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DIYstompboxes.com  |  DIY Stompboxes  |  Building your own stompbox  |  MPSA13 -> ? 0 Members and 1 Guest are viewing this topic. « previous next »
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Author Topic: MPSA13 -> ?  (Read 1712 times)
JimRayden
Posts: 1986


Estonia


WWW
MPSA13 -> ?
« on: May 17, 2005, 03:32:47 PM »

I'm starting a Whisker Biscuit and can't find the damn wierd thingy called MPSA13 anywhere.

It's a darlington, right? Would two 2N5088's work instead?

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Jimbo
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lightningfingers
Posts: 737


MPSA13 -> ?
« Reply #1 on: May 17, 2005, 03:35:53 PM »

you can use 2 NPNs, that will work just fine  :wink:
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U N D E F I N E D
David
Posts: 2152

David M


Re: MPSA13 -> ?
« Reply #2 on: May 17, 2005, 08:32:52 PM »

Quote from: JimRayden
I'm starting a Whisker Biscuit and can't find the damn wierd thingy called MPSA13 anywhere.

It's a darlington, right? Would two 2N5088's work instead?

-----------
Jimbo


Jimbo, did you check Small Bear or Mouser?  If you need to sub, try looking for a MPSA14.  It's a '13 on steroids, I'm told.
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Ben N
Posts: 3376

Ben N. - really! Now Israel, once Baltimore


MPSA13 -> ?
« Reply #3 on: May 17, 2005, 10:40:07 PM »

I got some on ebay, from dpi4parts (Dan Peters) IIRC.

Ben
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brett
Posts: 3816


MPSA13 -> ?
« Reply #4 on: May 17, 2005, 11:16:34 PM »

Hi.

MPSA13s and 14s that I've tested all go hFE greater than 30,000 (typically 35,000).  So the specs (10,000 and 20,000 Huh) don't seem to matter anymore.

Instead of 2N5088s, you might try 2N3094s or PN100s, or even some power devices for a more modest hFE (2 x BD139s should get you about hFE=15,000)

have fun
(The WhiskerBiscuit is a great project).
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Brett Robinson
Let a hundred flowers bloom, let a hundred schools of thought contend. (Mao Zedong)
JimRayden
Posts: 1986


Estonia


WWW
MPSA13 -> ?
« Reply #5 on: May 18, 2005, 05:57:00 AM »

Well, I'm in Europe and can't actually order them from mouser or such. I just discovered I can order MPSA14 in the local store. But conveniently I have a pile of 2N3904's and 5088's to use. Any noticable sonic difference?

Also, how to smooth off the fuzzyness? I just used a Creamy Dreamer and it sounded sweet! Real wide controls from slight fuzz to santana-like cream. I want that heavily compressed cream in my box. Will WB's own tone control do the trick?

This is gonna be swee-tah!

EDIT: A gain control too, please. Smiley

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Jimbo
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B Tremblay
Posts: 1548

runoffgroove.com


WWW
MPSA13 -> ?
« Reply #6 on: May 18, 2005, 07:18:14 AM »

You can roll your own darlington using this diagram:



There shouldn't be any audible difference.

Add the optional 47pF caps for the velvety sound.

The guitar volume does a good job of controlling the gain.
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B Tremblay
runoffgroove.com
Albert Kreuzer
Posts: 15


WWW
MPSA13 -> ?
« Reply #7 on: May 18, 2005, 08:11:17 AM »

Hi Jim,

since you are in Europe, maybe you can get a BC517 (npn Darlington)? I just built a whisker biscuit last week with BC239 instead of 2N5088 and a BC517 instead of the MPSA13 and it works just fine!

To decrease "fuzziness", try to increase the 47p caps across the transistors (maybe 470p).

Cheers,
Albert
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Everything works until it doesn't.
JimRayden
Posts: 1986


Estonia


WWW
MPSA13 -> ?
« Reply #8 on: May 18, 2005, 08:34:08 AM »

Thanks, Mr.B, I've seen that trick before. I don't think the guitar volume would be too good of a solution in the case where I want to turn the pedal on for a solo (and don't need the whole pack o' gain). I would simultaneously have to push the switch and turn the vol knob down. You never hit the right guitar vol the first time (especially when you have the metal knobs with no numbers), so in my opinion a gain knob would be necessary for all the pedals used for soloing.

Oh, and about the velvety sound, I'm guessing the additional caps turn the pedal smooth in all its range. I'd like to have the tone control (or an additional control) to go the whole way from screamin' fuzz to muffled clean Santana.
As you see, I'm in love with the Creamy Dreamer and wouldn't accept much less from my muff-type pedal. Smiley

Also, the CD seems to allow an enormous volume gain since the output is equal with the clean when the vol knob is somewhere about 8-9 o'clock. Does WB also do that?

Oh and thanks Al, I found the 517 from the local store.

-------------
Jimbo
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B Tremblay
Posts: 1548

runoffgroove.com


WWW
MPSA13 -> ?
« Reply #9 on: May 18, 2005, 08:45:53 AM »

Seems like you could buy a Creamy Dreamer instead of attempting to reinvent the Whisker Biscuit as one.  Or, build a BMP and incorporate some of the countless mods that have been documented here and elsewhere.

At the very least, you should breadboard the WB and determine whether it can do the job.

To be perfectly frank, it's somewhat uncomfortable for a developer to field requests for mods to a circuit when the builder hasn't even tried out the stock version.  Have some faith in the developer's choices.

You can add a 250k pot at the front of the circuit as a pre-gain control if you need a preset lower level of gain.  However, the stock amount of gain may be acceptable to you.  Breadboard it and see!
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B Tremblay
runoffgroove.com
JimRayden
Posts: 1986


Estonia


WWW
MPSA13 -> ?
« Reply #10 on: May 18, 2005, 08:56:02 AM »

I was just about to grab my perboard and try out the thing. I'll see if it works for me. Thanks.

PS: Wich ones are better to use for the homebuilt darlington, 2N3904 or 2N5088?

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Jimbo
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nightingale
Posts: 617

RyanS - Denver, Co


WWW
MPSA13 -> ?
« Reply #11 on: May 18, 2005, 08:57:41 AM »

FWIW,
I play a whisker bisquit in my line. I ended up with a 220k resistor wired to the input, and a 10k "fuzz" pot wired as a variable resistor to ground from the emitter of the darlington. this gives me a very good clean up with the "fuzz" pot at it's minimal settings.

i gave my 1st WB away to an established rocker friend, it had the "velvet" caps.. he told me it was the best gift anyone ever gave him!

the WB i recently built for myself was without the velvet caps.. it is a little more raggedy sounding to my ears.

do you built the pedals sold on the site im your signature?
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JimRayden
Posts: 1986


Estonia


WWW
MPSA13 -> ?
« Reply #12 on: May 18, 2005, 09:42:23 AM »

The link is to my brother's web community/audio store page, he's a reseller. If I remember correctly, the ones up at the store are being built by a member of this forum.

Thanks, I'll try your mods.

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Jimbo
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