Dx Evolution, a new amplifier from the "Corporation" - diyAudio
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Old 28th March 2009, 05:55 PM   #1
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Default Dx Evolution, a new amplifier from the "Corporation"

Dx Corporation exists in my dreams only...but who knows what future will bring to us...or what I gonna make the make this future comes true.

I was waiting to listen before to open a new thread...but friends insisted that i should open a new one.

The amplifier is an evolution from the old and good Dx Amplifier, the Dx Standard....based into that amplifier i'm intending to obtain lower distortions in numbers together better audio reproduction into the real world.

It may use CCS to feed energy to the differential, also another CCS to feed current to the automatic bias control and more two CCS circuits, one to feed the NPN driver with 25 miliamperes of current and another to feed the PNP driver with 25 miliamperes of current.

The amplifier was simulated and it is now assembled, some informations you can read into the Dx Amplifier thread, were i have made an introduction about this amplifier showing several pictures and some ideas were explained there..... the amplifier resulted great into simulation, and soon i will be listening.

It uses a dinamic biasing system triggered by the audio signal level... the bias circuit has a standard VBE multiplier circuit that adjusts (a little bit only) current into the stand by mode...and this current may be around 750 miliamperes..... so, the amplifier is biased into some kind of advanced AB bias or class A if you prefer as it will be able to reproduce some watts into class A..... when you increase volume, or audio peaks enters the bias circuit, it will reduce the bias current to allow the amplifier to work into class AB giving you the power you need without the heat problem we have into low power reproduction....less than 80 watts will be spent from your supply to give you 50 watts RMS into 8 ohms with small distortion..... but the first watts will be into real class A operation giving you the advantages into the crossover distortion exactly into the power levels more often used...so... the circuit adjusts, reducing bias, in accordance with the audio level entering the driver transistors and bias control.

Circuit will be tweaked, reason why i am not publishing it, here, and today..but you can have an idea watching the Dx Amplifier thread when i tried to make an introduction and to inform the Dx Corporation friends.

As soon as i listen and tweak i will publish schematic, informing how it works into a detailed description, informing currents and voltages and all needed informations to allow you to assemble if you want to.

For a while it is under testing, not listened for a while..... in a couple of days i will return with more informations about.

Dx Amplifier thread has an introduction that will keep yourself rid of too much suffering with our natural audioholic curiosity.

regards,

Carlos
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Old 28th March 2009, 06:00 PM   #2
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Default Here you have a picture.


A prototype board, my style, was assembled and checked.... will be needed some time to adjust and to listen together family and friends.... in a couple of days this may happens.

The automatic bias is not my creation... existed since 1978 i think, as JVC has used something alike... also Technics..... the Brazilian Gradiente has used into the best amplifier ever made by this company (licensed)... i have just tweaked and adapted to my needs into simulator...i do not even know how it will perform into real life listening tests.

regards,

Carlos

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Old 28th March 2009, 10:18 PM   #3
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Default Here is the basic schematic that gonna be tweaked


attached,

regards,

Carlos
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File Type: gif dx evolution.gif (89.7 KB, 653 views)
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Old 28th March 2009, 11:06 PM   #4
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Hello Carlos

Very good this automatic bias, yes the first watts are very important, for sure I will read your listening tests.

Dx corporation have now a new born baby

Gaetan
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Old 29th March 2009, 12:32 AM   #5
taj is offline taj
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I'm waiting patiently for the Brazilian judge to announce his score. Is it gonna be a fine Burgundy, or more like something my dad made in the back yard out of weeds?

waiting... Shhh! The judge needs to concentrate.
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Old 29th March 2009, 07:18 AM   #6
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Default Thank you dear Gaetan and dear Taj...both of you are close friends


I have the amplifier almost "ready to go"..but i have to tell you the true.... i am afraid to power on without friends helping me to judge.... some guarantee to be fair into the judgement.

Because i felt class A mufled during almost all my life.... this means 48 years listening amplifiers (since 9 years old)... so...i have strong suspection this unit will be mufled into low volumes because will be operating into class A.

Also i have some Psychological alergical problem related class A.... one of main home enemies during our "global warming season".... my home temperature is 32 degrées celsius and reducing to 30 during the nigth.... fans are blowing air continuously to make my life less unconfortable (air conditioned spend too much energy, and this means a lot of US dollars when the electricity bill arrives).... imagine a class A heater playing here..... oh!... where is my gun?

This was made to reduce numbers into the simulator... to reduce distortions...but i really do not appreciate class A heaters, even recognizing them as top performers because keep us rid of crossover distortions.

I will travel today with my family, will be busy this Sunday.... then i will search for some courage during monday.... i am really scared because of possible deceptive moments.

I am preparing myself to produce a treble booster into this amplifier... i am almost sure it will be a little bit mufled.

You may be happy with class A dear Gaetan...as your place is very cold... those things can be even a good heater to your room.

48 watts of heat during stand by mode is really a terrible hot spot!.... well.... i use to make my amplifiers not only to me...they are made to forum folks assemble and enjoy...so.... what i think about class A is not so important as there are a lot of forum folks that loves class A amplifiers..so... this one will be for them.

I was thinking about class A yesterday..... the good solution to distortions, in special crossover distortions....well.... connecting the idea to the global warming problem (bigger than you imagine) it looks alike to burn folks skin as a solution to avoid them to perceive the weather as too much hot... they will be suffering because their skin burned that will not even perceive the global warming as their problem will be much bigger than the weather problem...they will not even feel the heat as the skin burned will bother them more.... this solution seems to me so interesting alike class A as a solution to distortions.

Yeah!... toast them because they will stop to complain about global warming!

hehehehehe.

regards,

Carlos
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Old 29th March 2009, 09:30 AM   #7
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Default Re: Thank you dear Gaetan and dear Taj...both of you are close friends

Quote:
Originally posted by destroyer X

You may be happy with class A dear Gaetan...as your place is very cold... those things can be even a good heater to your room.

....

Yeah!... toast them because they will stop to complain about global warming!

hehehehehe.

regards,

Carlos

Hello Carlos

A good heater to my room... ha ha ha ... that's a good joke.

I don't use class A, it use to much energy, but it reduce crossover distortions, and using class A for the first watts only are much more ecological.

Bye

Gaetan
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Old 29th March 2009, 02:03 PM   #8
jaycee is offline jaycee  United Kingdom
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Interesting looking output stage, with current sources on each driver. I'll be interested to see how this one comes out

I have the chassis from an old Teac amp begging to be used... not sure about it's transformer though, it will give +/- 75VDC... the original amplifier circuit certainly wasnt designed for this! and I am sure the transformer (a large EI type) is only good for about 200VA.

I'm trying to convince it to take a 2x35V 500VA toroid I have, but even if I move things about inside, I don't think it will fit :x

www.darkmatter.myby.co.uk/teac/top.JPG
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Old 29th March 2009, 03:36 PM   #9
norazmi is offline norazmi  Malaysia
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Hi Dx,

Class A amp? Duhh... big heatsink ..... its not suiteable for my country also...
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Old 29th March 2009, 04:30 PM   #10
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Default Hot...too much hot to my taste...but may be fine to Scandinavian folks.


May be good to polish ice blocks into the Ice Hotel from Sweden (made using ice blocks i think)...melting the ice or snow surface will produce nice shine when watter turns ice back again.

Also to cook some eggs.

But it uses to produce a nice mufled sound (hehehe)

I am back from my trip.... Federal Road... travelling at 150 Km/h as Police do not like to work Sunday morning...ahahahahah!

But too much hot to test amplifiers this evening..will wait better weather late at nigth or early morning... the main test uses 1 watt of power only..full power tests can be made latter when people is waken up.

regards,

Carlos
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