3-5 watts classA amp

adason · 26th November 2007, 01:13 AM

I was bored over the holidays so I made small amp. Just for fun. From spare parts. Its from this site:

http://www.redcircuits.com/Page80.htm

Sounds good. Definitely worth exploring.

ed

davidallancole · 26th November 2007, 01:43 AM

This amp is similar to the JLH Class A amp.

http://www.tcaas.btinternet.co.uk/jlh1969.pdf

Minion · 26th November 2007, 08:18 PM

Hi, I have looked at that circuit before but never got arround to Trying it because I have had problems with many of the circuits on that site.....But now that i know someone else has tried it I am more inclined to build it.....

I just quickly did up a PCB design for this amp and was wondering if someone could look at it and see if I made any Mistakes....

I used the Pinout for the Output transistors after the Tip transistors as that is what I have on hand (B,C,E) and I used the pinout for the other Transistors as a BC560 which I have...

The PCB is 2in x2.1in....

Thanx

PS, I also used an Input resistor for the P1 pot to set the Input impedance...

adason · 26th November 2007, 08:23 PM

I just want to add one more information. Amp prefers regulated supply. It works with both just fine, but you need way too much capacitance for unregulated supply to be hum free. Than it kinds of defeats the purpose of cheap amp, does not it, if you have to use tons of filtration.
ed

Minion · 26th November 2007, 08:55 PM

Filtration is cheap.....I have a Box full of 10,000uf caps that I got for $1 each, also with a LM317 regulator and a cheapo Pass transistor you can make a regulated supply that supplies serveral amps of Current.....

adason · 27th November 2007, 12:08 AM

Quote:

Filtration is cheap.....

yes and no....
I was testing unregulated suply, started with one 27000 uF, big hum, obviously its simple classA amp, that is expected. I needed to add six (6) of those 27000 uF caps. Now that is not a cheap solution.
On the other hand, if you use just 5000 uF before, than regulator, and 1000 uF on the output, it will be much less money.

ed

Zen Mod · 27th November 2007, 12:12 AM

or 27KuF , then cap multiplier , then 27KuF

that's even better than reg

adason · 27th November 2007, 12:22 AM

Hi Choky,

that would increase voltage. I started with the voltage I wanted, 22-24 V. Just wanted to filter it.

By the way, when you use multiplier, does not that reduce current capability? You know, each time you double the voltage, you half the current?

This amp takes 1.5A.

ed

Zen Mod · 27th November 2007, 12:29 AM

Quote:

Originally posted by adason
Hi Choky,

that would increase voltage. I started with the voltage I wanted, 22-24 V. Just wanted to filter it.

By the way, when you use multiplier, does not that reduce current capability? You know, each time you double the voltage, you half the current?

This amp takes 1.5A.

ed

not voltage multiplier ;

cap multiplier .......... google for it or go to ESP site and read tutorial

adason · 27th November 2007, 12:37 AM

I see, Choky, great. I was in Elliotts page. I got it.
ed

27th November 2007, 12:12 AM	#7
Zen Mod diyAudio Member Join Date: Jan 2003 Location: ancient Batsch , behind Iron Curtain	or 27KuF , then cap multiplier , then 27KuF that's even better than reg __________________ my Papa is smarter than your Nelson ! tnx to clean thread ; Cook Book ; PSM LS Cook Book ; Baby Diyaudio FORUM ; BAF Forum & Gallery;I'm dumb

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26th November 2007, 01:43 AM	#2
davidallancole diyAudio Member Join Date: Nov 2005	This amp is similar to the JLH Class A amp. http://www.tcaas.btinternet.co.uk/jlh1969.pdf

26th November 2007, 08:18 PM	#3
Minion diyAudio Member Join Date: May 2006	Hi, I have looked at that circuit before but never got arround to Trying it because I have had problems with many of the circuits on that site.....But now that i know someone else has tried it I am more inclined to build it..... I just quickly did up a PCB design for this amp and was wondering if someone could look at it and see if I made any Mistakes.... I used the Pinout for the Output transistors after the Tip transistors as that is what I have on hand (B,C,E) and I used the pinout for the other Transistors as a BC560 which I have... The PCB is 2in x2.1in.... Thanx PS, I also used an Input resistor for the P1 pot to set the Input impedance...

26th November 2007, 08:23 PM	#4
adason diyAudio Member Join Date: Nov 2004 Location: home sweet home	I just want to add one more information. Amp prefers regulated supply. It works with both just fine, but you need way too much capacitance for unregulated supply to be hum free. Than it kinds of defeats the purpose of cheap amp, does not it, if you have to use tons of filtration. ed

26th November 2007, 08:55 PM	#5
Minion diyAudio Member Join Date: May 2006	Filtration is cheap.....I have a Box full of 10,000uf caps that I got for $1 each, also with a LM317 regulator and a cheapo Pass transistor you can make a regulated supply that supplies serveral amps of Current.....

27th November 2007, 12:22 AM	#8
adason diyAudio Member Join Date: Nov 2004 Location: home sweet home	Hi Choky, that would increase voltage. I started with the voltage I wanted, 22-24 V. Just wanted to filter it. By the way, when you use multiplier, does not that reduce current capability? You know, each time you double the voltage, you half the current? This amp takes 1.5A. ed

27th November 2007, 12:37 AM	#10
adason diyAudio Member Join Date: Nov 2004 Location: home sweet home	I see, Choky, great. I was in Elliotts page. I got it. ed

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