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tone and volume on top plate actual effect?

Posted: Wed Sep 12, 2018 8:50 am
by Brian Evans
To me it's almost an insult to put the tone and volume pot's on the top of a truly acoustic archtop - but is it really? Has anyone ever done a proper A-B comparison of the same top before and after controls have been fitted? Is the impact negligible, dramatic, you could kind of tell in an A-B test but not after a few days to forget the exact tone quality?

One reason I ask is that there seems to be about zero market for true acoustic archtops, even Benedetto rarely gets a commission for one. The reason, of course, is that mostly pro players buy them and mostly pro players need a pickup and a guitar biased to perform on stage at a certain volume. I am thinking of adding a neck mounted floating pickup to my latest build, and since I don't use a finger rest was leaning towards the top mounted controls, which I actually quite like as a period visual statement. But I cringe when I think of drilling the top and adding the mass of the potentiometers and other wiring inside the box.


Re: tone and volume on top plate actual effect?

Posted: Wed Sep 12, 2018 12:19 pm
by Alan Carruth
Pots don't add the mass that a P/U does, but I know how you feel.

Added mass on the top does help to reduce feedback. That's a problem when you have to compete with a sax or trumpet. It may be why the players like to ones with top-mount pickups, even though they don't have the acoustic sound.

IMO the rule is: "if the room can hear the guitar, the guitar can hear the room". With enough gain in the loop anything will feed back. There are ways to deal with it, up to a point, but there are limits.

I guess the next question is, what do you have against finger rests? I've used them to mount the controls for a pickup that either mounts to the neck or floats off the finger rest, and sometimes both, and they do make a handy place for controls.

Re: tone and volume on top plate actual effect?

Posted: Wed Sep 12, 2018 12:41 pm
by Barry Daniels
Slide pots under the edge of a pickguard are a very slick solution.

Re: tone and volume on top plate actual effect?

Posted: Wed Sep 12, 2018 1:12 pm
by Brian Evans
My playing style suffers if I have a finger rest, I anchor there and it screws me up. I could probably get used to it, but my thought process kind of said "wait, maybe the other isn't so bad after all. You don't actually know, you just assume - and you know what that means..."

Allan, when I toured Benedetto in the spring they had exactly one acoustic guitar in the house - the 50th anniversary model they just finished making. Every other guitar had a set-in pickup. They do the bracing completely differently - they use heavier "parallel" bracing, with cross-braces where the pickups go, and rout the pickup hole to just go into the braces, so the pickup is surrounded by brace on all sides. I'm going to guess and say that over half their production (around 10 guitars a month) are laminated top and back plates. They do their own laminating with three layers of 1/16" thick veneer.

Re: tone and volume on top plate actual effect?

Posted: Thu Sep 13, 2018 12:21 pm
by Barry Daniels
Brian, this is very interesting and confirms what I have seen with a couple of other acoustic archtop builders that I know well.

So, in that vein, you may want to make your own version of a more electric, stiffer archtop and install the electronics in the top and not worry about acoustic effects.

A couple of questions, did the Benedetto factory also put potentiometers in the top and are these electric archtops thinner than a full-on acoustic?

Re: tone and volume on top plate actual effect?

Posted: Thu Sep 13, 2018 1:49 pm
by Alan Carruth
It's a continuum from the full acoustic all the way to solid body, and you can work anywhere you want along the line.

I made a couple of acoustic electric archtops some years ago. Those both had finger rests where I mounted the controls.I had a heavy wood beam that ran from the neck block to the tail block, and mounted the pickups on that. The top was more less 'normal' with holes cut in it for the pickups to poke through. On the first one I used a spruce top, but it was too active, so I made another with a maple top and only on F-hole. It worked pretty well, but UPS destroyed it. The small hole and heavy top kept feedback down, but the top was still 'tuned' and active enough to contribute some color to the tone. I found it helped to keep the sound output low in the low range; it seems to keep more sound in the strings for the pickup to pick up.

The upper bout part of the top doesn't move as much as the rest, and might make a good place to mount controls. I've done that on flat tops.

Re: tone and volume on top plate actual effect?

Posted: Thu Sep 13, 2018 7:21 pm
by Jim Hepler
Brian, I know this doesn't answer your question, but you could just wire a floating pickup directly to the output. Set the volume and tone on the amp where you want it. If you need to make adjustments on the fly, I actually prefer a volume pedal since my hands are busy when I'm playing. I'm more likely to want to adjust volume than tone when I play, but there are also various switchable eq pedals that could work for tone adjustments. It's true this might be a hard sell for generic customers, but it's very workable if it's for you. I suppose another option would be to put the controls on the side like you see on acoustic guitars with pickups. Taylor and others use low profile knobs and no visible plastic box, and the look is pretty unobtrusive. Don't know where you find those parts, but it's another thought.

As to your original question about the effect of putting pots on the top, I don't really know. My prejudice is against it, but I have no actual evidence to support that. I don't mind a pick guard so I'm inclined to favour putting those thumbwheels (schatten?) under the pick guard if I want on-guitar controls. My 2 cents.

Re: tone and volume on top plate actual effect?

Posted: Fri Sep 14, 2018 9:05 am
by Mike Conner
I also dislike finger rests or floating pickguards on archtops. For me they are in the way and a source for rattles or buzzes.

I have been using Schatten thumbwheel pots purchased through StewMac and installing them on the inside lip of the bass side F-hole. They sell a kit that includes the capacitor (of course you could swap cap out for another preference). ... trols.html

For my most recent installation I installed the pots in a modified plastic box, shielded with copper tape:
N7-301 Thumbwheels on box lid.JPG
With the guitar completed, they look like this:
N7-132 Pots in f hole.JPG
This guitar is actually a stereo output. A surface mounted StewMac Golden Age humbucker is wired to the tip and using the thumbwheel pots. The ring connection goes to JJB piezo transducers. I removed the HB pickup legs and mounted to the front plate using heavy duty exterior grade mounting tape with no window cut in the plate for the pickup:
N7-131 Side view HB and neck extension.JPG
I setup and play my builds in the white, make adjustments, then disassemble for finishing. I did not notice a big difference in acoustic tone with the humbucker surface mounted. I assume it is because the humbucker is basically right above the upper arms of the X brace and this area of the front plate is not a big contributor to volume or acoustic tone.

Hope this helps!

Re: tone and volume on top plate actual effect?

Posted: Fri Sep 14, 2018 10:55 am
by Chuck Morrison
I also share an aversion to cutting holes and mounting pickups onto a carved arch top. It just seems wrong to put so much work into it and then defile it with electronics. I do realize the economic necessity, but I've always felt that an acoustic guitar was a different beast from an electric guitar and by necessity needs to be built differently. Feedback issues if nothing else seem to demand it. Even my old Guild CE-100D plywood archtop would feedback horribly. Still, I prefer a neck mounted pickup for arch tops on general principles with pickguard mounted pots. However I don't like having a pickguard in the way when finger picking.

As far as sound goes, I wouldn't expect much difference in the acoustic sound from a pickup near the neck block, but I would be wary of anything near the bridge. The other question though is what mounting a pickup on a mobile part of the top do to the sound from the pickup? I think most would agree that the ideal is a very stable pickup location and let the string do the moving. Moving the pickup around at the same time could have interesting and undesired effects. Maybe that's why my old Guild fed back so badly.

I always liked the Guild George Barnes acousti-lectric concept, which had the pickups mounted on supports under the soundboard, poking up through (sound) holes in the top, so the pickups never touched the top. They looked a bit odd at the time with no F holes, but maybe not so odd 50 years later. It might be time to revisit that concept.

Re: tone and volume on top plate actual effect?

Posted: Fri Sep 14, 2018 11:42 am
by Randolph Rhett
My arch top builds are all “acoustic”, even some nylon string. But you are right, there is precious little market for that. For 95% of all arch top buyers (which is already a tiny number) the arch top guitar is a Cadillac of bling ELECTRIC guitar.

There is good reason for that. Most acoustic guitar players want a guitar to accompany vocalists. It’s hard to do better than a dreadnought with its boomy lows and shimmering highs. Acoustic arch tops lend themselves to the far more difficult task of solo guitar playing. More like a classical guitar, but without the heritage, history, or body of work.

As an electric guitar players have many examples of talented players. From Charlie Christian to Pat Methaney you have a wide variety of guitar heroes on electric arch tops.

My personal philosophy was to choose: do I build acoustic guitars for me and three or four other people a year, or somehow try to capture a slice of the electric guitar market? I’m not sure how anyone can make a living as a luthier today, but I’m grateful I don’t have to. That means I build the guitars I want to play, and consider myself blessed to sell a few here and there. Two pickups and four controls are NEVER going to live on the top of one of my guitars*

*of course, I was persuaded to make one just like that a few years ago for a charity auction, so I guess “never” is too strong a word ;-)

Re: tone and volume on top plate actual effect?

Posted: Fri Sep 14, 2018 12:48 pm
by Chuck Morrison
My choice as well, and yes there are not nearly enough Maybelle Carters around these days.

Re: tone and volume on top plate actual effect?

Posted: Fri Sep 14, 2018 10:09 pm
by Rick Milliken
Brian, thanks for asking the question! The responses have been very informative. But, mostly I'm glad to know I'm not the only one that struggles with the notion of drilling holes and adding buttons, switches and wiring to my "pride and joy"!

Re: tone and volume on top plate actual effect?

Posted: Sat Sep 15, 2018 8:27 am
by Brian Evans
I think I will get some modeling clay or double sided tape and stick a mass equivalent to the pots, knobs and wiring to the location I have in mind. I guess the thing is I know lots of ways to get the job done without the holes, but if you are recreating a period of history the thing should look the part, so it's a visual element that I am curious about as well as all the rest. I probably won't do it, at the end of the day I never play any of my electric guitars anymore.

Re: tone and volume on top plate actual effect?

Posted: Wed Sep 19, 2018 12:15 pm
by Alan Carruth
I'm on the road, and somewhat preoccupied, or I would have thought of it sooner: poster adhesive is far better than modeling clay when you want to try the effect of added mass. Modeling clay is made with mineral oil, which leaches out into the wood and causes all sorts of problems. The goo in poster adhesive pretty much stays put.

Re: tone and volume on top plate actual effect?

Posted: Thu Sep 20, 2018 9:04 am
by Brian Evans
Alan, thanks for that tip. I actually used mineral oil as the lubricant when wet sanding the water-based EM6000 finish, the wood (and my fingers) seem to like it, silky smooth... :) Mineral oil cut significantly with naptha.

Re: tone and volume on top plate actual effect?

Posted: Sat Sep 22, 2018 8:38 pm
by John Clifford
Don't know how pertinent this is to your inquiry, but I built this fully hollow carved archtop with the intention of making an electric guitar, with only enough acoustic sound to hear myself practice. That's pretty much how it turned out, but even with the thin body, maple top and hole-mounted electronics, it is still very prone to feedback. I found I could reduce the feedback somewhat by wedging a piece of dowel between the top and back (like a violin sound post), but it came loose and was too much trouble to fix, so I just took it out!