So I built a Marvel Drive according to the following layout:
http://3.bp.blogspot.com/-I-byi8Pvf1o/VI8dGysCHlI/AAAAAAAADZo/07-C-4tjHDo/s1600/Marvel%2BDrive.png
This layout look like based on the following schematic:
https://goo.gl/photos/rAuUy71ut7VcyRQd7
My build working great and it sound fantastic. The problem is that the "normal" and "treble" volume is not that distinguishable. (yes they has different). Both sound a bit to muddy to my ears. Just wonder how can I mods the circuit to at least make the "treble" volume less muddy? Thanks
What do you mean when you say muddy? Is the low end loose or?
Quote from: J0K3RX on September 08, 2016, 11:37:29 AM
What do you mean when you say muddy? Is the low end loose or?
I feel too many bass in this circuit. I find that I always turn the "treble" volume all the way up and "normal" all the way down. I want to lower the bass respond in the "treble" route to clear everything up.
Change the 22n cap C5 on the schematic to 2.2n and see if that helps. Also try something lower for C3...
I believe it's a copy of this...
(https://dl.dropboxusercontent.com/u/11178619/Marshall/Marshall%20Dual.JPG)
could try to replace R7 and R5 with a pot to adjust one side to be a little more or less dominant in the mix... Also, you could just modify the second-order lp filter before the volume pot..
Reduce C11 C13 to 10nFd or 1nFd.
I tried to place a capacitor either on the beginning or at the end of the circuit. I even change C11 C13 into 1nf but seem that there are no noticeable different at the low end. It is quite strange because according to the calculation it supposed to cut very much low frequency. But the mods seem doesn't work on this circuit?
Did you try the presence control like the Marvel 3?
(https://dl.dropboxusercontent.com/u/11178619/Ramble%20FX/presence.JPG)
Quote from: J0K3RX on September 09, 2016, 02:02:22 AM
Did you try the presence control like the Marvel 3?
(https://dl.dropboxusercontent.com/u/11178619/Ramble%20FX/presence.JPG)
Sure. Again I found that I always leave the pot at maximum setting.
Would you mind telling me the source of this schematic? I found that the component value is slight different from my mods. I may found some hints if you can let me know the source of the schematic.
Hello guys. Sorry for late reaction to this topic, I just saw you are having same problem as I did few years ago. Just change last two 2.2nf capacitors to 470pf. These two guys create awful low pass filter around 1447.6hz , I think someone was making a practical joke when drawing this schematic :icon_lol:
That's so funny , super low pass filter
Sent from my iPhone using Tapatalk
Hi
A question
This scheme has no input and output buffers, which are desirable for preserving the tone.
Tell me, how are things at this pedal with input and output impedances?
What are their sizes
Does it make sense to add buffers or input impedance is 1 megohm and the output does not exceed 10 kilo ohms
If you replace the last 50K resistor in the circuit at the output with a pot, you have a presence control. There's 2 1k5Hz LPF in series creating a 12db per octave filter. So everything above 1k5Hz is attenuated. If that's not enough, you can try a dual gang 50k and replace both of those 50k resistors at the end, or just change the value of the resistors to like 22k~27k to move the cutoff point around 2k5Khz~3Khz. Or even omit one of the filters. You could cut a trace and stack the filters so that the input and outputs (of the filters) are paralleled and that will make it a 6db per octave filter with a cutoff at about 6KHz. There's plenty of treble in there, it's just filtered out at the output section. Probably gets kinda shrill and harsh if you crank the treble side though.
I'm in the process of building this one as well, i'd Like to add a presence control like v2 and v3 but I'm reading conflicting information regarding the presence control. You say you can achieve the presence control by replacing the last 50k resistor with a pot, however I also read that this done by using a 20-25k linear pot and take the Master 3 wire (from the board) and solder it to Presence lug 3, conect Presence 2 to Master 3 (in this case, straight on the pot) and solder a 22nF capacitor from Presence 1 to ground. The output wire still Master lug 2 as per below:
http://effectslayouts.blogspot.com.au/2014/12/ramble-fx-marvel-drive-v1.html?m=1
I can't seem to find a v2 or v3 schematic, which way is correct? Cheers
The second way you describe isn't gonna bring any high end back into it, only filter more out. There's more than one way to skin a cat, as they say. I know my method works and with the pot fully counterclockwise is exactly as having not changed anything. So if you change it and decide, oh I prefer it the other way, you just turn a knob and that's it. If for whatever reason you feel the pedal has too much treble content as is, then the second method would be what you want as the way I did it won't cut any more treble than without having it. It just allows you to move the cutoff point of the second filter, which for me achieved my desired goal which was to bring more high end back. I'm sure you've figured it out by now, and as you might notice I don't check these boards too often, sorry bout that, but better late than never I suppose. For anyone else mulling it over, just breadboard it and see. It's a simple enough circuit and it'll make designing your layout easier than trying to cram an extra control in later, lol. Learn from my mistakes young padiwans. This is not the post you're looking for. Move along.