Of I/O Impedance and Buffers

F

fretburner

Well-known member
Hi! I was wondering if the higher the input impedance for a pedal = the better it is as a buffer?

I have a few boss pedals and the I/O impedance for the AC-2, RV-3, GE-7, and LS-2 are 1M/1K ohms, while for my DS-1 it's 470/1k ohms. Does this mean that the DS-1 is a poor buffer while the rest are great?

I noticed the MI Audio Buff N Boost has a 5M ohm input impedance.
 
Re: Of I/O Impedance and Buffers

^ so below 1M are not good buffers, and therefore are better placed between good buffers in your effects chain?
 
Re: Of I/O Impedance and Buffers

^ Yeah. I'm really not a pedals type of guy. My signal is just Guitar --> OD -- > EQ --> Delay/Reverb (depending on the amp). Sometimes, it's just OD for greater saturation and EQ for boost during solos.

However, I'm doing a lot more variety songs - rock, pop-rock mostly - with this other band, and I need more modulation fx that I would really want to use in my regular band (which is "old school" heavy metal).

I also noticed the DS-1 (470k Ohm) doesn't like being with the other pedals I have. I always wondered if this buffer thingy has something to do with it. Same with the other mod fx.
 
Re: Of I/O Impedance and Buffers

fretburner said:
^ so below 1M are not good buffers, and therefore are better placed between good buffers in your effects chain?
Click to expand...

The DS-1 is a distortion pedal, not a buffer!

All you need for a buffer is for the input impedance to be significantly higher than the output impedance of the previous stage. Guitar pickups typically have resistances of what, 5-10k? So a 470k input impedance is 50-100 times that, which is enough for it not to cause significant problems. A 1M input impedance is better. A 2M one probably isn't significantly better than 1M.

It's all about the interaction; having a high input impedance means that most of the signal is dropped across that input rather than in the connecting cables or (worst of all) across the output of the previous stage.

The DS-1 may not play nicely with your other pedals for all sorts of reasons, but I'd not think the 470k input impedance the most likely suspect.
 
Re: Of I/O Impedance and Buffers

I just "bumped" into a DOD YJM and noticed it's got a 4M Ohm buffer: DOD YJM

DOD YJM308 Yngwie Malmsteen Overdrive Pedal Specifications

* Input Impedance: 4 M ohms
* Output Impedance: 100 k ohms
* Maximum Input Level: 6 V
* Power Supply: 9 VDC

Does this mean I can use it as a buffer? I have one but don't really use it - too bright for my taste. But I wonder if I can just leave it in my chain to act as a buffer?
 
Re: Of I/O Impedance and Buffers

If the YJM OD is not true bypass, then it will buffer your signal when the effect is switched off.

As for the DS-1 not playing well with other pedals, is that when other pedals are before it in the signal chain, after it, or both? I find to my ears, that I do not like any buffer before my OD boxes. So, I tend to use true bypass OD boxes, I usually have at least 2. My wah is true bypass as well, before my OD boxes. After the OD boxes, it's usually a matter of taste. To me, too many buffers doesn't sound right, I like one ore two at the most. All true bypass doesn't work so well either.

The DS-1 indeed has a buffer in it, as all Boss pedals do.
 
Re: Of I/O Impedance and Buffers

^ The manual doesn't say anything, but found this at analogman.com

"These pedals are not true bypass, but due to the simple design they really don't suck tone when OFF. There is no resistance on the input when OFF, and just a tiny bit of capacitance. The capacitance is about .001uF on the stock one and about less than .01uF after the mod. That is similar to the capacitance in a quality 15 foot guitar cable- you probably can't hear it. But if you want, we can do a true bypass mod along with the Grey DOD250 mods by installing a 3PDT True bypass switch ($15) and LED ($10, red, yellow, or Green). We can also change the 1/8" MXR style power jack to a Boss style, for $10 (an option on the mod form) and you can order our Generic adaptor ($15) on the mod form too. In order to install an LED, we need to change the switch to a 3PDT True Bypass switch."

Not sure about the "no resistance when off" thing though?

As for the DS1, I can't remember exactly what my set up was the last time I tested it. I do remember using it as an OD/Boost for 1 distortion pedal, with great results. I'm going to have to try it again.
 
Re: Of I/O Impedance and Buffers

It sounds like the YJM is not buffered then. It most likely uses a bypass sometimes called hardwire bypass. This similar to a true bypass, but the signal still passes through a small circuit. it gets confusing, some companies call it a true hardwire bypass. Some companies call their true bypass designs true hardwire bypass, so you will defiantly have to do some research occasionally.
 
Re: Of I/O Impedance and Buffers

^ I guess I can use it as a buffer then, by just putting it in my chain and not every stomping on it right?
 
Re: Of I/O Impedance and Buffers

fretburner said:
^ I guess I can use it as a buffer then, by just putting it in my chain and not every stomping on it right?
Click to expand...

Not exactly sure to tell you the truth! It seems like no to me, but I could be wrong. But your DS-1 will buffer your signal for sure.
 
Last edited:
Re: Of I/O Impedance and Buffers

The DS-1 may not play nicely with your other pedals for all sorts of reasons, but I'd not think the 470k input impedance the most likely suspect.
Click to expand...
Yeh it does the buffer when the pedal is off effects other pedals more then other BOSS pedals do. I notice this with my early version Pinnacle II which most have a fairly high output impedance but through the ds-1 off it sounds a fair bit different to straight and even through other BOSS pedals. Don't forget the DS-1 is quite an early design and I don't think they've changed it much at all and alot of well buffered pedals sound alot better bypassed. The YJM is classic DOD and MXR dpdt (when using an led) switching where it doesn't go completely out of the circuit and this tends to sound kinda bad (like most non TB wahs are) it is the worst kind of bypass but a buffer infront can help. Good buffers are the MI Audio Boost and Buff. The Wampler Pedals Buffer, Roger Mayer stuff along with alot of others.
 
Re: Of I/O Impedance and Buffers

^ The Boost n Buff had a 5M Ohm input impedance, while the DOD YJM has 4M Ohm input impedance. I'm sure the input impedance is not the sole factor, but I'm guessing having a DOD YJM will help?

I use 20-foot cables and use the FX loop on my gigging amp. That's 80ft ++ of cables. I like the sounds I'm getting as it is right now, and I'm not worried about loosing highs since the JCM900 is already bright for my taste.
 
Re: Of I/O Impedance and Buffers

^ The Boost n Buff had a 5M Ohm input impedance, while the DOD YJM has 4M Ohm input impedance. I'm sure the input impedance is not the sole factor, but I'm guessing having a DOD YJM will help?
Click to expand...
As the YJM doesn't have a buffer this can only really apply when the DOD is on as its passive when off and will only degrade the signal.
 
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