wiring help/suggestions

[Bluedragon]

So my Father and I are building our next semi hollow body emando. It's going to be an 8 string with a humbucker pickup at the neck and Fishman m400 bridge. What I was planning on doing is putting in a switch so the humbucker can be played in series or parallel, a volume and tone on the humbucker, and then a blend pot to mix in bridge or neck pickup.

Is this the best way to do this, is there an easier way to wire this with the same result? The M400 has a preamp in the jack, but should I look at a different preamp or piezo style bridge?

Thanks for the help.

[Martin Jonas]

Blending signals from a passive magnetic input with a signal from a pre-amped piezo is not straighforward, as the impedences will not match. I have got a mandolin in which I have fitted both a humbucker and an under-bridge piezo, and I have tried a number of ways of blending the signals. Simply soldering the hot wires together will not work, you will need to send both signals through a pre-amp capable of taking magnetic and piezo inputs. The preamp will take care of adjusting impedance and output levels (which will differ dramatically). The existing preamp in the Fishman probably can't do that. That leaves you with the choice of either buying a new on-board preamp with mixing capability, or of using an offboard mixer/preamp. I did the latter: my mando now has two mono jacks, one for the preamped piezo signal and the other for the passive humbucker. I can use either on its own without a mixer, or I can run both signals into a mixer and blend them there. I opted for two mono jacks, rather than a single sterio jack, as it gives me the option of working without a mixer when I only want one sound source.

Good luck!

Martin

[thistle3585]

I do something a bit similar on mine. I have a 3 way switch that is single coil/humbucker/out of phase with a volume and tone pot. I would do it as you suggested. I offer a headphone jack with an MP3 input, which is a little different than your setup, and use a blending pot with a switch on it.

I had a bunch of trouble figuring out the wiring to add the MP3 because of the impedence issue but finally got it after quite a few attempts and a lot of screeches. I don't have the wiring diagram offhand, but I could probably scratch it out for you.

[mandroid]

a bit more complex than using a a stereo TRS 1/4'' jack ,
with 2 signal (+) combined, 1 to tip contact, the other to the ring contact
and sharing sleeve, a common (-) ground ..

My 4 string electric Retrofit, uses RMC bridge pieces, and originally had a magnetic pickup.

It remains as 5 different signals out an 8 pin jack, thru a patch cable, to their , RMC made, Polydrive 2 black box.

it has a 9v battery in it to run a preamp, & tone and volume, for the 1/4'' output, + a 13 pin jack for Guitar synthesizers,

the installer tapped the 8 pin jack and put a 1/4'' jack in the PD2 box , it is a pass thru for the magnetic pickup.

so the 8 pin cable connects the instrument to the box and then the box is a splitter that can run 2,

actually several different things downstream .. Roland Guitar synths have a guitar output, that adds a 1/4'' mono output
and that, a pass thru, can run guitar pedal effects boards too..

[Bluedragon]

wow, my head is kind of spinning. Jerman I like the idea mp3 input, if you have the time to sketch it out I wouldn't mind seeing it.

The ploydrive sounds like a great setup, but it's probably more than what is needed, considering how this mandolin is going to be used.

Since the Fishman preamp can't handle the inputs, and the prodrive is a little overboard is there another preamp I should look into? I think I want it to be an onboard preamp.

I'm half tempted to keep it nice and simple and do the 2 mono jacks, but why go simple when you can drive yourself nut, by making it too complicated.

[thistle3585]

I am using what is called the "tillman" JFET amp. It should work in your application. A website is http://www.hawestv.com/amp_projects/...fetpreamp1.htm The last page of the essay has a bunch of links on variations. Its pretty easy to build, but figuring out the wiring was a lot of trial and error. I'd like to get a pre-printed circuit board made but its cost prohibitive at this point. I think our applications are a bit different but you could probably utilize the JFET amp. I'm basically making an onboard version of the Vox Amplug.

[MANNDOLINS]

You might try this...I use it and it works great.
Fishman Powerchip

[rico mando]

if you are willing to use one of andrews saddle bridges you could try the acoustiphonics system . it is meant for guitar but might work for mandolin. i am going to try it on a baritone mando but i have quit building for the time beinghttp://www.graphtech.com/products.html?CategoryID=2

[thistle3585]

You might try this...I use it and it works great.
Fishman Powerchip

Thanks Jon. I hadn't seen the one from Fishman. That appears to be similar to what I am using but a bit more user friendly as it switches between the pickups.

[MANNDOLINS]

I really like the "smart jack" feature to.

[Bluedragon]

So for some reason my last post didn't go through.

Rico- the last mandolin we built, we did use the graphtech setup with one of Jerman bridge and it worked okay, I wasn't really impressed with the sound from the saddles. But when you blend the saddles with the pickup you really got some output.

Thanks Jon I think that was what I was looking for. (By the way my Father and I really like you mandolins)

Jerman- I might be able to laser cut some thin copper to use like a printed circuit board. I'll give it a try one of these days and I'll let you know if it works.

[Bluedragon]

Well months later we have finally finished the mandolin. I must thank everyone for their help. We ended up using the Fishman bridge and powerchip and Seymour humbucker neck pickup, wired to a push pull switch to switch between parallel and series. If I can figure out a way to get a good recording I'll post that later. Thanks again

[Ben Milne]

That's realy purdy lookin'n.
Congratulations!

[Ed Goist]

Really cool looking Trevor. Congratulations!