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Stefanoo

Stefanoo

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Joined 2006
Acting on the input current acts on the gain.
With 6 BFs 3.3ohm degeneration and 60mA LTP I get 63dB.
63mA per side is a huge amount of current. hmmm!!!

anyhow increase of input current and sqeezing everything to the max, it looks like there is not so much gain avaialbe anyway.
 
Stefanoo

Stefanoo

Member
Joined 2006
Joachim Gerhard said:
For high Gm you need a lot of current that flows in the Fets. A bipolar has 10x higher Gm for the same current so with bipolars you have a much better relationship of idle to Gm.
That is unavoidable.
Click to expand...

true consideration.

Then can this be re-arranged for BJT?
It is a thought I am considering now since the many disadvantages I am encountering with FET, i.e. : of low gm, problem driving a lo Z source, avaialability.

What is your thought on this?
 
Joachim Gerhard

Joachim Gerhard

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Joined 2009
suesskindaudio.de
This has to be rearranged to balanced but it shows the principle.
 

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Stefanoo

Stefanoo

Member
Joined 2006
Joachim Gerhard said:
This has to be rearranged to balanced but it shows the principle.
Click to expand...

Is it a scan of the linear audio issue you have recommend? I didn't have time to order it I will do it today and get over with.

I would like to know your opinion if for this balance desing you think we should persue the scheme in rev 7 and try the InterFet device or re-arrange for a differential BJT kind of technology.
 
Stefanoo

Stefanoo

Member
Joined 2006
Joachim Gerhard said:
I am eager to see the Interfet at work, bipolar works anyway. That is always an option and i did it in the Paradise.
See an even better bipolar low noise circuit. Forget the post before.
Click to expand...

that is an interesting circuit.
If you are eager to see the Interfet at work then let's continue with that path.
The only thing is that I am concerned with gain.
With 750mS dual package there shouldn't in theory be any issue with reaching out the needed gain, it's just that on simulation it looks like a huge amount of current is required.
 
Stefanoo

Stefanoo

Member
Joined 2006
Bad News on the IF3602.
I called the company and there is a lead time for these of about 12weeks now.
They are really nice and it is possible to buy small order with just a minimum of $450 which isn't bad at all and he mentioned that they can do less parts on Credit Card if needed.

So it is possible to have these parts but the time is just very, very long!

If there is anybody that knows how to obtained them from a distributor or something please let me know!
 
Stefanoo

Stefanoo

Member
Joined 2006
Joachim Gerhard said:
I am eager to see the Interfet at work, bipolar works anyway. That is always an option and i did it in the Paradise.
See an even better bipolar low noise circuit. Forget the post before.
Click to expand...

Joachim I am trying to get this application circuit working on spice but it appears not to work.
I am attaching the picture of the simulation, I am sure I am missing some stupid connection or something.
 

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