Also, the peak near the crossover may not be a peak at all -- it only looks that way, because of the large drop at 300 Hz. If there were no dip there, the rest of the curve would look relatively flat. I just have to find out what's causing this dip.

 

I think you're going the wrong direction with your XO.  Your less capable sub is rolling off at 100Hz so a crossover above this is really not helping.  I would suggest trying a XO in the 60-100Hz region (try 80Hz wink.gif). The dip from 200-400Hz will need EQ or repositioning of your speaker (probably not a very good option depending on your room?).

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post #2367 of 12881 Old 04-03-2013, 09:06 AM
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^^^
Something is wrong for sure. I get a bump at the XO point if I set any lower than 120Hz.

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post #2368 of 12881 Old 04-03-2013, 09:13 AM
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what receiver/prepro are you using?  Did you try the sub distance tweak to improve the crossover transition?

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post #2369 of 12881 Old 04-03-2013, 10:25 AM
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I'm have one of the Oppo Univeral Players that also functions as a prepro and has no room correction. Jerry and Keith have both recommended I get the Onkyo 818 for Audyssey feature. I totally agree with them but I'm holding back a few more weeks while I try out a new pair of subs and further room treatments. I'd much rather maintain the direct analog connection between the player and the power amps, if I can.

The sub distance tweak is interesting. I actual tried this a week ago, extending the speaker distance from 9 feet to 15 feet, and found that it did improve response, to a certain point. Was your distance tweak just a random distance that you selected?

Edit: just clicked on sub distance tweak in your post. I did not try the method they mentioned since I don't have Audyssey.

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post #2370 of 12881 Old 04-03-2013, 11:22 AM
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The procedure would be the same with or without Audyssey.  The point is you're trying to compare the individual responses with the combined response (basically what you already did with your L and Sub channels) and then see the effect of varying the sub distance (delay).  Once you get Audyssey, you would need to repeat the procedure with it turned on.  In my setup, I tested above and below the distance set to see if there was an improvement.  The improvement showed up below the Audyssey calculated distance so then I just kept playing with distances to get the best response.  One thiing you'll want to check is how the tweak impacts your L, C and R channels plus sub individually as well as your L+R+Sub combined response.

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