Dx Precision, finally released... now debugged and better than HRII

[Nordic]

I have tested 470uf and 1000uf on the output transistors of the PI, and could not realy perceive a diffirence...

If you want to use a bigger value... get it in axial form, then it is easy to apply it under the board...

 

[destroyer X]

Nordic.... i will be very happy to receive, from you,

the list of forum folks that have ordered Precision 1 boards.

Also the ones that have not received, because of some "bureaucratic" problems...payment and that stuff.

I have asked you into the forum, also have sent you an E mail...seems you are very busy, but please, make some effort to keep me updated, related informations, about that stuff.

regards,

Carlos

 

[Nordic]

Hi Carlos, mail sent....

No problems I think the guys are just getting anxious because the design to producition cycle took so long.

I think everything is under control now and I am jsut waiting to hear from the first guys to recieve their stuff... there was also a bit of an enquiry fever with the original HRII stuff as the first guys got their stuff...

Cheers
Nico

Got a bundle of washing in the machine and a sick wife in bed today... then I have to prepare something for lunch... what a morning.

 

[billabong]

Re.rail caps:

I have no desire to use larger caps. My interest is in seeing what effect smaller rail caps would have on the sound.

The only reason I increased the Black Gate caps from 47 and 10uf to 100 and 47uf was that they would fit, and yet be of small capacitance compared to the 470 and 220uf specified.

Although I have no personal experience of it, my feeling is that there may be little to be gained in using larger rail capacitors when using P/S capacitors such as the Mundorfs that I will be using.

I will have to discover this for myself.

Regards,

billabong.

 

[Nordic]

These caps are not a bad idea to have very good quality ones... as this is the decoupling caps... as the current (which always flows in a complete loop) delivered to outputs flows through this ...which means the music also goes through them...

They also function to negate inductance in the cable between the main reservoir caps and the amp.

 

[billabong]

Good point Nordic.

I've almost convinced myself to try the Black Gates first. I'll still order the larger Nichicon UHE caps -just in case.

billabong.

 

[destroyer X]

Protective resistances, how to measure stand by current

To adjust stand by bias current.

regards,

Carlos

 

[destroyer X]

Precision I power using 64 volts to the main supply and 62 volts to the voltage stage

Attached a simulation result... this one to four ohms.

regards,

Carlos

 

[destroyer X]

Here you have over 8 ohms loads

I would be happy to inform the unit was tested during 3 hours long, over 2 ohms resistances as load, full unclipped power into the output, sinus signal producing more power than the informed power and the amplifier show reliability and safety during operation... heat was controled, temperature was stable and not high... around 50 degrées centigrades to my 31 degrees celsius environment.

It is a huge, stable, excelent sonics amplifier that will turn you happy...for sure.... guaranteed!!!

regards,

Carlos

 

[destroyer X]

During tests, made September 2007, the supply had losses and voltage dropped

to 58 volts.... the load was resistive only, 2 ohms.

regards,

Carlos

 

[destroyer X]

If your supply is huge, you gonna have a very big power

Observe into 2 ohms, if your supply can keep the 64 volts stable...or if it is 70 volts without load and dropping to 64 during high consumption periods of time...you may have this power continuous and much more during peaks...and if you accept some clipping distortion you gonna have more than 1 Kilowatt into a stereo Precision unit that will eat a lot of good brands you have into the market.

More transistors will be needed to continuous operation under such condition.

regards,

Carlos

 

[Chrisr3521]

hi after a little poking around lokking for parts i stumbled over these transistors Toshiba 2SA1302 and 2SC3281 which replaced the 2SA1943 and 2SC5200 could i use these instead without changing anything else?

thanks
chris

 

[destroyer X]

Yes...you can use them and not need of changes.

And i think with advantages...those ones, if not fakes, are very good.

regards,

Carlos

 

[Greg Erskine]

hi after a little poking around lokking for parts i stumbled over these transistors Toshiba 2SA1302 and 2SC3281 which replaced the 2SA1943 and 2SC5200 could i use these instead without changing anything else?

thanks
chris

Hi Chris,

The 2SA1943 and 2SC5200 are the newer replacements. The Toshiba 2SA1302 and 2SC3281 have been out of production for years.

There is a chance the Toshiba 2SA1302 and 2SC3281 are fakes, be careful.

regards

 

[Nordic]

Red, use Toshiba's website to find an authorised distributor in your area....

Very slow progress this side... been sick all week, and now its turning into bronchitis.

Attached, some more unusual technique... the black is from the pen I used to draw the pads with before etching... this is the main circuit board for my valve stage... I told you it is simpler than transistors...

All I need to do is wire up the pots and groundstar to one side, and the valves to the other...

I am more of a believer in good components... something that stays the same capacitance as my schematic calls for, rather than swinging in value with increased voltage/frequency.... so do you... I have seen you use micas...

Also on the market you find similar components for diffirent intended uses.... someting that will stand powered on for hours or something that is just used quickly.. like appliances..

Also based on usage and design, caps can vary between a few hundred hours to a few thousand before they start the final drift towards decay... I like the idea of once something is build with components that will stand the trial of time better, it will be a long time before that case ever needs opening again.

Lastly I have pretty good ear, and have personaly experienced/ and often do pick up clear as daylight changes made by small things like bypass caps etc...

Some people can look at your face, go home and draw a perfect picture of you... some people can hear things and keep a near perfect copy in their heads.. some people can run a 100ms in 9 seconds, other will never achieve this with any amount of practice, I am convinced of this.

 

[space2000]

dear DX,

hi,

good morning. i have read throu this forum and learned that you have new version of precsion, it is Precsion-II. please can i have a circuit diagram with parts list? i don't know which is ur latest update circuit design.

thank you
michael

 

[destroyer X]

Precision II was not released.... people is already building the Precision I

The Precision I boards where shipped last week or something alike and they are already travelling...some of forum folks that have ordered have already received... and others have not received yet.

Now is time to wait them receive and build.... we gonna be here to help them...people will make mistakes and we gonna be here to give them support.... in the future..when the dust comes down.... then we will think to release the Precision II.

Sorry, will not be published those next monthes... this is something to think about, it will not be released before July.... i am thinking to make big modifications into the project already made.

regards,

Carlos

 

[space2000]

thank you DX

thank you DX,

ok, i am waiting for your sweet sound amp pr-II. today i will perchase a big sink for pr-I, and will do some recircuiting. hope everythings will be fine. this time still have to do in vro board, no chice but in dfrent way cause i will not so sure to making pcb board.

acutally i want to perchase the pcb board but problem is have to use credit card, which i don't use out of the country. i only can make payment in advance throu bank or remitence.

best regards
michael

 

[destroyer X]

I see.... you need an International credit card

When ready to order boards search for Nordic.

regards

Carlos

 

[taj]

some people can run a 100ms in 9 seconds

That sounds like my speed. (ms = milliseconds right?)

..Todd