Suggest me an amp design!

[raypalmer]

Here's the deal. I'm very keen to switch into the wonderful world of active crossovers. But I have only a Cambridge audio Integrated amp, and a pair of LM3886 Gainclone Mono Blocks. So I'm not exactly where I need to be.

Here's what I want. I'd like to harvest the Traffo's from the Gainclone Monos and use them to construct two stereo poweramps. Said poweramps would be run with the Cambridge Operating as Preamp (it has pre-outs).

Desired minimums:

-15 watts per channel
-Stable to 4 Ohms (lower would be dandy)

Undesirables:
-IC Amps
-Class D
-Class A
-Excessively Complex Designs
-PCBs

Desirables:
-MOSFET, JFET Output
-Relatively simple topology
-Easily acquired parts
-Class AB
-Regulated, silent PS circuit


The transformers in question are:

(2x) 160VA Toroid with two 24V Secondaries.

[Tekko]

Destroyer X's DX blame ST.

[raypalmer]

Ehh doesn't sing to me. Good suggestion though.

Anyone else??? I'm dying here. Even any links to collections of schematics?

[nigelwright7557]

How about a classic AB amp ?
LPT with CCS and CM.
VAS with Vbe multiplier and CCS into a MOSFET output stage.
You can scale the output mosfets to suit the power you require.

[Tajzmaj]

Hi
Don't me understand wrong but if design is too simple it will suffer from distortion and/or oscillations........so you probably can't avoid pcb-s........the good point is that you have voltage low enough that it will be easy to care all unwanted things. What about to clone something good and reliable.......but it won't be so simple.....maybe Quad306.....

[kevinkr]

You might want to take a look at Nelson Pass's stuff a couple of threads over, and despite being class A these designs offer a lot of what you are looking for..

Take a look at the F5, it even sounds good..

[Tekko]

How about the mosfet citation 12 ?

mosfetcitation12 :: mosfetcitation12d.png picture by TheElectroNoob - Photobucket

I built this and it works just fine, gives around 50-80 watts into a 4 ohm load.

The original: mosfetcitation12 :: mosfetcitation12.png picture by TheElectroNoob - Photobucket

You can use almost any mosfet that have enough voltage and current capabilities.

[Mooly]

Quite a long thread but read it all...
My MOSFET amplifier designed for music.

Originally Posted by raypalmer

Desired minimums:

-15 watts per channel....................................Yes
-Stable to 4 Ohms (lower would be dandy).......Yes with proviso... I use with B&W 703 (3 ohm minima) but would advise dual die FET's be fitted for sustained 4 ohm capability

Undesirables:......................................Meets all criteria
-IC Amps
-Class D
-Class A
-Excessively Complex Designs
-PCBs

Desirables:
-MOSFET, JFET Output.........................Yes, Lateral FET Output
-Relatively simple topology..................Yes
-Easily acquired parts..........................Yes
-Class AB...........................................Yes
-Regulated, silent PS circuit..................That's up to you


The transformers in question are:

(2x) 160VA Toroid with two 24V Secondaries.

[Ian Finch]

Assuming these stereo amplifiers are external so heat is not a problem, the addition of full regulation with Mosfets is going to be a bit wasteful on power.
As Mooly points out, less than a double (expensive and hot) pair is not going to cut it with low impedance loads. I would think that BJT TO247 types would suit this task better.

Rod Elliott's P3A would be a good place to start, keeping headroom requirements minimal. It is simple, inexpensive and has a good track record as an active X-over amplifier. Wahab also has a nice triple BJT design he uses at low power in actives. My own breadboard of this was particularly good sounding with just 12W/ 4 ohm before clipping.

[raypalmer]

Originally Posted by Tajzmaj

Hi
........so you probably can't avoid pcb-s........

I can... populating a PCB is far less rewarding than laying it out oneself on perfboard.

Originally Posted by kevinkr

You might want to take a look at Nelson Pass's stuff a couple of threads over, and despite being class A these designs offer a lot of what you are looking for..

Take a look at the F5, it even sounds good..

Yes but I believe 500VA traffo's are needed for the F5, not mere 160's.

Originally Posted by Tekko

How about the mosfet citation 12 ?[/url]

Very interesting. Will one 160VA traffo per amp be okay though?