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Question A basic introduction to frequency response graph?

Tautitan

Active Member
Hey guys, apologies for the beginner thread here. I’ve got some older gear which I’m hoping to upgrade but at the moment I haven’t got a lot of funds. So I’m left with trying to make sure I’m getting the best out of what I have speaker-wise (I’ve got a newer amp on the way).

I’ve got a pair of monitor audio bronze b1s hooked up to a temperamental Cambridge audio 540A. Using an iOS app and the built in iPad mic plus a frequency sweep from YouTube (low tech but free) I can get a rough idea about quantifying what I hear. The following are screenshots from the b1s followed by my dt770 headphones(the light blue section is the recorded max for each frequency):

2m64bpw.png

2py2v83.png


The DT770s curve is much smoother and more well controlled, which is what I’d expect. But where would I start to help out the B1s to get a smoother overall response? Looking at the graph also confirmed to me that on some songs the upper bass(as I understand it) is too pronounced and not something I like but is definitely there. The tone controls help the graph between about 40 and 80hz but not the hump after that which I guess is what I’m trying to reduce. Jamming a sock in the reflex port on the back and using the tone controls to regain some lost bass has helped smooth out the curve somewhat and sounds more pleasant.
 

BlueWizard

Distinguished Member
I think you need to understand that if you are not using Flat Wide-Band Calibration Microphones, you can trust the frequency response. You also can't trust the frequency response in the average room. It will be full of peaks and valleys.

Also, understand that not even the best speakers get truly FLAT frequency response, and neither to people necessarily prefer flat frequency response. It is reasonable try to average out, or smooth, abnormal peaks, but you don't equalize out what makes the speaker sound good.

The Bronze B1 are not huge speakers, and are going to have limitations especially on the low end.

Curious, how close were you mic'ing the speakers?

Also, how did you record your Headphones?

Steve/bluewizard
 

Tautitan

Active Member
Thanks for your reply Steve :)

I’m not necessarily trying to make it flat, there’s just an unpleasant resonating “woooom” (not really a recognisable musical sound) that I’m trying to get rid of that’s not there when I listen on my headphones :)

The iPad was left placed around a foot away from the speaker, directly in front and the headphones were measured by placing the iPad a few inches away from one of the ear cups with the other one covered.
 

andy1249

Distinguished Member
Here is a paper on using IOS devices for measurement.

http://www.sandv.com/downloads/1703smit.pdf

See the section on the built in transducers.
In short, not accurate at all.
Response varies with model and everytime an update is applied.
In addition the internal circuitry modifies the input greatly as its optimised for clear speech.

IOS can be used for accurate measurement, but not with the built in microphones and only with software carrying calibration correction curves for various versions of IOS.( not free...expensive).
 
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Ugg10

Distinguished Member
Just eye-balling the top graph is looks like a fairly typical commercial speaker response in a smallish room with a bit of bass enhancement and then a shallow slope toward the treble. However it looks like you have an 80hz room resonance that is then seen in harmonics at 240hz and 320hz, the 160hz seems to be damped out. 80-85 hz has a wavelength of 14-15ft, don't suppose you are playing the speakers along the length of a room that size (or a multiple of it). This room resonance is maybe what you are hearing. Does the sound you are hearing change as you walk about the room (changing you head height as well) ?
 

Tautitan

Active Member
Actually, the room is 13ft on a side... that’s a pretty dang close deduction from you, nice one :lesson:

I’m not at home at the moment to try the walkabout test but I’ll be sure to give it a try when I do; in the meantime I’ll read up on room resonance :)
 

Tautitan

Active Member
I gave it a walk around and it’s a little different at other spots than the listening position but not greatly so. I took delivery of a new amp yesterday, a used Denon 1912 and it’s completely changed the speakers. There’s more of... well everything. It supplies a much stronger lower end even from these little speakers and the hump I didn’t like has not disappeared but it is much better than before; I’d guess all this has something to do with the Audyssey calibration and MultiEQ that’s being done.
 

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