Pre Amp Assistance

[Macovitski]

Hello, Mandolin Cafe Folks...

Macovitski here...this is my first post so bear with me. I have been a long time flat picker on the guitar and lover of bluegrass. As part of duet I play in, I decided to add the mandolin to the mix. I was advised by my local music store to try out the Eastman 305 and 315 and I purchased the 315. I am very very happy with the instrument. I purchased it before Thanksgiving and my guitar does not venture much into the light of day anymore...I might be diseased.

So, after Christmas, I had the store install a Fishman m100 so I could play plugged in with my buddy and groups and such. I am currently playing it through a Marshall AS50R with no pre-amp. The Fishman is amazingly sensitive but the sound is thin and a bit shrill if I add any volume. There are also some feedback problems. The instructions with the m100 recommend a preamp but do not recommend any models. I am a newbie with electronics and all the info on aura systems etc. are giving me a headache. Can anyone recommend something simple and effective?

[Atlanta Mando Mike]

All the bells and whistles
http://www.amazon.com/LR-Baggs-Acous.../dp/B002LFCDPM

Great, high quality but simple
http://www.amazon.com/Fire-Eye-Devel.../dp/B0089EUZ4A

Fishman loudbox amp with built in pre amp- very cool option and can really dial in tone
http://www.sweetwater.com/store/deta...X4gxoCzr7w_wcB

The pickup of choice for most pro's these days - warm sound, inexpensive, great choice
http://www.amazon.com/K-Mandolin-Twi.../dp/B00CX6HQ06

[Tim2723]

Hi and welcome!

Michael has given some of the top picks. The Baggs Venue has all the essential tools all in one place. If you're already happy with your tuner and don't want to spend quite as much, the Baggs PARA DI remains a perennial favorite among the mandolin crowd.

http://www.amazon.com/LR-Baggs-Para-...=baggs+para+di

Even when a pickup works OK with a given amp, a preamp is always good to have. They solve the problems you're experiencing plus a hundred problems you haven't run into yet but will sooner or later.

Again, welcome.

[almeriastrings]

So, after Christmas, I had the store install a Fishman m100 so I could play plugged in with my buddy and groups and such. I am currently playing it through a Marshall AS50R with no pre-amp.

In fact. No - you are not.

This is a true acoustic amplifier. It already has a high quality, high impedance (1M) preamplifier designed for piezo transducers built in. That is what you are using.

These are also a nice sounding amp (I had one myself, some years ago). They do not require any external preamps. If you do add one to the Ch.1 jack, you would be cascading them, which is rather poor practice and can cause clipping problems. You are using a bridge piezo, and these are notoriously 'harsh' and thin sounding compared to a soundboard transducer, so I would look there, first. The built in preamp on the Marshall acoustic amps is perfectly adequate for most transducers, but getting a really decent sound from an M100 is an uphill battle in my experience, sorry to say - no matter what preamp or amplifier you use.

[Mandobart]

Since the Fishman pickup is a piezo element, you need to make sure the impedance is matched to your amp's input. Piezo output impedance is around 10 megohms, and your Marshall is looking for mag coil impedance on the kilo-ohm range. That is the usual cause of the harsh tinny sound.

Search on preamps here on the equipment forum and you could spend days wading thru all the info and opinions. It comes down to how much do you want to spend and what features do you want. I've used an Art Tube, Behringer ADI, K&K Pure and now the RedEye. They all worked and improved the sound. The Art needed external 9 VDC power and was a little large to fit in my gear box. The Behringer could use a wall wart or battery and had some mix and filtering options, and has a balanced XLR out. The K&K is very convenient on the belt with volume and tone pots. Uses battery only. The RedEye gave the best sound of them all, uses a 9V battery or phantom power thru the balanced XLR, has a send and receive for effects/tuner and a solo boost. Lots of other good choices mentioned above.

[almeriastrings]

Since the Fishman pickup is a piezo element, you need to make sure the impedance is matched to your amp's input. Piezo output impedance is around 10 megohms, and your Marshall is looking for mag coil impedance on the kilo-ohm range.

No.

This amp was specifically designed to work with passive piezo transducers. It is not a 'regular' Marshall electric guitar amp. It is a very good quality acoustic guitar amplifier. It will also work with magnetic pickups, but the input circuit was specified for both passive and active piezo systems. The 1M input impedance is fine for the vast majority of such transducers (and is what K&K, among others) recommend for passive transducers. You can go higher... and there may be some audible effects, particularly LF extension, but 1M should certainly be adequate, if not entirely optimal for all transducers. If you are getting a truly lousy sound at 1M, increasing it is not going to make that much difference.

I've had people turn up with M100 bridge transducers and even if you run them into a Headway EDB-2 (with 5M and even 20M) input impedance options, they still sound harsh and thin. I have found this to be a consistent characteristic of embedded bridge transducers vs soundboard systems.

The AS50R does not have phantom power on the mic XLR - the later AS50D does, so if you do decide to try a different preamp, you need one that is self-powered (or, insert a separate phantom PSU - which starts to get messy). Any external pre should not go into the Ch1 Jack, but needs to be a true 'DI' type that can successfully feed the 'mic' XLR. e.g., Baggs Para DI or similar. I would investigate alternate transducers before laying out that kind of $$, though, as you might still end up dissatisfied with the result.

[Atlanta Mando Mike]

I am unfamiliar with that Marshall acoustic amp and didn't realize it had a quality preamp like the Fishman Loudbox I mentioned. I agree with Almeriastrings. I linked to the K&K Twin internal pickup (My favorite true pickup for mando) in my earlier post because the M100 just isn't a good sounding pickup and that is likely the root of your problem. I would change that first and see if that fixes it. You can research pickup options on this forum as these topics have been discussed in detail over many threads.

[mandroid]

Along the same Lines.... I have a switch on the instrument Input of my Roland AC 60 ..

2 positions , Magnetic and Piezo for the pickup impedances of the sources...

[Macovitski]

I would like to thank all of your for your thoughtful responses. This certainly is an education. The root problem seems to be the M100 which is a little distressing considering I had it installed through the top and side of the instument. I am wondering how difficult it would be to change it out...my problem. On the plus side, I am currently playing popular tunes in a bar format and the sharpness cuts though the muddiest muddy. Eventually, though, I think I might need to change it out.

It is going to take some time to go through the details to your posts. Thanks, the newbie is indebted...

[almeriastrings]

You can always do a test run with soundboard transducers, just by a temporary fix outside, rather than a permanent fix inside. It will certainly give you the 'flavor' of the different options, and allow you to move them around to find the 'sweet spot'.

[lenf12]

You can always do a test run with soundboard transducers, just by a temporary fix outside, rather than a permanent fix inside. It will certainly give you the 'flavor' of the different options, and allow you to move them around to find the 'sweet spot'.

I never got past the external test run phase. It's not pretty but certainly works well. btw - this is a JJB Electronics dual head pickup available on eBay for ~ $20 (much cheaper than K & K) and attached with Blue Tak putty available at the office supply or hardware store. My first acoustic mandolin pickup was the aforementioned Fishman M-100 piezo bridge like the OP's and I could never get a satisfactory sound, always thin and shrill even with a Fishman Pro EQ preamp. Fortunately, the bridge saddle eventually broke (questionable quality ebony?) forcing me to seek a better solution.



Len B.
Clearwater, FL

[mandroid]

In a Bar band , the party will go on whether your tone is to your satisfaction or not.

If you want a concert stage quality Tone, I'd suggest an N+1 solution.
get a Mandolin that you really like for the tone acoustically..

Posting here you will still get a touting of each person's favorites ..
I like Schertlers Moving coil Dynamic Transducers .

[name dropping] a Week ago .. A Solo performance By Evan Marshall
His stage setup, used a combination of an external Schertler Dyn-M pickup

and A Rode NT3 microphone.. on a mic stand.