Mine Dx Class A is based on JLH amplifiers
A little bit tuned, but result was not better while listening....measuring we can
have some advantage on my own....but just that.
If you wanna a suggestion, go to JLH.
regards,
Carlos
A little bit tuned, but result was not better while listening....measuring we can
have some advantage on my own....but just that.
If you wanna a suggestion, go to JLH.
regards,
Carlos
There is no official source.
Most PCBs have been created by Members.
Some unscruplulous fakers started producing PCBs commercially and as a result DX stopped giving away his designs.
Most PCBs have been created by Members.
Some unscruplulous fakers started producing PCBs commercially and as a result DX stopped giving away his designs.
It really disappointing that Dx has stopped publishing designs....He has made great contributions.....going to miss all of them....
I give up related to produce designs ...... and publish them
Matter of fact that i could not stop to be thinking about circuits...there are so many good ideas around, and i feel the need to try some ideas.
But our forum is an open door to obtain schematics and ideas, to have free support, to copy and to produce non authorized stuff to sell....we just cannot avoid.....our forum is a magnificent display, filled till the top with skilled people, united to make the best possible amplifiers...so...pirates comes here, like bees catching flowers to produce honey.
Not only the traditional people that use to copy stuff has landed here producing my amplifiers, selling in ebay, sometimes chinese sites,... well....they refering to my brand name, my name as designer .... and they say people can have follow up and my attention while they assemble or join units inside an enclosure, with my assistance...my help....... 😕
I felt offended with that stuff and decide not to publish anymore...it is enough what i have already made.
Worst than that, my own people started to do the same....and people that have learned stuff from me decided to produce their versions (copies) and to sell saying the circuit belong to them....this was even worse.....a knife in my back....but i have continued to produce in Brazil and new guys copying...then i have decided to make new designs and to offer assembled, no schematic provided.
Now producing small ammounts.....very small ammounts.... to Brazil only... Emitter follower output (traditional).... differencial with mirror and CCS.... 4 transistor VAS circuit, dual VAS circuit....and Super Feed Forward technique by Sansui.... this is the last produced....i may work alone...will produce pcboards at home, will assemble at home and will ship from my home..no schematic provided and life time Guarantee based in to some rules.
In our forum we cannot earn money......in threads like this one i cannot put advertisement for selling purposes...i have to go to a place no one goes, and i have to pay to put advertisement in places people do not see (hehehehe, i use add block, so i think people cannot see, because i cannot see)...if i do different, for free, group buys...then people come and copy.
I do not want to do this anymore...reason why i am keeping myself distant...well, i gave my contribution, it is time to other guys to take my place...some of them have already take my place.
regards,
Carlos
Matter of fact that i could not stop to be thinking about circuits...there are so many good ideas around, and i feel the need to try some ideas.
But our forum is an open door to obtain schematics and ideas, to have free support, to copy and to produce non authorized stuff to sell....we just cannot avoid.....our forum is a magnificent display, filled till the top with skilled people, united to make the best possible amplifiers...so...pirates comes here, like bees catching flowers to produce honey.
Not only the traditional people that use to copy stuff has landed here producing my amplifiers, selling in ebay, sometimes chinese sites,... well....they refering to my brand name, my name as designer .... and they say people can have follow up and my attention while they assemble or join units inside an enclosure, with my assistance...my help....... 😕
I felt offended with that stuff and decide not to publish anymore...it is enough what i have already made.
Worst than that, my own people started to do the same....and people that have learned stuff from me decided to produce their versions (copies) and to sell saying the circuit belong to them....this was even worse.....a knife in my back....but i have continued to produce in Brazil and new guys copying...then i have decided to make new designs and to offer assembled, no schematic provided.
Now producing small ammounts.....very small ammounts.... to Brazil only... Emitter follower output (traditional).... differencial with mirror and CCS.... 4 transistor VAS circuit, dual VAS circuit....and Super Feed Forward technique by Sansui.... this is the last produced....i may work alone...will produce pcboards at home, will assemble at home and will ship from my home..no schematic provided and life time Guarantee based in to some rules.
In our forum we cannot earn money......in threads like this one i cannot put advertisement for selling purposes...i have to go to a place no one goes, and i have to pay to put advertisement in places people do not see (hehehehe, i use add block, so i think people cannot see, because i cannot see)...if i do different, for free, group buys...then people come and copy.
I do not want to do this anymore...reason why i am keeping myself distant...well, i gave my contribution, it is time to other guys to take my place...some of them have already take my place.
regards,
Carlos
Attachments
Sir,
I can understand from your words that you have been hurt deeply by the actions of a group of people who misused your great designs for making money...Our world is like that, what can we do sir...?
I have learned a lot from your posts in this forum....I should have joined earlier...I have successfully assembled Dx, Dx nalme ST, Dx super A, Dx MKIII HX. Will send you the photos....
I like your philosophy and the way of looking at things....more over the sound that comes from your designs...
My heartfelt and sincere gratitude to you sir...
I can understand from your words that you have been hurt deeply by the actions of a group of people who misused your great designs for making money...Our world is like that, what can we do sir...?
I have learned a lot from your posts in this forum....I should have joined earlier...I have successfully assembled Dx, Dx nalme ST, Dx super A, Dx MKIII HX. Will send you the photos....
I like your philosophy and the way of looking at things....more over the sound that comes from your designs...
My heartfelt and sincere gratitude to you sir...
Dear Carlinhos,
Remember "imitation is a form of adulation"...in this case "copying"...and you are in very good company in that club: yesterday I found complete First Watt's J2 clone on eBay 😱
Your contributions to the forum and to "the Art" are inestimable, and personally I thank you for helping me getting rid of my fear for burning transistors, he, he.
Now I have built more than 10 working amps 😎 but still far from your more than 5000...
I offered my DX HRII to my godson and he couldn't be happier: first song he listened to was "Stairway to Heaven" and he almost got his pants wet, he, he.
My Blame ST has now an inexpensive SMPS from connex, slightly modded, and guess what, it still sounds like heaven. The Blame "edits" the music in a way, but in completely musical manner that it is a joy to listen to. 😎
I hope you will post musical examples on Youtube from your new "excess" amp!
Very best wishes, dear uncle,
M.
Remember "imitation is a form of adulation"...in this case "copying"...and you are in very good company in that club: yesterday I found complete First Watt's J2 clone on eBay 😱
Your contributions to the forum and to "the Art" are inestimable, and personally I thank you for helping me getting rid of my fear for burning transistors, he, he.
Now I have built more than 10 working amps 😎 but still far from your more than 5000...
I offered my DX HRII to my godson and he couldn't be happier: first song he listened to was "Stairway to Heaven" and he almost got his pants wet, he, he.
My Blame ST has now an inexpensive SMPS from connex, slightly modded, and guess what, it still sounds like heaven. The Blame "edits" the music in a way, but in completely musical manner that it is a joy to listen to. 😎
I hope you will post musical examples on Youtube from your new "excess" amp!
Very best wishes, dear uncle,
M.
But you could start group buys for your great designs , so people who are interested will stop looking to buy from other vendors, and those unscrupulous vendors will loose their business .
What do you think mr Carlos ?
What do you think mr Carlos ?
When setting bias current using 10ohm safety resistors - does the recommended circa 850mV to 1100mV reading correspond to the 33v power rail value only? If a +/-20v supply is used will the correct bias current be less and hence lower voltage on 10R resistors?
Don't set the output bias using a big resistor in the supply lead.
The bias CURRENT changes when the supply voltage changes, even when the bias voltage almost appears to stay the same.
Removing the test resistor effectively increases the supply voltage at the amplifier and the bias current increases.
You must measure the bias voltage across the output emitter resistors.
If your amplifier does not have any emitter resistors, then fit one to each output device.
The bias CURRENT changes when the supply voltage changes, even when the bias voltage almost appears to stay the same.
Removing the test resistor effectively increases the supply voltage at the amplifier and the bias current increases.
You must measure the bias voltage across the output emitter resistors.
If your amplifier does not have any emitter resistors, then fit one to each output device.
I have 0.33R and 5w resistors. Is that sufficient? Also there are no holes or traces in the PCB for the resistors. What's the easiest way to install emitter resistors with point to point? Also, what is the bias current I want then 100mA?
I had to test out my theory that the bias current as measured across 10R external resistors changes with supply voltage. All I had was a 53v dual rail. So I hooked it up and the bias current easily went up and I was able to get more and set it for 1000mV. Then tested the amp with music and it sounded fine an ran for 5 minutes until "pop" blew the fuses on my Abletec SMPS. Checking what caused the supply to blow it's fuses revealed the main 5200 NPN transistor shows 0 ohms across two of the pins. Caps are all still good. I wonder if this is the only part that got fried?
What is the max voltage for the Dx anyway? Will need to order some spare Toshibas power transistors.
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Based on instructions on Greg's website for setting bias. Adjust to get between 850mV and 1100mV across 10R. That's about 100mA right? Seems high as I was only getting 10mA with the 20v supply and it actually worked and sound good. But I have no idea what bias current across transitors is as this was the external "safety" resistor as advised by the official Dx amp setup instructions.
And did you try to check the actual bias voltage across the emitter resistors (Vre) AFTER you removed the 10r test resistor from the supply rail?
What si the Vre when mains voltage is at absolute max? Does it stabilise or does the current keep on rising?
What is your supply voltage? I just placed an order for 10pairs of the 5200/1943's for $11.
There are a bunch of amp and regulated PS plans that use this transistor.
The optimal Vre for a ClassAB EF output stage is discussed at length by D.Self.
For a 0r22 emitter resistor D.Self suggests 23.1mVre (= 46.2mVq)
For a 0r22 emitter resistor D.Self suggests 23.1mVre (= 46.2mVq)
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No one can manufacture, distribute and retail output devices @ ~ $11/10pr
They must be fakes !
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