SUCCESS: K&K Pure Mini SBT's with Taylor ES-T onboard preamp!

[joeguam]

After reading many threads on numerous forums, I'm hoping this info helps someone, somewhere as I was not able to find a straight-forward answer.

Here are the related threads which has more information on this modification:
Taylor ES-T preamp w/ K&K SBT piezos?
K&K pure mini installation on Taylor
Any successful Taylor ES-T mods?

On TGP:
Taylor ES-T pickup sound solution

In short, I had many problems (e.g. imbalance, quack) with the UST of the Taylor ES-T system in my 114ce and tried numerous proposed fixes from Taylor to resolve with no luck. So, here are the steps I took to test out the swapping of the Taylor UST/piezo with K&K Pure Mini SBT's but still routing the signal through the onboard Taylor ES-T preamp with volume/treble/bass controls so I didn't have to modify the structure of the guitar and could still reuse the preamp.

First, to test this at the cheapest cost possible, I used my wife's GS mini which has a K&K Pure Mini perfectly installed (I say perfectly because we love the sound it has when plugged in):



Then, I disconnected and removed the UST from my 114ce, soldered a splice from the 2.5mm jack to a regular 1/4" plug. You can see the UST in this picture with the cut wire lead and the 1/4" - 2.5mm splice:



I then reconnected the 2.5mm jack back into the 114ce ES-T onboard preamp - very simple as it's just a plug:



Lastly, I connected the GS Mini to the spliced cable and then the 114ce to my mixer/PA. Here is the signal chain:
GS Mini -> K&K Pure Mini -> Taylor ES-T Onboard Preamp -> Mackie 1220 -> JBL EON15



The result is a SUCCESSFUL solution!

I'll do a bit more testing, however, here are some initial findings:
- The signal into the ES-T preamp was much hotter than from the UST, so I had to back down the volume from the center detent at 12:00 to about the 9:30 position
- The signal into the ES-T preamp has much more bass than from the UST, so I had to back down the bass knob from the center detent at 12:00 to about the 7:30 position (slightly above zero)
- I had to boost the treble knob from the center detent at 12:00 to about the 3:00 position to get a bit more of the sound I'd prefer
- MOST IMPORTANTLY: The quality of sound of the K&K Pure Mini is bounds and leaps better than the UST!

Please share comments and suggestions, however, I'm so relieved that this worked!

Cheers.

...
Joe

[rschultz]

I have to say I'm IMPRESSED. From one solder geek to another, my hat goes off to YOU. Great work!

You could start your own business by making kits for people to buy and upgrade their crappy ES to your K&K solution. Come up with a catchy name and make a little money... to fund your hobbies

[rschultz]

Originally Posted by joeguam

I'll do a bit more testing, however, here are some initial findings:
- The signal into the ES-T preamp was much hotter than from the UST, so I had to back down the volume from the center detent at 12:00 to about the 9:30 position
- The signal into the ES-T preamp has much more bass than from the UST, so I had to back down the bass knob from the center detent at 12:00 to about the 7:30 position (slightly above zero)
- I had to boost the treble knob from the center detent at 12:00 to about the 3:00 position to get a bit more of the sound I'd prefer
- MOST IMPORTANTLY: The quality of sound of the K&K Pure Mini is bounds and leaps better than the UST!
Joe

You might be able to tweak the EQ by adding caps/resistors in series or parallel with the pots. I'm not sure what if anything would work, I don't have that kind of knowledge. But plenty of people do, so ask around.

[joeguam]

Hello Everyone,

I performed the same test using the GS Mini and a "jumper cable" to another instrument - this time a custom super concert ukulele - to determine it was possible to use a Fishman Matrix Infinity preamp with the K&K Pure Mini SBT's.

Here are the photos using the same configuration:





This one was much easier to wire up because the Fishman preamp has solder free terminals.

The result...IT WORKED!...and it sounds MUCH BETTER than both the Taylor ES-T preamp or the Fishman UST! This one didn't need any drastic EQ adjustment and the volume knobs work perfect!

I'm so glad I did these tests, looks like I'll also be purchasing the K&K Aloha Twin (SBT's voiced for ukulele) along with the Pure Mini for my 114ce.

Cheers!!!

...
Joe

[guitaniac]

The one problem which you might possibly encounter, Joe, is that the Pure Mini might overdrive the ES-T preamp, or the Infinity preamp, when you're strumming at your hardest. Its likely that both of those preamps have a fixed gain which is optimized for the pickup which the preamp is designed to work with.

Then again, you may not have a problem. Its easy enough to strum hard, while amplifying, to see if you hear any distortion (which would indicate that the preamp is being overdriven).

I only bring this up because I once had a tech install a Baggs LB6 passive pickup and wire it to the Fishman Prefix preamp in my Taylor. The result was severe distortion with moderate strumming. We ended up having to wire the LB6 directly to a strap-jack and using an outboard preamp with it.


I later learned that a film piezo pickup (like the Fishman film UST in the Prefix system) tends to put out a much weaker signal than a crystal piezo pickup like the LB6. The Prefix system's preamp had a fixed gain which was set relatively high to accommodate the weaker signal of Fishman's film piezo pickup, so the strong LB6 signal overdrove it. If it had been possible to lower the Prefix preamp's gain, it could have accommodated the LB6's stronger signal.

I eventually learned that it would have been possible to reduce the LB6's signal by wiring a proper sized capacitor across it, but neither myself or my tech have any expertise as to how to calculate the size of the capacitor needed.

[joeguam]

Was it a capacitor or a resistor that you learned of to reduce the gain? It is my understanding that a reduction of voltage is needed, so that would be a resistor right?

But I could be mistaken...

...
Joe

[moccaguitar]

thanks a lot for posting this - i' ll also do this with my 114ce. have a pure mini layin' around and also one in my mini hog , which i like very much. there must be also a switchable damping unit in my toolbox - i 'll try it to lower the output of the pure mini a bit.
i was never satisfied with the es-t, but the 114ce is a great guitar for the money.

thanks
moccaguitar

[joeguam]

Mocca, I'm in the process of adding a 1M Ohm resistor to the lead that plugs the SBT's into the Taylor onboard preamp. The GS Mini sounded so much better and almost perfect plugged into the Fishman Matrix Infinity preamp, so I'm determined to find a fix to the excessive bass through the Taylor preamp.

I'll post my results when it's finished.

...
Joe

[joeguam]

Here's the latest:

I was very satisfied with the sound produced by the K&K SBT's through the Fishman Matrix Infinity preamp so no further tests will be required. If you have a Fishman Matrix infinity preamp and are thinking of swapping the UST for K&K Pure Mini SBT's, my official recommendation is to proceed as the sound is significantly better.

Now with the Taylor ES-T onboard preamp, there's still a bit of work needed before I can be comfortable with the sound produced when plugged in. I did a couple of tests tonight using the same setup with the 114ce, the splice cable and the GS Mini. Here are the results:

Signal Chain: GS Mini -> K&K Pure Mini -> BOSS TU2 -> Taylor ES-T Onboard Preamp -> Mixer/PA
Comments: I added the BOSS TU2 as some have claimed it has an impedance match to the K&K SBT's, however, I didn't notice one bit of difference with or without the BOSS TU2 pedal in the signal chain.

Signal Chain: GS Mini -> K&K Pure Mini -> Venue DI -> Mixer/PA
Comments: I did this preliminary step as the first part of an A/B test. I wanted to see how good I can get the sound with just a Venue DI. Surprisingly, I still had to cut the mids and lows a bit to get the natural sound I was after. The input impedance of the Venue DI is listed in the manual as 10MOhms, so this effect may be similar to what is happening with the Taylor ES-T.

SUCCESSFUL SOLUTION #1: Signal Chain: GS Mini -> K&K Pure Mini -> Taylor ES-T Onboard Preamp -> Venue DI -> Mixer/PA
Comments: There was no significant difference here when adding the Taylor ES-T preamp before the Venue DI into the signal chain. The signal was still very hot and I needed a lot of bass and mid cuts. The only added benefit here is that the Venue DI has a 5-band EQ and allowed me to attenuate the proper frequencies enough the achieve the natural sound I was after. At the very least, if I was playing a gig with only a guitar (my P&W gigs), this is a successful configuration.

SUCCESSFUL SOLUTION #2: Signal Chain: GS Mini -> K&K Pure Mini -> Resistor (1MOhm??) -> Taylor ES-T Onboard Preamp -> Mixer/PA
Comments: I added a resistor that I had laying around to the 2.5mm / 1/4" splice cable, which essentially reduces the impedance and voltage of the signal outputted by the K&K SBT's into the ES-T preamp. Here is a picture of the resistor, my only problem is that I'm not sure of the resistance measurement of this particular resistor because I can't make out the colors of the bands. It was taken from an input jack from an old pedal so I'm assuming its a 1MOhm resistor that was used as a pull-down resistor to rid of the pop. Please excuse the soldering job, this isn't my best work and is messy, but it's just the testing phase.



The result of this configuration is that the overall signal was attenuated noticeably. The mids and bass tamed down just a bit, but not quite enough. At the lowest bass knob setting, i still needed to boost the treble knob, to balance out lows and mids to a comfortable level - but it worked. It's not the ideal configuration, but it works. I did have to increase the volume knob to get the same level as before the resistor was added. Ultimately, if I had to do a guitar-only gig, this is a successful configuration.

But I don't want to stop until I get it perfect!

So, my next steps is to order a series of resistors - 1M, 2M, 5M, 10M, 20M - and test each one in the signal chain until I'm satisfied with the level of attenuation of the signal into the ES-T preamp. Once I get the correct level, I'll have the perfect blend of signal and can use the onboard bass/treble/volume knobs as it would normally be used to dial in to the natural sound of the K&K pure mini that I'm trying to achieve. One thing I do know for sure, I'm SUPER HAPPY that I will NEVER have to deal with the headaches of an under-saddle pickup every again!

Please share your comments, suggestions or thoughts AGF, it's more than welcomed. I don't think I'll have another update for a week or 2 as I'll have to wait for the K&K SBT's to arrive in the mail, as well as the resistors. But I promise to post the final update of my testing in hopes that this will help someone who wishes to do something similar.

Cheers!

...
Joe

[andyhill]

In case of interest to anyone. I have just purchased and tried out the jjb electronics pick up. (See link) which comes with a 2.5mm jack and can plug straight into existing on board preamps. (There is a note on the site about impedance matching)

I have nothing to do with the company at all but am sharing this because the sound quality is better than the sound hole pick I paid over £100 for.

In my view this is really worth a try. You might think that at the price it wont be good quality but you might be very surprised as I was. You have to play about with the eq and turn the bass down significantly but the clarity is very good as is the sustain - in part it sounds very realistic.

http://jjb-electronics.com/PPS-200P.html

Hope this is useful to someone.

Thanks

Andy

[guitaniac]

Originally Posted by joeguam

Was it a capacitor or a resistor that you learned of to reduce the gain? It is my understanding that a reduction of voltage is needed, so that would be a resistor right?

But I could be mistaken...

...
Joe

The old Baggs Hex pickup kits included two capacitors. You were supposed to wire in the appropriate capacitor (in parallel with the pickup and the preamp inputs), depending on which of the two Baggs onboard preamps (the LB6-specific preamp, or the ribbon transducer-specific preamp, which they were selling at the time) you were wiring the Hex to.

Baggs doesn't sell the Hex system anymore, but I have it in one of my classicals. I use it with the Fishman Platinum outboard preamp, and it definitely does put out a whopping big signal, too big for either the LB6-specific preamp, or the ribbon transducer-specific preamp, which Baggs was selling at the time.

FWIW, I DO think that wiring a 1MegaOhm resistor in parallel with the Pure Mini (and the ES-T preamp input) might reduce your bass. (It would reduce your total input impedance to less than 1MegaOhm.) On the other hand, I recall that a temporary install (with double-sided tape) of the Pure Mini in my Taylor 314c was EXTREMELY bassy. It may just be a problem with the construction of some Taylors not being terribly compatable with the Pure Mini, or it may be that a permanent (glued) installation wouldn't have been so excessively bassy. I ended up gluing the Pure Mini into a cheap Samick OM, with much better results.

[joeguam]

Thanks guitaniac for the info.

I was actually able to determine that the resistor I added into the spliced cable is 100K Ohms and not 1M Ohms. This would explain why the attenuation of the signal wasn't so drastic, although noticeable.

While I wait for the 1M Ohm resistors to arrive in the mail, I'm picking up a potentiometer today to add into the spliced cable instead of the constant resistor. This can at least allow me to increase the resistance (lower the impedance) of the signal slowly to see if 1M Ohm resistor is even required.

The unknown in this circuit is the input impedance of the Taylor ES-T preamp, anyone have any ideas on how to determine this spec? I called Taylor and the tech I spoke with had no idea - which I find ridiculous.

I'll post my results of the potentiometer test as soon as I complete it.

...
Joe

[joeguam]

Here's the latest in this quest to rid of under-saddle transducers forever, I added potentiometers (pots) into the cable splice to attempt to reduce the input impedance and it worked beautifully. For those who are not familiar (like I was a day ago), a pot is essentially a resistor that allows you the ability to increase or decrease (variable) the amount of resistance in the circuit. The most common pot is the volume knob on your car stereo.

Here is a picture of the configuration, nothing's changed in the 2.5mm / 1/4" splice cable, only add 2 resistors in series (R = R1 + R2) from signal to ground. The pots are 250K and 500K Ohms, not quite 1M Ohms but significant enough.



The result of this test is a perfect configuration using the following signal chain:
GS Mini -> K&K Pure Mini -> 750K Ohm Resistor -> Taylor ES-T Onboard Preamp -> Mixer/PA

This time around I had to actually bring the bass EQ knob up to the center detent!!! For a song which I loop the bass line, I had to actually bring it past the center detent! I still think a 1M Ohm resistor would be better suited and allow a bit more control, however, at least I know that 750K Ohms works just fine. I tested a really hard strum and also increased the gain at the mixer to try and invoke distortion...NONE!

So my testing will end here with a huge grin on my face that I was successful in this modification and I'll never have to deal with under-saddle transducers ever again. Even more satisfying is that I can enjoy and use the K&K Pure Mini pickup - the sound I'm very pleased with - in gigs now. The next post will be when the K&K Pure Mini and the 1M Ohm resistors arrive in the mail and I have the final modification to my 114ce done - which may include upgrading the Taylor TUSQ saddle to a Bob Colosi bone saddle.

Cheers AGF!

...
Joe

[andyhill]

Hi Joe,
Very interesting to see this. I wonder if the mids and high freqencies are affected by adding the resistors, would you commenting on this. Thank you.
Andy

[joeguam]

Andy, there are folks that may correct me, however, with my knowledge of electrical circuits, a resistor reduces the electrical current - but not at specific frequencies. As a result, the resistor reduces the electrical current (and increases impedance) of all frequencies, not just the lows and mids - essentially reducing the overall level/gain of the signal from the transducers as well.

The way I understand this as is also apparent from my testing, is that the resistor essentially reduced the level of all frequencies from lows-mids-highs. Because I first added a small resistor, 100KOhm, I noticed the reduction of signal was only minimal. After adding the pots and slowly increasing the resistance by turning the knobs, it was an evenly reduced signal of all frequencies.

Now I had to adjust the bass/treble knobs to make EQ adjustments according to my preference, however, there is nothing that could be done about this because I opted NOT to remove the Taylor ES-T onboard preamp and instead reuse it. The Taylor ES-T preamp has been specifically voiced for their under-saddle-transducer, which has a very different frequency output than the K&K soundboard transducers. IMHO, there is not even the slightest doubt that the K&K SBT's are bounds and leaps better in tone and sound quality than the Taylor UST.

In short, without the resistor, the output from the SBT's are real hot at all frequencies, however the lower frequencies overdrive the Taylor onboard preamp (this is the muddy boominess). By adding the resistor, I'm able to reduce the signal to a level which does not overdrive the preamp and allows me to increase/decrease specific frequency ranges (using the bass or treble knobs) to obtain the specific sound I'm after. The other option is to use a strong-enough EQ to just cut each specific frequency individually - which is what I did with the Venue DI in one of my tests described earlier in this thread.

Once I receive the parts in the mail and finish the installation, I'll try to post a video so you can all hear the sound.
Hope this helps!

...
Joe