Best use of Computer based measurement systems to solve Bass Problems

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JohnR

Oh, to expand on my previous post, you will also need some cables, adapters, and a mic stand. The stand is somewhat optional I suppose, if you're only doing bass, I've seen people wedge the mic in the sofa, but it's pretty inconvenient not to have one.

Cables:
* Standard mic cable, 5-6 m
* Output from sound card into stereo, usually a TRS-RCA adapter and a regular RCA cable suffices
* Loopback cable for "calibrating" soundcard. I'm somewhat undecided whether this is truly necessary. If it's done I think it's actually best done with the line-level input, so that means a short TRS-TRS cable.

jtwrace

Thanks for you vote of confidence...

Not about that whatsoever.

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I agree with John, it's about the knowledge of it and using it to ones best advantage!

Jim
Uh yeah.  That's why I've been such a proponent about it.  Sadly most think they can do it all by ear.  If you spend the time required your listening environment will be better. 

medium jim

Jason:

I'm with Kevin360 on this, in that I really like the way my system sounds.  At the end of the day, it is only me that I need to please, right or wrong. 

At some point I will take proper measurements and see where it takes me.  One thing I will not endenvour to do is go with a digital room eq correction, but that is me.

Jim

*Scotty*

John, I was planning on putting the mic at the listening position at ear level sitting on the back of the couch with enough cabling to
be able to place the laptop close enough to see the RTA from my position near the rear sub-woofer. The positions I can move the sub to are limited and consist of lateral motion towards the corner about 6ft. from its present location. The loading sub-woofer currently sees is something a little less than 2pi.
Moving the sub-woofer progressively closer to the corner would gradually shift its loading from 2pi to pi to 1/8 pi if the sub was fully in the corner.
 Somewhere along this continuum should be the location that yields the greatest improvement in damping the room's longitudinal resonant behavior. This position will also yield the flattest bass response. I have a couple more subs I can try to position to tame transverse resonances that exist between the sidewalls but I don't hold out much hope of really knocking them down much without the addition of delay to their output.
 EQ is also off the table for me as well. I don't have enough power available to boost the bass to fill in depressions in the bass response curve. This only leaves cutting the power to the response peaks on a parametric basis. In any case I don't have an equalization program for parametric digital equalization that will run on Linux anyway.
Scotty

JohnR

Somewhere along this continuum should be the location that yields the greatest improvement in damping the room's longitudinal resonant behavior. This position will also yield the flattest bass response.

I'm very interested to see how you go.

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In any case I don't have an equalization program for parametric digital equalization that will run on Linux anyway.

Ah. Which player do you use on Linux? (Apologies if this was covered somewhere else already)

jtwrace

I really like the way my system sounds.  At the end of the day, it is only me that I need to please, right or wrong. 
That is true.  You are truly the only one that needs to be happy with your system.  If you never look outside your box though you will never know what you could be missing.  In this case, I'd suspect quite a bit. 


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At some point I will take proper measurements and see where it takes me. 
Great.  I look forward to the measurements. 

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One thing I will not endenvour to do is go with a digital room eq correction, but that is me.
I agree.  I've been there and done it.   :duh:

JohnR

I guess I don't get the anti-EQ bias. Like measurements, it's just a tool. You can learn to use it effectively, or not.

jtwrace

I guess I don't get the anti-EQ bias. Like measurements, it's just a tool. You can learn to use it effectively, or not.
I try not to use it if it can be avoided.  I tried DRC and although it does help there are much better ways to accomplish the same thing.  Room treatments and maybe a slight eq if needed.

JohnR

You think DRC == EQ?

jtwrace

You think DRC == EQ?
Yes but DRC (one box unit) typically is automatic with very little flexability. 

JohnR

Yes but DRC (one box unit) typically is automatic with very little flexability.

Right... and DRC can do other tricks as well, like for example, adding random delays to try and make the response flatter. A bit like you do with your subs...

I mean, your statement above is a bit like saying "I tried an automatic pilot for my car and it didn't get me there as fast as I can drive myself, therefore I avoid using GPS units."

jtwrace

Right... and DRC can do other tricks as well, like for example, adding random delays to try and make the response flatter. A bit like you do with your subs...

I mean, your statement above is a bit like saying "I tried an automatic pilot for my car and it didn't get me there as fast as I can drive myself, therefore I avoid using GPS units."
I guess what I'm trying to say is that I want to have complete control over what gets changed and know what is getting changed.  All in one units that aren't automatic are fine but of course have their place and limitations.  Personally I do not use any eq but that's just me and my system. 

JohnR

I like to have control too. I prefer not to use DRC the way that you do, with delays messing up the timing just to make the steady-state response look good. Because the latter can be easily corrected with... um, EQ  :green:

jtwrace

with delays messing up the timing just to make the steady-state response look good.
I only use delays on my two subs that are in the back of the room.  It's really the proper way to do it from what I've been told by many pro audio guys.  And it makes sense,...That's exactly how they do live events when there are many speakers within the same event.

*Scotty*

jtwrace, what are you using to give delay to rear subs output and how many milliseconds or feet of delay do you have dialed in?
 As far as EQ of the front mains is concerned I only have 100 watts a channel of power available, even a 3dB boost is going to cause me to clip peaks. EQ could be applied to the rear sub as it has a 350 watt amplifier driving it but I don't currently have the ability to EQ only the feed to that sub.
Scotty

jtwrace

jtwrace, what are you using to give delay to rear subs output and how many milliseconds or feet of delay do you have dialed in?
Currently a DCX.  IIRC it's ~3ms on one and ~7ms on the other.


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As far as EQ of the front mains is concerned I only have 100 watts a channel of power available, even a 3dB boost is going to cause me to clip peaks. EQ could be applied to the rear sub as it has a 350 watt amplifier driving it but I don't currently have the ability to EQ only the feed to that sub.
Scotty
I do not use nor need any eq on my mains.

*Scotty*

John, I am using Rhythmbox as my music player, it is the only one that I have found that allows gapless playback. There is an EQ plugin but it is fairly crude and the EQ would be applied across the board to all channels. I could maybe cut down humps with it if they happened to coincide with the center frequencies of the filters that are available.
Scotty

*Scotty*

jtwrace, if both subs are in the same plane on the rear wall, why have you used two different delay times?
Scotty

jtwrace

jtwrace, if both subs are in the same plane on the rear wall, why have you used two different delay times?
Scotty
Because they're not on the same plane and they're not on the rear wall.

*Scotty*

I thought you were maybe using the CABS approach to optimizing the bass response in your room, my bad. Different locations mean different delays.
Scotty