Grateful Dead Music Forum

Thinking about a xmas present for myself. I have done quite a few searches and can't seem to find a simple answer/comparison on the difference between Unity Gain & Non-Unity Gain. It would seem UG would be more desirable (both objectively, practically and from what I can tell in getting certain tone characteristics) but Waldo's preamps are stock Non-Unity. Why? Is it merely nostalgic to be more Garcia-like or is there a qualitative reason?

Thanks in advance.

It's pretty simple. Jerry didn't need/want a lot of added gain because his rig was so loud that he had enormous volume available with just the volume control on the guitar. The purpose of the pre/buffer was to maintain the highs and to not lose tone when using long cable runs. It was not meant for a lot of extra gain. Just a little.
If you watch Jerry, he works the volume control A LOT and you can hear when he turns it up for certain solos how loud it can be. That is the best gain.

Edited to remove incorrect information.

So unity adds some gain that isn't present in a non-unity gain?

Unity is unity, gain is gain

Why not have the choice? As in a blaster with adjustable gain? Then you can choose... I'm sure you could modify the Wald design to have adjustable gain too. He offers an actual Unity model also.

My head is spinning...

Unity is unity, gain is gain

I'm just trying to understand the difference between the two Waldo options - one with and one without unity gain. Is one better or is there a perceived qualitative difference?

As in a blaster with adjustable gain?

The only con I can think of is having to drill to add the extra pot? Else I might go that option. Also it seems options with adjustable gain such as the Jangletone II eat batteries faster, not that it is a huge deal.

The way Waldo explained it to me when I got my TPC1 a few years ago was that the non unity gain buffer allowed Jerry to turn up his Fender pre-amp vol a bit further to compensate. This resulted in more voltage going through the pre-amp tubes, which can be tonally desirable.
Hope I remembered that correctly!

The only con I can think of is having to drill to add the extra pot? Else I might go that option. Also it seems options with adjustable gain such as the Jangletone II eat batteries faster, not that it is a huge deal.

Yeah, I don't mind the extra hole... I like the control. I'm sure that the more gain you use, the faster the battery goes; but with the adjustable Blaster I use, I don't notice it going away quickly, it seems to last a long time. Then, I don''t use a really high gain setting most of the time... I generally switch between 'close to unity' bypassing the pot all together, and about 3 on the dial... although I noticed lately that turning the gain up to 8 or 9 and turning the guitar volume down yields some nice sounds.

I own and have used both the CAE and Wald buffers. I ordered both unity gain. Some effects seem to me to function at their best when hit with a normal, i.e., unity gain signal. You can always turn your overall volume down afterwards with your volume control (and even put effects you want to vary the volume to between your post-OBEL guitar out and the amp). Note, though, that I'm not and have never been in the "have to do everything just like Jerry did" camp - if that's your goal, you already have your answer!

flyingheelhook wrote:So unity adds some gain that isn't present in a non-unity gain?

Not quite.
Unity gain is the pickup's original output.

The Wald TPC-1 is not unity gain. It has a small amount of gain.
The "unity gain" version has no gain.

Edited to remove incorrect info.

In the idea of unity gain, the input and the output between two devices are the same level. That's to say, when a microphone is outputting 0db, a mixer will also be outputting 0db worth of signal. Unity gain is established by calibrating two pieces of equipment to talk at the same level.

http://homerecording.about.com/od/homes ... y_gain.htm

A gain of factor 1 (equivalent to 0 dB) where both input and output are at the same voltage level and impedance is also known as unity gain.

http://en.wikipedia.org/wiki/Gain

Unity means signal in = signal out
Gain means signal in < signal out
According to Mike W. Jerry did not use a Unity buffer, his actually had some slight gain, which is what the TPC-1 is modeled after. Mike developed the unity buffer in response to requests for actual unity, not what Jerry used.

From Waldos site:
"Unity Gain simply means the Gain that goes into the preamp is equal to the Gain sent back out of the preamp. The Stock TPC1 is NOT Unity Gain, but for those that need or want the Unity Gain version it can be selected as an option."

I want to thank Jon S for the links he provided. Thanks, Jon S!

Ok, so after thinking this over again and again and reading the info provided by Jon S and Waldos site as quoted above, I was mistaken in my last post and I have deleted it for that reason.

So, "unity gain" IS equal to the original signal (no gain added). Therefor, the stock Waldo pre/buffer TCP-1 that Jerry used IS adding a little gain.

Sorry for the confusion. The terminology is somewhat confusing. That is the problem, but we got it right now.

milobender wrote:Unity means signal in = signal out
Gain means signal in < signal out
According to Mike W. Jerry did not use a Unity buffer, his actually had some slight gain, which is what the TPC-1 is modeled after. Mike developed the unity buffer in response to requests for actual unity, not what Jerry used.

This is an excellent explanation and correct as well.

I found the email exchange I had with Waldo from 2010:

You state that "The TPC1 is not a Unity Gain Preamp. A Unity Gain version is optional at time of purchase". Could you explain the difference further please.

Unity gain is essentially the same output level as the pickups with no buffer. what goes in level wise is what comes out. with the stock TPC1 it is slightly less then unity or slightly less output level. what this accomplishes is that you can run your preamp a notch higher in level vs. unity output. in tube preamps this gives a slight increase in voltage to the preamp tubes and for some, and jerry, this was a desired effect. tone wise from the guitar standpoint there is no tone difference unity or slightly less. as i stated, it is just an output level.

You guys rock!

I'm definitely not chasing a Garcia tone - in the bands I play in I'm the Bobby guy!

I'm just looking for the benefits an onboard preamp offer and making sure I understand the options available before I take the plunge.

Thanks to you all!!!