Preamp recommendations?

[Dogue]

I'm looking for recommendations on preamp circuits for a specific application:

I recently acquired a Hohner Pianet T.  The Pianet T is a passive electric piano which employs 60 electromagnetic pickups in series to amplify the vibrations of plucked reeds.

The output of the pickups go to a transformer, which goes to a small capacitor, and the signal is output to a 1/4" jack.

If I'm measuring this correctly, the DC resistance of the pickups total about 38 Ohms, while the output from the transformer measures about 5.1k.

In general, the output of the Pianet Ts is around 100 mV, so it is a relatively weak signal.

Can someone please recommend a preamp circuit to amplify the output signal and do any requisite buffering so as to minimize hum/noise?  Thanks!

[frequencycentral]

Pianet T - nice. I always hankered after one, but the impossibility of the sticky pads replacements put me off. I have a Rhodes Stage 73 MkI and a Wurlitzer EP200a, both of which sound great through a tube amp. You might consider a tube boost, or maybe the classic Dyno-My-Piano preamp designed for Rhodes.

Tube boost/overdrive: http://www.diystompboxes.com/smfforum/index.php?topic=63479.0

The Dyno schematic is in this thread: http://www.diystompboxes.com/smfforum/index.php?topic=29855.0

[Dogue]

There are replacement sticky pads now available from clavinet.com.  I just ordered a set, but they haven't arrived yet.  I've heard good things about them, though.

Thanks for the suggestions.  From what other Pianet owners have said, a good preamp will raise the signal level while minimizing noise (as opposed to just increasing the gain, which raises both).  Is this to be expected from one of these preamp designs?  And if so, why is this?  Is this an impedance/buffering issue?  Sorry for the newbie questions!

[anti-idiot]

Deleted by me.

[thedefog]

I've been looking for one of these on eBay recently. The size of these, along with the affordability and sound is a big plus. I'm surprised they weren't more popular.

[petemoore]

  100mv should be easy enough to boost up.
  What is there or could be put there for a power supply?
  Tubes are nice because...they sound like tubes, but the PS can be a bit of a challenge in different ways, in such cases where it is a challenge, SS might be the good choice.

[Ripthorn]

If you want to boost the signal while keeping the noise low, put in a noise gate before something like a simple tube gain stage (or two of them) so that the noise gets cut first, so only the signal gets boosted.

[Dogue]

Thanks for the further suggestions.

I've wired up but not yet tested a Dyno preamp.  The one question I had concerns powering it -- what would be the preferred source, 2 9Vs with a regulator?

I've been looking for one of these on eBay recently. The size of these, along with the affordability and sound is a big plus. I'm surprised they weren't more popular.

Yes, for me it was all about the portability.  Seems to be about the only real electric piano I could realistically take on the subway.  The demand may be stepping up.  The last few on eBay have gone for more and more money.  There certainly are some deals on Craigslist occasionally, though.

[Dogue]

I made a Dyno preamp, and the bass boost and overtone controls add a lot and, as to be expected, boost their respective frequency ranges quite a bit, though there isn't much overall boost.  I can only assume that either 1) that is as intended, or 2) I messed something up.  I am now choosing to assume 1), so I've wired up a Stratoblaster and am planning on using it in front of the Dyno, and then a Ghetto Stomp clone after the Dyno.  Seem like a good solution?

[tombola]

I built a Vibrocaster (valvecaster tube drive + trem) for exactly this. Works pretty well.