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AMZ Super Buffer

Started by blooze_man, May 20, 2010, 05:13:06 AM

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blooze_man

May 20, 2010, 05:13:06 AM
I just finished building the AMZ Super Buffer and A/B'd it in and out of my pedalboard. With it on, my signal actually darkens a little bit with some slight volume loss. I used Jack Orman's PCB design for it and the only part I had to sub were the 2.2M resistors for 1M. Is it vital they be 2.2M? or maybe I just don't need the buffer...
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GibsonGM

#1
May 20, 2010, 07:27:47 AM
No, those are just pulldown resistors and should just be 1M or greater.  Higher values will increase hiss a little, no big deal. 
I'm surprised that it would darken your signal - seems like it should actually brighten it up a little? 
Are you using the required opamps, and .1uF caps? 
How about those paralleled .1 and 10uF caps at the output? Have you tried other opamps?

In general, buffers should = brighter, because they are eliminating the action of parasitic capacitances at device inputs, which shunt high frequencies to ground. I haven't used this particular one, but I suspect that maybe there is a wiring or parts substitution error somewhere?
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knealebrown

#2
May 20, 2010, 07:40:58 AM
Having built this only afew weeks ago i can +1 that it should make your signal slightly brighter if nothing else. Can you tell us your set up?
''99 problems but a glitch aint one!''

blooze_man

#3
May 20, 2010, 03:39:16 PM
I have 3 boss pedals, 4 homemade true bypass pedals, and a behringer. As far as I know, everything I did was correct cause I used the pcb made by the creator of the circuit. I know that boss pedals have a decent buffer in them already but I still find it strange what mine is doing.
Big Muff, Trotsky Drive, Little Angel, Valvecaster, Whisker Biscuit, Smash Drive, Green Ringer, Fuzz Face, Rangemaster, LPB1, Bazz Fuss/Buzz Box, Radioshack Fuzz, Blue Box, Fuzzrite, Tonepad Wah, EH Pulsar, NPN Tonebender, Torn's Peaker...

rockhorst

#4
May 21, 2010, 06:50:12 AM
How about just guitar -> buffer -> amp? Still darkening the tone?
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blooze_man

#5
May 21, 2010, 06:33:36 PM
Yeah it still darkens it even if it's the only thing in the signal path
Big Muff, Trotsky Drive, Little Angel, Valvecaster, Whisker Biscuit, Smash Drive, Green Ringer, Fuzz Face, Rangemaster, LPB1, Bazz Fuss/Buzz Box, Radioshack Fuzz, Blue Box, Fuzzrite, Tonepad Wah, EH Pulsar, NPN Tonebender, Torn's Peaker...

roseblood11

#6
October 15, 2010, 07:39:19 PM
If you decrease all three 2.2M resistors to 1M, the input impedance of the circuit is 500k. Not a good idea...

therecordingart

#7
October 15, 2010, 09:18:28 PM Last Edit: October 15, 2010, 09:21:03 PM by therecordingart
Quote from: roseblood11 on October 15, 2010, 07:39:19 PM
If you decrease all three 2.2M resistors to 1M, the input impedance of the circuit is 500k. Not a good idea...

Doing a really rough load loss calculation....

If the guitar has a 15k impedance and the buffer has a 500k impedance that is a signal loss of roughly .26db and only .17db if you double the circuit impedance...not a big deal. In general if the load has an impedance about 10x that of the source you are good to go. I'm a noob so I can be really wrong, but I'm only chiming in to verify whether I'm right or not.
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