September 29, 2020 at 1:29 pm #15007
Woot! Woot! I just finished testing m’latest GuitarPCB Rat Deluxe build and after hearing the difference between the Reutz mod (using the trimpot) and not, I’m very tempted to build another in a larger enclosure and add the Reutz mod as an external toggle switch AND add an expression jack to supplant the Gain (Distortion) pot. Here’s why . . . . .
I first tested the pedal with the Reutz trimpot all the way down (counter-clockwise) and it sounded like a standard Rat. Cool. But when I turned the Reutz trimmer all the way up (full clockwise) I noticed a ‘high-pitch artifact’ in the signal with the Gain (Distortion) pot turned fully counter-clockwise. (The Filter pot was turned all the way up and the Volume was set at 12:00) As I played some rock chords (something Ted Nugent-ish) I slowly started turning up the Gain (Distortion) pot and got a very pleasant up-sweep in that ‘high-pitch artifact’ – as the Gain was slowly being turned up, that ‘high-pitch artifact’ started sweeping (filter-like) downwards as the distortion increased. Almost “wah-wah-ish”. The ‘high-pitch artifact’ was present with all clipping option settings, but most notable with the clipping set to “Off”.
I musta played with the pedal for an hour, loosing track of time, and was very pleased to hear how wildly versatile this build is with the various settings of the pots and clipping options. The sounds ranged from the very dark & doomy original Rat to some seriously great distortion – all with plenty of gain on tap. With the Volume (Level) set at anything past mid-point, the push into the the amp just got meatier and heavier. With the Volume (Level) set past mid-point, chords started to get ‘muddier’, but a GOOD mud.
So, in my excitement over the results of this build, I decide to post before I actually finished the enclosure. The artwork on it in the photos is just paper copy of the decal I’ve already made. I tried three different opamp chips, a plastic DIP LM308, a can uA308, and a plastic DIP OP07. I could distinguish zero difference in the resultant sounds of the pedal with each chip at any settings. The diodes used are a pair of NOS OA192 Ge with Fvd of ~0.8v and a pair of UV LEDs with a Fvd of ~1.0v
Now, on to the circuit porn and build shots . . .
Completed gutshot . . . .
Gut-stuffing planning (pre-wiring) . . . .
Thanks for looking! Happy building!September 29, 2020 at 3:46 pm #15010BarryKeymaster
Thanks for the details and posting.
Are you going to create a “service hole” on the lid for the LED 3PDT Vari-Brite board?September 29, 2020 at 7:15 pm #15014
Barry: “Are you going to create a “service hole” on the lid for the LED 3PDT Vari-Brite board?”
Ooh! I hadn’t thought of that. Great Idea! I have some of those small hole plugs that would be perfect for that purpose. Thanks!October 12, 2020 at 11:24 am #15228MattParticipant
Mark several of the production boutique Rat offerings put the Reutz mod pot on the face. I’ve built a few and mounted them as well. And while I like the occasional tonal tweak, overall I haven’t found it to be super useful. Perhaps if some components were adjusted to make the sweep a little wider then it would be more advantageous… Just my thoughts. YMMV.October 12, 2020 at 1:05 pm #15230
Matt – I get that. (But I didn’t that until after I but this one. So this one will go out as is.) I was examining the schematic and it appears that the R\C components on the tail of the feedback-loop (see image) are the primary difference between the Barry’s Rat circuit and the original. So, I’m guessing that futzing with those values may yield a wider sweep with an expression pedal on the Reutz pot. For now, further testing on this concept is at the bottom of my build queue, but IS in my build queue none-the-less. I’ve just not decided if I’ll stuff the entire circuit into a wah enclosure or use a dedicated external expression pedal. When I get there, testing will reveal more – and I’ll post the results then.
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