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TOPIC: Re: Simple 4-Way System

Simple 4-Way System 8 years 10 months ago #3983

  • KAMIKAZE
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<strong>Drivers:</strong>
-SB Acoustics 26STAC
-Peerless 830813
-ScanSpeak 8535-06
-Peerless 830846

<strong>Speaker parameters: </strong>

Peerless 830846
Driver Properties
Name:
Type: Standard one-way driver
No. of Drivers = 1
Fs = 25.43 Hz
Qms = 10.67
Vas = 66.53 liters
Cms = 0.376 mm/N
Mms = 103 g
Rms = 1.56 kg/s
Xmax = 12.5 mm
Xmech = 18.75 mm
P-Dia = 212 mm
Sd = 353 sq.cm
P-Vd = 0.441 liters
Qes = 0.4
Re = 2.6 ohms
Z = 3.12 ohms
BL = 10.23 Tm
Pe = 175 watts
Qts = 0.39
no = 0.257 %
1-W SPL = 86.25 dB
2.83-V SPL = 91.13 dB

ScanSpeak 8535-06
Driver Properties
Name:
Type: Standard one-way driver
No. of Drivers = 1
Fs = 28.77 Hz
Qms = 3.24
Vas = 59.15 liters
Cms = 2 mm/N
Mms = 15.29 g
Rms = 0.854 kg/s
Xmax = 5 mm
Xmech = 7.5 mm
P-Dia = 135.9 mm
Sd = 144.3 sq.cm
P-Vd = 0.0721 liters
Qes = 0.69
Re = 5.9 ohms
Z = 7.08 ohms
BL = 4.87 Tm
Pe = 70 watts
Qts = 0.57
no = 0.197 %
1-W SPL = 85.09 dB
2.83-V SPL = 86.41 dB

Peerless 830813
Driver Properties
Name:
Type: Standard one-way driver
No. of Drivers = 1
Fs = 43 Hz
Qms = 9.26
Vas = 17.55 liters
Cms = 1.648 mm/N
Mms = 8.19 g
Rms = 0.243 kg/s
Xmax = 3.5 mm
Xmech = 5.25 mm
P-Dia = 105 mm
Sd = 86.59 sq.cm
P-Vd = 0.0303 liters
Qes = 0.28
Re = 6 ohms
Z = 7.2 ohms
BL = 6.886 Tm
Pe = 50 watts
Qts = 0.272
no = 0.48 %
1-W SPL = 88.96 dB
2.83-V SPL = 90.21 dB

Tweeter was not measured.


<strong>Amplifiers</strong>: LM3886 for WMT, and for SUB LME49830

Some photos and videos of DIY process:



Also photos are here kamikazeua.narod.ru/
















































Tunning process:











For compare I want to show some FIR filter system response:
This system filtered via PC and using FIR plugins and 7.1 soundcard. This CAN NOT be done with miniDSP. The sound of FIR filters is amazing, I wish miniDSP become with FIR filtering.




Problems with my system: small hissing noise from WMT, and 50hz noise from SUB, because of ground loop. All amplifiers in one case and my knowledges is too poor to fight with it. Anyway this project would be disassembled and sold.
Last Edit: 8 years 10 months ago by KAMIKAZE.
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Re: Simple 4-Way System 8 years 10 months ago #3984

  • KAMIKAZE
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ALso, I want to explain process to set up delays for drivers.
In this article www.hifizine.com/2011/03/refining-a-4-wa...speaker-minidsp-2x4/ we have some method like:
There are various ways of working out what to set the time delays to, but here’s a fairly quick and simple technique:
-Pick a pair of drivers, and place the microphone vertically mid-way between the centers of the drivers, and about a meter away.
-Turn off all channels except those two.
-Turn off the crossover filters for those two drivers.
-Set one driver to have a short (1 to a few ms, depending on the drivers) time delay.
-Run a sweep over a frequency range that is covered by both drivers.
-Look at the impulse response to determine how much the drivers differ from the specified time delay.

This is maybe ok, however this method gives me: 0.12ms for MID and 0.16ms for TWT. But I want to see what happens in reality.
To do this follow next steps:
- turn on only TWO drivers with filters(filter MUST be turned ON), for example MID and TWEETER
- place the microphone vertically mid-way between the centers of the drivers, and about a 20-25cm away
- Invert phase for any of driver
- do measurements of amplitude response.
- you may see a gap\pit on crossover point like this

- change delay for your driver to make this gap on crossover point the maximum depth.
- after you found optimal delay, back phase of one driver to normal.

After that you can do measurements and on the crossover point must be NO gaps, otherwise your delays are wrong. Also do not forgot to start tuning delay from WOOFER to MID. Typically only MID and TWEETER will have delays options.
For my system it's 0.12ms and 0.18 accordingly.

Yea, one thing: for miniDSP delays are +-7 mm, because of 48k sample rate. So if you change delay you "move" acoustic center of your drivers for 7mm.
Last Edit: 8 years 10 months ago by KAMIKAZE.
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Re: Simple 4-Way System 8 years 10 months ago #3999

  • KAMIKAZE
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SOme video play process :)
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Re: Simple 4-Way System 8 years 9 months ago #4019

  • devteam
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Well, for a "simple 4way system" that's quite some documentation you have! :-)

Thanks for sharing your project and experience.

DevTeam
miniDSP, building a DSP community one board at a time.
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Re: Simple 4-Way System 8 years 9 months ago #4027

  • joe3rp
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nice system!
I am a newbie on this site, I am interested in using the mini-dsp for a 4 way system, what spec of mini-dsp did you get to allow equalization, time delay and x-over for your system.
I plan a compression tweeter, compression mid horn, woofer and subwoofer. Thanks
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Re: Simple 4-Way System 8 years 7 months ago #4547

  • KAMIKAZE
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Thanks. 4-way advanced plugin.
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