Op amp for Piezo (Hamer Duotone)

[901]

I guess this must have been discussed around here from time to time, but I didn´t find that much.

I just got a very nice Hamer Duotone electric guitar that sports (as you can guess) a piezo bridge pickup.

Hamer has put an active electronic inside which in principle works fine, but is a little noisy. Although there is plenty of space in the electronics cavity in the guitar, they made up a SMD board. There is only one op amp on it and it´s a TL062C.

I know there are much better op amps available today. But which one could replace it? Of course it shouldn´t eat up too much battery life, sound nice and clean and has lowest possible noise.

Would a LT6234 do the trick? I read a recommendation for a LT1352 for bass electronics in another thread. Better?

[Minion]

Any Fet input opamp would be suitable ... no bipolars

[12Bass]

LT1352 sounds decent and doesn't draw much, but is bipolar. A piezo buffer likely calls for a FET input. OPA827 sounds quite good, IMO, but draws a lot of current for on-board applications and only works down to 8V (+/- 4V). Might be worth checking the data sheets from TI/AD/LT/National to see what fits your requirements. Even a TL072 would be an improvment....

[Jim Williams]

The 062 draws 250 ua. All the better for audio fet opamps suck more than that. I would use a AD8512A and replace the batteries more often. S0-8 only. The AD823 is another good one.

Jim Williams
Audio Upgrades

[901]

Just had a look at the AD8512A datasheet. Looks good! I´ll give it a try.

Thanks a lot!

[12Bass]

The AD8510/12/13 series definitely looks interesting. What do they sound like? At all similar to AD823? AD825? FWIW, I found the AD823 a bit harsh and lacking in detail. AD825 sounds good in certain applications, though IMO it seems a bit more colored than some of the other new chips (OPA211/827). Would AD8513 be a good replacement for a TL064 or TL074? Good quad op amps can be hard to find!

[Jim Williams]

They sound like the Bricasti M7, the only pro audio piece I've found those chips in. Casey managed to get pre-production chips before they were released. Working down the street from Analog Devices and using their DSP chips might have helped.
I had those AD8512's in the Bricasti 3 months before I could get samples.

That series was designed to replace the BurrBrown OPA134/2134 series. They don't have the zippy top end the BB parts have. They are smooth, quiet and very low offset. Most times they can be used without coupling caps and input bias current is also very low.

The BB OPA827 single fet opamp bests the AD8510, but the 8512 is the best dual audio fet opamp out right now. The AD8513 quads I use in the Alesis HD24XR mods that I used to use BB OPA4134 quads. The LME49740 quad is a better opamp if you can deal with bipolar inputs.

I have a bunch of dual to quad converter pcb's I use to "create" a better quad opamp. A couple of LM6172's makes a smoking quad. New stuff is coming out next spring from AD, they will have the dual to kill all duals out by march. AD sent me the info yesterday and I'm chomping at the bit for those...

Meanwhile, I have some new RF FET transistors with .8 nv noise. I put some into some mics along with .5 nv noise bipolar transistors and that mic is so quiet I can't detect any hiss up to + 60 db of gain! If I run that into my super low noise mic preamps I have a system noise far below anything I've ever experienced or heard. It's sort of weird hearing it, it's like there's some low level noise gate going on but you still hear everything so far down in level it's very strange. I can hear myself smile from 10 feet away! I hear the air moving, but no electronic hiss, none.

It's a golden time for analog development.

Jim Williams
Audio Upgrades

[12Bass]

Wow! Thanks Jim.

[Casey]

Originally Posted by Jim Williams

It's a golden time for analog development.

Once you get over the 24 bit Analog Devices part in the M1, I know you are going to rethink what a modern DAC chip can become when surrounded by the best of everything.

I am flat out surprised.



-Casey