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Hi @madbean  !

Nothing catastrophic :-) The shopping list is missing R9 (330k)

Cheers
Ben.

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From the Album "Solder and Rust"... Ok that was a bad ozzie joke :-) I'm on a roll this week, here's my Beanscream :-) I went for BJT input buffer because I'm short on JFETs, and I'm happy to get an idea of what the OG sounds like but I can always 'upgrade' later :-)

Cheers !


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It's just me or is PCB hoarding a thing ? :-)

I keep buying "that looks like this might sound good" from Brian (or Aion, occasionally elsewhere)... And end up actually building only a fraction of those.

Sometimes I pick up an old one and bam ! It's been updated ... Then the temptation to buy the updated version....

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Nothing of consequence... Shopping list calls for 2 x 9k1 resistors but there's only one in the B.O.M :-)

Made be check the schematic & Aion's version to be sure I wasn't missing something :-)

@madbean ^

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Tayda delivered, I found some time, here's the next toy for my bassist son !

Only quickly tested on a guitar which I can't really play, it sounds glitchy and all over the place but I think that's the spirit :-) Definitely not meant to play a guitar chord through that thing !



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Hi Folks !

Just wondering if this is just me ... I grabbed a few bags of Nichicon "fine gold" caps from pedalpartsaustralia.com.au (I think stompboxparts has some too), and I've been somewhat struggling with soldering them :-)

I never had that problem before, it's odd... the leg sizes are no bigger than other caps but for some reason they behave like the fat legs of black diodes, ie, it takes a LOT of heating before the solder adheres to the leg. At that point, the cap itself becomes really hot and I already had to replace one that was acting as an open circuit, I suspect due to heat damage.

I normally solder at 380C using lead free solder, I've done it for years, and never had such a problem. I usually don't need to heat a component for more than 1s.

Am I doing something dumb here ? :-)

Here's my Imp build ! I called it YAK (Yet Another Klon). Artwork is good old water slide, before I started playing with Tayda UV. It's an AI generated Centaur with a Yak's head :-)

The mod you can see is a switch doubling the 3n9 tone cap. I should have called it "Fat" rather than T-Boost I suppose....

Ge diodes are D9Es from DIYguitarpedals AU

It sounds great! :-)

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Hi Folks !

So here's the Archibald I made a little while back (and forgot to post about). A few mods in there that might be of interest to folks, and a few "issues" (screwups by me ? :-) in no specific order:

* Took C18 out (between LT1054 pin 1 and ground). I don't know why it's there and Mr Bean either... but in my case it causes the charge pump to fail to start on a cold start 80% of the time, resulting in a rather shitty sounding pedal :-) Pin 1 is "shutdown" when driven to ground. It looks like this cap is big enough to cause my "variant" of LT1054 to see pin 1 asserted before the cap has time to charge and shuts itself down. The cap eventually charges, so a quick power off/on of the circuit kicks it into life. No C18 works best :-)

* I replaced R5 with something much smaller (1k5 off the top of my head). This is closer to some variants of the Tube Driver schematic where that resistor is absent and gives a bit more "clean" range at the beginning of the drive pot. There's some sweet spot there for a mild tube sound which I quite like when I'm not cracking it up fully.

* R18 to V- instead of GND. Otherwise the JFET buffer operates between GND and V+ instead of V- and V+, you lose half your headroom and I've observed it clipping early with the scope, which is not what you want your buffer to do.

* I used a 1590BB2 because Tayda doesn't do BBS and ... it's TIGHT :-) It would be nice if that circuit ever get respun, to have the tube sit one or two mm closer to the face instead of so far down near the lid. I had to "incline" the PCB downards (by taking out the inner nut of the switches and screwing them down further) to avoid having the tube hit the lid. It's unfortunate because it should fit with that one mm extra. If that makes the tube socket too close to the angled connector, then maybe put the connector on the side of the tube rather than below it, a bit like the "wings" that SushiBox/CCE uses ?

* I was dumb and put the jacks & power on my usual spot for a 1590BB2 rather than one the side like the Archibald template suggests. As a result the tip of the output jack almost touches the tip of the tube ... it's very very close. I dodge a bullet here, pfiew !

Otherwise it works and sounds great ! (The little drawing is courtesy of some random online AI :-)


 

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Hi Folks !

So I've finally completeled Skoolie :-) I am not 100% I got it properly calibrated, there are some odd things here, so advice welcome, but otherwise it seems to be doing something not too dissimilar to the E MM demo videos I can see on youtube...

Here's what it looks inside (the wires aren't that neat ... I know). I'll follow up with some of the "issues" I had with calibration (I haven't found how to interleave images and text in the forum)

Hi Folks !

I've posted from time to time for a little while but I realise I never introduced myself ! Let's fix this.

I'm a long time Linux nerd, I used to dabble deep in the kernel (those who ran Linux on their PowerPC Macs might remember) and I work for a Linux distro these days. Electronics is something I am not particularly good at but enjoy nonetheless as a hobby. I'm nuts enough to find soldering somewhat... relaxing !

I build pedals mostly for my bassist kid and his friends ... and because it's fun. I play a bit of keys, but unless I manage to snatch a proper Rhodes one day, I don't particularly see myself hooking a pedal onto my keyboard. Trying to learn the guitar too, but at 50+ it's a slow process

Hi !

While I'm waiting for Tayda to drill, paint and decorate the enclosure, I'm looking at Archibald schematics and wondering about a few things :-)

I would be building this for my son who is primarily a bassist. Now, I couldn't find the schematics/component values out there for the "bass" version of the BK Butler Blue Tube, though I think I found every other variant.

First, I noticed Archibaled has C5 (10n) and R6 (10k)/R7(10k) seemingly forming a high pass filter at the input of V1A with an f3 around 796Hz. Did I miss something ? I feel this would be rather ... detrimental for bass, wouldn't it ? Ideally I clean blend path would be good for low freqs but that's more of a mod than I think I can do easily at this point without doing my own PCB.

That said, I looked at the schematics for the Blue Tube RT-903, and this has in that spot a 47nF cap, and about 110k of resistance to A- (100k + 10k), which would bring f3 to around 30.8Hz. I'm thus thinking of doing that same change. Any particular reason one would think this wouldn't do ? The circuit of the RT-903 is a bit different in that it has 100K before the 10K to A-, then another 10K to the tube grid, meaning 20K from A- to grid. But that also comes with different plate resistors, cathod resistors, etc... ie, all the values differ quite a bit around the tubes themselves.

Any opinion/suggestion before I solder things ? :-)

Another thing I am wondering is how necessary is the regulator circuit when feeding the pedal 12V ? Can't we just wire 12V more/less directly into the tube heaters in series ? This seems to be the go-to option for a number of other tube designs I've seen around (including feeding them a meek 9V)

Thanks !

Cheers,
Ben.

Hi !

I'm building the "clean" variant with C11, C12 and C16 replaced with 220nF for use with a bass (suggestion by TH).

I wonder how to adjust the trim pots. Is there a specific bias voltage to look for ? Or I just tweak them until I like the sound ?

Thanks !

Hi folks !

I hope somebody can be a assistance, otherwise I'll continue digging...

So I'm waiting for my Flunkee PCBs (a friend in the US ordered them for me and will get them to me, but it will take a while) so in the meantime I put it all together on a breadboard to play around with the kind of mods that can be done etc...

However, I have so far failed to get it going, and while I'm generally "ok" at debugging simpler circuits, I don't fully understand (yet) the 13700..

(Note: I've started from the dod schematics one can find around and switched to the Flunkee ones eventually, but I'm still using the two halves of the lm13700 the way the original dod does, though I don't think that matters).

There are my observations so far, any hint would be appreciated:

- First the bias voltage (VB) drops to a bit above 3V (ie, if I unplug the supply, the resistor bridge r23/r24 provides 4.5V but it looks like the various other resistors on that net will pull it further down). I assume it's normal but I'm asking nonetheless :-) (mostly I suspect via R8 -> R12 -> R18 which totals 45K extra path to ground)

- I've fed it with a sine wave from a generator (1KHz,  +/- 800mV). I can see the first part of the LM1458 (the buffer) output it just fine. The second LM1458 amplifies it. Past C5 (on the neg leg, or between the two diodes) I observe half sine waves with a roughly 4 to 6V amplitude depending on the SENSE pot, so far so good. C5 and R6 flatten and bias this, generating a VR envelope of about 3V to 4.5V (depending on SENSE) when a sound is played to a bit above 1V when not. So far it looks like somewhat reasonable but remember I don't fully understand the circuit :-)

- Where things get less clear is the other path out of the first 1458, via C6 and R7 to the + input of the first  half of the 13700 (in my case I use the first half like the original fx25, Flunkee use the second but my undertanding is that they are identical). I can see my signal the output of C6, however still biased positively by about 2.9V. I assume this is R7+R9 doing that. *However* if I probe past R7, ie, on the + input of the LM13700 (pin 3 in my case) the signal is a LOT flatter. IE, I see something that vaguely oscillate around the 2.9V bias voltage but it's only 200 to 300mV peak to peak. Pin 4 (the - input) gets between 2.7 and 2.8V (depends on envelope), and pin 5 is flat outputing about 7.8V. Nothing that look like a signal at that point. Pin 1 (coming from the envelope circuit) is at about 1.2..1.3V (depends on SENSE).

Now I tried 2 different LM13700, I've verified their V+ (9V) and V- (0V) on pins 11 and 6 respectively, etc... I basically get no signal past the first LM13700 stage.

Any idea what I might have got wrong here ? :-)

Cheers,
Ben.