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Topics - Cookymonster

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The Fender Rhodes Electric Piano / Fixing the harp on the treble side
« on: April 30, 2021, 09:36:55 AM »

I was just wondering.
The positioning of the treble part of the harp.  Is it always best to fix it where the tones ring loudest ?  There is not the same movement space as on the bass side.
It can bemoved between the hammer getting stuck on the tine block and no sound of the small tine. So about maximum an inch / few centimeters.   As the sound of the treble section can not be customised like in the middle section, I always start looking  for the loudest, best ringing treble tones and then fix the harp with one screw.  After that I start shifting / moving the harp  for best tone / strikeline ... not always the loudest tone... but a lot of times, though.  Thanks for advise.

Sorry for my English. It's not my first language.

My new 1975 suitcase – Peterson- Rhodes  is a great instrument  in very good condition.

It is “all-original”  except of course for the small parts (grommets,
hammer-tips, action mod, washers, felts..)
I intended  to keep it that way.  

But to be honest, some flaws and issues kept bothering me.
Like a lot of old suitcasesit suffered from modest volume, unwanted distortion, especially when pushing the volume, crackling noise, a bit of hum…
And of course the well-known  “muffled” suitcase sound...
OK, it’s charming in a way. But I would rather reach  that particular sound by turning my tone control
button to the left... but also be able to have some brilliance and transparency when it is turned to the right…

As I wanted to keep my suitcase original  I decided to “replace” some parts, rather than to repair or modify.
And I would keep the original components stored safely in a dry place.
Everything should be reversible.

So I replaced  the old alnico speakers for some new Jensen CH/Mod 12-50
I doubt this was a good choise. I will explain later.

I replaced the old Peterson pre-amp for a new  Vintage Vibe pre-amp
Great product, sounds like the old Peterson pre-amp, but without the noise, humm, crackling etc.

And recently I installed  the new amp modules designed by Mike

Fender Rhodes 7054 “Peterson” Amp Redesign Kit

Mike offered two things:
-              Sending just the printboards with the transistors
-              Installing  the PCB’s and transistors to my current Peterson modules (which I had to send to him)

As I wanted  to be reversible, there was only option 1.
So I ordered a pair of modules from Borish electronics.

Meanwhile I ordered a pair of Indonesian good quality heat-sinks for about
20 $, shipping included. They are a bit shorter but thicker, but look and feel very well.

The heat-sinks arrived a few days later.
Belgian Customs clearing kept the amp modules for  more than one month   :o :o >:(  tsss....

Anyway.After this month, both PCB’s arrived well, together with 4 new silicon transistors and fuses.

I  have very modest notice of electronics.
On Borishelectronics’ website the modules are called  “drop in replacement”.

This would surely be the case if  I would have sent in my old Petersons, to receive ready-made modules.
But I had to install the transistors and do some wirings.  Also I had to check  for regulating the bias and offset.  :-[
After Mike’s  first e-mail with instructions regarding this,  I concluded I  would  depend on my local amp tech.

But when the modules finally arrived,  my amp tech  went on holidays…for three weeks.  
I have been patient enough with the customs - delay,  so I decided to try it myself.

To install the transistors to the heatsink, well there was Youtube and Google  ;D.
It looked pretty obvious, so I felt rather confident about that.
The wiring made me doubt a bit. I was not sure about 2 wires.  (only 4 wires, one wire is ommitted in this design)

But I managed to install them.

I was very eager to test my modules.
I don’t have a “variac” like Mike suggested (who does anyway?) so I plugged
them directly into the power section of the suitcase…with speakers connected of course.

You can see the new modules attached to (temporary long wires  connected to) the Power supply.
And in front the old Peterson modules.

I kept the power switch between my shaky fingers in case  the modules would show up as smoke generators  ;)
What was / is  the result ?
Just one short sound ? With some visual firework effects ?
Or will I finally  make my point and just describe the qualities of the amp modules ?

 That is for my next post…if you still would want to read it. It is already
a lot of writing for me and reading for you ::)

This was the UNBOXING part. Next is the review.  Hope to see you back...

Preamps, Modifications & Upgrades / Suitcase replacement speakers
« on: September 26, 2016, 04:40:35 PM »
My old 1975 suitcase (Peterson amp) still has its original eminence alnico 12 inch speakers.
Nice vintage sound, although I think there is room for some improvement.
My tech (specialist amp repairman) indicates that new speakers or new cones may result in much better mids and highs.
I found the Jensen MOD12-50 at a very reasonable price.
However, according to the specs and sound samples on the Jensen website, the slightly more expensive (but stille affordable) C12N  should produce more articulate mids and highs...what an old suitcase may be missing a bit....


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