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#1 |
diyAudio Member
Join Date: May 2007
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Inspired by keantokens headphone tests I just had to try out the Rush cascode/NTP on the JLH input.
In this application it isnīt that funny as it sims worse than the original?! More current through the Rush? |
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#2 |
diyAudio Member
Join Date: Nov 2007
Location: Dallas
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You might oughta Taylor around that Rush to keep both comparator emitters
current more or less at constant. That way voltage drop won't curve so much... Its never gonna be constant, or you wouldn't get any error voltage swing at the collector resistor. But you can approach that ideal. No, wait... Your JLH IS a Taylor! Holding R10 (and R2 on the right) at two emitter drops. I just didn't see at first. But then again, those are output emitters under dynamic conditions for a constant voltage reference...??? Perhaps this makes emitter drops in the Rush to copy a similar dance? Two emitter drops (in the Rush) may simply double the magnitude of this non-linearity. Which is really the non-linearity of the output emitters. Last edited by kenpeter; 25th January 2010 at 07:11 PM. |
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#3 |
diyAudio Member
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I thought there was perhaps a benefit from having the complimentary emitters back to back like that in terms of distortion cancellation ?
__________________
"The test of the machine is the satisfaction it gives you. There isn't any other test. If the machine produces tranquility it's right. If it disturbs you it's wrong until either the machine or your mind is changed." Robert M Pirsig. |
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#4 | |
diyAudio Member
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Quote:
Transistors only have 3 terminals, there's only so many ways of putting them together. Over the years we've enshrined all sorts of circuit pieces with names, usually after the person who published it somewhere, but there really aren't that many ways of doing this. The tunnels and passages that connect all the different topologies together are a lot of fun to explore and I think it's a big part of the hobby for some.
__________________
"The test of the machine is the satisfaction it gives you. There isn't any other test. If the machine produces tranquility it's right. If it disturbs you it's wrong until either the machine or your mind is changed." Robert M Pirsig. |
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#5 |
diyAudio Member
Join Date: Sep 2001
Location: Melbourne, Australia
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Gareth,
The RC is good, but so is the singleton...... bear with it, it's worth a good look too. I suspect you need to run your RC at around 1mA minimum, 1.3/8.2mA (160uA) is not enough. I don't believe you need R9 as you are not using the RC as a phase splitter, though the idea does have merit here. Hope this helps, Hugh |
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#6 |
diyAudio Member
Join Date: Dec 2004
Location: N/A
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Try adding 100ohm resistor between emitters of rush cascode, it will help in linearising the response and will provide you with much flater bandwidth and HF response.
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#7 |
diyAudio Member
Join Date: Feb 2003
Location: ..
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then you can "fold" the rush cascode input, changing one Q polarity and get the diff pair which has the even order distortion cancellation, input offset cancellation and high input Z on both inputs all in one
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#8 | ||
diyAudio Member
Join Date: May 2007
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Quote:
This one is just to find if there is some magic hidden in the Rush. Quote:
Adding 100ohm doubled it one more time. Will add the LTP version for comparision. Last edited by revintage; 26th January 2010 at 07:17 AM. |
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#9 |
diyAudio Member
Join Date: Nov 2007
Location: Dallas
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Not exactly... You got Rush + Taylor + JLH.
If Taylor was working with a good reference, it would be holding both emitters of the Rush at constant working current and voltage. Linearity would be moot. But your Taylor's voltage ref for comparison and correction of Rush collector current is the JLH drive, and one output transistor. Not exactly what you call a steady voltage reference, once the music starts... This voltage non-linearity is copied to Rush collector current by Taylor circuit. Then Rush modulates the problem twice over a single emitter. But not its own fault, I gotta blame abusing output and drive transistors as voltage reference. |
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#10 |
diyAudio Member
Join Date: May 2007
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Hey Ken,
You must show me the Taylor? This as the circuit is exactly a JLH 10W with the added Rush in the input/feedback stage. Note the 0.1ohm is just for monitoring Iq, should maybe be made smaller. To me a Taylor, simply put, is closely related to a WF with transistor instead of capacitor in the "feedback" from the top of the upper device(mut be a resistor on top of the drain/coollector to generate a signal) driving the gate/base of the lower. Last edited by revintage; 27th January 2010 at 08:25 AM. |
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