James May Ultra Tonic/Tone Dexter Demo

AeroUSA · #1 03-01-2018, 07:22 AM

Just uploaded a video of the Ultra Tonic pickup (also features the Tone Dexter preamp).

Please subscribe. More coming!

https://youtu.be/ze3prRihJN8

guitaniac · #2 03-01-2018, 08:33 AM

Excellent demo. I especially liked hearing the dry, flat EQed sample and appreciated the fact that you provided both strumming and picking samples. Those dry and flat samples definitely sounded very well-balanced, with respect to tone, to my ears. It was also impressive to me that I didn't hear any quack from the directly recorded strumming samples.

I'd still be curious to hear how the pickup will act in a high amplification environment where that out-of-phase (anti-feedback) sensor is being put to the test.

open-road-matt · #3 03-01-2018, 08:41 AM

Nicely done Aaron!

Did you do the install of the pickup yourself?

Matt

Petty1818 · #4 03-01-2018, 10:26 AM

I love the concept of this pickup but I really wish that there was a way around the super glue method. I totally get why it's used but I just don't like it. It's unfortunate because I probably would use the K&K or Ultra Tonic more if they had a different adhesive.

gfirob · #5 03-01-2018, 10:52 AM

Great to hear another Tonedexter demo. Is the James May Ultra Tonic basically a K&K only better? Same design and concept with additional circuitry?

martingitdave · #6 03-01-2018, 11:28 AM

Based on Aaron's testing the past few weeks, I ordered an UltraTonic (K&K conversion) kit from James. It arrives today and I will be installing. It is not an uncomplicated install process. But, I have decided it that it will give me the "best" unplugged tone I can get from pickup that won't ruin the acoustic tone of my guitar. I like K&K, but this new pickup really addresses the weaknesses of the K&K, specifically low end "mud" and weak high e string balance.

I haven't mentioned anything because I promised not to steal his thunder on AGF. But, the cat is out of the bag now. ;-)

martingitdave · #7 03-01-2018, 11:36 AM

Quote:

Originally Posted by gfirob

Great to hear another Tonedexter demo. Is the James May Ultra Tonic basically a K&K only better? Same design and concept with additional circuitry?

James will probably chime in, but the circuit is passive. Basically, K&K suffers from feedback because it picks up up the dominant frequency from the sound board which is different for each guitar. And, until now, there was no way to notch that frequency out of the K&K (or any sound board transducer) without adding active electronics. Active electronics have a tendency to degrade acoustic tone.

James, quite cleverly, added two discs to a K&K design. The fourth disc doubles the high e string because K&K is usually weak on the high frequencies and the balance of the e string, specifically. The 5 disc is a large disc that is phase reversed to cancel out a desired frequency that the other 4 discs sense. The passive circuit board does the phase cancelling based on a frequency that you set with dip switches. You set the dip switches based on testing using an exciter, amplifier and a sine wave generator. Once you're done, the pickup can always notch out the largest feedback causing frequency. You get the benefit of higher gain before feedback, less mud in your tone, and more high end presence.

What's not to like? Well... the installation. That's a challenge that I'll be curious to see James overcome in the coming months.

James May · #8 03-01-2018, 12:48 PM

Thanks to Aaron for a very nice demo!

A few questions have been raised about how the Ultra Tonic pickup works, and how it's different than the K&K.

EVERYTHING SHOULD BE MADE AS SIMPLE AS POSSIBLE, BUT NOT SIMPLER—ALBERT EINSTEIN seems an appropriate way to begin the explanation.

The Ultra Tonic pickup consists of three components:

1) Four piezo discs (12mm) that get glued to the underside to the soundboard bridge plate, right below the saddle area. K&K uses three similar discs. In my experience K&K almost always ends up with a weak high E string, so I added a 4th disc to fix that problem.

Together this set of discs pick up the desired string response, with great string-to-string balance and a very natural sound, especially the attack and lack of quack. But they also pick up a fair bit of undesirable top plate resonance. This results in low end muddiness, and too much feedback susceptibility. Remember it is the top plate's main resonances that are going to start feeding back first. The two main ones are typically low G# and then the F above.

2) A fifth piezo disc (20mm), out of phase with opposite polarity, that gets glued to the far bass corner of the bridge plate.

This component picks up lots of the undesirable top plate resonance, and only a little bit of the desirable string response.

3) A passive balancing circuit board mounted to the endpin jack. It contains a 12 position dip switch that functions as a balance control which determines how much of the out-of-phase disc gets mixed in with the main discs.

Here is the part that is unusual (and I should mention patent pending), and seems complicated (at least at first): If the discs are blended together in a proportion such that the resonance level is about equal in strength, because they are opposite in polarity they will cancel each other out, leaving only the desirable string information.

In order to most accurately find the correct setting for the dip switch, you need to cause the top plate to resonate at one of the main resonance points, then try each of the 12 switch positions to find the one that gives the lowest output of the resonance. It will not change the output level of the desirable string signal.

You could do this by ear, but a more sure fire approach is to use a signal generator set to resonance, driving the calibration exciter sitting on top the guitar. The exciter is like a speaker without a cone, and turns the guitar top into a speaker.

Then it's a simple 5 minute procedure to find the best dip switch position. Once you've got it, your done.

martingitdave · #9 03-01-2018, 01:05 PM

Thanks James. Since I am doing the install sometime today or tomorrow, have you documented the mapping of the frequencies to the dip switch? Those of us who happen to know which open string or fretted note feeds back already might be able to just go directly to the right dip switch. Just trying to think of ways to simply.

James May · #10 03-01-2018, 01:18 PM

Quote:

Originally Posted by martingitdave

Thanks James. Since I am doing the install sometime today or tomorrow, have you documented the mapping of the frequencies to the dip switch? Those of us who happen to know which open string or fretted note feeds back already might be able to just go directly to the right dip switch. Just trying to think of ways to simply.

The dip switch does not map frequencies. Think of it as a balance control that is frequency independent. When it is set correctly, it causes the out of phase element to be mixed in with just the right strength such that the offending frequencies will be greatly attenuated, whatever they happen to be on your instrument.

Summarizing a different way: It is the balance proportion that you are finding with the dip switch setting, which is particular to each installation, rather than notching frequencies.

martingitdave · #11 03-01-2018, 01:48 PM

Quote:

Originally Posted by James May

The dip switch does not map frequencies. Think of it as a balance control that is frequency independent. When it is set correctly, it causes the out of phase element to be mixed in with just the right strength such that the offending frequencies will be greatly attenuated, whatever they happen to be on your instrument.

Summarizing a different way: It is the balance proportion that you are finding with the dip switch setting, which is particular to each installation, rather than notching frequencies.

Ah, that is very interesting. Thanks for explaining. That prompts a number of additional questions that I will hold for the time being. Though, I have a better sense of what the circuit design is doing. Thanks!

guitaniac · #12 03-01-2018, 04:11 PM

Quote:

Originally Posted by James May

The dip switch does not map frequencies. Think of it as a balance control that is frequency independent. When it is set correctly, it causes the out of phase element to be mixed in with just the right strength such that the offending frequencies will be greatly attenuated, whatever they happen to be on your instrument.

Summarizing a different way: It is the balance proportion that you are finding with the dip switch setting, which is particular to each installation, rather than notching frequencies.

Given the dip switch is set correctly, will the out-of-phase sensor also reduce problems caused by the guitar top's interaction with the amplified frequencies coming from other instruments, like a bass, for instance.

I'm wondering if the ultra tonic will work as well (in terms of rejecting feedback and providing a clean tone) as a UST will work in a loud band setting.

Beagle1 · #13 03-01-2018, 06:43 PM

Thanks to Aaron for the very helpful demo video, and to James for explaining in detail how the Ultra Tonic pickup works.

This thread has given me a lot to think about and I'm very close to ditching the K&K Trinity system I've had in one of my Martins for years.

I thought the pickup even without the Tone Dexter processing sounded quite natural, especially with the EQ adjustments. If it can sound that good through a PA at decent volume, I'm sold!

James May · #14 03-01-2018, 07:17 PM

Quote:

Originally Posted by guitaniac

Given the dip switch is set correctly, will the out-of-phase sensor also reduce problems caused by the guitar top's interaction with the amplified frequencies coming from other instruments, like a bass, for instance.

I'm wondering if the ultra tonic will work as well (in terms of rejecting feedback and providing a clean tone) as a UST will work in a loud band setting.

Yes, and yes.

No matter what is causing the guitar to vibrate, be it a close by bass or it's natural resonances, the effect works the same.

I have found the feedback resistance of the UTP to essentially be equivalent to the common USTs like Fishman (AG, Matrix Infinity, Sonicore) and Baggs (Element) and Highlander. That is to say, you can play quite loud without issues. It is not quite as good as the USTs with out of phase elements like Barbera and RMC and LB6 which are designed for extreme conditions.

guitaniac · #15 03-02-2018, 06:35 AM

Quote:

Originally Posted by James May

Yes, and yes.

No matter what is causing the guitar to vibrate, be it a close by bass or it's natural resonances, the effect works the same.

I have found the feedback resistance of the UTP to essentially be equivalent to the common USTs like Fishman (AG, Matrix Infinity, Sonicore) and Baggs (Element) and Highlander. That is to say, you can play quite loud without issues. It is not quite as good as the USTs with out of phase elements like Barbera and RMC and LB6 which are designed for extreme conditions.

That's very encouraging. Thanks for the observations, James.