Depending on what kind of led you use, you might need to use a current-limiting resistor as high as maybe 47k for one of those very bright 3mm blue leds, best thing to do is do some breadboard experimenting with different resistor values first.
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Depending on what kind of led you use, you might need to use a current-limiting resistor as high as maybe 47k for one of those very bright 3mm blue leds, best thing to do is do some breadboard experimenting with different resistor values first.
Quote:
Originally Posted by JohnH
Yeah that's true, I think the 22uF/450V caps are a bit smaller than a 47uF/450V cap, so if you put two in parallel you'll effectively get a 44uF/450V cap.
Yeah, there is a huge variation in available LED brightness. I always breadboard the resistors since my box of LEDs vary quite a bit in brightness by colour, and also to a lesser extent within a colour. Blue tends towards the bright side. I suspect it's due to the complex shenanigans required to get a blue colour.Quote:
Originally Posted by DrNomis_44
'True bypass' avoids any connection of the input signal to the circuit, and on this pedal as shown, the signal is still connected when in bypass mode. It may or may not not alter the sound, but for some true bypass freaks, it won't be acceptable.
Take an extreme case of the circuit simply consisting of a capacitor connected to ground (like the tone circuit on a guitar but with the pot set to 0). Then the capacitor would still affect the tone of the signal in both 'in' and 'bypass' switch positions. You'd need the input signal and the output signal to be disconnected for the circuit not to affect the tone.
The circuit as shown doesn't disconnect the input from the circuit, so isn't even the 'basic true bypass' of the linked article. It's just a bypass. Semantics maybe, but still important as you are reliant on the design of the circuit not to noticeably affect the tone in bypass. And there could also be knock-on effects with respect to increased ground loop noise with some circuit designs.
For this circuit, you've got a 1M ohm resistor down to ground that's certainly connected in bypass. This will be in parallel to the amp's input impedance, so assuming that is 1M, you've now got 500 k Ohm. Still pretty much OK. But assume there are several other pedals with a similar bypass design. You can easily drop down to a 250k ohm or below equivalent input impedance, which will start loosing top end if there's no buffered circuit upstream.
So I'd definitely recommend using a 3PDT switch so you can call it true bypass.
OK, I see your point and gracefully concede :)
/me goes back to check my bypass wiring ...
Yeah, the scheme I use connects the effect send (input) to ground, and leaves the effect return (output) disconnected in the bypass state.
A bit of a mental exercise for me as well. I can now see why people insist on either a good buffer or a true bypass switch.
I prefer true bypass and separate buffer pedals. That way I avoid the issues caused by too many buffers (I watched a video where they hooked a bunch of Boss pedals together, all buffered - the audio result with all pedals bypassed was not pretty) or not enough, and I get to choose where the buffer goes.
It's also why I use a trusted wiring diagram each time. I don't need to rethink this, just follow the instructions.
Some of the Boss designs haven't changed since they were designed in the 70s/80s, and buffer design has moved on considerably since. There's no reason why a good modern buffered pedal shouldn't be totally transparent in bypass.
It's embarrassing it's taken so long to finally box this up, but I thought I'd share the final product with you all...
I definitely recommend building one of these - it's a lot of fun to play
Attachment 40627
Looks great.
Well, I've just placed an order with Tayda, so my tube driver build is now officially underway (as opposed to being unofficially underway, as it has been for the last year or so ;-)
John, I love your idea of using a U-Bolt to give the tube some protection - I'll be doing the same. Do you recall what size bolts you used? In non-pandemic conditions, I'd take a tube to Bunnings and eyeball them, but that's obviously not possible in Sydney at the moment.Quote:
Originally Posted by JohnH
Also, do you have any photos of the internal layout of your pedal by any chance? I'm trying to work out how to fit everything into the enclosure, and I'm currently planning to include the full tone stack, so I'll have three extra pots as well.
Well, this wasn't exactly a _quick_ valve fuzz pedal!
Attachment 45876
I gave up on trying to get the full tone stack in, as I was rather short of space.
Attachment 45877
Here's the circuit I ended up with. The charge pump reaches ~68V from a 12V input.
Attachment 45878
That is just awesome. Looks great, and I imagine it sounds great.
I was thinking that one way to get a bit more room, since you are already doing some bolting, would be to bolt a small enclosure onto the side of the big one and put the tone stack there?
The U-bolt is a good idea, but if I ever break down and make one, I won't call it a "stomp box"... More of a "carefully tap with your toe box"
Thanks! It does sound good. I was expecting rather more "fuzz" than I'm getting - I have a Marshall origin 20 combo amp, which isn't very high gain at all, so my single coil guitars struggle to get much breakup even with the gain on full. This pedal fixes that ;-)Quote:
Originally Posted by fender3x
I'd probably just use a bigger box if wanting to get the tone controls in there as well. This is a 1590BB - a 1590XX might give enough space. Yes, some care is required when stomping ;-)
Have you tried it with a 12AX7?
Should do a sound demo so we can hear what it sounds like, I remember doing an experiment with the CD4069 Hex Inverter +HV Generator circuit, I was powering it off a standard 9V DC battery, and by adding extra diodes to the Voltage Multiplier circuit, I was able to get it to generate +90V DC.
The circuit should work with 12AU7/12AT7/12AX7 tubes and their equivalents that all share the same pinouts, you'll get different amounts of gain and distortion out of them.