Impedance buffer on Boss pedals and woolly mammoth pot types

TomA1234 · #1 07-20-2011, 08:41 AM

Hi,
I know Boss pedals have a buffered output and I am building a woolly mammoth clone.

My main bass is an active Ibanez BTB 475 but I have heard that the mammoth doesn't like active basses due to the low impedance, so I may need to use a impedance buffer.

Will a Boss pedal or two solve the low impedance and make my bass usable with the mammoth?

Also, what types are the pots in a woolly mammoth? I know the values but cant find whether each one is an A or B type pot.

Thanks.

bongomania · #2 07-20-2011, 09:15 AM

There's a mix-up in the info you're working with.

. A buffer lowers the output impedance, causing the problems with Wooly Mammoth tone. However, there is no equivalent word for a device that raises the output impedance... So pedal-users have been calling that sort of thing a "buffer" too. On the one hand it's an understandable usage since there's no better word, but otoh it leads to the sort of misunderstanding in your question.

Short version: you absolutely DO NOT want a buffer. Instead, you want a device that raises output impedance.

TomA1234 · #3 07-20-2011, 09:47 AM

OK, that's question 1 answered, put the mammoth in front of the Boss.
Thanks.

Is anyone able to give me a circuit diagram for an impedance raiser?

Jazz Ad · #4 07-20-2011, 11:19 AM

How about buying instead a pedal that
1- Doesn't sound like a hive of barfing bees (personal opinion)
2- Works just fine with active and passive basses?

It's not like the market was short of awesome fuzz pedals.

TomA1234 · #5 07-20-2011, 11:21 AM

Quote:

Originally Posted by Jazz Ad

How about buying instead a pedal that
1- Doesn't sound like a hive of barfing bees (personal opinion)
2- Works just fine with active and passive basses?

It's not like the market was short of awesome fuzz pedals.

I'm not buying it, I'm building it.
I chose the mammoth because it is easy to make and I like the sounds you can get out of it.

Jazz Ad · #6 07-20-2011, 12:41 PM

Then it would be really easy to modify the circuit so it would correct the impedance of the incoming signal.

Skrogh · #7 07-20-2011, 02:13 PM

I breadboarded one once, the schematics on the interwebs says B (liear), that's what I used, works fine.

I play an active bass too, just trow in a 100K linear pot, wired as a variable resistor between the input and the first cap. (This is similar to the push/relax on the mastotron)
Turn down the treble on your bass and the bass a bit up, that should emulate the loss of highs the low-impedance input removes from a passive bass.

TomA1234 · #8 07-20-2011, 02:32 PM

Quote:

Originally Posted by Skrogh

I breadboarded one once, the schematics on the interwebs says B (liear), that's what I used, works fine.

I play an active bass too, just trow in a 100K linear pot, wired as a variable resistor between the input and the first cap. (This is similar to the push/relax on the mastotron)
Turn down the treble on your bass and the bass a bit up, that should emulate the loss of highs the low-impedance input removes from a passive bass.

Thanks! That's saved me building another circuit!

Skrogh · #9 07-20-2011, 04:03 PM

Good luck with the building, post a pic. once you have finished

MK1 · #10 07-20-2011, 06:56 PM

Quote:

Originally Posted by Skrogh

I breadboarded one once, the schematics on the interwebs says B (liear), that's what I used, works fine.

I play an active bass too, just trow in a 100K linear pot, wired as a variable resistor between the input and the first cap. (This is similar to the push/relax on the mastotron)
Turn down the treble on your bass and the bass a bit up, that should emulate the loss of highs the low-impedance input removes from a passive bass.

Do you have a copy of the schematic by any chance? Did you make it in its own box? I just built a Fuzzy Elephant (WM Clone) and I love the way it sounds with passive basses. From what I understand though part of the "magic" of this pedal is that it does load down passive pickups. Have you had decent success doing this and using it with an active bass?

TomA, one thing you want to watch out for too is, this pedal doesn't react well to hot signals. If you give it too much signal the "wool" knob has little to no effect. I've noticed I get a lot more variation by backing the volume off a little.

kaputsport · #11 07-20-2011, 10:36 PM

Quote:

Originally Posted by Skrogh

I breadboarded one once, the schematics on the interwebs says B (liear), that's what I used, works fine.

I play an active bass too, just trow in a 100K linear pot, wired as a variable resistor between the input and the first cap. (This is similar to the push/relax on the mastotron)
Turn down the treble on your bass and the bass a bit up, that should emulate the loss of highs the low-impedance input removes from a passive bass.

Actually, the 100K liniar pot is the only difference between the Mastotron and the WM... Seriously. Without that pot, it is a WM.

Skrogh · #12 07-21-2011, 02:37 AM

@MK1:
I never boxed it up, got no use for i atm.
Instead of loading down the pickup, just turn down the treble. Loading a pickup down moves the frequency of a slightly resonant LPF down.

@kaputsport:
naah there is two more differences, there is an extra, switchable, output cap; and the transistors are different (I think they have a bit less gain in the tron)

schematic for the mastotron

BogeyBass · #13 07-21-2011, 04:23 AM

Woolly mammoth looks like a couple of common fuzz face mods that are adjustable. then a added single knob tone control.

Those mods seem cool maybe for a guitar or passive bass.

But for a active bass the good old fuzz face, with some added mods suited for active bass would actually do better.

and yah adding a zillion knobs to make a one trick pony, more "adjustable" seems cool ..but it seems you find the best settings and just leave it...so why bother hunting for pots, drilling holes and stringing more wires. just find the values and make em set resistors.

The real magic to any distortion is filtering...so yah the tone control on the woolly mammoth is a cool addition to the fuzz face ....

but really as ridiculous as it seems the most amazing fuzz tone would be a moded fuzz face circuit being followed by a 7 band EQ for good filtering....forget single knob tone control...boring

build up a fuzz face below with the mods i added in red and forget trying to build a 7 band eq...you can buy a Behringer BEQ700 for 23 bucks....bingo.. super mega homebrew graphic fuzz.

Toasted · #14 07-21-2011, 06:13 AM

I feel I am somewhat to blame for this. Apologies.

TomA1234 · #15 07-21-2011, 10:51 AM

Quote:

Originally Posted by Toasted

I feel I am somewhat to blame for this. Apologies.

Why?

Also, what kind of foot switch is used on the mammoth or doesn't it matter?

Skrogh · #16 07-21-2011, 04:23 PM

Just your standard 3PDT for true bypass and LED, I guess?

MK1 · #17 07-21-2011, 04:44 PM

Quote:

Originally Posted by TomA1234

Also, what kind of foot switch is used on the mammoth or doesn't it matter?

3PDT if you want to use an LED.

JehuJava · #18 11-27-2011, 11:57 PM

Quote:

Originally Posted by Skrogh

Turn down the treble on your bass and the bass a bit up, that should emulate the loss of highs the low-impedance input removes from a passive bass.

I was under the impression that high impedance and long cables or vintage effects removed the highs...hence the need for a buffer.

Skrogh · #19 11-28-2011, 03:32 AM

Nope. High capacitance in the cables lowers the frequency of the ICR filter. So does a load to ground (low input impedance). It's lunch time here, I'll find a paper on it after that.

JehuJava · #20 11-28-2011, 09:02 AM

I guess the way I understood it was a buffer has a high impedance input to match the bass's output impedance and a low impedance output that prevents your signal from being loaded down.

I'm no expert in the slightest, so I've been researching for some DIY pedals. I was going to build a buffer as my first "pedal" since it seems like a pretty easy first build and more useful to me than an A/B box. I appreciate learning anything new on this!