000-18GE + K&K Pure Mini Disaster: solved?

SongwriterFan · #1 04-23-2021, 02:22 PM

I've been doing Open Mics now for over three months, and the guitar I chose to play with is my Martin 000-18 Golden Era that has a K&K Pure Mini installed in it. It seems to work very well with my voice, and has the benefit of being a "low maintenance" guitar (no battery, and seemed to always work well at gigs).

Well, that last part changed in the last few weeks. And this was at a venue that I've been at multiple times, where the setup always seemed to work. But two weeks ago, the guitar sounded "tinny" to me (and others noticed, too). OK, the sound is typically run by the owner, who also is up on stage playing a lot of the time, so I didn't worry about it too much. But this week, the guitar sounded HORRIBLE during the sound check (I get there early).

No matter what he did to the sound (I let him deal with it, it's his place and his equipment, and while I know my way around a sound board, I figure it's best not to try to get involved unless asked). Did I say it sounded horrible? Lots of feedback, and the guitar sounded more like an electric piano from the 70's than a guitar. Kind of a cool effect, if that was what I was going for . . but I wasn't.

I ended up using his guitar (also a Martin, and I believe a Baggs Element pickup). It sounded a lot better than mine.

I feel obliged to state AGAIN that this same guitar and pickup worked fine all the previous times I played there (probably 6 - 8 times). I doubt anything changed in my guitar (I did change strings, but I'm pretty sure they're the same ones I was using before). I even went by the guitar store today and had the tech look at the K&K install to see if he could see anything wrong, and he couldn't see anything obvious.

I should also point out that I had been recording with this guitar at home just hours before going to the Open Mic, and it seemed fine. I was going through a Baggs Venue DI, but all the EQ was set at noon.

Today I went by the guitar store, and played into one of their acoustic amps. I think an AER. It definitely sounded "bright" and a bit "tinny", but nothing like what I heard a the venue.

I tried a Baggs Session DI (I have the box without DI on my pedalboard), and that didn't improve the sound all that much. We also tried a Baggs PADI DI, and the improvement came when I dialed by the sweepable mids all the way, with the frequency set to 1.6 kHz.

They didn't have an unopened Venue to try, so I went home to get my pedalboard with the Venue on it, and I also grabbed my K&K Pure pre-amp. I was going to try the Venue, but didn't have to because the K&K pre-amp seemed to solve the issue. I didn't want to mess with taking the Venue off my pedalboard if I didn't have to.

The solution using the K&K Pure Pre-amp was to dial back the Mids all the way (I think it's -20db, and is an "extra large bandwidth" centered at 1.5 kHz according to their website. Which fits well with the 1.6 kHz I had tried on the PADI.

So, this seems to solve the problem. I like that the K&K pre-amp is small, easy to use, and runs off a single battery (which should last 180 hrs). At these Open Mics, I've always been handed a 1/4-cable. So I can just plug the output of the pre-amp into that cable. And I plan on using my wireless connection from the output of the guitar to the input of the pre-amp, just to avoid having to carry an extra cable or ask for one.

So, I think this solves my problem.

Anything else I should consider? If I were doing my own gig or opening for somebody, I would try to use my Bose L1 Compact and use my pedalboard, which has everything I want/need to control my vocals, guitar, and mixing before going to the amp.

jonfields45 · #2 04-23-2021, 02:48 PM

The open mic probably plugged you into a 10K ohm line input that night, which works fine with any active guitar, but is much too low for a passive piezo SBT.

Into too low a load impedance and a passive piezo becomes a high pass filter where you lose much of the lows. Any simple buffer (1M ohm input impedance is ideal, but >200K will likely be just fine too) will solve that problem.

However, once you spiral into the infinite perfecting of equalization, you are probably better off with an IR such as ToneDexter.

SongwriterFan · #3 04-23-2021, 03:01 PM

Quote:

Originally Posted by jonfields45

The open mic probably plugged you into a 10K ohm line input that night, which works fine with any active guitar, but is much too low for a passive piezo SBT.

It's the same "snake" as always. But their DIs (either passive, or phantom power, I don't know which), have dual 1/4" inputs. Would they both be the same impedance, or would one be high and one low?

I also learned today that some of the tone I was hearing was probably because they needed to invert the phase on the guitar channel.

Quote:

However, once you spiral into the infinite perfecting of equalization, you are probably better off with an IR such as ToneDexter.

I've got a ToneDexter, and I've played around with it some (though not on this guitar). But it won't run off batteries, so it's just one more thing for me to have to lug around and worry about. It seems to be overkill for an Open Mic.

I've thought about trying the new VoicePrint DI from Baggs, too. But it also won't run on batteries. From a "techno-geek" (which I am) point of view, it should be fun. I just don't think it'll work well for the Open Mic situations I find myself in now.

jonfields45 · #4 04-23-2021, 03:14 PM

Phase inversion will not dramatically change the tone in my experience but can be very useful for controlling low frequency feedback. It is possible the DI that night did not provide a high enough impedance.

You can run ToneDexter off off one of these:

https://www.amazon.com/current-Negat.../dp/B07GD54Q66

And any handy USB battery. Here's a couple of cheaper ones I own and like:

https://www.amazon.com/TalentCell-Re...1M7Z9Z1N&psc=1

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

SongwriterFan · #5 04-23-2021, 03:28 PM

Thanks . . . I've got a USB battery that should work.

Have you ever looked at the Ultratonic upgrade to the K&K by James May Engineering?

http://jamesmayengineering.com/how-it-works/

SongwriterFan · #6 04-23-2021, 03:31 PM

The other solution for powering the ToneDexter might be a rechargeable pedalboard, like this one. I have its larger brother (the pedalboard I referred to earlier). I would have to see how well it fit onto this smaller board.

https://www.theguitarsanctuary.com/O...rd-p/17346.htm

martingitdave · #7 04-23-2021, 03:37 PM

The others are correct. All my guitars have K&K pure mini. They work great into most acoustic amplification. Occasionally you get a weird system and need the external preamp. No biggie. Tonedexter is the primo if you are interested.

phcorrigan · #8 04-23-2021, 04:45 PM

Quote:

Originally Posted by jonfields45

https://www.amazon.com/TalentCell-Re...1M7Z9Z1N&psc=1

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

That's what I do. Works great!

sdelsolray · #9 04-23-2021, 07:09 PM

Years ago had a K&K SBT pickup go wacky with behavior and sound very similar to what you describe. It turned out that one of the sensors had become loose. Dunno how but it did. Glued it back in place and it worked fine.

SongwriterFan · #10 04-24-2021, 11:02 AM

Quote:

Originally Posted by sdelsolray

Years ago had a K&K SBT pickup go wacky with behavior and sound very similar to what you describe. It turned out that one of the sensors had become loose. Dunno how but it did. Glued it back in place and it worked fine.

That was exactly what I thought the problem would turn out to be. But as I mentioned, the tech didn't see anything wrong with it.

I assume your issue was SUPER-obvious once you looked at the inside of the guitar? I still kinda wonder if something less obvious has changed on mine.

SongwriterFan · #11 04-24-2021, 11:04 AM

Quote:

Originally Posted by martingitdave

The others are correct. All my guitars have K&K pure mini. They work great into most acoustic amplification. Occasionally you get a weird system and need the external preamp. No biggie.

It still baffles me, though, why I didn't have issues at the venue previously. As far as I can tell, nothing changed. I suppose they could've had a big cut in the mids dialed in before (unknowingly) and somehow that got taken out in the last two weeks, and they could've solved the issue by just dialing in the right EQ.

I did confirm last night, though (went there to listen to a performance) that the DI inputs are 50 kohm. But I'm very sure (but not certain) that those were the same DIs that I had used before, when the issue wasn't apparent.

tadol · #12 04-24-2021, 12:15 PM

I’d double check the connections on the K&K - no idea how, but a partially failed glue joint, or a poor connection at the jack, could be a culprit, and those problems can be a real pain until discovered -

The UltraTonic upgrade is well worth the cost and effort to install and tweak - it will give you a much nicer signal, and eliminate any feedback potential, plus a volume wheel that doesn’t mess with the EQ -

SongwriterFan · #13 04-24-2021, 12:21 PM

Quote:

Originally Posted by tadol

I’d double check the connections on the K&K - no idea how, but a partially failed glue joint, or a poor connection at the jack, could be a culprit, and those problems can be a real pain until discovered -

The UltraTonic upgrade is well worth the cost and effort to install and tweak - it will give you a much nicer signal, and eliminate any feedback potential, plus a volume wheel that doesn’t mess with the EQ -

That's kinda what I'm thinking. There is a place in town that carries K&K, but not sure if they're familiar with the UltraTonic.

I also wonder how possible it is that the K&K has an issue that can't easily be solved.

I'm wondering if it would be better just to get the full UltraTonic, instead, just in case? Any idea how much better (or worse?) that is than using the K&K with the upgrade?

tadol · #14 04-24-2021, 01:06 PM

I’ve done both - the upgrade kit works great, and isn’t really difficult to install. You just take the leads from the 3 K&K transducers and solder them down to the tabs on the UT board, and glue in the extra transducers on the bridge plate. The volume wheel is optional, but it’s just a self-stick to the inside of the soundhole, and works great.

If you wanted to do the whole new UT install, you’d have the old K&K transducers to remove first, which might be a pain. The main advantage to a new install is that James designed the main UT transducers so they all go in as one single unit, so thats much easier, both to glue in and to align with the saddle. Otherwise, there isn’t really any difference.

The challenge/fun part is working with the switches on the custom circuit board to cut the feedback potential and get the best tone. Just takes some time, and making some choices. When you have it, then slip the jack into the guitar and button it up -

If the UT upgrade is something you’re really considering, get in touch with James and maybe he can help with diagnosing your issue, as he is a real expert in all this, and won’t sell you more than he thinks you’ll need.

jonfields45 · #15 04-25-2021, 07:13 AM

Quote:

Originally Posted by SongwriterFan

I did confirm last night, though (went there to listen to a performance) that the DI inputs are 50 kohm. But I'm very sure (but not certain) that those were the same DIs that I had used before, when the issue wasn't apparent.

50K ohms is not going to sound good with a passive K&K. It will act as a low cut. But just because it is spec'd at 50K, doesn't mean that some input on some sample of that DI is not a bit higher. Just 200K would do the trick.