Exhibition screws adjustment

[Inigo]

Just seen this in a colleague's Exhibition for sale... And my question is, shouldn't the nuts (these are knurled nuts in this early model) on the balance springs adjustable screws, be tightened against the fix screw holes in the body legs? In these photos they seem to be screwed the opposite, against the needlebar base plate instead, thus fixing the spring ends against it. I always believed the nuts were for securing the screws in position, and the spring ends should be left "free", only tensioned by the screw heads...
I mean, in the photos, the gap shouldn't be at the other side of the nut, between it and the screw heads?

[alang]

You are correct, at least this is my understanding as well. The nuts are there to fix the screw in place, not the springs.

Andreas

[Inigo]

Thanks for confirmation. For a moment I suspected that this adjustment was what I needed to do mine work better... .
I always felt that the hard balance springs were subject of improvement... I didn't touch them, but introduced tiny soft rubber washers in between, and relaxed the tight gasket pressure on the diaphragm edge, and I got a perfect adjustment for playing electrical records. But I didn't like the muffled sound obtained when playing acoustical records, so I reverted all the changes and came back to the outright adjustment. Nevertheless, I'd like to get rid of that ringing tone in the treble, which I find unpleasant. I've noticed, though, great differences in sound between different records. For instance, spanning acoustic Odeón recordings tend to sound shrill and very high, with little bass. Others, though, shuns well. Perhaps I'm blaming on my exhibition adjustment and actually there is the fault of the recordings, that are tinny. I've lately come to think that the best is to locate a good full sounding acoustic record, kind of those good acoustic Harmony records, and attach to it for the adjustment, until I get a good sound of it. Then simply play the records and discard those which sound bad and unpleasant.
Nevertheless, the short internal horn of the machine (a big hornless hmv, similar to the Victrola VI) had something to do on it. On the orthophonic machines, almost all of the records sound much better, and there's no trace of that fastidious ringing tone, so the fault is also on the unmatching of the short horn and the Exhibition adjustment. I've been obsessed about adjusting the balance springs at the minimum pressure that kills the blasting, and maybe this is not the right adjustment. The shootings have also a damping role, and maybe a tighter spring pressure is more desirable... Still I have to do more tests with this soundbox.

[AZ*]

You are both correct. The definitive source which confirms the role of these lock nuts are the "Instructions for the Repairing of the Victor Exhibition Sound Box." These instructions are contained in the appendices of Baumbach's LFTD. I have seen reprints of these instructions for sale, and they are shown at the following link which includes pictures and tool references not shown in LFTD:

https://grammophon-platten.de/page.php?490

[Dischoard]

At least you didn't do like I did and chase around a strange distortion sound for half an hour only to find that you neglected to tighten one of these nuts and it was freely vibrating making it sound like Nat Shilkret's Orchestra had all plugged their instruments into distortion pedals...

[Inigo]

it's true that when you examine the soundbox and watch that the screws alone are not really fixed, soon you understand that the role of the nuts is to fix the screws firmly in position, and to maintain the delicate spring adjustment. With these hard leaf springs, a quarter of a turn changes the sound drastically. ..!
I also have one of those exhibition junior soundboxes with the press ring closure. The needlebar balancing system is the same of a standard exhibition. My leaf springs were broken, so I removed them and then made two new springs a bit different. I made twin U steel wire springs with an O eyelet to fix them around the screws, and mounted them as in the two spring EMG/Expert (?) soundbox, with the free end of the U wire placed on top of the needlebar plate so to press it against the knife edges, and it works fine! Someday I have to buy new leaf springs and revert it to its original shape.