Searching for an Amp Projekt for +-50V

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Hello

I had days searching on the forum-search, I have found a lot but nothing completely satisfying.

I am searching for a simple poweramplifierprojekt that is stable at a voltage of +-48V. Singlesided Pcb-layouts should be availeble.

Power is is limeted with the supply voltage, somthing about 100W into 8ohm should be Ok, more or less is no problem.

So, if someone has designed a small amplifier like this for himself and wants to share it, please feel free to do it!

Thank you very much for your answers ! Though this might be a question which has been discussed many times.

greetings
Black
 
please help, still searching a amplifier projekt working with +-48V DC

Hello

I'm still searching, aftel all I noticed that the red Circuits-desing needs a preamplifier I decided to search again.

Please give me some advice wich projekts, apart from the leach amp are suitable, any power rating, either with or without PCB.

Thanks a lot!

Black
 
I wouldnt start with letting power supply decide what amplifier to build.

Here is a nice project,
well documented with schematics, PCB and building description.
I think very few of us would be disappointed with this DIY amplifier project.
When designing this amplifier I put up the following requirements:

Req1: The amplifier must be cheap

Req2: The amplifier must be reliable

Req3: The amplifier must sound fairly good

Req4: The amplifier must be easy to build

Try something simple for a change

:smash:
 
Hi Black Chicken,

If you're putting in the effort to build a power supply, provide heatsinks, and house the lot, why not build something a good measure above the average -

http://www.diyaudio.com/forums/showthread.php?s=&threadid=65286

Or check out my website -

http://members.dodo.com.au/~gregball/guru_004.htm

This has been hailed as the first really new design in decades! It's fully complementary to minimise high order distortions and will get you more power and sheer performance from your given power supply. That's why it's Patent Pending.

Cheers,
Greg
 
thank you!

Hello,

This is not my first power amplifier or electronik work at all.

I built a poweramp about two years ago, it worked really well at +-30V, than I started building a enclosure and a Powersupply for the amp that was constructed for +-50V, so I went for +-48V with big caps and good parts. But then The amp started to get instable at 48V one Worked, one not.....I never got this one to work at +-48V.

So now I'm searching a Amp-design to finish the amp and to use the expensive Parts left over by the old design (enclosure, transformer)
---------

The 25W amp looks really good, I do like these designs a lot, thank you very much for the link, maybe I'll build it in the future, just for fun.

--------

Yeah the symasym is a great design too, but I do need something to cope with 50V, though I dont really need the Power giver through the voltage.

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Jaycee: nice shematics, wich one Is more reliable in the buil, has one of them been build already succesfully?

Wich of these do you prefer?

I'd like to try the Mosfet-Build with 1 Pair of IRFP240/9240, because I dont need the RMS power all the time (home listenig, not PA use)
Do I need to Change something? Is the amp able to drive these fets?

thank you very much.

-------------

Guru: also great designs, but living in Germany I am searching for a free projekt, thank you very much for your advice.

any other suggestions are welcome!

Black
 
hello Quasi

Yes I did already read your thread, but I wasnt sure If the amp woul work at this low Voltage?! Is it still reliable at the lower supplyvoltage?

Another design I found on the Web, is on the attachment, what about it, are there any drawbacks, apart from not having a short circuit Protection?

Thank you very much!
 

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I cant see how this design can deliver 100 watts into 8 ohms with the voltage rails it specifies. Even if it could by using higher rails the output transistors specified would blow.

If you use my circuit with 50 volt rails you should;
- change R6 to 12K (this leaves enough voltage for T4)
- change R17 to 27K (less gain)
- change T1 & T2 to BC546 (these are more common and cheaper)
- use one less FET per rail.

You will have an amp module that delivers about 110 watts into 8 ohms and around 190 watts into 4 ohms depending on the quality of your power supply.

There is no short circuit protection offered by my design either (not yet anyway).

Cheers
 
Hello,

Quote:
I cant see how this design can deliver 100 watts into 8 ohms with the voltage rails it specifies. Even if it could by using higher rails the output transistors specified would blow.
---

Yes, thats what I thought of, the quality of the Output transistors isn't that good either, maybe its a nice projekt for lower supply voltages.
One pair of these Devices should not be enough to stand the current while giving the power.

_______

I decided using quasi's design.

I did already read the thread and I found the 1 device pair version of this amp, created by Keypunch. Is the Layout-desugn OK? (well for me it loocks correctly)

Regarding the point that I dont want to listen to pure sinus signal and that my transformer is only rated for 500VA (stereo amp) I beleive 1 Pair of the devices schould be Ok-any drawbacks?

Quote:

If you use my circuit with 50 volt rails you should;
- change R6 to 12K (this leaves enough voltage for T4)
- change R17 to 27K (less gain)
- change T1 & T2 to BC546 (these are more common and cheaper)
- use one less FET per rail.

You will have an amp module that delivers about 110 watts into 8 ohms and around 190 watts into 4 ohms depending on the quality of your power supply.

There is no short circuit protection offered by my design either (not yet anyway).
----

I also thought of using the BC546 device for the Input, they are much more easy availeble and I do have some of them, Itry to get a machted pair.

The given Power is not too critical, I just want to listen to musik-could be even less.(for my purposes)

I doesent matter, that there is no schort circuit protection, Iam not going to expect it to short while standing his (the amp) hole life in my livingroom.
 
Re: bias current?

BlacK_Chicken said:
Hello

What bias current should be applied on the Mosfet amp using 50V rails?

thank you very much!


Hi,
You should set the bias current between 30mA to 50mA per FET pair. So for a 4 FET board (2 pair) set the bias current between 60mA and 100mA.

You can set the bias for higher current, but I doubt you will hear much (any) difference.

Cheers
 
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