Comments on: Boosters Are Not Buffers

By: admin

admin — Tue, 13 Oct 2009 23:31:41 +0000

>>>Would the Zvex SHO make a good buffer?<<<

Lots of people use it for that purpose with good results. The output impedance is around 5k which is a bit high for my liking though.

By: Big M

Big M — Tue, 13 Oct 2009 16:59:43 +0000

Would the Zvex SHO make a good buffer?

By: chuck

chuck — Sat, 13 Jun 2009 23:11:32 +0000

couldn’t a small cap across lugs 3 and 2 of an out-pot help “fake fix” the loss of highs and allow them to pass?

similar to a bleed mod to a guitar’s volume pot.

Please tell me if that’d work, I’m just curious…

By: Nicholas Maris

Nicholas Maris — Thu, 23 Apr 2009 14:59:05 +0000

Hi Jack,
Great website, been visiting it for a while, some truly good work going on… FYI, as I recall, Craig Anderton codified a set of basic pedal design requirements back when he was doing his GP column and it was also summarized in EPFM (darn it, I’ve misplaced my copy), but the concept has stayed with me, so when I design a pedal it conforms to his basic requirements of hign Zin (I think his min value was 100k) and low Zout (I think his was 100 ohms max or thereabouts). Sometimes it pays to add an emitter follower or source follower output stage. If I can do a loading estimate I basically try to follow a “maximum 10%” rule of thumb so that the attenuation caused by loading is no more than 10% (or -20dB, whatever). Keep up the good work and enjoy your new lab! – Nicholas

By: admin

admin — Wed, 01 Apr 2009 11:38:48 +0000

Thanks for your comments… the inductance and capacitance of the connecting cable can certainly introduce additional changes in the frequency response that can be avoided by have a buffered volume control, or a low impedance output as with the AMZ Mosfet Booster.

By: Alex

Alex — Mon, 30 Mar 2009 13:47:41 +0000

Thanks for doing the article, Jack. The subject seems to come up quite often on internet forums.

The issue becomes even more complex when you model the cable as a series of L-C filters rather than a single capacitance. This gives a frequency response that may just be a simple 6dB roll-off, or a resonant peak followed by a much steeper roll-off, depending on how the cable is terminated.