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91

Preamps, Modifications & Upgrades / Re: DIY Peterson preamp (tremolo) pedal

« Last post by JanneI on September 13, 2019, 12:55:23 AM »

 

The whole project started with taking a closer look at Vintage Vibes stereo vibe preamp, which I had purchased long time ago. I got interested in how it differs from the original Peterson schematic and by back-engineering I found out that the only difference was in the tremolo section (bulbs -> VTL5C1's). This simply been just some resistor value changes and a slew generator to simulate bulb behavior.

I opened up their power supply (that red one) and noticed that there's only that mean well supply and some jacks. Preamp current draw is only <30mA with the vactrols. For my pedal I used DC-DC converter (9-36v -> 24v) and now it powers even 9v battery, wall wart being a better option of course.

I designed a pcb and used parts that fit Hammond 1590B enclosure, so no wiring needed. Only expensive parts on the VV preamp (besides vactrols) are the pots, so for this pedal I used single pots instead of dual concentric ones. It needs C50k for depth control (can be modded with b100k&100k res) but for speed control I left out the 82k res for the "slow speed switch" and used b100k instead. So, this pedal has larger scale, which I liked more.

That's basically it. I'll not be sharing gerbers but I can sell pcb for personal use. This as a courtesy towards VV, they do excellent work and I don't want to harm their business. PM if interested.

Cheers,
Janne

92

Parts, Service, Maintenance & Repairs / Re: Is my Rhodes beyond repair?

« Last post by sean on September 12, 2019, 06:17:36 PM »

Real shame that the previous owner reduced it to kit form.

Don't vacuum up any of the tiny white felts and paper shims around the balance rail pins.  Yes, you will probably have to buy at least some new felts and shims.  See https://www.vintagevibe.com/products/balance-rail-felts and https://www.vintagevibe.com/products/key-shims or
https://www.vandaking.com/s-332a-balance-rail-punchings.html

I usually scrub the wood with a toothbrush while I vacuum, and hold the felts and shims down with my fingers when I get close to them.  You have to really concentrate to avoid accidentally sucking them up.  I have had to fish them out of the vacuum canister on occasion.

Those ugly green felts around the front guide pins are particularly useless.  I would just vacuum them up while cleaning it.  Later model pianos just had a long strip of felt glued along the row of guide pins.  The keys themselves never touch these felts anyway (unless you raise the hammer with your finger during maintenance and cleaning).  You can buy replacement felts https://www.vintagevibe.com/products/front-rail-felts or https://www.vandaking.com/s-331-front-rail-punchings.html.

Oh wow!  It has half-wood hammers and square hammer tips!!!  What year is it?  1973 maybe?  What do the date stamps on the far right of the harp look like (on the wood near the serial number plate)?  Wait!  The keys don't look like they are from a 1973 piano.   It has wooden harp supports, and the fender logo on the name rail, so maybe it is 1974.  The case has the old-style small hinges.  Hmmm...  what date?

Why is the key frame loose?  It should be screwed down tight to the case.  Ugh.  I hope you can figure out which screws go where.

Anyway, after you do a minor cleanup, I would put the piano together as best you can before you buy any parts.  Then you can start deep-cleaning and working on it section by section. 

You might not want to buy the VV refurb kit if you decide to keep the square hammer tips.  (I personally love half-wood hammers with square hammer tips.)

When you get the piano looking like a Rhodes again, you can certainly discuss with Chris or Fred at Vintage Vibe what parts and hammer tips you should get.

Sean

93

Preamps, Modifications & Upgrades / Re: DIY Peterson preamp (tremolo) pedal

« Last post by sean on September 12, 2019, 05:31:26 PM »

Janne,

18 seconds?  Really?  18 SECONDS!??  That's all you are giving us?

This looks wonderful!  Awesome job.  Did you make only one? 

Can you share the Gerber files for the PCB?

Can you tell us what model Vactrol you used, and where you bought it?

This is really awesome, so we want to hear a whole lot more about the whole project.

Sean

94

The Wurlitzer Electric Piano / Re: Wurlitzer 700 help

« Last post by pianotuner steveo on September 12, 2019, 06:14:07 AM »

I'm pretty sure that some were made without those wood spacers, I've seen a few without them.
It is possible that they are turned sideways like Doc mentioned, be sure that the long side is up/down.

95

Parts, Service, Maintenance & Repairs / Re: Passive Electronics

« Last post by Alan Lenhoff on September 11, 2019, 03:46:06 PM »

Keep that excitement going! Some comments:

The "bass boost" knob is actually a bass cut control.  So, at it's maximum setting, you won't hear any more bass than what you'd get taking a signal directly from the harp. Given that, is it possible it's working properly?

Maybe try cleaning the volume pot before replacing it?

When you replace the grommets, replace the screws, too.  Nice straight screws are important in allowing you to get everything aligned correctly.

If you decide to save some or all of your tonebar springs, be aware that different springs are used in different regions of the piano, so don't get them mixed up.

The really tight bass springs probably resulted from someone trying to reduce the escapement in that area (the distance from the hammer tip with the key depressed and the bottom of the tine).  Setting the escapement should be on your list -- a critical part of being able to play the piano with both a light and hard touch.  The Rhodes service manual (and the archives of this group) offer good suggestions for how you can get this right  for your style of playing. Generally, you'll do this by adjusting the number of shims on the bass and treble harp supports.  (Although sometimes that's not enough.) The three Rhodes pianos I've owned all came with the escapement set too high from the factory. Removing some shims made the pianos much easier to play softly.

And speaking of the service manual, if you haven't given it a good read, this would be a great time to do so.

One more hint:  Don't replace parts without having a good reason to do so. It's not just a question of saving money: The replacement parts available today are of varying quality. You can lose some of the original character of the piano by needlessly substituting modern parts.

Good luck!

Alan

96

Parts, Service, Maintenance & Repairs / Passive Electronics

« Last post by Dr. Monster on September 11, 2019, 02:55:03 PM »

Hi all!

I just purchased my first Rhodes piano and I am extremely excited, but it needs some work. I have a few questions:

The passive electronics are not working correctly. The bass boost knob does nothing, and the volume knob only “works” past about 3 ‘O clock. Before this, there is no signal, then a bit of static. At 3 ‘O clock it pops into working at 100% volume and sounds identical to plugging directly into the harp with a 1/4” RCA adapter. I’ve seen the post detailing the original wiring diagram here: https://ep-forum.com/smf/index.php?topic=4650.msg22605#msg22605 . Everything looks wired correctly on mine.

Are there any good ways to troubleshoot this problem with the existing passive electronics on my piano, or should I look into replacing the pots/cap entirely? Should I buy a new RCA cable somewhere? I’d love suggestions on parts sourcing if this is a good way to go.

If I decide to replace the pots, what are some options other than the original specs? I saw a post from user “pnoboy” that said “Fender chose to use a 10k pot for the volume control, which does remove some of the sparkle from the sound.  A nice change can be made by changing the volume pot to a 50k audio taper, the bass pot to a 250k reverse-audio taper, and the capacitor to 10 nF”


I’ve attached a picture of the Harp. It looks like the worn out grommets should be replaced. Some of the springs look rusted/broken as well as screwed in extremely tight at the bottom end. should I replace those too?

Thanks!

My overall restoration plan is as follows:

1. Replace grommets/springs
2. Clean interior of case, polish tines, tone bars, etc.
3. Replace passive electronics
4. Diagnose strike line, key leveling/dipping
5. Tune & voice as needed
6. Re-Tolex or paint exterior

Let me know if there is anything else I should be thinking about!

97

Preamps, Modifications & Upgrades / Re: Rhodes Peterson preamp powering

« Last post by JanneI on September 11, 2019, 09:51:45 AM »

Mean Well RS-15-24 is the one inside the Vintage Vibe power (red color). It's easy to throw inside a hammond enclosure. Find that 4 -pin DIN female connector and wire two 1/4" jacks and you'll have the same box.

BTW. The vactrol version of this peterson preamp (VV preamp) has <30mA current draw.

98

Preamps, Modifications & Upgrades / DIY Peterson preamp (tremolo) pedal

« Last post by JanneI on September 11, 2019, 01:06:57 AM »

Hi,

I made a DIY peterson preamp pedal. It uses vactrols (like VV preamp), otherwise it's identical with original Peterson. Here's a quick demo which compares it to VV model:

https://youtu.be/d2y6bqWHQtU

Best,
Janne

99

Amps, Effects & Recording Techniques / Re: Peterson stereo pan pedal?

« Last post by JanneI on September 11, 2019, 01:02:02 AM »

https://youtu.be/d2y6bqWHQtU

Here's my diy project demo.

100

Other Keyboards & Software Synths / Re: Cembalet N Squealing Noise

« Last post by OZDOC on September 10, 2019, 07:44:56 PM »

My Cembalet restoration got put on hold while Alan and I completed the book on vintage keyboards we were writing - see Classic Keys, Lenhoff & Robertson on Amazon Books.
There are a few photos of my earliest Cembalet in that. But, with your experience in mind I think I'll set aside the felt dampers that I was going to fit to it, and find a suitable foam extrusion. There is no doubt that the felt has the ability to retain charge - which is always a point of concern with capacitive pick-up systems.