Next Build: BYOC's New Overdrive 2 Kit...

[duhvoodooman***]

I am confused by the above. I am interested in hearing the TS spec pedal, and knowing how the hybrid works. But basically I am lost in sorting it out at this point. I think a really versatile TS type pedal would be awesome. I like the MOSFET clips, but I am wondering how the TS setup sounds. Not saying you have to build one to show us, but just sayin'. All the sounds are great so far!:

Apparenly I created some confusion with my non-specific language, so let me clear this up.

The BYOC Overdrive 2 is still very much a Tube Screamer TS8080 circuit clone. The basic overdrive circuit is the same one that's in the original BYOC Overdrive, and the one my ZYS pedal is based upon. It also includes a separate booster stage within the same enclosure, fully independent of the overdrive. This booster would behave no differently if it was in a separate pedal enclosure located the next spot down in your pedal chain.

It is still possible to build the overdrive portion of the OD2 as an exact circuit replica of the original BYOC Overdrive, if what you want is the closest thing you can make to a vintage TS808, period. What the OD2 adds is options. Options for how it's built, and options for how you operate it.

One of the options for the build is the MOSFET conversion. All this does is allow you to replace "stock" TS components (mostly bipolar NPN silicon transistors) with a different type of transistor known as a metal oxide semiconductor field-effect transistor, or MOSFET. There are 5 places these can be used. One of them is in the booster stage, so let's just forget about that one and concentrate on the overdrive portion, where the other 4 are located. These are: the input buffer, the output buffer, the clipping stage, and the operational amplifier (opamp). The first three all use a discrete MOSFET known as a BS170. The opamp, however, uses MOSFET technology built into an IC chip. As I understand it, most opamps used in effects pedals use JFET (junction field-effect transistor) or bipolar transistors, and MOSFET opamps are much less commonly found in these applications. Don't ask me why--I have no idea. In any case, MOSFETs have different properties than other transistor types, which are reflected in somewhat different tonal characteristics. Because MOSFETS also have internal diodes, they can be used as signal clippers. In this role, they're known for having a somewhat warmer, smoother sound than the commonly used silicon diodes such as the 1N4148 or 1N4001.

In any case, you can use the MOSFET components in all, some or none of those four places in the OD2 overdrive circuit. Use none, and you're building to "TS specs". Use them in all four places, and you have a full MOSFET overdrive conversion. Use it in some places and not others and it becomes a hybrid. In point of fact, the tonal impact of their use is most apparent in the clipping section, and quite subtle elsewhere. AAMOF, if you listen to certain audio clips posted here recently (hint, hint), it's a comparison between the 3 different opamps provided with the OD2 kit--one MOSFET and two non-MOSFET--that you're hearing. The differences aren't big, to say the least. The impact of the MOSFETs in the two buffers is more subtle yet. There, the primary effect is to raise the impedance, which helps preserve top-end response. But the impedances are already quite high with the stock transistors, so there's little if any real audible impact there.

There are a couple of other choices you can make as far as the OD2 build options go, but the other options with real tonal impact come from features added to the OD2 to let you change the way you run it. These include:

• Two switchable clipping choices as well as a "diode lift" setting that passes the signal through unclipped.
• Three bass response settings: stock (Normal), more (Full), and more yet (Fat).
• Three internal trimpots to adjust minimum gain, maximum gain, and the output level of the second stage of the opamp ("Louder" trimpot). You have to be a little careful about the max gain setting, because it also affects the bass response. And the Louder pot will affect the sensitivity of the pedal's Tone control.

Bottom line: whether you build to stock, MOSFET or in-between (hybrid) specs, the pedal still has a lot of tonal flexibility from these other features. Not quite as much as my ZYS, where you have the max. gain as an external control and more range on the bass control, as well as 3 different clipper choices, but still much, much more flexibility than a TS808 offers. Or most other overdrive pedals, for that matter.

Hope that helps fill in the blanks....

[duhvoodooman***]

Here's the graphics design I've put together for the non-MOSFET version of this pedal:

[tunghaichuan***]

Sweet! :

You really have a talent for developing graphics for pedals, DVM. :

tung

Here's the graphics design I've put together for the non-full MOSFET version of this pedal:

[duhvoodooman***]

You really have a talent for developing graphics for pedals, DVM.

Thanks for the encouragement, Tung!

Here's the MOSFET conversion counterpart, with a tip of the hat to Tot for a great name idea:

[tunghaichuan***]

Again, very cool. :

tung

Thanks for the encouragement, Tung!

Here's the MOSFET conversion counterpart, with a tip of the hat to Tot for a great name idea: