Seymour Duncan Lava box  [schematic]

All about modern commercial stompbox circuits from Electro Harmonix over MXR, Boss and Ibanez into the nineties.
Post Reply
User avatar
cpm
Resistor Ronker
Information
Posts: 276
Joined: 29 Oct 2008, 09:55
Location: spain
Been thanked: 50 times

Post by cpm »

This is a nice pedal, not expensive and can be faound cheaper os second hand

A rotary 6 position switch to select some caps for tone shapping and amount of gain.
Two bimos opamps driven into saturaion
I was suirprised at how effectively it cleans with input volume variations, very sensitive.

Most of the component are smd, so no values for the smd caps. Component names match those on the pcb.
Attachments
sd_lavabox_traced.png

User avatar
coldcraft
Diode Debunker
Information
Posts: 725
Joined: 11 Jul 2009, 01:00
Has thanked: 38 times
Been thanked: 85 times

Post by coldcraft »

interesting design. I wonder how it would sound using TLC2262 Dual Opamp, like the tech21 designs.
Black Dynamite wrote:you need to shut the fuck up when grown folks is talkin.

User avatar
Chugs
Resistor Ronker
Information
Posts: 277
Joined: 16 May 2009, 09:47
Has thanked: 63 times
Been thanked: 47 times

Post by Chugs »

coldcraft wrote:interesting design. I wonder how it would sound using TLC2262 Dual Opamp, like the tech21 designs.
I thought the same thing.

I wonder how much of an effect the compensation caps are having on the sound.

User avatar
J M Fahey
Information
Posts: 10
Joined: 08 Jan 2009, 21:13
Has thanked: 1 time
Been thanked: 1 time

Post by J M Fahey »

You mean the switchable caps?
It's similar to Orange's FAC control: small caps ahead of the distortion cutting some bass to make it less muddy.
Going from 1 to 6 they have less and less effect; in the last one (what they call woman tone) all sound goes through as-is.
It has no diodes, Fets , Leds or any other clipping device, just the 2nd Op Amp gets banged against the rails (+9V and ground).
I liked it, although the sound is not really tubey buy like a *good* SS amp driven balls to the wall.

User avatar
Chugs
Resistor Ronker
Information
Posts: 277
Joined: 16 May 2009, 09:47
Has thanked: 63 times
Been thanked: 47 times

Post by Chugs »

I used to have an Orange OR120. It was a pretty good amp.

I was talking about the compensation caps across pins 1 and 8 of the opamps not the switchable caps.

User avatar
Throbb7
Information
Posts: 9
Joined: 15 Feb 2012, 20:25
Has thanked: 6 times
Been thanked: 1 time

Post by Throbb7 »

Looks like a good place to start if you want to try adding some diodes in the feedback loop, or to ground. :block:

User avatar
jonny4rd
Information
Posts: 19
Joined: 18 Dec 2010, 18:54
Has thanked: 1 time
Been thanked: 7 times

Post by jonny4rd »

What could I change to add more gain and/or smooth out the drive?

User avatar
roseblood11
Tube Twister
Information
Posts: 1887
Joined: 23 Aug 2008, 14:21
Has thanked: 366 times
Been thanked: 313 times

Post by roseblood11 »

Would be great to know the missing cap values. Does anybody own this pedal?

User avatar
dorrisant
Information
Posts: 31
Joined: 08 Sep 2010, 14:48
Has thanked: 53 times
Been thanked: 5 times

Post by dorrisant »

roseblood11 wrote:Would be great to know the missing cap values. Does anybody own this pedal?
Actual in-circuit values:
C4= 2n5
C5= 312p
C6= 25n
C7= 90n
C8= 2n2
C10= 2n2
C11= 1µ
C14= 312p

Post Reply