Zvex - Box of Rock  [traced]

General documentation, gut shot, schematic links, ongoing circuit tracing, deep thoughts ... all about boutique stompboxes.

Re: Zvex - Box of Rock

Postby sevinisthenumber » 02 May 2009, 19:09

mrhenry wrote:hey sevinisthenumber,

the led for the diode should be fine. the diodes in the BOR are for static protection and polarity protection. as far as the tantalum cap, it depends. certainly there is no problem with the medium (tantalum) but the value has been changed if its the C8 that is part of the double low-pass filter that cuts the highs at the end of the circuit. it calls for a value of 2n, if you change the nature of the filter it will probably change the output frequency... but that isn't a bad thing.

also, as far as getting more gain, i would recommend increasing the gain of the each mosfet stage following the first and then, if you still need more gain, just add clipping diodes at the end. silicone diodes will give you a more metal-ish plexi sound with the tone control cranked.

in any case just a thought.

hope that helps.

-mrhenry


On my madbean layout c8 is a 1uf. Correct?

How do i increase the gain of each gain stage?
Where would the "end be" to add clipping diodes?
"The man who says he knows everything will never know the truth"
C.S. Lewis
User avatar
sevinisthenumber
Cap Cooler
 
Posts: 455
Joined: 26 Dec 2008, 02:42
Has thanked: 0 time
Have thanks: 30 times

Re: Zvex - Box of Rock

Postby mrhenry » 02 May 2009, 19:52

i guess i was looking at the wrong layout (im referring to the one on page 15 of this discussion). in any case, lots of people claim that tantalum sounds better if its a cap in the signal path-- so go with it.

as for the gain questions, looking at the schematic, it seems that if you reduce the resistance on the drain of the mosfet, then it will set the gain to maximum... i think that is how it works. so, you could boost up those two stages. But i am willing to bet you will get a lot of woofy bass characteristics and some noise if they are all maxed out all the way.

It might be better just to, well, add some more gain stages: just add in more mostfet stages like the ones that are already there. or you could add a second gain control as well by having third or fourth stage that is adjustable with a potentiometer like in the first stage. you could do whatever you want really. but you will get more noise probably-- hence the BOX OF METAL has a noise reducer/limiter thing in it.

if you want to add diodes, I would do so after the tone control and before the filter network (10k/2n). that way the diodes will clip to the maximum extent and then they will get smoothed out by the filter. for a nasty sound try run of the mill silicone diodes that come in a 100 pack at radio shack for like 2 bucks. or you can get fancy with red leds (or green or whatever) you can also put darlington transistors there... all that boutiquey kind of thing. really you should just feel free to try stuff... if you don't like it then you can easily change it.

-mrhenry
mrhenry
Breadboard Brother
 
Posts: 73
Joined: 06 Feb 2008, 16:42
Location: Ft. Worth, Texas
Has thanked: 0 time
Have thanks: 0 time

Re: Zvex - Box of Rock

Postby cpm » 03 May 2009, 00:33

the 9v zener is used to protect, by conducting (reverse) for voltages larger that 9v. Any other diode or led will have a reverse brakdown voltage larger than 9v, may be 50v or more, so an led wont protect against voltages that may fry your mosfet
User avatar
cpm
Resistor Ronker
 
Posts: 277
Joined: 29 Oct 2008, 10:55
Location: spain
Has thanked: 0 time
Have thanks: 51 times

Re: Zvex - Box of Rock

Postby sevinisthenumber » 03 May 2009, 03:00

cpm wrote:the 9v zener is used to protect, by conducting (reverse) for voltages larger that 9v. Any other diode or led will have a reverse brakdown voltage larger than 9v, may be 50v or more, so an led wont protect against voltages that may fry your mosfet


thanks for that info.

what are some diodes that will work? Will a 1n400x work?
"The man who says he knows everything will never know the truth"
C.S. Lewis
User avatar
sevinisthenumber
Cap Cooler
 
Posts: 455
Joined: 26 Dec 2008, 02:42
Has thanked: 0 time
Have thanks: 30 times

Re: Zvex - Box of Rock

Postby Fuzzer » 03 May 2009, 04:02

cpm wrote:Any other diode or led will have a reverse brakdown voltage larger than 9v, may be 50v or more, so an led wont protect against voltages that may fry your mosfet


Hmm, I don't know if the reverse voltage is that high, my understanding was that RED LEDs were good for like 5 to 12 volts.

However, your best choice is to go with the Zener diode because you can be sure of the reverse voltage you're protecting the circuit from.
The Freestompboxes Forum search function is soo great, use the search function..., the S E A R C H function.
User avatar
Fuzzer
Transistor Tuner
 
Posts: 1037
Joined: 16 Sep 2007, 16:17
Has thanked: 0 time
Have thanks: 19 times

Re: Zvex - Box of Rock

Postby sevinisthenumber » 07 May 2009, 06:03

I wanna try what mr henry said and add some clipping diodes to the circuit. I wanna put this on a switch so I can have the stock and then with diodes.
Can someone explain where to do this in the circuit? I know that two diodes facing opposite directions will go to ground, but from where?? I'm using mad beans layout.
"The man who says he knows everything will never know the truth"
C.S. Lewis
User avatar
sevinisthenumber
Cap Cooler
 
Posts: 455
Joined: 26 Dec 2008, 02:42
Has thanked: 0 time
Have thanks: 30 times

Re: Zvex - Box of Rock

Postby sevinisthenumber » 18 May 2009, 21:54

anybody?

What about an additional tone control to roll of the high frequency.
"The man who says he knows everything will never know the truth"
C.S. Lewis
User avatar
sevinisthenumber
Cap Cooler
 
Posts: 455
Joined: 26 Dec 2008, 02:42
Has thanked: 0 time
Have thanks: 30 times

Re: Zvex - Box of Rock

Postby UZILSD » 18 May 2009, 22:33

sevinisthenumber wrote:I wanna try what mr henry said and add some clipping diodes to the circuit. I wanna put this on a switch so I can have the stock and then with diodes.
Can someone explain where to do this in the circuit? I know that two diodes facing opposite directions will go to ground, but from where?? I'm using mad beans layout.



Put them just after C5, on the tone stack side, and go to ground. In the tone stack the signal is biased to ground so it will clip the right way.

For the highs rolloff, you could put a pot instead of one of the 10k resistors after the tone stack (try 50k or 100k). For more dramatic effect use a dual gang pot and substitute both. It should work.
UZILSD
Breadboard Brother
 
Posts: 98
Joined: 23 Mar 2009, 22:40
Has thanked: 0 time
Have thanks: 1 time

Re: Zvex - Box of Rock

Postby sevinisthenumber » 19 May 2009, 07:04

UZILSD wrote:
sevinisthenumber wrote:
For the highs rolloff, you could put a pot instead of one of the 10k resistors after the tone stack (try 50k or 100k). For more dramatic effect use a dual gang pot and substitute both. It should work.

DO you mean 10MEG resistor?
"The man who says he knows everything will never know the truth"
C.S. Lewis
User avatar
sevinisthenumber
Cap Cooler
 
Posts: 455
Joined: 26 Dec 2008, 02:42
Has thanked: 0 time
Have thanks: 30 times

Re: Zvex - Box of Rock

Postby UZILSD » 19 May 2009, 11:12

sevinisthenumber wrote:
UZILSD wrote:
sevinisthenumber wrote:
For the highs rolloff, you could put a pot instead of one of the 10k resistors after the tone stack (try 50k or 100k). For more dramatic effect use a dual gang pot and substitute both. It should work.

DO you mean 10MEG resistor?


No, I mean R16 and R17 on MadBean schematic (the Krankosaurus). They form a low pass filter along with C8 and C9. I haven't tried it but it should work.
UZILSD
Breadboard Brother
 
Posts: 98
Joined: 23 Mar 2009, 22:40
Has thanked: 0 time
Have thanks: 1 time

Re: Zvex - Box of Rock

Postby madbean » 19 May 2009, 13:52

Might be easier just to remove one resistor/cap network and make it into a first order filter. Or use a switch to lift the cap. That would add in a bit more high end above 8k or so. As it is, it's rolling off 12db per octave starting around there.
madbean
 

Re: Zvex - Box of Rock

Postby UZILSD » 19 May 2009, 14:24

madbean wrote:Might be easier just to remove one resistor/cap network and make it into a first order filter. Or use a switch to lift the cap. That would add in a bit more high end above 8k or so. As it is, it's rolling off 12db per octave starting around there.


I didn't realize if he wanted more highs or less highs, I understood he wanted less.

What are you looking for, sevinisthenumber?

Adding a pot you should be able to control the cutoff point in either direction anyway, the problem is to find space on the enclosure for another knob! :D

If you just wont more high end do what madbean said.
UZILSD
Breadboard Brother
 
Posts: 98
Joined: 23 Mar 2009, 22:40
Has thanked: 0 time
Have thanks: 1 time

Re: Zvex - Box of Rock

Postby sevinisthenumber » 19 May 2009, 15:42

the circuit is so large an extra pot may be pushing it! ha!

i want to be able to roll some sparkle off. the pot may work well?
"The man who says he knows everything will never know the truth"
C.S. Lewis
User avatar
sevinisthenumber
Cap Cooler
 
Posts: 455
Joined: 26 Dec 2008, 02:42
Has thanked: 0 time
Have thanks: 30 times

Re: Zvex - Box of Rock

Postby UZILSD » 19 May 2009, 22:59

sevinisthenumber wrote:the circuit is so large an extra pot may be pushing it! ha!

i want to be able to roll some sparkle off. the pot may work well?


Yes, it should work. Replace one of those resistor with a 50K or 100K pot. You will get a 6dB per octave low pass filter of witch you can control the cutoff frequency. If you want more effect, use a dual pot and replace both, you will have a 12dB per octave low pass. Just try and let us know!
UZILSD
Breadboard Brother
 
Posts: 98
Joined: 23 Mar 2009, 22:40
Has thanked: 0 time
Have thanks: 1 time

Re: Zvex - Box of Rock

Postby GJonesy » 23 May 2009, 00:37

ciccius wrote:Hi everybody

I trie ti build the Krankosaurus (bor of madbean) but not work. I built this pedal two time and all time not work. Anybody can help me? How I can debug this pedal?

Bye


Ive built mine up using madbeans pcb and it worked first time. Not really sure where to start. is it getting power? have you got the BS170s in the right way round?
I just want to thank madbean for his great work not just on the BOR but on his other pcbs too. Ive bought a number of them from him and Im just finishing off the last few now. Much respect to madbean!
GJonesy
 
Posts: 30
Joined: 26 Jan 2009, 17:01
Location: UK
Has thanked: 7 times
Have thanks: 1 time

Re: Zvex - Box of Rock

Postby sliberty » 23 May 2009, 02:50

ciccius wrote:Hi everybody

I trie ti build the Krankosaurus (bor of madbean) but not work. I built this pedal two time and all time not work. Anybody can help me? How I can debug this pedal?

Bye


"Help, it doesn't work" is not really enough information for us to begin to help you. If you are not really familiar with electronics, you should put up some pictures, and maybe we'll see a problem. If you are familiar with electronics, then you'll need to tell us more. For example, what testing have you done? Have you measured voltages? Have you probed with an audio probe? I am sure we would all love to help you, but we aren't mind readers.
sliberty
 
Posts: 33
Joined: 22 Feb 2008, 20:16
Has thanked: 0 time
Have thanks: 1 time

Re: Zvex - Box of Rock

Postby Scruffie » 23 May 2009, 22:31

Yea the Crackle is normal, the same as how the Zvex Super Hard On says Crackle Okay on it, this is based off it so has the same 'issue'
Scruffie
Opamp Operator
 
Posts: 1739
Joined: 13 Mar 2009, 18:59
Location: London.. ish, Uk
Has thanked: 27 times
Have thanks: 139 times

Re: Zvex - Box of Rock

Postby sevinisthenumber » 04 Jun 2009, 06:17

UZILSD wrote:
sevinisthenumber wrote:the circuit is so large an extra pot may be pushing it! ha!

i want to be able to roll some sparkle off. the pot may work well?


Yes, it should work. Replace one of those resistor with a 50K or 100K pot. You will get a 6dB per octave low pass filter of witch you can control the cutoff frequency. If you want more effect, use a dual pot and replace both, you will have a 12dB per octave low pass. Just try and let us know!


Sorry for the long delay... Been outa town..

I put a 50k pot in place of r16 and its awesome... Its like a presence control of sorts... very useful on my twin and it reacts well with the tone knob so you can find that balance of keeping the tone snappy but not piercing!!!!

Thanks for the help guys!!!!
"The man who says he knows everything will never know the truth"
C.S. Lewis
User avatar
sevinisthenumber
Cap Cooler
 
Posts: 455
Joined: 26 Dec 2008, 02:42
Has thanked: 0 time
Have thanks: 30 times

Re: Zvex - Box of Rock

Postby UZILSD » 04 Jun 2009, 09:29

Sorry for the long delay... Been outa town..

I put a 50k pot in place of r16 and its awesome... Its like a presence control of sorts... very useful on my twin and it reacts well with the tone knob so you can find that balance of keeping the tone snappy but not piercing!!!!

Thanks for the help guys!!!!


You're welcome! I'm glad you liked this mod... maybe I'll add it to my BOR too, when I'll overcome my usual lazyness about drilling enclosures! :mrgreen:
UZILSD
Breadboard Brother
 
Posts: 98
Joined: 23 Mar 2009, 22:40
Has thanked: 0 time
Have thanks: 1 time

Re: Zvex - Box of Rock

Postby kurtlives » 14 Jul 2009, 18:18

Been meaning to build this one for a long time and finally getting around to it...

Did anyone save a copy of Torchy's vero layout before he pulled them?
kurtlives
Solder Soldier
 
Posts: 175
Joined: 20 Jan 2008, 03:18
Location: Toronto, Canada.
Has thanked: 0 time
Have thanks: 5 times

PreviousNext

Return to Boutique Stompboxes dissected...

Who is online

Users browsing this forum: cniers13 and 19 guests