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An overly detailed saga:
I have had my Matt Cushman archtop since 2006. I love the acoustic sound of the guitar, the feel and playability are top-notch. It's been good enough that I have not seriously thought about buying another archtop since then. Not that I haven't been tempted by the odd Tal Farlow, vintage ES-175, Gibson or Heritage Johnny Smith, etc.
Then I go play the Cushman and that pretty much settles the temptation (my GB10 has the same effect, I might add). I'm sorry that Matt seems to have closed up shop, he really made a fine guitar.
However, I've always had problems with amplifying it. Part of that is the floater versus set-in pickup problem- and also having a carved archtop with a floater but really having the sound of the ES-175 with a P90 (i.e., 50s-early 60s Jim Hall) in my head. I have come to appreciate brighter sounds as I have gotten older, especially thanks to Peter Bernstein. While I was still trying to make the Cushman sound like a 1954 ES-175 I tried probably six different pickups on that guitar, not really being satisfied with any of them. Many pickups on that guitar have been downright shrill: the original Allparts mini-humbucker and a Kent Armstrong handwound PAF being the most noticeably so. Hum was always a problem, which also prompted pickup changes, putting copper shielding on the back of the pickguard, etc.. I modified a Gibson Classic 57 to be a neck-mounted floater which was the best compromise, but even that pickup still had a noticeable hum. My favorite sounding pickup was a Pete Biltoft humbucker-sized floating CC pickup with a Hum Debugger to manage the noise, but I went back to the Classic 57 because I just don't like having to have pedals. I want my pedalboard to be just a cord.
Part of the problem has been that there has always been a hum (usually 120 Hz rather than 60 Hz) in the guitar. I installed a string ground which did not completely solve the problem but helped. Recently, I got the bright idea to check whether the jack was wired correctly; I stuck my phone into the F hole and took pictures, identifying that the Mogami wire was soldered with white to hot and black to ground, which I was also using at the pots so that should have been fine. However, when I compared the photograph with the wiring diagrams for the Fishman jack, I noticed that the insulation around the foil shield had not been stripped to connect to the ground of the jack. So I pulled the jack out of the body, stripped the insulation and clamped down the strain relief around the foil shield. Put the guitar back together and the buzz was gone! Just blessed silence unless the tone pot was dimed, then there was a faint buzz. I also noticed that the string ground no longer has any effect.
That made me wonder if I could go back to the CC pickup and have less noise, so a few days later I swapped the pickups and controls. There is still just a trace of high frequency buzz, with the tone pot up much higher than I use it, but now some 60 Hz hum is noticeable which is manageable by careful orientation of the guitar to the amp. In the sweet spot, it is noise free. Amazing! As would be expected, there's more hum using my tweed Deluxe clone than there is using my AI Clarus 2r. I am so much happier with the sound, especially with the tweed- a big wide warm clear sound. Also, instead of installing the pickup to the end of the neck it's currently mounted to the body using a little bit of Blue Tack putty. I have a Hum Debugger that I had used previously with the CC, have not gotten that out of the box to give it a try yet but I expect that it will diminish the hum quite a bit, based on previous experience, so that I don't have to be so specific about positioning myself relative to the amp. However, given my rather allergic reaction to having pedals between the guitar and the amp, I may just go with careful positioning.
I thought about getting a power conditioner to reduce AC line noise, but I'm pretty sure it would have no effect since the amp does not hum when the guitar isn't plugged in. I think it is just interference from the power transformers getting picked up over the air.
Anyway, I thought I'd share this in case somebody else is chasing down a hum in their guitar that might be due to a simple oversight in wiring. This is my only guitar with Mogami wire; ungrounded the foil shielding was acting as an antenna. This particular version doesn't have a drain wire for the shield, so the foil has to be directly grounded at one end. I will admit I had come to think that shielded wire like this was snake oil, but when properly installed it works correctly and may make a string ground unnecessary.
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01-01-2023 03:05 PM
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I use the Electro Harmonix Hum Debugger to eliminate the 220 Hz. (I live in Germany) hum coming from somewhere that's picked up by my Peterson StroboStomp tuner when I use a clip-on mic to tune one of my acoustic instruments. They don't explain how it works, and I'm only just beginning to learn about electricity and electronics, anyway. It works great. However, I'm definitely not allergic to effects between my guitar and my amp and have more than you can shake a stick at; just not all connected at the same time. But to each his own.
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Thanks for sharing and glad to hear you solved it after all that time! Some of my guitars are hum-free with the volume at either 0 or 10 but they hum with the volume set in between. I never understood why some do that and some don’t.
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According to my very limited understanding of this, my guess would be that at 0, you've basically cut off the signal so no signal is reaching the amp, so the hum component of the signal isn't either. At 10, the amplitude of the desired part of the signal is so much larger than the hum component that the latter isn't noticeable. The hum is always there, as long as the conductor with the signal is within the magnetic field of some other conductor with an alternating current. It might be small, you might not hear it, you can compensate for it, you can mask it, you can filter it out, but it never really goes away.
Maybe someone who really understands this stuff will correct me if I'm wrong.
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That was exactly the case with this guitar; at 10 and at 0 or thereabouts, the 120 Hz buzz was gone. Of course at 0 so was all the sound. The buzz was worst about 8 or so on the rotation. The string ground helped as long as I had one hand down the strings and grounding myself. That all went away with properly connecting the shield between the volume pot and the jack. Note that this is apparently only supposed to be grounded at the far end at the jack, not at both ends. Now it's the low 60 Hz hum, which is loudest when the face of the pickup is pointing straight towards the amp, and almost completely absent when the neck is pointing towards the amp.
Originally Posted by Oscar67
Last night I pulled out the EHX Hum Debugger and gave it a try. It does suppress the 60 Hz hum pretty effectively, but to my ears it comes at a cost of making the tone a little more nasal and a little less rich. That could actually be my imagination. Pat Matheny uses one with his CC equipped guitars and doesn't think the tone is adversely affected at all. His ears are better than mine (or maybe not, given that he has spent a half a century standing on stage hundreds of nights a year playing concerts, and I haven't).
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It might not be your imagination. And it might not be adversely affected, in Pat Metheny's opinion, or mine, or anybody else's, but it's certainly affected somehow. EHX says the Hum Debugger isn't a filter, but they don't say how it works. However, it's removing something and it doesn't "know" the source of what it's removing, whether it's the hum or part of the desired signal. Originally Posted by Cunamara
I'm finding that in electronics, there are a lot of parallels to computer programming (my profession). Designing a circuit is a lot like writing a computer program. In fact, any computer program is really a just a simulation of an extremely complex electronic circuit, and if you wanted to, you could realize it using resistors, condensors, spools, etc. In programming, there's always a cost. Usually, it's either time or space. With audio, it's noise, or latency, or signal degradation, or whatever.
With AC, there will always be hum. On the other hand, the last place I worked manufactured electrical equipment (emergency lighting systems) and my colleagues liked to trade stories about their near-death experiences with DC current. An accident with AC is much less likely to be fatal. I try to remember that when I hear buzz or hiss or pops coming out of my amp.
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The way to find out what's happening is to use an oscilloscope. I've got one standing in my work room, but I haven't learned how to use it yet. One of the main reasons I bought it was to find out what my effects pedals do to the signal coming from my guitar.
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Thanks for sharing! Originally Posted by Cunamara
As i'm also tempted to try modifying a regular humbucker into a floater i'm wondering how you did it. Can you post some pics of the modified PU? TIA
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In my case, I started with a Gibson Classic 57. I cut the legs off and filed the cover down to be flush with the base plate, because there was not a lot of room between the top of the guitar and the strings. That was actually the easy part. One complication is that the pickup wire comes out of the wrong corner of the pickup if you want to mount it with the screw coil closer to the neck; facing the pickup head-on in that position, the wire comes out of the pickup at the upper left-hand corner. You could turn it 180° and have the screw coil closer to the bridge, a la Wes Montgomery, and then the wire would come out a much more convenient spot by the pickguard. It also comes out of the base plate rather than the side of the pickup; I painstakingly filed a little slot into the pickup cover so that the wire could come out of the pickup parallel to the top instead of perpendicular to it.
The hard part was figuring out how to mount it. I have a completely fact-free theory that the more the pickup is isolated from the vibration of the top, the stringier it sounds and the less woody. So if the pickup is mounted to the pickguard à la Benedetto, it is very much isolated from the top of the guitar. If it's mounted into the top of the guitar, like an L5CES, the pick up is immersed in the vibration of the top and the signal is much more complex going to the amp. I have not a shred of proof for this and it could be complete hogwash.
I didn't want to cut a hole into the top of my nice acoustic archtop guitar, in part because I didn't know if I would be cutting through the braces. So I made a bracket in a square U shape and mounted it to the end of the neck like a Johnny Smith pickup. This involved drilling three small holes into the cover and putting very short screws through the bracket into the cover and then epoxying the bracket on as well. In the process, I managed to touch the coil with the tip of the drillbit and ended up having to send the pick up off to Kent Armstrong to be repaired. He was very kind and refrained from calling me an idiot to my face. But he fixed it, I mounted the bracket to the pickup and the pickup to the guitar, and it worked pretty good. Tone-wise it was pretty easy to get into the Peter Bernstein area, which is not a bad place to be, but of course it still did not sound like an ES 175. And never will, since it isn't.
I would not do that mounting bracket now. A few years later, somebody here talked about mounting a pickup directly to the top of the guitar using Blue Tack 3M poster putty. What a brilliantly simple idea. I have taken to using that to mount the pickup to the guitar and it takes a matter of moments. I don't notice any change in the acoustic sound of the instrument. I think there is not a lot of flex to the top right there, since it's by the neck block; a pickup mounted into the top by the bridge probably has much more impact on the acoustic quality of the instrument. If there is a change in the amplified tone mounting it that way compared to floating it, it's pretty subtle and doesn't really support my theory very much. But who says you have to change what you believe in the face of facts and observation?
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As you can see, I mounted it on the bass side with three small brass screws. On the treble side, the pickguard mounting screws pass through the bracket and sandwich it.
The pickup is really too close to the strings and that makes it hard to balance, which probably also contributes to my less than complete satisfaction with the sound. There is about .010" between the underside of the base plate and center of the top of the guitar (I also had to trim down the polepiece screws). If I was to do this over again, I would talk to Peter Biltoft at Vintage Vibe Guitars. He could wind a humbucker with fittings for the bracket and a vertical dimension suitable to the available space under the strings, to allow for some range of adjustability. He did that with the Charlie Christian humbucker-sized pickup that he made for me, which has threaded brass bushings in the side facing the neck and machine screws to hold on the bracket. That's the pickup currently on the guitar although currently I'm not using the bracket and have puttied it to the top of the guitar with four pea-sized pieces of Blue Tack on the corners of the pick up.
Both he and Kent Armstrong were really great to deal with. They both seemed really interested in the project and helping to accommodate a solution and I wholly recommend doing business with either of them.Last edited by Cunamara; 01-03-2023 at 08:28 PM.
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Actually I think that Pete has a model like that which you can buy right off the shelf, a shallow floating hum bucker, though it attaches to the bridge. It might be possible to get one that attaches to the neck. I am having his floating minihumbucker mounted on my Campellone right now, interested to hear how it sounds.
I am very interested in your theory about attaching to the body or neck and how it affects the sound. I actually think that a floater is more complex, with more air and maybe harmonics in the sound, while a set pickup has stronger fundamental. But no lavish experiments to back that up!
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Biltoft makes a Johnny Smith type humbucker that attaches to the neck. It's not prominent on his website but he can make it. The problem with these is that it comes in one width for the attachment legs, and if it doesn't fit your guitar's neck, it will be a problem. I asked him if the legs would take the rebending necessary to fit a different width, and he said he thought they would. They won't. I ended up with a pickup that attaches with Blu-Tack, no legs left.
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Good to know. I had looked at buying a Lollar JS pick up and took a pass on it for that very same reason. I wasn't about to start carving wood out of the neck extension to make it fit and the Lollar folks were sure the bracket wouldn't tolerate any bending. When Pete made my HCC pickup, he installed four threaded brass bushings along the leading edge so I could fabricate and mount a bracket that fit the neck to the pickup using machine screws. He even sent me a drilling guide.
However, to be honest, using Blue Tack works just fine. I maybe wouldn't want to use it on a French polished or vintage nitro finish.
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They're right that the bracket won't tolerate any bending. Almost none. And the JS pickup doesn't sound that good to me, so it's been wasted money. Just this week I tried replacing the DeArmond Rhythm Chief with it, and it lasted about 5 minutes. I use Blu-Tack on the RC also, because I don't like to use a pickguard. The putty keeps it from flopping around the rod, doesn't take much.
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