Guild Dimensional Reverberation System

I bought this Guild Dimensional Reverberation System when it popped up for sale a couple of years ago figuring that I’d never seen one before so it might be fun to research and write about. I’m not sure “fun” was the right expectation because after moving it around on my desk for over a year, well, read on and see for yourself.

Introduction

I have a pretty significant collection of Guild catalogs that I use for research, and I couldn’t find this item in any of them. Without a clue as to when it was even made, I had to resort to opening it up to try and get date codes off of the internal components where I was flummoxed once again.

After taking the unit apart (four screws on each corner of the metal cover) and flipping the metal cover over I was greeted by two ridiculously corroded potentiometers. Since no other components had any date codes that I could discern, I was stymied once more. What to do? Hmm… How about Gorgomyte!

One of my favorite guitar-based products is Gorgomyte which helps to clean frets and fretboards without harsh chemicals and without resorting to 0000-guage steel wool which works great, but is a pain in the butt to deal with. Taking a small strip of Gorgomyte, I rubbed on the back of both pots and was delighted to see that my idea was sound because the pots shined almost like new, revealing very easy to read date codes. The date codes on the pots indicate that they were manufactured in the first week of 1967, so I presumed this reverb unit to be from the same year, or at least within a year or so after that date.

After spending far too many hours trying to find an ad or a catalog or anything containing the Guild Dimensional Reverberation System, I came up with precisely nothing. Zip. Nada. Bubkis. So I emailed Hans Moust, writer of the Guild Guitar Book, with whom I have an amiable relationship wherein I badger him with weird questions and he politely answers, no doubt too polite to ask me to stop asking him such weird questions.  Sadly, even Hans had no information for me, and you know you’re in deep when Hans can’t help you with a Guild question.

In my quest to see who actually made this unit, I did find many similar units like the Fender FR1000, the Lafayette Echo VerbLafayette Echo Verb II, and even the Unicord Univerb, all of which seem to share the same basic principle of a reverb tank driven by a transistor-based circuit, but none that matched the Guild precisely.

Many searches pertaining to Guild Reverb, when not matching amplfiers with reverb in the name, seemed to hit on the old Binson Echorec and Watkins/WEM Copicat tape echo machines, probably because those were actually popular and well-regarded units wheras the Guild Dimensional Reverberation System seems to have been lost to obscurity.

Based on the fact that many of the internal components seemed to have been made in Japan, I started widening my search a bit and stumbled on this Japanese reverb tank called the Reverb Master which struck me as being very similar to the Guild Dimensional Reverberation System due to it having the exact same controls and input/output jack, though they were arranged differently. Naturally, I did what any other frustrated guitar archeologist would do: I found one and bought it in order to disect it. You know… for science.

Sadly, they are completely different beasts. As we’ll see when I examine the electronics below, the Guild has a full-sized 2-spring reverb tank while the Japanese unit has a single-spring tank and contains less robust components. I should also point out that it wasn’t until I got the Japanese unit in my hands that I noticed that the controls are not the same as I had assumed. On the Guild the two knobs are Volume and Intensity, while on the Japanese reverb the two knobs are Depth and Tone. Also the Guild unit says Made in the USA right on the top. I think I may need a vacation. Or new glasses.

For now, the source of the Guild Dimensional Reverberation System remains a mystery. If you have one or know anything about the story behind this rare piece of Guild hardware, please contact me or leave a comment.

Controls

There are only three controls evident on the Guild Dimensional Reverberation System: Volume, Intensity, and the on/off switch. There is a fourth control available when a foot switch is added, and the foot switch is simply a means whereby the reverb signal is shunted to ground. The on/off switch has its tab broken off on my example, but it still functions, so that leaves the two big knobs on the front.

The first knob is volume which is a bit odd because it appears to be capable of muting the signal entirely. That’s not something I’d consider a value-add in a tool like this, but it may also be able to provide a bit of drive which is interesting, though sadly I could not prove this since my unit is essentially non-functional.

The Intensity knob is what controls how much reverb you get in the signal which, given my experience with other Guild electronics,  is likely adjustable from none to please make it stop, but as I already mentioned I was unable to prove any of this.

Electronics

The Dimensional Reverberation System is basically a spring reverb tank with a small driver circuit and power supply packed into a nice metal and wood case. The two inputs in parallel and the gain is provided by an old transister making this a solid state unit as advertised on the top.

This is a metal-cased electrical device that has no ground lug on the plug. Is that bad? Yes. The end.

OK, not the end. Why is it a problem? Because the case is metal and there is no grounding through that missing third lug, so any time you touch the chassis you risk becoming the ground path, and as anyone who was around when guitar amps had only two lug power cords and a ground-lift switch will tell you, getting shocked it not fun and can even be lethal.

The tank is 9.25 inches long from flang tip to tip with two springs. I could not find any markings at all on the tank though it is possible there are markings under the circuit board since I did not remove that. This device was made back in the days when point-to-point wiring was still a common assembly technique, even when combined with turrets and circuit boards as seen here, so moving components without unsoldering the entire affair is not a simple process.

The two input jacks are wiring in parallel which means plugging in two instruments can change the impedance of the input and cause some nice tone-suck. Since the inside of the unit is wired with a combination of wiring and since there are directly soldered components along with big capacitors crammed in where they found room for them, getting more detail than what you see in the pictures was not possible unless I wanted to pull it all apart.

I was not willing to pull it all apart. Unfortunately, the Guild Reveb… you know what, I’m not typing that all out anymore. This Guild thing doesn’t work. see? Much simpler.

The solid-state nature of the Guild Dimensional Reverberation System (is that name ridiculous or what?) means that it’s driven by transistors instead of tubes. There appears to be three in the circuit, and they all appear to be completely lacking labeling of any kind. That, coupled with the fact that pulling the circuit board off of the reverb tank seemed like a bad idea means that a) I can’t really tell you what’s going on electrically and b) I couldn’t fix it because I don’t have a schematic. Remember, my attempts at finding any useful information about this thing came up empty, so short of completely dismantling it and testing each component or tracing it all out and making my own schematic, it will sadly stay broken.

Meet Mr. FET ... the Transistor That Thinks It's a Tube, February 1967 Popular Electronics - RF Cafe
As a fun aside, while searching for vintage transistor information (specifically vintage transistors in unmarked little cans like the one in this unit’s circuit) I stumbled across this delightful picture from this website that describes what a FET (Field Effect Transistor) is and what it does from the February 1967 edition of Popular Electronics. I think the black transistors already look like the Tripod Fighting Machines from the original War of the Worlds. If the little FET cans can have an identity crisis and talk about it, well then it may be time for me to up my meds.

Sound

So far as I can tell this unit was designed to be a state of the art tone-suck machine, but there’s something wrong with it so that’s probably not a fair assessment of its capabilities.

It powers up fine, and a degraded signal flows through it, and it even makes the proper thunderous noise when I rap on it with my knuckles, but unless I can prove that the drive circuit will make me sound like Brian Setzer or that the reverb will make me sound like The Ventures, restoring this rare Guild Dimensional Reverberation System (seriously, it’s not a system. It’s barely a unit!) will be relegated to the back burner behind the other 419 projects in the pile.

Conclusion

This is an interesting piece of Guild guitar history, but I’m not sure I would seek one out to be the secret of my tone, and even if I were to recommend such a thing, the chance of finding one of these Dimensional Reverberation Systems (man, am I tired of typing that) seems to be extraordinarily small.

Oh, and how many times did you look at the pictures and not realize that the printing on the top says Dimensionl Reverbration System? I can tell you that I had mine for a year and wrote this entire article before noticing that during a final edit, and I only noticed because I was going to comment on how the name is oddly left justified on the cover. Maybe they never made it big because the copy editor was drunk or stoned that day. It was the ’60s after all.

If you’ve got one that works or even looks to be in better condition than mine, please leave a comment. I’d love to see and hear it!

 

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