Tuesday, September 4, 2018
Ramble FX Marvel Drive 2/3
Here's a newer version of the Marvel Drive from Ramble FX. Did the first version of this circuit a couple years ago, and decided to update the layout with board mounted pots and the Presence pot. I believe the only difference between V2 and V3 is a switchable internal LT1054-based voltage doubler in the V3. Given that those can be somewhat expensive and I know you all have different preferences when it comes to voltage doublers, I've left the charge pump out. If you want to make a V2, just ignore all this chatter about voltage doublers and just build the layout below. If you want to make a V3, wire lug 2 of a SPDT toggle switch to the +9/18v pad of the layout below, then wire lug 1 to +9v and lug 3 to the output of your voltage doubler. Here's the schematic this is based on.
Just waiting on some parts and I'm going to give this one a try. I can run it off of an 18v output on my power supply, so I don't really need to run a charge pump.
ReplyDeleteHas anybody had good/bad experiences with charge pumps in their builds? I'm just starting to read the (many) threads on the subject and I'd like to take any direct input... particularly using the layouts that David has posted here.
If you've already got an 18v supply, yeah, don't mess with a charge pump. They have their place and can be very useful, but can be noisy and good charge pumps can be pricy. I haven't had any issue with the few charge pumps I've built (all from my own layouts), but I think that's come down to using good chips (and possibly being lucky? lol).
DeleteThanks for the input! For the sake of experimentation and my own education, I think I'll make a couple builds just to try your add-on charge pump.
DeleteI've noticed the huge difference in price range when it comes to LT1054's posted on eBay. I'll avoid grabbing for the less expensive IC's (I have been known to be a cheap bastard).
Verified... as-is, without any charge pump.
ReplyDeleteI followed the drain voltages posted elsewhere and it sounded pretty good from the first try. Q1:4v Q2:5v Q5:5.35v
I'll likely play with it and see if I can tweak it some more. My J201's are from eBay and I'm not sure how good they are. I'm getting some Osh Park boards for the SMD J201's and will try swapping things around for fun when I get a chance.
Now that I've had time to play around with it I have to say, even with my cheap J201's (purchased from Polida2008 on eBay), this pedal sounds great.
ReplyDeleteI'm working on this but don't have 220uf caps. Are they necessary or just gross overkill?
ReplyDeleteTo clarify: I'm just verifying that I can use 100uf without affecting the tone/character of the pedal. Thanks!
DeleteYeah a 100uF is probably fine.
DeleteIt would be ok if I replace the 47r resistor with to 100r in parallel?
ReplyDeleteYou can or a 100Ω resistor will be fine there as well
DeleteIn my opinion this pedal is too muddy especially on 18V. I improved that by changing two 100n caps to 10n, two 22k resistors on the end of signal path to 10k and replace 100p treble cap to 4n7 as it is in real Marshall Super Lead. Now it sounds almost identical to my real Marshall preamps. Regards!
ReplyDelete