[Billy]

We’d need to see and be able to trace the wiring to your DC jack, 3PDT switch and in and out jacks

Your image is a bit out of focus and you can’t clearly see all the values and resistor colour bands

[Billy]

My Q3 is biased at 8.4v and works fine the source resistance change will affect it a little, 1, 2 and 4 biased to 5v and Q5 to around 8v

You’ll notice Q3 and 5 have no source bypass cap so gain is set by Q1, 2 and 4 making them important to bias at 5v ish

 

[Billy]

Yeah definitely a gain monster

You can still go to major sustain approaching feedback sounds with guitar volume cranked up

I’d checked other layouts most of which suggested A1M with R11 at 12K but that didn’t make a lot of difference the gain range was still bunched up

I found very little difference between the A250 and 300K pots with R11 at 100K to me it was slight, the 250K I thought gave the least difference in tone

With some of the other values bass increased around halfway for a small portion of the range but with a 250K tone remained constant throughout the pots rotation

It’s down to personal preference but both the 250 and 300K worked well try both but as I say not a lot of difference gain is more gradual up to halfway but you can still hear a difference after halfway it’s just not as obvious

You could experiment with the resistance on lug 1 I tried 4K7 which was fine to me then decided to measure the resistance between 1 and 2 where level dropped out which as I said was 5K5

I’ve sent some clips on spacebook messenger

Stock values

Pot change only to A250K

Pot A250K and R11 100K

 

 

 

[Billy]

No, A250K works fine

It definitely made a difference across the gain pot range but what I would say is it’s a gain monster so you wont notice much difference nearer the middle of the range and using your guitar volume also has an affect as you’d expect

I just tried again with a A250K pot actual resistance 248K this time I measured the resistance on lug 1 to 2 fully CCW where the signal is as clean as you’ll get it and level doesn’t drastically drop out, it read 5.5K so lug 1 resistance anything between 5K5 to 8K2

 

 

[Billy]

No if you’re using a 500K you’d still put the 1M in parallel across lugs 1 and 3

R11 yes 100K

Lug 1 of the gain pot needs some resistance to stop it cutting audio level when fully CCW

8K2 was suggested

Note I tried a few different pot values and tapers and R11 values detailed above

Now if I’d read all comments fully I’d have seen Barry already detailed what the DC movie guy did and noted he’d already put resistance on lug 1

What I tried confirms what the DC movie guy did will work

If you use an A250K gain pot then you wouldn’t need the paralell resistance across lugs 1 and 3 if you use an A500K then put a 1M across lugs 1 and 3

Make R11 100K and add 8K2 to lug 1 and you’ll be good to go

Here’s a wee pic my test set up for info

 

[Billy]

Yes I mean your circuit power and ground wires and audio carrying wires at the bottom right of the pcb you have your blue out tip wire and 9v and ground wires twisted

It can lead to parasitic oscillation so ideally you want your wires as short as possible and audio and power wires as far away from each other as possible

You could try wiggling the wires with something non conductive like a pencil to see if it affects the noise and helps you identify the cause

 

 

[Billy]

What kind of noise is it

With you turning the LFO off via the killswitch that may indicate it’s not the LFO causing the noise

I would try to separate your power and audio wires If they have to cross over each other make sure they cross like this + and don’t run in parallel like this =

[Billy]

Built stock

I tried A,B, 1M  A, B, C 500K, and A and B 250K

R11 from stock 3K9 then 10K, 12K, 47K, 68K, 100K and 1M

The best result I found with the values I had on hand

A250K (actual resistance was 219.4K) with 100K at R11

although all other values from 12K to a 100K with an A250K made gain more gradual but I definitely thought 100K sounded best with the least amount of tone change and a more gradual change over the gain pot range

I’d advise some resistance from gain lug 1 to ground it being wired as a voltage divider as you’d expect when completely CCW volume drops a lot

When I get a moment I’ll try a 300K pot and 100K at R11

I looked at other layouts most used an A1M pot with 3K9 at R11 some advised trying an A1M with 12K but it didn’t make it more gradual to me

* tried an A500K with paralell 1M actual resistance 312K and R11 at 100K

I didn’t think there was a lot of difference to the A250K

 

[Billy]

Yes R11

I’m still messing with it got a couple more pot / resistor combos to try when I’m finished work and I’ll report back

 

[Billy]

Hi Rebecca

Its fairly difficult to trace your jack wiring its hard to tell whether your I and O black wires go to your jack ground lugs

Do you get bypassed sound

What are the colour bands on R3

[Billy]

Excellent Jimi and I’ve got a D’lay or 2

So I’ll give this a go tout de suite

All the best in the new year y’all

 

[Billy]

Meant to say I checked what I could see and everything looked good

You won’t get accurate resistance readings in circuit because of connected series and paralell resistance

Just for info when checking resistance along a circuit  path always make sure there is no power to the circuit for example if you wanted to check resistance on the path between +9v and IC4A pin 3 you’d expect at least  180K (R26) + perhaps some of R27 68K

Try it yourself and see what you get I’m never sure with series resistance

[Billy]

R26 looks like a 180 ohms not 180K ohms

Colour bands should be brown grey black orange brown

Yours looks like brown grey black black brown

Check all resistor values by colour band make sure they’re correct here

https://samstechlib.com/610938/en/

 

 

[Billy]

Should be fine Shane

Someone here used a passive eq with it

https://www.buildyourownguitar.com.au/forum/showthread.php?t=10817

 

 

[Billy]

Post some nice clear pictures of your build so we can see all components clearly

Check components from pin 3 of the 4047 to pin 1 of the 358

 

[Billy]

Merry Christmas Ray and everyone

Hope you all have a splendid time and get a few down you

All the very best to you all

[Billy]

I’m defo around a 100

Majority from here

Some probably 10 years old and a good few freebies from the man himself

That doesn’t include etched boards maybe 35 of them alone

Or the ones I keep like Barry’s etched 3PDT board and mu amp from waaaaay back

Edit because I’m such a sad individual I counted what I could find although I know there’s a bag or 2 of the ones I was gonna build next

GPCB 52 not including mod boards

Miscellaneous 33

Five cats pedals 27

Etched 27 these are purchased not etched by me

Pedalpcb 6

Total 145

A lot I’ve had for years if I count the ones I’ve 2 or 3 of you could defo add another 40

 

 

 

[Author]

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