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Messages - pnoboy

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61
Glad you've got some good electrolytic caps in there. Definitely worth having on an amp of this vintage.

Love playing the Rhodes through the tremolo effect on this amp. How are you finding the quality of the tremolo? If you play a sustained bass note with the tremolo intensity cranked, do you hear a slight chopping or ticking sound?

The Rolas aren't bad but you might get a wider more Rhodes friendly range with a pair of JBLs or EVs in the Twin.

Yeah, but then you'll need a forklift to move your Twin Reverb around!  LOL

62
OTOH, the Peterson, Janus, stage, and late Mark II pianos all had input impedances way below 1 Meg, and I don't recall them being noisy.  That's certainly true for the stage piano.

63
I play my '75 MKI Rhodes through a couple effects...Boss TR-2 Tremolo, Small Stone, etc. for that kind of goodness.

Since the Rhodes is quiet and pretty dark naturally, I also use a Tech21 Liverpool as a preamp to bring the signal up and introduce some top end sparkle. The only problem is when I boost the signal I get hiss.

Does anyone run a Noise Suppressor with your other effects to quiet your Rhodes?

I wonder if the problem is the Tech21 preamp.  I run my Rhodes with plenty of high end and don't get hiss.  BTW, I assume you run the signal through the Tech21 before the other pedals?

64
If you like the sound of your harp plugged directly into your electronic chain, you may well not like the sound of the Janus amp or the standard stage-piano schematic.  Both have input impedances of 10k, which will definitely make the piano sound duller, with less of the hammer-impact sound.  The stage-piano circuit can be mostly cured of that problem by scaling the components.  For example use a 50k audio-taper pot for the volume control, a 250k reverse audio-taper pot for the bass control, and a 0.01 uF capacitor.  To my thinking, the Janus preamp is pretty much a waste of money.  I'd put in the stage piano circuit using the values I mentioned, and then make a front panel to cover the unused holes.  Another benefit of doing that is that you won't have to run power to the piano, which is a PITA.

65
Preamps, Modifications & Upgrades / A different sort of preamp
« on: April 08, 2018, 10:52:31 AM »
I’ve been a fan of the stage piano for a long time, having owned both a suitcase piano and 2 stage pianos.  I think that Fender made some unfortunate choices in the suitcase amp that caused it to be much heavier than it needed to be as well as to have a tone quality that was not to my liking.  The great advantage of the stage piano are the wide variety of amps and speakers that are available, allowing a much greater range of tone, volume range and size.   

Because of the variety of available amps and pedals, I’ve been a bit surprised at how much interest there is in preamps for the stage piano.   Why build a special preamp that may require irreversible modifications to one’s piano when one can pick an amp and pedal to get the desired tone?

The Dyno-My-Piano preamp is a good example.  It creates a large hole in the frequency response centered around 500Hz.  That’s fine if you like that sound, but for less money and fuss, one can by an equalizer that can not only create that tone quality, but many others as well.  Tube preamps also seem to enjoy some cache.  But, why not just buy a tube amplifier if one finds tubes to be advantageous?

People often think the soft clipping provided by tubes will be a boon to the Rhodes’ sound, but that idea is largely a siren song.  If one is playing moderate to complex chords, any audible distortion will sound really awful.  If one wants to play single-note leads and power chords like guitarists do when using distortion, then full-blown distortion such as provided by distortion pedals will work well.  Also, tubes, specifically triodes, provide soft clipping over a relatively narrow range of volume that doesn’t work well if one is playing using both single notes and chords together.

After thinking about all of us, I decided that there was one type of preamp that would make sense.  The output of the Rhodes harp is pretty low—lower than most guitars.  Also, the sound of the harp changes when loaded by the control in the stage piano.  So, I thought if one could design a preamp that would deal with these issues, and, at the same time, require no modifications to the piano and no external power supply, it would be worthwhile.  So, that’s what I did.

My preamp is very small and mounts by its ¼” phone jack, using the preexisting hole in the name rail.  A phono input jack connects between the harp and the preamp, and the output of the preamp connects to a 2nd phono jack using the preexisting phone plug for the piano’s name rail. The preamp is turned off unless a guitar cord is plugged into the piano.  Given the preamp’s tiny load current, a 9-volt battery will last more than 400 hours—that’s a lot of playing..  So, if you play your piano 10 hours a week, the battery will last at least 40 weeks—pretty close to a year.   If the preamp or its battery should fail, in about 2 minutes one can unplug the preamp from the harp, and plug the front-panel controls back into the harp.  Here are the specs, which were derived from direct measurements or SPICE simulation.  BTW, the preamp is a totally discrete design, with no ICs.  With its high impedance, and the short cord between the harp and preamp, none of the harp’s signal is lost or suppressed.

All specs were measured with a 2V P-P input signal and an output load of 10 kohms
Distortion              approx. 0.25%, largely 2nd harmonic
Input impedance   2 megohm
Output impedance   500 ohms—set by series resistor
Freq response      6 Hz to 110 kHz 3db down, flat in between
Max input              3 V P-P
Slew rate              0.3 v/usec
Gain                    5.5 dB
Output noise      2.8 uV (50 Hz to 10 kHz)
Power supply      9V battery
Current drain      1 mA

This 1st pic shows the preamp itself.  If I relayed it out, I could make it much smaller—I purposely left lots of room between the components for this initial trial in case I needed to make some modifications.

The 2nd pic shows how the preamp is mounted on the name rail.  The ¼ phone jack is removed, and the preamp installed in its place.  The green and yellow wires were previously soldered to the removed phone jack.  The little battery box is attached to the name rail by double-stick foam tape.  This stuff holds ferociously, but can be easily removed by slicing through the foam with a single-edge razor blade.

The final pic shows what the installation looks like with the name rail in place.

66
A Dremel cut off would work fine--a little heat right at the tip wouldn't affect the oscillation, which is mostly controlled by the portion of the tine that is closest to its mounting block.  If you wanted to be extra careful, you could wrap a damp paper towel around the tine, exposing just the portion where you want to cut.  Alternatively, you can use nippers, and then, if necessary, use the Dremel to clean up the cut.

67
I took of the shims on my piano.  They're glued quite tightly.  I used a wood chisel to get most of the wood off, and then mineral spirits and/or acetone to soften the glue, and then applied a putty knife to scrape off the softened glue.  It was a bit of a job, but it turned out well.

68
Use an ohmmeter to check for continuity.  At some point, you should encounter a break.  There's also a possibility of a short somewhere.

69
I assume you're referring to the spring pin that Fender used for the pivot.  You should be able to push the remaining part of it out of the moveable part of the pedal assembly.  It'll have to come out at some point.

70
Actually, the suitcase preamps didn't have 1 megohm input impedance.  The Peterson preamp had a 33k input impedance--
http://www.fenderrhodes.com/org/ch11/fig11-8.jpg
The Janus preamps had a 10k input impedance--
http://www.fenderrhodes.com/org/ch11/fig11-1.jpg
The late Mark II preamps had 46.4k input impedance--
http://www.fenderrhodes.com/pdf/late-mark2-suitcase.pdf

71
Thanks for your testing, Sean.  I would like to make a quick comment about the standard stage controls that I discussed and you tested.  There is a noticeable change in tone and volume if one is using the 10k volume pot that came with the pianos or if the component values are scaled to use 50k or higher volume pot.  In the latter case, the volume is higher and the tone brighter., with more of the hammer-strike sound.

72
OK--I was just trying to figure out why you were experiencing noise, and was grasping at straws to come up with some ideas.  BTW, last night I repeated my noise test to be sure I had remembered it correctly.  I turned my amp way up, stuck my ear right next to the speaker, and listened for a difference in noise between having my piano plugged in and having nothing plugged in.  In the latter case, the shorting jack shorted the amp's input.  Once again, I could barely hear the difference. 

73
Jenzz, G'day there...
The Rhodes was completely restored by CEPCo 10 months ago...  no issues from that perspective.
The noise I speak of is the standard noise you get from single coil pickups. The Rhodes, last time I looked, had quite a few single coil PUPs.

I am still trying to come to grips with the concept that a Rhodes needs (or needed) a bass boost.  Every amp I have ever used, or player I know who plays a Rhodes, have always had to reduce the bass via the amp controls.

FYI, with the circuit that was in my Rhodes, as the Bass Boost was rolled off  (ie the level of bass relative to the treble reduced) the overall volume of the treble decreased as well.  I measured this with a signal generator. That circuit, 10k/10k/0.1uF, is a dud circuit.  Even the 50k/10k/0.047 version circuit would have been better.  I even built up a copy of the 10k/10k/0.1uF circuit with brand new components and the results were the same.

Irrespective of the above ...  the Rhodes I have was manufactured with a crappy designed volume/tone control which was useful at basically one combination of the volume/tone controls.  I have looked at the issue from the way I would if I was designing an amp/guitar combo and come up with a circuit that is useful at the entire range of positions.

the Rhodes sounds awesome ... even better than it did.
And people can use the circuit if they wish or ignore it ...  that's what forums like this are for.

David

Which tone control did your Rhodes originally have?  The older one that you showed in a hand-drawn schematic, or the newer one that I commented on?  If it was the older one, then, yes, the circuit was worse than worthless.  Re noise, an impedance mismatch does not cause noise per se.  For example, your new circuit uses a 1 meg pot, but the output impedance of the Rhodes harp is much, much lower than that.  One can say the same of guitars--the impedance of a guitar pickup is a few k ohms, but guitar volume controls and amps have a much higher impedance.  For an audio amp, an impedance mismatch is often good--and usually the input impedance of an audio amp is purposely made  to be much higher than the output impedance of what is connected to it.  I'd have to do a noise analysis to show this, which is well beyond what I'm willing to do for this forum.  I am still confused by the noise you report.  You have pictures of your Rhodes with your preamp sitting right on top of it.  Have you tried moving your preamp away from the Rhodes to see if that alters the noise?  I have owned 3 Rhodes--1 suitcase piano, and 2 stage pianos.  All are/were very quiet.   I really couldn't tell when they were plugged into an amp.  I can plug my current Rhodes into my amp and listen, then unplug it, and I don't hear any difference unless I put my ear right near the speaker.   Remember, that the Rhodes' single-coil pickups are connected in reverse polarity in groups of 3.  So, collectively, they really function as a sort of large, distributed, humbucker design

74
I'm going to express a contrarian viewpoint, and I hope I can do so respectfully.  The OP presented 2 Fender stage-piano schematics--one hand drawn and one printed.  The printed one represents what Fender used for most of the life of the stage piano, and, except for the component values, I think that it is quite a good circuit, and better than the one designed by the OP.  Before I explain my opinion, let me mention my experience with my Rhodes stage pianos.  I have owned 2--the second of which I currently own.  In both cases, I found that the pianos could sound tubby if not properly equalized, and the tubbiness originated in the 100 Hz to 200 Hz frequency range.  Lower down the bass end of the piano, less equalization was required.  I think this results largely from the fact that most guitar speakers severely roll off bass as one goes below 80 to 100 Hz. 

Therefore, my experience was that a bit of a reduction in the 100-200 Hz range without too much reduction further down in the bass was just the ticket for good sound.  Of course, the amps, speakers, and speaker cabinet have lots to do with the sound of the piano, so my experience can't be considered universal.  I gigged with the 1st piano, and played it through 2 12" speakers in an open-back cabinet.  I think that speaker arrangement is pretty typical for many Rhodes players.

The Fender tone control provides what is often called a shelving high-pass filter.  The capacitor and volume-control resistance makes the high pass, and the resistor across the capacitor creates the shelf.  BTW, Fender calls this control a “bass boost,” but that’s just some marketing nonsense—it’s actually a bass-cut control.  In fact, it's kind of a 1/2 bass control.  Whereas most bass controls go from cut at one extreme, to flat in the middle, to boost at the other extreme, the Fender control goes from cut at one extreme to flat at the other.  Consider the image below .  It shows the frequency response with the bass control set for full cut and partial cut.  At the partial cut shown, it reaches a shelf of -6dB, where it flattens out.  At full cut, it's heading for a shelf, but doesn't quite get there at 20 Hz.
I find this type of control very useful.  It can cut the mid to upper bass frequencies without completely suppressing the lowest frequencies.  The OP's circuit cannot do this--as a simple high-pass filter its, bass rolloff never stops.  I have found that I never need that type of frequency shaping with my Rhodes pianos. 

As to the selection of component values.  It seems that Fender likes to suppress the sound of the hammers hitting the tines--I think of it as a ping or ting.  I say this, because, in general, Fender has used low input impedances in their pianos.  The Peterson preamp has a 33k input impedance, the stage pianos has a 10k input impedance, the early Janus preamps have a 10k impedance, whereas the late MkII preamps had a 47k impedance.  If one wants a higher impedance to let through more of the ping, the components used in the Fender schematic can be scaled as long as the RC product remains the same.  For example, one can multiple the potentiometer values by 10 and divide the capacitor's value by 10--hence, a 100k volume pot, and 500k tone post, and a 4.7nF capacitor.
The OP also mentions static or hiss.  I have never encountered this with my stage pianos--they have all been very quiet.  I wonder if the OP's problem relates more to his amp than piano?  The 10k pot does reduce amplitude, but if increased to 50k or more, that problem is resolved.  In short, I have no real criticisms of the Fender circuit--it does what the manufacturer wanted it to do in an efficient way.  In that sense, I think it's rather an elegant design.  If you want more ting in your sound, scale the pots up and the capacitor down. 

75
I have to say that I agree with Tim from Retrolinear.  I think there would surely be broad agreement that hiss and hum are not desirable.  Would anyone want a stereo system with hum and hiss?  The most likely situation is that players of the Wurli put up with the hiss and hum because they didn't know how to get rid of it.  I suspect 99% of Wurli players would be happy to get rid of both it it was free and simple to do.   As for other aspects of the amp, as Tim stated, if you duplicate the input impedance, the gain and frequency response of the whole amp as measured with its speakers connected (some amps behave differently when connected to a complex load as compared to a resistive load), its power output, and its distortion characteristics, then your amp will sound the same as the Wurli amp.  Distortion is often misunderstood--it you can't hear it, it's of no consequence, and in general, I don't think Wurlis had or were played with noticeable distortion.  I had a Wurli once, and played it through a guitar amp to get enough volume for gigging.  Clearly, this amp had different characteristics than the built-in amp, but in no way did I feel that it detracted from the Wurli sound.

I am reminded of a story that a former colleague of mine told me.  He used to work at the Zildjian cymbal company, which would allow some musicians to come in and select the cymbals they liked the best.  Often a musician would go through all the cymbals of a given type looking for the best one.  If they didn't find one out of their stock, the company would start giving the musician the same ones they had previously tried.  Often, the musician would find the "best" one and leave a happy camper.
Again affirming the consequent, if not appeal to complexity, moving the goalposts. Fallacious arguments.
Fallacious in your opinion.  If I affirm the consequent, so do you with your unsubstantiated claims.  Also, I didn't move the goalposts, I merely asserted that one can ascertain the behavior of an audio amplifier by measuring the appropriate parameters.

As previously explained it was because digital has spoiled the ear to pick out noise immediately. Already explained inherent noise in pipe organs, leakage in Hammond organs, for some reason is being missed in the information uptake. Yet for generations, noise in everything electronic audio was accepted and overlooked. Records with pops and clicks.
Not true--noise was not accepted and overlooked in the pre-digital era.  Audio amplifiers and receivers often came with pop and click filters to reduce the undesirable sounds of scratched and/or dirty records.  Amp designers went to great lengths to minimize hiss and hum, and the reviews of audio products typically measured and published the value of hiss and hum of reviewed products.

And still long playing records have a sound that digital has not duplicated yet. We have left behind a fuller sounding medium for no noise and ease of cartage and fooled one's self that things are as best as they can be.

Many would disagree with you.  Although some listeners say that CDs have audible flaws, there are other digital reproduction standards that outdo CD quality such as SACD and DVD audio.  I believe the best digital reproduction can withstand double-blind testing.  You do believe double-blind testing, don't you?

The issue I have with changing the amps/preamps in a Wurli is the way the keyboard sounds react. I have not heard a mod that retains the basic character and reaction to the player of the piano, (with or without the noise). It is similar to how some guitar pedals will adversely affect the sound of a guitar and a hunt for something else or a mod is done as the player does not like the way his guitar now reacts with certain pedals in the chain.
This is simply asserted by you without proof.  Further, unless tested in a double-blind way, your statements carry little weight.  You say you have "not heard a mod that retains the basic character and reaction to the player..."  That is a phenomenally broad statement that hardly seems believable.  Either you have only heard poorly designed mods, or your conclusions are likely prejudiced by your expectations.  Psycho-acoustic testing and decades of audio testing have shown that humans are incredibly suggestible.

The cymbal story only proves one thing, that in any situation, the best of the lot presented will be chosen.
Quote
Perhaps I didn't adequately describe the situation.  After the musician tried all the examples of a particular cymbal, he was not told that he would then try the same ones to pick the best, or, perhaps, the least bad of the lot.  Instead, he was presented with the same cymbals without being told that he already tried them.  Often, he would find one of the cymbals he previously rejected and now thought was just what he wanted.

Some can't tell that the sound/reaction has changed (to the player) and it won't matter to them.
..but you, with your superior hearing can tell, no doubt?

As mentioned, working production for a named touring band supplying them with a Wurli just last Saturday, they merely asked for a backup Wurli at the ready, having brought their own "modded" 200A with tremolo speed knob. Someone we know of must've been the one who worked on that Wurli but here you have the band wanting a backup nonetheless.

So much for "reliability."

You have no specific information as to the reliability of Tim W.'s circuit.  It may be 10x the reliability of the original.  I surely don't know, and neither do you.

Everything audio has been based on a signal to noise ratio. But if like the guitar player the Wurli player does not like when he strikes the keys and the sound does not react the way he's experienced before, he will not be satisfied and will want to move on.
This is surely not the case.  SNR is one of the many important parameters of audio equipment, but hardly the only one that audio designers have paid attention to and have striven to optimize.

Even shielding a guitar for example changes the sound of that guitar's pickups. You'll either like it or not. But to say "it has less noise" as the only indicator of improvement is a weak reason to change things.
If that's true, then the shielding changed some other parameter(s) that are probably not that hard to measure.  Sound reproduction is not magic.

More fallacious arguments, strawman, resorting to AD HOMINEM. Geeze...

i THINK YOU NEED A CRASH COURSE IN LEARNING HOW TO COMMUNICATE.

You take a sentence, change the intent and then substitute something else as if that was the original intention.

Nothing you said made sense as regards what I said.

Learn the difference rather than put words in people's mouths.

AD HOMINEM!

Look it up!
You say, "You take a sentence, change the intent and then substitute something else as if that was the original intention."  All I did was quote you word for word--nothing added, nothing deleted.  Additionally, I showed your whole post, so the context of your statements would be clear.  You then go on to accuse me of ad hominem, whose meaning I don't have to look up, when the folllowing are the things you said about me,

"i THINK YOU NEED A CRASH COURSE IN LEARNING HOW TO COMMUNICATE.

You take a sentence, change the intent and then substitute something else as if that was the original intention.

Nothing you said made sense as regards what I said.

Learn the difference rather than put words in people's mouths."

Those are quite a string of insults!
  None of them are true, IMO.  I am happy to let other readers of this post draw their own conclusions about my ability to communicate and the content of my posts.  In any case, I am calling a truce--there's nothing more I need to add, and I will graciously allow you the final word if you so choose.

76
I have to say that I agree with Tim from Retrolinear.  I think there would surely be broad agreement that hiss and hum are not desirable.  Would anyone want a stereo system with hum and hiss?  The most likely situation is that players of the Wurli put up with the hiss and hum because they didn't know how to get rid of it.  I suspect 99% of Wurli players would be happy to get rid of both it it was free and simple to do.   As for other aspects of the amp, as Tim stated, if you duplicate the input impedance, the gain and frequency response of the whole amp as measured with its speakers connected (some amps behave differently when connected to a complex load as compared to a resistive load), its power output, and its distortion characteristics, then your amp will sound the same as the Wurli amp.  Distortion is often misunderstood--it you can't hear it, it's of no consequence, and in general, I don't think Wurlis had or were played with noticeable distortion.  I had a Wurli once, and played it through a guitar amp to get enough volume for gigging.  Clearly, this amp had different characteristics than the built-in amp, but in no way did I feel that it detracted from the Wurli sound.

I am reminded of a story that a former colleague of mine told me.  He used to work at the Zildjian cymbal company, which would allow some musicians to come in and select the cymbals they liked the best.  Often a musician would go through all the cymbals of a given type looking for the best one.  If they didn't find one out of their stock, the company would start giving the musician the same ones they had previously tried.  Often, the musician would find the "best" one and leave a happy camper.
Again affirming the consequent, if not appeal to complexity, moving the goalposts. Fallacious arguments.
Fallacious in your opinion.  If I affirm the consequent, so do you with your unsubstantiated claims.  Also, I didn't move the goalposts, I merely asserted that one can ascertain the behavior of an audio amplifier by measuring the appropriate parameters.

As previously explained it was because digital has spoiled the ear to pick out noise immediately. Already explained inherent noise in pipe organs, leakage in Hammond organs, for some reason is being missed in the information uptake. Yet for generations, noise in everything electronic audio was accepted and overlooked. Records with pops and clicks.
Not true--noise was not accepted and overlooked in the pre-digital era.  Audio amplifiers and receivers often came with pop and click filters to reduce the undesirable sounds of scratched and/or dirty records.  Amp designers went to great lengths to minimize hiss and hum, and the reviews of audio products typically measured and published the value of hiss and hum of reviewed products.

And still long playing records have a sound that digital has not duplicated yet. We have left behind a fuller sounding medium for no noise and ease of cartage and fooled one's self that things are as best as they can be.

Many would disagree with you.  Although some listeners say that CDs have audible flaws, there are other digital reproduction standards that outdo CD quality such as SACD and DVD audio.  I believe the best digital reproduction can withstand double-blind testing.  You do believe double-blind testing, don't you?

The issue I have with changing the amps/preamps in a Wurli is the way the keyboard sounds react. I have not heard a mod that retains the basic character and reaction to the player of the piano, (with or without the noise). It is similar to how some guitar pedals will adversely affect the sound of a guitar and a hunt for something else or a mod is done as the player does not like the way his guitar now reacts with certain pedals in the chain.
This is simply asserted by you without proof.  Further, unless tested in a double-blind way, your statements carry little weight.  You say you have "not heard a mod that retains the basic character and reaction to the player..."  That is a phenomenally broad statement that hardly seems believable.  Either you have only heard poorly designed mods, or your conclusions are likely prejudiced by your expectations.  Psycho-acoustic testing and decades of audio testing have shown that humans are incredibly suggestible.

The cymbal story only proves one thing, that in any situation, the best of the lot presented will be chosen.
Quote
Perhaps I didn't adequately describe the situation.  After the musician tried all the examples of a particular cymbal, he was not told that he would then try the same ones to pick the best, or, perhaps, the least bad of the lot.  Instead, he was presented with the same cymbals without being told that he already tried them.  Often, he would find one of the cymbals he previously rejected and now thought was just what he wanted.

Some can't tell that the sound/reaction has changed (to the player) and it won't matter to them.
..but you, with your superior hearing can tell, no doubt?

As mentioned, working production for a named touring band supplying them with a Wurli just last Saturday, they merely asked for a backup Wurli at the ready, having brought their own "modded" 200A with tremolo speed knob. Someone we know of must've been the one who worked on that Wurli but here you have the band wanting a backup nonetheless.

So much for "reliability."

You have no specific information as to the reliability of Tim W.'s circuit.  It may be 10x the reliability of the original.  I surely don't know, and neither do you.

Everything audio has been based on a signal to noise ratio. But if like the guitar player the Wurli player does not like when he strikes the keys and the sound does not react the way he's experienced before, he will not be satisfied and will want to move on.
This is surely not the case.  SNR is one of the many important parameters of audio equipment, but hardly the only one that audio designers have paid attention to and have striven to optimize.

Even shielding a guitar for example changes the sound of that guitar's pickups. You'll either like it or not. But to say "it has less noise" as the only indicator of improvement is a weak reason to change things.
If that's true, then the shielding changed some other parameter(s) that are probably not that hard to measure.  Sound reproduction is not magic.


77
I have to say that I agree with Tim from Retrolinear.  I think there would surely be broad agreement that hiss and hum are not desirable.  Would anyone want a stereo system with hum and hiss?  The most likely situation is that players of the Wurli put up with the hiss and hum because they didn't know how to get rid of it.  I suspect 99% of Wurli players would be happy to get rid of both it it was free and simple to do.   As for other aspects of the amp, as Tim stated, if you duplicate the input impedance, the gain and frequency response of the whole amp as measured with its speakers connected (some amps behave differently when connected to a complex load as compared to a resistive load), its power output, and its distortion characteristics, then your amp will sound the same as the Wurli amp.  Distortion is often misunderstood--it you can't hear it, it's of no consequence, and in general, I don't think Wurlis had or were played with noticeable distortion.  I had a Wurli once, and played it through a guitar amp to get enough volume for gigging.  Clearly, this amp had different characteristics than the built-in amp, but in no way did I feel that it detracted from the Wurli sound.

I am reminded of a story that a former colleague of mine told me.  He used to work at the Zildjian cymbal company, which would allow some musicians to come in and select the cymbals they liked the best.  Often a musician would go through all the cymbals of a given type looking for the best one.  If they didn't find one out of their stock, the company would start giving the musician the same ones they had previously tried.  Often, the musician would find the "best" one and leave a happy camper.

78
Changing parts on anything will change the sound.

One has to decide whether changing the original character of a preamp or amp, even the speakers, the circuit constants (how long the original wires were and their gauges) is something one wants.

A trade-off is losing that "sound" when going after hum and/or upgrading a Wurli for one reason or another.

There is a software called Broken Wurli  by Soniccouture that has sampled a Wurli sound featuring the faults of Wurlis as a positive recording tool including the distortion and the buzzing with a modeled noise output.



That said, would like to hear a clip of the Illdigger mods.

I would say that the mods discussed don't change the sound, but improve the sound.  Do you think that hiss and hum are good things?

79
Preamps, Modifications & Upgrades / Re: Miracle Mod Issue
« on: February 15, 2018, 12:31:24 PM »
You need only a small piece of wood, and by comparison to the weight and moment of inertia of the hammer, the latter of which is multiplied by the square of the action ratio between the key and hammer, you will absolutely not notice any effect from the extra piece of wood.  I think almost any type of wood would be fine, but I'd probably use something harder than pine so that it wouldn't get damaged during future maintenance, such as replacing the pedestal felts. 

80
Preamps, Modifications & Upgrades / Re: Rhodes Preamp Bypass
« on: February 15, 2018, 12:26:16 PM »

I don't believe you are splitting atoms.  You are inventing unicorn leprachaun atoms.

The RCA connector has been providing hi-fidelity audio connections for more than seventy years.


In situations where you don't have to worry about a cable getting yanked out, or needing strain relief, or care that the hot gets connected before the ground, or are not too picky about corrosion resistance, a plain-old RCA jack is great.  Most folks that take their signal straight from the harp still use the factory-original RCA jack.  Some folks get fancy and pay for a gold-plated RCA jack.  Some folks mount a 1/4" jack on the harp.  None of these are going to change your quality of life in any significant way.

However, the reason that some people choose to take their signal direct from the harp (and avoid the bass boost and volume pot on the name rail) is because their choice of amplifier (or preamplifier) doesn't perform well with the Rhodes 10KΩ volume pot across the input.

Many of the old-fashioned tube amps have high-value resistors across the inputs before the first tube.

e.g., the Fender Twin circuit (schematic URL AWOL) shows that if you plug your Rhodes into Jack 1, the first component it hits is R1 - a 1-MegΩ resistor.  If we plug our stage Rhodes into this jack, then we have put the 10KΩ volume control in parallel with this 1-MegΩ resistor.  Even if we have the volume set to max on the namerail, this 10KΩ in parallel with the 1-MegΩ resistor brings the combined value down to 9,901 Ohms.  This greatly reduces the (already low) signal strength of the Rhodes before it hits the first tube.

This is the reason for the notorious tone suckage of the Stage Rhodes into some tube amps.  This is also the reason that bypassing the namerail circuitry fixes the problem.  If you come straight off the RCA jack at the back left of the Rhodes harp, then you have no 10K Ohm potentiometer to be in parallel with the input resistor on the amp.

Sean


I will have to find the online fender schematics and update the old post at https://ep-forum.com/smf/index.php?topic=6868.msg34468#msg34468

A 1meg input impedance does not suck tone or volume.  The effect of the 1meg input resistor is miniscule by comparison to the 10k resistor of the stage piano's volume control--a 1 meg resistor is 100 times bigger than a 10k.  It's the 10k volume-control pot that is the source of the volume loss and tone change--the input impedance of almost any guitar amp is much higher than 10k and will not affect the tone and/or volume of the piano.

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Ben,  have you tried a range of digital reverb pedals?  It's hard for me to believe that there's not at least one out there that would sound good with a Rhodes.  Actually, I have not found reverb to add much to the Rhodes sound anyway.  Reverb sounds great with guitar,  because guitars have quite a short sustain, and as the note decays you can hear the "air" that the reverb adds.  However, a Rhodes has such a long sustain that you hardly hear the reverb--at least that's been my experience.

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Preamps, Modifications & Upgrades / Re: Rhodes Preamp Bypass
« on: February 11, 2018, 06:12:07 PM »
I wouldn't be hard, but if you send the signal to a volume pedal, it would need to have a buffered input, or you'll run into the same problem.  I think all you have to do is to remove the ground wire from the volume pot, and turn the volume and bass knobs all the way up.  The rest of the wiring can remain in place, and you can undo your mod very easily.

83
Preamps, Modifications & Upgrades / Re: Miracle Mod Issue
« on: February 11, 2018, 06:08:29 PM »
I think the best bet would be to glue a relatively thin strip of wood on the pedestals that don't stick far enough forward.  Do you have access to a table saw or a router table?  If you do, it should be a pretty quick fix.  The strips wouldn't even have to run all the way down to the keystick.  Just make sure the grain orientation matches that of the pedestals.

84
The Fender Rhodes Electric Piano / Re: Low volume and hiss on my MK 1 Stage
« on: February 09, 2018, 04:51:03 PM »
There's got to be something wrong.  The Rhodes puts out plenty of volume to make any guitar amp sound fine.  Can you borrow another amp from a friend to connect to your Rhodes?  If that test also shows a problem, then you definitely have to trouble shoot your piano.

85
I used to use a phasor, but it sounds so 70s, and I really don't like it any more.  A bit a tremolo can sound nice.  I tried a true vibrato pedal , but somehow vibrato sounds much better on a Hammond than a Rhodes IMO.  Most of the time I just try to get the best natural Rhodes sound I possibly can.  To some extent, that's a never ending quest, but I'm making progress.  Next, I'm going to try a buffer/boost circuit of my own design that mounts in the piano, under the hood.  If it works well, I'll post some info on it.

86
The Fender Rhodes Electric Piano / Re: Customize or bone stock
« on: February 08, 2018, 11:41:16 AM »
There are some unhelpful notions about speaker baffles that have been expressed.  First, baffles are not supposed to resonate--they're supposed to be stiff and acoustically dead.  A resonating baffle causes uneven loudness of some notes, and often either tubby or nasal sounds.  Second, Rhodes pianos often need to be taken to gigs, and weight is an important consideration.  Baltic birch plywood is awfully heavy, and thicker rather than denser is the way to get stiffness without excessive weight.   Here's the reason--the stiffness of a beam goes up as the cube of its thickness.  So, a little increase in thickness makes a big difference in stiffness.  That's why using a lighter wood panel with stiffeners can offer equal or better stiffness than a heavy wood panel with no stiffeners.

On another topic related to this thread, I think Fender often supplied pretty poor speakers in the suitcase pianos--I once owned a suitcase piano with the dullest sounding speakers known to man.  You can do much better these days by buying new speakers from Eminence.  Several other companies produce very good speakers as well.  Also, remember that 2, 8-ohm speakers in series provides 16 ohms, if that's what the amp needs.  There's no need to try to get 32-ohm speakers.

87
The Fender Rhodes Electric Piano / Re: Rhodes pickup screwdriver test
« on: February 06, 2018, 06:58:15 AM »
Thanks. I double-checked all the wiring again and again using a fine magnifying glass. Still can't find any breaks.  Some of the notes play just fine, even with the low output when doing a screwdriver tap.

If one pickup is bad would it cause others in the chain to produce a weak signal?

Measure the resistance of each group of 3 pickups and compare it to the pickups lower down the scale.  Look for any other anomalies of resistance you can probe around and check.

88
The Fender Rhodes Electric Piano / Re: Zinc Plating On Tone Bars
« on: January 31, 2018, 10:40:14 AM »
I'd be surprised if any plating method would add enough mass to make a tonebar unusable.

I agree-it's common for plating to be 0.0005"/12um or less.

89
Parts, Service, Maintenance & Repairs / Re: Balance Rail Felts
« on: January 30, 2018, 11:35:33 AM »
The paper punchings should go under the felts, not on top, though you will find some Rhodes made that way.

90
The Fender Rhodes Electric Piano / Re: Remove corrosion on metal parts?
« on: January 29, 2018, 12:25:57 PM »
The tines are steel, and steel rusts.  There are any number of chemical rust removers available;  I'd be tempted to try one of them.  Diluted muriatic acid (HCl) works well as a rust remover, but be careful if you want to go that route.

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