Rhodes Suitcase - Mixed Speakers (Ceramic / Alnico)

[frenchji]

I'm in the process of restoring a '75 Rhodes Mk1 Suitcase piano.  I found out one of the original CTS Alnico speakers is completely dead.  When measuring with an Ohm meter I get nothing and when performing the 9V battery test, I get no sound.  Three out of the Four speakers work (hypothetically), I should consider myself lucky!

I'm looking to replace the faulty speaker with a ceramic, something such as the Eminence Legend 1258 or the Jensen C12N to change it up a bit.  I noticed that a 12" - 32ohm ceramic speaker is hard to come by, so it looks like I'll have to replace these speakers in pairs.  This is okay with me as I'm not looking to restore to original specs.   

What I am concerned about is how this will effect "Vibrato".  I'll have to wire up the two ceramics (8 ohm) in series on one amp and the two alnicos (32 ohm) in parallel on the other amp, if I want to mix speaker magnet types and get to 16 ohm.  Unfortunately, I haven't had a chance to test the amp part of the Rhodes as the electronics were faulty and needed repair, so I have nothing to go off of. 

Will this sound weird if I have the "Vibrato" effect panning between Alnico and Ceramic speakers?  Am I better off replacing all four speakers for consistency?

Update (07/29/21): I just installed a pair of brand new Eminence 1258 speakers on one of the amplifiers and so far I'm impressed!  I believe these to be a perfect companion pair of speakers with the original alnico CTS speakers.  They sound fairly similar actually, with the 1258's being a bit "clearer" and brighter, which is what I expected.  The Tremolo (or vibrato?) doesn't sound odd at all with two difference speakers.

Unfortunately, my recording interface is being repaired as we speak so I have no clips to share at the moment.  I'll be sure to do so once it's back from the shop though!

[pianotuner steveo]

I wouldn't use a 9v battery to do the test, a 1.5 V is more than sufficient and shouldn't harm the speaker.
For anyone that doesn't know, you can test polarity of an unmarked speaker with a battery. This test also tells you if the speaker is working or fried.. If the cone moves outward with the battery connected, the pos end of the battery is connected to the + terminal. If the cone moves inward, it is reverse phase.  If it doesn't move at all with a good battery, the voice coil is likely fried.

This is useful for correctly phasing mismatched speakers.

[frenchji]

I wouldn't use a 9v battery to do the test, a 1.5 V is more than sufficient and shouldn't harm the speaker.
For anyone that doesn't know, you can test polarity of an unmarked speaker with a battery. This test also tells you if the speaker is working or fried.. If the cone moves outward with the battery connected, the pos end of the battery is connected to the + terminal. If the cone moves inward, it is reverse phase.  If it doesn't move at all with a good battery, the voice coil is likely fried.

This is useful for correctly phasing mismatched speakers.

Well... that's certainly interesting information.

[Will]

Interesting topic. My second-hand suitcase Rhodes has new speakers, all 4. I've always wondered if those were the best match for the cabinet. They sound good to me but I never heard the original version to form an opinion.
Tell me if I'm wrong ...
The design of a cabinet depends on the characteristics of the speakers. Nowadays, special software is dedicated to their design. Replacing the original speakers with new speakers requires that their characteristics be close to the original, or suitable to the cabinet.
Is there a place where we can have the characteristics of the original speakers? To compare with speakers on the market? And especially to those mentionned by Frenchji (which I also found on the web as successors to the first)?
Or isn't it that important ?
There was a webpage about the speakers on the Rhodes website, but it has been removed...

[frenchji]

Interesting topic. My second-hand suitcase Rhodes has new speakers, all 4. I've always wondered if those were the best match for the cabinet. They sound good to me but I never heard the original version to form an opinion.
Tell me if I'm wrong ...
The design of a cabinet depends on the characteristics of the speakers. Nowadays, special software is dedicated to their design. Replacing the original speakers with new speakers requires that their characteristics be close to the original, or suitable to the cabinet.
Is there a place where we can have the characteristics of the original speakers? To compare with speakers on the market? And especially to those mentionned by Frenchji (which I also found on the web as successors to the first)?
Or isn't it that important ?
There was a webpage about the speakers on the Rhodes website, but it has been removed...

I think that would be tough to do since the speakers in the Rhodes varied so much.

That being said, I do think I'm moving forward with one side being original (alnico) and the other being ceramic.  I'll be sure to record this once I'm finished so everyone can hear the differences.

[frenchji]

Replying because of post update!