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Found this link:

Acoustic Power Lab :: Home

describing sound processors from the Acoustic Power Lab. Does anybody have any practical experience with it?

According to the manufacturer this device has won different competitions in Europe. Looks promissing, but seems to be lacking some smart features as bluetooth, crossover, etc. As I understand the philosofy of the company - to produce a really audiophile unit of minimalistic design comprising only what is neccesary to produce high sound quality.

The „Pro Sound News Europe” trade journal lists SPFR (sound/acoustic power frequency response) correction technology as one of the three leading innovations in the field in Europe. The invention was awarded the Excellence prize by the AES in New York, 2007. In 2010 the author developed an alternative technology version for application in car audio systems. The car equipped with that solution earned “best sound” at the Salzburg EMMA-2012. Latest news – 2 first places at EMMA Eurofinals in SQ and MM in March 2014.

APL1 is a FIR based 2 channel equalizer with 4096 coefficient FIR filters per channel allowing curve resolution of up to 6Hz. It is capable of creating any arbitary Amplitude Frequency Respone (AFR), Phase Frequency Response (PFR) or Delay Frequency Response (DFR) suitable for very detailed and accurate corrections and equalization in critical applications such as studio monitors, headphones and car audio systems.
USB connection allows the upload of correction filter files to APL1 unit even in the middle of a live performance without any disturbdances in sound. The unit can optionally have a 16 preset memory accessible trough an external, freely placeable rotary switch, excellent for car audio installations.

Specifications:
• Number of processing channels: 2
• Resolution: 48kHz/24bits, digital input - uptil 96kHz/24bits
• Frequency resolution of correction curve: 6 Hz, 4096 coefficients at 24 kHz bandwidth
• Inputs: 2 analog balanced, digital - SPDIF coaxial and TOSLINK optical, AES/EBU on order
• Outputs - 2 analog (XLR balanced), digital - SPDIF coaxial and TOSLINK optical, AES/EBU on order
• Input/output analog signal max levels: +10dBu (can be changed on order)
• Analog input/output connection types: RCA or XLR
• Analog input impedance: 10 kOhm
• Analog output impedance: 150 Ohm
• Common mode signal rejection (CMSR) of analog input – 90 dB
• Dynamic range (analog input/output):104 dBA.
• THD (analog input/output): 0,07%
• Signal delay: 1.6 ms (analog input/output), 2.4 ms (digital input/output)
• Control and upload interface: USB
• Interface computer system: Microsoft Windows
• Power: 6.5 to 16 V DC, 3.5 W.
• Dimensions 15х20х5.3 cm.

As I understand, it is not on ebay yet, but could be purchased from the company link. Any ideas?
 

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It seems to be a right time to exchange practical experience of APL1 application as more and more SQ-enthusiasts became an owner of such a device.
 

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It seems to be a right time to exchange practical experience of APL1 application as more and more SQ-enthusiasts became an owner of such a device.
Recently I have installed 3-way system in my car. It took less than one hour to test and tune it. Now I am enjoying music :) instead of a nightmare of the time consuming tuning process. Really very powerfull device!

SO right left comp_target.jpg
This is my front before tuning. Orange line on this first pisture - desired target curve.

Right_Left_2.jpg

And finally - result of tuning by APL1 sound processor. Deviation between the front channels is below 2 dB, which might be considered as acceptable. Comments?
 

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Looks good Alex........ still in the process of setting up/tuning mine. Replaced my tweeters and awaiting a new amp for my midrange. Hopefully I'll have it all setup soon.
Did you leave the setting at -6db for the upper and lower ? Also which wave did you use 50 100 or 200 ?
 

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You'll have problems above 7kHz, if you will use -6dB limitation. 80 and 180 Hz have also problems due to this limit (look on the target curve). With your tweeters I would rather recommend -18kHz. Wave 50 is fine. I used to switch it only when connecting sub and woofer, but this will be not so accurate at higher frequencies.

Remember to use a calibration file for your mic. It has changed the whole picture drastically in my car.
 

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I replaced my pdx5 powering my mids for a mosconi one (230 x 2) ... did a workshop sweep at lunch today

[/URL][/IMG]

my tweeters fall off like rocks, not sure if its them being off axis in the doors or what....
 

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Where exactly your tweeters are placed?
 

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Seems OK. I had tweeters in almost the same position, but directed almost back. Never had issues. What about this stock grid? Couldn't it give off-axe problems - looks rather tight. Let APL1 solve this problem with its powerfull equalisation. Looking forward to see corrected curve :)
 

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Well the tweeters have grills and the speaker pods have grills as well... So double grilled.. But I think I tried with the pod grills off and it didn't make much of a difference I'll try remeasuring to make sure...
 

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Some new test results obtained with the help of TDA-software from the Acoustic Power Lab are presented below.

First - Response of the left channel to the sweep signal.

left3d 300ms.gif

How APL1 solves minimum phase problems could be seen from the next pictures:

Before (without APL):




Right channel_no APL1.gif

And after APL1 was switched on.
Right channel_APL1 on.gif

Be aware that I am using a passive crossover for the front speakers, so time alignment bwtween tweeters, mids and woofers is not possible by ordinary means.
 

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I have played with the tda software some.... Not sure if my laptop/mic is wacky or the surrounding noise is interfering. But I can take a measurement then take another right after and the results are very different... This is making no changes just doing another sweep.
 

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Im not sure but if I'm not loading the .fir files correctly or what but after measuring and using aplconfig to send the files to the unit before and after measurements are the same... unit has power, led indicators work and it is detected when I connect to it to load the files........
 

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I have played with the tda software some.... Not sure if my laptop/mic is wacky or the surrounding noise is interfering. But I can take a measurement then take another right after and the results are very different... This is making no changes just doing another sweep.
I do not think it is a problem with the noise level, otherwise - you could increase the output volume. TDA test is generally rather sensitive to the position of measurement instrument (mic). It should be firmly mounted at the listening position. It is hard to achieve with the laptop in-built mic. I use omnidirectional mic Behringer 8000 - calibrated. Now I can produce almost the same results during TA tests. Apply averaging afterwords. It works for me.

But again - trust only your ears and you would be able to select the most suitable variant of time alignment for your system.

Another question - internal sound card of a laptop. They used to be awfull. Mine (DELL) had deviations up to 8 dB. It is not acceptable at all for APL Workshop soft.
 

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Im not sure but if I'm not loading the .fir files correctly or what but after measuring and using aplconfig to send the files to the unit before and after measurements are the same... unit has power, led indicators work and it is detected when I connect to it to load the files........
Strange. Something is wrong.

What about bypass? Is it off? Never experienced with such a problem. Please be sure you are using correct files. Check that you use the same channel (out of 16) for uploading and listening the results.

To check connection between the device and laptop (aplconfig) try to load "mute" for both fronts. Let say - to the channel "0". No sound shoud output if everything has been done correctly. The "mute" preset will be usefull in many cases in future (f. ex. tuning of subwoofer, ...).

During the upload procedure you have a possibility to check the window below of aplconfig. It shows current info: connected, done, etc. Very usefull.
 

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Heres a sweep I took the other day of my system...

[/URL][/IMG]
If you are using mp1 as a target curve, it should not roll-off higher than 7 kHz. (Orange curve). Please check the limits under the test -6dB is not enough in your case. Could you send the inverted curve - EQ correction?

Again and again - omnidirectional mic with own (not generic) calibration file. It is critical.
 

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No I have the limits set for -18 low and high....... yes I have mp1 set as a target, its not showing to have cut the middle at all and to of boosted the high end



this is taking a measurement, which is the green line, applying the fir file for that measurement then taking another measurement which is the yellow line...
basically its not doing any sort of correction
 

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I mean all you should do is with aplconfig specify the left/right fir files for the measurement and then hit write to device correct ? If your not doing any correction in the way of peq... I havent been selecting a preset just sending the files to the apl1 ... is that the issue?
 
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