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Destroyer x Amplifier DX HDII version.

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http://picasaweb.google.com/salesmonster/DXHRIIBuild/photo#5147275751666677938

It is best to take the point to the groundstar there by the bottom spade... don't use too thin wire, as the amp's power will runn trough it i case of some mallfuntctions and it can't protect your tweeters if burned off.

http://picasaweb.google.com/salesmonster/DXHRIIBuild/photo#5148397743153281554

Take this measurement with servo connected to PCB...

Well done with the pictures...

Some pointers for future constructions....

Start with smallest componenst first, wire links, small resistors, and work your way up, this makles it easier keeping the components in place while you solder upside down.
For zener diodes (and most other similiar packaged components), you get better dissipation (i.e. the power rateing goes up) if you allow a few millimeter air clearance under them...

It seems you are in the group that got only 4 small insulating pieces... one of those should be used for the bias servo to isolate it electricaly from the heatsink. Idealy you would have received 6 pieces, but clarity on actions normaly is higer on things done than those that are going to be done., use the other piese on the transistor by that resistor that is installed underneath the board.

Also if you want to try an output inductor in parallel with the 18R resistor on the board, you should bridge its holes and install the resistor and inductor offboard.. the inductor will be pretty large..

Thanks for keeping us updated

P.S. use 50V or preferably higher voltage caps please.
 
Main advantage for toroidal, is they tend to be small enough to fit in the case with the rest of the amp... and even if you want to house them seperately they tend not to stand so tall, so will fit in a cheaper lower profile housing.

Negatives; lets through a bit more noise from mains supply, larger toroids need some inrush limiting for power on surge.

EI transformer is roughly the inverse of the toroids... Large, My HRII PSU must clock in between 20 and 30kgs on its own at an estimate... You need your feet well planted before attemptimg to lift it. negligible inrush current, and lets through less garbage...
 
Nordic: Did you base your PSU off of the board assembly you are selling?

I was wondering about the 4700uF caps, or if I would see improvement with more capacitance. I know some of the biggest improvements I would get with commercial gear was beefier PSUs. The one that comes to mind would be Naim. They will sell you a really nice product for an arm and a leg...but if you want to unlock the real character of the equipment, that'll be another arm and leg. And for that price, what you got was the PSU they should've sold you to start with. I love the free market system.
 
The 4700uf caps are sufficient for 50W into 8ohms at least...

I have 1 pair 4700uf and 1 pair 10000uf caps in mine (I had some 10000ufs spare after getting the Panasonic's that fit on the amp PCBs).

Free market is a wonderfull thing, i was looking at using only 'boutique' resistors for some completed modules of the new Precision model... erm well $22 per channel...
 
I could realise, doing, that each ampere will need, at least 4700uf or filter

For instance....one Precision channel have 2 amperes consumption each channel, full power (166 watts over 8 ohms)....this means 2 amperes each rail...and into 8 ohms.

Into 4 ohms you will have 4 amperes each rail.... or something around that..... so.... 20000uf each rail to one channel only.

Having two channels into a single supply, value goes higher... near 40000uf each rail....but this is into 4 ohms.

So.... 20000uf each rail use to fit our needs into Precision.

How this works:

You inject 5 hertz and go with the oscilator volume up till you have unclipped maximum power into 5 Hertz....usually this is very near the maximum into the amplifier i use to make.... 5 Hertz is infrasound.... infrasonic frequencies are not audible...but if you have small condensers...you will listen the hummm into the moments the speaker is into the maximum forward excursion and backward excursion (movement...maximum amplitude)... this means we gonna listen the supply noises...the mains frequency will modulate, will be listened, will be together the maximum power peaks.... i could find that 4700uf each ampere can control that.

But when you increase the voltage... the need will be reducing.

Into 35 volts it is 4700uf...but into 63 i could see it is 3300uf or something around that.

Minimum, to Precision, into 8 ohms... really the minimum to feed two channels using a single supply is 14000uf each rail.... going to 28 or 30 thousand microfarads (uF....means 30 milifarads) each rail to 4 ohms operation.

Is my method precise?

No!...but works.... try and you will see.

regards,

Carlos
 
The HRII goes to 2 amperes each rail, maximum power, using 4 ohms loads

Having a single supply feeding two channels, and using 35 to 37 Volts as the supply voltage, you will need 20 thousand microfarads, or 20 milifarads (20.000uF) each rail as minimum!

Of course, increasing it you will have better supply.

This is when you are using a single supply feeding two channels..there are more economical sittuations, for instance, operating with 8 ohms only you will need 10000uf each channel.

When you have series inductor into the supply, you cannot add the condenser you have into each rails, say, inside the supply...because the inductor you will not have those folks added..so.... some overkill, while using inductors in series into the rails are a very good idea.

The reference i am giving you folks...because doing that for long time...and you can check my ideas doing the tests with 5 hertz into the input (big condenser will be used into the input while doing that, because normally 5 Hertz are into -3dB).

1 ampere, till 45 volts will need 5000 uf (4700uf)

1 ampere, from 45 to 63 volts will need 3300uf

1 ampere, from 63 to 100 volts will need 2200uf

Not precise..but works...try it by yourself..never trust me or other folks... the best sittuation for you is to check everything folks say to you...this way you will learn deeply the subject, will never forget and will "really know the whole thing"

Complementary information, about the Dx Standard supply into this adress:

http://www.diyaudio.com/forums/showthread.php?postid=1386655#post1386655

regards,

Carlos
 
Nice work Nordic...congratulatins once again.

Very impressive.... very good.

regards,

Carlos
 

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Electrolytic Caps

When choosing the electrolytic caps for this amp (and power supply), is the amp very sensitive to what type of caps are used?

I'm considering the Nichicon VR and VZ series. I have heard good things about the Panasonic caps as well. Is this even worth worrying about for this amp? Also, as I build up the power supply, I'm looking at the possibility in using it to feed the Dx Precision.

Dave
 
People said Panasonic is special.

In my point of view they are all the same.

My choice is how they look, how big they are and how much they cost.

But, i can be wrong.....so... go to Panasonic, a lot of people say they are excelent.... some folks said they sound good...i have put one into my ear and i could hear nothing..ahahahahahah.

They will say i am deaf and idiot...no problems, i use to say they are crazy!!!

regards,

Carlos
 
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Mounting power transistors

As a former tube amp builder I have a practical question for the experienced HRII builders. How are you gents/ladies mounting your power transistors to the heat sink?

I started drilling and tapping 4-40 screw thread into the sinks, but it takes a long time! Is there an easier technique I'm not aware of?

Thanks,
Francois
 
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