Serious PC Speakers

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Gerhard

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Ok so here is a project that I started a long time ago because I had some of the parts. I spend so much time in front of the computer so I thought I'd build me some serious PC speakers.

Drivers are:

Peerless 830964 4Ohm 6.5" subs
Hi-Vi B3N 3" full range magnesium/aluminum alloy mids
Seas 19TNF 0.75" tweeters

I originally wanted to use just the Hi-Vi's as full range drivers based on one of Zaph's designs but I did not liked what I heard - the tops were not great. AT ALL! So I thought I'd throw in a proper tweeter and I am glad I did :D.

The amp I built - what is a serious set of PC speakers without a serious amp? - is configured as follows:

Subs are driven by Rod Elliot's P3A 2 x 100W amp and actively equalized by an 8 band EQ between 25Hz and 125Hz (Rod's P84). I incorporated Rod's P88 preamp into a preamp/crossover board of my own. The sub is crossed at around 300Hz/12db with a 36db high pass at 25Hz. The satellites naturally go from 300Hz up.

The satellites are driven by Rod's P19 50W LM3876 based chip amp.

The preamp/crossover board also includes 180 degree variable phase control with inversion switch and balance control. I included subwoofer volume control that is relative to the system volume control.

Also included is a protection and muting circuit (Rod's P33 - what can I say, I respect the guy's work!) with relays for all outputs.

A 25-0-25 300VA toroidal transformer provides +-35V rails to the amplifiers. A separate regulated power supply with its own transformer powers the rest of the circuitry.

I built the amp into an old Proton AM-455 case. I used the Proton's heat sink for the sub amps as well as its Alps volume pot and power switch.

For the satellites' crossover I used a conventional 2nd order low pass filter @ 3.8kHz and a 1st order electrical high pass filter with a 2nd acoustic target for the tweeters. I added an inductor to take care of some upper frequency rise. A 30 Ohm resistor brings the tweeter response in line with the mid range.

I am thrilled to bits with the outcome ;D ;D

Here are a few pics of the final result.

Sub
28032010010.jpg


Satellites
28032010011.jpg


Amp top
AmpTop.jpg


Amp back
AmpBack.jpg


Mid response
Mid.png


Tweeter response
Tweeter.png


Modeled response
TimeDomain.png


Crossover
XOverSchem.png
 
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