I just boarded the AMZ Super Buffer - just need to throw together a quick one for my personal pedal board, and I really like the idea behind it.
I followed the "official" schematic (http://www.muzique.com/lab/superbuff.htm (http://www.muzique.com/lab/superbuff.htm)), experimented a bit with Op-Amps and settled for a pair of OPA2134s, because I have quite a few.
What all variants have in common (I tried what i had around, TL072, 5532, some ridiculously expensive TI-chips, but I guess Op-Amps don't really contribute an awful lot to this): In direct comparison [guitar->short cable->(excellent) tube amp] and [guitar->short cable->Super Buffer->short cable->said tube amp[ the buffer variant audibly cuts the bass/low mid content of the signal.
I checked my breadboarding against the schematic several times - no mistake here.
Then i changed the input cap to 220n, just for the heck of it, to no real avail.
Can I add/subtract something to/from the thing to have a real flat response?
are you married to the idea of using this circuit? i made threw their mosfet buffer into a volume pedal that want working and it sounds GREAT on my bass (i use it last in the chain before a DI... even my non-musician better half noticed a difference without me prompting her)
i realize that this doesn't at all answer your question but i am really big on simplicity/as low parts count as possible
I'm not absolutely committed to ANY circuit :) Just wanted to try this one out. Tampered with quite a few other buffers in the past - each one unique in his way like the Super Buffer. Just wanted to know what could "suck" the bass content out of the signal ...
Is it sucking bass, or are you just not losing as much treble?
It's probably the very high input Z of that circuit causing the perception of losing bass. You could TRY a much much larger input cap, see if that helps...but yeah, for basic buffering, the more simple buffers will certainly more than do the trick!
I am surprised anyone would suggest a 5532 for this circuit. It has very good voltage noise performance but its current noise is sufficiently high that one device would be best suited for a source with a 20,000 ohm output impedance. Four of them in parallel would be best with a 5000 ohm input. A single op amp would do the job if it was FET-input for high input impedance.
The turnover frequency is about 0.7 Hz at the input. The output has the same turnover for an infinite input impedance of the next stage but the output capacitor is where you could expect a problem because you are not able to designate a minimum impedance for pedals like a Fuzz Face or a Wah. The lower this impedance, the higher the turnover.
I think the 5532-based buffer makes the most sense at the end of the signal chin to drive a long cable to the amp--that massive drive capability is really what the 5532 brings to the table, as Jack says in the article (although I imagine one 5534 should be plenty, a paralleled 5532 more than enough, two 5532s major overkill). If your buffer is going to be the first thing the guitar sees, a higher Z-in (like the discrete FET buffers or an FET-input op amp) may make more sense. RG Keen designed a hybrid FET-BJT buffer that checks off both boxes (high Z-in, low Z-out) nicely, and may suit your purpose.
In any case, I can't imagine where you would be losing lows with the Super Buffer.
What Matt & sir Mike said..
Quote from: KarenColumbo on October 02, 2019, 11:38:30 AM
Can I add/subtract something to/from the thing to have a real flat response?
If you insist on
perception of bass loss, you probably need a bass booster.. :icon_wink:
This thing surprises me. A buffer like this shouldn't cut bass frequencies, at least not so enough. I built the simple opamp Buffer using TL071 or the buffer in the Klon Centaur I built, wihtout any problem, used with guitars.
I think thet the input impedance of the SUper Buffer is determinate from R5 and R6 in the schematic in the page of Musique linked above. The two resistors are 2.2M and the input impedence should be 1.1M, with a guitar pickup shouldn't cut bass, I'm not sure about a bass guitar, but I say that project must work ok just like this.
Quote from: Elijah-Baley on October 03, 2019, 08:35:16 AM
I think thet the input impedance of the SUper Buffer is determinate from R5 and R6 in the schematic in the page of Musique linked above. The two resistors are 2.2M and the input impedence should be 1.1M, with a guitar pickup shouldn't cut bass, I'm not sure about a bass guitar, but I say that project must work ok just like this.
Not presicely..
(there are actually 2 HPFs, one R6/C1 and another one R5/Cwhatewer_previous_effect_out_cap
But yes.. It shouldn't "cut" any bass for frequencies of interest.. :icon_wink: