John Curl's Blowtorch preamplifier part II - Page 3082 - diyAudio
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Old 4th December 2012, 05:42 PM   #30811
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Thank you John. BL factor then.
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Old 4th December 2012, 06:06 PM   #30812
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This current vs voltage argument is pointless. Of course, it is BLI, so what?
Almost all loudspeaker systems are DESIGNED to operate properly with voltage drive.
This can go back to Rice and Kellogg who INVENTED the direct radiator speaker in about 1925. That is the only way that it can work optimally.
Individual drivers, of course can be current driven, just like servo motors usually are, but that is a special case.

Last edited by john curl; 4th December 2012 at 06:13 PM.
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Old 4th December 2012, 06:12 PM   #30813
Pano is offline Pano  United States
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An interesting distinction, John.
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Old 4th December 2012, 06:30 PM   #30814
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Quote:
Originally Posted by john curl View Post
This current vs voltage argument is pointless. Of course, it is BLI, so what?
Calling it pointless certainly doesn't make it so..
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Originally Posted by john curl View Post
Almost all loudspeaker systems are DESIGNED to operate properly with voltage drive.
You state the obvious.

Focus, John.

When a 10Khz sine is sent from an amp into a wire which has an impedance different from line, there will be a reflection. This can be easily viewed using a directional bridge, like the 8721A unit. This measurement does not require a line anywhere near a wavelength, a few meters is easy.

As a result, the load will not be responding to the amplifier voltage as it is sent down the line, but something else.

How the cable alters it, that is the question. Measurement of the current within the line will be more indicative of what the speaker is responding to.

The current vs time will be impacted by the line. My primary concern is transient response and it's impact on soundstage. I am not interested per se in the steady state response you speak of. I generally become bored very quickly when listening to pure sines.

jn

Sheesh, don't you know anything about Agilent 8721A directional bridges? I've known about it for something upwards of .....10 minutes now...get with the program..
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Old 4th December 2012, 06:38 PM   #30815
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Originally Posted by Kindhornman View Post
What determines when one of these opamps or even a discrete device is discontinued?
I'm interested by the response too, while i suspect the answer to be purely commercial.
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Old 4th December 2012, 06:39 PM   #30816
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Oh really? Well, make it good!
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Old 4th December 2012, 06:44 PM   #30817
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Originally Posted by jneutron View Post

When a 10Khz sine is sent from an amp into a wire which has an impedance different from line, there will be a reflection. This can be easily viewed using a directional bridge, like the 8721A unit. This measurement does not require a line anywhere near a wavelength, a few meters is easy.

As a result, the load will not be responding to the amplifier voltage as it is sent down the line, but something else.
So would the easy solution be the Mogami wire with 8 ohm impedance as shown in Nelson's article, perhaps terminated as also shown in article? Seems easier and more "attractive" than dressing 8 pairs of CAT5/6 cable, even though only subtle changes, sometimes, were heard between the various cables.
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Old 4th December 2012, 06:45 PM   #30818
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I'm actually facing to a choice, in order to mod an existing device composed of severall opamps. There are so many solution that my question is more philosophical than else and i had never made real test about various combinations.
On a sonic point of view, is-it better to use (when possible) the same OPA(with the same sonic character and, may-be some compromises ) or different ones (with different character but may-be, more adapted) when they are one after the others ?
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Last edited by Esperado; 4th December 2012 at 07:13 PM.
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Old 4th December 2012, 06:51 PM   #30819
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Oh really? Well, make it good!
Make what good?

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So would the easy solution be the Mogami wire with 8 ohm impedance as shown in Nelson's article, perhaps terminated as also shown in article? Seems easier and more "attractive" than dressing 8 pairs of CAT5/6 cable, even though only subtle changes, sometimes, were heard between the various cables.
I'd center the Z to minimize the difference in the delay. 20 ohms would seem ok to me. 4 pairs of #18 gets you down near #12awg. No need to go nuts.

jn
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Old 4th December 2012, 06:56 PM   #30820
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JN,
While using four pairs of #18 would you do anything fancy here? What I mean by that would you braid the wires a la Kimber cable and his interwoven stranding or just forget it and run everything in parallel?
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