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Old 25th December 2008, 12:19 AM   #991
rob3262 is offline rob3262  United States
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Default Re: searching components for best quality/price rate

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Originally posted by AudioG
While I waited for the arrival of the pcbs, I am searching the components, so I have prepared a datasheet that could be useful to others.
Ciao, Giuseppe.
Giuseppe, your resistor values in the front end (R6 R7 R9 R10 etc) stray from Jens posted BOM, where you have specified 300R instead of 330R. Please explain this discrepancy.

As I'm ready to build up my first PCB, I need to know what effect (however marginal) this will have on function of the build.

Regards, Rob
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Old 25th December 2008, 12:22 AM   #992
rob3262 is offline rob3262  United States
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P.S. Merry Chrismas to Keith / et all
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Old 25th December 2008, 09:48 AM   #993
AndrewT is offline AndrewT  Scotland
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Default Re: Re: searching components for best quality/price rate

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Originally posted by rob3262
Giuseppe, your resistor values in the front end (R6 R7 R9 R10 etc) stray from Jens posted BOM, where you have specified 300R instead of 330R. Please explain this discrepancy.
300r is specified by Leach and discussed in detail in the section covering linearity of the input stage and how degeneration influences this.
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Old 25th December 2008, 10:14 AM   #994
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Default Re: Re: Re: searching components for best quality/price rate

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Originally posted by AndrewT

300r is specified by Leach and discussed in detail in the section covering linearity of the input stage and how degeneration influences this.
Merry X-mas....

I chose the 330 Ohm value as this is a standard E12 type.... 300 Ohm may not be as easy to get....

\\\Jens
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Old 25th December 2008, 10:25 AM   #995
AndrewT is offline AndrewT  Scotland
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Hi Jens, Rob & AudioG,
There's nothing wrong with adopting 330r for 300r in the input stage, It's only 10% after all.

Rob asked, why AG reverted to 300r and it appeared that Rob had not bothered to read up on the Leach. Prof Leach gave us all this good design info for free and yet some refuse to read it.
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Old 25th December 2008, 11:16 AM   #996
clm811 is offline clm811  United States
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Default Merry Christmas!

Hi All!

Just wanted to say I'm now home recuperating and everything is fine(except I have to stay off my foot for a few weeks-darned crutches!).
Thanks for the kind wishes.

Also, I got another pair of PCB's(since I'd already started soldering components on mine, I didn't have an empty board to use for indexing the heat sinks!), and all the heat sinks in the current order are spoken for.

I wish all my friends* here a Merry Christmas/Hanukkah, etc, and a Happy New Year!!

-Chas

*special greetings and thanks to Jens, Tad, Ray, Carl, Fred and Bill
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Old 25th December 2008, 12:38 PM   #997
rob3262 is offline rob3262  United States
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Quote:
Originally posted by AndrewT
Hi Jens, Rob & AudioG,
There's nothing wrong with adopting 330r for 300r in the input stage, It's only 10% after all.

Rob asked, why AG reverted to 300r and it appeared that Rob had not bothered to read up on the Leach. Prof Leach gave us all this good design info for free and yet some refuse to read it.
There's a lot of information to absorb on this project, and many sources for reference material. I will re-read Mr. Leach's documentation, thank you Andrew for pointing me back to this source.
With regards,
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Old 28th December 2008, 10:00 PM   #998
rob3262 is offline rob3262  United States
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Exclamation thermal track pcb

I noticed that the Thermal tracking diode PCB's in this latest group buy are plated thru-hole to unmasked pads on the bottom side.

As seen in the PCB photo on Jens' Delta-Audio website, the pads should have been omitted. These bottom side pads can short out to the heatsink when mounted.

So, best way to remove the pad? Take Exacto knife and scrape 'em off, or hit it with a hot iron until the pads lift?
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Old 29th December 2008, 01:12 AM   #999
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rob3262,

Based on post 662 and 666, Tad and Bob mentioned that as long as the diode lead doesn't protrude, it should be fine. They didn't mention about the pads. See picture attached from Delta-Audio website. I hope that helps.
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Old 29th December 2008, 01:57 AM   #1000
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The first batch of boards did not have pads on the bottom of the diode boards. It sounds like a manufacturing error since Tad just reordered - the first I've heard of from Advanced. Maybe they'll give us a break on the next buy.

I'll grind the pads off with a Dremel. If you have a sheet of mica or some Kapton tape, you can just insulate them.
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