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False Beats-V Bar Shape and Pressure Bar height

Posted By: DanS

False Beats-V Bar Shape and Pressure Bar height - 10/03/16 02:54 AM

Hi all,

One of the pianos on which I practice tuning has false beats on almost every string from F3 - F5 (the middle section trichords). I simply can't get any workable tuning on the piano. I don't think it's just my lack of experience; I can get a pretty decent tuning on all the other pianos I practice on (not good enough to record Ravel on, but I've played tons of gigs on worse).

The bridge is in good condition, and the pins aren't loose. The notching isn't great, but it's certainly not bad enough to cause this many false beats. I tried the resting the screwdriver on the pins trick but it made no difference.

The Piano is a 1973 Kimball small console (40"). It was about 130cts low when I got it. Many of the strings are spaced too closely. I think the false beats have gotten worse since I've been trying to learn to tune (or maybe my ears have improved). Also, it has a very metallic buzzing kind of sound.

I'm thinking the pressure bar is too high, or maybe the shape of the V-bar is too round (or maybe I just need to restring it). I've included some pics. I'd love to get some feedback from the community. Thanks in advance.

[Linked Image]

[Linked Image]
Posted By: Chris Leslie

Re: False Beats-V Bar Shape and Pressure Bar height - 10/03/16 07:50 AM

If you have tried the usual tricks, why not change just a few strings and see how that goes.
Posted By: Gadzar

Re: False Beats-V Bar Shape and Pressure Bar height - 10/03/16 10:10 AM

I have zoomed in the image. Apparently, in the trichords, strings are touching each other.

The first thing I would do is to correctly space strings.
Posted By: DanS

Re: False Beats-V Bar Shape and Pressure Bar height - 10/03/16 03:32 PM

Good thinking Chris, I think I'll change the lowest couple of notes and see if that helps.

Gadzar, thanks for the tip. It's hard to see in the pic, but the strings aren't actually touching, although they are a bit too close.


Posted By: rysowers

Re: False Beats-V Bar Shape and Pressure Bar height - 10/03/16 03:45 PM

Tightening the pressure bar sounds like a good idea. The string angle looks a little gentle. More positive pressure on the upper bearing could help. It can also give more control when tuning, because it may make the strings less sensitive to slight tuning pin movements.

Did you put the felt in below the capo bar? Looks like a past attempt to quiet string noise. You will have to lower tension a lot before tightening the capo bar. But, what the heck! You need the tuning practice! .:)
Posted By: DanS

Re: False Beats-V Bar Shape and Pressure Bar height - 10/03/16 05:43 PM

I'll give that a try too, thanks. I didn't put in the felt, it came to me that way. How far should I lower the tension? Is 1/4 turn on each pin enough?
Posted By: Ed McMorrow, RPT

Re: False Beats-V Bar Shape and Pressure Bar height - 10/09/16 02:39 AM

All pianos with this mild steel rod string termination produce a "nasal" whine if not an outright buzz. I call it the "Kimball" tone because many Kimbal uprights used this type of string termination. You might try getting some phosphor bronze alloy wire of slightly smaller diameter to replace the mild steel presently there. You might want to shim the smaller diameter rod to sit higher in the groove too. I have never done this but I suspect it would improve tone if you also make sure the bearing angle is sufficient and the string spacing is done well. I suspect some of the "whine" in the sound is longitudinal waves reflected and the softer bronze will reduce the reflection of L-modes somewhat.
Posted By: rysowers

Re: False Beats-V Bar Shape and Pressure Bar height - 10/09/16 03:21 AM

I'm not sure about the 1/4" turn. That would certainly get the bar lower and would probably help things. I think Ed's advice sounds good and if you are going through the trouble of removing the string tension you might see if there is a way to change the material like he suggests.

Good luck and let us know if you have good results.
Posted By: BDB

Re: False Beats-V Bar Shape and Pressure Bar height - 10/09/16 07:14 PM

If someone called you to tune this piano, would you listen to it and tell the owner, "I am sorry, but I cannot tune it until I do umpteen dollars worth of work"? If you want to learn to tune pianos, you need to learn to tune the bad ones as well as the good ones. You cannot spend more than the amount of time that you can afford to give away to make it better. Sometimes that means only doing as good a job as you can. Afterwards, you might be able to say that it could be better if you did thus or so. But if you start out that way, the person who tunes it is going to get the job.

If you do offer to do more work, you should be absolutely sure that you can do it, and that it will make a difference to the owner, and not just you as the tuner.
Posted By: rysowers

Re: False Beats-V Bar Shape and Pressure Bar height - 10/09/16 09:41 PM

He said it was a piano that he practices on, so I assume this not a normal retail client piano. A practice piano is just right one to try new procedures without risking your reputation.
Posted By: DanS

Re: False Beats-V Bar Shape and Pressure Bar height - 10/10/16 12:19 AM

Yes, it is one of my pianos, one that I'm using to learn tuning/tech work.

I tried a bunch of stuff;

First I raised the pressure bar a tiny amount (turned the screws less then a 1/4 turn). I tuned the section and noticed a few new false beats. There was one where I could actually tighten one of the screws a small amount and get the FB to go away. Interesting...

Next I replaced the two lowest trichords (and practiced making coils with the old wire for about 2 hours). I'm not sure if this helped or not. There are still false beats. (I recorded each string before replacing, but I haven't compared them yet).

Next I released the tension from the strings and lowered the pressure bar. The screws didn't want to tighten anymore then they already were. I'm not sure if they were bottoming out (probably not) or just need to turned with a lot more force. Either way, I added a small washer to each screw so I could get the bar lower. I also re-spaced some of the strings. Some were pretty bad (my teacher said they left the factory that way). There was a definite improvement, although there are still a lot of false beats.
Posted By: DanS

Re: False Beats-V Bar Shape and Pressure Bar height - 10/10/16 12:24 AM

Originally Posted by Ed McMorrow, RPT
All pianos with this mild steel rod string termination produce a "nasal" whine if not an outright buzz. I call it the "Kimball" tone because many Kimbal uprights used this type of string termination. You might try getting some phosphor bronze alloy wire of slightly smaller diameter to replace the mild steel presently there. You might want to shim the smaller diameter rod to sit higher in the groove too. I have never done this but I suspect it would improve tone if you also make sure the bearing angle is sufficient and the string spacing is done well. I suspect some of the "whine" in the sound is longitudinal waves reflected and the softer bronze will reduce the reflection of L-modes somewhat.


I love this idea, but I think I'll wait a bit before attempting it. Two questions. 1, how would I shim the new wire? 2, how would I go about shaping the new wire?

Thanks!
Posted By: BDB

Re: False Beats-V Bar Shape and Pressure Bar height - 10/10/16 01:28 AM

Originally Posted by rysowers
He said it was a piano that he practices on, so I assume this not a normal retail client piano. A practice piano is just right one to try new procedures without risking your reputation.


Which makes it exactly the type of piano that he should know how to tune before doing any extensive work on it.

I read that myself. It was not clear whether it was his piano or someone else's, but either way, the first procedure to try is to tune it.
Posted By: rXd

Re: False Beats-V Bar Shape and Pressure Bar height - 10/10/16 07:57 AM

In answer to your original questions,
Firstly, the ghost marks on the bearing bar show that the strings of at least the first two trichords have been better spaced at some point in time. Deal with the spacing as best you can first, aiming for as straight a line as possible from the tuning pin into the line of the speaking length. There was a time when I could have told you which notes on what models would be problematic but that was long ago when I worked for a Kimball dealership.
Even on these pianos it is possible to do a halfway decent job, only occasionally resorting to discreet spacers in the non speaking length. (A narrow strip of thickish listing woven between the strings just above the pressure bar gives neat looking spacing in the area you have photographed where it is most needed).
You will have to compromise keeping the hammer spacing looking even and striking as centrally as possible. Damper adjustments may become necessary or moving strings might even cure existing faults.
On to tuning.
Falseness in this region is not uncommon, usually at a similar beat rate to fourths and fifths and causes confusion for the beginner. Experienced tuners might not even notice it.
In these cases you are dependent on RBI's, using them comparatively to verify that your fourths and fifths are tempered on the correct side and are sounding as convincing as you can get them. This is a good excercise in learning the comparative beat rates going outside the temperament octave and using sixths and tenths to verify fifths, etc. etc. if you don't already know them. (Learning them also helps when tuning in noisy environments)..

Posted By: DanS

Re: False Beats-V Bar Shape and Pressure Bar height - 10/11/16 02:20 AM

Amanda, thanks for the tips. I never would've thought about adding string spacers. Do you think the red felt between the strings is from the factory, or did someone do that after the fact?

BDB, I totally agree. I'm not doing any major work until I can tune it successfully. I did some minor work and it improved the false beats. The midrange still sounds like a ride cymbal with pennies taped on it, but that's the challenge. I have several pianos I practice tuning on, three are mine, and a few others I'm fortunate enough to have unlimited access to. This is by far the most challenging one. It's also the one I spent the first 4 or 5 months learning on. I'm still a long way from doing this professionally, but I'm working hard towards that end.
Posted By: rXd

Re: False Beats-V Bar Shape and Pressure Bar height - 10/11/16 06:54 AM

That felt looking blob is not factory. If the strip is made of felt it is not factory. The best material to use for that purpose is woven and needs to be positioned lower down (centrally or a bit lower looks better) and possibly slightly thicker material to be effective.
I would avoid lowering tension to do this.

Don't let strings contact pressure bar screws. This can cause unnecessary extra friction and consequent tuning difficulty.
Posted By: daniokeeper

Re: False Beats-V Bar Shape and Pressure Bar height - 10/11/16 11:38 AM

Here are instructions on how to correctly adjust the pressure bar and other things. These are instructions from a Kimball Troubleshooting Service Manual from the 1980's.

There links should open automatically in your browser if you have pdf viewer configured to do so. If not, you should be give the option of downloading.

http://daniokeeper.tripod.com/webonmediacontents/KTSG_pt9.pdf

http://daniokeeper.tripod.com/webonmediacontents/KTSG_pt9.pdf
Posted By: DanS

Re: False Beats-V Bar Shape and Pressure Bar height - 10/11/16 04:25 PM

These are great. Thanks Joe!
Posted By: Nathan M., RPT

Re: False Beats-V Bar Shape and Pressure Bar height - 10/11/16 05:38 PM

That bit about taking the bridge pins toward the string looks awfully fishy...
Posted By: BDB

Re: False Beats-V Bar Shape and Pressure Bar height - 10/11/16 05:54 PM

I thought that if Kimball spent as much care making their pianos as they did trying to correct the mistakes that they made, they would have made better pianos for less money.
Posted By: DanS

Re: False Beats-V Bar Shape and Pressure Bar height - 10/11/16 06:13 PM

Originally Posted by BDB
I thought that if Kimball spent as much care making their pianos as they did trying to correct the mistakes that they made, they would have made better pianos for less money.


That's the American assembly line philosophy. Get as many units out as possible and fix the problems afterwards. Don't ever stop production.
Posted By: daniokeeper

Re: False Beats-V Bar Shape and Pressure Bar height - 10/12/16 12:26 AM

Oops! It looks like I posted the same link twice. This is the additional link I wanted to post:

http://daniokeeper.tripod.com/webonmediacontents/ktsg_10.pdf
Posted By: daniokeeper

Re: False Beats-V Bar Shape and Pressure Bar height - 10/12/16 05:35 AM

Originally Posted by Nathan Monteleone
That bit about taking the bridge pins toward the string looks awfully fishy...


I don't understand your meaning.
Posted By: Gadzar

Re: False Beats-V Bar Shape and Pressure Bar height - 10/12/16 05:52 AM

I thought the same.

Don't you damage the bridge's wood by tapping on the pin towards the string?
Posted By: daniokeeper

Re: False Beats-V Bar Shape and Pressure Bar height - 10/12/16 05:58 AM

These were Kimball's published recommendations at the time for their pianos that were under warranty.

I had a Kimball dealership as a customer.

As I recall, at that time, Kimball had either laminated hardwood bridges or laminated hardwood caps. Also, the bridge pins were not short; they extended higher above the bridge... as I recall.

Even though it was about 30 years ago, I do remember questioning to myself at the time whether to follow these recommendations.

But, it was a Kimball piano and this was Kimball's recommended solution. If I ignored their advice and just went my own way, how could Kimball be responsible for honoring the warranty?

I did use this exact method successfully several times to correct buzzes. Of course, you're not hammering them like a nail. You just want to bend the pin maybe a few thousandths to stop the noise. Don't tap them at the base where the pin contacts the bridge. Tap near the top.

This rarely needed to be done, and then only on one or two pins.

The O.P.'s piano is a 1970's piano, not 1980's like these service manuals. He'll have to use his best judgment.
Posted By: rXd

Re: False Beats-V Bar Shape and Pressure Bar height - 10/12/16 10:53 AM

Some of these 'correct' procedures I always found questionable. Yes, a Philips screwdriver will slip out of the screw head and damage it before over torquing will twist the head off. Many high quality tools today are pozidriv especially those of European origin. They are not designed to slip out of the screw head and so can easily twist the head off those cheap screws. They are designed for craftspeople who can feel the torque even in a tight screw before it reaches dangerous levels. The Phillips system seems more of a diy affair or for factories where screws are driven in with a powerful drill.
The pressure bar was a soft material that would bow between the screws if tightened with string tension on and which of us would take the tension off a new piano where we are fighting for every bit of stability on a piano that may be back on a delivery truck in a few hours and most likely never be serviced ever again?

Like Joe, we all had to rely on our personal experience of higher quality instruments and some inventiveness to find legitimate, quick and safe ways to solve manufacturing problems.

The servicing booklet was an accurate reflection of the factory.
Posted By: Ed McMorrow, RPT

Re: False Beats-V Bar Shape and Pressure Bar height - 10/12/16 04:12 PM

Preferably bend the bridge pin on the non-speaking length side of the bridge. The back pins.
Posted By: daniokeeper

Re: False Beats-V Bar Shape and Pressure Bar height - 10/13/16 06:33 AM

Originally Posted by Ed McMorrow, RPT
Preferably bend the bridge pin on the non-speaking length side of the bridge. The back pins.


Absolutely! If possible. Sometimes the back pins were not accessible because of obstructions.

Fortunately, this was not a routine correction.

Another issue re the false beats the OP mentioned...
At the time, i was instructed that the pianos would arrive at the dealership at "a pitch higher than A440." My instructions were to tune the piano at that higher pitch at the dealership and then at A440 in the customer's home.
This I ignored. I always brought them back down to A440, which always took extra time. They would then want to start creeping back up in pitch. If I didn't do it this way, the piano would start creeping back up in pitch once tuned to A440 in the home.

It can be more challenging to bring a very sharp piano down to A440 than to raise a flat piano up to A440. As you lower the tension on some strings, the tension on the other strings increases. You risk string breakage and other damage. So, it might take several passes to do it safely. And at that time, I was working without an ETD. shocked smile

Also with brand new Kimballs, the pins were so very tight in the block that the pin would twist considerably before the foot would even begin to move.

Though it was 30+ years ago, I think I remember being told that Kimballs received only 5 or 7 tunings before leaving the factory. I've always suspected that they were tuned very sharp to try to help settle them faster, and this contributed to the false beat problem.

It is possible to damage a string without breaking it by using too much tension.. pulling it too high.
Posted By: Nathan M., RPT

Re: False Beats-V Bar Shape and Pressure Bar height - 10/13/16 01:51 PM

Originally Posted by daniokeeper
Originally Posted by Nathan Monteleone
That bit about taking the bridge pins toward the string looks awfully fishy...


I don't understand your meaning.


Basically given the tendency of flagpoling front bridge pins to cause false beats, having the pin bent away from the anchoring wood on the other side seemed potentially problematic.

But It didn't register for me that you could only do it to the back bridge pin as Ed said...
Posted By: DanS

Re: False Beats-V Bar Shape and Pressure Bar height - 10/13/16 03:54 PM

Here's an update.

I did some work adjusting the pressure bar, realigned several trichords and tuned the piano. It's a big improvement. I also put it back together (music desk, fallboard, keyslip etc) and that made even more improvement in the overall sound. I think a lot of my problem with the sound of the piano was the harsh buzzing, which is much less noticeable with the piano back together. I can play a major 7 chord, and it sounds good which I couldn't do a month ago.

Thank you all for your assistance.
Posted By: Goof

Re: False Beats-V Bar Shape and Pressure Bar height - 10/13/16 04:02 PM

I have posted on the same problem with trichords on my 1945 B.Brock upright. For me it was the fact that some of the stings were too close.
All I did was loosen the ofending strings then just below the capo bar I pushed in small bits of hard plastic to move the strings away from each other. This does not look too good but then who plays an upright with it's front off!
You may have some troble where strings run close to a capo screw. I recon that the odd screw left out would probably not make much difference. Failing this one could, if there is space move a hammer side ways.
If I were to ever buy another piano then agafes(sp) would be essential.
Posted By: daniokeeper

Re: False Beats-V Bar Shape and Pressure Bar height - 10/14/16 02:03 AM

Hi Goof, Using shoe pegs to separate the strings is traditional. It goes way back.
Posted By: Del

Re: False Beats-V Bar Shape and Pressure Bar height - 10/16/16 03:12 AM

There were a number of problems with Kimball pianos of that era. They were budget pianos that lacked design finesse and construction quality.

In today's market they also lack anything like top (or even medium) dollar. Hence anything you do to the piano will have to be charged to "education." You will not be able to recover the cost of any significant improvements you might make to the piano. You can, however, learn a great deal. So it's a question of how much you are willing to spend on education.

There are undoubtedly problems with the bridges. It wouldn't be a mid-20th century Kimball if there were not problems with the bridges. Assuming the string offset is adequate (not always a safe assumption with Kimballs) then a drop or two of thin CA adhesive on the back side of the pins can help. Otherwise more heroic measures might be required.

Ed McMorrow is quite right in his comments about the steel rod used as a V-bar in these pianos. It was used because it was cheaper to cast a groove in the V-bar and set in the steel rod than to surface the as-cast V-bar. The steel rod is too hard and, perhaps more importantly, it is not well seated. Examine the V-bar groove -- it is rough and uneven. (At least it has been on every Kimball of this type I've ever had the misfortune of servicing.)

There is not much you can do about the string spacing problems except try to space the strings as best you can. But if you want to do some educational experimentation there is a lot you can do to improve the performance of these pianos. Most of which will involve restringing the piano.

You can evaluate (and greatly improve)the string scale. You can clean up the bridges. You can replace the steel rod with a brass (or bronze) rod. And, while you're at it, you can bed that rod so that there is a better, more solid, termination of the speaking length. Bed it in a filled (preferably with iron powder) epoxy. It's not difficult. Just fill the "U" indent on the top of the V-bar with your epoxy matrix and set (and figure out how to clamp) the new rod in place. When cured clean everything up and you're good to go. (This will, by the way, help even the steel rod.)

All of this goes way beyond what is economically practical on a Kimball piano of this price. The payoff is in education. Only you can determine whether this is worth the investment in time and treasure.

ddf
Posted By: DanS

Re: False Beats-V Bar Shape and Pressure Bar height - 10/16/16 11:21 PM

Thanks for the tips Del. I would like to try the new V-bar, but I need to spend my time dialing in my tuning first; this seems like a project that makes sense once I'm already in the field.
Posted By: Dale Fox

Re: False Beats-V Bar Shape and Pressure Bar height - 10/17/16 02:46 AM

Del, do you know of a place to locate hardness specs for phosphor bronze compared to mild steel or annealed drill rod? I'm looking for a supply to use regularly for capo inserts but thought you might know off hand a supplier and grade that you would recommend. I just had an old model "O" with a terrible amount of issues in the capo and corresponding tonal issues. Lots of voids and casting sand embedded in the surface. Ended up using annealed drill rod and it sounds great but always interested in trying something a bit more appropriate.

Nice to see you back on PW a bit.

Dale
Posted By: Del

Re: False Beats-V Bar Shape and Pressure Bar height - 10/17/16 07:02 PM

Originally Posted by Dale Fox
Del, do you know of a place to locate hardness specs for phosphor bronze compared to mild steel or annealed drill rod? I'm looking for a supply to use regularly for capo inserts but thought you might know off hand a supplier and grade that you would recommend. I just had an old model "O" with a terrible amount of issues in the capo and corresponding tonal issues. Lots of voids and casting sand embedded in the surface. Ended up using annealed drill rod and it sounds great but always interested in trying something a bit more appropriate.

I go to my very old (1986) copy of Materials Handbook. If it's not in there you probably don't need to be using it.

I haven't purchased any of this for a long time but I think my last batch came from "Online Metals." I could be wrong.

ddf
Posted By: Ed McMorrow, RPT

Re: False Beats-V Bar Shape and Pressure Bar height - 10/18/16 05:45 AM

Dale Fox, It might be less work to just drill the capo for upside down agraffes.
Posted By: AndrewCabana

Re: False Beats-V Bar Shape and Pressure Bar height - 10/19/16 12:52 PM

Yes. I often get overagitated with small pianos because of their harsh and loud Asian hammer attacks but it is amazing how different it sounds with the cover back on. Back on false beats: in the Riblitz book there is a section on this and one of the things he mentions is pitch raises causing false beats. A small kink or bend in the string can cause what I call " termination confusion" which is a false beat. So a piano that was as messed up on the tuning as you described might be problematic temporarilly even without the other problems you mentioned
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