freestompboxes.org

Cub wrote: ↑11 Jan 2023, 11:54 Though I have to admit, I'm starting to reach that age where it's getting harder to tell colours apart. Therefore, I attached them so younger eyes can have a look as well.

I think age on these forums (as well as in real life) absolutely doesn't matter -- except perhaps regarding color recognition
BUT the problem here is not our eyes, but the shifted color temperature of the pictures..
which makes some colors hard to recognize... sometimes

Anyway,
I've gone through Kasper's pictures, reading the color codes...
and in the end they are (seem to be) in total match with those in Val's shots

I was obviously shooting with a canon at a sparrow,
I meticulously went through VAL's shots reading the color codes.
only to realize in the end that although some resistors had managed to elude the camera,
they were the same as in KASPER's shots (!), <-- success for me, but it really was superfluous

Wow jeepe, you really put your back into it ! It's so awesome that after all these years, this fine sounding box of dirt is finally giving up its secrets.

Cub wrote: ↑21 Jan 2023, 21:54 Wow jeepe, you really put your back into it ! It's so awesome that after all these years, this fine sounding box of dirt is finally giving up its secrets.

I was only reading the color codes, this is just a check, just a subtle layer over the HUGE work that Kasper carried out...

mirosol wrote: ↑02 Jan 2023, 18:13 Nice work on the schem!

However. Are you sure about the way the boost switch is wired? In that position, when activated it takes the 2k2 in parallel with gain pot + the 150R. And that would mean the ohm value on feedBack loop would be set at something like 2K1 even with 47K pot maxed.

Otherwise this looks good. Well drawn, easy to read etc.
+m

This question with the gain pot and the extra gain resistor was really annoying me, too...
although I'm really new in electronics, it seemed illogical...
until I visited Electrosmash's rat analysis page...
where they say:


Gvmax = 1 + 100K / 47||560 = 2305 (67dB)

I didn't understand it then I looked up the meaning of double slash : equivalent resistor value of two parallel resistors
(I'm saying it for everybody's sake, not yours, Mirosol )

this, BTW assumes a parenthesis...
so, it actually reads like: Gvmax = 1 + (100K / (47||560)) = 2305 (67dB)
43//560 = 43,36
now we can see how that "2305" came out // it is actually 2306... and we should also add +1...

---

What we know is that without the boost ON, the (voltage) gain is at 15dB
and we also know that the RAT can yield 67dB (voltage) gain...

so, 100K resistance gives us 67dB gain
then, how much gain do we get using 47K ??
I thought (stupidly, but it's normal) it would be 33dB ....
but no! logarithmic calculations don't work like linear ones (as it seems), and gain in dB is logarithmic

47K will yield around 60dB ... (check the calculator, voltage gain)

now, let's see, how much is 15dB gain!
I'm sure that many of you know it, even for me this wasn't the first time converting gain number to dB...
but I was surprised to see that 15dB only means gain around 6..., like 6x -- "6 times"

so, we could think that the small feedback resistance (ca. 2.1k) would produce this...
and the case would be solved

however,
the electrosmash calculation of gain goes like this:

when we
instead of 47000 / (47//560)...
i.e.: instead of 47000 / 43.36 (which would be ca. 1080x gain -> ca. 60db)
take 2100 / 43.36, it will produce NOT "6x", but 48x gain... which is 33.dB gain NOT 15 dB...

But the Mudhoney produces 15dB gain when the boost is limited by that switch...
So... something is still not clear yet

doing the math "we can solve this equation"

BUT I might be wrong, especially because I'm only playing with numbers and formulas I know nothing of...


anyway,
the gain we look for is 6x (6 times), and that comes out as
1+ (Feedback resistance / 43.36) = 6

that is:
5= Feedback resistance / 43.36
so, Feedback resistance = 216 ohms

OR, let's not forget that the maximum 15dB boost is achieved by the whole box! which can have attenuation,
I mean, the opamp might do 48x amplification while the box will only produce 6x altogether (this is just a tipp)

and please don't trust me!!! I've been only playing with numbers and formulas I know nothing of...

That switch is a very clever trick and I've decided that for my forthcoming Rat clone, I'm not going to experiment with values for a Ruetz-like mod. In the past, I ended up setting the pot where it sounded good and never touching it again. It was close to the stock value anyway. Experimenting with multiple filters on a switch has led me to go for the slightly tweaked stock sound and completely ignore the other side of the switch after the first couple of times playing with it.

Instead, I'm going to Frankenstein a dual pot together with 100k log and 50k log wafers. With the parallel 2.2k resistor and an on/on/on switch, I can get all the gain ranges of the Rat, the boosted Mud and the Mud in regular mode. All with the original tapers intact.

Add another switch with two or possibly three sets of clippers and it'll be the ultimate Rat !

Kasperrosenlund wrote: ↑11 Jan 2023, 16:45

Cub wrote: ↑05 Jan 2023, 20:06 Found the "Valentinych" site: http://valentinych.ru/o-zvuke/gitarnye- ... rmy-t-rex/
I noticed a few differences between Kasper's and Val's schematics,
but I can't see a version number on the boards on Val's site.

Code: Select all

 Kasper   │ Val
──────────┼──────────
 R1  470r │ Rb1  100r
 R2   10k │ Rb2  6.8k
 R3   10k │ Rb3  6.8k
 R10 100k │ missing  
 R11 150r │ Ra9   15k
 R20 510k │ Ra17 100k
 R22 100r │ Ra19 1.5k
 missing  │ Ra20  10k
C16 100nF │ Ca14 10nF
D5 1N4007 │ missing  

Thanks!
I will recheck mine and see if I missed something.
One thing I now know that is missing in my trace is the 10k at the output - that is in mine as well, apparently just forgot it in the schematic.

I will look into it one of the next couple of days.

Okay yea admitted..... it took quite a bit longer to get to it - you know how life can keep you busy. But I just went back into my Mudhoney and compared. I also dug up my hand drawn trace, and I can see that I made a typo in my schematic.
Of all the differences listed by Cub, my schematic is correctly reflecting my pedal - EXCEPT for R1, which should be 47R not 470R (typo) and the missing 10k at the output (Ra20 in Vals schematic). I will update the schematic tonight and repost it.
Mirosol, you might want to update your stripboard layout as well .

jeepe wrote: ↑21 Jan 2023, 23:58 This question with the gain pot and the extra gain resistor was really annoying me, too...
although I'm really new in electronics, it seemed illogical...
until I visited Electrosmash's rat analysis page...
[etc.]...

Wow, you really dug into this! I will not act as if I understand all the math, but it seems to make sense

Cub wrote: ↑27 Jan 2023, 08:30 That switch is a very clever trick and I've decided that for my forthcoming Rat clone [...]

Nice, keep us updated!

Here it is...

Revised schematic:



As mentioned the changes are the value of R1 and the forgotten R28 - they are also made bold in the revision.

/K

Kasperrosenlund wrote: ↑13 Feb 2023, 11:09

Cub wrote: ↑27 Jan 2023, 08:30 That switch is a very clever trick and I've decided that for my forthcoming Rat clone [...]

Nice, keep us updated!

Will do ! It might be a while before I can get to it, but it will be awesome. For a large part thanks to your work, now that the mystery of that fine sounding Danish Dirtbox is finally solved.

Kasperrosenlund wrote: ↑14 Feb 2023, 16:08 Here it is...

Revised schematic:

As mentioned the changes are the value of R1 and the forgotten R28 - they are also made bold in the revision.

/K

hi!

now it's truly amazing! great work!
Great contribution!!! THANK YOU, Kasper!!

the vero layout need be updated still...
confusingly it has the version number v1.1. too...
so someone could mistakenly think that it has been updated with these 2 changes...

PS:
I've already created the vero board but haven't planted anything in it yet,
so it was easy to update it -- 2 cuts only...
I just attach it, it might save someone 5 minutes

EDIT:
image removed, because of errors and being superfluous

Guess i may be in need for more schooling, not sure. However. The V1.1 is per description on my original post on the blog https://tagboardeffects.blogspot.com/20 ... y-v11.html

I recall reading how most of the Mudhoney DIY builds were just not sounding right.. Recently re-traced on FSB by Kasper, from his V1.1 version of the pedal - there may have been a fault with the schematics that previously floated around the web. When i saw this, i thought "the switch shouldn't work like that".. But it seems like it really does, and with this configuration, instead of the Ruetz-style mods on the Rat, one may finally get that Mudhoney (err.. tuned Rat?) tone out from a stripboard. There are the BJT transistor buffers in place to keep the topology close to an idol, but obviously the electronic switching is removed to accomodate true bypass. The oldee PSG demo may look outdated today, but it does not sound bad. And hey! It starts with a Dinosaur Jr riff with the pedal!

So that 1.1 points to revision marking on Kasper's pedal and has not much to do with the layout.

Anyway. 47r as current limiter for supply and the 10k output pulldown won't affect thefunction or the tone all that much. But yeah, the layout is incorrect. Surely, still a lot closer than the previous ones over the past 10 years. However. The "mods" posted above (with my name still in tact and no mention where these mods came from) has an error in it. The 10k should be shunt to ground as a pulldown and not placed in series with the output.

Previous version of the layout works also. And from what i've heard, it sounds as it should.

mirosol wrote: ↑27 Feb 2023, 18:35 Guess i may be in need for more schooling, not sure. However. The V1.1 is per description on my original post on the blog https://tagboardeffects.blogspot.com/20 ... y-v11.html

So that 1.1 points to revision marking on Kasper's pedal and has not much to do with the layout.

Anyway. 47r as current limiter for supply and the 10k output pulldown won't affect thefunction or the tone all that much. But yeah, the layout is incorrect. Surely, still a lot closer than the previous ones over the past 10 years. However. The "mods" posted above (with my name still in tact and no mention where these mods came from) has an error in it. The 10k should be shunt to ground as a pulldown and not placed in series with the output.

Previous version of the layout works also. And from what i've heard, it sounds as it should.

hi, Mirosol,
I didn't mean to blame you whatsoever!
I was also absolutely aware that your version 1.1 meant the development of your layout, not that of the circuit...
I pointed this out as a possible cause for a misinterpretation...

Sorry also for using your layout as I did...
I wouldn't put my name on it cause I had nothing to do with it...
I didn't realize that that could make it appear as if you had made those cosmetic changes to it..

I apologize!

and thank you for warning (everybody) about the error I made... (so stupid)
with that you also saved my build, thank you!

PS:
I was making this "sketchy" version for myself in GIMP...
It was just a sudden idea to upload it -- a stupid one, now I realize, I should have only done this after having finished and verified it)

Well. We're all friends here.
To go back to ye oldee post, i was merely wondering/being baffled about the control range on switch positions. I'm not saying i'm sorry for being wrong. Range of around 1-3K vs. 1-50k. Yeah, there is gain on both. But to assume those are usable, that's another thing.

You could have put in a mention that the mods were yours.

I think there's a nice old clip of Benny Hill out there.https://www.youtube.com/watch?v=bPsg42EKJic
And to make things even more complicated. I think we should not make any assumptions on behalf of anyone but ourselves.

Edit. Could have been more mature about stuff. Result of a long, bad day. This above isn't exactly up to my standards for communicating. So, i aplogise too.

+m

Just a little addition:
I've now built a clone on strip board following mirosols corrected layout and compared it to my original unit - and it sounds and feels completely the same. Succes!

/K