Advice needed..

[dxvideo]

Hi all,

I am a DIY audio fanatic. And made many gainclones, MOSFET AB amps, preamps etc..
I know Tripaths chips for a long time. But have never tried one of them yet.
I already have a Class AAB lateral MOSFET (2SK1058+2SJ162) 2x100W amplifier for living room. But I heard really good thinks about 41Hz kits.
I have a pair of Wharfedale Diamond 9.6 for music and as you know they need really strong power amps to drive. With my MOSFET amp I am happy but I must try one of 41Hz kits.
At the moment I need your advices, which 41Hz kit is suitable for me? AMP1 or AMP2?
Thanks in advance for your replies.
PS: I have a 40+40v 500VA rated toroidal transformer and I want to use it.

[xenob]

I would recommend AMP2. It fits best to your transformer, it is for experienced builders and you can expect very good sonic results.
Downside is, you need to build your own power supply(but therefore you can tweak it more).

[dxvideo]

In fact I think I already have a power supply for it. Its a non-regulated one, have eight ultra fast rectifier diodes (BYW80-200), 4 x 4,700uF + 1 x 150nF plus series 0E68 resistors on each rail. Do you think will I need regulation or should I design another PSU for it?
Whats the general approximation for PSU? Regulated, unregulated or switch mode power supplies uses generally?
Thanx

[dxvideo]

And a final question,
What kind of heatsink should I use for it? I am not an average use and listen loudy music everytime. I have a 20x10x4cm huge heatsink, it has 18 fins and I guess its about 0,5-0,6 °C/W.
Do you think it will enought for AMP2?

[xenob]

Hi

4x4,700µF is not much, but it may be sufficient.
Jan writes:"A rule of thumb is to have a minimum of 1000uf capacitors per Ampere for each side (+/-) of the supply while 2500uF is better".
find more on PS here: http://www.41hz.com/main.aspx?pageID=99

Don´t forget you will also need a really well stabilized, ultra silent, regulated 5V for the chip supply

"Heat sink. For a 2x300W amplifier you need a heat sink rated at about 2 C/W or larger"

[dxvideo]

OK. Does 7805 + 5.6v zener enough for it?

[dxvideo]

I know, I asked a lot. But;
As I mentioned, I have a 40 + 40v AC transformer and its rated 500VA. So I plan to drive 6 ohm speakers (Wharfedale 9.6) After rectifying I have 56V DC without load, but when I connect it my MOSFET amplifier the voltage reduces about 51V.
So should I consider the voltage as 51V or 56V? And for 6ohm driving my transformer will enough or not?
PS: I said I am a loudy listener, but I am not crazy, so I guess I will never exceed 70-80W per channel. I want this kit to have some "headroom"..

[xenob]

Hi,

according to (40Vx1,41)-1, you should have about 55-56V rail voltage.
500VA will be ok for 6 ohm speakers. With 4 ohm or less, current will exceed rating of chip, but also of your torroid.
Remember, e.g. with +/-45V rail voltage you´ll get 2x300W into 4 ohms.

An LM317 will be better than an 7805. To remove even more ripple you should design a two step, LM317 based, voltage regulator (like amp4 has).

[dxvideo]

I see.
But as my knowledge, maximum input voltage of LM317 is 35v. In this case I must use another transformer for it. Or I can divide the voltage by two power resistors and apply it to the LM317s input. I think that way because I plan to use two enclosures one for amp one for transformer. What do you say?
And with my power supply, maximum output level for 6 ohm is around 200W.. Is it? This is a true horror for my neightboors (and also my wife)!

[Mr T]

Hi,

I strongly advise you to build the best 5.00 volt supply you can afford. A separate small transformer costs nothing, associated with two cascaded LM317s and a bunch of decoupling caps, this is what you want, don't forget the crucial role played by the TC2001 in the AMP2 (and in other 2 chips derivative designs).

Oh yes, and 200W is only 3dB more compared to 100W.


Mr T