Peavey w/piezos, looking for options

[gmoon]

Bought a Peavey Generation EXP ACM guitar last weekend, for a very good price. Has the Graph-tech Ghost piezo pickup system, also normal SSH mag pickups, and a hardtail bridge.

Nice guitar, action-wise. Feels solid. Condition is immaculate. Neck is a little fatter than my MIUSA Predator neck, but not as thick as my LP (still quite comfortable for me). Better slightly beefier than really skinny.

All the pickup signals go through the preamp. Eh! Feh. The normal pickups sounded choked, compressed, and were MUCH quieter than either the piezos or any other electric guitar I've got. Turn up the amp to get a decent "normal" sound, and the preamp hiss becomes VERY evident. Yeah, I tried various 9V batteries...

So...I only went two days before ripping out the piezo preamp and direct-wiring the regular pickups. Sounds great! The body cavity is shielded with conductive paint, and the pickups are decent (better than expected). Even the humbucker isn't an "icepick." Doesn't sound like a Tele, of course, but rather like a hard-tail strat.

OK. So I paid (considerably) less for the whole thing than a set of "Ghosts" w/ the preamp. How do I make use of these without the "tones*ck" factor? The piezos sound pretty good themselves for what they are, and even better in "mix" mode with the magnetics--but it's a "specialized" sound, and I would use it sparingly.

The stock selector switch is center-off, with the following schema to the preamp board:
-- GND to Select MAG only
-- NC for "mix" mode
-- GND to Select ACM only

Also, the preamp has a stereo output jack, too, so the MAG and ACM signal can be routed separately.

I think I could use a 3PDT mini-toggle to switch between full-on magnetic pickups (with a true bypass) and the mix mode w/the preamp. I could live with that--turn down the mag pickup volume if I wanted "full on" piezo.

Anything more complicated than that would require more switches, or more circuitry... If possible, I really want one option to be direct output to the mag pickups.

Any thoughts? Recommendations? Wiring suggestions? Alternate preamps?

Anyone use Piezos in a similar setup? Have you tried the "ghosts?" Do you like them?

[bigsbybender]

What I do with my Piezo instruments is use a stompbox EQ.  Leave the other pickups direct.  The EQ will act as a preamp/buffer and of course EQ for the acoustic-ish tones. Kick the EQ off for the regular magnetic pickups through your amp.

I have an old Kay archtop that I put a jazz-style floating neck magnetic pickup on, and then made a piezo pickup assembly for the bridge. This was my way of getting the best of both sounds. (also I didn't want to alter the guitar by cutting in for an onboard preamp)


j.

[G._Hoffman]

I've never been fond of the Ghost preamp.  I think their pickups are really good, but the preamp just sound kind of sterile to me, and I really don't like 9V preamps for piezos.  

The ones I do like are the D-Tar (which I'm not sure they are even making anymore), and the Bartolini Piezo Preamp.  Bartolini makes two, one for just the Piezos and one for the Piezo and the Magnetics.  Unfortunately, to get the Piezo only version, you would probably be waiting for a good 6 months, as it is a custom production piece for them (If you really want, I can order it for you, but be prepared to wait a LONG time).  That being said, when run on 18V, it is a LOT better sounding than any 9V system, and doesn't completely destroy the sound of your magnetic pickups (it still kills the dynamic interaction with the amp, of course, but it doesn't have that compressed ickyness most preamps have).  

From what I've been able to understand about it, the big problem with the 9V preamps is they can't handle the peak amplitude of the guitar signal, which is what gives them that compressed sound, and also distorts you high frequency stuff in a really unpleasant way.  An 18V system gives you double the head room, and tames a lot of the quack you get with piezo pickups.  


Gabriel

[G._Hoffman]

Also, it can help a lot (if you can) to use two amps.  Kind of a pain to carry around to gigs, but you can set up the amps to sound a lot better.


Gabriel

[gmoon]

Also, it can help a lot (if you can) to use two amps.  Kind of a pain to carry around to gigs, but you can set up the amps to sound a lot better.

Gabriel

Thanks, Gabriel. I'll check out the Bartolini preamp. Although a lag of months is a long time...

One option is adding a second output jack for the piezo (they originally came with a stereo plug that split into mono jacks, I guess). When I think about it, it makes more sense to tailor the settings on two separate amps, rather than trying for force-feed a good electric guitar amp the piezo output... Not that it couldn't work, or couldn't sound cool, if it was tweaked *just right*, but that probably wouldn't be the amp settings that sound good for the mag pickups. Plus the battery switch would be in the second jack, so it would never drain unless I actually plugged in for the piezo...

And with two amps, who needs the "mix" preamp setting?--the sounds are mixing acoustically in the real world.

I have a feeling the Generation preamp is a Peavey design, rather than a Ghost product. They call it the ACM II (acoustic modeling?) technology preamp. I think an earlier version of the Generation used a "powerchip" preamp...maybe Fishman?

@bigsbybender--

So you use an external preamp/EQ? I wonder what the output impedance of a piezo is... Would eight or ten feet of cable mess with the piezos?

Thanks for the info. Makes me want to try a mic preamp just for fun.

[Platefire]

Nice! I like. 3 tone Sunburst+ Tele Shape+ HSS+  I love the way a humbucker and the middle single coil sound together more than two single coils of the original strat quack. The H/S is a fatter quack! 

[bigsbybender]

@bigsbybender--

So you use an external preamp/EQ? I wonder what the output impedance of a piezo is... Would eight or ten feet of cable mess with the piezos?

Thanks for the info. Makes me want to try a mic preamp just for fun.

I use a relatively short cord to the EQ without trouble (~10ft.).  I notice problems with 15-20ft cords, but I usually don't move around much.

[G._Hoffman]

Thanks, Gabriel. I'll check out the Bartolini preamp. Although a lag of months is a long time...

The dual preamp I linked to is on their short list, so it is usually a matter of weeks, and Allparts frequently has it in stock, so only a week.  It is only the single preamp that is a long wait.  It is, in my opinion, clearly the best piezo preamp on the market, and I've tried most of them at one time or another.  (If it were entirely up to me, I would never use any piezos, but you have to give the customers what they want, you know?)


Gabriel

[G._Hoffman]

I think an earlier version of the Generation used a "powerchip" preamp...maybe Fishman?

Yup, that's the Fishman.  Not bad for a 9V preamp, but not my favorite either.



Gabriel

[gmoon]

Nice! I like. 3 tone Sunburst+ Tele Shape+ HSS+  I love the way a humbucker and the middle single coil sound together more than two single coils of the original strat quack. The H/S is a fatter quack!  

Yeah! Now that I've lived with it for a few days, it does have more "tele" (err, telepresence?) to the sound than I originally thought.

But PV set it up and the 5 pos switch is wired so the bridge 'bucker is split-coil for the combination (automatically). So I don't have that goin' for me (yet...) I'd like to hear the split (single) on the bridge alone, too! Maybe even more tele-like. With the mini-toggle unused, I think I can do it...

It's really very pretty, condition is flawless (that won't last, no doubt I'll bang into something soon.) Plays good.

[gmoon]

The dual preamp I linked to is on their short list, so it is usually a matter of weeks, and Allparts frequently has it in stock, so only a week.  It is only the single preamp that is a long wait.  It is, in my opinion, clearly the best piezo preamp on the market, and I've tried most of them at one time or another.  (If it were entirely up to me, I would never use any piezos, but you have to give the customers what they want, you know?)

Gabriel

I sorta feel the same way, but I'd like to at least give the piezos a chance.

Bartolini has a page with preamp installation instructions, and a couple of models are "unlinked." So those must be the special order single-preamps. All the rest are piezo/mags or mags only.

The easiest way to try this would be just to reinstall the stock preamp, and keep the two pickup systems totally separate. I'm afraid the PV preamp might load the mag pickups--it uses a single inverting opamp stage with Rin / Rf of 330K / 330K, flowing the 250K volume control. I can always look into better preamps if I actually like the piezos...

There's also this ultra simple FET piezo preamp.

If I add a dual jack / jackplate, should I use a plastic jack for the second output? (ground loop avoidance)

I use a relatively short cord to the EQ without trouble (~10ft.).  I notice problems with 15-20ft cords, but I usually don't move around much.

OK, now that would be the simplest way to experiment... Just run a shielded cable out the back and into an external preamp (except I don't have one that's quiet, other than a mic preamp that's part of a M-audio setup).

[gmoon]

Well, it took a while, but I finally reinstalled the piezo preamp and added another jack, keeping the normal pickups and the piezos separate.   Sorry for resurrecting an old thread...  

The bottom knob controls the piezo volume only. The other two are volume/tone for the regular pickups. The switch (small toggle) controls the split humbucker: S S/S S S/S S, S S/S S S/H H, S S/S S S/S H. I can't say enough good things about these Peavey pickups; they are quiet, articulate and very dynamic. Man, they sounded horrible through the preamp!! (which was the only way to access them before).  I've installed several Fender and Seymour Duncan pickups lately on another guitar, and these Peavey stock PUs beat them all. Other PV PUs I've heard are at best so-so.

Now that the piezo is back, I don't think I'll use it much. It does sound kinda cool with two amps. But not cool enough to be a big deal. And using the piezos does introduce a little noise to the regular pickups. Go figure...