Power Amplifier schems and pcbs?

[tednet]

Hey there Recently, I got a custom made power amplifier combo (an active cabinet) for free. Well the thing is that the thing doesn't work and without a schematic I can't do anything... anyways... I was thinking of making some power amplifier, sticking some nice distortion pedals as pre-amps and bam, instant amplifier...

My problem is that I am not that good at making pcb's from schematics... so I was hoping someone has a pcb and layout alongside the schematic 

My task is to utilize the power supply - it has 25v, 32v and 72v. The 25v is linked to the fan...

I'll probably use the 32v for the pre-amps... just have to figure a way to make it 9v.. and yeah, give me your best power amplifier that can run on 72v

Any wattage will do really, but the more, the merrier The previous owner said that this thing was running at 220watts, so yeah, I am hoping you can give me atleast a 100watt power amp

PS If you have schems and layouts for complete amplifiers, not just the power amp, please feel free to link them, just know that my limit is 72v

[Minion]

What Kind of 72v is that..Is is +72 v or +36v,0v,-36v ?? AC or DC?? Do you know how many Va the transformer is? The simplest type of amp to build would be a chip amp , they are just like a very high power opamp and use few external parts and sound very good and can be built up to 100w a channel depending on the Chip you use... The problem most Chip amps are going to need a +/- Power supply , at least most of the ones that have a PCB design available ....

There are a few Discrete Power amps out there that run off of a single supply but going discrete isn"t necessarilly the best first Amp project as it does involve a lot more troubleshooting and set up to get working and arent then best sounding amps unless you go class A has it"s own problems....

Here are a few chips to look into, google them for datasheets...

TDA2030
TDA2040
TDA2050
LM1875
LM3875
LM3886
TDA7293

I have PCB"s designs for most of these Chips but they all Need a Dual PSU.....


Cheers

As for the Preamp , if you have 32v DC and your preamp uses just opamps then you can probably run them off of 32v DC as most opamps can handle a max of 30 to 36 v depending on the one you use , you will have a lot more output Voltage and headroom running off higher Voltages....

[tednet]

72AC

well it would be mighty nice of you if you could give me those layouts

I suppose I could find a way to make a dual psu.

Ps I was thinking of making this one http://europa.spaceports.com/~fishbake/amp/ca100.htm  or maybe this one http://sound.westhost.com/project27.htm . Sadly, I need pcb's for those :S

So yeah, could you give me the pcbs you can mail them to me at  tednet4wow[at]gmail.com   

[Minion]

At 72V ac None of those chips will work , that is over 100v DC and even if it was a dual supply 100v or 2x50v dc would still be too high , the highest voltage for any of the chips I listed would be 2 x 42v DC and that is for the TDA7293 100w chip and it can"t run on a single supply......

The next closest chip would be the LM3886 which is a 50w Chip that can"t run on any higher than 2x35v DC, it can run on a single supply of 70v DC but I don"t have a PCB a single supply version which is quite a bit different than the dual supply version .....

I think if you are determined to use that Power transformer you won"t be able to build a chip amp , you will need a dual supply of a lower voltage for most any chip amp , or a single supply of a lower voltage but I don"t have PCB"s for a Single supply version and the dual supply version can not be modded to work on a single supply and you can"t make a proper dual supply from a single supply for a high power amp as the virtual ground PSU trick you use with regular opamps doesn"t work properly with High power amps as the ground drifts to much .....

I think you should look for a different power transformer , one that is either center tapped or has a dual secondary....

TDA2030  14w - 2 x 14v AC 30Va (2 x 18v DC) PCB in Datasheet
TDA2040 20w - 2 x 15v AC 50Va (2 x 20v DC) PCB In Datasheet
TDA2050 32w -2 x 18v AC 80Va (2 x 24v DC) PCB in Datasheet
LM3886 -50w into 8 ohms- 68W into 4 ohms - 2 x 24v AC 100Va-(2 x 35v DC 8 ohms) -2 x 20v AC 100Va - (2 x 28v DC 4 Ohms)
TDA7293 -100w into 8 ohms- 2 x 28v AC 160Va -(2 x 42v DC) - PCB in Datasheet

These chips are pretty cheap , the First 3 can be had from anywere from 50c to $3 , the last 2 are about $10 each...

As for the Amps in the Links you posted the first one I have built and it was an terrorable amp...It suffered from bad crossover distortion and thermal runaway , awefull sounding and very unstable and basicly unbiasable...

The next amp I haven"t built but it is a good amp from what I hear, but it needs a true dual supply and would entail buying or designing and etching your own PCB and you will have hard time finding a PCB design for it....


Cheers