Buffer preamp AKA Unity Gain Buffer

[eyeprod]

I saw a layout for a small onboard preamp and I decided to build it and put it in one of my electrics just before the output jack. It took maybe an hour to build and mount (uses a 9v battery btw) I expected to notice a bit of a difference since I've been using a lot of pedals lately and these things evidently are helpful in some situations where you have a chain of all true bypass pedals. I wired it to a switch, so I could A/B it, so to speak, and I've read that some transistor based effects don't groove with a buffer like this.

Anyway, it has completely blown me away. The tonal quality is utterly amazing now. Switching it off is like putting a blanket over your speakers. The headroom is incredible and wow if it doesn't kick every pedal I've thrown at it up a notch or two. Some fuzzes I didn't care for before are now somehow needing to find a space on my board. Wahs... holy shit. I built a coloursound wah into a crybaby enclosure recently and that thing was rad before, but now, it's unbelievable. An old boomerang wah I have wouldn't play well with other pedals, but with this buffer on it's game for anything, any pedal order, whatever.

I cannot recommend this simple and cheap mod enough to a tone freak. Yeah, you have to fit a 9v into your guitar and change out the jack to a stereo one and wire it so it turns off the battery when you unplug the guitar, but it's well worth it. I'm putting one of these into my bass next. Can't wait. You can easily put something like this into a small pedal enclosure, but it's not the kind of thing that you need a footswitch for because you just leave it on.

Oh btw, this one I built is a clone of what was inside some of jerry garcias guitars. Basically it's designed to deal with long cables onstage. Check it out. This is a stripboard layout, so really easy to build with few parts. There are lots of other small booster/preamp/buffer circuits out there, so you're certainly not limited to this particular circuit, but seriously, try this.



http://tagboardeffects.blogspot.com/2014/04/jerry-garcia-tiger-preamp.html
http://tagboardeffects.blogspot.com/search/label/Buffer

[spookstrickland]

How about building it into a pedal and just running it first in the chain?  I wonder if the Klon buffer is similar to this one.

Cool beans though, a buffer can really wake up your tone.

[jibberish]

ya buffers are awesome. there are several different designs, but if jerry approved, it works for me. thx for links and info

you can use buffers as impedance changers. I/O impedance matching or mismatching affects tones a great deal.

my high end NIKKO pre-amp has impedance adjustments for the TURNTABLE INPUT(tt cart is excited coil of wire just like a guitar pup)
my hi end cassette deck has recording bias adjustments for fine tuning to the physical tape particle makeup
SO, the hi end shit all has fine tuning for those multi mfr multi impedance sources.


SO, next iteration, why not try some different I/O impedances, or adjustable with a pot or rotary switch resistor cascade etc. for super tone tweaking.

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is there room inside the tuner pedal to add in that buffer circuit? remember you can rebuild the circuit in a different shape to fit, then scavenge from the tuner's power supply.  add a new on/off switch with true bypass(imitate 1/4 jack insert switch effect) for the buffer circuit


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edit: I just remembered I already have one of these 9v guitar buffer setups installed in my one schecter by EMG. custom 9v battery housing, unplugged=unpowered 1/4" jack installed already [little girl snickering pic goes here..too lazy to find it]

more edit: if that is always on, you cant run straight in to a tube amp. pup coil->tube input = ultimate tube amp setup.  no silicon based wave filtering in between.

[eyeprod]

Yeah I have yet to plug in to a tube amp but I expect good things. Have been into my ss amps lately. Love the convenience and they sound great for what I'm doing.

Some switching like you described jib, seems handy for certain situations. I'm going to wire this up so it's always on. I read that it's the same basic thing that emg offers. Spook, there's a layout for the klon buffer at the link I posted. Yeah y ou can mount these in a pedal but it seems like a waste of space and one extra thing to require a  pow erjack and a patch cord.  Bet ter to just put it inside something else and tap into the 9v that way.

[spookstrickland]

Yeah I have yet to plug in to a tube amp but I expect good things. Have been into my ss amps lately. Love the convenience and they sound great for what I'm doing.

Some switching like you described jib, seems handy for certain situations. I'm going to wire this up so it's always on. I read that it's the same basic thing that emg offers. Spook, there's a layout for the klon buffer at the link I posted. Yeah y ou can mount these in a pedal but it seems like a waste of space and one extra thing to require a  pow erjack and a patch cord.  Bet ter to just put it inside something else and tap into the 9v that way.

I have a hard time reading those tag board layouts, I prefer a schematic.  I was just wondering was the Klon close to Jerry's design?  everybody raves about the klon it would be funny if he just coppied Jerry.

I've been thinking about building a fuzz into my guitar again.  It would be great for traveling with just plug into what ever amp is there and just wail!

You should post some videos.  I'd like to hear and see this.

[eyeprod]

The klon and other IC based buffers are very similar.

I know, it's hard to look at those layouts and determine the signal path. They're great for easy assembly tho!

[jibberish]

if you study enough of these line level doo dads, you will see a pattern:

everything has resistors and possibly a filter cap on input to set impedance and filter if necessary

the OP amp, or 2 transistor amp model get biased and powered.

a buffer has a gain of 1. otherwise it is like any other amp. buffers are impedance matchers, not gain amplifiers.

output once again has resistors to set the output impedance and maybe a cap for filtering

all these circuits use personal circuit design tweaks for tweaking the performance by the designers. some have worked out cleaner or more musical than others. probably like everything else, you would have to audition several and see what you can hear.

[moose23]

If you're going to put this buffer in a bass you may want to increase the 22nF cap at the input to around 100nF. The high input impedance from the two 1m resistors used to bias the opamp is what's giving you all that extra life and high end. The Super Hard On boost does a similar thing.

[eyeprod]

yeah, I was thinking that it might need a cap mod to be appropriate for bass. Good point.

I tried this buffered guitar into my v4 and it was a bit brighter, but didn't quite come alive the way my ss amps did. Interesting. Maybe at higher volume it would be more awesome.

[moose23]

Pretty sure tube and solid sate input impedance will be different which may explain it.

[spookstrickland]

Pretty sure tube and solid sate input impedance will be different which may explain it.

Ya I think tube input impedance is much higher.

[dunwichamps]

Assuming the input of a tube amp is not being driven into grid conduction then the input impedance at say 1 kHz is determined solely by the input grid leak resistor which is normally around 1M. The actual input impedance is going to vary across the frequency spectrum and at higher frequencies it will be much lower due to miller capacitance from the first gain stage.

[VOLVO)))]

All those fuckin college words! Hi Nick!

[dunwichamps]

All those fuckin college words! Hi Nick!

miss ya kid

[VOLVO)))]

Yeah, Facebook killed my soul, call me sometime.

[eyeprod]

Thanks for chiming in. I still have not put this in my bass, but still digging on guitar.