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Modding the LPB-1

PostPosted: Fri Aug 14, 2009 1:32 pm
by rbtr
Since my cc/dc has replaced my LPB-1, and knowing that it won't go for much on the used market, and always wanting a "treble booster." I figured I could mod my LPB-1 to screaming bird specs. Has anyone else done this?

I looked up some info, and found that I need to replace the 2 0.1uF capacitors with 0.002uF capacitors. I open it up and there's 3 and they are all the same value, but also read that I need to change the caps that interact with the transistor, so I'm assuming, in this case the two right beside the transistor are the ones that need changing. Doing a quick search for parts leads me to finding only 0.0022uF caps, are those the same things? Also is important what kind of cap I get (electrolyte, film, ceramic.) They look like film caps, should I replace them with film caps?

And my final question, how hard would it be to wire this to a 2 way switch, that would allow me to switch between the 2 values?

I guess these would help some?
Screaming bird schematic
LPB-1 schematic

thanks in advance :thumb:

Re: Modding the LPB-1

PostPosted: Fri Aug 14, 2009 1:39 pm
by Scruffie
Just replace the input and output caps (follow the switch wires) with the new values to take it to the screaming tree and ceramic will work fine, some claim film sound better and technically they are more suited to audio but Ceramic will work fine, electrolytic are polarized and are of far larger values so don't use these or tantalums as they are also polarized, Film or Ceramic is what you want.

If you wanna learn about the LPB then go here http://www.beavisaudio.com/techpages/HIW/hiw1.gif

The third cap is just a variation in design, don't worry about it.

And Modding a switch to go between 2 components is easy, put a component on either end side of the 6 lugs and put the 2 middle lugs to where the original component went

Re: Modding the LPB-1

PostPosted: Fri Aug 14, 2009 1:56 pm
by rbtr
Using what kind of switch? a 3dpt? I think I can wrap my head around that
And .0022 is the same right? Basic math says so, if I rounded it off it would be, and this stuff operates on math, so this is a safe assumption, right?

Thanks :)

Re: Modding the LPB-1

PostPosted: Fri Aug 14, 2009 2:03 pm
by Scruffie
Yea 0.0022 will be fine, just a slight variation, values vary alot and have different tollerances so on, that's perfect.

No an DPDT would be fine original cap on one side, new cap on other side, if you used a 3PDT switch you could have an LED telling you it was the new value.

If you want both values to change on one switch though you'll have to use some math to work out the parralel capacitance and use completely different values.

Here's a diagram of how you'd wire the DPDT switch to just switch between the new and old cap though (hope this isn't getting too confusing)

Re: Modding the LPB-1

PostPosted: Fri Aug 14, 2009 2:09 pm
by rbtr
Ah, of course...well that math is probably more than I want to deal with.

Neat, thank you

Off to order parts now, should be fun!