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Author Topic: Perfboard layout for Marshall Lead 12 Preamp  (Read 11449 times)

pyromaniac_

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Perfboard layout for Marshall Lead 12 Preamp
« on: March 08, 2010, 07:02:44 AM »
I made a perfboard layout for the Marshall Lead 12 preamp last night, so I thought I'll post it here if anyone might found it useful. In the original schematic the supply voltage was +/-16, but I added two zener diodes and resistors
to make it possible to run the preamp at +/-35 V (yes the it will only be 15 V after the zener but it should work). I also decided to use the original wiring for the input jacks, which I found hard to draw in DIYLC, so look at the original schematic to figure it out.

I find it really hard to draw a satisfying layout by hand, so please tell me what you think about my layout so I can do better next time.

J M Fahey

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Re: Perfboard layout for Marshall Lead 12 Preamp
« Reply #1 on: March 08, 2010, 09:43:35 PM »
Hi Pyromaniac.
It looks perfect to me. :)
So far I found no mistakes, (waybe somebody with keener eyes does).
Build it, if you haven't already, and hook it to any power amp, from TDA2003 to TDA7294.
Sound will be very good.

pyromaniac_

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Re: Perfboard layout for Marshall Lead 12 Preamp
« Reply #2 on: March 09, 2010, 01:27:38 AM »
Ok, good to know, thanksa for the feedback. Well, I'm quite satisfied with the layout so far, maybe I'm just paranoid. The first amp I build, also using perfboard, got the unwanted feature to produce a really loud sawtooth wave then the volume knob was turned to min. Quite annoying to almost blow the speaker, and your ears then the volume knob was turn down a bit to much. I still haven't figure out why this happened, except that it probably was because of the layout rather than the circuit and/or the components used. Maybe the grounding was wrong or something. However I don't wanna make that mistake again. The grounding in this layout won't be a problem what I can see.

I was actually thinking of building it with a TDA2003 chip. If a use the TDA2003 as power amp, I don't need the zenerdiodes cause I'll run all at +/-16 V too. Got an extra transformer, 2x12 V 1,5 A, which should to the trick.

pyromaniac_

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Re: Perfboard layout for Marshall Lead 12 Preamp
« Reply #3 on: March 09, 2010, 06:59:45 AM »
Sorry, meant TDA2030. Which is chip with the lowest output power, but still can be run at +/-16 V I've found. TDA2003 can't be be used with an dual power supply as far as I know.

tpb03

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Re: Perfboard layout for Marshall Lead 12 Preamp
« Reply #4 on: January 16, 2013, 08:02:10 PM »
Sorry to drag up this old thread. Has anyone got a copy of the original layout? The file in the original post is not displaying for me.

Cheers

Tim

Roly

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Re: Perfboard layout for Marshall Lead 12 Preamp
« Reply #5 on: January 16, 2013, 08:56:03 PM »
Seems to download okay, but gives "unsupported PNG format" error in IrfanView.  :(
If you say theory and practice don't agree you haven't applied enough theory.

J M Fahey

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Re: Perfboard layout for Marshall Lead 12 Preamp
« Reply #6 on: January 16, 2013, 08:57:18 PM »
Unfortunately the original file is corrupted and unrecoverable.
Sorry.

PM the designer, maybe he kept an original.

meffcio

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Re: Perfboard layout for Marshall Lead 12 Preamp
« Reply #7 on: October 10, 2014, 10:48:37 AM »
Quote
Hey,
What old thing... sure. It still works surprisingly good actually. I attached what I found. Feel free to reupload it at the forum if you like too.
best regards

meffcio

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Re: Perfboard layout for Marshall Lead 12 Preamp
« Reply #8 on: October 10, 2014, 11:50:13 AM »
I also made my own vero layout, but it's kinda my 1st layout ever. Would you guys mind checking it for errors?

tpb03

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Re: Perfboard layout for Marshall Lead 12 Preamp
« Reply #9 on: October 13, 2014, 10:13:48 PM »
Great, thanks Meffico and Pyromaniac.

I'll have a go at building and report back. I might try both perf and vero layouts.

Tim

 

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