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Analog Line Level Preamplifiers , Passive Pre-amps, Crossovers, etc.

Doug Self Preamp from Linear Audio #5
Doug Self Preamp from Linear Audio #5
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Old 10th April 2017, 05:09 PM   #711
scottjoplin is offline scottjoplin  Wales
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@ Eldam.
Have you got it up and running yet? Bi-polar caps are only mandatory at the inputs (marked NP on the schematic)
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Old 10th April 2017, 07:32 PM   #712
Eldam is offline Eldam  France
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Yes, Muses everywhere on the main board ! (as BOM !)
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Old 10th April 2017, 07:48 PM   #713
jan.didden is offline jan.didden  Europe
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Quote:
Originally Posted by Eldam View Post
Yes, Muses everywhere on the main board ! (as BOM !)
I think we should realise that that is not Doug's BOM.

Jan
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Old 10th April 2017, 08:14 PM   #714
Eldam is offline Eldam  France
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I believe it diserves some others caps at power positions on the pre pcb for a "less" thin sound !

I saw some used Nichicon FK serie for the biggest caps of the pre board, I believe there is better to do .

YMMV, my amp and speakers are very on the clear side already !

Nich. KG for the PS board is a very good decision; I will change the others 100 uF caps of the the Power boards ! But it's a detail and I had no time to tweak the sound for my tastes/own system...

Last outrages to drosophiles as the design is good enough

Thanks to Doug & Carl
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Old 10th April 2017, 08:30 PM   #715
scottjoplin is offline scottjoplin  Wales
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I should have mine up and running in the next few days. I'm waiting on some pcb screw terminals for the I/O link, I didn't like the 20way idc connectors specified in the BOM. I was thinking of hard wiring between the boards but this is impossible with them in situ and tricky otherwise. Also I'm going to use a supply that's already powering my active crossover. Do you think you'd be able to hear the difference with polarized caps? It will be interesting to see what graemed says after he's built his.
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Old 10th April 2017, 09:29 PM   #716
Eldam is offline Eldam  France
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That's what I did between the main and I/O board : copper silver plated with PFTE suround! More by faith than benchmark, as most of the time it is what I use for my diy dacs.

My understanding is the flat cable for the select board rotary pot is not seing any signal ! Just for selecting the relays.
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Old 10th April 2017, 09:35 PM   #717
scottjoplin is offline scottjoplin  Wales
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Yeah saw your hardwiring, good idea. Seeing those long ribbons people were using with the connectors....no way Jose! Input selector not an issue. That will be a novelty for me, for years I've had to unplug and plug to select inputs!
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Old 11th April 2017, 01:52 PM   #718
ruckin is offline ruckin
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I have a capacitor placement question. Looking at the schematic I see that the pins of C42 and C43 seem to be directly connected to a 3K3 resistor. C42/43 have multiple holes in the board. In the BOM I have the capacitors in both of these locations are the same. Unfortunately I am about 3000 miles away from my board this week so I am unable to confirm/check but either C42L or C43R (sorry can't remember which one) when I flip the board over it does not seem to directly connect to the R42 (or R45) resistor.

It seems like the board hole alignment for one of these capacitors is not how I would expect it to be. Am I mistaken in my understanding or is the marking on the circuit board not correct?
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Old 11th April 2017, 02:04 PM   #719
scottjoplin is offline scottjoplin  Wales
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You are right, I found one of the capacitor markings on the board to be incorrect.
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Old 11th April 2017, 04:18 PM   #720
DouglasSelf is offline DouglasSelf  United Kingdom
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Quote:
Originally Posted by Eldam View Post
I believe it diserves some others caps at power positions on the pre pcb for a "less" thin sound !

I saw some used Nichicon FK serie for the biggest caps of the pre board, I believe there is better to do.

YMMV, my amp and speakers are very on the clear side already !

Nich. KG for the PS board is a very good decision; I will change the others 100 uF caps of the the Power boards !
As the designer I think I have the right to say that this is a waste of time & money.
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Last outrages to drosophiles as the design is good enough

Thanks to Doug & Carl
Last outrages to fruitflies ??? Lost on me.
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