Looking for a rod-shortening compensator

Georg Sørtun · From: Mandal, Agder, Norway

I need to make pedal 1 and 3 pull string 5 and 10 slightly higher when I lower string 3 and 6 a full tone with RKR. The only way I have found for achieving this is to shorten the rod for pedal 1 and 3 - there's actually only one rod that must be shortened.

Anyone know of a rod-shortening, tunable, compensator?

Bent Romnes · From: London,Ontario, Canada

Bumping this to the top to get some action and to ask:
Georg, I don't know much about compensators - yet.

However, what you describe is that what you would call a run-of-the-mill compensator or is it something special?
Hey you might already have got your answer so I'll butt out for now Smile

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Georg Sørtun · From: Mandal, Agder, Norway

Bent, I have gone through all possible solutions using regular rod arrangements to tune/compensate via the changer - including all I could find on this forum. None will solve this "raise a pedal-pull slightly further when a lever is pushed" case on my Dekley.

I have a working compensator in place now, but it is an awkward solution in that I actually bend the horizontal rod coming from (both) P1 and P3 slightly with an arm connected to the RKR pull-arm shaft, so a raised string 5 to C# gets tuned from 275Hz to 278Hz when RKR is activated. This "bend-arm" isn't tunable and there's some friction involved causing potential detuning if I don't activate and release pedals and levers in perfect sequence, so I'm looking for a replacement.

Have drawn up a compensator that will work as intended (once I get a few parts from Nils F.), but before building such a compensator from scratch (again) I wanted to check if rod-shortening, tunable, compensators existed, that I could either get hold of or at least check my own solution/drawing up against. Don't want to reinvent the wheel, unless I have to Smile

I don't use, or need, many compensators on my Dekley, apart from this one. ATM I only have one (rod) to tune string 1 (F#) sharp for certain pedal/lever combinations.

My set-up is rather unusual though, and requires plenty of regular pull rods. Thus the space near, and at, the changer is already pretty full, and I rather not put in more rods there than I have to even if I could compensate that way.

Georg Sørtun · From: Mandal, Agder, Norway

So, how on earth do you all adjust the actual pull of one pedal on the fly when another pedal/lever is activated and the resulting chord comes out sour?
Or are there no pedal/lever combination that makes such an adjustment necessary on your steels?

Bar slants/push works for me in some cases but not in all, and, as mentioned; I don want to reinvent the wheel - only keep my chords naturally clean and untempered.

Bent Romnes · From: London,Ontario, Canada

Ok Georg, I'll bite. I have made a fool of myself before and I don't mind doing it again, all in the name of learning.
I don't know what the heck you are talking about here. Looks like nobody else does either Smile

First: what do you mean by adjusting the actual pull of one pedal "on the fly"? Do you mean adjusting the throw of the pedal while playing?

The normal adjustments we have are:shortening or lengthening the pedal rod at the ball and socket joint.
Then you have the pedal crank stop. It has an adjustable screw on it that goes against a stop.
The same goes for knee levers. They also have adjustable stops and some guitars also have adjustment on the pedal angle itself.

Trying my best to decipher what you are asking here. I think it sounds more like what you are after is a compensator. I don't know enough about these to give you an intelligent explanation but I am sure there are someone here that can help you.
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Georg Sørtun · From: Mandal, Agder, Norway

Norwenglish has its shortcomings, I know Winking

Believe me; it doesn't come through all that much clearer in Norwegian.

More strings involved, but for simplicity let's focus on only two strings:

1: Pedal 1 down lifts string 5 from B to C# - frequency: 275Hz at C#.
2: Lever RKL lowers string 6 from G# to F# - frequency: 185.4Hz at F#.

When RKL lowers (2), Pedal 1 (1) should, ideally, give me a frequency of 278Hz for C#, 3Hz higher than if RKL isn't lowering, to get that perfect, beat-free C# and F# chord on string 5 and 6 with P1 and RKL fully engaged.

I know I can shorten the horizontal pull rod to lift C# 3Hz higher, as described, by cutting the rod and reconnect its ends close together in rotating couplings at one end of a lever-shaped plate. This is is what will happen then:

a: Pedal 1 down will put force on this connection and make the rod-ends line up, and I can tune C# to the normal 275Hz.
b: If I push the other end, the arm, of the lever-shaped plate either way, the rod-ends pulling string 5 can't line up no matter the force, so the rod will in effect become shorter. The push on the level-arm can be establish by a short rod connected to RKL, and by regulating the push on the lever-arm, I can tune for 3Hz lift of C# - to 278Hz when RKL brings G# fully down to F#.
c: When P1 is not engaged, such a lever-connection is "hanging loose". Thus it won't cause any detuning if/when its arm gets pushed around a bit.

So far so good, but I see no point in constructing such a lever-based coupling if something already exists to the same effect. So that's why I'm trying to explain what I want, in the hope that someone has seen, heard of or actually use, such a rod-shortening compensator.

Bent Romnes · From: London,Ontario, Canada

Georg, I see you are up and running on here anyway. Hope you get your PC woes fixed asap.

This is way over my head but I seem to detect the need for a regular compensator. This 'rod shortening' business sounds exactly like what some steels have installed on I think the 1 string in particular. When ped's A&B are activated, the 1st string drops and needs to be pulled up ever so slightly. This is what the compensator does.
I have been looking for a sketch..I have seen it on the forum earlier. I just cant locate it. Could be the Carter web site, check there.
I'll also send you another email.
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Georg Sørtun · From: Mandal, Agder, Norway

Bent, my PC problem doesn't prevent me from communicating, although it does slow down my web-access too. Only one out of 7 computers available on my internal network at the moment, which means I can't easily transfer images or files, or create drawings that might make a few things easier to explain. Some software/files are on the "wrong" computers, so for a few more days I've only got access to what's already on my main computer.

The regular compensator on string 1 - which I have already - is there to re-tune that string to exact frequency in the relevant natural scale when we change key by activating certain pedals. String 1 is corrected while in its rest-position, so tuning it to exact frequency in any key by adding one or more pull-rods, is easy enough.

If a string changes frequency because other strings are raised or lowered, we're talking detuning caused by body-drop in one form or another. My Dekley doesn't have body-drop or detectable, unwanted, detuning thanks to the somewhat unusual modification - the free-floating neck that holds the bridge/changer in mid air, so detuning is not part of the problem.

What is causing the need to re-tune 5th string with pedal 1 pushed down, is the key-change that takes place when I lower string 6 (and string 3 and 7 - all on the same note one octave apart) one whole note with RKL. The C# on string 5 doesn't suffer from detuning, it simply is to low for natural chords in the new key - 3Hz too low. A 3Hz beat doesn't sound good, and should be brought down to 0.5 or lower where it is easy to cancel out with the bar.

We re-tune/compensate on string 1 for certain key-changes for exactly the same reason - to get perfectly natural chords. However, rising only raised strings further to meet the key-change is slightly more complicated.

If I were to use normal compensation I'd have to to lower string 5 3Hz in all open and pedal/lever combinations except this one. Certainly possible, but far more complicated and difficult to rod up and tune in in an old instrument that doesn't have any form for split-tuning.
I am not ready to modify the entire changer-functionality yet. That will have to wait until I find a good reason to build a steel from scratch, which will probably have the changer at the key-end anyway so I can fine-tune the bridge for the tone.

Anyway, if such a compensator isn't ready made for older instruments, or because no-one else needs one, then I'll just have to make my own. Some GFI parts will fit right in there, so I only have to get the parts, shape a piece of metal and drill a few holes.
Thanks very much for helping out.

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