questions about buffers.

[9Lives]

I'm really curious as to how these work. I can't seem to find any real good info other that (beavis audio). I really want to build somthing with a buffer in it but I'm just not really sure what I'm talking about lol. I don't want to build just a buffer, I would like to use it as a bypass and I just can't figure out how to do it once I build it. (the TL071 buffer) is there a way to wire it to the switch? Would it toggle between the effect and the buffer? Any kind of info would be appreciated. Thanks!

[jkokura]

What do you mean by bypass? Do you mean a master bypass? Or do you mean you want to bypass the buffer?

Jacob

[JakeFuzz]

A buffer is an impedance transformer. On one side you have very high input impedance and the other you have very low output impedance. This is used to match the impedance of the circuits on either side of the buffer to prevent very high impedance differentials called loading, which can cause the circuit to not operate optimally. The best example is the opamp, by definition the opamp has theortically infinite input impedance and very low output impedance. That is why many of the buffers you see in circuits are just a positive unity gain amplifier using an opamp.  

Yes you can switch it in and out of the circuit as you like. Jacob is right though you can have total master bypass or buffered bypass, it all depends on what you want to do with it.

[9Lives]

ok, that made some since to me. Jacob, I think I saw a pedal on your page that had a switch that switched from true bypass to buffer.. I might  be wrong. But lets say and mxr pedal is a true bypass, a boss is a buffer. What is the difference between the two. When bypassed does the signal actually go through a different sort of circuit where as the true bypass goes directly from input ot output? Bear w me guys I'm  still learning. I looked on the beavis audio sight and  there was a schem for a buffer using the tl071. Would you use that as the bypass rather than the true bypass? If not how would I do this?

[crash]

9 lives, In a true bypass pedal, when bypassed, the signal goes directly from the input to the output.  It does not go through any other part of the pedal.  In a buffered pedal, the signal will always go through the buffer, whether the pedal is "on" or bypassed. 

Here is my analogy to buffers, please correct me if I am wrong.  Think of the cord from the guitar to the amp as a pipe flowing water.  The buffer acts like a "pump" helping push the water along.  Without any buffers, and driving a long cord, you can lose some signal, mostly the highs.  If you have a buffer in there, it helps the signal along so it can get to the amp.  The reason why some people don't like buffers is that they can sometimes "color" the signal.  Although some people like this coloring that a buffer can add.  It's all just a matter of taste.

[9Lives]

nice, that made some since to me so if I wanted to build a pedal with a buffer would you wire the switch the same way? Or is it different. How would I add this to a build or do you have to redo the whole circuit. I guess it couldn't be the same wiring if the signal still goes through the circuit. Ok yall are great. I'm learning.

[jkokura]

nice, that made some since to me so if I wanted to build a pedal with a buffer would you wire the switch the same way? Or is it different. How would I add this to a build or do you have to redo the whole circuit. I guess it couldn't be the same wiring if the signal still goes through the circuit. Ok yall are great. I'm learning.

Buffered versus True Bypass is a big arguement, and you won't get consensus in the DIY world. You're asking a question that really can't be answered easily. Most of us, myself included, always build our effects with true bypass, and the reason is that it's easier, and it's very popular right now. Recent developments in the DIY world have made 3PDT switches very, very economical. In fact, they're more economical than buffered bypass is by far. That wasn't the case 10, or even 5 or 6 years ago, when these 3PDT switches were less common and more expensive. My last batch of 3PDT switches cost me 2.50 each including shipping to Canada!

Buffered bypass is more complicated, and needs some depth of knowledge about how effects work that most DIYers don't have access to. Some effects that use Buffered bypass from back in the day have given buffered bypass a bad name, and you shouldn't put much stock in that. Most of the time, buffers are good, and one of the major reasons they are helpful in large quantity builds is that they allow you to use silent or 'clickless' switching, and allow for easy to access and cheap single pole switches for bypass instead of cumbersome and labour intensive 3PDT switches.

If I were to build an effect that needed to have a buffered bypass, there are two ways to do it. You can either include a buffered bypass into the design of the circuit so that it would be built right into the circuit board which is how Boss, Ibanez, and pretty much all the big companies do it. Some the effects you can build from Madbean are the same, like the Sunking and Darkside projects. The other way to do it is to build a separate buffer and then put it inline with your input jack and switch. The buffer is then ALWAYS in the circuit, whether the effect is bypassed or not. I would do this if you're not up to designing your own layouts or understand how buffered bypass works really.

I wish I were able to give you the full answer on this one, and I think R.G. would be a better person than myself for explaining it. Here's a link to a GEOfex article written by R.G. Keen:

http://www.geofex.com/article_folders/bypass/bypass.htm

Jacob

[9Lives]

Jacob, perfect. That's actually exactly the answer I was looking for with in your explanation of how you couldn't answer my question LOL. Your solution with connecting the buffer to the input is what I was looking for and kept over looking. I guess if you did that you would go (input tip)-->buffer-->in to the 3pdt? (i use the 3pdt pcbs) that would be an extremely overkill way of doing this but away to experiment with buffers. Couldn't you put the buffer on it's own spst toggling between buffer and true bypass?

[TNblueshawk]

Many folks build a little mini buffer in a tiny enclosure and have one in the beginning of the chain and maybe at the end too at times and have all bypass pedals in the middle between them.

Pete Cornish has a ton to say about buffers.