"A box later" Dumble

[rccolgan]

oh my goodness I'm about to faint

[Guy77]

Thank you for posting Ayan!
Maybe we can use LND150's for this circuit.

G.

[rccolgan]

Thank you for posting Ayan!
Maybe we can use LND150's for this circuit.

G.

I believe the lnd150 version has been accomplished by TTown and in other places

https://el34world.com/Forum/index.php?topic=13857.0


We can assume and build a very dense bi polar power supply, so effort towards the main signal board should be first.

I see the pot is a B2k? Hard to tell with the film caps at this low resolution. Any idea which electronics book he could have borrowed inspiration from like his FET circuit? I assume his bread and butter was tube amps and not refining op amp circuits

[rootz]

Yes, a 2k drive pot Ryan! And a big axial electrolytic cap going to it. Guess this amp hasn't got any of that infamous high end shaving the D'lator has.
I also see no output volume pot. Looks like the other pot is directly from the effects return, so a recovery input pot.
There's a ceramic on the opamp board. Might be on the feedback path? Looks like there is also a small blue tant cap there?
The trimmers on the PS pcb's are a dead giveaway they are something like lm317/337.

[GPD]

Interesting...

Gil, thanks for sharing. Obviously an Op-Amp variation on the Mono Dumbleator...

The enclosure looks like something straight out of an old LM/Heeger catalog or perhaps Hammond from the 1980's. That color I've seen before on standard catalog vendor enclosures...Hammond for certain had that color as an option.

Obviously, this is Op-Amp based so either +12V/-12V or maybe +15V/-15V...impossible to tell without more detailed pix. LM-741 or LM-324 were very popular in the late 1970's into the 1980's...could be one of those or any number of others.

I would say the power supply (The two discrete boards with the VR's, look closely at the polarity of the lytics, they are opposite of one another) meaning one is +12V and the other is -12V...so total of 24V with Ground as the reference. Dumble did this to get the required swing.

Looks like a very basic Op-Amp circuit.

Without ever hearing this loop pedal in action...I can already tell the noise floor isn't going to be not so great...never a good idea to mount the tranny in close proximity to those boards. The aluminum enclosure helps a bit as does the shielded wire but I'll bet there is audible hum from this pedal.

No way to get around it without a custom Mu Metal enclosure for that tranny.

[rccolgan]

(thanks again, @ayan!!)

I agree this is likely a very simple op amp circuit. The LM741 does seem to fit the bill of the era too.

I'm happy to sponsor and make available the boards in open source format if that helps motivation here.

As for the initial power supply, Aion Electronics has a neat +/- 15vdc power supply that runs off a standard 9vdc pedal supply.

[rccolgan]

Best I could do altering the 640x480 images shot on the Sony Cybershot camera metadata says 2003 so it's possible that's the best resolution that might be available... I hope not tho!

[rccolgan]

Got a lot of "Popular Electronics" to read thru from the 60s & 70s

https://deramp.com/swtpc.com/PopularElectronics/

Also looking up Barcus Berry schematics but I don't think I've come across anything good so far. That 2k pot is throwing me off as a usable level pot. Lowest I've seen is 10k in that spot. Funny enough, that is with the Vemuram TSV808 clone I did.

[dbharris]

Are we sure these were built so early in the timeline? Maybe more like a 90s to 2000s thing? Is that story that HAD would build this for John Mayer or would only sell this to him?

With those box film caps and radials it may not be so early.

I would guess the two large box caps are input and output coupling caps large enough to not cutoff any of the useable frequency range.

Check out the Marshall JCM 900 schematic I've attached...

-Dan

[rccolgan]

I don't believe Dumble ever sold anything to Mayer. I recall interviews of associates of Dumble alluding that Dumble strongly disliked Mayer and his misogynistic ways (guitar wanker interview, I think). https://www.guitarwank.com/podcast/epis ... -15th-2022

The story is Josh @ JHS cloned (or built something inspired by) the "a box later" and called "Box it later" in a smaller footprint. Naturally, this is my entry point to learning more about this little device. I did reach out to Josh but nothing substantial in his reply to assist here.

[WhopperPlate]

Are we sure these were built so early in the timeline? Maybe more like a 90s to 2000s thing?

Betcha $ on this

[rccolgan]

Are we sure these were built so early in the timeline? Maybe more like a 90s to 2000s thing?

Betcha $ on this

I've warmed up to this. Good stuff. Makes possibilities a lot more endless now lol

@Dan thanks for the JCM schematic. A dual op amp seems most likely too in the single 8 pin IC.

[dbharris]

Are we sure these were built so early in the timeline? Maybe more like a 90s to 2000s thing?

Betcha $ on this

My only interest is in figuring out what's accurate

What year do you think this was built (and why?)

-Dan

[dbharris]

I don't believe Dumble ever sold anything to Mayer. I recall interviews of associates of Dumble alluding that Dumble strongly disliked Mayer and his misogynistic ways (guitar wanker interview, I think). https://www.guitarwank.com/podcast/epis ... -15th-2022

The story is Josh @ JHS cloned (or built something inspired by) the "a box later" and called "Box it later" in a smaller footprint. Naturally, this is my entry point to learning more about this little device. I did reach out to Josh but nothing substantial in his reply to assist here.

OK, I must be misremembering how JM acquired this piece. I thought HAD blacklisted him after JM let the two rock guys inside SSS 002 and they cloned it as the Oak Cliff Special. But I imagine it could be for all of the above...

-Dan

[rccolgan]

I don't believe Dumble ever sold anything to Mayer. I recall interviews of associates of Dumble alluding that Dumble strongly disliked Mayer and his misogynistic ways (guitar wanker interview, I think). https://www.guitarwank.com/podcast/epis ... -15th-2022

The story is Josh @ JHS cloned (or built something inspired by) the "a box later" and called "Box it later" in a smaller footprint. Naturally, this is my entry point to learning more about this little device. I did reach out to Josh but nothing substantial in his reply to assist here.

OK, I must be misremembering how JM acquired this piece. I thought HAD blacklisted him after JM let the two rock guys inside SSS 002 and they cloned it as the Oak Cliff Special. But I imagine it could be for all of the above...

-Dan

Lol I forgot that one too!

I agree, I'm curious how accurate we can get! I think I hit a wall of accuracy tho