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View Full Version : passive pickups need preamp?



UkerDanno
01-15-2016, 04:27 AM
I have an early Pono with a factory installed Dean Markley Under-saddle Passive Pickup, according to this info:
http://web.archive.org/web/20060315101917/http://www.koolauukulele.com/pono.html
thanks to Rakelele for finding this info.

Anyway, I know nothing about pickups and/or amps. Last night at a club meeting, I tried it on the club amp and it worked, but the leader, who is a very experienced professional performer, said I needed a preamp.

I mean, it worked, I don't know how far he had it turned up or anything, as I said, I know nothing about amps and such.

Can someone clue me in a little bit?

Mahalo :shaka:

Jon Moody
01-15-2016, 04:42 AM
Do you need a preamp with a piezo pickup? Technically, no.

However, it will help you immensely in terms regulating your input level, overall volume and tone.

DaveY
01-15-2016, 04:44 AM
My experience is that my passive-pickup ukuleles sometimes need a preamp through a PA, but usually not through an amp. (Mine all have a Pono passive.) One solution is to buy a clip-on external pre-amp that you can have if you need it. I like the K&K Pure Preamp. You also could get a short cable to connect the preamp to the instrument. Baggs makes a clip-on, too, but I didn't like the battery environment (if that makes sense). There are more expensive (and better) preamps, such as the Baggs Para DI, but I think the K&K ($99 these days) would do the job and be less intrusive, especially when using someone else's PA/amp rather than your own.

UkerDanno
01-15-2016, 05:09 AM
Markley has this:
http://www.stringsandbeyond.com/dema31goriac.html
looks like it's installed inside the uke?

I just don't want to have a lot of equipment! Was thinking of that Kustom PA50 amp discussed in another thread...guess maybe I could go down to Guitar Center and try one out.

Jon Moody
01-15-2016, 05:15 AM
Markley has this:
http://www.stringsandbeyond.com/dema31goriac.html
looks like it's installed inside the uke?

I just don't want to have a lot of equipment! Was thinking of that Kustom PA50 amp discussed in another thread...guess maybe I could go down to Guitar Center and try one out.

You'd have to confirm with Pono that they installed that in your uke, in addition to the piezo.

And yes, it takes the place of the endpin jack and saves you needing a preamp (although it doesn't give you any actual controls, from the look of it).

There are many acoustic amps (as in, amps designed for acoustic instruments, not the brand name) that have input channels designed to be used with piezos without needing a preamp. That is another option, while keeping the amount of equipment to a reasonable level.

Rllink
01-15-2016, 05:18 AM
When I was thinking about pickups, I was told that you could amplify the sound with a passive pickup, without a pre-amp, but not as well as you could with a pre-amp. I think that just making a louder noise is not the objective of amplifying your ukulele. I think that there is more to it.

UkerDanno
01-15-2016, 05:33 AM
You'd have to confirm with Pono that they installed that in your uke, in addition to the piezo.

I didn't mean I thought it was in my uke, just how it's used....

Jon Moody
01-15-2016, 05:42 AM
I didn't mean I thought it was in my uke, just how it's used....

Ah, got it. It WOULD be awesome if it was already installed.

Brad Bordessa
01-15-2016, 07:48 AM
I had a passive pickup long ago and it totally sucked without a preamp. With a preamp it was sort of useable. The difference in quality and usability between that first K&K (one-spot, I think) and the active MISI I upgraded to eventually was night and day - even with the preamp on the passive.

You could spend $150-300 on a preamp or you could put that money towards a better active pickup and having it installed. I highly recommend the LR Baggs Five-0. For $200 installed (on the high side, probably) you could have a pickup that sounds pretty darn good no matter what you plug it directly into. All that would be different is you'd have a little watch battery to change every so often. Beats the crap out of carrying a preamp around because you HAVE to. You could also get a MISI which plugs into the wall to charge, but I give the sonic edge to the Baggs.

hoosierhiver
01-15-2016, 07:58 AM
The Stagebug SB-4 Piezo DI is a great option.

kohanmike
01-15-2016, 01:53 PM
If it didn't have one, I've installed preamps with tuners in all my ukes and basses. I don't like to go to the amp for volume and tone, and I really don't like headstock tuners all that much. I get the preamp kits direct from China for under $30, which in most cases are the same ones that are in commercial ukes.

http://www.kohanmike.com/uploads/preamp.jpghttp://www.kohanmike.com/uploads/Isys+ preamp.jpg
http://www.kohanmike.com/uploads/Joyo JE-53.jpg

UkerDanno
01-15-2016, 02:04 PM
All this makes me wonder...what use is a passive pickup? A sales point?

Jim Hanks
01-15-2016, 02:10 PM
All this makes me wonder...what use is a passive pickup? A sales point?

Well it can be a "price point" issue certainly. Its less complicated so less expensive (generally). You could also view the lack of active circuitry an advantage in that it allows you to use the preamp you want (or none) instead of being "stuck" with the one in the uke.

Brad Bordessa
01-15-2016, 02:11 PM
Lighter. Often a passive uses the soundboard transducer style pickup which, when done right can sound more natural. Less moving parts.

Jim Hanks
01-15-2016, 02:14 PM
I seem to recall a ~$50 preamp box that got pretty good reviews with uke. Someone will probably know it before I can find it

Edit: here it is. http://forum.ukuleleunderground.com/showthread.php?74603-Behringer-ADI21-active-DI-preamp&highlight=adi21

photoshooter
01-15-2016, 04:27 PM
I just don't want to have a lot of equipment! Was thinking of that Kustom PA50 amp discussed in another thread...guess maybe I could go down to Guitar Center and try one out.




I seem to recall a ~$50 preamp box that got pretty good reviews with uke. Someone will probably know it before I can find it
Edit: here it is. http://forum.ukuleleunderground.com/showthread.php?74603-Behringer-ADI21-active-DI-preamp&highlight=adi21

Preface: I'm not a professional musician. I'm not even an amateur musician. Hell, I don't know if I'm a musician at all!

Sorry, got sidetracked...

I have MiSi pickups in 2 ukes and an Artec passive pickup in another. The Artec was $6 or $7.
I run them through the ADI21 referenced above and into a Kustom PA50. All three ukes sound great to my unrefined ears. If you're set on the PA50 I think the Behringer preamp is a good match. It will allow you to play for a low cost of admission and if you decide to upgrade later you'll probably have a better idea of what you need. (And with the money you save you can buy another uke) ;)

UkerDanno
01-15-2016, 05:24 PM
Thanks everybody for all the great information, I feel uh, enlightened, yeah, that's it! :shaka:

Booli
01-15-2016, 07:41 PM
Hi UkerDanno,

The most important technical issue that has not been mentioned yet is that the problem of going with just a passive pickup is one of impedance mismatch between the output of the passive piezo and whatever you are plugging in to, either an amp or PA mixer.

As mentioned by others, there are 'acoustic' amps, that are designed to take a passive piezo as input, and that is why they sound much better than amps designed for an electric guitar. The Fishman Loudbox Mini is just but one example, and other is the Kustom Sienna series, which come sin 15, 30 and 60 watt versions and is about half the price of the Fishman even with the 60 watt version.

I've discussed this exact problem in in great detail in nearly 5-6 threads over the past year. I suggest you use the forum search function, and search for the word 'impedance' (without the quotes) and read ALL of those threads. I go into more detail and provide links for further reading if you are so inclined. I will give a short summary here for now to tide you over.

Fellow UU brother ricdoug used to also talk about these issues, but I've not seen him on the forum in at least 6 months or so.

Most piezo pickups have an output of 1M (1 million) ohm impedance, and most guitar amps expect a 1k (1 thousand) ohm impedance at their input, and most mic inputs on a PA mixer expect to have a 250-600 ohm impedance at their input.

Most guitar and bass pickups have an output impedance of ~10k (10 thousand) ohms, and not much, if any problems occur going into a device that is expecting 1k ohms at the input.

The impedance mismatch with nearly infinite capacitance of the piezo means that you are basically getting a free high-pass filter in that mostly all bass frequencies below about 200hz are LOST at the input when you plug in a passive piezo without SOME kind of preamp. This is typically described as the dreaded piezo 'quack'.

Most preamps, whether internal or external expect the very high impedance of such a piezo and in fact will not only amplify the signal but also 'buffer' it, which converts the high impedance to a low impedance, and by doing so, you do NOT lose the low frequencies of the signal at the input of the amp or PA mixer.

Basically ANY proper preamp can do this by default.

If you are handy with a soldering iron, there are many free plans online that use about $10 worth of parts and you can build a simple source-follower JFET transistor circuit in about 15 mins if you can read a schematic diagram. You can also get a bit more fancy with another $5-7 worth of parts and add an op-amp to increase the gain from the first circuit, all running off a 9-volt battery.

Otherwise, as mentioned by others above, the Behringer ADI-21 ($29) is a stompbox type guitar-pedal preamp that is ALSO a DI box that gives you a balanced XLR output to run to the PA system as well as a parallel unbalanced out to go to an amp on stage that you can use as a personal monitor, and this keeps your signal hot while reducing the possibility of EMI/RF interference over longer cable runs. If you use a standard guitar cable (which is never balanced) longer than 15-20 ft, an unbalanced guitar cable acts like an antenna and can pickup stray radio waves and 60 cycle hum from nearby A/C power (both of which are part of the EMI/RFI that you do NOT want in your signal path and and sound).

Otherwise if you already have access to a DI box, you can also get a belt-pack style preamp and a 1-2 ft cable and move the preamp to other instruments if you have them. LR Baggs has a model called the 'Gig Pro' ($69) and Schatten has model called the Mini-Pre ($49).

Unless you are going to gig regularly and/or getting paid for it the LR Baggs Para DI preamp and similar that start @ $169 is likely overkill, but if you want to skip the upgrade path, then go right to the Holy Grail with the LR Baggs Para DI, that's what lots of the pros use.

Also there is a company called Radial that has a box that is a combo piezo buffer and DI box called the Tonebone PZ-DI, which I think is around $229 or so. This is the same company that makes the less expensive SB-4 ($79) that hoosierhiver mentioned above, but the PZ-DI has a few audio controls to help get the best sound.

It's late now, otherwise would I find the other threads for you and link them here, as they have deeper explanations and links for further reading if you want to know more about any of these things that I've mentioned.

If you have any questions about what I've said here, please do not be shy, and ask away, and I will do my best to help.

-Booli

UkerDanno
01-16-2016, 04:16 AM
Mahalo, Booli! Those Siennas look really nice!

There's a Crate XT65-R for sale locally, for $80, looks like it has a preamp?

Booli
01-16-2016, 04:42 AM
Mahalo, Booli! Those Siennas look really nice!

There's a Crate XT65-R for sale locally, for $80, looks like it has a preamp?


I have the Sienna 30 and I'm happy with it, and I have other amps as well, both larger and smaller.

The Crate amp has an input impedance of 470kohms, which seems odd to me, and it is designed for electric guitar. While it will technically 'work' in the electrical sense, your likely going to be losing some bass frequencies unless you add a preamp between your uke and this amp. Keep in mind that a tenor uke outputs sound frequencies down to about 80hz, and most likely audio below 200hz from your instrument will not be heard and it will sound 'quacky' and while you can mitigate this a bit with eq, you cannot recreate what is simply not there at the input.

You can see the manual for the Crate amp here:

http://www.crateamps.com/pdf/manuals/XT65R.pdf

Before I buy ANYTHING, I always try to get hold of the PDF manual and verify it will serve my needs.

I got my Kustom Sienna 30 used from Guitar Center online for $50 + shipping. It was more beat up than the photos, but I did not buy it for looks so it was ok, but there was a problem with the reverb module, which I fixed myself in about an hours time, and has been working great ever since. I know Crate used to make robust amps, I have a 1980's model 165R 60 watt bass combo amp with a 15" speaker that's still going strong since I bought it new back then. OTOH, the Kustom is also built like a tank.

I've not felt the need to spend more for the Fishman Loudbox amps, but if I were performing professionally, I'd definitely give them a good look, as well as the Roland AC33.

On a budget, many folks are very happy with the Kustom PA50, but I'd still recommend a preamp for your uke to use that as well.

Many choices, but if you understand the electrical requirements of using a piezo, you can make a choice that will give you a much improved sound as opposed to living with an impedance mismatch and 'just making the best of it'.

:)

Booli
01-16-2016, 05:04 AM
Here is one very popular example of a minimal bare-bones DIY piezo buffer circuit you can build yourself, or by one pre-made from the author:

http://scotthelmke.com/Mint-box-buffer.html
http://scotthelmke.com/Mint-box-buffer.jpg

Here is the $58 Schatten Mini Pre:

http://www.amazon.com/gp/product/B006AVA3TQ

http://ecx.images-amazon.com/images/I/41oA1JnxQuL.jpg

Here is the $99 LR Baggs Gigpro:

http://www.amazon.com/gp/product/B001E95KEW
http://www.lrbaggs.com/sites/default/files/gigpro-acoustic-guitar-preamp-slide1.jpg

Here is the $29 Behringer ADI-21:

http://www.amazon.com/gp/product/B000KITQK2
http://ecx.images-amazon.com/images/I/919JRdOHdNL._SL1500_.jpg


And there are others, that cost more, as I mentioned in a previous post.

bazmaz
01-17-2016, 05:49 AM
Not necessarily but it helps in my experience.

I only use passives. But I do use an off board pre-amp - I am not a fan of any of the prebuilt onboard powered pickups (the sort that run on button batteries) for a simple reason - an off board pre-amp of a decent quality (I use an LR Baggs) with a passive strip gives me

a) more tone shaping options
b) a far more natural tone to my ears.

Now - into an amplifier with a good acoustic stage - perhaps I can go straight without the pre-amp - it will work. But for recording / going into a desk - a pre-amp is essential for me.

My Baggs is super cool as together with a line out I can give an engineer an balanced XLR output from the uke too.

(this is the pre-amp I use - http://www.gotaukulele.com/2015/03/lr-baggs-venue-di-pre-amp-review.html )