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DIY Stompboxes => Building your own stompbox => Topic started by: brujo on May 18, 2021, 05:14:12 PM

Title: BMP tonestack
Post by: brujo on May 18, 2021, 05:14:12 PM
Hi there, I have build this tonestack http://tagboardeffects.blogspot.com/2013/08/bmp-tonestack-w-lpb1.html using 33k(both ) resistors on tonestack and as capacitor a 10nF(as schematic) and a 22nF(instead of 4,7nF) and added at the end of a bc109c FF circuit (250k volume pot). I put a 330 ohm resistance instead of a 390 ohm one(BMP tonestack low right on the schematic). Rotating tonepot all counterclockwise completely cut off all the sound from the circuit,as you open , it start sounding,unleashing true tones and gain only in the second half of the rotation( very harsh tones). it's like it does not work as a tone properly, what I am not getting?

(https://i.postimg.cc/LqTKCM9M/7baf6939-4649-4e1a-9d78-8dba7923e5dd.jpg) (https://postimg.cc/LqTKCM9M)

cheers
Title: Re: BMP tonestack
Post by: antonis on May 18, 2021, 05:23:32 PM
Could you post a draft schematic/diagram instead of making us guessing or tracing layout..??  :icon_wink:
Title: Re: BMP tonestack
Post by: brujo on May 19, 2021, 07:37:25 AM
How can I do what you are asking me? :icon_redface:
Title: Re: BMP tonestack
Post by: antonis on May 19, 2021, 08:29:39 AM
Never mind...

Let it be.. :icon_wink:
Title: Re: BMP tonestack
Post by: brujo on May 19, 2021, 01:25:13 PM
 :icon_sad:
Anyway It Is a npn FF ,it's volume output go trough the in of the tonestack. This Is the layout of the fuzzface..https://www.google.com/search?q=sunface+veroboard&oq=sunface+veroboard&aqs=chrome..69i57j33i160.5025j0j7&client=ms-android-oppo-rev1&sourceid=chrome-mobile&ie=UTF-8#imgrc=Lpv5G8ADWOVOZM reversed alimentation and caos polarity.
Title: Re: BMP tonestack
Post by: antonis on May 19, 2021, 01:33:40 PM
I'm not aware of any single BJT Fuzz Faxe circuit..

Could you plz verify if the layout below is the one used and modified..??

(https://i.imgur.com/BfYsqJM.png)
Title: Re: BMP tonestack
Post by: brujo on May 19, 2021, 02:01:11 PM
Yes it's this one,as the same on the First post link
Title: Re: BMP tonestack
Post by: iainpunk on May 19, 2021, 03:07:01 PM
we'd like to see a picture of the solder side of the board, and the DC voltage readings of the transistor pins.
i suspect a bad solder joint

cheers
Title: Re: BMP tonestack
Post by: Bunkey on May 19, 2021, 03:17:53 PM
Alimentation & Chaos is a freaking awesome A/B side EP title btw.

I'm calling it.
Title: Re: BMP tonestack
Post by: brujo on May 19, 2021, 04:01:28 PM
Ahaha caps ( damn autocorrector). Thanks for the help,I Will give you a photo as soon as I can. Anyway I think I Will try Also a 1uF cap for the bass section,let's lee
Title: Re: BMP tonestack
Post by: Bunkey on May 19, 2021, 04:35:20 PM
Theres a really useful program here which graphs the frequency response of various tone stacks, including the BMP, using whatever components values you want to input:

http://www.duncanamps.com/tsc/
Title: Re: BMP tonestack
Post by: antonis on May 19, 2021, 04:57:48 PM
Quote from: brujo on May 19, 2021, 04:01:28 PM
I Will try Also a 1uF cap for the bass section..

33k & 1μF for LPF set cut-off frequency at 4.8Hz..!!  :icon_wink:

You better make Bass cap 10nF or so and Treble cap 4.7nF..
Title: Re: BMP tonestack
Post by: marcelomd on May 19, 2021, 08:46:09 PM
Quote from: Bunkey on May 19, 2021, 04:35:20 PM
Theres a really useful program here which graphs the frequency response of various tone stacks, including the BMP, using whatever components values you want to input:

http://www.duncanamps.com/tsc/

Check this: https://www.guitarscience.net/tsc/info.htm (https://www.guitarscience.net/tsc/info.htm)

Made by fellow our forum fellows. Web based. More tonestacks.
Title: Re: BMP tonestack
Post by: Elektrojänis on May 20, 2021, 03:24:39 AM
If there is no sound on one end of the pot's rotation and the sound is harsh on the other end, there is probably an error in connections on the bass side filter (39k and 10nF on the original) or the pot is wired wrong.

Did you notice that the pot connections are NOT in straight order in teh layout... the middle pin of the pot goes to the lowest connection on the stripboard layout.

If the pot is connected correctly, look for bad solder joint or short around those two bass side filter components.
Title: Re: BMP tonestack
Post by: brujo on May 20, 2021, 02:43:36 PM

(https://i.postimg.cc/vxrHVgMD/IMG20210520154041.jpg) (https://postimg.cc/vxrHVgMD)

(https://i.postimg.cc/YGmStDs6/IMG20210520154059.jpg) (https://postimg.cc/YGmStDs6)

(https://i.postimg.cc/sBLXdCwf/IMG20210520154133.jpg) (https://postimg.cc/sBLXdCwf)

(https://i.postimg.cc/YjYSVVgk/IMG20210520154158.jpg) (https://postimg.cc/YjYSVVgk)
Title: Re: BMP tonestack
Post by: antonis on May 20, 2021, 03:51:12 PM
Hmmmm...  8)

(https://i.imgur.com/10HMhtJ.jpg)
Title: Re: BMP tonestack
Post by: iainpunk on May 20, 2021, 05:54:11 PM
Quote from: antonis on May 20, 2021, 03:51:12 PM
Hmmmm...  8)

[img height = 100]https://i.imgur.com/10HMhtJ.jpg[/img]
i strongly agree, but i might be prejudiced by the prediction i made earlier.

i also agree with the suggestion that the bass side of the tone stack might be the culprit.
i'd like to see a picture of the off board wiring of the potentiometer as well, that'd be great

cheers
Title: Re: BMP tonestack
Post by: antonis on May 20, 2021, 06:20:59 PM
Quote from: brujo on May 18, 2021, 05:14:12 PM
Rotating tonepot all counterclockwise completely cut off all the sound from the circuit,as you open , it start sounding,unleashing true tones and gain only in the second half of the rotation( very harsh tones)

It strongly calls for Bass shorted cap (10nF on layout).. :icon_wink: :icon_wink:
Title: Re: BMP tonestack
Post by: brujo on May 20, 2021, 09:04:58 PM
I did some trials with bass caps values and I always got full cut on all counterclock pot position. That spot looks soldered but It Is not. I will give you pot wiring as I can , and I Will try to checks solder joints again.
Thanks you all.
Title: Re: BMP tonestack
Post by: antonis on May 21, 2021, 06:41:51 AM
Quote from: brujo on May 20, 2021, 09:04:58 PM
I did some trials with bass caps values and I always got full cut on all counterclock pot position.

Try it without any Bass cap..
(of course, you'll not have Bass responce but we want to find out if full cut is due to some shorting to GND..)

Just make sure that there isn't any kind of short between cap legs pads..  :icon_wink:
Title: Re: BMP tonestack
Post by: brujo on May 21, 2021, 06:34:46 PM

(https://i.postimg.cc/PpBzQ4P3/IMG20210522003254.jpg) (https://postimg.cc/PpBzQ4P3)
Here tonepot wiring. I Will try no bass cap too,thanks again
Title: Re: BMP tonestack
Post by: iainpunk on May 21, 2021, 08:39:36 PM
is that black crocodile clamp wire a ground wire?
that would explain the silence on one side of the pot.

cheers
Title: Re: BMP tonestack
Post by: brujo on May 22, 2021, 08:03:07 AM
 :icon_mrgreen:
I feel so stupid!
Thanks man
Title: Re: BMP tonestack
Post by: iainpunk on May 22, 2021, 12:09:09 PM
Quote from: brujo on May 22, 2021, 08:03:07 AM
:icon_mrgreen:
I feel so stupid!
Thanks man
so it works now?
nice!
stuff like this happens to everyone, even to the most seasoned veteran

cheers, Iain
Title: Re: BMP tonestack
Post by: brujo on May 22, 2021, 06:25:15 PM
yes it works,sound nice and big  :icon_biggrin:
Title: Re: BMP tonestack
Post by: GibsonGM on May 23, 2021, 10:40:28 AM
Quote from: iainpunk on May 22, 2021, 12:09:09 PM
Quote from: brujo on May 22, 2021, 08:03:07 AM
:icon_mrgreen:
I feel so stupid!
Thanks man
so it works now?
nice!
stuff like this happens to everyone, even to the most seasoned veteran

cheers, Iain

Like those once in a while times, >guitar not plugged in< and so on  :)
Title: Re: BMP tonestack
Post by: Elektrojänis on May 24, 2021, 03:52:53 AM
Quote from: GibsonGM on May 23, 2021, 10:40:28 AM
Like those once in a while times, >guitar not plugged in< and so on  :)

Or volume pot on guitar at zero...

Or no power connected. I did that one at least once yesterday. And then I had a "isolated" jack on my breadboard case for connecting to an external expression pedal. It worked fine, but I wanted to reverse the way the expression pedal works. I for some reason it just worked connected one way, but not the other. Took me quite a while to notice that the hole that I had for the isolated jack was too small for it so the sleeve connection was actually shorting to ground.