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Topics - frenchji

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I'm working on restoring a '75 Rhodes suitcase with a Peterson preamp.  I recently had the preamp, amps, and power supply worked on and recapped.  Got everything wired up and plugged in and everything seems to be working and it sounds amazing!

I'm curious about the noise level, and what is an acceptable level though.   

Should I expect some noise, similar to a guitar amplifier, or should it be dead quiet?  For reference, when I take the harp into a DI (bypassing preamp), It's absolutely quiet with no discernable noise.  When outputting into the suitcase speakers, I'm getting a little bit of buzz, similar to unplugging an electric guitar from an amplifier.  The "buzzing" or "hum" is consistent in level regardless of eq and volume.  A pair of the speakers also happen to be brand new, so I think I can eliminate the speakers from the equation.  The noise remains when unplugging the harp from the preamp, so I don't believe this to be related to the harp.  There is no noise when disengaging the preamp by unplugging the 4-pin cable.  This leads me to believe it's within the preamp?  That being said, there's little to no buzzing / hum on the headphone out and external amp out.

Again, the noise is an acceptable level, so it's possible I'm being a little too "OCD".

Below is a link to an audio file of the hum or buzzing I'm getting.

https://drive.google.com/file/d/1Ldcmc_OrvR2LdLSYYZBexQGjb8TM_w8L/view?usp=sharing

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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!

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I recently acquired a '75 Rhodes Mk1 Suitcase model and I couldn't be more ecstatic!  I've always wanted a Rhodes and found one that was semi-affordable, knowing that I would have to repair some elements.  I don't need or plan on restoring to exact era specs but I want to at least pay "homage" to the original design.

I'll start with the pros:

Directly from the harp this Rhodes is dead quiet and sounds exactly like how I imaged a Rhodes should!  There seems to be no pickup issues and besides one sticky key, plays nicely.  I might replace the grommets but I won't need to replace any bushings for the time being, although, I suspect that would be beneficial.

Now for the cons:

No Tremolo!  When Tremolo is engaged (or disengaged as well) the bulbs don't appear to light up.  Might be as simple as replacing the bulbs?

One of the notes barely has any sustain.  The tine and tone bar look fine.  This is why I might replace all the grommets as mentioned above.

Only one side of the speakers work and you can tell in the pictures that one of the amps needs some work.  There is a very obvious blown resistor on one of the amps which I'm assuming was caused by a temperamental/faulty germanium transistor?  The amp is very noisy but I'm assuming a large part of this is the faulty power amp.   

There is quite a bit of corrosion in the cab portion of this piano, as you can see in the pictures.  Miraculously, the speakers appear to be functioning though. 

Now for some questions:

Should I attempt to repair the power amps or should I buy a brand new set from the few people who make replacements?  I'm fairly confident in soldering so I'm open to DIY if possible, is this something I consider attempting on my own?  Doing a simple re-cap job I'm confident I can do just fine, replacing the germanium transistors with silicon might be something else though.  If I do buy replacement amps, which ones should I consider?

What is the best way to test the speakers to make sure they are fully operational?  I obviously can't test with the amps since one is broken and the other looks like it took a swim.

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