Schematic and info avaiable HERE
Saturday, 5 September 2020
Yamaha OD-10MII Overdrive
An obscure old japanese ovedrive circuit that looks like your worst 80's metal pedal. But the reputation is pretty good and it has its small fanbase. And it is not a YATS.
Friday, 4 September 2020
Thursday, 3 September 2020
Little Jim
Found this cool little thing at DIYSB. A fairly simple high gain circuit which is supposed to emulate a cranked Marshall using three MOSFETS with a J FET buffer up front. There is a simple treble roll of at the end of the circuit.
Write-up, schematic and a demo HERE
Tuesday, 1 September 2020
Monday, 31 August 2020
Fuzzhead Fx Harmonic Gyrolator
Harmonic Percolator is one the coolest vintage dirtboxes out there with its simple yet unique design, its odd even order harmonics texture, odd mojo parts and it is also a very good overdrive with the gain control rolled back.
But using mostly humbucker equipped guitars nowadays it tend to be overly compressed and a bit muddy and dull. Started to tinker with it tso it would suit hot humbuckers but no dice. As it is an unique circuit like no other, the usual mods didn't work out very well like reducing input cap or add a resistor in line with the input signal.
But I stumpled upon Dead End Fx Splinter project whcih offers a sollution for this namely reducing the coupling cap value between the transistors and adding a cap across the base of Q1 and ground.
Later on I added a "Texture" control which techically is a resostat which alters the resistanse to ground for one of the clipping diodes. Most stock HP's has 4,7k resistor here for some assymetric clipping. I used a 10k pot so stock setting is at noon, turn it up and you get a more open and wide distortion, roll it back for some glithy compreesed sounds with sub octaves jumping around.
And I added a two band gyrator tonestack at the end with values not to far away from Boss HM2. The result is a quite lo-fi, fat, industrial and grim fuzz.
Sunday, 30 August 2020
Friday, 28 August 2020
Zencafe's Microtubes 2K
At first I thought this was an original Darkglass design but couldn't find any info on it except for the schematic. But it turns out it is a DIY designed project by zencafe at DIYSB. Schematic and info in this thread,
Looks like a fun and quite simple project which looks like a hotrodded Red Llama/Tube Sound Fuzz with some extra tonal options
Wednesday, 26 August 2020
Monday, 24 August 2020
Sunday, 23 August 2020
Lell Heavy Metal DEQ-700
Schematic avaiable HERE
The switch appears to a on/off selector for the distortion section so it can be used as a stand alone eq pedal as well.
Saturday, 22 August 2020
Lell EX-9 Exciter
Schematic avaiable HERE
Note that pot lug numbers isn't labelled in the schematic. And the pot tapers is unknown but my best guess is that they are linear.
This one seems to be a treble booster/light overdrive with a tonestack somewhat related to a parametric eq.
Friday, 21 August 2020
Sunday, 16 August 2020
Sunn Beta Pre Amp
Ok, let's release the beast. Two layouts. One stock for iether Bass or Lead cap values.
And another one with a Beta/Lead switch. Since I'm not a big fan of offboard wiring I decidied to simplify things a bit. Lead cap values is always in circuit and with a 4PDT switch you can switch in four caps in parallel so it matches up with Bass values. Some values differs in few hundred pico farad or a few nano farad but the overall difference is minimal. And in theory you could use a SPST switch....
It also has an onboard charge pump for 15v/-15 operation.
This going to be the last layout I will post in a while since I'm going back to work tomorrow but this and a few other layouts should keep some of you occupied....;-)
*Edit*
MTK once again outdid himself! Here is a short demo of Lead/Bass switch version.
Stock layout.
Xotic BB Pre Amp
Two layouts for this one. One stock and one with an additional Mid control. The clipping diodes is placed on the side of the board so you can easily add a diode clipper switch. Just omit the diodes on the board and add wires tat pad 1M and 1N to a DPDT switch where you solder your diodes of choice.
Stock layout






















