Yes, several of my friends have invested in it. Also a bunch of guys on a Norvegian forum have bougth it and give it top$$ reviews
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I just modified one of my latest designs for i/v conversion for a mc cart input...I'm not an expert in mc carts...i just put a 0.1mv voltage source and a 10 ohm series resistor to sim the cart and an approximate 10x gain...I just used an available fet opamp in the library but that opa1692 might fit the bill.You get the fet bjt input and the transistor bjt input...You can do a lot of things with this arrangement I'm still studying it .Some of the components might be skipped , capacitors made smaller in value or removed.
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These circuits seem to put DC current through the cart, not recommended. The first one also has both the gate and drain of the FET at ground potential?
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It might put some dc in at startup , that is true...I only tried the bjt version on DAC output (there's a long topic about it ) , today i'm going to try the fet version (2sk117) on a pcm1701, but i think you can figure out a solution for that dc at startup.It's virtual ground after all.220uf/6v might be small enough with some manufacturers.
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OK, so in the first circuit all three terminals of the FET are at ground potential, how does it do anything? It will act like small resistor but I don't think that is what you want.
try it for yourself...
It's true indeed that biasing the gate is improving the distortion figure by 10db, but i really am curious if the spice prediction is right cause i tried with three different fet trz and it works with all of them in simulation.Today i'm going to find the truth with my Denon DCD 1560 as Guinea pig .If it's not working , just use the positive rail and a second resistor...
It's true indeed that biasing the gate is improving the distortion figure by 10db, but i really am curious if the spice prediction is right cause i tried with three different fet trz and it works with all of them in simulation.Today i'm going to find the truth with my Denon DCD 1560 as Guinea pig .If it's not working , just use the positive rail and a second resistor...
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https://www.diyaudio.com/forums/digital-source/336480-stage-town-4.html#post5770859
God damn! It's working really great without positive bias!
The noise level is ...next to NONE! That fet i/v section is getting me about 5v RMS from 1ma...
I'm absolutely positive about it used with an mc cart, but i'd probably go with the bjt version for mc cart because of the noise reasons.
The FET has 0 volts on all three terminals it indeed does nothing but act as a low value resistor, you get exactly the same result simply shorting it out. You clearly have little or no understanding of how these devices work.
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If you would have looked at my schematics in my other topic you'd see that i tried both, fixed bias and autobias , you can see the 5 v separate power supply on the schematic.I didn't wanted to use it mainly for i didn't wanted to deal with power supply induced noise.I lost 10 db thd out of 130db...so it doesn't really matter.
Funny thing is that i'm listening right now the circuit outputing 5v RMS with no audible noise at all and i really feel i.m listening to the best player i've ever come to listen too.
And i'm using opa2132 and not ad797 on pcm1701 because the 8k2 feedback resistor of the i/v stage and 1ma output dac doesn't recommend ad797. I still have 2 copies of your creation though and i'd probably use it with a more modern dac.
Please don't blame me for the fact that i designed something that nobody believe it works which is both elegant and performant!
Funny thing is that i'm listening right now the circuit outputing 5v RMS with no audible noise at all and i really feel i.m listening to the best player i've ever come to listen too.
And i'm using opa2132 and not ad797 on pcm1701 because the 8k2 feedback resistor of the i/v stage and 1ma output dac doesn't recommend ad797. I still have 2 copies of your creation though and i'd probably use it with a more modern dac.
Please don't blame me for the fact that i designed something that nobody believe it works which is both elegant and performant!
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It doesn't work, the FET does nothing and the op-amp does all the work and you can't figure out the difference.
Of course Scott has done this before.
Silly me.....
https://www.diyaudio.com/forums/att...ning-universal-diff-diff-head-amp-phantom-png
https://www.diyaudio.com/forums/ana...iversal-diff-diff-head-amp-3.html#post5672654
(Post #139)
Patrick
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