Neil’s
DIY Plate Amp Page
Note: you MUST read the fine
print at the bottom of this page before using these designs
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Circuit
#1: 25W + 25W amp with 4-pole analog
active crossover |
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Features |
4-pole LR crossover with frequency selected by plug-in resistor networks. Uses LM4766 for moderate output. Good low-cost plate amp circuit for high-end computer speakers. Analog input. Requires approx 40VCT transformer
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Schematics |
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PCB |
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Parts List |
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Photo |
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Hi-RES |
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Circuit
#2: Active crossover board |
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Features |
“Universal” active crossover board that is nominally a 3-way 8-pole LR crossover. Two of the 8-pole filters can be configured as independent 4-pole sections to provide more flexibility. The board also includes the Linkwitz Thor subwoofer EQ circuit to shift the poles for a closed-box subwoofer. I have extra boards that I will sell at cost—I’m not using this approach anymore (going with TAS3103 or TAS3004)
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Schematics |
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PCB |
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Parts List |
Excel |
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Photo |
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Circuit
#3: 50W + 50W LM3886 board |
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Features |
Just a basic 2-channel amp that can be used with the active crossover board or elsewhere. This board uses the ExpressPCB “mini-board” form factor so you can get 3 boards shipped to your door within 4 days for $59, or whatever it is that they charge. This board actually has a stupid mistake: the mounting screw for the LM3886 on the right gets obstructed by the filter cap. If you plan ahead you can work around that problem, but after I assembled this I was reminded of those ethnic-slur coffee mugs with the handle on the inside *DOH*. Requires an external bridge rectifier.
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Schematics |
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PCB |
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Circuit
#4: 50W + 50W amp with Digital
Crossover |
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Features |
Crossover is programmable from a PC parallel port using the TI DCT tool. Crossover data can be saved in the EEPROM for stand-alone operation. The TAS3004 has enough signal processing to provide a 14-pole crossover or else lower order crossover plus driver EQ. Typical application will use an 8-pole crossover plus 6 poles of EQ per driver. The sub-out uses an analog 2-pole filter with the frequency set by a plug-in resistor network
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Schematics |
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PCB |
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Parts List |
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Hi-RES |
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Plate
#1: “70W” |
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Features |
3mm aluminum with mounting hole
for a 70W 3” toroid such as the Chia Yu Co 21V/21V from Apexjr. The plate dimensions are 7.1” by 5.4”,
which provides adequate heatsinking for a single LM4766 or two LM3886 amps with
25-30V rails. For higher rail
voltages, use the 150W plate. |
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Design File |
GIF |
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Parts List |
Excel |
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Photo |
Hi-RES |
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Fine Print Section These designs may be used freely for any non-commercial application. They are placed here as a free service to the DIY community, as “as-is” snapshots of projects that I have done. These designs are not offered as field-proven circuits with all problems ironed out: they are intended to help other DIY’ers “jumpstart” their own efforts, and additional development and debug work may be required. There is no guarantee that the information here is up-to-date and error-free, although to my knowledge these are designs that work. Support Note You are on your own with these--I don’t have the time to assist in building or modifying any of the circuits here. I’ve got a demanding full-time job and I believe that my spare time is better spent working on new projects (which I will probably make available to others). I may answer a question or two, but I don’t want to get bogged down in supporting older designs. Your understanding is appreciated. Development Tools Download ExpressPCB from www.expresspcb.com Download Front Panel Designer from http://www.frontpanelexpress.com/ Obtain the TI development tools for the TAS3004 from support@ti.com ALE 5.2 for crossover development DCT 3.1 to interface to the TAS3004 from a PC |