Needing a new preamp for my Axis Super Sport with MM90's and Piezo

[caballero59]

Battery life is super short. I measured 17 miliamp current draw with battery installed and 5k resistance with battery removed and a cord inserted in the jack. This makes no sense according to ohms law. Also, a time or two experienced ferocious intermittent noise with the piezo. A quote from Ernie Ball is $205 for a new preamp that includes switches, pots, toggle, etc. all soldered in. I doubt if it's available without the peripheral equipment. Ouch! This is an expensive guitar.

 

[beej]

17 mA seems high, but I don't know what it normally draws. Does seem unlikely that the preamp is suddenly drawing more current, though that's certainly possible.

I'd probably check all of the wiring, starting with the output jack first. Could be that it's not disconnecting the ground when the cord is out; that the lugs have been bent over time, etc., which could explain both things. Ditto the other wiring- perhaps something is making contact where it shouldn't.

 

[tbonesullivan]

17 mA current draw honestly sounds pretty normal. Most simple stompboxes draw less than that, but many choruses and other effects are around 20mA

Did you check with EBMM to make sure that it's out of spec?

 

[caballero59]

17 ma gives about 14 hrs with a Duracell 250 mah battery but most users report much longer times.

 

[caballero59]

Scott

 

[caballero59]

The magnetics and Silent circuit part of the preamp is fine so I'm considering experimenting to see if I can route the Piezo leads directly to the jack and use an external dual-source preamp such as a Dtar Solstice and forget the internal piezo preamp.

 

[beej]

Responding to your deleted post- MM doesn't want a market for second-hand parts, so this is why you can't buy proprietary parts (e.g. the PCB) without returning the originals first. That has always been their policy.

You can also just send them the guitar- they may be able to fix something simple without having to replace the PCB (get a full tune up while it's there ...). Their bench rates are extremely competitive.

Personally I don't think $200 is unreasonable given what's involved, but that's really your call.

Yes, you can just route the piezo wires to the jack and use an external amp. There are also plenty of third-party preamps that would work fine.

 

[caballero59]

I suppose I'm a bit disappointed by all of this. I don't believe that $350 to repair a glitchy piezo output equates with "good value"?

 

[caballero59]

I need to say this. Billy in tech support at Ernie Ball has been great in trying to work with me. I learned today that the preamp design has changed and the updated version does not have the post soldered directly to the board. I may go with that because it sounds like that is a more universal preamp used in current guitars and should enjoy a long support lifetime.

 

[beej]

I thought you said $200 (your first post) not $350?

Anyhow ... "good value" is in the eye of the beholder. Who knows what's wrong with your preamp, but it's clearly and old part that's out of warranty and had use, so there obviously has to be some cost involved here.

And yeah, Billy is awesome!

 

[caballero59]

$350 if I send the guitar in and they did mention the preamp change is not trivial. But anyway, I isolated the problem. The piezo is not grounding properly through the piezo shielded cable but instead, is robbing a ground through the ground wire that is sandwiched between where the bridge is screwed to the wood body so the circuit was intermittent. Won't need a preamp but may need the pcb strip under the bridge which would be much cheaper.