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Old 23rd March 2012, 09:54 PM   #61
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If it is a myth than it is spread by much more than wiki....i am not talking about driving a tube to clipping...just the slight amount of 2nd harmonics introduced....
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Old 23rd March 2012, 10:35 PM   #62
popilin is offline popilin  Argentina
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Hi jmilledoc
I understand your point, we never talk about music here.
For these things in history, the musical notes in the Western system, are as 2 ^ n, in terms of its frequency, that is the reason why the second harmonic is pleasant, it falls into the previous/next octave with the same musical note.
Triode physics tells us that his main distortion is the second harmonic, even harmonics in general, otherwise the transistor distorts the odd harmonics, it falls into the previous/next octave with a different musical note, which is unpleasant.
Do the experiment with a piano or other keyboard and see, (hear)
Best regards
Johann
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Old 23rd March 2012, 11:12 PM   #63
tinitus is offline tinitus  Europe
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Quote:
Originally Posted by SY View Post
And not to be facetious but, yes, if you're designing a hifi amp (as opposed to a guitar amp), you actually would do better selling the 12AU7s and getting another tube which can be used in a simpler circuit and give higher performance. Your circuit does extract better performance than usual for that tube type, but the 12AU7 is not a very linear tube to start with.
SY, I suppose you suggest other than ecc types

according to this spec sheet. the ecc82/12AU7 have the lowest distortion of the commonly used ecc types, and seems pretty much independant of the voltage, as well as the gain

http://www.tubeampdoctor.com/images/...sion%201.0.pdf

doesnt that also imply its the more linear of them



edit, sorry, posted spec sheet on wrong tube, and now corrected
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Old 24th March 2012, 12:18 AM   #64
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Many years ago i built a pre-amp using a pair of 12au7 SRPP's as a differential pair with a sand CCS at the bottom (B+ around 450v). Besides the pain of matching (and keeping matched) the 12au7's, it was one of the most amazing sounding pre-amps i ever heard. I ended up running balanced lines out to the amplifiers which had a true balanced input.
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Old 24th March 2012, 12:44 AM   #65
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Quote:
Originally Posted by Merlinb View Post
+1.

I disagree with wavebourn. SS devices don't have sharp corners in their characteristics, except when you completely run out of headroom, which is out of bounds anyway.
The problem is, I have MS in Electronics Engineering, and learnt physics of semiconductor devices in details... It disagrees with your statement. No other bounds except potential barriers in semiconductors. And all laws are exponential.
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Last edited by Wavebourn; 24th March 2012 at 12:46 AM.
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Old 24th March 2012, 12:47 AM   #66
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Quote:
Originally Posted by popilin View Post
Hi Wavebourn
How lucky that I see you around here.
Could you give me another trick to remove the magnet wire enamel?
I'm going crazy with an OPT, and I can't with 0.2mm wire.
Aspirin does not work because the enamel is polyester imide resin.
And tested with acetone, thinner, and up brake fluid !!!
Fire tends to ruin the wire, please, help me.
Best regards
Johann
The truth is, you are more lucky: we have great chemical scientist here on the forum, his nickname is SY.
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Old 24th March 2012, 12:48 AM   #67
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Speaking of the personality types, should I say subtypes, we are all DIYers. I like playing with the technology, I like playing with the cheaper end of the spectrum of vintage vacuum. So far most of the solid state stuff in the toys that I construct tends to be in the power supply and voltage regulators, or maybe a constant current source in a Long Tail Pair.

This 12AU7 SRPP circuit was stated to be a Line / Preamplifier and an experiment. An experiment perks my interest. For a line amplifier 2V RMS output is a lot, more than is needed to drive a power amplifier into clipping. This 12AU7 has a mu of ~ 17. For a line amplifier a mu of 17 is better than 33 for a 6DJ8. Perhaps this circuit has a gain of 10 which is still a little high to follow one of SY’s low distortion hybrid SS / Vacuum “His Master’s Voice” vinyl machines or a CD output. In this 2012 type of application there is seriously little distortion added. Not bad fun either.

If this circuit is used at higher voltage and distortion output to drive a power output stage there may be some of that equal and opposite cancelation thing going on here. This could catch on and become popular. Who Knows? Think of the ugly little duck 6CB6 pentode Pete Millett uses in his Engineer’s Amplifier.
DT
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Old 24th March 2012, 12:50 AM   #68
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Quote:
Originally Posted by jmillerdoc View Post
If it is a myth than it is spread by much more than wiki....i am not talking about driving a tube to clipping...just the slight amount of 2nd harmonics introduced....
You may search for "Harmonizer" here on the forum, I posted schematic few years ago. It has a knob to dial, from zero to max. Try for yourslf, which level of 2'nd order armonic sounds better.
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Old 24th March 2012, 01:24 AM   #69
avp1 is offline avp1  United States
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Originally Posted by Wavebourn View Post
And all laws are exponential.
If you really have EE degree, you should know that it is mostly a case when you use bipolar transistors. FETs have very different laws, that is why they are used in designs by Nelson Pass and others. Moreover if several transistors are made on the same die, you can use circuits that change transfer function to something like hyperbolic sine, which is almost linear within relatively wide range of values. You can't use similar circuits with tube since there is no two tubes close enough for them to work.
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Old 24th March 2012, 01:37 AM   #70
popilin is offline popilin  Argentina
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Quote:
Originally Posted by Wavebourn View Post
The truth is, you are more lucky: we have great chemical scientist here on the forum, his nickname is SY.
Hi Wavebourn
Thanks for your feedback, I hope that SY can help me.
Best regards
Johann
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