Dr_J

Re: [BUILD] K13117 (ClassA MicPre by Darius Kubarth / Kubi)
« Reply #40 on: December 18, 2013, 04:38:19 PM »
Hi every one,

still working from time to time on this build.

I just mailed with Volker about wiring the Gain switch.
On the PCB are 2 connections labeled RG1 and RG2, these are
Ra and Rb in the Gain PDF "Widerstandstabelle für die Wahl der Verstärkung".

In a nutshell:
RG1 = Ra
RG2 = Rb


Wiring the 2 pol Gain switch, e.g.:

20db Gain -> Ra = 31623Ohm, Rb = 47000Ohm (Calculated Values, page 1)
Ra = 31623Ohm ~  33kOhm parallel with 820kOhm
=> 1/(1/33kOhm + 1/820kOhm) = 31723Ohm (Resistor Error ~0.3%) (Page 2)

So, Ra has to be made out of 2 Resistors in parallel at the first row of the switch!?
([email protected] Row #1: 33k || 820k, Row#2: 47k)

A'm I right Volker?


ROCK-ON!
« Last Edit: December 29, 2013, 05:45:32 PM by Dr_J »


[silent:arts]

Re: [BUILD] K13117 (ClassA MicPre by Darius Kubarth / Kubi)
« Reply #41 on: December 19, 2013, 03:44:12 AM »
Yes, if you want to limit yourself to E12.
I would just take one 31K6 resistor out of E48  ;)

Dr_J

Re: [BUILD] K13117 (ClassA MicPre by Darius Kubarth / Kubi)
« Reply #42 on: December 19, 2013, 05:24:54 AM »
Aaaaaaaaaaaaaaaaa...............    >:( >:(

It was too late at night...
Thanks for the hint!

Now I have a pile of unused resistors laying around...  :D
...and have to order some resistors...


ROCK-ON!
« Last Edit: December 19, 2013, 06:08:35 AM by Dr_J »

Dr_J

Re: [BUILD] K13117 (ClassA MicPre by Darius Kubarth / Kubi)
« Reply #43 on: December 29, 2013, 04:02:32 PM »
... fired it up right now the first time... no smoke  :D
.. voltages are fine... and we've a nice "Tonfrequenz Verstaerkung" on both channels...  ;D  GREAT!!
... and dead quiet!

Where's my beer.... and my DIY booze...  ;D

ROCK-ON!


P.S.: Pix coming soon...
« Last Edit: December 29, 2013, 05:44:53 PM by Dr_J »

100WChris

Re: [BUILD] K13117 (ClassA MicPre by Darius Kubarth / Kubi)
« Reply #44 on: December 30, 2013, 05:50:02 AM »
Cool, another one joined the small club!
The K13117 became instantly my favorite pre for bassguitars! Thinking about building some Harrison Ford Filters: i need some low-cut-filters now  :D


Dr_J

Re: [BUILD] K13117 (ClassA MicPre by Darius Kubarth / Kubi)
« Reply #45 on: December 31, 2013, 02:18:03 PM »
Hi Chris,

funny, when i play a bit around with the unit i although plugged a bass in my new BoHansen DI and into it... :)

Well how small is the club?!  ;) 

ROCK-ON!

Dr_J

Re: [BUILD] K13117 (ClassA MicPre by Darius Kubarth / Kubi)
« Reply #46 on: December 31, 2013, 02:20:51 PM »
Hi,

when switch through (up and down) the gain steps from time to time the unit is dead for a minute or so. Sometimes switching phase helps...
Any ideas?

I'll have to do some more testing...

ROCK-ON!

Dr_J

Re: [BUILD] K13117 (ClassA MicPre by Darius Kubarth / Kubi)
« Reply #47 on: January 16, 2014, 04:07:54 PM »
Here we go...  ;D

Front panel, as nearly always, from Frank (NRG).

ROCK-ON!
« Last Edit: January 16, 2014, 04:12:52 PM by Dr_J »

Dr_J

Re: [BUILD] K13117 (ClassA MicPre by Darius Kubarth / Kubi)
« Reply #48 on: January 16, 2014, 04:11:34 PM »
... and the guts...

I've used only white leds, they're very bright shining... maybe I'll play around with some higher resistors to lower current.
We'll see...  ;)

I had to lay down all capacitors to fit it all in 1HE case.
And of course i found out nearly after finishing soldering... grrrr...  :)

I although had to cut the heat-sinks to fit, temperature seems to be still ok. 

ROCK-ON!

« Last Edit: January 16, 2014, 04:21:14 PM by Dr_J »

[silent:arts]

Re: [BUILD] K13117 (ClassA MicPre by Darius Kubarth / Kubi)
« Reply #49 on: January 16, 2014, 05:08:19 PM »
Creative and nice  :) :) :)


funkymonksf

Re: [BUILD] K13117 (ClassA MicPre by Darius Kubarth / Kubi)
« Reply #50 on: January 22, 2015, 04:35:43 PM »
I'm very interested in building a stereo pair of these pre-amps. Has anyone utilized a potentiometer instead of a 2x24 switch? I'm curious what value and type (log or linear) I should use. I really am insecure about doing my own switches, so any advice on what values i should use helps to. I've spent two hours looking for advice on stepped switch wiring with little luck, the only source I found was for stereo attenuators for volume control.. Is it the same idea for gain control in a mic pre?


 

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