Does anyone have any tips regarding reducing excessive false beats in the capo d'astro area of some grand pianos? It seems to happen most often with certain models of pianos, more than others. The false beats are not only annoying, but also hard to get a clean unison, and all the fidgeting makes rendering the string for a stable tuning difficult.
String leveling, hammer fitting or CA glue on the bridge pins don't seem to do the trick in this case, for me at least. Has anyone had success with lowering string tension and lightly sanding the underside of the capo d'astro to remove the string grooves? Obviously, this is too time consuming for a standard tuning and not stable enough for just before a concert, so are there other simpler tricks, pre-concert that anyone has found helpful? Would a lubricant like Prolube at the contact point with the strings at the underside of the capo d'astro be safe and effective?
Resurface capo and consider case hardening if too soft. Restring.
You could try a Sraight-Mate
David's suggestion has become my go-to protocol: https://my.ptg.org/communities/community-home/digestviewer/viewthread?GroupId=43&MID=639373&CommunityKey=6265a40b-9fd2-4152-a628-bd7c7d770cbf&tab=digestviewer
Thanks, but the link times out and won't open...
The reason this situation comes about in the first place is that since they are paid piece work in the factory, there is an incentive to spend 5 minutes shaping the V-bar rather than 30-60 minutes to get it right. It does not cause tonal issues right out of the gate, but rather several years down the road (out of warranty) as the strings naturally start burying themselves into the metal.
As Ed McMorrow has long espoused, they will do this whether the V-bar is "round" or "sharp", but when round there is far more surface area for the strings to vibrate against vs a true V profile. In fact they will produce the grooves but then they stop at a particular point BEFORE becoming a problem (I'm generalizing here).
If you can produce visual proof of the situation to the owner (cell phone camera is great for this) and describe the how and why of it, then you simply tell them the ONLY way to improve this problem is to do as described by Ed M. or David L. As hard as it is to swallow, that's what's involved. The visual is more powerful than just talking about it. It's hard work but the results will pay off.
If though the problem is due to waving bridge pins, that's a different story altogether.
Peter Grey Piano Doctor
I only understood myself to have posted a single link. In any case, you can search for the post using the search term "situ" in the site's search box. Result will be in the top 5.
I'm sure the protocol is very worthwhile, but as I'm not a rebuilder, I can't see myself ever going to that extent for this issue. I wonder if anyone has tried taking down the tension in the area slightly, and moving the strings one string width to the right, or just enough to get them out of the grooves, re-tensioning the strings, re-spacing and re-fitting the hammers to the strings? (Assuming the dampers are newer and would conform to the new string position.) They would eventually create new grooves in the v-bar, but it might give 10 or 20 years of improved tone....?
Carl Radford went:
I'm sure the protocol is very worthwhile, but as I'm not a rebuilder, I can't see myself ever going to that extent for this issue.
False beats sure are an annoyance, and I've always figured that if there were a simple and remediable cause for them we'd all know about it (including piano factories). And we wouldn't be having this conversation.
It's not clear why this is a pressing issue. Of course, nobody likes to tune through them (and ETDs are oblivious to them). But is the piano owner complaining about them? Do you want to bring up them with the owner to avert a complaint about how "clean" your unisons are? I've always just kept quiet about them until asked, and when an description of David's protocol will convince the owner to live with them. (And of course, the first thing you can try is driving any bridge pins which have wiggled their way upwards, down to their original depth.)
I have a 20+ yr old Boston in my patient file that NEEDS this operation badly. When I took the pics to show the client the condition it was obvious that a previous tech had performed the "move the groove" dance in this area. The impressions were deep and the problem was back. Her eyes widened as she saw the mess.
I'm not a fan of doing this in place...but maybe. The whole thing SHOULD be restrung as she's a heavy operator. But by the hour, the bill will be what the bill will be. I didn't create the problem, but I know how to cure it.
Back in about 2019 I had a client with a persistent string breakage problem on his Kawai RX-2. I restrung the treble using Paulello XM wire, and while I was at it, reshaped the v-bar using David's protocol. I did the whole job on site, and billed 5 hours of labor. Maybe I spent a little more time than that, but maybe not. I don't remember for sure. In any case, the client was pleased with the result.
You are a MONSTER to do all that in 5 hours. Incredible!
It may simply be a matter of my having handled my billing generously. I was on very good terms with this customer, and may well have given him a break by underbilling the number of hours. But the only record of time I have is the invoice.
In consider my hourly rate to be high enough that I can get away with this sort of thing without hurting myself.