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Old 30th August 2006, 01:39 AM   #101
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Default They probably think we're nuts...

10" x 10"? That's a big chunk of hardware, flg!

Phone wire isn't so bad... at any rate, my horn doesn't hum or hiss with the JBL amp.

Just for kicks, I reconnected my ZV7-T to the center channel (yes, I run it balanced) and listened carefully to the center channel only. I think the amp is very revealing, so much so that it picks up any hash in the recording. Most of what I listen to are iTunes downloads. When I switch to a standard CD the hash (what little there is) disappears. At idle, I can stick my ear in the horn and can't pick up any hum, hiss, or distortion. My sweety must be part bat. (but only the good parts -- try to figure that one out, ha).

This amp is very strong with a JBL 2446 driver/horn combination. My ears are smarting from the spanking the JBL just gave them -- albeit a spanking with a silk hanky. Even up loud, the warmth and sparkle hangs in there. Silky, warm, smooth, class A.

Later, my friend,

John
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Old 31st August 2006, 02:39 PM   #102
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Default The daughter's golden ears...

I asked Ellen's daughter to listen to my arrangement -- her ears are so good she can hear the phone ringing downstairs and recognise who's leaving a message; I can't even hear the phone ringing. Anyway, she says she doesn't hear anything out of the ordinary, distortion wise, when she listens to one of her CDs on my system. Maybe I'm right, the noise Ellen heard was inherently embedded in my iTunes CD.

John
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Old 31st August 2006, 03:47 PM   #103
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Default Re: The daughter's golden ears...

Quote:
Originally posted by carpenter


I asked Ellen's daughter to listen to my arrangement -- her ears are so good she can hear the phone ringing downstairs and recognise who's leaving a message; I can't even hear the phone ringing. Anyway, she says she doesn't hear anything out of the ordinary, distortion wise, when she listens to one of her CDs on my system. Maybe I'm right, the noise Ellen heard was inherently embedded in my iTunes CD.

John

umm . . . there is nothing . . . there is no noise . . .
but . . . you have something . . . there is nothing else . . .
how much she likes that something . . . ?
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Old 1st September 2006, 12:30 AM   #104
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Babowana -- I think you are smarter than your nickname gives credit --

The girls are so use to hearing my pro-audio/class A audio gear that they aren't surprised by my acomplishments anymore. Besides, doesn't a parent think that their child is the cutest, smartest of the bunch? It's only natural that I think more of my gear than they do...

John
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Old 5th October 2006, 03:39 AM   #105
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Default It's been awhile...

I'm studying Nelson's earlier Zen offerings and have decided to attach the input buffer from Zen 4 onto my ZV7-T.

My question: Do I just use the buffer transistor and associated bias and filtering components, or do I also require Zen 4's feedback loop?

Hope all is well with everyone.

John
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Old 5th October 2006, 06:09 PM   #106
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You can just use the buffer, but it's worth noting that if you
run feedback back to the input of the buffer you can use
much higher impedances on the feedback network.

If you are running feedback back to the output of the buffer
you will still need series resistance at the output of the buffer.

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Old 6th October 2006, 12:46 AM   #107
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Default Thanks Nelson,

I'm drawn towards the idea of including the buffer in the feedback loop. Is is safe to cut and paste ZV4's front end and associated values to ZV7-T's gain Fet?

I realize that it's showing nerves of jello to ask that question; I should build it, plug it in and see what happens. It would be nice to avoid burning up another set of Fets, though. I've destroyed a half-dozen pairs so far.

I'm also planning to run the 47 ohm resistors from output to ground and swap the iron-core choke for air-core. Since this is a high-frequency amp (400hz and up), I can get away with smaller chokes.

This project is great fun, Nelson, and I can't thank you enough for your support of the BAMs out there (backyard-amp-mechanics). BAM is also what my amp sounds like when I let out the magic smoke...

John
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Old 14th October 2006, 04:56 AM   #108
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Default My revisions:

All comments welcome.
Attached Images
File Type: jpg zv7-t newest.jpg (71.1 KB, 194 views)
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Old 14th October 2006, 05:12 AM   #109
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I've ordered 80lb. of 16AWG copper wire to fabricate the air-core chokes. I'm starting off with 50mH per leg since this amp is to be used over 400hz.

R-13 is my best guess. I'm a rank amateur at this stuff. Fabricating is what I do best.

I've ordered 100 IRFP044N transistors cause I want to hear what the little fellows sound like; this is why I lowered the input voltage, not to mention I run a 110 db horn from 400hz to 20k. I don't require 30 watts...

Right side of schematic is a mirror of left, hence no values entered.

I'll begin revamping my project this weekend.

John
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Old 14th October 2006, 06:26 PM   #110
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Default by the way...

I treated the ZVP3310 like a LED and biased it accordingly. Like I said previously, I'm just an amateur at this. I think Nelson is biasing this transistor at 8 mA, so I adjusted the bias resistor to the lowered 22.5v voltage to match the 8 mA figure.

This is so elementary to the EEs here, sorry...

John
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