200wrms stereo amp

[monkeytree]

i have looked on the net and have been unable to find a decent one with all the component values on it can any body help me plz?
thank you.

 

[Nigel Goodwin]

i have looked on the net and have been unable to find a decent one with all the component values on it can any body help me plz?
thank you.

You don't specify what you want it for?, but there are plenty of suitable circuits at https://www.ampslab.com/projects.htm.

However, you should be aware it will probably cost more to build one than buy one!. You can buy high power amplifiers for very little money these days!.

 

[monkeytree]

thank you nigel that amp will be suitable for my needs
i want to build the amp my self to get more expirince in building larger pieces(and i need a new amp anyway)
that website did not come up on my search

 

[monkeytree]

(to nigel inparticular)
for stereo mode does it just mean use two of the circuits? from the same psu(but with the 500VA rating)?

 

[Nigel Goodwin]

(to nigel inparticular)
for stereo mode does it just mean use two of the circuits? from the same psu(but with the 500VA rating)?

Yes, a stereo amp is just two mono ones, you can either use a double sized PSU, or two completely seperate PSU's (which is generally considered better).

 

[monkeytree]

why are two psus better?
power spikes/surges?
better balancing?

 

[Nigel Goodwin]

why are two psus better?
power spikes/surges?
better balancing?

Because it keeps the two channels completely seperate, which improves cross talk between the two channels. It also gives the potential for better reliability, if one channel dies then you may well lose both with a common supply, with independent supplies the good channel will still work.

From a monatary point of view independent supplies cost more, so I shouldn't get too worried about it!.

 

[monkeytree]

the psu requires 2 20,000uf caps but i cant get them would it be cheaper to put smaller ones in parralel
3 or 5 amp fuse?
i also need a good supplier of transistors;2n5551,bc639,tip30c,tip29c,mje340,2n5401,mj15003,mj15004

 

[audioguru]

I guess you can't build it if you can't get parts for it.

 

[Nigel Goodwin]

the psu requires 2 20,000uf caps but i cant get them would it be cheaper to put smaller ones in parralel
3 or 5 amp fuse?

It's common practice to put smaller caps in parallel in the PSU, and is usually better than using just a single larger capacitor.

If you mean the plug fuse?, then 3A will pass just under 750W - but if you're using torodial transformers there is a considerable surge as you turn them ON.

 

[monkeytree]

one last questoin what does the A mean?

 

[Nigel Goodwin]

one last questoin what does the A mean?

If you read the article on the website it explains it!.

 

[monkeytree]

arfter reading it through for the 4th time (i read it 3 times before) i am still incapable of finding any refrence to "A".
a link mabye? plz

 

[audioguru]

I think the resistor just is used for measuring the voltage at the base of the transistor without your meter's leads injecting much noise since this is a very sensitive spot.

 

[Nigel Goodwin]

arfter reading it through for the 4th time (i read it 3 times before) i am still incapable of finding any refrence to "A".
a link mabye? plz

It 'was' somewhere on the site, it's perhaps explained under one of the other amplifiers on the site?.

Anyway, it's simply an extra component used for a bridged amplifier configuration, whrer you connect two together to give 400W into 8 ohms, this is listed on the first page of the project.

Tut tut - Audioguru!, a little too much beer this weekend? :lol:

 

[monkeytree]

thanks all the parts should be coming tomorrow so i can check they all fit on the boards then i can start making :!:

 

[audioguru]

Oops, I forgot.
Of course the resistor can be used for bridging two amps together since it is the same value as the feedback resistor. :lol:

 

[monkeytree]

so to bridge it i link "in" "A" and "out"?
with mono input?

 

[Nigel Goodwin]

so to bridge it i link "in" "A" and "out"?
with mono input?

You have two amplifiers, lets call them 'master' and 'slave' - your input signal goes to 'master', on the 'slave' the input is grounded and point 'A' is connected to the output of the 'master' amplifier. You connect the 8 ohm speaker between the outputs of the two amplifiers.

Unless you have some specific reason for doing this I generally find it less than useful? - if you have a single 8 ohm speaker rated at 400W then it's fine!. However, this is probably not the case?.

A more usual situation (PA speaker wise), is that you might have two cabinets, each containing two 8 ohm speakers wired in parallel, this gives 4 ohms per cabinet, and the two amplifiers will give 2x200W stereo in to these speakers.

If you bridge the amplifier, you could then connect the two 4 ohm cabinets in series, giving 8 ohms, and producing 400W mono.

So you get exactly the same amount of power, into exactly the same speakers, but only in mono rather than stereo - and reduce your reliability as a single amplifier failure will result in a complete loss of sound, stereo is particularly useful for the extra redundancy it gives.