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John Curl's Blowtorch preamplifier part II
John Curl's Blowtorch preamplifier part II
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Old 1st January 2011, 06:21 PM   #8361
scott wurcer is offline scott wurcer  United States
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Quote:
Originally Posted by Soundminded View Post
"AM and FM sidebands can be somewhat separated by phase."

And can they be separated by ear to? Would you know if you are hearing sidebands due to FM or AM modulation distortion by listening to it?
Just saying today's instrumentation could complete PK's study.

BTW, I actually liked some of the single driver setups at Burning Amp. All those horrible direct radiators are still going strong.
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Old 1st January 2011, 06:30 PM   #8362
Soundminded is offline Soundminded  United States
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Quote:
Originally Posted by SY View Post
Do a little bit of searching, it's not very difficult.

For anyone curious, that pitch ratio (440/441) is about 4cents. Here's a nice check on whether or not you can REALLY hear that: Audible Difference in Pitch Blind Test
I took the test and got two right out of ten. I didn't think I could hear it.

OK Wahib, you try it and tell us what you get.
 
Old 1st January 2011, 06:34 PM   #8363
scott wurcer is offline scott wurcer  United States
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Quote:
Originally Posted by wahab View Post
Out of curiosity, i just made a test now with a signal generator.
It s clearly audible, and i don t think i have an ear as good as
first rate musicians..
That you do not hear it doesnt mean that others can t as well.
Careful that's more like relative pitch. Wait ten minutes and turn the oscillator to 440 without looking then measure it. Try again later.
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Old 1st January 2011, 06:43 PM   #8364
wahab is offline wahab  Algeria
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Quote:
Originally Posted by Soundminded View Post
I took the test and got two right out of ten. I didn't think I could hear it.

OK Wahib, you try it and tell us what you get.
Well, i got 9 out of 10, but i used the speakers at very low
volume; otherwise, i m sure it would have been 10/10....

I m sorry, but you ll have to add more precision in your
future project calculations...
 
Old 1st January 2011, 06:44 PM   #8365
wahab is offline wahab  Algeria
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Quote:
Originally Posted by scott wurcer View Post
Careful that's more like relative pitch. Wait ten minutes and turn the oscillator to 440 without looking then measure it. Try again later.
Right , Scott.
Indeed, the test in SY s link is easier due to the frequency sweep..
 
Old 1st January 2011, 06:54 PM   #8366
Soundminded is offline Soundminded  United States
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I retried the 5 cent test and got 7 out of 10. I got 9 out of 10 on the 10 cent test. One problem is that for some of them, one channel drops out during the test.
 
Old 1st January 2011, 07:01 PM   #8367
wahab is offline wahab  Algeria
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Quote:
Originally Posted by Soundminded View Post
I retried the 5 cent test and got 7 out of 10. I got 9 out of 10 on the 10 cent test. One problem is that for some of them, one channel drops out during the test.
Great !!
You are proving to yourself that you did ,intellectualy,understimate yours ears
all these past years.
 
Old 1st January 2011, 07:15 PM   #8368
simon7000 is offline simon7000  United States
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Originally Posted by anatech View Post
Now, unless that amp is at idle, varying load conditions should remove enough energy so that conditions would be too variable to simulate. It might be easier to build something like this up and watch it. Just a (total) guess.

-Chris
Chris,

Sorry I missed this, but a nice guess, however the L really is in Henries the C can get close to 1 F (okay .1) so with a pair of 8 ohm speakers playing average level of -20 re full power R would be closer to 40 ohms, so the load does come a little into play, but I see how that is not what it would seem at first look.

I suspect most of your measurement experience is at a well designed and built test bench. So you probably do not have as many motors interacting with your AC line. Which makes it reasonable with all your experience you haven't seen the problem.

Most of my systems are bigger than my shop so I have to do field measurements. They have HVAC systems that can cool an entire city block! Most also can coat the floor with ice.

So you might keep an eye out for it and let me know if it does show up in consumer gear.

BTY my shop is not that large it is only one half of an acre!

ES

Last edited by simon7000; 1st January 2011 at 07:44 PM.
 
Old 1st January 2011, 07:21 PM   #8369
Steve Eddy is offline Steve Eddy  United States
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Quote:
Originally Posted by Soundminded View Post
I took the test and got two right out of ten. I didn't think I could hear it.
If I'm not mistaken, getting two right out of ten is as statistically significant as getting eight right out of ten.

se
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Old 1st January 2011, 07:34 PM   #8370
simon7000 is offline simon7000  United States
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Quote:
Originally Posted by scott wurcer View Post
Careful that's more like relative pitch. Wait ten minutes and turn the oscillator to 440 without looking then measure it. Try again later.
Scott,

That is a test for "Perfect Pitch" and yes there are cases where some folks have demonstrated the ability.

Of course you really could use a function generator, most of the audio band ones can do FM. It is often called "Sweep."

I have done some work vaguely related to this area and will be doing more. I did a brief article for Sound & Video Contractor 20 or more years ago on a useful application related to some of this. Someone else then got a "Protection" patent on the method and never brought it to market.

So I will not be able to add any useful data to this topic.

ES
 

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