About Alembic Stratoblaster [solved]

[mecmast]

Hi all,

I'm out of 1.5uf caps. I need to build alembic stratoblaster. Is there any option using another cap or something/way instead of using "1.5uf" cap?

Thanks.

[GuyB]

Hi all,

I'm out of 1.5uf caps. I need to build alembic stratoblaster. Is there any option using another cap or something/way instead of using "1.5uf" cap?

Thanks.

Almost any value will work as the output cap, smaller values give more treble, larger value more lower frequencies.

[mecmast]

Thank you

[Nocentelli]

[url][/url]The stratoblaster is a nice little booster, but there are a couple of issues with the design and with that layout:
First off, a 50k pot is too big and does not start to boost until you get below 12.5k, which is three-quarters of the way up, or around 2 o'clock, and the boost region is all bunched up in the remaining quarter-turn. A 50k reverse log, or even better 20 or 25k rev log gives a much better response. That layout is nice and small, but all the resistors will be standing (i have no issue with that, but it looks a bit ugly and on a practical note is trickier to solder them in). It also has two grounds, which isn't ideal, but i assume it's to keep the layout tiny. A bigger problem is the two caps side-by-side at the top. Unless you've got super high value multilayer ceramics (i've never seen them as big as 10uF), you'll be using electrolytics and you'll struggle to get them in and seated properly and not leaning over at a crazy drunken angle. I'd be tempted to add a strip above for ground, rotate the 10u 90 degrees and move the output resistor to the new ground. Either that or do your own layout as a learning exercise.

[mecmast]

I've used 50k lin. pot. and 2.2uf... It didnt work. No sound. I guess something is really wrong with the layout.

I agree with ground issue and caps. Is there a verified layout for this project or any other simple J201 project? Would you mind helping me?

Thanks for the replies.

[Nocentelli]

The layout is fine as drawn, just make sure you have made the cuts on the copper tracks - There is a cut under every component in column 4 you might have missed, it's hard to make them out. If you did make these cuts, there is some other problem with your build. The ground, cap and pot issues I mentioned would not stop it working. There are other layouts - look at the bottom of this page where related topics are listed: I did a layout I called the Astrobooster based on this circuit. However, I wouldn't rush into building a different layout just because you can't get this one to work. It may be, if you made the cuts, the problem stems from a different mistake you may repeat on another layout.

Check the cuts are made and are all clean; check you have +9v and ground where you should have them; check the guitar is connected and the output is connected; check the JFET is installed the right way (if it's a J201 or 2N5457, the pin out on the layout is correct); check the voltage at the collector is around 4-7 volts and you should have sound. Report back. Good luck.

[mecmast]

Then you're right. I am sure did a mistake with the board. I have only this kinda board, so i have to make the ways by solder. Thanks for the reply. I'll give another try.

[Nocentelli]

If you have no success debugging your current build (and I urge you to try) and you only have perfboard, there are several perf layouts around e.g.

http://www.aronnelson.com/gallery/main. ... 1.gif.html

[mecmast]

Thank you for this layout, guess i am gonna build this one. But i'll wait until my components arrive that i've purchased 2 days ago.

I don't have mono jacks so i've tried to solder them...and a lot of equivalent stuff Better i'll wait for the components.

I'll report back asap my shipment arrives.

Regards.

[mecmast]

Hi,

My components has arrived and i've built the project.

I've uploaded the layout i've used as an attachment. And the photo of my build.

@Nocentelli

As you've said, the 50k volume pot. is not effective at all.

Everything is perfect now, but there are two things i gotta ask.

1. What must i use instead of 50k pot. to get it work effectively?
2. At max. volume, the sound gets distorted. Is it normal, or could it be fixed?

End of all, i want to thank to especially you. If you didn't show the way, i shouldn't be able to build this project.

[Nocentelli]

1. What must i use instead of 50k pot. to get it work effectively?

20 or 25k rev log gives a much better response

If you don't have those values in rev log, try linear. If you don't have those value pots at all, try putting a 33k across the two lugs of the 50k pot: This will give a 20k pot.

2. At max. volume, the sound gets distorted. Is it normal, or could it be fixed?

Hmm, I can't really remember if mine distorted particularly: I don't think I used it fully up. It may well be operating outside the normal linear region, and is might be clipping the signal within the JFET. However, at maximum volume the boosted guitar signal would be hitting the input of your amp pretty hard, so it is difficult to tell whether it is the JFET, or the amp, or both that are distorting.