Under-saddle to Soundboard Pickup conversion

[engblom]

After many hours of trying to find a smaller affordable nylon stringed guitar with 14th fret body and cutaway without an under-saddle pickup I have given up. The Cordoba Mini II with cutaway would be perfect, except for that it got an under-saddle pickup.

If I would buy it, I would like to do the following:
1. Cut the wire coming from the pickup.
2. Remove the under-saddle pickup. Probably the saddle would be too low now, so I would replace it too.
3. Solder 3 piezo discs in parallel to the pickup cable I cut in step 1.
4. I would glue the discs to the soundboard.

Thus the original preamp would be in use, but with other transducers. Would this work? Would it sound OK?

(In case someone wonders why I do not want under-saddle pickup: I play 99.95% just acoustically and I do not want anything to dampen the sound between saddle and bridge.I am a very light finger-picker. Also if I would plug it in I would want it to sound like it was played acoustically, I want the vibrations from the soundboard, not the saddle)

[Mbroady]

Might be an impedance mismatch. if I had to guess, the preamp in the guitar would have a higher impedance then sound board transducer discs, resulting in a bass heavy sound. If the preamp has built in EQ then you could adjust accordingly. I've done what you are thinking and it worked out ok.

[Rudy4]

Originally Posted by engblom

After many hours of trying to find a smaller affordable nylon stringed guitar with 14th fret body and cutaway without an under-saddle pickup I have given up. The Cordoba Mini II with cutaway would be perfect, except for that it got an under-saddle pickup.

If I would buy it, I would like to do the following:
1. Cut the wire coming from the pickup.
2. Remove the under-saddle pickup. Probably the saddle would be too low now, so I would replace it too.
3. Solder 3 piezo discs in parallel to the pickup cable I cut in step 1.
4. I would glue the discs to the soundboard.

Thus the original preamp would be in use, but with other transducers. Would this work? Would it sound OK?

(In case someone wonders why I do not want under-saddle pickup: I play 99.95% just acoustically and I do not want anything to dampen the sound between saddle and bridge.I am a very light finger-picker. Also if I would plug it in I would want it to sound like it was played acoustically, I want the vibrations from the soundboard, not the saddle)

Electronically I believe it would work fine. It probably wouldn't sound much different than the undersaddle, and most likely not as good. Cordoba is keyed into making lower tier nylons with acceptable tone, so that undersaddle is no accident. They would put double or triple transducers on the soundboard if their research bore that out as a good way to get a good sounding electro-acoustic nylon strung guitar. If they brace the Mini like all their other guitars you can't use triple transducers because the center brace is where you would normally put the center transducer. You can get JJB double transducers for $50, so they are cheap enough.

I've been experimenting with soundboard transducers in my Cordoba Cadette and it's not a good option so far. There's a reason why all these new electro-acoustic nylon strung guitars like the Ibanez and the Cordoba Stage start out with an under saddle; it's one of the better options for nylon strings and doesn't have near the problem with quack and harsh tone that steel string undersaddles do.

If you're really going after tone but want a smaller instrument I can highly recommend the Cordoba Cadette, which is a 3/4 size acoustic. The Mini has a really small body and sub-22" scale length that's going to sound very toy like. The undersaddle pickup will be the least of your worries if you are looking for good nylon tone. The tiny plywood soundboard and extra-short scale length will strip off most of what you're looking to hear. Another $200 will get you in Cadette territory, and it has a great tone that is deep and resonant WAY past what I thought a 3/4 size could sound like.

I have a review of the Cadette posted here on AGF. I've been playing seriously for 60 years and it's a great smaller nylon strung acoustic.

Perhaps the Mini II is what you want, though.

[guitaniac]

FWIW, the spruce top model has a solid top and the scale length is 22&7/8”.

Beyond that, I pretty much agree with Rudy that the undersaddle pickup will sound better than a soundboard pickup (by itself). On the other hand, adding a bit of soundboard pickup signal to the UST signal can sound nice. I do this with my own thin-bodied nylon stringer (Baggs Hex pickup plus Schatten Design Dualie).

It’s worth noting that smaller, less resonant guitars tend to make good modeling platforms. My own nylon stringer is the best platform I have for using my Zoom A1-Four’s mild modeling. It also works well with the old Fishman Aura blender’s classical guitar sound image. If you can find one of those Fishman Aura pedals with 16 nylon string guitar sound images, there’s a high likelihood that one or more will sound good with the Mini II (with the stock UST).

Rudy is spot on about the fan bracing construction of the Mini II’s top. That’s why the K&K Classic system has four sensors, although two sensors would likely do the job nearly as well. Even my one piece Dualie (placed on the treble side of the center brace) works fairly well. It just doesn’t provide the string separation and definition of the Hex.

Mixing and matching pickups with preamps is a dicey undertaking, but it would likely work as the SBTs are likely to have a somewhat weaker signal than the UST they are replacing. (Won’t overdrive the preamp.)

If you go through with the alterations which you are planning, it’s possible that it will improve the guitar’s acoustic tone a bit, if that’s the primary goal. It’s a lot less certain that you’ll improve the amplified sound and it’s almost a given that you’ll reduce that guitar’s resale value.

[engblom]

Originally Posted by Rudy4

If you're really going after tone but want a smaller instrument I can highly recommend the Cordoba Cadette, which is a 3/4 size acoustic. The Mini has a really small body and sub-22" scale length that's going to sound very toy like. The undersaddle pickup will be the least of your worries if you are looking for good nylon tone. The tiny plywood soundboard and extra-short scale length will strip off most of what you're looking to hear. Another $200 will get you in Cadette territory, and it has a great tone that is deep and resonant WAY past what I thought a 3/4 size could sound like.

Than you for your insights. I am not set on a Mini II and I am open for suggestion, but Cadete would not work for me. In my first post I did not tell why I want the body at 14th fret instead of 12th fret and why I would want a cutaway. The reason is that I have been playing almost entirely in Open D tuning, often making bar chords high up the neck so I can mix in melody with the chord. I also have a dreadnought acoustic without cutaway and so many times the lack of cutaway has caused problems. I decided that the next guitar will be both nylon (I like the sound of nylon better) and with a cutaway. Thus I need some kind of crossover guitar.

While my playing style benefits from shorter scale length (because then I better reach far away frets while playing a bar chord), I hope to not sacrifice too much of the sound. I am also worried the tension would be too low for Open D tuning because a shorter scale length will cause lower tension.

Most of the time I will play it unplugged at home for own fun, but I might use it at the local church a couple of time a year. Because I am a very light finger picker, those times I will need a slight amplification and any amplification method is OK as long as it does not take the joy out of playing it unplugged at home. I have been afraid of under-saddle pickups because of this.

[engblom]

Originally Posted by guitaniac

If you go through with the alterations which you are planning, it’s possible that it will improve the guitar’s acoustic tone a bit, if that’s the primary goal. It’s a lot less certain that you’ll improve the amplified sound and it’s almost a given that you’ll reduce that guitar’s resale value.

For me the acoustic tone is the most important. If I could find an affordable pure acoustic nylon with a cutaway and 14th fret body I would buy it straight a way. I would prefer to have no built in electronics at all. It is always possible to add external pickups to a pure acoustic.

The modifications I was thinking about would be to put the existing electronics to some use, but I am afraid to ruin the guitar and you are right the value would be reduced. I was also hoping it would give a bit of more natural sound because when I have listened to the sound samples of the under-saddle pickup I have not been impressed.

All advice are welcome!

[engblom]

Originally Posted by Mbroady

Might be an impedance mismatch. if I had to guess, the preamp in the guitar would have a higher impedance then sound board transducer discs, resulting in a bass heavy sound. If the preamp has built in EQ then you could adjust accordingly. I've done what you are thinking and it worked out ok.

I was also thinking about this impedance mismatch and I do not have the knowledge of the difference in impedance between the two types. The Mini II got an EQ.

[Rudy4]

Originally Posted by engblom

Than you for your insights. I am not set on a Mini II and I am open for suggestion, but Cadete would not work for me. In my first post I did not tell why I want the body at 14th fret instead of 12th fret and why I would want a cutaway. The reason is that I have been playing almost entirely in Open D tuning, often making bar chords high up the neck so I can mix in melody with the chord. I also have a dreadnought acoustic without cutaway and so many times the lack of cutaway has caused problems. I decided that the next guitar will be both nylon (I like the sound of nylon better) and with a cutaway. Thus I need some kind of crossover guitar.

While my playing style benefits from shorter scale length (because then I better reach far away frets while playing a bar chord), I hope to not sacrifice too much of the sound. I am also worried the tension would be too low for Open D tuning because a shorter scale length will cause lower tension.

Most of the time I will play it unplugged at home for own fun, but I might use it at the local church a couple of time a year. Because I am a very light finger picker, those times I will need a slight amplification and any amplification method is OK as long as it does not take the joy out of playing it unplugged at home. I have been afraid of under-saddle pickups because of this.

Fair enough. I play a 14 fret steel strung for much the same reasons, often capoed as high as the 7th fret.

As far as scale length goes I usually have the Cadette in dropped D and also play it in CGDGBE tuning. It handles the ultra-low tension well, even at it's 24" scale length.

[Mbroady]

Originally Posted by engblom

I was also thinking about this impedance mismatch and I do not have the knowledge of the difference in impedance between the two types. The Mini II got an EQ.

Impedance could be an issue, but after reading some of the responses I suggest you try taking the UST out (but don’t disconnect it, just leave it in the body of the guitar). Then put in a new saddle that gives you the string action you want. listen to see if you can really hear the difference. Some times, on some guitars you might not notice a difference.

As mentioned, on a nylon string instrument in that price range the UST might work better for those moments you do plug in.

[alohachris]

Aloha,

Using ANY kind or brand of pickup alone will never give you a natural acoustic LIVE sound at gigs - especially using UST's. So congrats on your decision to convert to an SBT. But, you need a mic in your Live mix for many reasons, not the least of which is how much more fun it is to PLAY the acoustic guitar when it sounds natural. UST ear fatigue is a real thing, for audiences & the player too.

However, combining an SBT (K&K or Dazzo's are the best) with an internal condenser mic (DPA, Audix, AKG, AT, Countryman, etc.) in a dual source system can produce a MUCH more natural acoustic LIVE result.

NOTE: The key to controlling & maximizing the blended sound of the two sources is investing in a GREAT PRO LEVEL live blending preamp so you can EQ the sources separately. So I would lose your current onboard UST's preamp & get a great external preamp (like below) that will work with the impedance of whatever SBT you're installing, whether it's "hot" or not. What SBT are you installing?

Do the homework first on whether the preamp & pickup spec's allow for the type of pairing with you're new SBT.

Do NOT cheap out on the preamp. Too many players do & never get to fully control or maximize their Live signal chain. Go with something like the Grace Designs Felix2 Live Dual-Source blending preamp. Most of the pre's on the market do not maximize your gear in a variety of venues. The Felix2 will.

https://www.sweetwater.com/c979--Aco...E&gclsrc=aw.ds

You'll get more natural sounding, crisp trebles by rolling off most of the bass & lower mid's on the mic channel EQ. You get presence & nice round bottom by rolling off most of the trebles & upper mids on the SBT P/U channel EQ. Then you blend them to taste & the requirements of the venue.

Dual-source systems with a mic & SBT combo is THE way to go, through a stereo endjack out through a great blending dual channel preamp, for steel-string or nylon guitar.

Or combine a K&K classical, four-pod pickup SBT system with a great internal condenser mic. Or use one of their mic's.

Of course, if you are playing solo in a great room, a guitar will sound best amplified LIVE when played through a good external SDC mic alone. I always used that when I played smaller, 'safer' intimate gigs like upscale, intimate restaurants. Nylon strings especially benefit the most from playing though a good single external mic alone in ideal venues.

Sometimes, I would even add an external mic to the K&K P-U/AKG416 internal mic dual source systems I had in all my gigging guitars. Sounded VERY natural & FULL.

Note: The VERY helpful AGF veteran Guitaniac's ears will always tell you that UST's are the answer to every acoustic guitar live. Especially if it's controlled by the electronics in a trap-door. But I say, if you want an electric sound with electric type controls, then play an electric guitar! And avoid the quack! It's probably because what was most important when he engineered all those open mic's was to be able to set up & dial-in fast w/o feedback of newbie players, & KISS, Ha! Couldn't have had anything to do with that typical quacky, unnatural UST sound, right? Just kidding Guitaniac! Ha!

Good Luck!

alohachris

[alohachris]

Aloha,

Here's how to stereo wire a P/U - Internal Mic dual-source system, courtesy of Doug Young.

https://dougyoungguitar.com/blog/blo...l-mic-to-a-k-k

alohachris

[Doug Young]

I don't know that guitar, but I have done basically this, and others here have, too. The main issue is that you're embarking on an unknown. It's like deciding to put Chevy brakes in a Ford. Will it work? Maybe, maybe not. However, in that case, you can probably get all the specs, designs and so on to see if the parts will fit. Here, you don't know. You're unlikely to get the specs or the circuit diagram for this preamp, so that even if you knew lots about electronics, you'd still be guessing. As long as you're willing to be in mad scientist mode, full steam ahead :-)

Among the possible issues, I'd rate the impedance issue very low. In spite of what people say, I've yet to hear an example of an actual bass boost from a higher-than-expected impedance, and I've used K&Ks with everything from around 500K to 20M with zero issues. What a high impedance does with K&Ks is a more complicated discussion, but beside the point - I don't think that will be an issue.

But you don't know to what extent the preamp in the guitar was designed to work with the UST. It may have an EQ curve tailored for the UST. Maybe that will sound good with your SBTs, maybe not. Another concern is gain staging. K&Ks (I assume that's what you're talking about) are very hot, and if the preamp doesn't have enough headroom, it might overdrive the input stage and distort.

In any case, as long as you're careful and can re-install the UST, it's worth a shot, no way to really know without trying. I used K&Ks with the DTar Wavelength preamp for quite a while and that made a very nice (and *very* hot) pickup system.

[guitaniac]

Hi engblom,

Just looking at the undersaddle transducer will be helpful in giving you a clue as to whether or not the soundboard pickups might overdrive the preamp. Undersaddle pickups which employ six ceramic crystals will almost certainly have a stronger output than any soundboard pickup(s). Film piezo pickups will have a much weaker output and will require much more gain from a matching preamp. It’s possible that a strong soundboard pickup could overdrive a preamp which is designed to accommodate a piezo film UST.

At one time I had a guitar which was equipped with a passive K&K Pure Mini and a passive David Enke (piezo film) UST. They both required about the same amount of gain from an outboard preamp.

FWIW, I’ve also noticed that the Enke piezo film #26 soundboard pickup (available from Open To Source Sensors) has a much weaker output than the Pure Mini. If a Pure Mini did happen to overdrive your guitar’s onboard preamp, a #26 (which is adhered with double sided tape) would be much less likely to.