DC 2 Dimension C build question

[Morocotopo]

Hello virtual space fellows, here I am finishing my B*ss DC 2 Dimension C, made with the Topopiccione layout and info:

http://topopiccione.atspace.com/PJ18BossDC2.html

It´s working good, it was HELL to solder, close to 200 parts... I´m half blind right now...
Anyway, I have some doubts about the connection of C59/C60/C62, and the mono/stereo switch. It´s not clear (at least to me) how to wire these parts from the layout, and looking at the schem, since there is a FET in the original (Q3) that´s removed on the layout, that doesn´t help either. Anyone can help with this part?

Also, I´m planning to use this bypass switch schem:

http://www.diystompboxes.com/smfforum/index.php?topic=54067.0

BUT, since this is a true bypass switching configuration, if I have the thing connected to two amps or whatever, in bypass I would be loading down the guitar signal too much, so I thought to add an IC buffer at the input (switchable), so that in bypass I will have a buffered signal driving the two outputs. What do you think about this solution?

Thanks for any help

Morocotopo

[Morocotopo]

A little soundfile:

http://www.aronnelson.com/gallery/main.php/v/Morocotopo/DC+2+test+-+humbuckers.mp3.html

[DougH]

Re. the bypass scheme- You will have 2 amps in parallel, so let's say for argument they are typical tube amps with 1M grid to ground resistors on the inputs. The Zin will essentially be 1M for each amp, so with the 2 in parallel you end up with Zin of 500k. That's not going to be significant IMO. It won't load the pickup noticeably. If the amp has an input coupling cap you could possibly notice a loss of bass if the cap is small enough- but that's not typical. I would suggest doing an A/B comparison - turn one of the amps down and check the bypass sound through your DC 2 into one amp using your bypass scheme. Then plug the guitar directly into the amp and compare. If you don't notice a difference, don't worry about it. Otherwise yes, the bypass buffer would be a good idea, as long as you don't mind having a buffer in your chain.

Your sound clip sounds great! Nice playing too.

Here's a clip of one of my amps with my Boss PS-5 detune function:

http://www.aronnelson.com/gallery/main.php/v/DougH/amp/chime/ChimeDetuneMix.mp3.html (It's just a mono clip.)

I've traced through the Boss product line trying to figure out what happened to the DC-2, and I believe it ended up implemented as an algorithm in the PS-5 detune function. It does basically the same thing although being DSP I'm sure it sounds different.

I have a Behringer CC300 (DC-2 clone) on its way, was shipped yesterday. I think it would be fun to compare/contrast some of the different "motionless choruses" to ea other. I think it is a great effect, esp in stereo.

[lowstar]

i finished this some time ago, and i wondered about the mono/stereo section as well, i had a thread where i particularly discussed my findings, but nobody seemed interested. a friend of mine has a real one, and i borrowed it and checked and it seems true what i thought.
i can´t quite remember anymore the exact things because there have been literally 40 or more boxes in between, as well as countless gigs and a real life with a daytime job to master. 
but here´s the link to my musings: http://www.diystompboxes.com/smfforum/index.php?topic=54547.0

after i compared my build to the real thing i realised that the light clipping with hard notes and hot pickups is inherent in the original, too (i was trying to find a mistake i had not made...trying lower gain transistors and so on).

i´m interested what you think of my findings with the stereo/mono switch.

cheers,
lowstar

[Morocotopo]

Doug, thanks for the answer, I included a buffer anyway (switchable) so that I can use the thing as a splitter in any situation, even if I don´t have the FX on (bonus function!). When you get the Behringer, tell us how it sounds and/or make us some sound clips, so that we can compare units!

Lowstar, I ended up connecting it in the way you describe in your thread. Exact same findings. Connected as per the layout it worked anyway, but I suspect not to its full potential.  I guess there´s a mistake in the layout. I think it would have been wiser to keep the part of the schem that switches from mono to stereo in the layout, it´s only a FET and a few other parts. But hey, you can add it in a little board anyway. one thing that surprises me is that there´s no ticking at all, even without shielded wires and with no enclosure! I wasn´t that confident in that regard, seeing all the jumpers and wires that the layout has...

By the way, I have yet to hear clipping... haven´t done a thorough listening test yet, though...

One thing I did was to clean up the schem according to the Topopiccione layout, eliminated all the parts not used, here it is, in case it´s useful for someone (I think it´s correct, but check it anyway just in case I missed something):

[DougH]

When you get the Behringer, tell us how it sounds and/or make us some sound clips, so that we can compare units!

Here's my initial impression of it: http://www.diystompboxes.com/smfforum/index.php?topic=72707.0 

I haven't had much of a chance to play with it since the other night.

[lowstar]

hey morocotopo,

great, finally somebody else looked at the matter and found the same things.
yeah, one thing preventing me from putting the sucker in a box is that i´m not sure about the bypass i should use - with this kind of effect (also because of the stereo issue) i´m also tempted to re-use the fet switching from the original, but i have not looked into the matter yet.
maybe we should come up with a small daughterboard to allow for the fet switching.

cheers,
lowstar

[jfromel]

In the DC-2 clone that I build, I am using a millinium type LED with true bypass stereo switching on the 3PDT. It works great. My layout is a little tighter than toppicone's and does not have any jumpers because it's double sided. Anyhow I toyed with the idea of a buffer and ultimately decided against it becuase the sound was fine without. Regarding the headroom and clipping, try usiing the following op-amps - OPA2134 for the input and output, TL072 for the BBD, and TL062 for the LFO. That should help as well as putting in higher rated caps than spec'd on the schem. I can hit mine with an incredible amount of gain before clipping.

Hope this helps.

I think I still have some DIY boards based on the Dim-C but it has some extras added such as stereo input and expanded lfo.

[lowstar]

it´s been awhile since the last post in this thread, but i started to tinker around with this circuit again.
i tried the suggested changes of the ic´s, i could not hear a difference with the opa2134´s though that would justify the use of those expensive chips in there...maybe when it is boxed up. but, i put the tl062 in the lfo and swapped the other 4558´s with tl072.

but, to the bypass question: since this effect is going to be used only in mono mode for live operation anyway, and stereo only in the studio, i wondered, why not use a normal 3pdt config for the mono operation, and have the stereo out non-switchable (i mean from clean to effected) ? what do you guys think about it ?
a real stereo bypass switching scheme could always be added later if the need should arise, but for now, at last it would go into it´s long deserved housing (after more than one year i think)...

cheers,
lowstar

[lowstar]

when i boxed up my dc-2 recently, i was doing some more listening tests and heard this background noise that is in rhythm with the clock. i got an original to compare, and sure enough, that one is much more silent.
i went over the build countless times, checked and rechecked everything, to no avail.
now, i came back to this post, and listened to morocotopo´s soundfile...bam, there it is ! he has the same noise. when you play fast lines, it´s not as noticeable, but when you strike somthing like a flageolet chord, or just let notes ring longer, there is this noise in the background, going shh-shh-shh, with some occasional clicks or pops (very faint, but it is there). i can hear it in his soundfile, even with the fast playing (you gotta use earphones or good speakers tho).
so the longer i´ve been fiddling with this, the more i think it is the layout.
some traces extend over half the pcb, that are kept closer together on the original. plus, all the jumpers...somewhere, the booboo happens.
i´ve also already shielded the cables going to the rate pot, but that is not the culprit.
but i can´t shield every blood jumper on the board ! and then again it might come from one of the traces itself, so shielding the jumpers might be useless.
bummer ! otherwise, it´s sounding brilliant.

morocotopo, when you read this, could you check your build again ? play a chord, let it ring and see what happens. if you have trouble hearing the noise, pull ic12 from the board and try again...now you hear mostly just the two delay lines with no bass boost, it is more prominent that way.

cheers,
lowstar