Hi all,

I did a search for "Roslau" and "Piano Wire" hoping I could educate myself on the subject, now my head is spinning..
First of all, no one seems to have a common agreement on which type of wire is "better": American techs love the Mapes Gold, Europeans like Paullelo or Roslau, it also seems no one bothered to "scientifically" compare them as far as I can tell, I heard about a few experiments but they were not controlled. Then secondly, you have words I can't even spell like inharmonicity, breaking tension, fundamentals, partials, so many different terms and aspects, can someone please type up an "idiot's guide to piano strings" for this poor lost fellow? The reason is because I've been considering replacing the strings on my Bosie Imperial from 1967, simply because the treble sounds very dead and the bass, although nice doesn't have the wow effect one can expect. I've watched thousands of videos of Imperials online (with high quality headphones) and I can guarantee they're capable of a more "singing" strident treble and thunderous bass than my instrument is currently offering me (even rebuilt ones). I've had the hammers/shanks/flanges replaced last year by a professional and that did improve the sound a bit, but not as much as I was hoping for. I wish there could be more "loudness" or "power" to the sound, in other words, I'd like the treble to be more "piercing" and the bass to be more "vibrant". Also, mind you, I do have the piano in a humidity controlled environment set to 55% year round. If anything, getting more educated on all aspects of piano wire should allow me to form a better decision. I just don't want to have the strings replaced and then not see the results I was expecting. Thank you everyone!

Have you had the hammers voiced?

Bosie imperial won't have a thunderous bass like a Steinway but it should be full, colorful and powerful.

If the wire chosen conforms to the standard parameters like inharmonicity, loudness sustain, tension and others it's going to be ok. If you are interested in those physical parameters a great book is "the calculating technician" by Dave Roberts

Yes the hammers were voiced and the technician even used a solution to harden the already hard Renner hammers in a small section in the "killer" octave to see if that would help, it didn't!!

There are a few facts about piano strings, and one of them is that the longer the speaking length for a given note, the higher the tension must be, if the gauge of the wire is not changed. So concert grand strings tend to be a higher tension than smaller pianos, which is hard on them. There is a lot of tension on very little cross-section area. Metal fatigue sets in, the wire becomes work-hardened, and the sound becomes constricted.

Bösendorfer scales seem to be quite well calculated, so it may be that your strings are on their last legs.

On the other hand, hard hammers may bounce off the strings so fast that the full power of the hammer blow may not be transmitted to them. The solution is not to harden the hammers more, but to soften them underneath, to allow the hammer to work like a dead-blow hammer. A hard surface keeps definition to the tone, but some cushion below adds power.

Thanks for your insight, the only thing I'd ask is, to please not focus so much on my particular piano but to just offer me some insight in general about piano strings, the reason I mentioned my specific case is to offer a little background on what I'm going to use this information for. Thanks!

The problem is that there is not a lot of information that can be conveyed without experience, and people's interpretations of the experience are often a matter of opinion. It is hard to convey without examples, and your example is the one we have.

And so many factors other than the strings may be involved.

Exactly, David. Thank you.

While we cannot spoonfeed complete dissertations on demand, we can refer you to other threads that will give you a better understanding of the gestalt. One of the most recent being the thread concerning how often a piano should be fully restored. You can't miss it, the title is all in upper case. There's a lot of information about strings and their relationship to the rest of the piano there and in many other threads.

Do your homework then feel free to ask for clarification on specific points.

The strings on your piano are almost 50 years old. Would the tone be improved by replacing them? Yes, and any of the 3 makers named will do that, with slightly different results. But, as David suggests, the problems may not be in the strings.

The comments about the killer octave and the overall deadness may be telling. What has not been mentioned yet is what kind of shape the soundboard is in. I would encourage you to engage a competent rebuilder to examine the soundboard for crown and downbearing and give you a report. It is within the realm of possibility that you have a dead soundboard; if so, new hammers and/or strings won't get you there.

That said, BDB has it somewhat backwards when he says that a hard hammer will bounce off the strings very fast. The opposite is true. A new Renner hammer will be like a stone being dropped on the pavement in your driveway. Thunk!! No bounce. The hammer remains in contact with the strings for too long and absorbs energy. This can result in short sustain, even when the board will sustain much longer. A quick test: Without pedal, strike a single note and hold it, listening to the sustain for as long as it lasts. Then, hold the damper up off the string with one hand while plucking a string with the other. If the hammers are too hard, then they will drop off quickly in sustain, while the pluck test shows more sustain. You can try this test in various places in the scale.

BDB is correct in that we will want to "soften them underneath", we will want to deep needle the shoulders to make them more resilient. Then the hammer will become like a tennis ball that we are dropping on the pavement - it will rebound from the string very quickly. You will hear more sustain, and the tone becomes more full bodied with a better balance of partials.

I would have addressed the voicing issue with this piano by first doing a lot of needling. Some of the Renners need a lot of needling over repeated visits to come into their own. I hope the voicer did not juice the piano to the gills, that can cement the fibers together and make needling less successful. If the board is bad, then the doping is treating a symptom and not the underlying problem. Well voiced Renners should be able to get you there with the use of little to no doping.

If the board is bad, then you would be replacing the strings along with the board.

Jorge, I think the Imperial is one of the world's great pianos. But there is still more detective work to be done to find the root of your piano's problems.

Will Truitt

Will
Jorge started a thread about restoration and another about replacing the soundboard sometime ago but I do not know if any work has been done.

Jorge
This thread refers to the type of information you have in mind. Perhaps Olek will respond to a PM and provide you will some references.

Do pay attention to Ed Hall's first post in the thread rxd mentions.

PS My money would be on David's other factors. What does a pluck test tell you?

When the fundamental frequency of the notes nears, reaches and exceeds 3 digits in frequency-the weight of the hammer has tremendous influence on the power and sustain. (This is the 3 octaves of the top treble). Before using lacquer to make the tone project; the treble hammers should have the sides tapered, the width reduced slightly and the tails reduced to the minimum. This will reduce the inertia of the hammer and let it rebound from the string quicker which will reduce the damping of the string during striking without making the hammers harder. It also reduces the hammer "Knock" sound. It also increases the stability of tone and the durability of the hammers.

BDB does not have the physics correct regarding hammer string contact so disregard his posts on that topic.

Years ago I installed a set of new plain and wound strings on a Bosendorfer that the factory supplied. They worked very well but were much higher in cost than using Mapes strings would be.

Mr. McMorrow's physics is pretty sketchy, itself. Comparing how a heavy piece of concrete bounces with the way a tennis ball bounces is quite difficult, because you have to compensate for the difference in weight. If the tennis ball bounces 20 times higher than the concrete, yet the concrete weighs 50 times more than the tennis ball, which bounces higher?

But that is the problem with trying to get a lot of information about the properties of various piano parts. Doing the actual research is difficult. I have tried testing some of Mr. McMorrow's physics, and the results bore out some of his claims, but were not the results I want in a piano. All that you can do is read what everyone says, realize that they all may have a grain of truth to them, even contradictory ideas, and mix and match. It is really not something most amateurs want to do, or are even equipped to do.

Umm, That is contrary to everything I have heard, and also to more than a few physics explanations of hammer/string interaction I have heard. It is my understanding that the longer the hammer is in contact with the string, the more high partials are damped. The hammer that produces the least highs, i.e. the softest hammer, is doing so because of the greater dwell time in contact with the string. A rock hard hammer spends less time in contact with the string and allows more higher partials to be heard, at the expense of the lower frequencies. That is why hard hammers are louder, but have less carrying power, that more elastic ones.

I have also seen it demonstrated that a steel ball will bounce as high as a rubber ball if dropped on a steel anvil. The concrete analogy doesn't get it for me, as the elasticity of concrete is so low that there isn't correlation with something so much more elastic.
Regards,

Whoa! This thread is going on a tangent, away from what the point was. First of all, let's set the record straight, to the poster who told me to do my homework, you're assuming I didn't do that and that's simply not true. If you read my initial post, you'd catch that I searched and READ through several posts, not finding the information I was looking for. I've also read the books - Reblit's Piano Rebuilder's guide, A Guide to Piano Restringing from Travis and Pianos Inside Out in search for this information. I'm also not looking to be spoonfed,
I don't understand how comments like that are going to help me in any way, shape or form? And yes, I've posted before about my piano and I've been very truthful about my situation. My intention from the very beginning has been to restore the instrument, however, I was afraid that the restoration would change my piano's characteristics too much and in the end I'd be left with a completely "different" instrument,
or worse, an instrument that would hardly be recognizable as a Bosendorfer Imperial and I just want to enhance it from its current state or bring it back to its original capacity if possible. Now, I've had work done on it slowly, so that there's still a chance to back out if something goes "wrong", hence I started with replacing the hammers, which helped a little, so next it would be the strings. The soundboard has been thoroughly inspected and both the crown and the bearing are very satisfactory, which is why I am interested in replacing the strings. Now, the point of this thread is for me to get some information on physical properties of the strings and their terminology, I'm not trying to oversimplify or minimize anyone's profession. As an engineer, I tend to analyze things in a quantitative way, that's all. I know this forum is free and everyone here is basically donating their time and expertise but please don't just brush me off because you think I'm not worth your time, I can assure everyone I read all the information and consider everyone's opinion when they're offered in a constructive/productive way. Thank you again!

Jorge:

Have you contacted the music wire manufacturers for the specifications? Have you contacted Bosendorfer for their recommendations?

These sources would have more of what you are asking about than us blunderers here.

Voila! I could do that, except, what do I ask for? I can say: Give me specs, and they'll be like: What are you looking for? And I'll be like: Hhhmmm..... LOL!!!!

Jorge

Have you seen this? Please say what more you want to know.

According to what criteria does one choose the type of wire ?
The stress ?

This is THE determining criterion.

This criterion concerns the tone and the mechanical behavior of the string.
The tone : it is unanimously accepted that, in order to vibrate to its full potential (that is to say with a minimum of internal amortization as well as a good spectral balance), a string should be stressed at around 50 to 75 % of its practical breaking load (PBL), depending on the register (this notion is explained below). An under-stress (less than 45%) as well as an over-stress (more than 85%) gives bad sound results.

The mechanical behaviour : It is necessary to understand the following three notions:

The nominal breaking load (NBL): This value corresponds to the maximal tensile strength to which a steel wire can be subjected before it breaks. The results, obtained in laboratory conditions, extends from 1000 to 3000 Newton by mm², according to the diameter and the type of steel used.

The practical breaking load (PBL): The phenomenon of fatigue as well as the various bends, loops and twists applied to the wire weaken the performances of the strings once set in a piano. It makes it necessary to underestimate the results of nominal breaking load (NBL) by 15 % safety margin for Type 2, and 25 % for the other types. These values are given for every type and every diameter in a following table.

The elastic limit: apart from the ultimate phase called "break", a string put under tension goes through two phases:
- The elastic phase during which a stress of small intensity produces a stretch which disappears as soon as the tension is released.
- The plastic phase during which a stress of strong intensity produces a stretch which partially remains when the tension stops. We then have to deal with an irreversible deformation, the string does not hold tuning, becomes very inharmonic and ultimately breaks.

In order to respect the ideal stress rate of the metal, the frontier between the elastic phase and the plastic phase should never be exceeded. This border is named the elastic limit. It is situated at approximately 85% of the practical breaking load depending on the type of wire

The stress rate of a string thus depends not only on the resistance of the steel used but also on the length and diameter of the string and on the frequency at which it is tuned. To determine the ideal stress rate for every string you should know the characteristics of the steel used, the vibrating length of every string, its diameter and the pitch at which the instrument will be stabilized.

You are an engineer, right? Ask for what an engineer would ask for: metallurgy, tempering process, tensile strength, specific gravity, ductility, surface finish, corrosion resistance. I'm not an engineer, but these things come to mind. Or you could give them a call with the same questions you have for us. You might get someone that is delighted to talk about the intricacies of what they do and educate you in ways we just cannot.

Again, pluck the string with a guitar pick
Any big difference? If so and its in the direction you want then more voicing can possibly help. Also, another simple thing to try is find a tech that has spare hammers on the shanks of different types. Use it to strike the wire as close to strike point as possible. It may help you out.
You can have a tech replace a couple unisons with new wire in the upper registers. Samples always help.
No physics necessary.
Again, the imperial has lots of softer woods especially in the rim. Power from strings tends to bleed into it so it's not designed for Steinway like power-check your expectations.

Nice post, Ian, Gene..

To the best of my knowledge, restringing affects the sound of the piano the least of any variable (not including the bass section). Hundred year old plainwire can sound very good (unless very corroded).

Even though it seems off topic to you, Jorge, I agree with what the guys said above. They are trying to guide you away from this judgement.

It is very hard to say how any plainwire type will affect the sound of a given instrument until you install it. The interactions between hammer and board and string are so cohesive in producing the sound.

In that way, you will probably be frustrated out of an engineer's answer. Pianos are more complex than a standard piece of equipment where one component is replaced for a standard outcome. Even regulation can drastically change how a string sounds.

For that reason, I'd have a tech come in to look at your Imperial who really knows what he's doing (as in, builds his own complete custom instruments). To preserve the original sound completely, while molding the tone of certain sections, is really a tall order that only the best techs can fulfill.

That said, if you do restring anyway, I'd probably choose the Paulello wire for that particular piano.



Sorry Jorge, I didn't catch this. You definitely are looking for new bass strings. Together with voicing the hammer properly, you will get deep, vibrant sound. Do not lacquer the hammers.. you should be able to get all of this with new strings and good voicing.

You are looking for more fundamental and high frequency in your descriptions. High frequency is easily disrupted on the piano. Make sure the new bass strings are made by someone with rescaling capability. The wraps and the core must be swaged.. important detail that not all bass string makers do.

Small deposits of dust and corrosion are enough to kill the depth and power of bass strings. This has to do solely with high frequency.. you can see this on a transform, or spectrogram, and make the correlation with listening.

The treble issue could be caused by tuning alone (especially with the delicate treble of a Bosendorfer). If not, attention to the strike point is critical with new hammer installation. Make sure they aren't overstriking, and that the hammer mating is solid as well.

Additionally, you are looking for more hammer elasticity. This is what builds the tone you are talking about. You need a very experienced voicer to build this into your new hammers, because it requires several days of work and listening over time.



One last thing.. this is an honest word to you about future work. You cannot get great results by doing things piecemeal on any instrument. This is destructive and will result in a patchwork piano, full of many unseen errors. A single technician must see this through from beginning to end to achieve great tone on your piano again.

A piano is sculpted and brought to life with extremely delicate balance. You will always get mediocre results with something 'installed' or done with limited scope. The decisions involved are just too complex and involve a lot of understanding.