Buffers before or after Overdrive Pedals?

[saxxamafone]

This is probably not the most scientifically accurate example but I kinda think of it like this.

Imagine you are blowing into a straw while holding it between your index and thumb fingers. Your mouth (the guitar pickups) can blow at a certain pressure from 0 - 10 through the straw. Your fingers holding the straw pick up how much pressure they feel and pass the signal along for highs and low on a scale from 0 - 10. 0 being max lows, 10 max highs.

If you use a small straw that provides enough resistance to your lung capacity, your fingers holding the straw can pick up the full pressure range as it expands and contracts. If you use a lower resistance (impedance), large wrapping paper tube and blow into it with the same force your fingers may only see a range of pressures from 0 - 8 as you're not able to provide enough force to expand it fully with your lungs.

So matching the impedance initially to the guitar pickups passes that full 0 - 10 range along like the small straw from the get go, much like a game of telephone.

Lets say you have only one buffer and put it after your od. Because you had not placed a buffer before it, the top value the od sees going into it is capped at an 8, but because it has lots of cabling after it the max out of the amp winds up being a 6. - the treble is rolled off.

The buffer after the od would allow it to pass an 8 to the amp so it would still be brighter than without it (a 6), but not quite as bright as it could be (a 10) if you had also loaded the pickups with a proper buffer from the start.

Great info. Interesting my test showed this:

Buffer -> OD -> Amp = brighter

OD -> Buffer -> Amp = not quite as bright

 

[Faded Abyss]

This is probably not the most scientifically accurate example but I kinda think of it like this.

Imagine you are blowing into a straw while holding it between your index and thumb fingers. Your mouth (the guitar pickups) can blow at a certain pressure from 0 - 10 through the straw. Your fingers holding the straw pick up how much pressure they feel and pass the signal along for highs and low on a scale from 0 - 10. 0 being max lows, 10 max highs.

If you use a small straw that provides enough resistance to your lung capacity, your fingers holding the straw can pick up the full pressure range as it expands and contracts. If you use a lower resistance (impedance), large wrapping paper tube and blow into it with the same force your fingers may only see a range of pressures from 0 - 8 as you're not able to provide enough force to expand it fully with your lungs.

So matching the impedance initially to the guitar pickups passes that full 0 - 10 range along like the small straw from the get go, much like a game of telephone.

Lets say you have only one buffer and put it after your od. Because you had not placed a buffer before it, the top value the od sees going into it is capped at an 8, but because it has lots of cabling after it the max out of the amp winds up being a 6. - the treble is rolled off.

The buffer after the od would allow it to pass an 8 to the amp so it would still be brighter than without it (a 6), but not quite as bright as it could be (a 10) if you had also loaded the pickups with a proper buffer from the start.

Awesome analogy! Another good one that REALLY helped me understand after many years of confusion (I work with electricity for a living but not this kind). When I say “pickup loading” means that pickups are connected directly to it (first device in chain that is either activated or always activated in a buffer context)

1 meg-ohm example pickup loading: You have a water bottle. You poke a small hole in the cap and squeeze the water bottle. The water will have a steady stream even if you adjust or change how hard you squeeze it - this is higher impedance, proper loading of pickups.

5,000 - 50,000 ohm example pickup loading example: You have a water bottle only this time you remove the cap. Hold that thing upside down and without squeezing the water is going to glug glug and have in inconsistent stream kind of like when you had kidney stones because you were drinking 4 rockstars and refills a day - this is too low impedance but gives desirable characteristics when you want that sludgy filthy fuzz tone.

Vintage fuzz tones will have that low impedance but newer fuzz pedals don’t because: Ideally, audio devices input impedance will be at least 10 times higher than the output device feeding (or before) it.

I believe pedals usually have around 10k ohm output impedance so 100k or higher is needed to meet the criteria. This is why companies will often say about their fuzz pedals: “plays nice with other pedals” or “works after buffers”. This mindset is outdated marketing claims similar to saying that a pedal having “true bypass” is a standout feature

 

[tjnx]

Great info. Interesting my test showed this:

Buffer -> OD -> Amp = brighter

OD -> Buffer -> Amp = not quite as bright

That means that the roll off from the pickups' mismatched load was greater than whatever came after the od, so you found the right spot!

Why do some people swear by putting it at the end then?
Imagine you had the worlds worst cable after the od, to the amp, and only 1 buffer to use. This could a good time to put the buffer last.

Lets say after the od, the 'straw' (crappy cable) it sees is double the diameter what it should be.. so if the od sends an 8 in pressure the most the last cable will send is a 4. If you put the buffer in front of the od so it now received and sent a 10, the cable could only send a 5 max (assuming double the diameter meant it needed double the pressure) - a small improvement but not the best

If you put the buffer at the end after the od, it would 'correct' the cable diameter and make it able to send a normal range again without needing more pressure. It could then send the 8 the od sees and give you the most treble bang for the buck you could get with that setup.

So yeah, good to mess around a bit sometimes to find what out you like

 

[Faded Abyss]

That means that the roll off from the pickups' mismatched load was greater than whatever came after the od, so you found the right spot!

Why do some people swear by putting it at the end then?
Imagine you had the worlds worst cable after the od, to the amp, and only 1 buffer to use. This could a good time to put the buffer last.

Lets say after the od, the 'straw' (crappy cable) it sees is double the diameter what it should be.. so if the od sends an 8 in pressure the most the last cable will send is a 4. If you put the buffer in front of the od so it now received and sent a 10, the cable could only send a 5 max (assuming double the diameter meant it needed double the pressure) - a small improvement but not the best

If you put the buffer at the end after the od, it would 'correct' the cable diameter and make it able to send a normal range again without needing more pressure. It could then send the 8 the od sees and give you the most treble bang for the buck you could get with that setup.

So yeah, good to mess around a bit sometimes to find what out you like

Remember, the OD itself is a buffer (when activated, if true bypassing), it’s just a different buffer that is coupled to the other circuitry of the OD.

Professional pedal boards will often have an input buffer at the very beginning that loads your pickups, and an output buffer at the very end of the pedal chain.

This way the guitarist will always have the same feel no matter what pedal is downstream of the input buffer. The output buffer is to send the signal to the amp no matter what. Not the best connection? 100 ft cable run? No problem. Look at the output impedance of the Mesa Send. 150 ohms. Look at the output impedance of a boss pedal: 10,000 ohms.

Having a separate output buffer or line driver is overkill for most circumstances. But most guitarist just don’t know why they like what they like which is fine. If it sounds good, it’s good. It’s just that there are simple technical explanations for a lot of these things that are objective. In my experience, I like the typical 10k ohm output to an amp more than a 150 ohm output but the difference is minimal.

 

[tjnx]

Remember, the OD itself is a buffer (when activated, if true bypassing), it’s just a different buffer that is coupled to the other circuitry of the OD.

Professional pedal boards will often have an input buffer at the very beginning that loads your pickups, and an output buffer at the very end of the pedal chain.

This way the guitarist will always have the same feel no matter what pedal is downstream of the input buffer. The output buffer is to send the signal to the amp no matter what. Not the best connection? 100 ft cable run? No problem. Look at the output impedance of the Mesa Send. 150 ohms. Look at the output impedance of a boss pedal: 10,000 ohms.

Having a separate output buffer or line driver is overkill for most circumstances. But most guitarist just don’t know why they like what they like which is fine. If it sounds good, it’s good. It’s just that there are simple technical explanations for a lot of these things that are objective. In my experience, I like the typical 10k ohm output to an amp more than a 150 ohm output but the difference is minimal.

In my case I was able to get more highs placing my last buffer after a mx carbon copy then about 10' of low-cap cable into the fx return. Is the difference due to the output impedance?

The output impedance on the cc is 1k Ohm vs < 300 (75?) Ohm on the cal redeemer buffer.

 

[Faded Abyss]

In my case I was able to get more highs placing my last buffer after a mx carbon copy then about 10' of low-cap cable into the fx return. Is the difference due to the output impedance?

The output impedance on the cc is 1k Ohm vs < 300 (75?) Ohm on the cal redeemer buffer.

you’re still going into the front of the amp and the FX loop is being used on a regular way, right?

The only reason I ask is usually people would put the delay in the fx loop so it makes me think you might be bypassing the preamp of the amp?

I’ve actually heard of carbon copy’s making the tone dark, so running a buffer after makes sense because it should keep your tone more consistent whether the carbon copy is activated or bypassed.

FX loops are a whole different can of worms. Impedance and level inconsistency to add to the equation because if an effects loop is buffered, a low cap cable should affect it? Hmm

 

[tjnx]

you’re still going into the front of the amp and the FX loop is being used on a regular way, right?

Yes for brevity I just listed the end but the signal chain (minus a few pedals in between) is basically:

gtr > buffer1 > pedal board > amp in > fx send > mxr cc > buffer 2 > fx return
6' cable up front then 3 10' cables for the board to amp and fx loop routing

Placing buffer 2 between my last pedal on the board (Boss sd1) and the amp input also adds some brightness but putting it at the end after the mxr cc gives the most effect. Looking at this there was a post on tgp where the cc does color tone even with its 'true bypass' so that could be part of it

It does improve the signal slightly though after the boss, despite its buffer.

 

[Greazygeo]

I always ran my buffer right after the guitar before all the pedals. That way the guitar volume knob works as it should straight into the amp.

 

[Faded Abyss]

Yes for brevity I just listed the end but the signal chain (minus a few pedals in between) is basically:

gtr > buffer1 > pedal board > amp in > fx send > mxr cc > buffer 2 > fx return
6' cable up front then 3 10' cables for the board to amp and fx loop routing

Placing buffer 2 between my last pedal on the board (Boss sd1) and the amp input also adds some brightness but putting it at the end after the mxr cc gives the most effect. Looking at this there was a post on tgp where the cc does color tone even with its 'true bypass' so that could be part of it

It does improve the signal slightly though after the boss, despite its buffer.

I just looked up the cal redeemer. I never heard of that, seems nice. You said you split off that? I’m sure you already found out if it can handle splitting the signal and driving 2 loads? In parallel, voltage will be the same but amps will split amongst the two loads which would require extra power so hopefully it has plenty of headroom there (but it doesn’t see like this has anything to do with the variables you are experiencing anyways)

A couple things regarding the FX loop: what amp is it? It’s so hard to keep up with all the different FX loops… some spit out a consumer leave which is a stronger signal than guitar pedals. Some spit out a line level but that’s more old school. In either case, the cable shouldn’t be a factor whether it’s low capacitance or not unless maybe your FX loop is un-buffered? I think some amps spit out buffered instrument level (similar to pedal outputs). I’m not saying your cable isn’t the culprit, just seems less likely.

It seems like leaving your second buffer right before the amps input (preamp in, NOT effects return), then finding a way to true bypass your carbon copy, or even better if your FX loop by-passable, and if you need yet another buffer there maybe get the same one that you know you like out in front?

I don’t think it would degrade the signal or then be too bright, because buffers are supposed to keep things consistent. Most modern amps have buffered send and return on FX loops I think. So it’s probably not overkill especially if your FX loop isn’t buffered.

 

[tjnx]

I just looked up the cal redeemer. I never heard of that, seems nice. You said you split off that? I’m sure you already found out if it can handle splitting the signal and driving 2 loads? In parallel, voltage will be the same but amps will split amongst the two loads which would require extra power so hopefully it has plenty of headroom there (but it doesn’t see like this has anything to do with the variables you are experiencing anyways)

A couple things regarding the FX loop: what amp is it? It’s so hard to keep up with all the different FX loops… some spit out a consumer leave which is a stronger signal than guitar pedals. Some spit out a line level but that’s more old school. In either case, the cable shouldn’t be a factor whether it’s low capacitance or not unless maybe your FX loop is un-buffered? I think some amps spit out buffered instrument level (similar to pedal outputs). I’m not saying your cable isn’t the culprit, just seems less likely.

It seems like leaving your second buffer right before the amps input (preamp in, NOT effects return), then finding a way to true bypass your carbon copy, or even better if your FX loop by-passable, and if you need yet another buffer there maybe get the same one that you know you like out in front?

I don’t think it would degrade the signal or then be too bright, because buffers are supposed to keep things consistent. Most modern amps have buffered send and return on FX loops I think. So it’s probably not overkill especially if your FX loop isn’t buffered.

No I don't split anything, I just have 2 buffers that I have tried in different positions. 1 after the guitar and 1 after the mxr in the loop gave the most improvement. I did get improvements keeping the first in place and trying the 2nd in front of the preamp but not as much.

Its a normal -10dbv fx loop but probably not worth getting into the minutiae over...all I know is that the cables are good and it works!

 

[Faded Abyss]

No I don't split anything, I just have 2 buffers that I have tried in different positions. 1 after the guitar and 1 after the mxr in the loop gave the most improvement. I did get improvements keeping the first in place and trying the 2nd in front of the preamp but not as much.

Its a normal -10dbv fx loop but probably not worth getting into the minutiae over...all I know is that the cables are good and it works!

Gotcha, yeah it’s usually not worth going down rabbit holes… unfortunately it’s my specialty. You know… know that we are on this subject… one of the options I always seem to forget about is all these load boxes that have fx loops of their own.

I’ve been fortunate with effects loops though… haven’t noticed any tone suckage. I am still plagued by tone suck from noise gates though. That another rabbit hole I need to revisit at some point

 

[matttornado]

Whatever sounds better, do it. other people's opinions mean nothing, your ears will decide.

 

[saxxamafone]

Whatever sounds better, do it. other people's opinions mean nothing, your ears will decide.

I did exactly this last night. Recorded various clips in different combinations.

Landed on whammy and overdrive before buffer, followed by everything else on my board

Last test is to try plugged straight to amp vs 1 buffer on my board (to determine if I need that 2nd buffer at the end of the board or not)

 

[Classic]

This is a very informative thread and plenty to agree with. The impact of a pedals output impedance can have an impact on the next based on the following pedals input impedance. I’m not taking mismatch of impedance specifically, just variances and the ability to tolerate slightly higher or lower values.

It’s also worth considering the tonal impact some buffers have on the signal. Ideologically a buffer shouldn’t have an impact however I’ve found some can create a spike in treble (primarily a reduction in bass) or a dip in the mids, appearing as too much bass and treble. Placing a different buffer/buffered pedal in the chain resolved it.

 

[The~Kid]

This is a very informative thread and plenty to agree with. The impact of a pedals output impedance can have an impact on the next based on the following pedals input impedance. I’m not taking mismatch of impedance specifically, just variances and the ability to tolerate slightly higher or lower values.

It’s also worth considering the tonal impact some buffers have on the signal. Ideologically a buffer shouldn’t have an impact however I’ve found some can create a spike in treble (primarily a reduction in bass) or a dip in the mids, appearing as too much bass and treble. Placing a different buffer/buffered pedal in the chain resolved it.

Yup this is why discretion is important.....


Not all bypass buffer or true are alike or the same quality sometimes and discretion is important. I also find an EQ pedal at the end of the chain helps bring back a lot of the life and tone suck that may occur in either case.

And also always use going straight into the amp as a baseline, then just your ODs, then everything else. This way you have a reference based on different baselines as to how much tone such there is and make a better choice in regards to placement and discretion.