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mistermikev

mic inside semi hollow guitar

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so... I'm thinking ahead... perhaps dreaming.  at some point I'm going to build a fretless bass.  I'd like to do it almost fully hollow but probably only 1.5" thick.  don't really want to spend the money on ghost saddles because it is really a one trick pony for me.  something I'll probably only occasionally use. 

could do a ribbon/rope under saddle... but then you almost have to have a removable piece behind it as you are eventually going to mess with the saddle and potentially break the piezo.

mic inside the body?

I've built a few mics... the pimped alice for instance, and it is a fantastic sounding mic.  def compared well to several commercial mics I have.  Sounds fantastic on acoustic altho shock mounting in a guitar might be problematic. 

there are lots of schems on the net for electret capsules which would handle the shock mount issue.  I suspect the gain would have to be jacked way up to get any decent sound so...perhaps it'll be noisy.

obviously this would be something where I'd want to do a proof of concept... and I think at some point I'll probably build something and stuff it inside a semihollow guitar to see but was just looking for a thumbs up/down - feasible?  any experience with how it might sound? 

I know frank zappa def toyed with piezo disks in a guitar... no idea how that sounded.  what about a ribbon/rope piezo epoxied into the top of a semihollow - close to the neck so it'd get max string vibration?

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14 hours ago, mistermikev said:

could do a ribbon/rope under saddle... but then you almost have to have a removable piece behind it as you are eventually going to mess with the saddle and potentially break the piezo.

If you use a bridge similar to what's used in acoustic guitars, i.e. a bone bridge in a slot, a ribbon under the bone should be easy enough to be replaced if needed. After all there's a hole at the end of the slot and you'd also need to have a hole for the jack. Pushing the cord of the ribbon inside the instrument and catching it with a long hook shouldn't be too difficult.

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11 minutes ago, Bizman62 said:

If you use a bridge similar to what's used in acoustic guitars, i.e. a bone bridge in a slot, a ribbon under the bone should be easy enough to be replaced if needed. After all there's a hole at the end of the slot and you'd also need to have a hole for the jack. Pushing the cord of the ribbon inside the instrument and catching it with a long hook shouldn't be too difficult.

right on... thank you for the reply. 

I see a few issues with that. 

one - I have a few acoustic guitars with undersaddle piezo.  I have had to replace the piezo on one of them as twice yearly I have to put in my summer/winter saddle... and I'm pretty gentle with it.   that's not really an issue on an acoustic as you have room to get inside there... but on a thinline electric that would be impossible unless you had some sort of access hatch on the backside... and that hatch would have to be in an area I'd prefer not to have it... right under the bridge.  

two - the under saddle types tend to be very bright. I can't help but think (esp on a bass) it'd be nice to capture more of the center of the guitar.  I know that part of the guitar is exactly what I'm after when I mic it.

three - I'd really like to be able to adjust action/intonation. 

four - just not sure the look would be right for the guitar in mind. 

 

it's def a good fallback point... and if my testing doesn't go well I can always revert to that... but I've done more than my share of playing with piezos for elec drums and I think there might be some potential there that is unexplored.  If that doesn't work... an electret mic in the body might be pretty cool for getting closer to that 'upright' sound from a semi-hollow-body bass.

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i'd try something like this perhaps.....

https://www.ebay.com/itm/5-Band-Acoustic-Guitar-Preamp-EQ-Equalizer-Piezo-Pickup-Amplifier-Tuner-LCD-Mic/192007678265?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

 

you could also mount a couple of condenser piezo discs near the bridge inside the body, and wire them to the preamp listed above similar to a cigar box guitar.   the sound would be less bright than your typical bridge bar compression piezo.

Edited by norm barrows

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On 2/11/2020 at 4:16 PM, norm barrows said:

i'd try something like this perhaps.....

https://www.ebay.com/itm/5-Band-Acoustic-Guitar-Preamp-EQ-Equalizer-Piezo-Pickup-Amplifier-Tuner-LCD-Mic/192007678265?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

 

you could also mount a couple of condenser piezo discs near the bridge inside the body, and wire them to the preamp listed above similar to a cigar box guitar.   the sound would be less bright than your typical bridge bar compression piezo.

I have the schem for a 1970s ovation preamp that I will likely etch/build using metal film resistors and quality electrolytics..  I have used/tested cheap chinese stuff like that before and what you are going to get is a whole lotta noise.  plus the issue of two gargantuan boxes... just doesn't appeal to me but I appreciate the suggestion.

the issue with piezo disks is that they have a very small proximity.  I've got a lot of experience using them to build electronic drum kits and my intuition says that on a thinline style build... there probably is going to be issues getting sufficient level.  That means building a booster and boosting levels... but that adds noise and soon you are looking at adding filters.  Perhaps if I put them right under the bridge... but then this is going to sound very treble strong. 

going to have to try some experiments.  perhaps a combo of piezo ribbon/rope/disks and a condenser mic capsule... but then the electronics are getting more complicated and that's ok... but it will soak batteries fast and that's not ok.

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12 hours ago, mistermikev said:

  I have used/tested cheap chinese stuff like that before and what you are going to get is a whole lotta noise. 

my electrified fender acoustic has no noise issues. and its a similar unit.

if the chinese stuff is junk, buy the real mccoy.

 

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6 hours ago, norm barrows said:

my electrified fender acoustic has no noise issues. and its a similar unit.

if the chinese stuff is junk, buy the real mccoy.

 

welp... I did say "cheap chinese" not necc all chinese.  some chinese stuff is great. 

i digress.  I'm comfy building something like that from scratch and I enjoy it... but the focus of my thread is less about finding something to use and more about what is going to work well in the context of a thinline style build without spending $500 on ghost saddles given I'll probably use it every now and then.

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I'm pretty sure my Traveller just uses a plain old bar piezo. there's no preamp. and it sounds just fine.

as for mounting, you can mount it in a channel in the bottom of the bridge, or a channel in the body under the bridge.

for my stained wood piezo build, i'm going to try mounting it in the center gap of the archtop roller bridge first, then in a channel carved into the bottom of the bridge second. i'm going to see if i can build the entire  guitar without any holes or routing in the body other than the neck pocket.  IE just a big solid slab.  it only has the piezo, so you wont see any pickups or controls or covers at all anywhere. just an archtop bridge and tailpiece, with a 1" long piece of wire running under the 6th string from the bridge to the tailpiece (the piezo wire). the jack plate will be attached to the very end of the tailpiece.   dark walnut stained body, neck, and headstock, gold hardware, gloss acrylic finish. I put the neck on 2 days ago. need to dig up a gold jack plate from my parts box.  i've started buying generic stuff like jacks, jack plates, strap locks, strap buttons, by the dozen.    but right now i'm playing with the action and relief on the red guitar.

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13 hours ago, norm barrows said:

I'm pretty sure my Traveller just uses a plain old bar piezo. there's no preamp. and it sounds just fine.

as for mounting, you can mount it in a channel in the bottom of the bridge, or a channel in the body under the bridge.

for my stained wood piezo build, i'm going to try mounting it in the center gap of the archtop roller bridge first, then in a channel carved into the bottom of the bridge second. i'm going to see if i can build the entire  guitar without any holes or routing in the body other than the neck pocket.  IE just a big solid slab.  it only has the piezo, so you wont see any pickups or controls or covers at all anywhere. just an archtop bridge and tailpiece, with a 1" long piece of wire running under the 6th string from the bridge to the tailpiece (the piezo wire). the jack plate will be attached to the very end of the tailpiece.   dark walnut stained body, neck, and headstock, gold hardware, gloss acrylic finish. I put the neck on 2 days ago. need to dig up a gold jack plate from my parts box.  i've started buying generic stuff like jacks, jack plates, strap locks, strap buttons, by the dozen.    but right now i'm playing with the action and relief on the red guitar.

 welp... you can use a piezo with no preamp but IMO it'll sound a lot better with one.  also low impedance so depending on what you send it too, may sound like dog poo.  On top of that, for me, it's going to be combined with magnetics so mixing it without any pre is going to suck tone from the mags. 

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