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John Curl's Blowtorch preamplifier part II
John Curl's Blowtorch preamplifier part II
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Old 29th October 2012, 12:34 AM   #28591
Esperado is offline Esperado  France
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Originally Posted by RNMarsh View Post
What if we used a signal which only had a zero to + (or -), repeated for awhile. Like a pulse. There is an average level that is + or an equivalent dc level. What does this do to the circuit...
Well...if it is a symmetrical amp, DC coupled, we can believe one side of the power stage will heat more and the other refresh ?
Offset can increase, or decrease...depending how it was ? or the level ? Or the one after the other ?
Distortion can increase slightly, or decrease, depending how the parts mismatch ?
Of course, the thermal inertia is slow enough for any servo can correct this DC (because your signal is a symmetrical signal with a DC equal to half its peak to peak value) before it become important, while the power units are thermally coupled with the radiator ?

But the main question i ask to myself is: What kind of instrument would produce such a signal ? Even Kick drums, with its first attack always in the same sens is globally near symmetrical, main dis-symmetry on half a period...
I noticed that kick drums can sound a little different, switching their phase, but i believe it is due to loudspeakers, as i never noticed impact on other instruments.playing in the same time.
Did i miss something ?
 
Old 29th October 2012, 12:52 AM   #28592
Esperado is offline Esperado  France
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Originally Posted by gpapag View Post
May be we should ban emoticons. They make things look too obvious
And destroy all those years, training ourself to never smile at our own jokes.
Animated emoticons are nice, Christmas night.
 
Old 29th October 2012, 01:55 AM   #28593
RNMarsh is offline RNMarsh  United States
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John Curl's Blowtorch preamplifier part II
R
Quote:
Originally Posted by Esperado View Post
Well...if it is a symmetrical amp, DC coupled, we can believe one side of the power stage will heat more and the other refresh ?
Offset can increase, or decrease...depending how it was ? or the level ? Or the one after the other ?
Distortion can increase slightly, or decrease, depending how the parts mismatch ?
Too broad... maybe this, maybe that. (many SE and other audiophile circuits are not symmetrical). Looking for numbers... after-all I am looking at .001 and less thd numbers for SOTA circuits. Looking for CMRR of at least -100 db.
It may not take very much asymmetry in waveforms to cause increase in distortion.... for some circuit topologies. Assume 1k-10K source Z for worst case. Also, for worse case, assume C/L gain is on the low side. Thx - RNM

Last edited by RNMarsh; 29th October 2012 at 02:07 AM.
 
Old 29th October 2012, 02:06 AM   #28594
RNMarsh is offline RNMarsh  United States
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John Curl's Blowtorch preamplifier part II
Fiber-Optic microphones: If you shine a light on a vibrating diaphram and pick up the reflected light via a f.o. to a detector.... you pretty much dont have to worry about noise, amps and Z and cable pick up of hum emi/rfi et al. Why arent more using them and developing them further for more recording appl? Why, why, why? -RNM

Last edited by RNMarsh; 29th October 2012 at 02:12 AM.
 
Old 29th October 2012, 02:11 AM   #28595
bcarso is offline bcarso  United States
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Originally Posted by RNMarsh View Post
Fiber-Optic microphones: If you shine a light on a vibrating diaphram and pick up the reflected light via a f.o. to a detector.... you pretty much dont have to worry about noise, amps and Z and cable pick up of hum emi/rfi et al. Why arent more using them and developing them further for more recording appl? -RNM
Far from it.
 
Old 29th October 2012, 02:18 AM   #28596
RNMarsh is offline RNMarsh  United States
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John Curl's Blowtorch preamplifier part II
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Far from it.
If you say so.
 
Old 29th October 2012, 02:28 AM   #28597
bcarso is offline bcarso  United States
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Originally Posted by RNMarsh View Post
If you say so.
Not asking for you to take my word for it. But without details, falling back on photonics as if it were some sort of panacea is naive. And when one adds the realistic details, it becomes much more pessimistic, most of the time.
 
Old 29th October 2012, 02:40 AM   #28598
RNMarsh is offline RNMarsh  United States
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John Curl's Blowtorch preamplifier part II
I will believe you only if you have tried to make such f.o.microphone. Otherwise, speculation means nil.
 
Old 29th October 2012, 02:42 AM   #28599
bcarso is offline bcarso  United States
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Originally Posted by RNMarsh View Post
I will believe you only if you have tried to make such f.o.microphone. Otherwise, speculation means nil.
The burden of proof or plausibility is with you. Please pass the port milord.
 
Old 29th October 2012, 02:51 AM   #28600
RNMarsh is offline RNMarsh  United States
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John Curl's Blowtorch preamplifier part II
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Originally Posted by bcarso View Post
The burden of proof or plausibility is with you. Please pass the port milord.
In other words you dont know what you are talking about. Ever used one? Go buy one and use it, then tell me about how naive it is. -RNM
 

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