Buffers - what do they fix/not fix? (specific example)

[mkstewartesq]

So I posted in the build forum yesterday about a seven loop switcher I built. At the end of the day, it’s basically seven true bypass 3PDTs daisychained together.

After comparing the sound of each pedal when connected to the new switcher to the sound when connected to my main switcher, all pedals are noticeably quieter on the new switcher. For example, my Boteh/Paisley drive is still distorted to some extent, but it’s not nearly as loud or lively.

Of course, my first thought was a buffer might be needed. But I know almost nothing about buffers. The standard test that I am finding for determining whether a buffer is needed when you have a lot of daisychained true bypass is to test your signal straight to the amp versus through the daisychain with all of the true bypass effects OFF (in bypass). If you hear a tone difference, a buffer is needed. When I try this test with all of the loops on my new switcher in bypass, the difference is either nonexistent or almost imperceptible. So, in an ordinary world, I would think that that means a buffer would not address the quiet pedals issue.

But, again, when you actually activate a pedal on the new switcher, it is a bit weak. Notwithstanding that all of the loops in bypass don’t seem to create a tone suck, is it still a situation for a buffer if the pedals, when activated (not in bypass), are more attenuated then when they are run off of the switcher?

If a buffer does address this kind of issue, is the issue at the input or output (i.e., should the buffer go at the input or the output (or both))? I’m actually going to build a JFET buffer today to give this a shot and try it on both the input and output to see what it does, but since this question goes more to “what problems does a buffer fix and what problems does it not fix?” I’d appreciate any input just for general edification purposes since, again, I’m completely new to buffers.

Thanks,

Mike

 

[Nostradoomus]

This is a good read, you’ll probably have luck with a buffer or two with that but experiment and see what helps!

Buffers, impedance and other internet lore

What's a buffer? What's an impedance? What's an internetz? We've all heard about the benefits of a

www.mrblackpedals.com

 

[mkstewartesq]

OK, so following up with my buffer exploration: I actually think part of the problem with my loop switcher is that I’m trying to run it off of a loop on another switcher that really relies on software relays, so that may be introducing variables I’m not even aware of.

But just to get my feet wet and start learning this stuff, I did build a buffer using the stripboard design below (fair notice, I had to sub a J201 because I didn’t have any 2N5457s). My question is, do buffers sometimes result in a slight volume drop? I haven’t noticed that with the buffer in my General Tso but I am with this rudimentary design so I’m trying to figure out which is the exception and which is the rule with respect to buffers. Any input appreciated.

Thanks as always,

Mike

 

[mdc]

A common drain circuit like that should give you close-to-but-not-quite unity gain.

 

[mdc]

Have you narrowed down the problem with your switcher to lack of a buffer?
I think I mentioned this in the other thread, but you might save yourself some time and trouble by sticking any ol' boss between your first and second switchers and see if that solves the issue.

Alternately, if you want a buffer with a bit of gain, the tillman preamp will get you there:

Discrete FET Guitar Preamp

It's basically the same as the echoplex preamp and stratoblaster.

 

[mkstewartesq]

A common drain circuit like that should give you close-to-but-not-quite unity gain.

Hey, thank you for the replies.

This sounds about right for what I’m getting, at least when run on the input of the switcher - a noticeable volume drop but not significant. For some unknown reason, when I run it on the output of the switcher (trying to consider whether I want an input or output buffer, both, or neither), it really significantly attenuates the signal (like more than 50% drop). So I’m not sure what’s going on there.

Have you narrowed down the problem with your switcher to lack of a buffer?
I think I mentioned this in the other thread, but you might save yourself some time and trouble by sticking any ol' boss between your first and second switchers and see if that solves the issue.

Alternately, if you want a buffer with a bit of gain, the tillman preamp will get you there:

Discrete FET Guitar Preamp

It's basically the same as the echoplex preamp and stratoblaster.

That’s why I posted this thread – to understand what buffers fix and what they don’t. The reason I’m thinking it’s may be more of an interplay issue between my existing switcher and the new one is that I’ve always heard buffers curing ”dull” signal. Those aren’t really my issues – if anything, the high end seems enhanced with the loss of low end and perhaps a very slight loss in signal strength. I’ve tried every permutation imaginable, including simply running the new switcher in series with the old one rather than off of a loop on the old one – but I’m still trying to make it work in that latter configuration because running in series forces me to make some really odd pedal placement choices and, besides, I won a gold medal in “beating my head against a brick wall“ in the 1996 Olympics.

I do have a buffered bypass pedal in my chain (the General Tso) so I put that in front – maybe some improvement, but slight. I also tried having a buffer in front (the Tso) and on the output (the stripboard one) but it’s hard to judge the results when the stripboard on the output is attenuating the signal so much more than it does when placed at the input (for whatever reason).

Appreciate the suggestion on the other buffer – will definitely have to look into it.

Thanks again,
Mike

 

[jwin615]

What is next in chain after the buffer(when used post switcher)?

 

[mkstewartesq]

What is next in chain after the buffer(when used post switcher)?

Actually, nothing really, at least right now. When I’m testing the loop on the main switcher where I have the new switcher plugged in, no other loops are active so it’s going straight to the cable out. However, I will also fess up and say that apparently I’m a dumbass, because the huge volume drop in that one scenario (buffer on the out) was due to a faulty patch cable. Once I swapped out the cable, volume on the buffer when using it at the input and at the output is the same.

Mike

 

[SillyOctpuss]

sorry I can't help with your problem but how do you find the quartermaster? I've been gassing for one for a while tbh. Any chance of a gut shot if it's easy to get into? I'd love to have a look at what's going on in there. I'm thinking about picking up a QMX 8 for my board.

 

[mkstewartesq]

sorry I can't help with your problem but how do you find the quartermaster? I've been gassing for one for a while tbh. Any chance of a gut shot if it's easy to get into? I'd love to have a look at what's going on in there. I'm thinking about picking up a QMX 8 for my board.

I’ll have to wait until I do some rearranging and unplugging it to try to open it (the top looks like it’s held on by maybe 10 hex bolts plus all of the hardware for the 10 foot switches so I need to undo the hardware for the switches as well) but I had to say that I really really like it. It’s my first ever switcher and I prefer simplicity - I don’t have a need for midi or programming lots of patches and presets. Which is good, because it does none of those things. Just on -off switches for each loop plus the flip-flop function that can be assigned to as many different loops as you want.

I have found the sound to be exceptionally transparent, which is why I have been probably struggling more than I need to with the switcher that I built, because the Gigrig is so good it’s kind of hard to compare with something homemade that passes the signal through seven 3PDTs and whatever signal issues that might create. I’ll be interested to see what’s inside as well because Gigrig is somewhat vague on their website and in their documentation about how it works – but I suspect it is 10 foot switches associated with circuit boards, and all switching is done electronically.

 

[Brett]

Actually, nothing really, at least right now. When I’m testing the loop on the main switcher where I have the new switcher plugged in, no other loops are active so it’s going straight to the cable out. However, I will also fess up and say that apparently I’m a dumbass, because the huge volume drop in that one scenario (buffer on the out) was due to a faulty patch cable. Once I swapped out the cable, volume on the buffer when using it at the input and at the output is the same.

Mike

If you haven’t already, try plugging your loop output cable into each loop’s output (instead of the main output) and see if you notice a difference at any point in the signal chain. Skip the buffers at this point, just to rule out any possibility that it’s something in your switcher causing the losses.

 

[SillyOctpuss]

If it's a load of hassle don't worry about it I'm just curious how they've got it setup in there. I have a few pedals which don't play well with buffers etc which I really want to keep on my board so I think a basic loop switcher will suit my needs. I've not heard anything bad about any of the gigrig stuff from anyone I know who actually has one so it's top of my list.

 

[mkstewartesq]

If you haven’t already, try plugging your loop output cable into each loop’s output (instead of the main output) and see if you notice a difference at any point in the signal chain. Skip the buffers at this point, just to rule out any possibility that it’s something in your switcher causing the losses.

Wow – what an amazing suggestion! I’ve been trying to think of a way to test each jack without disassembling the whole thing (yet again) and your idea I never occurred to me. Thank you!

In any event, I did as you suggested and tested all the outputs. They all sounded the same (good). Then I did the same thing with the inputs. Since we are basically listening to the signal in bypass I also tested it against how the main switcher sounded with this loop and switcher bypassed. The bypass signal for both was virtually identical on single notes – but I did notice when playing chords that the sound got slightly more dull and darker when the loop with the new switcher was active than when it was not - which I had not noticed until I did this test.

So it starts to look more like an issue a buffer would address. Oddly, when I flipped on the General Tso a few loops up (it’s buffered bypass so I left the effect in bypass so just the buffer was working), it did brighten up the clean signal but mathe a little too much – the sound with the Tso buffer on was brighter than the normal bypassed signal (maybe this is an expected result - again, I’m a buffer novice).

But here’s the weird thing I’m really trying to figure out since this is such a simple device (it’s literally just 7 3PDTs wired together in true bypass): when running the clean bypass signal, the volume is exactly the same when the new loop switcher is active as it is when it is inactive. But if you put a pedal on the new switcher – even just one, all by its lonesome - that pedal is both noticeably quieter than it is if you ran it directly off the main gigrig switcher and the tone is also different (more highs, less low end and body, maybe even a little “honky“). Activating a buffer doesn’t seem to do much to fix this other than to add even more high end. I’m really stumped with such a simple device why the signal in bypass maintains its volume but effects pedals seem to lose both volume and low end and sound fairly different on the new switcher than they do on the dedicated loop on the main switcher. If they just sounded a bit darker and dull (like the bypass signal does) I could understand – but that doesn’t seem to be the issue.

Again, thanks so much for the tip on testing the various jacks. At least it’s good to know that that’s not where the issue is.

Mike

 

[jwin615]

My money is on capacitance in your cables.
You're hearing the buffer do it's job.
It may sound bright/brittle because your compensating for the high end loss elsewhere.
I'm too tired to go over it but there's tons of good articles on measuring cable capacitance.
May just be one cable.
Even high quality low cap cable with poor solder joints can cause it.
Previously good cable that went bad(as you've already found one).
Happens.
I'd recommend measuring your system end to end then subtracting one cable/device at a time(take the buffer out, everything off).
Probably one of your 2 long runs.
As another experiment, take a short cable, if you have one, and plug straight into the amp with it. That's your guitars actual sound. Chase maintaining that sound.
Hope this helps.

 

[SillyOctpuss]

The extra high end is the buffer doing it's job. It's also the thing I don't like about buffers. It's basically the equivalent of plugging your guitar into your amp with a tiny patch cable, you get a load of high end that I personally don't find pleasant.

 

[music6000]

The extra high end is the buffer doing it's job. It's also the thing I don't like about buffers. It's basically the equivalent of plugging your guitar into your amp with a tiny patch cable, you get a load of high end that I personally don't find pleasant.

That's why it needs to be the first in the chain & you can compensate with the amp as if it wasn't even there.
Then take it out & you will appreciate what it's doing for your overall sound.
At home, I'm using 7 feet of cable & patch leads & 12 feet of Guitar cable, I can hear the difference without the Buffer!
My mate tried it at a Gig without his Klon & I said you aint gonna like it.
He came back 10 minutes later & said ' You were right ''
He had 15 feet of Cable from the Amp to the pedalboard, 4 feet of patch cables & another 12 feet of guitar cable.
True Bypass isn't all that its cracked up to be!!!

 

[Fama]

True Bypass isn't all that its cracked up to be!!!

AFAIK the love for true bypass came from a time when a lot of pedals had bad buffers, which colored the tone in a bad way while bypassed. Not like a good buffer (brighter), but more like muddy. So true bypass pedals were better, and stuff like that tends to stick with guitarists.

 

[SillyOctpuss]

That's why it needs to be the first in the chain & you can compensate with the amp as if it wasn't even there.
Then take it out & you will appreciate what it's doing for your overall sound.
At home, I'm using 7 feet of cable & patch leads & 12 feet of Guitar cable, I can hear the difference without the Buffer!
My mate tried it at a Gig without his Klon & I said you aint gonna like it.
He came back 10 minutes later & said ' You were right ''
He had 15 feet of Cable from the Amp to the pedalboard, 4 feet of patch cables & another 12 feet of guitar cable.
True Bypass isn't all that its cracked up to be!!!

I've gigged loads of times without a buffer. I like some of the roll off especially with strat Pickups. As soon as I turn on a pedal it's buffered anyway but having a dedicated buffer first in the chain will mess with the OCD and eternity pedals I'm currently using as my gain stages. Neither of them likes a buffer in front, if I had to use one it'd be after all of my drive pedals.

 

[mkstewartesq]

My money is on capacitance in your cables.
You're hearing the buffer do it's job.
It may sound bright/brittle because your compensating for the high end loss elsewhere.
I'm too tired to go over it but there's tons of good articles on measuring cable capacitance.
May just be one cable.
Even high quality low cap cable with poor solder joints can cause it.
Previously good cable that went bad(as you've already found one).
Happens.

Thanks. I think this is where I need to focus. If the system is fine without the switcher engaged and the sound is affected only slightly (but manageably) with the switcher on and in bypass, that seems to point to the issue with pedals sounding drastically different being somewhere in the cables that come into play when the switcher is actually active and a pedal is in play. The cables are short (less than 12 inches) (that’s what she said) and good quality (Mogami) but no way to rule out without checking that there is a soldering issue or something else going on with these cables that is more drastically affecting the tone.

Mike

 

[jwin615]

If you have some raw TS plugs, grab 2.
Engage all loops and jumper their out and in.
Put one TS in the input of the switcher.
Measure the resistance between each tip.
Then move the output plug to each out jack on the looper and remeasure.
Then move the TS jack to looper out and measure across the looper out and each loops input(return).
If you have a specific part of the loopers circuit that is resistive, this should make it apparent.

Alternatively but not as thorough, just ohm the looper master in and out and engage one loop at a time.
If you find one loop to be an issue, then perform the above on that loop to determine if it's on the send or receive side of that loop.
This is probably a better use of time. Thinking it out as I type...
If you don't have plugs handy, can pop the cover and clip onto the tip connections.
Wouldn't hurt to check capacitance, if your meter has good enough specs to measure that low. I doubt you'll have any in the looper itself but maybe in a cable?
Would be more concerned with your longer cable runs in that regard.
Would be interested in your total system capacitance, end to end.