rod elliot project 27 preamp

[kin0]

hay,

I wanna build this preamp for the clean channel but I have some problems.

1. Is it okay that my power supply will be 14-16v?
2. What caps to use? And if I need electrolityc where is the +?
3. This is the poweramp http://www.vellemanusa.com/downloads/0/illustrated/illustrated_assembly_manual_k4001.pdf. Can I use the same power supply as it is drown in page 7 (just that I'll get 14-16v out of it?
4. How can I do the switching with dpdt between this preamp and a shredmaster (the dist channel)? (I thought that one will be for the output) but how to change the power (it's different voltages).
5.Will there be differnce in volume between the two?
6. I drew a new schematic to turn it into a pcb can you heck if it is fine?

[phatt]

Hi kin0,
        Judging by the comments ,,you are likely out of your depth.
You might be far better served by building the ESP preamp and running the other circuit as a pedal.

The Vellerman power chip kit is only a small wattage unit and the complexity of the preamp setup you wish to design is overkill for such a small Poweramp.
If you wish to mix and match circuits DON"T go buying PCB's and think you can swap a few things and have it magically work first go.

If this is your aim then wether you know it or not you entering the world of *design* and that can test the patience of even the most hardend electronics freaks.
Sadly this modern SS PCB world might look easy to hot wire some cheap circuits and achieve tone heaven but,,,,,

30 years ago I was asking the same Q's as you have here.
In 30 years of fiddling with stuff I've only had about 4 success stories. Needless to say
I now have a shed full of DUD circuits. What is not used as spare parts will one day become landfill.
Take my word for it (my shed is proof) it is not as simple as it seems.

Rod E has gone to considerable effort to make the circuit work and the average joe will waste lots of solder to even come close to building a circuit as good as His.
Yes it's still not "the perfect" SS Amp but in your situation build the ESP As shown **FIRST**
Then as you learn more you can move on to the bigger more complex side of Audio circuits.
ESP circuit will be a good workhorse Amp that will run reliably and give no grief if built well.

If you are serious about designing your own stuff then go purchase a bread board and some jumper wires as these will save 100's of hours of wasted time trying to refine circuits.

I still use my BBoards,, when I get an idea I just whip up a quick circuit and test it out.
If I like it **Only Then** Do you start to plan for PCB's and other stuff.

If you want a good circuit don't take shortcuts.

The only short-cut worth taking is if someone has built Exactly what you want and has at least one working circuit,, preferably a lot more.
Then you might take a chance.

meantime Read Teemu's PDF Book on SS Amps,,, download from this site ,,,an REeeeAD.
Cheers, Phil.

[kin0]

Okay thanks for the comment. I send his book for printing two days ago (I just can't read from the computer). I am going to start working on my own designs (first I'll start with km386 amps and pedals and then go to more complicated stuff) but first I wanted to build a project to understand a little bit. I understood that it's fine to build a small poweramp (chipamp) and to use a pedal as a preamp. The problem is I can't find any clean stompbox to work as a clean preamp (it can distort to a little drive)

[phatt]

Hi kin0,
            I'm not the expert with this LM386 chip but experience tells me most 1 or 2 watts chips Amps are not likely to have a clean sound no matter what preamp you insert in front.

You may need a 10 watt poweramp before you get a useable clean sound.
Phil.

[kin0]

Yea I said that after I am done with this one first I'll do a lm386 amp.

[kin0]

Hay,

I don't what will function better as a preamp (before a velleman kit). I have 2 ideas

1. Use buffer----> baxandall tone stack --------> preamp http://www.till.com/articles/GuitarPreamp/ -----> volume control -------> poweramp. Some people told me it will be very transprent

1. Use buffer----> baxandall tone stack --------> booster (lpb-1 ?) -----> volume control -------> poweramp. I am not sure how will it work but I think because the lpb-1 isn't transprent at all it will be less transprent then the first one.

any ideas what will work better?
oh and also any ideas for a good buffer?

[Manfred]

Hi,

the value of R14 is unidentifiable in the schematic, what is the value.

cheers, Manfred

[J M Fahey]

HiManfred.
Go straight to Rod Elliott's Project 27 preamp; the schematic posted above looks like an Eagle PCB schematic, the first step to design the board.
Rod E. actually sells the boards, for a small price to help pay for his site's costs, so it's actually fair to buy something from him.
Besides, it will be actually cheaper than having just 1 board made, which carries a "setup" fee.
As an example, Express PCB did ask (prices may have gotten up) U$56 for 3 little boards, minimum price.
Price for just one?: U$56.
I think Rod asks for far less than that, given that he probably orders them in 50 or 100 batches.
As of that resistor's value, it must be between 470 ohms and zero; higher values give softer distortion; lower (or 0) harder.
Just a little to make the amp more suitable for guitar; for serious distortion you should use your favorite pedal (at least the classic and very simple MXR Distortion +)

[phatt]

Hay,

I don't what will function better as a preamp (before a velleman kit). I have 2 ideas

1. Use buffer----> baxandall tone stack --------> preamp http://www.till.com/articles/GuitarPreamp/ -----> volume control -------> poweramp. Some people told me it will be very transprent

1. Use buffer----> baxandall tone stack --------> booster (lpb-1 ?) -----> volume control -------> poweramp. I am not sure how will it work but I think because the lpb-1 isn't transprent at all it will be less transprent then the first one.

any ideas what will work better?
oh and also any ideas for a good buffer?

The Tillman circuit is meant as a small (onboard) front end and is not intended as a preamp input stage of a guitar Amp. Its real purpose is to overcome leed losses associated with long guitar cords.
By itself it is only a buffer and has no gain.
Phil.