K & K V El Cheapo

[DarwinStrings]

I know some of you mob are using raw piezo disks and others have used K & K mini's. Has anyone done any comparisons? With a set of K & K's coming in at under $100 nowadays I am wondering if there is a huge difference. I have not used K & K but have used the El Cheapo version which ain't too bad.

From a bit of internets reading I get the impression that there is not much you can do to improve a piezo disk (they are a pretty simple device) so where is the improvement in K & K? That is assuming the K & K are in fact disks and not film.

Jim

[P Bill]

Jim,
I use film for my basses, fully shielded. Film works under pressure but with a bit of flex, they are under each bridge foot on an
inner tube bed. My preamp has a separate terminals for each hot lead and ground lead.

Coming up I'll be using disks ( a first for me ) on an invented, Goanna themed, Australian Federation cigar box Kala U Bass.
I plan on 3 disks, shielded, and wired in parallel. off board preamp.

3 or 4 piezos in parallel is about the max because the impedance is halved for each one. in series the impedance is doubled for each one and would be out of control for one output.

[Allen]

I didn't understand a word you said Bill.

.....hmmm, time to take a electronics course.

[P Bill]

Allen,
I only know enough to get by and be annoying.

Piezos are high impedance, " acoustic " amps are designed for this high impedance.

Magnetic pickups are low impedance and have their own amps

Shielded piezos are covered in copper foil, the hot connection is insulated with tape before the foil surrounds the disk or film.
Shielded wire is also used. I also ground my preamp to the shielded control cavity on my basses. Everything is nice and quiet that way.

Series piezos...the output of one becomes the input of the next. ex: hot wire to inner disk of the first, ground wire of the first to inner disk of the next and on it goes...one circuit

Parallel.. each piezo has it's own hot and ground wire. 3 piezos, 3 circuits joined at one terminal.

I think that's why my bass sounds so good...separate terminals for two circuits.

[P Bill]

One of the other reasons the basses sound good, my preamps were designed for my basses by John Ratajczyk of BJ Amplifiers. John designs, builds and repairs valve amps.

[jeffhigh]

I've done a few non Gen disc piezo installs but not in instruments that are comparable to ones I have used K and K's in. (selmeroid, baritone)
The K and Ks seem to just be discs under a thin plastic cover all wired together in parallel at the output jack. I don't know whether there is any shielding under the cover, would have to destroy one to find out.
Disc size varied a little between the various models, the pure western seems to be a 12mm disc under the cover
On the advice of Paul (Ozwood ) about degradation of the piezo over time, I have been putting a coat of epoxy over the back.

[DarwinStrings]

Thanks Bill and Jeff. I reckon I will just have to buy some K & K's and check it out. I have tried the disk's (15mm) straight up and also encased in 1.5mm of silicon (.75mm each side) from reading the net it looks like the silicon will drop the output a bit but will find out once I string this guitar up and plug it in. I did not shield as they don't seem to have much noise anyway and thought shielding might add a bit of weight. I do have some of that old school shielded cloth wire and will give that a go next time to see how much noise it knocks out.

Jim

[Kim]

Have not ever done this but wondering if perhaps a squirt of Plastidip may be the ideal solution for coating the back of the pizo disks?



Cheers

Kim

[Tod Gilding]

Are you guy's getting good results insulating with plastic and silicone ?

I have been using various density wood discs, not sure that is the answer though

may have to try the plastic/silicone

[Trevor Gore]

I normally use K&Ks but have used a couple of others and Dick Smith piezos. The K&Ks seem to have a lot higher output, which on responsive guitars adds too much bass if you have a high (>10M ohm) input impedance pre-amp. I can plug the K&Ks straight into the aux input of a hi-fi amp and still get a decent signal at ~10k ohm input impedance. So one trick to getting the sound balance right is to match the impedance correctly for the instrument you have. With the K&Ks you have plenty of signal, so that's generally not a problem.

Whilst the K&Ks have been the best solution for me so far, they still don't seem to do the highs quite right on my guitars; I'm talking the stuff above ~5kHz here. This might be something to do with lead capacitance (always short on my set-ups, so not much place to go). I never have trouble with noise. They're dead quiet. Whatever noise there is comes from the amp. I hadn't heard about the degradation of piezos over time. What's that about?

[P Bill]

The degradation of piezos is new to me as well. I'm guessing here but it seems easier to get a good sound from low frequencies than high with piezos. Most of my basses get played through ordinary bass amps. I've only used piezo on a guitar once and it was store bought.

[DarwinStrings]

No idea about degradation either, solders can degrade and your wires are soldered to the ceramic and the brass disks

I tried the wood insulation first Tod but then reasoned that you glue the buggers to wood anyway and you are just adding a little more wood.

You can buy them with that stuff already on them Kim but around the same K & K price anyway. Also that stuff apparently does not stick so well, you can jut peel it off so I used silicon which sticks like the proverbial (a little tricky but I just made a mold of sorts to get it accurate). I have read that the point to the silicon/wood/hot glue insulation is to just remove the harsher sounds a bit like the sliding along the strings noise (it also decreases output).

I don't need a amp but it seems everything you make now has to be able to plug into something.

The thing that got me wondering was when I read that you can't do much to a piezo so then wonder what the magic is in K & K

Jim

[jeffhigh]

I dunno Paul (Ozwood) just told me that the back of a piezo was vulnerable to the environment and best covered I think he had encountered this at work.
Hopefully he will join the thread.

[ozwood]

Hi Gents,

piezos do degrade ovet time , even just exposed to incidental envrimental humidity and contaminents, I suggested epoxy because pound for pound it offers the best protectionand is non dampening, you could also try a electronic conformal coating, available from jaycar, some silicones acetic cure(vinegar)and may have the oposite effect of protection, it is also difficult to get thin and is also dampening, the dialectric properties of epoxy are well known , as are most conformal coatings,not so much sealants, another possibility is a flowable dialectric silicone like Dow corning 3140, buy still holds a bit of mass and still a bit dampening , my humble thoughts on the matter .

cheers,

[ozwood]

Please excuse the Typo's I sent this from my phone and as I am over 40 I am shit at typing and seeing the small screen , Now that I am home and read it ," How embarrasment ".

[DarwinStrings]

Thanks Paul. Typo's aside I have just added "electronic conformal coating" to my list of words that I understand and also added electronic conformal coating to my shopping list.

Jim

[Trevor Gore]

Thanks for that, Paul. What sort of timescales are we talking here? Given that the K&Ks already have some plastic coating on the "up" side and the edges will be covered in CA gel, is there anything to be concerned about?

[ozwood]

Hi Trevor,

I think the K&K's will be Fine as is, I suspect the Coating on the K&K's is a Black epoxy anyway , The suggestion it came out of a conversation with Jeff and another mate who both use "raw" Piezo's to make there own Pick ups.

We uses Piezo's for varoius task in some of our equipment and noticed a gradual degradation, It takes a Fair while , and is not a failure out right , more a degradation over a long period and a Change in performance also possibly caused by a combination of dust and humidity creating a high impedance brigde across the two plates , all subtle stuff , but I suspect exactly the reason K&K coat theirs.

I do nothing to the K&K's , But the Raw ones I use in the odd stomp box I make , I coat with a drop of epoxy , particularly around where the wires connect onto the disc, by the by, I use a sheilded cable to connect to the disc, with the sheild earthed to the ground of the output jack and have had no issues with noise.

Cheers,

[Trevor Gore]

Thanks, Paul. Nice to know the K&Ks should be good.

Now you've got me interested in the stomp box!

I have a customer wants me to build him an acoustic stomp box, basically a low platform that he wants to stand on and stomp. Real simple in some respects, but he wants a bit of a Roll Royce version. Any insights? He's not interested in the usual approx. foot sized electronic ones.

[ozwood]

Hi Trevor,

I've tried a Few different way's , The best I have forund is some Piezo's mounted under the top platform , But on a Big one may be a bit harsh , you could also try a condenser mic or a combo of both !

I get my Piezo's here http://www.steminc.com/SAMPLES_INT.asp? ... EZO%20DISC


Cheers,

[Trevor Gore]

Thanks for the link, Paul. Those guys know how to charge for shipping!

[DarwinStrings]

G'day Paul, I had a look at the site you posted and was wondering which size you buy for guitars and if they are Stainless Steel. Do you know if the SS is better than brass for guitar application. Do you buy pre-wired or do those tricky little solders yourself? The site quotes some different Piezo materials like SM411 or SM412, any idea on differences?

Jim

More questions than answers

[ozwood]

Hi Jim,

For the price K&k charge ,Particularly at the momement http://stores.ebay.com/Musical-Supply-D ... =127029733 I could not be bothered making them, I only use raw ones for the odd stomp Box , having said that the DIY Piezo Pickups I have heard sounded a Little harsh for my ears , and I think that was related to the size , so I gues if I were going to make some for a Guitar I'd be trying something smaller , possibly around the 10mm mark and soldering my own sheilded cable on , something like this http://www.ebay.com/itm/2-Conductor-Shi ... 3f23ef58c0, that's about all I can add .

Cheers,

[DarwinStrings]

No worries and thanks again Paul, This guy here seems like he knows what he is up to Trevor for stomping.

Jim

[jeffhigh]

I actually met him last saturday night Jim
The stompers sound quite good on the clips
He has his own ideas on pickups and is quite dismissive of the K and K's, but I must ask about the mass of his pickup heads, they look like they would be quite heavy.