Do boosts act as a buffer?

[chuckmoose]

Does a typical boost circuit like the AMZ Mosfet Boost, SHO, or EHX LPB act as a buffer when engaged as well as boost?

[R.G.]

Practically every effects circuit acts like a buffer as compared to the guitar pickups which cause the treble loss/cable sensitivity problems.

But there is no typical boost circuit. Details matter.

[liquids]

Funny tidbit...if you read a lot of Scott Henderson stuff about gear from the below site, he swears that everything should be true bypass, because he 'hates' what buffers do to your tone.  But he also says he leaves the RC boost on (and basically all the way up) all the time....

He uses a 5 foot cable to his first pedal, etc....Only thing is, he uses a very hot RC boost as the first pedal in line.  And he really noticed the difference when it was not first in line....

http://www.online-discussion.com/ScottHenderson/viewtopic.php?t=986&highlight=buffer&sid=a2837bc2e022150650d3fe7e4c00595f
"the RC Booster sounds better when I go into it first, because the way I had it before, there was another foot of cable going through the other pedals until I got to the RC....One drawback - direct boxes have a buffer which creates a tone some guys (like me) don't like - it's fairly subtle though...I don't like buffers and don't need one since I play through a very short cable to my first pedal, and all the pedals are true bypass.

From another one...
"If you absolutely need a buffer, put it between the SD-9 and the chorus. Distortion pedals hate buffers, and I hate them too...."

So I guess he and others don't realize it that pedals like this function also as a buffer of sorts!  Since

He runs the RC all the way up, though, I suppose the difference between the all TB signal minus the buffer is not the first thing youd notice when turning it off...i.e., your more so notice it's not as loud and not as distorted anymore!

[Andi]

"If you absolutely need a buffer, put it between the SD-9 and the chorus. Distortion pedals hate buffers, and I hate them too...."

What a clueless clown. Who is he?

[liquids]

He's a 'technically' excellent guitarist, mostly known for 80's fusion type stuff (Tribal Tech) and his solo stuff....google and youtube him.  He's good, even if not your style...

[earthtonesaudio]

http://www.muzique.com/news/boosters-are-not-buffers/

[liquids]

http://www.muzique.com/news/boosters-are-not-buffers/

Awesome!  Touché!  That's why I love this forum 

[earthtonesaudio]

Really, like RG said, it depends on the details.  In my mind, buffers have 1 primary function and several secondary functions.  Primarily, they isolate the input from the output.  Secondarily, they may provide high input impedance and low output impedance.  (Most people worry more about this secondary part.)

The circuits you mentioned will work with varying degrees of success as buffers.  The SHO has high input Z (at low gains anyway) and low* output Z, but it has feedback from output to input so the isolation is not quite as good as the other two (not a noticeable thing though, just a technical aspect).
The AMZ MOSFET boost has high Zin, low Zout* and no feedback, so it isolates a little better.
The LPB has high-ish input Z (depending on model) and low* output Z, except the volume control adds output impedance as you turn it down (see muzique.com explanation about this part).

The asterisk * on the mention of low output impedance is for this reason: *a buffer with low output impedance usually also has high output current drive capability.  Basically this means that you can follow the buffer with nearly any load impedance without changing the way it reproduces sound.  With ALL the boosters the original post mentions, the circuit performance will change (volume/gain reduced) with a load on the output that approaches or is less than the value of the collector/drain resistor used.  It's one of the more intermediate/advanced subjects to learn about, but the take-home lesson is basically just that these boosts are not ideal buffers.

[liquids]

I only understand a little of the technical stuff at this point.  As someone who understands it more, can you explain what difference there might be between just a passive magnetic pickup going 25 feet into an amp through a TB pedalboard, and say, a similar TB pedal setup but with just a mini-booster on (a booster which functions poorly as a buffer, say)? 

This may be a poor example I realize, since I don't know the technical stuff, but I had a ross type clone with true bypass switching, and otherwise all TB pedals in my rig at one point.  I kept the ross on all the time for a while, but at one point, I'd keep the comp off going clean.  Suddenly when I'd turn on the ross comp, now it seemed to my ears that the comp was adding a bunch of high end, robbing low end, etc. It does to some degree, but  I was convinced that the pedal had been adding tons of high end to my signal and robbing my bass all along, so for a while I ditched it from my setup...until I started to understand buffers and starting using one...

All that be said, sometimes you run into problems when you have long cable runs and no buffers--turning off all the pedals is way different than having anything a 'cleanish' pedal on...big difference in frequency response...or, so it seems to me.

That is to say, while many boosts may not exactly be good buffers, my conclusions were that they are often a step up from just pickups on long cable runs/ big pedalboards, to my non-technical ears...and I'm interested in learning more from the technical perspective, while I may never understand, but can at least implement ignorantly.   

[chuckmoose]

Thanks for the information, this helps.  

Next question then:  (I will reread the Muzique article to see if I can figure this out for myself...)  should the buffer ideally come before the boost?  I am considering a circuit with an AMZ Mosfet boost with a fixed input high volume level and a volume knob at the output so that the boost can also go below unity gain.  Will putting a buffer before the boost solve the frequency roll-off issue as the volume is turned down?  

[Gus]

The lpb has less than 43K input resistance.  I consider > 470K higher input resistance
http://www.tonepad.com/getFile.asp?id=68

input R is (390 ohms X hfe) || 430K || 43K so it has to be less than the lowest value

It also has a gain of about 25 (10K / 390)

[R.G.]

I only understand a little of the technical stuff at this point.  As someone who understands it more, can you explain what difference there might be between just a passive magnetic pickup going 25 feet into an amp through a TB pedalboard, and say, a similar TB pedal setup but with just a mini-booster on (a booster which functions poorly as a buffer, say)? 

A passive magnetic pickup looks (to electrons) like a signal voltage generator in series with a 4K to 12K resistor and a 2H to 4H inductor. The resistance can largely be ignored, but the impedance of an inductor goes up with frequency. For instance, a 2H inductor at 7kHz is
Zl = 2*pi*f*L = 6.28*7,000*2 = 87920.  Anything which this signal drives with an impedance of around 89K will lose half the signal at 7jHz, but only 1/4 of it at 3.5kHz and only 1/8th of it at 1750Hz. So the treble gets cut out of the signal by loading. A lot.

Any pedal with an input impedance of 1M on up loses at most 1/10 of the signal at 7khz, almost unnoticeable. The mu-amp (so-called "mini-booster") usually has an impedance in this range, so it loses little treble.  Any pedal with a *constant* output impedance, even if it's high, loses all frequencies almost equally, so while there is signal loss, it's evenly distributed and just sounds quieter, not duller.

There is a second evil lurking here, as well. Capacitance. Everything electrical has capacitance. The more surface area it has, the more capacitance. Those coxial signal cables from guitar to anything else add up to 200pF of capacitance per foot. Every foot of cable between your guitar and the first buffer it hits (buffer in the generic sense, including amp inputs) loses treble twice as fast as by resistive load. So the fewer feet of cable and the higher the input resistance that a guitar drives, the less treble lost. As soon as you hit a buffer, any decent buffer (Zin>1M, Zout=10K or less and resistive) the losses effectively stop because the buffer's output prevents the selective frequency loss.

All that be said, sometimes you run into problems when you have long cable runs and no buffers--turning off all the pedals is way different than having anything a 'cleanish' pedal on...big difference in frequency response...or, so it seems to me.

Yep, long cables are bad, too, and TB lets you have very long cables.

That is to say, while many boosts may not exactly be good buffers, my conclusions were that they are often a step up from just pickups on long cable runs/ big pedalboards, to my non-technical ears.

Your ears are right.

But then it's cookbook-simple to do a good buffer.

[Paul Marossy]

Funny tidbit...if you read a lot of Scott Henderson stuff about gear from the below site, he swears that everything should be true bypass, because he 'hates' what buffers do to your tone.  But he also says he leaves the RC boost on (and basically all the way up) all the time....

He uses a 5 foot cable to his first pedal, etc....Only thing is, he uses a very hot RC boost as the first pedal in line.  And he really noticed the difference when it was not first in line....

http://www.online-discussion.com/ScottHenderson/viewtopic.php?t=986&highlight=buffer&sid=a2837bc2e022150650d3fe7e4c00595f
"the RC Booster sounds better when I go into it first, because the way I had it before, there was another foot of cable going through the other pedals until I got to the RC....One drawback - direct boxes have a buffer which creates a tone some guys (like me) don't like - it's fairly subtle though...I don't like buffers and don't need one since I play through a very short cable to my first pedal, and all the pedals are true bypass.

From another one...
"If you absolutely need a buffer, put it between the SD-9 and the chorus. Distortion pedals hate buffers, and I hate them too...."

So I guess he and others don't realize it that pedals like this function also as a buffer of sorts!  Since

He runs the RC all the way up, though, I suppose the difference between the all TB signal minus the buffer is not the first thing youd notice when turning it off...i.e., your more so notice it's not as loud and not as distorted anymore!

One thing I can say for Scott Henderson is that he knows how to get some GREAT tones, even if he might be somewhat misguided about true bypass vs. buffered whatevers. But he also uses a fairly complex rig with switching systems made by Bob Bradshaw / Custom Audio Electronics, so anything could be happening...

"If you absolutely need a buffer, put it between the SD-9 and the chorus. Distortion pedals hate buffers, and I hate them too...."

What a clueless clown. Who is he?

He's only one the greatest fusion guitar players of all time. And he is an awesome improviser, too. I love his blues stuff, totally fresh ideas with great guitar work and tones.  Here's a few examples:
Scott Henderson Blues Band "Dog Party" - http://www.youtube.com/watch?v=QG7uni9XhXk
Tribal Tech "Face First" - http://www.youtube.com/watch?v=GQeJ9X275iE
Steve Bailey's "Troglodyte's Shuffle" - http://www.youtube.com/watch?v=ZY4TVWXrOhI
Tribal Tech "Stella By Infrared High Particle Neutron Beam" - http://www.youtube.com/watch?v=Y5t3dtwHnVw

[Andi]

He's only one the greatest fusion guitar players of all time. And he is an awesome improviser, too. I love his blues stuff, totally fresh ideas with great guitar work and tones.  Here's a few examples:

Fusion sounds a bit dodgy to me, but I shall give it a go.

[Gus]

Chuckmoose
this thread and this one
http://www.diystompboxes.com/smfforum/index.php?topic=76156.0

and this

Hi Folks, I'm working on a multi boost A/B pedal for use within my bands, and maybe to be able to offer to the public if it works out well. 

from the first line in the link

Are you starting a company?

[Andi]

Burn the witch! 

[Paul Marossy]

He's only one the greatest fusion guitar players of all time. And he is an awesome improviser, too. I love his blues stuff, totally fresh ideas with great guitar work and tones.  Here's a few examples:

Fusion sounds a bit dodgy to me, but I shall give it a go.

I don't like all fusion, but I do like Scott Henderson and Allan Holdsworth quite a lot. I like some of Frank Gambale's later stuff, too. And I think Mike Miller's work with the Chick Corea Elektrik Band is outstanding.

Burn the witch! 

And which one of us is the witch?

[liquids]

There is clip of Scott on youtube doing some really creative unique stuff on a rendition of "so what" sitting down, if I recall...

Anyhow, he's very respectable, and a great player, but that was the first clip I saw that did more than impress me technically...I'll try harder to dig it up...he is really good, and crazy obsessed with his tone in ways I can't understand (he swears by one certain current production line maxon made tubescreamer-type head over heels better than all others), but far better than most of us (me at least!) on the instrument, I'd guess.     How Melodic you find him is, however, more up for interpretation...

[Andi]

And which one of us is the witch?

Twas but a lighthearted remark in response to the question on chuckmoose's intentions.

[chuckmoose]

Are you starting a company?

Company is far too big a word.  I hope to make a few gadgets for some friends and maybe some A/Bs and loopers for folks in my area (the remote mountains of Idaho) but don't expect to see my logo in Guitar Center any time soon.

Is that a problem?  I'm new here and don't know how the forum works completely.  Mostly I'm just trying to learn like everyone else.