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Started by dazz, January 04, 2018, 08:53:12 AM
Quote from: Katoda on January 30, 2018, 03:37:46 PM :lmao: I wasn't expecting that at all If everything is securely in place and it won't move, then I guess it's OK. If the brown empty pcb is intented for the preamp, then you might have some mains hum when it gets amplified through it. Keep the input signal as far away as possible from that psu.+1 for creativity
Quote from: dazz on January 30, 2018, 05:09:13 PMQuote from: Katoda on January 30, 2018, 03:37:46 PM :lmao: I wasn't expecting that at all If everything is securely in place and it won't move, then I guess it's OK. If the brown empty pcb is intented for the preamp, then you might have some mains hum when it gets amplified through it. Keep the input signal as far away as possible from that psu.+1 for creativity Yes, that's where the preamp will go. I'll move the input jack farther away from the PSU and the PCB input will sit right underneath it, so the wire will be a few millimeter long, like 12 mm or so. Hope that works just fine. I guess I should have mounted the PSU with the mains facing the opposite side. Will fix that. Man, I appreciate your input, really do, Thank you!
Quote from: phatt on January 12, 2018, 07:19:34 AMyes I guess any low signal circuit could be termed a preamp but a lot of them will colour the sound in a negative way and because it's hard wired into the Amp you are stuck with one sound only.I'm yet to meet a guitar player who is happy with all 2/3 channels of his Amp. :lmao:What you need is a 2 or 3 stage preamp the first matching the guitar with some gain and the second stage runs a tone control.If the tone is passive then you have to adjust the gain to pull up the signal loss in stage 2.This can be done with one dual opamp running single or dual supply.Those fancy circuits with a whole pile of parts is just going to be a nightmare for the novice. (hint)BTW, I have tested that vulcan circuit and it's not that great,, as a pedal effect it may help but there are likely better (easier) ways for simulating the valve sound.Be aware of sound clips as they can be misleading,, a lot of demos are just $20 distortion circuits (that have been around for years) plugged into Valve amplifiers that most of us can't afford to even look at. They hit the pedal and your hear a sound to die for. <3) <3) <3)So you go buy that pedal and plug into a small budget bedroom SS amp and it sounds nothing like the demo,, most will feel ripped off. :grr :grr :grrReality; Almost any crap dirt pedal will sound stunning through a big monster Valve Amp,, But not quite so easy to do with all SS rigs,, though some Can do that trick.Reason;With any half decent Valve amp you only have to send it a bigger signal from any old dirt pedal and the Valves do the magic because of the way they work.(A whole other subject that has filled many books)This magic trick will never happen with a small simple design bedroom SS Amp combo with a 6 inch speaker. So with All SS circuitry you need to do a lot of fancy circuit tricks to get same or similar outcomes. A SS power stage is very different to a Valve power stage and most SS Pwr stages won't compress like a Valve rig so you have to do most of the tricks in the pre stages.MY advice is build a basic preamp, a single clean channel is good because you have a basic clean sound which is not too coloured. You then try out different pedal circuits which work with your Amp.I have a simple Casino bedroom Amp here (read Cheap) and with a few tweaks itactually sounds ok through a small speaker but much better through my quad box. :dbtu:The added dirt circuit is not brilliant but the clean is good.I've tweaked the tone shaping to wipe off the excess hi freq that these small amps produce which gives a much smoother sound but don't be fooled there is more treble than you will ever need ,,unless you have tin ears.hope it helps,, Phil.
Quote from: phatt on February 12, 2018, 06:21:53 AMYes any of the usual opamps will do the same job give or take an electron but TL07X is likely a better chip than lm4558.The TL082 has low current draw which might be good for battery powered circuits but that is not needed in a wall powered unit.But yes use those if you wish.The LM833 is aimed at audio and is a top shelf chip. :tu:I doubt you will note much difference in performance with any of the usual chips.Heck it's a guitar amp so the last thing you want is 20/20 bandwidth. The LM386 is powerchip and not really much use in the preamp unless you want it for some special booster. I can't remember the name but a couple of pedals use those to get big distortion sounds.Others here may recall those circuits??Phil.
Quote from: phatt on February 12, 2018, 07:44:55 PMRe the clean channel, Yes everything in green box is correct.Oh I just realized that you obviously have a single 12 volt supply,, in which case you will need to alter the Casino circuit as it assumes split supply.You will need a bias voltage, look at pedal circuits for clues.If you can't work it out I'll redraw the schematic for single supply.Re the 2nd half of the power chip,, just leave the pins open as it will just idle with no load and not draw much power from the supply.with some chips you can just ground the input to be sure nothing weird happens.Phil.
Quote from: phatt on February 14, 2018, 01:15:02 AMHere you go Dazz, :tu:Try this out, it should work and deliver plenty of signal to the power amp section.If you breadboard this first then you can tweak some of the values to taste. Cheers, Phil.