[Billy]

The correct voltages for biasing Q2 collector are -4.5 to -5.5v

I personally bias by ear to where I think it sounds good and it doesn’t always read within that range, it can vary

Its worth noting that hFE, leakage and temperature all affect germanium transistors, how are you taking your readings

[Billy]

The solution to this with credit to Chuck D Bones he thought it was high frequency oscillation on Q2 or 3 and advised to place a 10K resistor in series between C7 and Tone pot lug 1 which got rid of the dead spot

[Billy]

Any germanium with around the same forward voltage will do Steve I use Russian one’s these days genuine 1N34A are extremely difficult to get

 

[Billy]

Alright Steve

There’s never a stupid question mate we all do it differently

The duo of ground and +9v pads on the 3PDT board are there to make it easier for combos etc

What you can do is wire your +9v and grounds straight from the DC jack to the 3PDT board then use the extra one’s to wire power and ground your main pcb

 

[Billy]

Welcome Tom

Take your time and enjoy creating your first effect you’ll wonder why you didn’t do it sooner!

You’ve come to the best forum out there so no matter if it fires up first time or not we’ll be happy to help

Make sure you read the guides page to get yourself off to a good start

Good luck with first your builds

[Billy]

I was hoping you’d chime in Ray!

I’d noted when I built it many moons ago the resistance on my pot from the beginning of the flat spot to the end, can’t find my notes at the moment, what I noticed is at the beginning CCW it’s low volume clean signal when you get towards the end CW more like a mis biased tranny in that if you hit it hard it comes through distorted and a little clearer and as you get to the very end it sounds more like it should with a kind of intermittent stutter

My next move was to change the transformer with a red fasel thinking I may have got one on the extreme of tolerance range looking at the datasheet the 42MT013 is + or – 10% so I thought perhaps that may cause a problem and could be why a small amount of people get this issue

I thought the problem was either a resistance change i.e the 33K being replaced by the 330K 10 times bigger and then further adjusting the tone pot resistance may cause it or the inductor

If I can find one I’ll look at a fixed wah schematic

I note the guy with the same problem on DIYSB posted that he used a charge pump for 18v and it dissapeared completely, albeit pot lug 2 still crackled when touched so again potentially a resistor change would solve it by allowing more current to flow

Anyway I’ll have a read of RGs wah technology page

Cheers mate hope yer all good

[Billy]

Sure have a few times! I’ll try some of the suggestions made on that site Mark

I’ll report back if I ever get it sorted

It was a commission for someone that obviously he never got so it’s been sitting forgotten about

Now having more time, not because of covid but because I’m off Facebook! I thought I’d throw it out there

It uses half a 42TM013 as the inductor

[Billy]

Again you can join values this time for capacitors to add up it would be in paralell but not something I do often

C9 is in the power section so 47 or 68 is fine there

C4 and 5 are again part of the Low and Mid filter network putting a 68 or 47 in C4 and a 22 in C5 wouldn’t stop the circuit working it would just alter the frequencies slightly in this case I’d go 47 for C4 and 22 for C5

Not to get too technical but you can alter resistance to compensate for cap changes but imho 22n for mids is still ok as is 47 for lows I again would just socket them and change when you get the correct values if you want to, your ears may well be happy with it

[Billy]

As I say doesn’t look great but does the job

I think I did 3 on this build only to discover I actually had all the values

This pair were the best of the bunch I’ve edited out the other 2 pairings that didn’t make the’ kinda looks ok’ grade!

[Billy]

They’ll be ok the circuit will still work

With metal film tolerance is + or – 1%

Carbon film + or – 5%

I’d probably use the 330K rather than 270K

The 3K6 I’d use the 3K9 it won’t make any noticeable difference I’d err higher because 1 is in the op amp negative feedback loop the other part of the mid filter network even though it’s K ohm it’s not significantly different

You could use sockets and try both values and if you wanted change them later

Or you can tepee, solder a 100K and a 200K in series for 300K

Any 2 values added together and soldered in series that add up to what you want will do, albeit it don’t look great

 

[Billy]

Nice Bob

You’re obviously a bit of a pro! Looks really good I’m liking the name very clever

It’s a great circuit, the one I built, the guy I get to test my pedals because he’s a gearhead with tons of cool expensive guitars and amps liked it over his Keeley baked mod TS808 and bought it immediately

So I’m awaiting another pcb this time it’s all mine

[Billy]

Looking at the schematic negative would go to gain lug 2  towards ground a quick continuity check would let you know what pad that is

It’s normally input side + to output side –

 

[Billy]

Have a look at the BTDR3H datasheet James the circuit’s based on the PT2399

There are also some fairly simple add on modulation boards that you may be able to add on I haven’t done it myself so can’t advise but I have added modulation daughter boards to delay builds

The add verb us an excellent sounding reverb with the added delay it offers lots of tones from slapback to deep cavernous cave sounds

Some discussion on belton bricks here

https://www.diystompboxes.com/smfforum/index.php?topic=109128.0

 

[Billy]

Post some pictures Henrik an image of the component side of the board so we can trace all wiring to switches, jacks etc it sounds like a loose wire somewhere if it was working before

 

 

 

[Billy]

Looks good to me for a hot mess it’s not that messy at all, the GBOF is a great little board I like your use of it

[Billy]

I built one of these currently out on loan with a local band

Its an excellent circuit and definitely one everybody should try lots of tone shaping available and I totally agree with Barry it’s the best overdrive/distortion I’ve built

So I’m happy to see it at GPCB and I’m expecting it to be even better than the one I’ve built knowing all the improvements that are always put in by Barry

I’m looking forward to seeing if this will be my new favourite GPCB board the sriracha fuzz / hot chilicon  having been my top dog for around 8 years

Incidentally I didn’t ask for feedback or anything I just said I haven’t given you a pedal to try I’ll give you the next one I build, I think that’s a wee bit of band instagram PR hype!

 

[Billy]

When zoomed in your DC jack image looks sideways if that’s the case it’s correct with battery power going to the middle lug and as you know board power to the smaller top lug

As Cybercow says it’s important when you also have a battery installed that it disconnects battery power when using an adaptor

Most but not all DC jack sockets these days disconnect the battery via a spring mechanism when you plug your adaptor into the jack

Its easy enough to continuity check to see if it is a switched type with nothing in it both power lugs should have continuity when you plug your adaptor into the DC jack they should have no continuity obviously you don’t have to plug your adaptor into the wall to test

 

[Author]

Posts