Home Theater Forum and Systems banner

1 - 20 of 27 Posts

·
Registered
Joined
·
22 Posts
Discussion Starter · #1 · (Edited)
Alright, just wanted to run some tests with REW before my sub gets in later this week. So, I calibrate the sound card which already gave me trouble. I had a hard time adjusting the output and input so that I didnt get clipping issues. Basically had to have the input almost off. (I am using a realtek onboard on my PC). This is what I got for my souncard cal:
soundcal.jpg


I took a measurement of the loopback to make sure it worked, and seemed fine to me?:
soundcardloopmeasure.jpg


Now, hooked up to my receiver and ran some tests. Here is a full range run:
fullresponse.jpg

And here is a low:
frlow.jpg



Now, here is whats bothering me. First off, it dies up top? Doesn't sound that way. Secondly, down low. Supposedly my L and R speakers are running "flat" to under 20hz? This is impossible. They have ok output to about 40, but basically nothing under 30-35. What is going on with these measurements? Could it be that I am using long cable runs from my PC to my living room? (I dont have a laptop).

Edit: Might want to add I am using a Galaxy CM-140.

Any advice would be appreciated.

-Tyson
 

·
Super Moderator
Joined
·
9,285 Posts

Welcome to the Forum, T! Congrats, looks like you got REW up and running just fine. :T

Unfortunately you didn’t give us enough information to answer your questions.


Now, here is whats bothering me. First off, it dies up top? Doesn't sound that way.
Measure one speaker at a time, point the mic at the speaker. Does your receiver have any kind of auto EQ / calibration function that you’ve utilized?


Secondly, down low. Supposedly my L and R speakers are running "flat" to under 20hz? This is impossible. They have ok output to about 40, but basically nothing under 30-35.
How exactly did you previously determine that? What kind of speakers are these? Once again, any auto EQ that could have enhanced extension?

Regards,
Wayne
 

·
Registered
Joined
·
22 Posts
Discussion Starter · #3 ·
Ill try measuring speakers one at a time when I get home from work.

I have a Yamaha RX-V765, so it does have eq. I tried with it on and off and it made no significant difference.

My mains are destination audio f300t's. They are rated to -3dB at 45 hz, and definitely roll off hard after that. At 30 hz, they have very little output. It is very easy to tell by ear.

Could the long cable runs be affecting this? Should I recalibrate the sound card using the long cable runs as the loopback?
 

·
Registered
Joined
·
2,604 Posts
It's conceivable the long cable runs affect the high end, but I wouldn't expect them to affect the low end... you could try running a scan (with the already produced soundcard cal) of just the cables and see exactly what they're doing to you.
 

·
Super Moderator
Joined
·
9,285 Posts

My mains are destination audio f300t's. They are rated to -3dB at 45 hz, and definitely roll off hard after that. At 30 hz, they have very little output. It is very easy to tell by ear.
Keep in mind that factory specs are not absolute. For instance, if you use large speakers like that in a small room, low freq extension will improve due to cabin gain. In your case it looks like extension is being extended from 45 Hz down to ~38. That’s not a huge difference.

Also, manufacturers have been known to be conservative with their specs, as it can get a more favorable reaction from reviewers and owners. After all, who’s going to be disappointed when they find that a speaker goes lower than was expected?

Also, keep in mind that the graph scaling is coming into play. The “low” graph, which stretches the horizontal scale, is being visually “nicer” to low end response than the compressed full range graph. But with either graph you can see that response drops at least 10 dB between 38 and 20 Hz. That’s a significant enough drop that render output at 20 Hz insignificant.

As for as the upper end, I can't say I've ever seen anyone post a full-range graph generated with the Galaxy meter, so I'm not familiar with what to expect from them.

Regards,
Wayne
 

·
Registered
Joined
·
22 Posts
Discussion Starter · #6 ·
Thats a good idea. Ill try that tonight before I take measurements of the L R mains by themselves.

One other thing, is it normal to have to turn the output volume down to half or less and the input volume to almost 0 in order to keep from clipping?
 

·
Registered
Joined
·
22 Posts
Discussion Starter · #7 ·
One other thing, at a few spots there is what appears to be a null such as at 200 hz in the low graph I posted. But, If I play a sine wave sweep from 180-210 slowly, there definitely doesnt sound to be any huge null like the graph shows. Is there any explination for this?
 

·
Registered
Joined
·
22 Posts
Discussion Starter · #9 ·
Ya, I was refering to the bass only graph. For that graph I ran from 0 - 500hz.

So, since the null is too small to hear, does it matter?
 

·
Registered
Joined
·
2,604 Posts
Which is why the monster behind you always wins!
 

·
Registered
Joined
·
22 Posts
Discussion Starter · #12 ·
Ok, so I ran a loopback measurement using all my cabling. Perfectly flat. So thats not affecting anything.

I reran the measurements for the left and right seperate and again with them both together. This time I left off the cal file for the cm-140, makes the top end look alot more realistic.

Left with 1/12 smoothing:
frleft112smoothingnocal.jpg

Right with 1/12 smoothing:
frright112smoothingnocal.jpg

And Both:
frleftandright112smoothingnocal.jpg
 

·
Registered
Joined
·
2,604 Posts
Looks to me like you're using less smoothing now than before, and of course a slightly different scale, so it's difficult to compare directly... performing the additional smoothing mentally, it looks like you still have a dropoff starting at 4kHz... more realistic doesn't necessarily mean more accurate... Are those iwth the Galaxy in the same orientation? (hor vs vert)? Are you using our generic cal file for the Galaxy? It was taken in the horizontal position.
 

·
Registered
Joined
·
22 Posts
Discussion Starter · #14 ·
The mic was positioned horizontally and and it was pointed at the speakers when I did the L or R by themselves. I didnt use the cal file for these graphs. When using the cal file I get a significant drop after 4kHz and I cant believe that its true. It shows ~11dB drop from 4kHz - 10kHz with the cal file and that for sure would be audible, but I don't hear a significant drop (or maybe I am naive?)
 

·
Registered
Joined
·
2,604 Posts
It's hard for me to say exactly without having all the graphs in front of me on the same scale and the same smoothing. BTW you can add/remove the cal file after the fact.
It's possible you need a custom cal file for that mic, that the generic cal file doesn't fit your particular one very well in that range. Was it the generic one you used?
 

·
Super Moderator
Joined
·
9,285 Posts

I didnt use the cal file for these graphs. When using the cal file I get a significant drop after 4kHz and I cant believe that its true. It shows ~11dB drop from 4kHz - 10kHz with the cal file and that for sure would be audible, but I don't hear a significant drop (or maybe I am naive?)
I would agree that something’s amiss. The Galaxy calibration file shows that the meter is pretty well flat out to 8kHz. So with or without the calibration file you shouldn’t be seeing a drop starting as low as 4 kHz, especially one as serious as this.

Really, the best way to ensure accurate full-range measurements is with a custom-calibrated ECM8000 or EMM-6 mic...

Regards,
Wayne
 

·
Registered
Joined
·
22 Posts
Discussion Starter · #17 ·
Thanks for all you guys help. I'm not too worried about the upper range, it sounds good to my ears :) When I get my sub in I will repost my bass measurements.
 

·
Registered
Joined
·
22 Posts
Discussion Starter · #18 ·
Got my Empire in today and so far really liking it :) Now that I got some time I am moving it around and taking measurements. There are two places that I have found so far that will be ok I think, but the front right placement might be questionable with the wife. I will find out tomorrow :)

Here is the Front Right which I think looks better and easier to EQ:
empirefrontrightnoeq.jpg

Here is a better spot as far as layout goes, we will call "corner":
corner8.5ftdistnoeq.jpg

And a overlay:
cornerandfrontrightoverlay.jpg

By the way, these are all with the mains running.

Do you think I can get away with the corner? Or should I try to convince my wife that frint right is ok :)

Gonne keep messing with positions before I start EQ'ing.
 
1 - 20 of 27 Posts
Top