I built myself a 14" x 32" pedal board earlier today. I've still got some work to do on it, but it's almost finished. I'm going to add jacks into the sides (guitar/amp) to minimize wear on the pedals' jacks, and I'm going to make some holes to pass the power cables from underneath.

Here's what it looks like so far, with a couple pedals on it:





The slot in the middle of the back there not only lets the power cable through but allows one of the feet of a mic stand to slip under, bringing the pedal board nice and close to the mic stand.

I've been hearing a lot about how unity gain buffers such as the VHT Valvulator and the CAE CB-1 are supposed to convert the guitar's high-impedance to lo-impedance, to prevent signal loss from a long effects chain (or simply a long guitar cable). Aren't these just glorified DI's?

Here's my question: What's the difference between these devices and DI box? Or am I misunderstanding the function of a DI box?

Why are you asking me? I have no idea.

A DI box electrically isolates your equipment's potential from the electrical potential of the sound system, in addition to converting from unbalanced hi-Z (1/4 inch) to balanced low-Z (XLR cable). This happens after your effects are processed.

Unity gain buffers convert the impedance on your guitar's output to lo-Z before your effects chain (It is a pre-amp after all. ) without changing the connector type.

Without diving too much into electronics, impedance (abbreviated with a Z) is the sum of resistance in a circuit containing inductors (in this case, the guitar's pickups) and resistors in (I think) a series layout. Less impedance would make your output higher to compensate for signal loss through your effects chain, but if it's something you don't need, you might end up with unwanted distortion.

Thanks Brandon. I know what impedance is though. I was just wondering, if there's a difference between a DI and unity gain buffer, and from what you tell me, the only diffence is the place in the chain.

Basically you could do the same thing as the buffer by going

Guitar -> DI -- XLR-to-1/4" cable --> effects -> amp

if I understand correctly?

Oh, and something not so funny - I tried to take my Wylde OD pedal off the board. The velcro held on to the carpet so tightly, that the PAINT separated from the pedal.

That wouldn't work because you wouldn't have the gain part in effect before your effects.

Personally, I don't know anyone who uses a unity gain buffer, and they use tons of effects and still have a bright sound to their guitars. I've used cables as long as 25 feet and never lost any noticeable signal amount. So I don't really see a point. If you don't notice a difference either, I wouldn't worry about it. Each stomp box amplifies the signal anyway. I have one cable in particular that (just because it's older than I am) kills my high end for some reason. But that's the only example I can think of.

If you have at leasta fairly good understanding of amplifier circuits, this explains a bit about unity gain buffer circuits. Rather than a glorified DI box, they're glorified OpAmps.

Now if these particular UGB preamps alter the signal in other ways, that might be a different situation.

you don't really need one with such a small effects chain

if you add more pedals (especially if they have true bypass switching) it might be a good idea

Thanks again, Brandon. From your link, I see what you mean by a glorified OpAmp. :p

I was looking into this because I am looking at expanding my effects chain (I've got a Sansamp TRI-AC on its way in the mail). I know the BOSS is true-bypass, and the SD wah is a hard-wired true bypass, I'm not sure about the Wylde OD though.

I asked the question on the Cakewalk forums, here's a couple replies that I got: