Dx Blame MKIII-Hx - Builder's thread

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Negative Andrew..... a lot of guys use to read your posts

I personally do not use to read because too many criticism and usually just a few little help..but, i have friends that read and when your post is positive, instructive, creative and helpfull they inform me and i do run to read.

They say:

- "The man is in good mood today... he forgot his bombs at home today"

But if friends does not "filter" the conversation to me..then i do not came because sometimes there are too many acid posts to my personnal taste.

Thank you...good and instructive post, teaching us things, helping people to undestand..this is great!, usefull!, positive!, helpfull and friendly.

regards,

Carlos
 
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What is your point?
That you do not read?
Or that you do not like to see any opinion, nor science, that does not agree with your version of science?

The basic problem is that the vast majority of Members here are too lazy to put in the effort to inform themselves.
These same lazy Members expect to be spoon fed.
 
Can anyone tell me whether this is 100pF 500V Cornell Dubilier silver mica?
I got them ordered through Ebay, wish like to know for sure.
I can't read pF with my multimeter.

Regards,
Rudy
 

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The bootstrap does what it's supposed to do.
It supplies a nearly constant current through the VAS as the output signal voltage varies.
It does this by swinging the supply voltage to the resistor junction (or in this case the resistor to CCS junction) to maintain a nearly constant voltage across the resistor/CCS. That voltage divided by the resistance/effective resistance is what the VAS wants to see.

The result of this is that the bootstrap creates a virtual voltage that can swing outside the supply rail voltage. That virtual voltage is what delays the onset of clipping.

The bootstrap has no effect on the VAS supply rail voltage. The VAS side does not benefit from the enhanced non-clipping characteristic.

Asymmetrical clipping of a bootstrapped VAS sink/source is not a sign of bad design. It is a natural result of the topology.
If you run your amplifier at levels such that it never clips then you won't notice the asymmetrical clipping.

As a footnote;
I don't know why I waste my time with these unhelpful posts, since few seem to read what is posted.

What about regulating the supply to the vas stage ...?
 
What is your point?
That you do not read?
Or that you do not like to see any opinion, nor science, that does not agree with your version of science?

The basic problem is that the vast majority of Members here are too lazy to put in the effort to inform themselves.
These same lazy Members expect to be spoon fed.

Lol, stick to the tech stuff Andy , you missed his point by miles .. :)
 
I personally don't let asymmetrical clipping bother me in the slightest.
For me the issue is rock solid stability and quality of sound, which can be subjective, but is at the discretion of the Designer.
If this is achieved then the amplifier is a success.

I don't mind either, I just want to understand all the subtelties of amp designs, this one in particular.

Carlos, it impressed me each time I understand something about your design :)

AndrewT: there's more readers than you think, and this thread being (obviously) searchable, your writings leaves valuable knowledge that can be retrieved by anyone.

I can't wait for my new drivers to arrive.
In theory, they will make "the dent" disapear. -VE sticking will need to be addressed by the clamp diode no matter what parts are replaced. (theory theory... will post empirical tests when I'm done ) :)
 
One day, a friend of mine that really appreciate good music came to my house. I showed him my project, the Hx amp. After about an hour of listening a reasonable volume, we cranked it up quite a bit. His comment was: Wow man! This thing make the music not louder but BIGGER... It just gets HUGE!

I think it describes it perfectly, it just gets HUGE! hahaha.. Hx if for HUGEx

I finally received my parts. And at the end, the Hx amp is simply great as is...

General warning: The images you're going to see are for your sole entertainment, it doesn't reflect the result you may have with your own Hx amp, I've modified it to entertain myself and to learn "how stuff works".

That being said, for the three pictures below, here are my modifications... Which one do you prefer? Why?

Filename = Measure2
VAS = 2SC1819
CCS = MJE15033
DrvN = MJE15030
DrvP = MJE15031
Cdom = 100pF
Baker = NO

Filename= Measure3
VAS = 2SC1819
CCS = 2SA1837
DrvN = 2SC5171
DrvP = 2SA1930
Cdom = 100pF
Baker = No

Filename = Measure4
VAS = 2SC1819
CCS = 2SA1837
DrvN = 2SC4793
DrvP = 2SA1837
Cdom = 100pF
Baker = NTE177 (BAV20 equivalent)

M.
 

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Hahahahahahah!

Here you have a huge ahahahahah!:)

Milk Sheik from Alibaba is happy....he became rich of enjoyment, as hundreds have built this amplifier.... this is a kind of pleasure, fulfillment and realization money cannot buy or pay for it, the pleasure to see people having fun, enjoying.... this comes for free..the same way we give something to others for free, as a gift.

You see, even a trouble into the waveshape while distorting... a post death manifestation obtained during authopsy, is driving people happy.... you see Cannonica feeling good, wayne having fun, Vostro having joy....BWW, Evette, Bonfis having good time... Cannon inviting people to evaluate, searching for perfection...offering solutions and options.... imagine the time people goes watching home walls having anything interesting to do...feeling their lives hard, fruitless, useless compared to what we are feeling now..me and these folks.

For sure we have a life!

This make me laugh..... Dx amplifier are so good that even after death (operating outside the usefull power spectrum as very few guys will listen while this machine clipping)... even this way people find a way to have fun.

A parallel, or some analogy, may be to drive an engine at rpm higher than the limit, then evaluate the noises it does when breaking parts because lack of lubrication.... well.... there are all kind of pleasures in this life...some guys have enjoyment watching speakers blowing...internet has thousands of speakers being fried.

This amplifier popularity is increasing a lot... first was a damage in the image...now a days people is ordering dozens in Brasil.

I would like people to search bugs in the after death waveform from the ultimate amplifier..the Dx Super A....i do not have scope anymore...mine is broken (while trying to fix the smps i have fried the analogic circuit too) and i am waiting DSO to produce a better model to buy (the one they made is not that good)... so...maybe, because i have not inspected (only in the simulator) while distorting, we may have something in the waveform...some interesting artifact too.

I would like to say that i am sorry, but the Dx Super A sound even better than this one.

I forgot to say when publishing that:

- "Dx Corporation reserve the right to make modification in order to ugrade the unit"



Ahahahahahahah!

Have you listened my laugh Andy?

regards,

Carlos
 

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Zimmer, from South of Brasil, have ordered some pcboards

to provide his close friends...but so many guys asked then he ordered a new batch.

If you want, then go to him, he is authorized to produce and distribute... i do not know how much it is, i also do not want to know, not interested in that stuff..it is between you and the "german Zimmer"...i have instructed to them to make it cheap...but this depends on how many pcboards he have ordered...if hundreds, then price goes down...if a dozen sets alike Juan did..then pcboard price increases.... also i have instructed Zimmer to make contact with Alex mm, because of his layout.

imap.eletro@gmail.com

I personally do not put my hands on money, i have my job in the State Government and this is what makes me distant from the dirty money stuff, that corrupts and shows all the worst things from humans.

No one, have ever, received any package with pcboards from my hands.... having my adress as sender.

From these guys that produces pcboards i have received samples, not money...no profit...all advantage i had was to build my amplifiers having a set of pcboards for free.... one set...not several sets.

regards,

Carlos
 
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For oscillation, you can try 22pF to 100pF, between bases of input pair,
This is common practice, I hope people don't disagree :)

See attached, ignore component numbers etc, its only to show where cap (C2) is.

Regards
 

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22pf in series with a resistance Vostro

This results much better.

But watch harmonics... the result with and without this capacitor..then decide.

I am all time long in the workbench doing things, trying things...so, all these things were tried, several times... and in many amplifiers...the reason why i know something about audio is have practice..i use to go listening and simulating to know what represents the modification i did... also i check into the simulator, to see what represents my ear's evaluation.

Audio is something human perceive... this has no connection with numbers..sometimes we have bad results in the simulator and nice results in listening tests.... we must evaluate listening..not watching screen or datasheed or calculation results...this serves for communication with others, because feelings, sensations, is almost impossible to communicate...reason why we use numbers...as a tool, not a dictator...just a tool.

I use always a reference... a non tweaked channel, same speaker, same audio source, same power, naturally flat and equal..because we have an enemie.

Our enemie is ourselves.... the hell thing is "i think so"...another enemie is "I believe that...."... there are other enemies connected to rules, uses and tradition.... i use to learn doing... making comparison with a non tweaked channel.

Many times i had belief.... i was sure the modification would be better....then i feel, i heard it better, i believe it was better...was a matter of faith..all that vanish when i compare with the non tweaked channel..i was wrong... several times wrong...much more than 50 percent of the tries i was wrong...i do think we have troubles to evaluate things...it is our SELF (psychological SELF)

In Brazil we have almost 150 million computers,,, each one of them have a voltage regulator before the computer power supply...have some filters, have a fuse, have an autotransformer with several taps, have relay and an integrated circuit that senses voltage variations and switches autotransformer taps.... this is plus 5 percent, plus 10 percent and plus 15 percent..also minus 5, 10 and 15.... but the SMPS we use to feed mother board has much more voltage regulation, much more capacity than the hell thing....but "belief"....."i think so" have made this with the population..now a days no one has courage to connect a computer direct to the mains.

Our mains is stable in voltage and frequency....we have not more than 8 percent plus and minus variations..and frequency variates 0.3 percent only.

Man.... i am sure i know 10 times more than the average forum guys..... because i know that " I do not know...i am sure i do not know... i do mistakes..i do evaluate wrong"...others do believe they have the knowledge..but they do not know this i have learned.

The real knowlege comes from the real world practice...hold the soldering iron and do the changes you believe..and then you gonna know a lot.

This" lifeless" capacitor will show you something we usually do not know.... test it..check it..but compare!.do not believe in your beliefs.... calculating it is great, simulating it is nice...go and check in the real world.

Picture shows 150 millions of faith and belief...people sometimes use those one that have wheels.... goes into the floor, nearby the mains outlet...in the back we have 6 AC female plugs... a sophisticated unusefull AC extension.

Stee does not give a "tip" to tradition, rules, uses and these things...he does his thing and do not care what people think about...he listened and he felt great...and this finished!.....go to him..there you have the real knowledge.

regards,

Carlos
 

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I don't think I'm gonna push my researches farther. I'm really satisfied with what I got. The VAS transistor is gonna be the 2SC1819, but for all the other ones, I'm gonna put back the originals, as designed by Dx.

I'm gonne leava the NTE177 as the baker clamp, for the "rev limiter" not to stick when lifting the throttle, hahahha...

My amp is on the bench since 2 weeks now and I miss it in my listening room.

I put the 2SC1819 for the VAS only because it will give better theorical results, having the lowest Cob of all the NPN I got with that pinout.

Yes, the initial design is THAT good :):):)

Martin.
 
Canon,
pics 2, measure3 and pic 3, measure4 are seriously wrong. There must not be oscillation on the waveform.

Canonica's results 3 and 4 are very reminiscent of what I had prior to adding the stopper resistor to the drivers i.e. parasitics on the positive peaks. I also notice the dent is now absent from the down going segment of the positive peak. Did that coincide with adding the new VAS? My dent was eliminated by disconnecting the boot strap.

Steve
 
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