Fishman Blender Conversion

[baja12]

I'm using a Taylor 355 12 string with the Fishman blender preamp and eq that has a Prefix undersaddle pickup and a internal condenser mic. The transducer is fine, but the condenser mic has never worked for me, as it's really prone to feedback and picks up all kinds of guitar body and pick noise. I want to use a magnetic soundhole pickup like the LR Baggs and would like to delete the mic and wire the mag pickup to the blender so that I can blend between transducer and mag. My question is about the impedance of the mic, which I assume will be low impedance, and the high impedance of the mag pickup. Can I just wire the mag pickup directly to the input from the deleted mic, or do I need to add components to adapt for the differing impedance level?

[Aura]

Yes,almost all ac.guitar mics will feedback since they are often small back-electret "Omni" type hence these pick up sound equally from all sides;the the problem will only increase if you had any on-stage monitors facing the guitar!I too have had this problem for years..& only now I'm on the way to taming it, or am i?

A better solution could be a parametric EQ box with a variable "Notch" filter,which you can connect between the guitar & amp I don't think you'd be able to incorporate this into the "Fishman itself since these preamps often use SMD components & it would be a futile exercise to add additonal components on to the circuit board! as well..besides you'd lose the warranty too!

Severe feed back can also be due to mismatch between the guitar/amp impedences! One solution I found was to send the guitar through a line mixer or on line level using a direct box.

As for swapping from a mic to a mag pu..it won't work.since there will be a severe loading effect due to the impedence differencs as you've already guessed.These 2 are so different in impedence,inpout signal current/voltages.

In my humble opinion,changing to a mag pu would actually change the whole sound charcteristics of your Taylor..,,thus defeating the whole purpose of the whole exercise.Just try your guitar with a mag pu before you make ay drastic surgery on the guitar..& you'll find that the sounds are so different!

[Enzo]

You can't have feedback unless the output of the amp has a way to finds its way back to the input. Generally a speaker facing the mic. As Aura points out, stage monitors will make it worse. But monitors aside, you might look at your guitar placement with respect to any speakers. Moving the speakers a bit more forward, toward the audience, or yourself backwards, might be effective, and chacking that they are not angled towards you.

[Aura]

I couldn't agree more.Enzo is spot on about the main cause of feed back due to incorrect placement or positioning of main speakers.
However,this is an inherent problem with almost all (electret) condenser mics regardless of other factors,since they are quite sensitive to ambient noises,especially in enclosed spaces.The other reason is,I guess,when a s.e.cond.mic is directly fitted to the body of a guitar,it just amplifies even a "minute" sound vibration it gets back from any sound source until it becomes an uncontrolable feedback, often around 100-150Hz.(please correct me on this if i am wrong)

I also gather that on the Fishman Prefix,the mic is permanently glued? placed in one position hence rendering it impossible to adjust the string/mic distance/height or direction etc.I think it's a sad oversight on Fishman's part, severely limiting the potential of otherwise a good preamp. B.t.w these are also installed on Cort CJX 5 ac.guitars among others.

If I were you I'd take it to a guitar technician/luthier & find ways to make the mic adjustable.(mount it on a small gooseneck with adequate physical isolation of the "mic-capsule" from the body.This will definitely help.

I've experimented a lot with UST,Ceramic discs & small ele.cond.mics and in my experience nothing can beat or come even close to the natural sound of a mic on guitars. Even a cheapo elec.cond mic bought on the E-Bay sound excellent-o!The next closest would be Piezo discs since these too exhibit a very natural response to the vibration of the guitar.However these are prone to feedback as well.
What is so ironic is that these 2 actually cost less than $0.50c a piece.

I find that UST's have very limited low frequency range & almost impossible to totally eliminate the "quacky" nasal sound on them!

Hey,people never stopped using mics just because they feed-back;did they?
I believe there are ways & solutions to overcome this " feedback" by careful design,placement of components at every stage.

But a "Twin T notch filter" is actually very effective indeed in reducing/eliminating feedback!

[Aura]

You could also try using sound-hole cover;you know these round plastic lid like covers.I have infact watched one "TCGP by the name of Tommy Emmanuel himself using one on a MATON acoustic.Didn't hear a whistle the whole evening!He wasrumoured to be using an API system through a AER club 60 I gather

One other thing I suspect,is that the mic fitted on the Taylor could be actually a contact transducer. If this is the case I woulud ask the guitar tech to replace it with a a good ECM or atleast en Pansonic WM61A capsule which costs a mere $2-3 dollers a piece (Digikey still have them)
These are så cheap & versatile.you can afford to detroy as many as you like!

Good luck

[baja12]

Thanks aura and enzo for your thoughts, and I'll try a sound hole feedback cover. And I will try an electret mic mounted a goose-neck inside, and see if it works better than the condenser mic mounted on the preamp blender on the fishman. On the gooseneck, maybe it won't be so sensitive to guitar body noise too. Thanks also for the tip about not connecting the mag pickup to the condenser input, as the impedance differences would make that not work.

I also play bajo sexto, Mexican bass 12 string, and use a transducer, Dean Markley, that I fastened next to the bass strings underneath the top. It works pretty good and much better than the undersaddle pickup that it came with. I just used the same wire from the preamp/eq to connect the button style transducer after deleting the undersaddle. May try electret on that one too, as I like to use more than one input, especially for recording. I've tried using my AKG C1000s condenser mics for the Taylor for recording, but it captures too much pick noise for my taste.

Thanks again guys,
baja12

[Aura]

Changing to an electret condenser mic is not that streightforward,since it requires a small DC current to power it.The Fishman prefix may or may not output this supply,but then you can tap the 9v battery powering the Fishman with an appropriate value resistor in series to supply voltage to the mic or use an additional small battery if you choose to "bias" it with -voltage.