Wurlitzer pickups and harps - the design concept

[PhatBanshee]

Hello all,
I, like other members on the forum, will be attempting to built my own EP. This is primarily because for a second hand Wurlitzer or Rhodes in England, you're looking at upwards of £5000 and £3000 respectively, and as a teen with shallow pockets that puts them definitively out of reach for me.

Still working on the design concept but so far I'm thinking a Rhodes-like action (for simplicity) combined with Wurlitzer-like reeds (for simplicity, if you see where I'm going with this). The only bits remaining uncertain in the design are the pickup system and electronics.

In light of this, I have a few questions:

1. Are there any obvious flaws I have missed in the design concept so far?
2. Would the Rhodes action hit the reeds too hard given that it's made to strike tougher tines?
3. How would I wire the pickup plate to an output? Would I need to wire the harp to the same output for it to work?
4. Any tips? I'd be particularly grateful for any input on the electrical and electronic side of things as I'm pretty clueless in this area but so keen to learn.

Thanks so much!

[steste]

Ciao, about the point 6 i suggest you to build just one key before start to build the entire piano.
Just a stand alone key w pickup tine and everything and with his you can experiment for real-
Happy that you do this creative project good luck have fun!
Stefano - Rome

[PhatBanshee]

Thanks Steste!

That's exactly my plan, glad to hear you would do the same.

For anyone wondering, the current point 4 used to be point 6 before I edited the message.

To add another question:
5. Why do websites like Vintage Vibe talk about the design and modification of the harp being a "mathematical nightmare for the layperson"? Isn't the harp just an electrically grounded mounting plate for the reeds opposite an electrically charged pickup plate? Does it really need careful design and acoustic tuning?

[gotkovsky]

Hello PhatBanshee,

In Rhodes terms, I think the harp refers to the hinged baltic birch piece where all the tines and pickups are mounted on, not just the pickups. In Wurly terms, it's called the reedbar.

The design of this reedbar is probably one of the most difficult piece of the puzzle, and its pretty crucial that you understand what you'll be doing here. It's all about phase cancellation and resonant frequencies.

I built a hybrid copy of the Wurly 200A with Rhodes style pickups two years ago, I suggest you read the full thread as I encountered these problems myself. Here's the link: https://ep-forum.com/smf/index.php?topic=10401.0

I have a folder with lots of gathered information on the Wurly reed bar, I can share it if you want.

Here's an excerpt from one of Wurlitzer's patent describing the issue they also encountered, in scientific terms:

[cinnanon]

I replaced a Wurlitzer felt hammer with a Rhodes hammer (I 3D printed the adapter) and it sounded funny. That's where I stopped. The Rhodes rubber hammer just wasn't hard enough to get a Wurlitzer reed to ring out. There were more harmonics than actual sound output. Very metallic sounding. I also modeled a new reedbar that goes an octave lower because I dislike the highest octave of Wurlitzers. The swing of the reeds would have been an issue so I stopped there as well!

As for the mass issue, I always speculated that a steel reedbar would fix all resonance problems, but I have yet to try. I have friends with CNC machines and could easily write the programs, just haven't done that yet either!

[butterfingersbeck]

I have a Valente electric piano which combines a simplified action with reeds and passive magnetic pickups. The action is adapted from a hammer-action keybed designed for digital pianos - each key has a couple of extra levers, one for the hammer and the other for the damper, both activated by the existing dummy hammer.