analogguru wrote:
470k is correct. You forget, that the bias divider is connected directly to the non-inverting input, resulting in a total max. input impedance of only 150k. (47k would give a max. input impedance of < 20k). BTW, I think R2 should be 2M7.
analogguru
sorry.. didn't look at the schematic.. just assumed it was like the others.
culturejam wrote: We are equal opportunity exposure artists.
Not trying to diminish any work done on this project but does any one else have the idea that the C1 is really 47n? The clips don't really wow me on this one but I would really like to see a Sweet Honey dissected..
ibodog2 wrote:
I don't think I understand your graphs. Could you explain what they are showing?
These were done using LTSpice and should show the interaction between the Z pot and the pickups (if the software is calculating everything correctly).
http://i42.tinypic.com/11vsivn.png
This one shows the input impedance as measured at the input of the circuit. voltage / current = resistance
http://i43.tinypic.com/6599oz.png
Here is the same circuit but with an addition of a pickup simulation with a 1H inductor and 250k tone and volume pots on maximum. I measured voltage at the input of the sbod section and current across the inductor, so this should theoretically show how the Z control interacts directly with the pickup i.e. the wire going out of the pickup, before the tone and volume pots on the guitar.
http://i39.tinypic.com/2qx3urc.png
This is what the opamp sees at it's input as the Z pot goes from 0.5k to 500k. I used pickup simulation here as well.
ibodog2 wrote:
In my experience playing guitar and doing recordings most guitar players now like guitar tones that have too much bass. It sounds great standing in front of the amp playing by itself. But doesn't fit well when playing in the context of a group.
I agree.
A pedal that works well in a band situation will often be bordering on sounding a bit harsh on it's own.
And there you walk the fine line between the players who jam at home with.. mainly themselves, and the working musicians.
I suspect most the cork sniffers are home players.
culturejam wrote: We are equal opportunity exposure artists.
TheLemon wrote:Not trying to diminish any work done on this project but does any one else have the idea that the C1 is really 47n?
I thought it would be 100n. But I removed the cap and measured it at 4.7n and I can see the reverse imprint of the value from the side of the cap rubbed off on the goop. It looks roughly like 4700 100- exactly like another Wima cap I have.
You are correct Sir! I have one from a newer batch, sans goop, and I can clearly read "WIMA 4700 100-".
Though some of the lettering (printed on the tops) on three of my caps have been melted with a soldering iron.
I'll never understand the "secrecy" ... no one has ever built an overdrive pedal.
"Political correctness is a doctrine, fostered by a delusional, illogical minority, and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a turd by the clean end."
I just received a half dozen OP275's, and so far the differences are fairly noticeable in most of the pedals that I've tried them in. Not always better, but the point of the SBO being tuned around it seems to make sense.
measuring resistance "in-circuit" is risky business, because it essentially puts the rest of the circuit in parallel with the R you are trying to measure.
Black Dynamite wrote:you need to shut the fuck up when grown folks is talkin.
Sorry, I meant to say "minor volume and/or tone discrepancies". If a Pot is supposed to be 100k and is only ~80k, we could be losing some range of SOMETHING if its used as a variable resistor. But even that would be a very minor effect, probably only heard if comparing two pedals side by side, which is why I suggested it. I wasn't sure how much discrepancy you were describing.
Black Dynamite wrote:you need to shut the fuck up when grown folks is talkin.
Velcome all! Ibodog2, thank you for excellent job! If shematic is right, not neсessary to use dual gang TEXTURE pot, take a single B1K , connect "2"to GROUND, "1"to FETs, "3"to C7. That’s ALL! With BA4558 SBOD sounds great, better than KOT, CrunchBox (IMO).
Sorry for bad ENGLISH from East Europe. Good luck to ALL!
ibodog2 wrote:Well, in this case my memory was serving me wrong. My vero build sounds exactly like the original I traced and put back together last night!
My build sounds just the same too, but doesn't need a dual "Texture" control:
It's not a bad version of the usual, and the FETs can be usefully changed for other clipping devices if you want differing sounds. I increased the Texture control to 5k for more useful range.
"Why is it humming?" "Because it doesn't know the words!"
thanks a lot for the tracing and the vero layout! I just build it and I like it, but I definitley think it needs more presence or a little bit more treble... hmm, decreasing C3 would be too simple, or what do you think?
sorry.. didn't look at the schematic.. just assumed it was like the others.
