K&k impedance question

[7thbassbA]

So I hear the output impedance is 1M ohm. I have a soul food pedal with similar input impedance. If I put that pedal between guitar and other stuff would that address the problem (of it is a problem) of impedance mismatch?

[jonfields45]

I don't know the output impedance of a K&K, but it is recommended by the manufacturer, and well verified on the AGF, that you can't go wrong with a 1M load. At some point in the last few years, Doug Young posted his results using a variably input impedance buffer on a K&K and 1M is solidly in the good.

If you plug the K&K into a mixer line input, typically 10K ohms, or worse yet a mic input at typically 3K ohms, you will hear the series capacitance of the piezo cut off the lows rather extremely.

[sdelsolray]

Originally Posted by 7thbassbA

So I hear the output impedance is 1M ohm. I have a soul food pedal with similar input impedance. If I put that pedal between guitar and other stuff would that address the problem (of it is a problem) of impedance mismatch?

The output impedance of a K&K mini pickup is not 1 MegOhm, but is much lower and varies depending on frequency. The 1 MegOhm spec is a recommended value for the input impedance of the first gain stage/buffer to which the K&K mini pickup is connected.

When connecting a K&K to that first gain stage/buffer the correct term as to the connection is impedance bridging (not impedance matching).

The 1 MegOhm input impedance of your soul food pedal is just fine. What that pedal connects to next in your signal chain may be fine or not so fine depending on the output impedance and output gain of the pedal and the input impedance and acceptable input gain range of the next device in that signal chain.

[Ed-in-Ohio]

Originally Posted by 7thbassbA

So I hear the output impedance is 1M ohm. I have a soul food pedal with similar input impedance. If I put that pedal between guitar and other stuff would that address the problem (of it is a problem) of impedance mismatch?

I have been using my Soul Food set to clean boost (gain set to minimum) as a preamp with the K&K and I am loving the results! I have owned several of the highly recommended acoustic preamps, and the Soul Food performs as well as all of them, and better than most.

Love how the treble control on the Soul Food allows for tone balancing.

To your direct question: The input and output impedances of the Soul Food are very K&K and signal chain friendly. The input impedance is 1MOhm & the output impedance ranges from 650Ohm to 3.3kOhm.

I plan on adding a passive DI after the Soul Food and making it my regular acoustic preamp.

Great, quiet pedal with tons of headroom.

[SalFromChatham]

I placed a Boss TU3-W pedal between my k&k and Bose. Same idea.

[7thbassbA]

Thanks everyone. Very helpful.

[lkingston]

An active directbox is inexpensive and made for exactly this situation: plugging passive instruments into a mixer. I use this one. Like many, it can either be powered by phantom power from the board or a 9v battery:

https://www.sweetwater.com/store/det...ent-direct-box

[ljguitar]

Originally Posted by 7thbassbA

So I hear the output impedance is 1M ohm. I have a soul food pedal with similar input impedance. If I put that pedal between guitar and other stuff would that address the problem (of it is a problem) of impedance mismatch?

Hi 7th-b etc

It's an alleged mismatch. What's alleged is that it's some huge issue...it's not.

With most PA systems and preamps and PA boards (or acoustic amps), the K&K sounds fine as is. If there is any side-effect it's a bit too much bass so you might have to turn the low EQ down a touch.

There is a lot of discussion here on the forum about this if you do a little digging in the archives. There are even hi-rez recordings out there.

Hope you find the answers you need.

[lkingston]

I hear this issue every week at an open mic I attend. There is one guy who has a Martin guitar with a factory installed passive pickup. It’s happening again tonight, so I will bring my active Samson directbox just for him. Without the directbox the sound is overly bright with no lows or low mids. With the directbox it sounds like a Martin guitar. I tried a passive directbox last week and it was ok, but not as good as the active.

Yes, you can use an expensive high end preamp, but if your goal is to make a passive system sound as good as a battery powered system, the active directbox is all you need.

[000M]

I have a K&K Pure Mini in my Martin and my experiments have led me to these conclusions:

1. Plugging it into the 'wrong' input impedance won't break anything. It will still make a guitarry acousticcy sound of some sort. The difference is that plugging into a 1 M ohm buffer/line driver/active DI increases your chances of enjoying the sound.

2. Not all 1 M ohm buffers/line drivers/active DI's are created equal. Just because a thing has a 1M input buffer doesn't mean that I'll like the sound it makes. I own several buffered things (mostly pedals) that have 1 Meg inputs ...and I'm still not 100% happy with any of them. I highly recommend trying out a bunch of different active devices to find your perfect solution.

I have tried these 1M buffered bypass beasties (among other things):
- Crowther Audio Hot Cake
- Boss LS-2
- DOD Bifet Boost 410
- MXR M87 Bass Compressor (same circuit as MXR M76)

The M87 (effect-on but set to high threshold) has the best bottom end but is slightly scooped and a little aggressive in the hi mids.

The Bifet Boost has the sweetest mids and a nice sheen in the highs but the lows doesn't seemed to go as low, possibly due to the tone control.

I was surprised that I didn't like the Hot Cake buffer with the K&K, especially given how much better it makes my electric sound just being on my pedalboard.

Didn't like the LS-2 buffer either. To me it was kinda hashy in the highs and overall too coloured in a negative way. I know I'm not the first to have an opinion on a Boss buffer...

I've also got a Diamond Comp winging its way to me. I've heard good things. Can't wait to try it! I'll report back.

[varmonter]

I have a diamond comp in my signal chain.
It's a nice quiet pedal. it's on all the time but
not dialed to squishy if you know what i mean.
My pre has 3 input impedance settings .
i usually leave it set on 1mgohm.
I think if you have a kk you live with these
issues. They sound great but require outboard
gear to get them there.
I've tried a 5gal bucket full of devices over
the years. Some work some don't . It doesn't seem to
matter how much they cost. 150 for a kk pure xlr and i would never
sell that little box. I paid a grand for a pendulum and sold
it weeks later. Just didnt work. I use a Felix now along with
the comp and a couple of effects pedals.

[lkingston]

The input impedance on the Samson MDA1 active directbox is 1MΩ. The output impedance is 200Ω. As compared to a passive directbox, there is about 30db more gain. Sound is very good. The case is rugged metal. It is powered by phantom power if you have it, a battery if you don’t. It works very well with passive pickups (that’s the whole point of active directboxes) and is just $35.

[Br1ck]

Originally Posted by lkingston

I hear this issue every week at an open mic I attend. There is one guy who has a Martin guitar with a factory installed passive pickup. It’s happening again tonight, so I will bring my active Samson directbox just for him. Without the directbox the sound is overly bright with no lows or low mids. With the directbox it sounds like a Martin guitar. I tried a passive directbox last week and it was ok, but not as good as the active.

Yes, you can use an expensive high end preamp, but if your goal is to make a passive system sound as good as a battery powered system, the active directbox is all you need.

This is what I heard every week at the open mic I attend. People either buy a guitar with a piezo, or have one installed, then show up at an open mic and plug direct to a board. I got so tired of hearing $4K guitars with K&K pickups sound thin and harsh that I had a DI built just for open mic so I didn't have to hear it anymore. Thank you SunnAudio.

[ljguitar]

Originally Posted by Br1ck

…I had a DI built just for open mic so I didn't have to hear it anymore. Thank you SunnAudio.

Hi Br1ck

For whatever reason, it was nice of you to do that.