How can see in a REW measure when a single cycle 400 hz burst have on 2. positive (overshoot peak) more level than 1. positive peak. seem room problem

[user44455555]

I mean seem no room problem. I measure 1.5 cm away. and the focal alpha 65 with the carbon fibre(they call it slate fibre) woofer/mid have this problem not. Both are 6.5 inch speaker measure on same day on same stative position and 1-1.5 cm near. the focal soiund amazing and is on other level of 6.5 inch speakers woofer mid, but i see there can be much more enhance. i test with a transient enhancer in range 150-500 hz and i notice more clarity and punch which is then exactly on headphone. the bass feeling reach from 150-200 hz

there can calc and see that when measure 1.5 cm away and the nearest wall(desktop) is 40 cm away (which is 80 cm because sound need go to desktop and back) then level is 35 db less. so the room seem not the problem of this large overshoot of the Kali

Sound level distance damping decibel dB damping calculation calculator change distance versus sound level apps reduction drop dissipation SPL sound transmission loss free field loss sound and distance - decrease drop fall sound over distance versus d

Sound level distance damping decibel dB calculator calculation change distance versus decibel dB decibel sound level apps drop dissipation SPL sound transmission loss damping calculation loss sound distance sound reduction free field decrease fall drop attenuation sound over distance versus dB...

www.sengpielaudio.com

is there a way in REW software to see if the overshoot is larger as the signal ?.

the mesaure tone 400 hz. I test in DAW. signal is not very loud. only around 65 db at 1 meter. on top the 52 mean seconds. and scale is that 1 vertical line is 1 ms

Kali LP6 1. wave result

Foal Alpha 65 evo

superlux 686 evo put on desktop and measure in the middle of system 1.5 cm away. distance to desktop is 7 cm then. the overshoot can maybe larger because of reflections. even if not the headphone is a cheap model and cost around 30 $ and have best 1 positive peak level in my compare

the burst measure tones can download in this message and are bar align. they contain 100 hz, 400 hz, 800 hz , 1.4 khz, 2 khz, 3.5 khz. tweeter test i have not add, tweeters are much better. the strange thing is the kali do less overshot when test 800 hz or 1.4 khz. close bassport i test on all speakers. does not help . on 100 hz speakers do more overshot also the headphone. but the headphone is always much better

thats strange. I thought overshoots are more when come more near the maximum frequency of a system. that there on low frequency are so much problems in speakers is really bad because the room have longer reverb and so reverb the overshoots too

 

[John Mulcahy]

You can use the signal generator and scope, or use trace arithmetic to multiply the burst signal (imported as audio data) by a full-bandwidth measurement of the system. After importing the burst set the IR left window to rectangular to avoid changing its shape. Trace arithmetic can be used to view the response to any signal.

Single cycle unwindowed bursts have high bandwidth, so the result will be affected by the response of the driver far from the burst frequency. Using a windowed burst narrows the bandwidth, the plots below show the frequency spectrum of a Blackman-Harris 4-windowed single cycle at 400 Hz and an unwindowed single cycle at 400 Hz.

 

[user44455555]

I try the osciloscope in REW but i did not find a invert button osciloscope mostly have. there are active speakers that output diffrent polarity. for example the JBL 104 output invert. maybe invert buttons can add for each channel ?

I did not see and read not in manual how can enable channel 2 or channel 1- channel 2. the greyed buttons can not click. I get in mind, there need the pro version for this feature right ? . it is not important to have more inputs only important to see the original signal in osciloscope too. maybe it can then show for channel 2 the output signal of oscilator ?

With the trace arithmetic i did not understand how this work. look for videos REW trace arithmetic i did not find on. maybe there is somewhere a step by step instruction or a video ?

 

[John Mulcahy]

Scope CH1 is the input selected for measurement, CH2 is the input selected for ref.

On the All SPL graph click the trace arithmetic button.
Select your imported burst data (with its IR left hand window set to Rectangular) as measurement A.
Select your full range driver measurement as measurement B.
Select A*B as the operation.
Click the Generate button.
On the A times B result set the IR left hand window to Rectangular.

You can view the impulse response of the result to see the shape of the response to the selected burst. Here are examples for rectangular and BH-4 windowed single cycle bursts for a speaker measurement. Note the difference made by the bandwidth of the burst when it is not windowed.

This is the response of the example speaker measurement used.

 

[John Mulcahy]

I try the osciloscope in REW but i did not find a invert button oscilloscope mostly have.

You can set the Math channel to show -A (CH1 inverted) or -B (CH2 inverted).

 

[user44455555]

can see in screenshot ch1 is set to same input as channel 2 because i have not choose a loopback. the loopback channel can change in preferences but the scope input CH 2 is only change after quit and restart REW , now i can use channel 2 too