Looking for a Schematic: Danelectro Chorus (DJ7/Rumor)

[somnif]

Hey folks, I am on a hunt to try and replicate a bit of aural nostalgia.

Back in high school, I got my first bass guitar, a Danelectro "Rumor". Cheap and chearful, with an interesting built-in chorus function. Not a bad instrument for under 250$.

I have been curious for a while what sort of circuit they used in the beast, and knowing dano, I assume they went as cheap as possible and used a similar (or even identical) circuit to their mini pedal, the DJ7 "Milkshake". Unfortunately its one pedal I can't find a schem for. Not even any clear gutshots to puzzle over. (And annoyingly the Bass is sitting in my dads place several hundred miles away).

A bit of a long shot, but does anyone know what sort of architecture they used for it? I can't imagine them using BBDs in a sub-50$ pedal in 2003, but I'd love to know either way. Its been bugging me for a while, and I thought I'd ask around.

This is the only gut shot I could find: http://mirosol.kapsi.fi/wp-content/uploads/2013/08/DJ7-Milkshake-guts.jpg Typical dano soldering, and probably another board/components on the other side. Other than the 4013, its too blurry for me to make out whats on the chips

Any ideas?

[reddesert]

Yer in luck, I have a Danelectro Milkshake right here. It actually has two PCBs inside, which I think is true of most or all of the Dano mini pedals. 

The picture on Mirosol's website is of the "upper" PCB when you remove the baseplate, ie lower PCB when in the operating position.  The ICs on this pcb are labeled TL072C, HEF4063BT or 4053?, and U324 4013 (14 pin) - so that's a dual op-amp; probably a CMOS chip; and either a quad op-amp or more likely a CMOS flip-flop.  The CMOS chip(s) are presumably for switching. The other side of this board has the jacks, but no traces.

The lower board is the heart of the matter. This has another TL072C and a large SMD IC labeled CD2398S with 28 pins. I will bet a milkshake (actually several milkshakes) that this is a version of the PT2398 echo chip, obviously a relative of the PT2399. The PT2398 datasheet I found has almost no specs, but supposedly it can do shorter delays than the PT2399, which might make sense in this application.

[somnif]

Ok, I was almost sure it was going to be a pt2399 chorus (they used one in their god awful "reverb" mini pedal, the corned beef) but a 2398, that is interesting. i know they used a pt2395 in one of their delays, so I suppose it makes sense they'd branch out a bit.

But thanks! I appreciate it. I have a ton of dano stuff (got a 6 pack of the mini pedals for 20$ back in like 2004, the milkshake wasn't one of them) and I've always been sort of fond for their lousyness. Its like an ugly, three legged, blind dog. Kinda useless, fairly offensive to several senses, but you can't help but smile at the thing.

edit: Never mind, just realized the Fab chorus has a "mix" pot the DJ7 lacked, so not an identical circuit. Probably similar though)

[matmosphere]

Didn't they make a good Foxx Tone Machine clone that cost twenty bucks or so? I think the tremolo was supposed to be decent too.

[somnif]

Didn't they make a good Foxx Tone Machine clone that cost twenty bucks or so? I think the tremolo was supposed to be decent too.

The French Toast Octave fuzz, my very first ever effects pedal (Mostly because yeah, it was 20$). A short while later I got this collection (~2003-ish) for less than 30$ (cant recall if it was 20 or 25, but something like that) so I ended up with a second french toast as well.



2 of the pedals had iffy solder joints leading to effect cut outs, the phaser (a jfet design) was no where near biased, and the compressor has so much noise I have actually used it as a signal generator for testing purposes before.

Its hilarious.

[Betty Wont]

I really dug the Black Licorice from this line. It was a metal distortion with an octave down that tracked really well, much better than a Blue Box. But the previously stated switching and DOA issues made that a dead end. I'd like to know what was going on in there. In fact i got into pedal building trying to repair the junk.

[somnif]

So now knowing that it has a 2398 in its guts, I wonder if its the same circuit as their newer "Fab" chorus. It too uses a 2398.

I'm still trying to hunt down what (if anything) they borrowed the circuit design from. With many pedals of theirs its quite easy, but this is an odd one. The later model Boss CH-1 chorus used a ES56028, for which the 2398 is apparently a drop in replacement (or so says the datasheet). However the CH-1 was a much more robust circuit than the dano block, so I'm thinking that is correlation rather than causation.

The hunt continues! (For all I know its something like a karaoke machine circuit they borrowed, wouldn't surprise me)

[reddesert]

The Chicken Salad vibe from that mini pedal series sounds pretty good. I got the Milkshake chorus along with it in a single ebay auction for the pair. The Milkshake sounds okay to me - since I had it out, I plugged in the bass and played the two Joy Division bass riffs that I know ... 

I didn't know that Dano made a bass with built in chorus. I wasn't paying much attention to music gear in the 90s-00s when these came out. Never realized just how cheesy the knob attachment is on these pedals. I took some gutshots while the pedal was open and could post them on freestompboxes. It could be traced since it's mostly SMD and the traces are only on one side.

[somnif]

Yep! The "Rumor" bass came out in 2001 (I think, ive or take a year). Pretty standard budget P-bass clone. Volume and tone knobs, with a built in chorus (no control beyond on/off).

http://guitarsandaudio.com/extras/13GASpics/Misc/01Danobass/01Danobass.JPG

I liked the blue burst color (though the glitter was a bit much). The body has a nice mass too it, and the neck is at least straight enough. The fret work on mine was pretty cheap, though. Probably could have been mitigated with a better set up, but even with the action jacked way up I still got some buzz (was a hell of a finger workout playing with a 1/8" of play to the strings though!).

Also interesting in that it had separate output jacks depending on whether or not you wanted to use the chorus. It had a straight output, and an effect output (which switched the onboard 9v batter on). Did allow for stereo use though, which was a cool little toy to play with.

But I loved the stupid thing, because it was mine (and that matters a lot when you're 16).

I'd love to see some gutshots of the DJ7 if you can link to them. From what I've been reading, It looks like some 2398 "chorus" circuits are based around the chips "surround sound" emulation function. I'm curious to see how dano did it.

[reddesert]

I made a thread for it on freestompboxes and posted the pictures there. http://freestompboxes.org/viewtopic.php?f=1&t=28448

[somnif]

I made a thread for it on freestompboxes and posted the pictures there. http://freestompboxes.org/viewtopic.php?f=1&t=28448

Thanks! And man that just confuses me further! Either the pinout is different than a pt2398, or its using a wildly different circuit than the applications in the datasheet. Neat!