Building Pete Cornish tb-83 treble booster...

[dave5152]

Hi guys

Does anybody know what kind of capacitors are used in the original tb83? I know that there are two axial electrolytic caps(100uf and 47uf), but I have no idea what others are.

Schem's in this post
https://www.diystompboxes.com/smfforum/index.php?topic=112790.40








Thanks^^

[antonis]

Hi & Welcome.. 

If you're looking for mojo "things" you should also wonder about carbon special composition resistors..

P.S.
Paper in oil caps are (were) much bigger than those in photo..

[dave5152]

Thank you for answering
I've got to try using carbon composition resisters first!

--------

Then, could it be a film cap?

[willienillie]

What did he have against Duracell?

[dave5152]

Didn't expect that lol

[antonis]

Then, could it be a film cap?

Probaly, yes..!!

[dave5152]

Thanks a lot!
Maybe i should make two different versions(pio and film) and compare each other. Or put lottery switch like dallas rangemaster.
Have a nice day(?)


(TMI : I live in Korea so I don't know what time it is where you live;

[antonis]

Have a nice day(?)
(TMI : I live in Korea so I don't know what time it is where you live;

Definatelly here is more day than there..
(16:27 sharp..)

[iainpunk]

What did he have against Duracell?

duracell doesn't have more charge than other batteries, but the voltage stays near 95% until the very last bit of charge and then drops to 0 very quickly, instead of gradually going lower and lower.
normally, you can see the led darken and the sound get more and more compressed, this warns you to replace the barrery, Duracell doesn't warn you, it will just cut out during a gig.
[yes i have had this happen to me]

cheers, Iain

[willienillie]

Huh.  I thought alkaline was alkaline.

[dave5152]

What did he have against Duracell?

duracell doesn't have more charge than other batteries, but the voltage stays near 95% until the very last bit of charge and then drops to 0 very quickly, instead of gradually going lower and lower.
normally, you can see the led darken and the sound get more and more compressed, this warns you to replace the barrery, Duracell doesn't warn you, it will just cut out during a gig.
[yes i have had this happen to me]

cheers, Iain

Interesting! Thanks for the details:)
Then, what kind of battery should i use for this pedal?
Can you recomend one?

[aumnix_1]

I love treble boosters, i use the runoffgroove omega which can be biased to be a treble booster and a full range

[dave5152]

BTW, I heard (on youtube) that there' a simple cap mod on the input of this pedal. On his vid he said putting a 12nF cap 'across' the input jack can clean up the bassy low freq and add some crisps on the high.
Do I just have to add a cap between the tip of the input jack and the 'IN' of the pcb?
Is there anybody who have tried this mod before?

[dave5152]

I love treble boosters, i use the runoffgroove omega which can be biased to be a treble booster and a full range

Nice! Is it based on a rangemaster? What kind of tb is ist?

[antonis]

BTW, I heard (on youtube) that there' a simple cap mod on the input of this pedal. On his vid he said putting a 12nF cap 'across' the input jack can clean up the bassy low freq and add some crisps on the high.
Do I just have to add a cap between the tip of the input jack and the 'IN' of the pcb?

Didn't see the video but for bass "cleaning" at the input jack, respective cap has to be wired between IN and GND.. (Tip - Sleeve)
(same stands for PCB IN & GND, of course..)

Cap value depends on -3dB cut-off frequency of interest and is set by 0.159/R*C*f, where C = capacity in farads, f = frequency in Hz and R = guitar (or previous stage) output impedance in Ohms..
(actually, C forms a Low Pass Filter with R..)

[dave5152]

BTW, I heard (on youtube) that there' a simple cap mod on the input of this pedal. On his vid he said putting a 12nF cap 'across' the input jack can clean up the bassy low freq and add some crisps on the high.
Do I just have to add a cap between the tip of the input jack and the 'IN' of the pcb?

Didn't see the video but for bass "cleaning" at the input jack, respective cap has to be wired between IN and GND.. (Tip - Sleeve)
(same stands for PCB IN & GND, of course..)

Cap value depends on -3dB cut-off frequency of interest and is set by 0.159/R*C*f, where C = capacity in farads, f = frequency in Hz and R = guitar (or previous stage) output impedance in Ohms..
(actually, C forms a Low Pass Filter with R..)

Wow!
Then, you mean that smaller C value to make for more freq cut off?

Actually don't know much about the electronics;; I'm learning from you
Thanks for the discription. Helped a lot:)

[antonis]

Actually don't know much about the electronics;; I'm learning from you

Good for you but ALWAYS have a discerning mind on what you read.. 

For instance, what I've said above strongly depends on the "bassy cleaning up" interpretation..
Followed by "add some crisps on the high" establishes exactly the OPPOSITE of what I've thought (and said) on a first glance (and on 6^th tsipouro.. )

You actually call for HIGH pass filter (bass cut) so cap shoud be wired IN SERIES with effect input (between Jack Tip and circuit input) to form HPF with 120k shunting to GND resistor..
Capacitor value calculation formula also stands here so it's more easy to calculate it with 120k given R value..

Of course, it should be easier to just alter circuit's input cap value (4.7nF) for equivalent result but both value calculation and PCB intervention  are more complicated than simply "externally" adding an item..

P.S.
Double check what I said 'cause typping time is on 12^th tsipouro..

[dave5152]

Haha thanks
After some research I found that a Greg Fryer tb deluxe uses 4.7nF cap for the input! Maybe that is the circuit modified "internally".
Original tb83's circuit is covered with epoxy, so the man i saw on the vid would also have put the cap externally.
Again, thanks a lot:)

+ this is the vid i watched on youtube;)
https://m.youtube.com/watch?v=QPdIqgzpzo8