I'm taking the plunge!

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Hi Everyone,

I have decided I will make an audio system for my bedroom, consisting of a pre-amp, and a power-amplifier. My plans for the pre-amp include an electronic equalizer and display system (VFD) driven by a PIC, some op-amps, and some digital pots. The power amp will also have a PIC-driven display showing temperature, rail voltage, and current, as well as a driven power (W) measurement.

Anyway, low noise op-amps are a must for this application, as well as low distortion. What would you all reccomend? I am using them as filters to seperate the bands for my EQ. I then plan to do a mixing amplifier to re-combine the signals for output to the power-amp. Any other ideas besides op-amps?

For the power-amp, I will be using a front-end a friend of mine created (he used to work for Soundstream Audio, he a longtime audio fanatic) and a MOSFET power stage. I plan to run 50V rails from a ~35V transformer, and am having a hard time finding good MOSFET's in a complementary pair for the high and low sides.....many P-channel have quite high RDS or too low a VGS for the application. Any reccomendations here? I would like to keep the 50V rails to keep that power, I don't want to drop them. I will run true class A despite the heat and inefficiency, I will use a large heatsink and possibly some really quiet fans.

I will be designing and manufacturing a PCB, I have alot of experience in PCB design so that is an "easy part." I also want to have faceplate made for my units, and have selected Front Panel Express to do the job so far, does anyone know if they make good quality panels? Are there any other options? It seems like it will only cost about $60 to have a custom 18" X 12" X 4.0mm panel fabricated for my power amp, and around $40 for the 18" X 6" X 4.0 mm pre-amp panel, including display cut-outs and holes for things. I will either etch the PCB myself or have it made through a board house.

So, what do you guys reccomend for my pre-amp (no real design plans yet)? Where can I get good toroidal power transformers? I am looking for a dual secondary, 35V, 13A+ unit. Any thoughts or comments?

I have Multisim Professional to run computer simulations and EWB Utiliboard for my layouts, so I have a capble software package. Also have some test equipment here for trouble-shooting, an O-scope and more. I want to do things as well as I can here.....


Thanks in advance!

-Matt
 
Hi Guys,

Sorry to take so long to reply. I went to the exicon and profusion sites to look at the FET's, yes. I do not understand if they offer the complementary N and P channel devices? I am looking for a TO-247 or larger case (but not TO-3) if possible for power dissipation.

The hardest things for me to find so far are those FET's for at least +/- 150V (to be safe- I want to run 50V rails) with a low RDS so I don't need dozens of them.

I have searched online for the power transformers, and came up with several options. I do have a question though....Do you think any of these companies would offer a "student discount"? Many smaller companies for other electronic stuff do offer such discounts, I wonder if a transformer place might do the same thing. How would I best approach this? FYI I am a high-school Junior.






Thanks,
Matt Aurand
 
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