dove Posted July 12, 2012 Share Posted July 12, 2012 General consensus seems to be that most amps benefit from a preamp between db and amp primarily to match the impedance for a piezo type pickup.Some amps have a suitable input but even then a preamp may be used for a favoured sound. I'm thinking of buying a PJB flight case which my research shows is a reasonable choice but it will require a preamp.Ok so again after a bit of surfing the fishman platinum pro seems well thought of. I'm currently using an lr baggs dual input but to my ears it adds a fair bit of noise to the signal. Here's my dilemma.What's the point of buying an amp with a sweet eq,low noise floor,quality preamp etc only to stick another preamp before it? Is there not a impedence matching something or other that overcomes the level matching without adding anything else? Currently using a realist pickup but thinking of trying a full circle.I'm guessing that different piezos and transducers have different output levels,or do I mean impedance levels? Is it just the gain on the first preamp that matches thing up or is there an impedence issue as well? It's a jungle...and I'm a bit lost..... any pointers much appreciated Quote Link to comment Share on other sites More sharing options...
Mr. Foxen Posted July 13, 2012 Share Posted July 13, 2012 Impedance matching thing is called a buffer. The are kind of part of the preamp, you want a preamp with a high impedance, some have it, and some don't. A simple high impedance buffer circuit is pretty easy to knock up. Quote Link to comment Share on other sites More sharing options...
ikay Posted July 13, 2012 Share Posted July 13, 2012 TH Audio make a piezo buffer pedal, details here - http://www.thaudio.com/product_info.php?products_id=33 Loads of buffer circuits on the web so as Mr Foxen says it shouldn't be too hard to knock one of these up yourself. Quote Link to comment Share on other sites More sharing options...
TPJ Posted July 13, 2012 Share Posted July 13, 2012 [quote name='Mr. Foxen' timestamp='1342138462' post='1730415']A simple high impedance buffer circuit is pretty easy to knock up. [/quote] There is a chap called fdeck on Talkbass that has designed one, he is a double bass player. [url="http://personalpages.tds.net/~fdeck/bass/hpfpd.pdf"]It's this one.[/url] Quote Link to comment Share on other sites More sharing options...
bassace Posted July 13, 2012 Share Posted July 13, 2012 [quote name='TPJ' timestamp='1342166604' post='1730523'] There is a chap called fdeck on Talkbass that has designed one, he is a double bass player. [url="http://personalpages.tds.net/~fdeck/bass/hpfpd.pdf"]It's this one.[/url] [/quote] And it works. I have a later one with a vol control although I never use that. It has a phase shifter - great for addressing feedback, a great control for killing any boom and of course it buffers the impedance. It slots in nicely under the amp's carry handle. Trouble is Francis Deck hasn't got a licence to export so you can't get his gizmo over here. If you are serious about getting one I suggest you subscribe to TB and put out a post asking if anyone can ship you a 'second-hand' one. Just to complicate the whole preamp thing, I also have Fishman pro eq: sometimes this works better and sometimes the fdeck according to the room. Funny old world. Quote Link to comment Share on other sites More sharing options...
derrenleepoole Posted July 13, 2012 Share Posted July 13, 2012 I've always found PJB stuff to be very well matched for EUB's and piezo pickups even without a preamp - but that was just me. Of course, nit all PJB amps have an XLR in either. If you are going to use a preamp, it doesn't need to be too fancy. I had a simple Fishman B preamp that did the job very well without any real colouration to the tone. Had bass and treble on it, clipped to my belt and give a good signal to the amp to help get a good clean out through it. The EQ on the preamp was useful as I could dial in or take away basic tone without being over the amp during playing if required. Quote Link to comment Share on other sites More sharing options...
TheRev Posted July 13, 2012 Share Posted July 13, 2012 Whether you use a preamp and which one you use is laregly a matter of taste. Some pickups sound great straight into the input of amp X but horrible and nasal through amp Y. As it happens, last night I was faffing around with different combinations of pickups (K&K bassmax & Tacoman) preamps (Fishman Plat pro and Headway) inputs (standard input or via preamp into the FX return) and sawpping the pickups between the treble and bass bridge wings. Very long story short; the K&K mounted on the treble side sounded good straight into the main input without a preamp, as did the Tacoman when mounted on the bass side of the bridge. I have done gigs with my Realist equipped EUB going into the fromt of my LM2 when my pre input died - not a sound I'd choose to use, but not a disaster either. I theink experimentation is the key. When you get your pickup and amp, try it without a preamp and see if you like the sound. If you don't then a preamp will certainly improve things. As mentioned above, Francis Deck has a very simple impedance matching preamp that you can build yourself from his plans. Quote Link to comment Share on other sites More sharing options...
dove Posted July 13, 2012 Author Share Posted July 13, 2012 That's all really helpful,I'll try my lr bags mix pro first if the PJB even needs a preamp.I have a drawl of pickups to try! The buffer info also to be looked at.... thanks again Quote Link to comment Share on other sites More sharing options...
keeponehandloose Posted July 13, 2012 Share Posted July 13, 2012 Matching the impedence will cure tone issues such as nasaly thin sound,but then a gain stage is needed to boost the signal from the piezo to a level that an amp can work with. Hence a pre amp is recomended for piezo pickups. Quote Link to comment Share on other sites More sharing options...
Bass Wielder Posted July 14, 2012 Share Posted July 14, 2012 I've beeen using John East's STMP 01,'Stomp box' as a pre-amp with my double basses and I've had great results. It was not designed for this use (I guess) but...as long as it works. I usually use this as my D.I. with electric basses anyway so it was a good investment. I also use his MPB 01 'piezo -pre', blending my Realist and Underwood. Brilliant combination (Stomp and this) and I've had positive comments of my 'acoustic' sound. Whatever your choice of pickups use your ears!! My advice..talk to John. Right in our back-yard with some world class stuff. I go to John, first, to solve or at least advise with my audio stuff and I must admit even with my double bass issues..... Quote Link to comment Share on other sites More sharing options...
bobmartin Posted July 14, 2012 Share Posted July 14, 2012 You won't need a pre-amp with a Suitcase or Briefcase, I've owned both, the input impedance is suitably high to match most DB pick-ups. Quote Link to comment Share on other sites More sharing options...
artisan Posted July 19, 2012 Share Posted July 19, 2012 i tried a plat' pro & didn't like it at all so now i just use a Boss bass eq pedal which also matches the imput impedance too. Quote Link to comment Share on other sites More sharing options...
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