EDIT UPDATE (for lazy people who can't scroll to the bottom):

The Octavia works! Sounds great.

I've built an EH Big Muff Pi, and that... doesn't work. I need help troubleshooting!
Scroll down to see the schematic, veroboard layout and suggest things i could do to check.


I have a schematic for the Roger Mayor Octavia. I really want to re-create the Hendrix Octave up sound and haven't built a pedal in a while.

Does anyone at all know where I can get a stripboard layout for this? short of me sitting down and working it out.

Last edited by jcwear at Sep 10, 2006,
No problem man. Good luck. I cant wait to finish my Octave so I can get an octave fuzz through my 4uzz! I can get a low octave fuzz in the 4th setting but I want a high octave one too.
Excellent, just to check those red squares with red dots, indicate where i break the track, correct?

Also the MPSA13 listed for Q2,3 & 4 are NPN Darlingtons... but what is the Maplin equivalent... Could you recomend one that you know would work?
Would BC517 work?

The red squares are trace cuts, yes.

Get your transistors from Mouser. http://www.mouser.com/search/ProductDetail.aspx?R=MPSA13virtualkey51210000 . They seriously ship out very fast and you get the exact thing you want. I placed an order on Wednesday and got my order today! They processed the order the day of me placing it and shipped it the next day.
Do these guys ship out here to the UK? Because if they did it would take forever wouldn't it? I'm thinking of just ordering everything from there if its quick and easy (and cheap!). It would be great to have a 3PDT switch too... Hoping they have those. I'll have a look i guess.

Thankyou so much for the help!
I think the Uk shipping is pretty cheap from what i can see. I'm going for it!!

Just a quick question for us electritians... 0.001uF is the same as 1nF or 1000pF right?

just checking...
i bought all the parts minus the transistors + diodes from Maplin just now. £23!!!! Better than £150 i guess lol!!

I ended buying these tantilum capactiors by accident which cost a bomb!! £2.56 for 4!! Yikes. Never mind at least they can withstand a nuclear explosion.

I'll keep people updated with everything once i written my University personal statement thingy this project will be up and running.
I got things from maplin because i was passing by it today lol. Ill just order the transistors and diodes from mouser and when i do it I'll do it in bulk, to save money if you see what i mean...

I just thought it would be easier to get other things now, certain things are cheaper like the DPDT footswitch and the stripboard and the knobs and pots and stuff.

Transistors will come soonish i hope!

S H I T!!!

Shipping costs are $31 for like 20 components? I don't think so!!!

I'm going to have to order everything from my local maplin.

In that case I need an alternative to MPSA13 from the maplin website... I really don't want to fork over $30 for parts costing me about $1.50 overall!!!


Here are the darlingtons... but which one of the NPN's should I use to be a good substitue for MPSA13?
Yep I just read that thread funnily enough!!

I prefer the layout of the rapid electronics website. I think it's going to be my main site now. All i need to do is just order my stuff and that's it! Just gotta wait for my dad to get home.

BTW This morning I was a little careless and I accidently cut a track that i shouldn't have done. Would the best option be to just literally wire a connection over the gap?
you can always have a look at banzaieffects.com they're pretty good for large orders (put in a couple of orders with them recently).
Right. Greetings all.

I have fixed all the problems on the board, it looks perfect (fingers crossed) I'll take some photos up If someone can recommend a good website to host my pictures that'll automatically resize them etc so it can be compatible with UG.

I have ordered everything I need for this project and for the EH Big Muff pedal I plan to make in the same box from: http://www.rapidonline.com/home.aspx

Parts should come in before this week is through.

I'll post pictures when someone can suggest a decent website to host my pitures.

For everyone else here who is English like myself, I would say Maplin has lots of things, infact everything you need most of the time, but anything you can't find at maplin you get at rapid electronics and vice versa.

If your lazy and don't know maplin's website / don't know how to use google ...

Hope that helps.
IT WORKS!!! THE OCTAVIA WORKS!!! Sounds friggin awesome too!!


I have also made the EH Big muff Pi, and that one isn't working... I need to know why,

here's the layout:

and here's the schematic:

Now I reckon the problem is that One of my polarised capacitors (or indeed all of them) might be the wrong way round. I need to know pretty much all of them.

Also... is 2N7000 an OK substitute for 2n5088? that might also be a reason why its not working.
not sure about the transistor, but there arent any polarised caps in there, make sure that youre diodes are the right way round.
the diodes are the right way round trust me,

i know there aren't any polarised caps in there but the values where a bit weird so i had to get some that were polarised to put in, im pretty sure i got them the right way round...

what i really need someone to help me with is the transistors because i have sinking feeling that i got the wrong bloody ones.
look up the data sheets, as long as both are NPN (or PNP though i-m pretty sure that these are NPN) then they should be fine.
well then as far as i can see, it must either be a cap round the wrong way, a bad solder joint, the transistors are the wrong way, or you've forgotten to make a break in the track, just go through and do a basic De-bug.

(mosfets are fine for this circuit, they are normally used for distortion and amps etc.)
Ill check the tracks and try and calculate the caps again!

Just a quick question, if you buy a capacitor that can withstand 1KV and put it in this circuit will it not work because there are not enough volts or should it be fine?
That's what i thought, all the tracks seem fine, I'm guessing its one of those caps. If anyone can help me with finding the polarity of those caps then that would be great!
well seeing as you have a negative ground, all the negatives SHOULD head towards the ground, well theoretically anyway.
these are my stupid polarised capacitors...


where there is a positive on that side, that leg is positive correct?
Just checking

I just don't understand, ive swapped the transistors to check the pinouts were right and all... which they are... im stumped
Last edited by jcwear at Sep 10, 2006,
I call upon anyone to give me a checklist of troubleshooting tips.
I've already tried:

1) Swapping the pinouts on the transistors
2) Checking all the track breaks and that soldering is all tidy (doesn't leak onto another track)
3) That the battery is connected

I need someone to tell me answers to the following questions:

1) Are 2N7000 MOSFets fine for replacing the 2N5088 General purpose audio amplifiers in the Original?

2) I've had to use tantalum bead capactiors [polarised ] for all the 1uF ones (That's C1, C5 and C8 - followed the ones that reportedly sounded better) I need someone to tell me if the leg with the +-- is the positive one and where positive should be facing on the layout.

3) Some of my other capacitors are stupidly large and can withstand 1KV and 250V, but they were the only ones that matched the values required so I bought them. Could this be a cause for concern, or does it just mean these components will withstand a nuclear holocaust and should still work in my circuit?
1. Use regular caps not polarized ones. if you have to order them, its better than the thing not working.
2. 2N7000 are MOSfets and usually CAN NOT be substituted for 2N5088s.
3. The voltage rating on capacitors means the maximum voltage that it can withstand. Usually anything above 50 is good enough and usually theres not much lower than 50v caps.
Hey People!

Maplin Stock BC549C which is apparently a good replacement, i read in an article from R.G. Keen. So hopefully I will have those parts. If when I put these transistors in, if things still don't work I will need more troubleshooting help.
ooops, sorry about that, i presumed that since i've seen fets used for distortions and stuff before that they would work fine, my bad!

First of all I stuck BC549C and these made it REALLY LOW GAIN like a boost pedal, then I put all 2N3904 in and It now sounds like it should do... A Big Muff Pi.

Dude this thing sounds good!! Im so pleased with my pedal builds!! Thankyou everyone for the troubleshooting help!!