Author Topic: It may be time for a new keyboard!  (Read 12013 times)

0 Members and 1 Guest are viewing this topic.

Offline SciNote

It may be time for a new keyboard!
« on: January 25, 2019, 08:17:04 AM »
I know I haven't been on here as much recently.  I recently got a new (for me) car, and I have been busy customizing it.  But I decided to play some songs on my PSR-E433 last night, and some of the sounds just didn't sound right.  I've noticed this other times, recently, as well.  I isolated it to adding reverb to certain sounds, like piano.  It causes the sound to get distorted, kind of like the sound some portable audio equipment may make when the batteries are running low, but in this case, I am using an AC adaptor.

Has anyone else ever seen this?  I can't believe this is normal and that I never noticed it before.  And it doesn't happen on all sounds -- or at least, I don't notice it as much on certain sounds.  I notice it most on piano and strings.  I'm wondering if it is a result of when my keyboard accidentally slammed on the floor a little over a year ago (I temporarily and carefully leaned it up against up against a couch on its edge on a tile floor, and it slid out and slammed on the floor).  I tried the reset procedure of turning it on while holding down the highest key, and that didn't make a difference.

I guess I could get it looked at, but it's long out of warranty, so it would probably cost more than worthwhile to get a professional tech to look at it.  So, I will probably get a new keyboard soon.  Most likely, a PSR-E463.
Bob
Current: Yamaha PSR-E433 (x2), Roland GAIA SH-01, Casio CDP-200R, Casio MT-68 (wired to bass pedals)
Past: Yamaha PSR-520, PSR-510, PSR-500, DX-7, D-80 home organ, and a few Casios
 

Fantomas

  • Guest
Re: It may be time for a new keyboard!
« Reply #1 on: January 25, 2019, 08:34:28 AM »
That's strange.
Did you try with headphones or external speakers ?
The slamming of your keyboard can't have  affected only some specific sounds.

Upgrading from 433 to 463 will not be a great improvement.
 

Offline SciNote

Re: It may be time for a new keyboard!
« Reply #2 on: January 25, 2019, 10:09:42 AM »
Yes, same issue with external amplified speakers.  Have not tried headphones. And yeah, not a grand difference from the 433 to 463, but they have been adding features over the years... DSP, faster save time when storing registrations, 48 note polyphony, audio-in, sampling, and tunable scales are notable.  But, yes, for what I use, there isn't a great difference than my 433, which is why I've held on to it for so long.  But if it isn't sounding right, I'll need to replace it.

EDIT: Almost forgot about the ability to add reverb and chorus to the drums/style.  That makes a big difference, though I don't believe the settings are saved unless you save a style to a registration, which I don't usually do.  That means that if I want to use reverb/chorus for drums for live playing, I have to set the parameters each time I turn the keyboard on, and possibly every time I change styles -- I cannot remember if the style reverb/chorus settings are retained when changing styles, but I have a funny feeling that they are not.
« Last Edit: January 25, 2019, 10:14:34 AM by SciNote »
Bob
Current: Yamaha PSR-E433 (x2), Roland GAIA SH-01, Casio CDP-200R, Casio MT-68 (wired to bass pedals)
Past: Yamaha PSR-520, PSR-510, PSR-500, DX-7, D-80 home organ, and a few Casios
 

SeaGtGruff

  • Guest
Re: It may be time for a new keyboard!
« Reply #3 on: January 25, 2019, 10:23:46 AM »
If you're thinking about the PSR-E463, you might consider the PSR-EW410 instead. Yes, it will cost a bit more-- but having a wider keyboard can make more of a difference than you might expect, plus the PSR-EW410 has stronger amplifiers, better audio output options, and the possibility of adding the KS-SW100 subwoofer.
 

Roy_T

  • Guest
Re: It may be time for a new keyboard!
« Reply #4 on: January 25, 2019, 10:46:49 AM »

"Upgrading from 433 to 463 will not be a great improvement."


But when most of us "need" to replace a keyboard, we are financially constrained to looking for what is "affordable", rather than upgrading to the next higher model.  If somethiing were to happen to my PSR-E433 right now, I would have to consider the E463, but with the improvements over the last few years, I would still consider that an "upgrade", of sorts.  Although, I think there are a couple of members here who preferred the sound and/or keybed feel of the E433 over the newer models.  I would most likely take Michael's suggestion of the EW410, as I am a long, long time fan of 76 synth action keys.

Best of luck with resolving your dilemma, Bob !

Roy
« Last Edit: January 25, 2019, 10:57:28 AM by Roy_T »
 

Offline vbdx66

Re: It may be time for a new keyboard!
« Reply #5 on: January 25, 2019, 10:48:41 AM »
Hi Bob,

I had the PSR E433 for some years and like it very much, then sold it when Imbought my DGX650, bought it again as a second-hand device, resold it and had briefly a PSR E463 last year.

Yes, the PSRE463 has some features which the E433 doesn’t have but the only one I really found useful is the possibility to record audio directly on an USB stick - this is really convenient. And honestly, the keybed of the E433 is vastly superior to the keybed of all its successors from the E443 to the E463.

You might consider the following options: as Michael said, the EW410. Or else, a PSR S670, or why not trying a second-hand E433 if you really like this keyboard and are used to it?

Just my two cents,

Regards,

Vinciane
Past keyboards: PSR E313, PSR E413, PSR E433, PSR S550, DGX 640, upright piano.
Now: DGX 650, Casio CT-X800.
 

Offline SciNote

Re: It may be time for a new keyboard!
« Reply #6 on: January 26, 2019, 08:10:07 AM »
Hi Bob,

...

You might consider the following options: as Michael said, the EW410. Or else, a PSR S670, or why not trying a second-hand E433 if you really like this keyboard and are used to it?

Just my two cents,

Regards,

Vinciane

Because they are nearly impossible to find.  I rarely see them on E-bay.  I have yet to see one on my local Craigslist.  I've seen one or two on other sites, like "Reverb".  And when I do see them (or other used PSR-E433, 443, or 453 boards), they are often insanely priced.  $150 for a five year old keyboard that was only $250 when new?  Sometimes, these sellers are asking a price at or greater than the original street price!  Might as well buy a new keyboard with a warranty.

EDIT:  Here's an example for a PSR-E463...

https://lakeland.craigslist.org/ele/d/lakeland-yamaha-psr-e463/6776067705.html

Seriously, $399?  Oh, "price negotiable" -- LOL!  Yeah, since I can go to the local music store and buy a brand new one for $120 less, I would hope so!  Or, "never opened"... except right there in the photo in the ad!
« Last Edit: January 26, 2019, 08:30:42 AM by SciNote »
Bob
Current: Yamaha PSR-E433 (x2), Roland GAIA SH-01, Casio CDP-200R, Casio MT-68 (wired to bass pedals)
Past: Yamaha PSR-520, PSR-510, PSR-500, DX-7, D-80 home organ, and a few Casios
 

Offline vbdx66

Re: It may be time for a new keyboard!
« Reply #7 on: January 26, 2019, 06:27:50 PM »
Well indeed these prices seem insane. It might be a question of luck, though. Maybe in a couple of days one of your neighbours will want to get rid of his PSR E433 for eighty bucks, who knows?

Good luck for your quest for a new keyboard,

Regards,

Vinciane
Past keyboards: PSR E313, PSR E413, PSR E433, PSR S550, DGX 640, upright piano.
Now: DGX 650, Casio CT-X800.
 

SeaGtGruff

  • Guest
Re: It may be time for a new keyboard!
« Reply #8 on: January 26, 2019, 10:37:04 PM »
And when I do see them (or other used PSR-E433, 443, or 453 boards), they are often insanely priced.  $150 for a five year old keyboard that was only $250 when new?

That's not necessarily a bad price for a used PSR-E433, E443, or E453, depending on its age, condition, and whether anything else comes with it, such as the Survival Kit, stand, bench, etc. I often see people trying to sell used PSR-E2xx and E3xx models for more than I think they're worth, but the person will also be trying to get rid of things like song books and sheet music that they'd bought when they thought they were going to learn to play the keyboard and become a musical star.

Seriously, $399?

Now, that is totally unreasonable. I'm inclined to suspect that the person trying to sell it isn't the person who actually purchased it-- e.g., maybe one of their parents bought it but then passed away-- so in trying to see what it's worth they went to Yamaha's web site and saw its MSRP of $479. Or perhaps they had searched for "PSR-E463" on a store's web site and it came up with the PSR-EW410 instead? Then again, perhaps they're just criminally insane?
 

Offline Toril S

Re: It may be time for a new keyboard!
« Reply #9 on: January 27, 2019, 01:20:30 AM »
Survival kit?😀
Toril S

Genos, Tyros 5, PSR S975, PSR 2100
and PSR-47.
Former keyboards: PSR-S970.

https://www.youtube.com/channel/UCLVwWdb36Yd3LMBjAnm6pTQ?view_as=subscriber



Toril's PSR Performer Page
 

SeaGtGruff

  • Guest
Re: It may be time for a new keyboard!
« Reply #10 on: January 27, 2019, 08:24:04 AM »
The PSR-E models don’t usually include an AC power adapter, so you need to buy the power adapter separately if you don’t want to have to use batteries. The Survival Kit is a box that includes an AC power adapter, a cheap sustain foot switch, a cheap pair of headphones, a DVD about how to play a keyboard using styles, an extended warranty that doubles the warranty from one year to two years, and some coupons or discount offers for various products or software for the keyboard. There are a few different Survival Kits so you need to be sure to get the one that has the correct power adapter for your particular model. I think the Survival Kits used to cost about $30 several years ago when I bought my PSR-E433, but I think the last one I had to buy cost about $35 or maybe $40– I would need to look at the box to see. Anyway, if the original owner is selling their old keyboard plus the Survival Kit that they bought for it, they might want to charge a little more.

Offline vbdx66

Re: It may be time for a new keyboard!
« Reply #11 on: January 27, 2019, 09:07:11 AM »
Hi Michael,

In France, every PSR under the sun comes with a power adapter and a full two years warranty  8) 8) 8)

Have a nice Sunday everybody,

Vinciane
Past keyboards: PSR E313, PSR E413, PSR E433, PSR S550, DGX 640, upright piano.
Now: DGX 650, Casio CT-X800.
 

SeaGtGruff

  • Guest
Re: It may be time for a new keyboard!
« Reply #12 on: January 27, 2019, 10:21:04 AM »
In France, every PSR under the sun comes with a power adapter and a full two years warranty  8) 8) 8)

Yes, I've been told that in the UK every keyboard must come with a full two years warranty. Apparently it's something to do with the consumer protection laws in different parts of the world. So that apparently means that the USA government doesn't require companies to give consumers a full two years warranty, only a full one year warranty. But I haven't looked into those two "apparent" facts to confirm them.

Offline Toril S

Re: It may be time for a new keyboard!
« Reply #13 on: January 27, 2019, 10:23:32 AM »
In Norway too!
Toril S

Genos, Tyros 5, PSR S975, PSR 2100
and PSR-47.
Former keyboards: PSR-S970.

https://www.youtube.com/channel/UCLVwWdb36Yd3LMBjAnm6pTQ?view_as=subscriber



Toril's PSR Performer Page
 

Offline vbdx66

Re: It may be time for a new keyboard!
« Reply #14 on: January 27, 2019, 11:11:30 AM »
Hi Michael,

As for France I can confirm that the law requires that all electronic devices must come with a two-year warranty. And here nobody would even consider buying a keyboard without an AC adapter - it would be like buying a car without wheels  ;D

Regards,

Vimciane
Past keyboards: PSR E313, PSR E413, PSR E433, PSR S550, DGX 640, upright piano.
Now: DGX 650, Casio CT-X800.
 

Offline panos

Re: It may be time for a new keyboard!
« Reply #15 on: January 27, 2019, 12:09:10 PM »
Survival kit?😀

It's what you really need Toril when you play Tomb Raider but also when you play Tomb Raider's Venice Violins on a keyboard  ;D
https://www.youtube.com/watch?v=lYLlckc9Ph8

2-year guarantee is a law for all EU countries:
https://europa.eu/youreurope/citizens/consumers/shopping/guarantees-returns/index_en.htm

about faulty products:
https://europa.eu/youreurope/citizens/consumers/shopping/guarantees-returns/faq/index_en.htm

There is an option to the pages for translation for all EU languages
(at the top, center)

Offline SciNote

Re: It may be time for a new keyboard!
« Reply #16 on: February 05, 2019, 03:27:11 AM »
I've made a small sample recording of the distortion that I'm talking about.  I'll admit that it is not dramatic, but it is noticeable.  In this recording, I start with the basic "portable grand" sound on the PSR-E433.  Then, on the second playing of the sequence of notes, I add Hall3 reverb, turned up about half way using the live control knob.  Then on the third playing of the sequence, I turn the reverb up all the way.  The distortion can especially be heard on the last note played.  Let me know what you think.

https://app.box.com/s/hygo8ykywsq4j9a2uyvdssyw5pbuoa11

EDIT: Here's a better sample.  Just a simple repetition of notes to illustrate the distortion.  The first five notes are "dry", with no reverb, the second five notes have half reverb, and the last five have it turned up all the way.  It seems much more noticeable in this recording.

https://app.box.com/s/fq96opkjtxn5dupekuqqd49zipa742sx
« Last Edit: February 05, 2019, 03:49:31 AM by SciNote »
Bob
Current: Yamaha PSR-E433 (x2), Roland GAIA SH-01, Casio CDP-200R, Casio MT-68 (wired to bass pedals)
Past: Yamaha PSR-520, PSR-510, PSR-500, DX-7, D-80 home organ, and a few Casios
 

Offline vbdx66

Re: It may be time for a new keyboard!
« Reply #17 on: February 05, 2019, 09:08:53 AM »
Hi Bob,

I listened to the two samples you uploaded and I don’t ear anything strange there  :o

I suspect that the “distorsion” you are talking about simply comes from adding too much reverb to some sounds. I have had the E433 for a couple of years and I don’t ear anything wrong in your samples.

If maybe you could upload a few more samples?

What I’d suggest for you in the meantime is trying to reproduce the same experience on another E433 to see if you get the same result. Or better, give here the detailed settings you used to make your samples, to see if other E433 owners get the same result as you.

It may simply be that with the years, your ear is getting more experienced and you are beginning to ear the little imperfections in the sounds of your E433, without it being faulty.

Hope this helps,

Regards,

Vinciane
Past keyboards: PSR E313, PSR E413, PSR E433, PSR S550, DGX 640, upright piano.
Now: DGX 650, Casio CT-X800.
 

SeaGtGruff

  • Guest
Re: It may be time for a new keyboard!
« Reply #18 on: February 05, 2019, 09:25:28 AM »
The recent "Is this normal?" thread (or whatever the exact name was) might be of interest, since it turns out that a keyboard's speaker grille or other parts, or even a music stand, etc., can exhibit sympathetic vibrations in response to certain frequencies or combinations of harmonic overtones. I think that thread was in a Genos subforum, but I've seen similar posts/complaints about "weird noises" when a specific note is played using a specific voice on a DGX keyboard, so I suspect that this sort of issue due to sympathetic vibration can be more common than realized. I'm suddenly reminded of times when I was living in an apartment and a large truck happened to be going down the street, causing the entire building to suddenly start vibrating in response! :o
 

Offline SciNote

Re: It may be time for a new keyboard!
« Reply #19 on: February 05, 2019, 09:36:29 AM »
Well as I can hear the distortion in the recording, which was done through a USB connection, that rules out any external sources of vibration, such as a music stand or loose cables.  In the second recording, are you saying you cannot hear the distortion in the third set of notes, around 15 seconds in, when the reverb is turned all the way up?

The settings to try is simply what I listed above... set the basic piano using the portable grand button (which turns off all special effects), then set the reverb type to Hall3, then hit a single note repeatedly, holding it down for a second or two each time, while increasing the reverb amount using the live control knob.  I didn't try notes throughout the keyboard, but clearly, I can hear it at least in the middle range of the keyboard.

I'd be more than happy to try it on another PSR-E433, except that I know of no other one within miles of me!  I'm sure someone has one, but I have no idea of who.  But, at the music store, I did NOT hear the distortion on the PSR-E463.

I'm wondering if it is just the reverb circuit is just going bad.  And on that note, I wonder if there is just simply a chip in the keyboard that manages the reverb, so that simply replacing that chip would solve the problem.  I did notice that I previously had the main voice level set at 122 (I lowered it to 100 for the samples I recorded above).  Maybe I just overloaded the reverb chip and burned it out.

I played around with the E463 again today, and while I like its features, I have to agree that the key feel is not up to the standard of the E433.  In fact, there was an E263 sitting right above it which actually had a slightly better key feel than the E463.  Almost tempting to consider a Frankenstein maneuver by replacing the key-bed of the E463 with the one from my E433.  Wonder if that would work!  Of course, even if it did, that would shoot down the warranty!
« Last Edit: February 05, 2019, 09:48:06 AM by SciNote »
Bob
Current: Yamaha PSR-E433 (x2), Roland GAIA SH-01, Casio CDP-200R, Casio MT-68 (wired to bass pedals)
Past: Yamaha PSR-520, PSR-510, PSR-500, DX-7, D-80 home organ, and a few Casios
 

SeaGtGruff

  • Guest
Re: It may be time for a new keyboard!
« Reply #20 on: February 05, 2019, 10:13:05 AM »
Well as I can hear the distortion in the recording, which was done through a USB connection, that rules out any external sources of vibration, such as a music stand or loose cables.

Yes, that’s a good point. :)
 

Offline SciNote

Re: It may be time for a new keyboard!
« Reply #21 on: February 05, 2019, 12:01:28 PM »
Michael, can you hear the distortion in the recording?  Vinciane said it sounded normal.  What do you think?
Bob
Current: Yamaha PSR-E433 (x2), Roland GAIA SH-01, Casio CDP-200R, Casio MT-68 (wired to bass pedals)
Past: Yamaha PSR-520, PSR-510, PSR-500, DX-7, D-80 home organ, and a few Casios
 

Offline vbdx66

Re: It may be time for a new keyboard!
« Reply #22 on: February 05, 2019, 01:42:35 PM »
Hi Michael,

Unfortunately as you know I don’t have my E433 any more. Besides listening to Bob’s recording, could your maybe try to reproduce exactly what he did on your own E433 and listen to find any difference, or even post your own sample here so that we could compare both?

That way me might be able to find out whether Bob’s E433 is really faulty, or whether it is just a « normal » flaw in a somewhat already outdated keyboard. By that, I mean that Bob’s keyboard might be perfectly OK, but because technology has made big leaps since 2012, Bob might simply be more aware of some flaws of the E433 that he might not have noticed a few years back.

Personally, when I got a E433 back home for a few weeks last year, I noticed that I found many of the styles pretty outdated whereas I used to found them pretty realistic (for a lower-end keyboard) back in 2012.

Vinciane
Past keyboards: PSR E313, PSR E413, PSR E433, PSR S550, DGX 640, upright piano.
Now: DGX 650, Casio CT-X800.
 

SeaGtGruff

  • Guest
Re: It may be time for a new keyboard!
« Reply #23 on: February 05, 2019, 01:50:40 PM »
I’ll dig out my PSR-E433 later and try it.
 
The following users thanked this post: vbdx66

Offline SciNote

Re: It may be time for a new keyboard!
« Reply #24 on: February 06, 2019, 05:40:25 AM »
Yep, that could definitely be helpful if you could post a sample to compare.  Again, I'm just using the simple portable grand piano in my sample, with the main voice set to 100 and no special effects turned on except for reverb as I gradually add it to show the distortion.  I'm using Hall3 reverb.  And when I recorded to Audacity, the only tweak that I did to the digital recording with Audacity's features is to simply amplify the volume level to -0.3 dB so that the sound would be more full and easier to hear in the recording.  But rest assured, this did not add or alter the distortion that I hear, as I hear it live from the keyboard's speakers as well as from external powered speakers.
Bob
Current: Yamaha PSR-E433 (x2), Roland GAIA SH-01, Casio CDP-200R, Casio MT-68 (wired to bass pedals)
Past: Yamaha PSR-520, PSR-510, PSR-500, DX-7, D-80 home organ, and a few Casios
 

Offline DerekA

Re: It may be time for a new keyboard!
« Reply #25 on: February 06, 2019, 10:16:59 PM »
These are digital signal processors, so I doubt you could damage a chip and get partial results. Its not like an analog circuit where something can come loose.

I think what you are hearing is the "early reflection" portion of the reverb algorithm.

The reverb on the PSRE is decent, but when you push it too far - like you've done here - it becomes too harsh. The digital model isn't detailed enough, and you get signal clipping which you hear as unwanted harmonics.

The higher level keyboards - S, Tyros, Genos - use smoother effect alhorithms and also offer control over various parameters.
Genos
 
The following users thanked this post: vbdx66

Offline SciNote

Re: It may be time for a new keyboard!
« Reply #26 on: February 09, 2019, 07:01:08 AM »
I understand what you're saying, but if that was the case, I really think I would've noticed this earlier in the 5+ years I have owned, played, and recorded music using this keyboard.  Counting from my first lesson, I have been playing keyboards since March 21, 1978, so I have some experience with the overall sound they produce, so I really don't think this is the case of my ear just getting more sensitive to this type of distortion.

With the architecture of these keyboards, does the reverb circuit produce the effect while the sound is essentially still a bunch of 1's and 0's in the digital mode?  Because, yes, if that's the case, then I doubt that just "overloading" the reverb would damage it because it's all still just data at that point.  But if the reverb circuit is in line with the signal after the signal is converted to analog, then I could imagine its input being overloaded if I kept the main volume turned up too high over the years.  Or, it could simply be a case of a component going bad, as can happen in any electronic product.
Bob
Current: Yamaha PSR-E433 (x2), Roland GAIA SH-01, Casio CDP-200R, Casio MT-68 (wired to bass pedals)
Past: Yamaha PSR-520, PSR-510, PSR-500, DX-7, D-80 home organ, and a few Casios
 

Offline pjd

Re: It may be time for a new keyboard!
« Reply #27 on: February 09, 2019, 03:01:17 PM »
Tone generation and effects are entirely digital.

-- pj
 

Offline SciNote

Re: It may be time for a new keyboard!
« Reply #28 on: February 25, 2019, 08:32:28 AM »
Well, I haven't come up with a decision yet, but I have come up with an idea.  I can get an external stereo reverb unit and hook it up to my E433, and then redo all of my registrations to set the internal reverb to zero.  In reality, I don't really "finesse" the use of the reverb, as I usually just use a moderate amount of "Hall3" on almost all settings.  So, the fact that an external reverb unit's settings cannot be tied to a registration would not be much of a concern to me.  In fact, an advantage is that it would also provide reverb to the drums, which would likely liven up their sound.  I saw a Behringer unit for about $40 on Amazon, and if I really want to get creative, I can Frankenstein the project and actually take the reverb unit apart and wire and mount it inside the E433, and mount the controls to small panel on the far right side of the keyboard.

This would allow me to keep the E433, with its superior key feel.  And, while this may be an opinion in the minority, I like how the E433 has almost all of its controls in rows right by the keyboard, instead of having more controls further up, next to the display.  This makes it better when stacking keyboards and other equipment, as it allows more of the keyboard to be covered by something mounted over it on a rack (like another keyboard or mixing/amp equipment), while still allowing access to the controls.
Bob
Current: Yamaha PSR-E433 (x2), Roland GAIA SH-01, Casio CDP-200R, Casio MT-68 (wired to bass pedals)
Past: Yamaha PSR-520, PSR-510, PSR-500, DX-7, D-80 home organ, and a few Casios
 

Offline panos

Re: It may be time for a new keyboard!
« Reply #29 on: February 25, 2019, 10:01:49 PM »
Scinote I just listened to your recordings and there is a distortion but I find it normal when we use an effect that is loud enough as the original voice.
In my model the original piano voice when i turn on the keyboard has preset the basic hall effect at level 18 out of 127 max.
If I turn it on to 127 lvl I don't really care how much or less distorted is  the sound compared to your recording because there is no way my ears can tolerate that sound anyway.
Same happens to all kinds of effects.
If I turn them to the max they can change a sound so much so there is no harmony at all to the original sound wave which is supposed to be a note and not just an accidental sound.
« Last Edit: February 25, 2019, 10:04:14 PM by panos »
 

Offline SciNote

Re: It may be time for a new keyboard!
« Reply #30 on: February 26, 2019, 04:13:17 AM »
Yes, there is more distortion when the reverb is turned all the way up.  But there is still distortion when it is half way up, as well -- just not as much.  And maybe I am just hearing things differently, but I did not notice this in the previous years that I've owned the keyboard, and it doesn't seem to be there -- at least not as prominently -- on the new E463, though I'll have to take another listen to it.

Normally, I use a moderate amount of reverb on my main/dual voice patches -- I rarely have it cranked to 127.  The main time I do that is on the split voice if it is the case that I want as much of a sustaining effect as possible, as the PSR-E400's do not allow the sustain pedal to provide sustain to the left side of a split keyboard.  And as those notes are usually lower in pitch, I don't notice the effect there, as much.  I mainly hear it in the melodies and right-hand chords that I play.
Bob
Current: Yamaha PSR-E433 (x2), Roland GAIA SH-01, Casio CDP-200R, Casio MT-68 (wired to bass pedals)
Past: Yamaha PSR-520, PSR-510, PSR-500, DX-7, D-80 home organ, and a few Casios