Yet another amp - simple inverted with 10x gain, mosfet output stage - Page 9 - diyAudio
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Old 30th March 2012, 01:36 PM   #81
mikelm is offline mikelm  England
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I think +10 rather than x10 ?

unless you refer to OLG . . .
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Old 30th March 2012, 02:08 PM   #82
sonnya is offline sonnya  Denmark
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You are right about it. +10
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Old 30th March 2012, 04:14 PM   #83
sonnya is offline sonnya  Denmark
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Quote:
Originally Posted by padamiecki View Post
hm, you have hf switching hiss. it is -180db down @10MHz
in Kenpeter's proposition there is no HF hiss from >10KHz

but anyway I like you project very much
I am pleased that you like it.

Any Way, i would like to see other versions of it and builds. It is not complicated to build also.
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Old 8th April 2012, 05:44 PM   #84
mikelm is offline mikelm  England
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Hi Sonnya,

Your new design is very clever . . . not very high OLG but very low distortion.

My DC linked fetzilla version has higher OLG in the audio band which I'm enjoying very much just now but this upgraded version of yours is just too tempting to resist. It will be a good nice comparison of the different approaches.

I do enjoy high feedback amps if they're stable enough to also be smooth especially for classical music but I have the feeling your design is going to sound very good.

It may be a while before I will get around to it but I'll report here when I do

cheers

mike
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Old 8th April 2012, 08:11 PM   #85
sonnya is offline sonnya  Denmark
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It Will performers equali good with triple ef output but it Will need a Series coli of about 500nH - 1uH.

The idle power consumption is the double (~12Watt at +/- 35Vdc) for the triple EF
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Old 13th April 2012, 07:44 PM   #86
mikelm is offline mikelm  England
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I would not inclined to add anything that causes stability issues so please excuse my ignorance but what is the advantage of adding a triple ef output stage ?
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Old 13th April 2012, 09:34 PM   #87
sonnya is offline sonnya  Denmark
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Hi Mike.

The tested triple EF does not cause instability.

The only three reason to run it on a triple EF is:
  1. Less high order harmonics
  2. Easier to match than mosfets
  3. The Mosfet tested on my speakers and by Raidho on the C1 C2 and C3 gives a more soft bass section. We have not verified it but we think it is due to the fact that the rDS value raises with the increased Die temperature.
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Old 13th April 2012, 09:44 PM   #88
sonnya is offline sonnya  Denmark
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They do say that the first watt is the most important. Try sim it at 190mVpeak input.!

I have made small changes to this circuit and should be able to go under .04% at 100khz at 64watt in 8R
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Old 14th April 2012, 06:05 PM   #89
sonnya is offline sonnya  Denmark
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Quote:
Originally Posted by mikelm View Post
I would not inclined to add anything that causes stability issues so please excuse my ignorance but what is the advantage of adding a triple ef output stage ?
Hi Mike.

I am going to make a mosfet version of the AMP under All circumstances.

I Will let you know about the build.
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Old 14th April 2012, 06:42 PM   #90
mikelm is offline mikelm  England
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Hi sonnya,

Yeah, I didn't really mean stability issues - just that the speed and stability of an amp is pretty high on my list priorities so I am disinclined to take designs in the other direction.

While doing spice research on DC linked fetzilla I found increasing the o/p stage bias was the simplest way to decrease high order harmonics and this slightly helps with stability. I have yet to do a real world comparison of different bias levels.

The levels of low order HD in this design are already so low that it is no longer an issue for me.

I also intend to build this design but to enable a direct comparison to other front ends I will use my composite Mosfet / Lateral mostfet darlington pair o/p devices.

Did you ever see an amp with mosfet / bjt composite darlington o/p devices ? I always thought this would be a pretty cool combination - but I never saw anyone do that.

cheers

mike
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