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Discussion Starter #21
Done with the build. Here's pictures of the other pod and some tuning. Sounds pretty good. Center image is great, depth pretty good, some slight rainbow effect on some songs. I am crossing at 80>>430Hz/24dB. Some annoying modal issues at 90 and 240Hz I can't fix, bringing the sub that high makes it audible way up in the lower midrange being limited to a 4th order lowpass. Overall an enjoyable system for my daily driver. I decided I will continue with my Passat again soon. I gotta make a bike and ATV ready for summer first... then you can expect some updates to that build again. Since I got access CNC-equipment now I'm planning some fancy stuff...







Had to send output from the measurement programs via a bluetooth transmitter.



Android app, it has 10 band parametric EQ per channel except sub which has 5 bands. dB setting is in 1dB increments which could be better but frequencies are freely adjustable and can be "stacked" on other bands. Q values from 0.3 to 9.9. It has LP/HP crossovers with 6/12/18/24dB slopes. T/A with 15ms (I think) delay. Gain settings with 0/180deg swap, mutable channels and a noise threshold mute thing if you're using OEM inputs. Unlimited presets basically since you can save to phone. Decent amp for the money.







I used APL workshop to measure the sound power response, imported the response into RoomEQ, used the auto EQ feature to give me filter settings. Worked fine. APL Workshop is far more accurate than "normal" measurement methods above the modal range (300Hz+). It ALWAYS gets it right on the first attempt, no fiddling around afterwards. I actually tried the old "RTA pink noise method" and sweeps to compare. Pictures in next post.
 

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Discussion Starter #22 (Edited)
Here's measurements from tuning the system. There is a dip in the response around the crossover, this is due to the falling power power response of the midrange driver and higher sensitivity of the tweeter. This could have been fixed with an L-pad, but I got EQ and didn't wanna make the crossover make complicated than needed. The rising response in the lower midrange is car acoustics, it's not there if you open the doors.







Same measurements imported into RoomEQ and overlayed.



Didn't measusre the system again. Verfified with bandpassed correlated pink noise that all bands were centered. Simply used RoomEQ to produce filters for me. Pulled down the sub to increase bandwidth, can't remove the filter at 100Hz since it's built in the amp.



Here's an example of APL workshop (purple) vs RTA spatial average measured (blue/orange) around the head while sitting in the car. As you can see they produce similar but not the same results. APL is the method that does it right. I've verified it time and time again with listening tests. 1/24oct smoothed.



Oh and here's a bonus... IMD testing to the left midbass with the door open, measured in nearfield at 2V input (around 90dB/1m). As you can see there's not much higher than 1% across the spectrum. I really like these programs that Raimonds push out.



Alright... see you in my main build thread next time. There might be some update in the future to this if I change anything, until then...
 

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I wondered how good the Axton would be, I've been looking at the Emphaser 6/8 channel (I believe the companies are related, app and designs similar or identical)
 
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