Home Theater Forum and Systems banner

1 - 20 of 25 Posts

·
Registered
Joined
·
25 Posts
Discussion Starter #1 (Edited)
Im going to attempt to run REW on the new Epik Dragon subwoofer in a square room (11x11) Ive never ran REW before so im going to work it out as I go along. I have a denon 2809 with audyssey multeq xt that set my sub to -11. At -5 on my avr I have only gotten spl of 104 in the cloverfield bridge scene. It has been suggested that something is wrong and that the dragon should be more capable. Ill post graphs soon.
Edit : Although I dont fully understand what to do even after I post a graph. How do I 'fix' the inevitable problems. I dont have a bfd or such and dont really plan on buying one. So are the graphs just to say "Yep its screwed up, well nothing I can do. Good day"
 

·
Registered
Joined
·
1,405 Posts
Im going to attempt to run REW on the new Epik Dragon subwoofer in a square room (11x11) Ive never ran REW before so im going to work it out as I go along.
IMO that is the best way to learn.

I have a denon 2809 with audyssey multeq xt that set my sub to -11. At -5 on my avr I have only gotten spl of 104 in the cloverfield bridge scene. It has been suggested that something is wrong and that the dragon should be more capable. Ill post graphs soon.
No two setups are alike, but the room is certainly going to play a large role here unfortunitly.

Edit : Although I dont fully understand what to do even after I post a graph. How do I 'fix' the inevitable problems. I dont have a bfd or such and dont really plan on buying one. So are the graphs just to say "Yep its screwed up, well nothing I can do. Good day"
There is most always room for improvement. Placing it in a corner and using a PEQ might help. It also may help to try adding a second Dragon in another corner, preferably up front. It really will depend on your taste and what qualifies as the better result since typically placing it in the corner is not going to give the most fast response. If SPL is what your after placing it in the corner should certainly help, and since likely the sub is dialed in very low, using REW should help give a more accurate level with calibration.
 

·
Registered
Joined
·
25 Posts
Discussion Starter #3
IMO that is the best way to learn.

Maybe im an idiot but how exactly do you change anything that these graphs represent? Its not like if I have a null or peak at 20hz that I can just walk over to the 20hz nob and turn it up or down to smooth it out.
 

·
Premium Member
Joined
·
2,620 Posts
IMO that is the best way to learn.

how exactly do you change anything that these graphs represent?
You can improve the acoustics of your room - and your new sub's interaction with them - to some extent with bass traps. One problem is that your room is square, so you will discover that room resonances that coincide with both dimensions will add up and will be more difficult to control. However, the resonances at 11 feet will be relatively high in the bass frequency range, and that is where bass traps can be more effective.

The name "bass trap" is kind of a misnomer; it is not intuitive that bass absorption will increase bass extension and smoothness - but that is exactly what happens.

You will find that there is a wealth of technical assistance on this forum. However, to get the most benefit of it I suggest that you do some reading on room acoustics and how room treatments work. A very good source of info is Ethan Winer's website:

http://www.realtraps.com/info.htm

Reading his articles will better prepare you to use REW and to interpret its results. Then, post your graphs here and you will be very pleasantly surprised at the assistance that forum members will offer.
 

·
Registered
Joined
·
25 Posts
Discussion Starter #6
Hmm. I calibrated my soundcard. easy enough. where exactly do you plug the line out from the soundcard into the AVR? The v.aux input on the front of the avr? How does this generate test tones?
 

·
Premium Member
Joined
·
2,620 Posts
I would start by plugging the output of the soundcard directly into the input of the subwoofer itself. That will bypass all of the receiver's processing (on purpose) and is a good place to start.

Or, if you prefer you can plug it into any free line input, like v.aux, CD, etc. This gives you remote control of the sub volume via the receiver's remote, which can be a help when setting levels for REW.

There are some who think that Audyssey or other receiver room correction should be engaged when doing measurements, others say leave it off. I have a Denon receiver with Audyssey and prefer to have it off. I doubt that it matters much for your first measurements anyway.

I see that you are already over 5 posts, so you should be able to post your graphs. Use the Save Graph as JPEG in REW; set the size to 1000 (the widest that the board will accept. Then use the Manage Attachments option to upload your graph.

There is a standard graph scale that is preferred here for plots - 15 to 200Hz horizontal and 45 to 105db vertical. Also, the important graphs to post first are your measured frequency response and the waterfall plot. The waterfall is what you will be most interested in watching as you add room treatments.

Are you using a calibrated mic? The consensus here is that the setup mics that come with receivers do not perform well at the lowest frequencies. A popular mic is the Behringer 8000 (about $50). It needs phantom power, so something like a Behringer 802 mixer (about $60) will also be needed. But, use what you have and post some plots so that we can start seeing what is going on.

You mentioned lower than expected output from the sub - this would only be caused by the room if you happened to be sitting at a room mode null point, which is frequency specific. More likely is that Audyssey sets the sub level to match your other speakers. If you are not happy with that, go to the manual speaker setup option on the receiver and set the sub level up - or turn the volume control on the sub itself up.

By the way, I recommend GIK Acoustics for bass traps. Glenn Kuras and Bryan Pape, both from GIK, are the moderators of the room acoustics forum here. GIK is a unique company in that free support - including help in selecting the proper treatments before you buy - comes with the sale. GIK products are a good buy - good quality at prices that won't break the bank. Bryan frequents the forums and likely will chime in once you post your measurements.

Good luck and keep us posted...
 

·
Registered
Joined
·
25 Posts
Discussion Starter #8
bjhbbbbbbbbbbbbbbb.jpg

i have no idea what this means. everything seemed to be set up right and my receiver volume is at -20.5 to calibrate the spl meter properly
 

·
Premium Member
Joined
·
2,620 Posts
Your scale on the graphs is wrong. In the upper right hand corner of REW, click Graph Limits. In the popup window, set Left at 15, Right at 200, Top at 105 and Bottom at 45. Again, what mic are you using?

From what I can tell of the graph your frequency response is not bad at all. We can tell more about it when you set the graph limits. Run another one with Audyssey turned OFF. Also, run a waterfall plot and lets see what you are getting.
 

·
Registered
Joined
·
1,405 Posts
You can click the square that says "Graph Limits" above the graph in REW to enter the Shack standard scale and you will have posted the graph correctly. Did you load the calc file for the mic after doing the soundcard calibration? This is can be overlooked sometimes when one is getting started, and it might appear so by looking at the graph. I think you should be getting output lower but it could be due to the calibration. You can also load it now if you didn't and click "IR Windows" - "Apply Windows".
 

·
Registered
Joined
·
25 Posts
Discussion Starter #13
You can click the square that says "Graph Limits" above the graph in REW to enter the Shack standard scale and you will have posted the graph correctly. Did you load the calc file for the mic after doing the soundcard calibration? This is can be overlooked sometimes when one is getting started, and it might appear so by looking at the graph. I think you should be getting output lower but it could be due to the calibration. You can also load it now if you didn't and click "IR Windows" - "Apply Windows".
I loaded the soundcard calibration if thats what you mean. Under mic tab it says NONE cut i did calibrate the meter.
 

·
Premium Member
Joined
·
2,620 Posts
Yes, graph is much better now. Looks like some EQ on the sub might help, but lets wait on that for now.

Can't tell if the levels are too low from this. What you are doing is setting a 75db reference for REW - that has nothing to do with maximum system volume. Even with Audyssey OFF it set and stored your channel levels when you ran the auto setup. If you want more sub output, increase the sub channel level on the speaker setup menu on the receiver. If you need to adjust the other channels to get more overall output, adjust them all the same db amount so that the relative channel-to-channel level stays the same.

When you get a chance, post a sketch of your room layout - where all the speakers are, where the listening spots are, etc. That will be important when deciding where to put room treatments.

If you haven't tried moving the sub around into different locations, that might help with the bottom octave and overall freq response smoothness.
 

·
Premium Member
Joined
·
2,620 Posts
One more thing - on the waterfall screen, click Graph, Frequency Axis Log/Linear. Linear will spread everything out and make everything easier to see.

thewire - looks like we are posting the same info about the same time. Great minds think alike:bigsmile:
 

·
Registered
Joined
·
25 Posts
Discussion Starter #19
Funny thing is the first graph is plotted without audyssey is set at -4 and the one that has audyssey turned on is at -9. After 15hz it just completely gives up it seems.
 
1 - 20 of 25 Posts
Top