L'Amp: A simple SIT Amp

[Zen Mod]

naah - I just mentioned how Pa is finding that side of science most amusing ..... and how seeing that was amusing for me ( mention him in this very context is my attempt to poke him to write something here in your great thread )

we are not talking about Nelson specifically , but about those who spotted same thing about process which leads to crystallization of some idea or solution

so - pleasure isn't always in discovering completely new things ( I have few more thoughts now about that but I feel constrained with my ZMengrish) , but can be found also in some newish way of combining some items/things/ideas already discovered .......

so - I'm not disputing anything , just catching normal tempo , after removing huge amount of snow from garage to street

 

[Michael Rothacher]

I understand.

I just didn't want anyone to misinterpret my mini-essay on originality.

I remember the first time I picked out the big dipper in the night sky. Many before me had done the same, but I enjoyed the discovery nonetheless.

 

[Zen Mod]

there is great reading in one of my favefave books , regarding that subject

An Inquiry into Values - Zen and the Art of Motorcycle Maintenance - diyaudio.rs

 

[Michael Rothacher]

You'll make a philosopher of me yet.

BTW, I finished the Hainish Cycle.

 

[Zen Mod]

yeah

The Word for World is Fun & Love

 

[juanitox]

for those who are building Sit AMp V1 fig 11 , if they exist i prefer now 0,1F of source bypass cap ; better than the 50000uf wich is a little short for deep bass region

 

[NYCOne]

Aleph Current Source

I've seen folks mention the idea, but has anyone actually tried the Aleph CS in a SIT amp?

 

[Nelson Pass]

Yes, works fine. I've been spending more time with mu followers for no
particular reason.

 

[NYCOne]

Aleph vs. traditional CCS in SITs

I was curious if you'd seen any differences in terms of distortion (assuming you've tried both). I have a set of R100s I'd like to try to add to my SITs in lieu of the IXTH6N50D2.

 

[juanitox]

another beginner question, on the Sit amp part one we can see that michael has draw a 8ohm load line to find the sweet spot . but later it is sais that the 2SK82 see the 8ohm speaker in parralel with the drain resistor ( 14ohm)

so why not to use a 5 ohm load line to find the Q point ?

 

[Michael Rothacher]

From the article:

And, the load may be something other than eight ohms; it might be the impedance of a transformer primary, the impedance of light bulbs in parallel with your speaker, or something else altogether.

 

[Zen Mod]

think static vs. dynamic conditions

 

[juanitox]

sorry guys i don't understand the output impedance inpedance ( static) of the Vfet will be 5ohm and 8ohm for charge ( dynamic) ???

 

[Michael Rothacher]

It (the example load line from the article) is an arbitrary example.

You're welcome to draw the 5 Ohm load line.

Also, as mentioned in the article, loudspeakers aren't usually pure resistors, they are reactive and their load lines are actually elliptical having an impedance which changes with frequency. Have a look at the impedance plot of your loudspeakers, for example.

Having said that, we often deal with lumped abstractions in the world of electronics in order to simplify the work (unless you happen to like working directly with Maxwell's equations). In this particular case we lump the model of a loudspeaker into a resistor.

 

[juanitox]

you see , talk to me like to a child and now i have understand,that my speaker is 8ohm nominal but not on the entire range like a resistor so the load line is just a "guide" not a strict law to find the sweetspot

thanks amigos

 

[Michael Rothacher]

talk to me like to a child

well, in the spirit of learning of course.

 

[Nelson Pass]

I was curious if you'd seen any differences in terms of distortion (assuming you've tried both). I have a set of R100s I'd like to try to add to my SITs in lieu of the IXTH6N50D2.

For the current sources, they work better with the mu follower than the
Aleph because the Vgs of the R100 is lower. I don't find much difference
between R100's and IRFP240's as mu followers, and so I go with the more
common part.

 

[NYCOne]

For the current sources, they work better with the mu follower than the
Aleph because the Vgs of the R100 is lower. I don't find much difference
between R100's and IRFP240's as mu followers, and so I go with the more
common part.

Again - Gracias

 

[juanitox]

question " du jour" i put a 0,022uF teflon cap between the primary of the transformer as main filter . the sound become very clean but the highs seems a little bit soft . do you think 0.022uf is too much ? any rules for that kind of filter ?

 

[Zen Mod]

For the current sources, they work better with the mu follower than the
Aleph because the Vgs of the R100 is lower. I don't find much difference
between R100's and IRFP240's as mu followers, and so I go with the more
common part.

Generg

are you digging what Papa sez ?

you can spare that R100 in Mu and use IRFP instead ....