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Wanting to Build A Very simple SS circuit of about 30W

Started by vmd1, September 23, 2017, 11:50:18 AM

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J M Fahey

May be wrong but what I saw is a single channel 30W Class A amplifier, 2 required for Stereo, plus larger power transformer and *huge* heatsink, maybe a fan too.
Not too guitar friendly.  :(

vmd1

The amp I first put a link up for is a class A mono-block, a circuit designed by Jean Hiraga. It is a "Hi-Fi" type circuit. However, I have since abandoned using this circuit because heat dissipation will be impractical, with the size restrictions I have to work with. I could use a fan, but this complicates things more than I wish to for this project. Also, from research I have since done, almost any power amp can be used for a guitar amp, as long as you implement a preamp stage that shapes the tone, and provides a correct input impedance for a guitar.

vmd1


J M Fahey

Excellent choice.
You will have 20W instead of 30, excellent sond, for about 1/4 the size, weight and cost :) 

vmd1

Regarding the power supply design... If I need roughly 25v for the lm1875, and 9v for the jfet preamp stage, what is the best way to design the power supply? I was thinking using an 18v transformer for the 25v power amp voltage, and then having a linear dc regulator that draws off of the filtered +/-25v dc and drops it down to about 9v and putting a capacitor filter network right after the linear regulator, which then goes to the preamp circuit... or i could use a 6.3v transformer for the preamp and keep both power supplies completely separate... any thoughts? 18v A/C rectified and smoothed is about 25v D/C and 6.3v A/C rectified and smoothed is about 9v D/C.

If I use a linear DC regulator, I could save on the amount of ironware I would have to buy, and also need only one rectifier. The main question I keep thinking of is: Will a linear DC regulator introduce noise into the circuit, even if I filter its voltage output with caps before connecting to the preamp circuit?

I'll add for reference the regulator type I'm thinking: http://www.ebay.com/itm/DC-DC-4-2-40V-to-3-3V-5V-6V-9V-12V-24V-Buck-Step-Down-Converter-Linear-Regulator-/322365124189?

J M Fahey

Preamp consumption is nil, does not justify its own separate supply.

Get 9V with a reguator or simply a resistor-zener-capacitor net.