Acoustic Pickup in Tune-o-matic?

Subject: Acoustic Pickup in Tune-o-matic?
From: Richard Bridge
Date: 02 Jul 13 - 07:55 AM

One of my beloved Hagstrom J-45s poses some curious problems.

She is a very rare later one - redburst with bolt-on neck (bolts through the back like an electric guitar - and a HUGE neck block). Some of the J-45s of that period came with a saddle that was very like a Tune-o-matic. She is one. It's a bit like some of the 60s Gibson J-45s in which the moving assembly is height adjustable on two thumbwheels (moving on two threaded inserts in the outer bridge-plate) - but in this case two screws come through the moving part like a tune-o-matic in stead of there being usable thumbwheels - and also the intonation of each string is adjustable with individual screws on the soundhole side of the bridge - just like a tune-o-matic on an electric.

Now at some point someone has made her pluggable. Quite the nastiest install I have ever seen or heard. There is a volume control that comes through the shoulder of the guitar and inside it a little one -transistor preamp (complete with hiss and hum). The transistor is about the same size as a 2N2926 but it's metal bodied like some of the early tall To5 cans. A very simple preamp - probably not as many as 20 components on a factory board (not verobard). No name I can see - a logo that MIGHT be "RS" and a legend that says "made in the UK".

This thing is fed by two apparently contact pickups - small - that are bedded into the bridgeplate from the outside. Maybe 3/16 of an inch across, mostly round (a little bit of a flat on the largest part on one side) with a wire on each that goes through the bridgeplates and then join up at the preamp. They look a bit like the simplest K&Ks but are smaller.

The sound is ghastly. Thin, scratchy, no bass even with 15Db added at teh mixing desk, and a tinny thin honk slightly tamed by taking 6Db off the treble at teh desk and putting a bit of a scoop in on the midsweep at about 1.5k. Not loud, either - by the time the guitar is getting audible the hiss and hum and buzz from the preamp is all too evident.

Of course the adjustable saddle is not exactly like a tune-o-matic. The post hole spacing is 3 and 1/16 not the tune-o-matic 2 and 15/16 but the string spacing appears teh same.

Here are pictures of three modern vibration bridges.

Cheap one http://www.ebay.co.uk/itm/330927926247?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649

Eyewateringly expensive Fishman (with the lead left out of the picture!) http://www.fishman.com/products/view/tune-o-matic-powerbridge-pickup-1

LR Baggs equivalent http://www.stewmac.com/shop/Bridges,_tailpieces/Electric_guitar,_Tune-o-matic_bridges/L_R_Baggs_T-Bridge.html


You will note that Fishman recommend their horribly expensive preamp as well.

Has anybody tried any of these - in an electric guitar or better still an acoustic? What preamps has anyone tried?

I would have to modify any of the modern ones by filing on flat ears (to get them low enough) and filing the post-holes sideways - but I reckon I could manage that.

Subject: RE: Acoustic Pickup in Tune-o-matic?
From: Stanron
Date: 02 Jul 13 - 09:08 PM

Over the last few decades I have played with piezo pickups with a certain amount of success. There are two important points required for their successful use. First these pickups work best when under pressure. This is why acoustic guitars have their pickups under the saddle. The strings press the saddle down on to the pickup and onto the guitar front. The increase of pressure gives a big increase in signal.

Second is the output from piezo pickups does not match the input of mixers or guitar amps. I'm probably going to get these figures wrong but the basic idea is right. Microphones work into 200, or is it 500 ohms resistance? Guitars work into 50, or is it 500 kilo ohms resistance. The point is that piezos work best into 2 to 5 plus meg ohms resistance. Put them into less and the sound is shrill and weak.

Another opportunity for me to be shot down in flames here, but one solution is to put a 2 to 5 meg ohms resistor in line with the output and then pre-amplify that so it gets heard through the amp, but the better solution is to get an impedance transformer circuit to match the piezo to a mixer or guitar amp. These circuits are quite simple, an 8 contact IC and 3 or 4 resistors and capacitors. They can be found online are within the capabilities of the hobbyist. I've done loads of these in the past buyin g the stuff from Maplins UK. I've even made my own pickups. I've probably got the old circuits filed somewhere if you would like to try them.

Subject: RE: Acoustic Pickup in Tune-o-matic?
From: Richard Bridge
Date: 02 Jul 13 - 09:26 PM

I have stuff that will present a high impedance to the pickups - but had sort of guessed that the existing preamp probably did that, or was so intended. I imagine it's worth a try hooking them up to a different preamp.

There is no way that the existing little pickup things could ever have been under pressure from the existing removable tune-o-matic saddle assembly - but I agree pressure on piezos results in higher output: the same pickup is shedloads louder in a 12-string or a mandolin - about 20db up in comparison with a 6 string I'd guess.

Subject: RE: Acoustic Pickup in Tune-o-matic?
From: Stanron
Date: 02 Jul 13 - 10:20 PM

If your bridge is the same as the images you linked to, then you will have a separate tailpiece. The bridge does not have to deal with string tension, just the downward pressure. If this is so then the metal bridge could be replaced with a similar sized piece of ebony or rosewood. A slot could be routed in that to take a saddle, an undersaddle acoustic pickup might be fitted under that and connected to a standard acoustic guitar preamp. You would loose the tuneamatic bit and have to rely on standard acoustic saddle compensation. No big deal.

The undersaddle pickups/preamp deals from China were very reasonable last time I looked. If you don't want to hack the guitar about to mount the pre amp you could look at a belt mount for it.

Subject: RE: Acoustic Pickup in Tune-o-matic?
From: Richard Bridge
Date: 03 Jul 13 - 12:48 AM

I have a pinbridge. Let me see if I can find an image of this particular Hagstrom J-45.

Subject: RE: Acoustic Pickup in Tune-o-matic?
From: Backwoodsman
Date: 03 Jul 13 - 01:42 AM

Why not just strip out the old gear and put a K&K in it? Less invasive than a UST, no quack, nice warm tone, and nothing between the saddle and the wood to interfere with unplugged tone.

Subject: RE: Acoustic Pickup in Tune-o-matic?
From: Richard Bridge
Date: 03 Jul 13 - 04:48 AM

I've never heard a K&K - I quite like the sound of an I-beam (so long as the glue does not go funny) but feedback is a problem. I've tried a number of other stickons and they were all shite. If I was going to remove the adjustable stuff I'd probably get a better unplugged tone and volume - but I'd likely go for a Headway Snake (not least in that I have two lying around!)

Oh, I should have mentioned another thing about the install - the person who did it took the neck off (which is at least easy, just like an electric guitar - and then appears to have used a large flat woodworking holecutter to make a "slot" in the neck block which (if it had straight and parallel sides and a straight flat bottom) allows a PP3 or similar to be slipped in. Result - if the battery is a smidgeon oversize or swells, you have to take the neck off to get it out!

Subject: RE: Acoustic Pickup in Tune-o-matic?
From: Backwoodsman
Date: 03 Jul 13 - 05:06 AM

I have K&Ks in three Martins and a Lowden, and they sound superb. If, as I am, you're playing solo or in a band with other plugged 'acoustic' instruments, K&K is a good way to go - very natural-sounding. If you're playing in a loud rock-type electric band, they are less successful due to the usual feedback issues that under-soundboard PUs suffer from.

K&Ks are passive (no f***ing battery in the guitar - yippee!) but benefit from a good matching-impedance outboard Pre-amp. I have an Orchid Muting DI (no volume/EQ controls) which I use when I trust the sound-man, and an Orchid Acoustic Guitar Pre-amp (volume, treble, middle and bass controls, and muting button) for when I don't. The latter device mounts on my mic stand. As you'd expect, K&K also produce a range of DI/Pre-amps, and there are others that do the job well - Redeye is one that springs to mind, Headway do one that has switchable input impedance and will match too.

The problem is, of course, that this kind of stuff is constantly developing, new improved gear coming along almost daily so, whatever one goes for, it becomes obsolescent almost immediately.

Subject: RE: Acoustic Pickup in Tune-o-matic?
From: Stanron
Date: 03 Jul 13 - 04:34 PM

I found an image of the Hagstrom J-45. Tailpiece and tunamatic bridge as you described, but now it makes sense. Have a read of this article.

http://www.frets.com/FretsPages/Musician/Mandolin/LtMandoBr/ltmandobr.html

You were right about the improved sound. If you could make, or have made a bridge like Frank Fords your Headway snake could be built into it. If your pickup will fit between the pillars of your existing bridge then a piece of rosewood or ebony or even maple or sycamore could be slotted to take your pickup beneath a convential acoustic sdaddle, and the complete unit placed between the pillars. Lots of options really.

Subject: RE: Acoustic Pickup in Tune-o-matic?
From: Richard Bridge
Date: 03 Jul 13 - 04:45 PM

Yeah, mine is not tailpiece, it's pegbridge. Off to look at the piccies!

Subject: RE: Acoustic Pickup in Tune-o-matic?
From: Richard Bridge
Date: 03 Jul 13 - 04:51 PM

PS - more mass = lower frequency (all other things being equal) - think about pendulums.

Subject: RE: Acoustic Pickup in Tune-o-matic?
From: Stanron
Date: 03 Jul 13 - 07:25 PM

In his article Frank Ford suggests that the greater mass in a bridge increases its inertia in response to string movement. This increases absorbtion at the neck end which results in improved sustain but loss of volume. His site is my number one place to check about instrument repair and set up.

Subject: RE: Acoustic Pickup in Tune-o-matic?
From: Tootler
Date: 04 Jul 13 - 02:24 AM

Richard, you should know better.

The frequency of a pendulum swing is independant of mass. It's the length of a pendulum that determines its freqency.

In the case of your bridge, it's the inertia that's key.

More mass = more inertia, therefore it takes more energy to set the bridge vibrating in response to the strings. The higher frequencies will be preferentially absorbed so a higher mass bridge will lead to less volume but better low frequency response. Conversely, reducing the mass of the bridge will give more volume and a brighter tone.

Subject: RE: Acoustic Pickup in Tune-o-matic?
From: Richard Bridge
Date: 04 Jul 13 - 03:04 AM

Yes tootler you are right - oops. But natural vibration frequency of a body, the return force of which is a spring (like a guitar string or indeed the top of a guitar IS dependent on mass.

That rules out going for one of the electric guitar tune-o-matics I linked to - my movable assembly is lighter than those, being hollow (those are solid).

I think I will have to go one of two routes - one being a cradle that holds a plastic or bone saddle (with an undersaddle in it). I have something like that in one of my mandolins and it is definitely loud but the problem has been getting the EQ right.

The other would be to retain the movable assembly but try first a different pre-amp (very high impedance) and second other stick-ons. I can test the first idea by using an old valve PA head I have - HUGE input impedance (or maybe a couple of belt packs I have - I think they are 1 meg input impedance, might be 3) but most stick-ons sound wholly vile and I am not paying out K&K money just to test a theory.

Subject: RE: Acoustic Pickup in Tune-o-matic?
From: GUEST
Date: 04 Jul 13 - 03:56 PM

Get yourself a JJB Prestige 430C 4way transducer and a L.R. Baggs 'Venue' pre-amp used. You're in for about 300.00-350.00USD and the sound is exquisite. Regardless of what instument one uses this combo to amplify. I drank the K&K koolaid to the tune of 180.00 installed on my mandolin. Sold it and bought the JJB Prestige 430C and am REALLY glad I did. The Venue pe-amp has an effects send and return option if one needs more processing, but I run the eq flat and use a Boss bass 10 bd eq ahead of the pre-amp for the mandolin. I pull the top eq slide all the way down and put the 'smile' on the eq from there. Depending on the room I pull or push the mid-range, but rarely have to touch the highs or lows. My mandolin is a Kentucky KM-160S...not exactly top of the food chain, but sounds like a 5,000.00 Collings w/this rig. The reason I run the eq ahead of the pre-amp is because the Venue only has 3 bands...not enough to clean up a mandolin.

My guitar is an '87 Alvarez DY-39 w/an L.R. Baggs transducer out of an old Seagull I bought at a pawn shop for 60.00. It kills. Needs a 9V battery. Had the tech cut a hole and install an 'easy access' battery holder like an Ovation or Adamas next to the eq rig. The eq/processor required a hole as well. As it wasn't a Lowden, Collings or an Olsen, but a 400.00 beater w/a solid top and laminated sides and back I had no qualms. Also a Joe Mills mic wired to the transducer volume/eq/processor for an extra 100.00. The combination is amazing. My residence is in Nashville where everybody hates EVERYTHING, but I've gotten a few(very) compliments on my 'sound' from other pickers. To get even a shrug in NV is a standing ovation anywhere else. :-) Well, except maybe NYC or LA.

The guitar is run through the 'effects input' on the Venue which gives me volume control, but no eq options. The transducer controls on the guitar give plenty of eq/processing to where I don't need it. In addtion the Venue comes w/a xlr send for a PA option and a 1/4" out for a stage monitor if desired.

The JJB Prestige 430C is a GREAT alternative to a K&K at roughly 2/5 the price for a better sound IMHO. Sorry if this post is lengthy as I don't know your budget or level of persnicketiness regarding your sound. My needs run to accompanying singer-songwriters, showcases, studio work, touring, to my own acoustic trio in the toughest guitar town on earth so I HAVE to be particular. If needed I use a Trace Elliot 200w acoustic amp...I doubt you want to go there. One practically has to take out a 2nd mortgage. But, it WAS tax deductable. Even the interest on the finanancing.

Subject: RE: Acoustic Pickup in Tune-o-matic?
From: Richard Bridge
Date: 04 Jul 13 - 09:52 PM

Thank you guest, that is very interesting. I will do some research. I have various combinations, but by and large people out front seem to like the Headway Snakes the best. The problem with this particular Hagstrom is the curious tune-o-matic bridge and the existing contact pickups and the existing pre-amp.

I also have problems amplifying my main mandolin (to the extent that I do sometimes use a solid-body "electric guitar" type mandolin if major amplification is on the agenda). Apart from that I have a B-band undersaddle in a Kentucky flatiron and the problem is thump - even taking everything below 300 hz off on an EQ pedal does not always remove it - but it sounds fine on some PA rigs and not fine on others! The unplugged sound is way better than what I paid for it - but I'm not looking for a bluegrass sound.