Dx Blame MKIII-Hx - Builder's thread

[destroyer X]

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

[AndrewT]

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.

[Vostro]

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.

[BMW850]

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

[evette]

Yes they are. Evette

[BMW850]

Thanks Evette, will soldering in the weekend the 2x 180pF out and these 2x 100pF in.

Regards,
Rudy

[a.wayne]

Originally Posted by AndrewT

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 ...?

[a.wayne]

Originally Posted by AndrewT

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 ..

[canonnica]

Originally Posted by Vostro

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 )

[canonnica]

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.