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Old 3rd May 2006, 12:37 PM   #1101
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Default John...

EVERYBODY who hears it, likes it! I have owned a lot of preamps over the years (with one exception, all tube types). The Blowtorch is the best of the lot, and not by a small margin either. Needless to say, it mates well with my JC1s
 
Old 3rd May 2006, 06:27 PM   #1102
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I have heard the Blowtorch in several systems including mine. Bob Crump visited and was kind enough to bring his personal preamp. I am sure John has made it clear that this product is the combined effort of three talented people. John does the design and board assembly. Carl Thompson did the design of the boards. He is a retired designer of state of the art video production equipment. Layout is so critical with that type equipment. And, the late Bob Crump was responsible for the voicing and final assembly of the preamp. Bob was one of those unique people who carefully evaluated every component for sonic character. Every switch, wire, connector, resistor, cap, etc. is specifically selected for their application. I mention all this to point out that the circuit design is just a part of this amazing product.
This thing throws the most holographic image I have experienced. The noise floor is nil and every performer is so clearly defined in that space. Let me give you a example of it's ability. I was sitting in the sweet spot while Bob sat at least 45 degrees off axis close to the left channel speaker. He asked me to switch places with him and check out the image. I did and to my total amazement, the image was stayed steady and everything was still in the same place in the soundscape. Simply amazing IMO. Now if I could just afford one
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Old 3rd May 2006, 06:45 PM   #1103
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Default ...still in th same place...

Space imaging is mainly made by attributes of speakers....
 
Old 3rd May 2006, 06:48 PM   #1104
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Default Re: Blowtorch in Europe

Quote:
Originally posted by Geophysicist
Well, that MAY change. I'd estimate roughly 50:50 odds that there will be one in London this year - mine.
I might take you up on that, and I'll show you some good pubs in return.
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Old 3rd May 2006, 06:50 PM   #1105
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Default Imaging

If the imaging works off axis as well as it does in the sweet spot, the speakers also are very special. My speakers are not so forgiving.
This artifact of playback indicates that the phase is fairly flat across the midband. Plus no frequency related delays.
This is an area where the lack of feedback is beneficial. Feeback usually screws with the phase response. This may be why some prefer no feedback for small accoutic music and feedback for large orchestra. The multi-miked recordings really are all over the place when it comes to preserving an event.


George
 
Old 3rd May 2006, 07:06 PM   #1106
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You have in it little bit mess, George... Good and fast amp have only several degrees of shift at the edge of accoustic band and on the middle is it only tenths of degree...
 
Old 3rd May 2006, 07:31 PM   #1107
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Default Re: Imaging

Quote:
Originally posted by Panelhead

This artifact of playback indicates that the phase is fairly flat across the midband. Plus no frequency related delays.
This is an area where the lack of feedback is beneficial. Feeback usually screws with the phase response.
This is a total nonsense, demonstrating how the "marketing science" washes brains of the poor DIYers.

Phase reponse is unambiguously related to amplitude response. Wide amplitude response means minimal phase shift in the midband. For the system with bandwidth 2Hz - 300kHz (which is quite normal) there will be no interesting phase shift in audio band.
 
Old 3rd May 2006, 07:53 PM   #1108
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The attached picture shows amplitude and phase responses of the power amp that I use. It is a feedback design, OLG = 80 dB, OLG frequency cutoff corner (-3dB) > 20kHz, closed loop gain = 32dB. I would be grateful if someone could show me significant phaseshifts in the audioband.
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Old 3rd May 2006, 08:01 PM   #1109
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Default Re: Imaging

Quote:
Originally posted by Panelhead
My speakers are not so forgiving.
George,

which ones are you using ?
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Old 3rd May 2006, 08:36 PM   #1110
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I would suspect that what you experienced was a combination of the dispersion characteristics of the speaker combined with the exceedingly low noise floor of the preamp (and amp?). The low noise certainly contributes to the illusion of image specificity. For what it's worth, I have noticed the same phenomenon with the Blowtorch, Parasound JC1s, and Sound Lab A-1s.
 

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