Dx Blame ST - Builder's thread - post pictures, reviews and comments here please.

[400kg]

Originally Posted by vargasmongo3435

I'm getting ready for ST I made like a map to see how it look if I have an error please be free to correct me I don't mind at all. plus this really confuse me sometimes but here is a PDF file of my map for ST. I also later I'm going to order not now but the power supply boards, here is the picture of my first board inspire from Miguel Nabuco.

Regards
vargasmongo3435

hi
Would you share the printable copper surface?

[destroyer X]

be tested...so.... you cannot give him 100% guarantee that it has no mistakes.

The only way we can be sure the pcboard has no mistakes is building it to be sure.

Because was based into a previously tested pcboard layout (Nabuco one) then it is possible that it is correct..but we cannot be sure if a mistake was made there when changing things to improve the layout.

He may want a positive or negative image related the copper tracks only..one in Black to hot iron transference method and other in white to photo chemical etching process.

regards,

Carlos

[vargasmongo3435]

Yes! mister Carlos is right, I did this layout for my personal use but if someone what it to try I can not said it has no errors because I copied for myself for later, as Carlos said it has to be tested with the iron etching technique and I want it to try maybe later and I still really busy putting together the Dx Blame Supercharged I'm not done yet with it, but... if you want it to try is on your own risk I can place the files here and you try out but with not guaranties is my personal layout still , the original work is on this website if you want it to go. check it out bro I just want it to add something, my name is not on the board because I did not created this board in the pass few months by reading a lot from the forums I have learned that is some one create a layout and all you guys that work so hard to put together a layout of any kind of circuit you got to give credit to the designer it take days even months to come out with the right layout that works I just learn that, I personally copied but is for me to learn but place my name on the board it was a mistake a made a couple of time I be honest with you guys a really big example mister Alex MM and Nabuco are my inspirations now is Herman too, but yeah people if you copy a layout please do no place your name on the board like I did it was my mistake and I learn that now, give credit to the original creator he or she deserved is a way of art respect those guys! I said that from my heart guys.

Greg's Web Site Greg's Web Site has all the info you need for etching your board, bias adjustment all that good stuff.


Regards
vargasmongo3435

[destroyer X]

Dx amplifier thread.

There's a video there.... another video latter today.

regards,

Carlos

[destroyer X]

and i have achieved awesome results.

Digital camera audio recording is not really fair compared to the real thing..but shows something about the quality...of course, the real thing is much better....naturally.

Dx Blame ST+ SuperA+Low pass+Blend+cheap speaker - YouTube

regards,

Carlos

[destroyer X]

The Military band of Music for celebration and the "keys from the town"..but i was invited, in a very respectfull and educated way, to subscribe to their forum...then i am there, gladly.

So different if i compare with the HT forum where they banished me three times, where i have to ask please to enter to explain things about my amplifiers that someone have published there...so different!..this brazilian forum is a business..they sell things there..so, a real DIY man is not a good idea as people prefer to build my things, then to buy their stuff.

I am uploading to youtube the "all about the Dx Super A"..showing it is a Dx Blame ST modified and tuned and showing each different modified part and supressed parts and differences in adjustments..also that we can use external Super A pcboard avoiding guys to prepare a new pcboard layout.

And Juan is making the new pcboard layout for us too.

It eated the Dx Blame ST circuit in the breakfast, despite it is almost the same amplifier, just tuned and modified in some parts..anything different...this time i have tuned by ears..last time was using simulator..and this is not that good....Dx Blame ST sounded lifeless compared to the Dx Super A - MKII (my Super A circuit, not Gradiente anymore and Dx Blame tweaked and tuned to optimize performance while listening)

Soon i will post the video link here, in portuguese and english..all bad english and bad portuguese but i hope gonna be helpful to you all.

regards,

Carlos

[destroyer X]

From the Dx Blame ST to the Dx Super A

I am already uploading another video showing your simulator things.

Dx Super A - all about - tudo sobre essa unidade - YouTube

regards,

Carlos

[maxlorenz]

Congratulations, Carlinhos!

BUT, just when I found the time to build the first channel of the Blame ST you come with a better amp!

Two days ago I finished one channel of the amp, with test PS, and it worked OK. Sound appeared to me as more refined than the DX HRII and I got superb bass (I used a secret weapon, though ). Unfortunatelly, on second power-on, yesterday, I made honour to your nickname and R22 and R18 fried...I supose bias was to high in the morning. Anyway, now I will investigate what happened and replace the broken parts to start again. Do I target 0.52V at the base of output transistors? I was working with 0.55V...

The sound reminded me one afternoon at a friend's place listening to SET + old Altec speakers.

[destroyer X]

This means your voltage is increasing slowly due to big condensers in the supply...also check the value of the rail resistor, the one that is burned nearby the VAS, right. side of the pcboard.

Have you increase the values of rail resistors?...if you did it, then reduce them.... some amplifiers did that...they also oscilated when you switch the power off and then they produce a noise when the voltage was dropping..there's a point, or a voltage, that creates some unstability.... the voltage grows up fast when we power on and voltage decreases when we power off... in these two moments this may happens for a milisecond or less..but if your supply increases voltage slowly or decreases slowly, then the critical point happens for too much long time and starts an oscilation because the whole amplifier is not correctly biased under this circunstances...it is going to stabilize..so, it is a non stabilized stabilizing sittuation..on the run..on the go.

This amplifier is not too much distant from the oscilation threshold..this is a dangerous trick to increase treble... producing and interesting effect...some guys call this defect, depending their mood or their intention.

You may have some transistor shorted..... circuit have oscilated.

Increase miller capacitor, install the 1K resistor in series with the BC546 colector (first VAS) install 33 ohms in the first second VAS emitter (BD139) and check if you have too much capacitance in your supply.

You was not lucky...seems you have a very high gain transistors.

Try to increase the gain resistor too.. i do not remember the value..but it is in the second transistor from the differential base to ground through an electrolitic condenser.

Do not replace these parts without test transistors first.. differential, and VAS stages.

If your condensers are not that big.... if you have not the noise after you power off (2 seconds after) then you got the terrible prize to be facing a very strange trouble.

regards,

Carlos

[maxlorenz]

Yes, Doctor DX, that were the symptoms: the speaker made "brrrrr" then smoke got in my eyes. Q10(BD140) is shorted.

Strange, I used (as always) a Variac to set the bias (with resistor instead of speaker) and no fumes appeared, even if V increased very slowly...

My rail resistors and base stoppers are 33R and the caps in board are 470uF (though the main are Rubycon ZL 100V), while the PS is only 12mF per rail.
So no regulated supplies for this amp, right?

It would be lovelly to see the schematics for the mods for a Super A

Thanks for your help!
Ah! I forgot to thank Metal and Rudi! Thank you guys!
(though the holes for the fuse-holder were too small, haha)

M.