Tracking Alignment Adaptor for the Exhibition Soundbox

[Curt A]

I always thought that a custom angled isolator/rubber flange for the back of an Exhibition reproducer might work, without making a metal adaptor... or the brass collar could be cast in the rubber of the flange at an angle. Has anyone tried something like this? It seems that this would eliminate the problem of added length to the tonearm...

For Victor machines, I also thought of having a custom "gooseneck" made from brass tubing and bent to the correct angle... I had some trouble locating the correct size of brass tubing or I would have tried it. Does anyone know of a source for the correct size tubing?

[Marco Gilardetti]

[Marco Gilardetti]

For Victor machines, I also thought of having a custom "gooseneck" made from brass tubing and bent to the correct angle... I had some trouble locating the correct size of brass tubing or I would have tried it. Does anyone know of a source for the correct size tubing?

I have sometimes seen machines in which the gooseneck was reworked in order to have the Exhibition soundbox reach the record at an angle, but for one reason or another if I search for them with google images I get only pictures of Hi-Fi garbage. Other people crafted collars that would alter the angle, but these are usually awful to be seen.

However, considered the florid market of reproduction spare parts for the Exhibition, I am surprised that no one has yet deployed a replacement gooseneck as described above that would improve the tracking error.
If a gooseneck that would not alter significantly the look of the gramophone would be for sale, I would most probably buy it.

[audioengr]

Actually, if you have the luxury of redesigning the tonearm, you should be able to do much better than this. The needle and reproducer should be in-line with the pivot-point, not offset. It should be a straight tonearm. You can do this analytically and come up with the exact solution that puts the needle straight with the grooves from start to finish on a record. I believe you can find a solution that puts the pivot point straight behind the current pivot-point, so that the horn weight is properly supported.

[jamiegramo]

I don't get what they meant with "lifebelt", however it looks as if this gizmo was made in order to enhance soundbox-to-tenarm isolation. As it is mounted on springs, which seem to be adjustable to some degree, perhaps it may help to improve the tracking error a bit, but I would say that this wasn't the primary task for which the device was made. It also looks pretty heavy and will most probably greatly raise the tracking force over the record.

It's evidently had the back of an Orchorsol soundbox grafted onto it. This page of the late Graham Barber's website has good photos and an explanation of the lifebelt: http://www.graham-ophones.co.uk/orchors ... 4594029474

It's a fascinating combination and I'd very much like to hear how it sounds, but it's extremely expensive for a "Frankenbox"!

Marco and Andy thanks for taking the time to reply. I agree the device might add too much tracking weight to the exhibition soundbox (which is heavy anyway) but maybe fine with the correct Orcholsol soundbox which appears lighter. It does not appear to be specifically designed for altering tracking alignment by any great degree.

The seller also sells the Orcholsol rubber Lifebelt for this and shows a similar attachment on the back of the Orcholsol soundbox, shown below. I've only previously seen the Orcholsol soundbox from the front but I see the late Mr Barber does clearly show it complete with a rather perished Lifebelt.

Marco, I assume the term 'Lifebelt' is saying that by using a piece of compliant isolating rubber tube between tonearm and soundbox it will save the life of records?

[jamiegramo]

This is a cool adapter, but I think I have another equally effective method. If one changes the location of the pivot-point of the tonearm, it will accomplish the same thing. See the analysis below:

Original alignment

Needle-tracking-analysis-orig..pdf

Offset alignment

Needle-tracking-analysis.pdf

I have a suspicion that this is why they put the "bustle" on the back of the VictorII. To move the tonearm pivot point back. I will try to add a spacer to the mount of the tonearm assembly. I should be able to get at least .25", maybe more.

Please give it a go and measure the tracking error at the 3 different points and report back. Would not the needle fall too far short of the spindle?

[jamiegramo]

I always thought that a custom angled isolator/rubber flange for the back of an Exhibition reproducer might work, without making a metal adaptor... or the brass collar could be cast in the rubber of the flange at an angle. Has anyone tried something like this? It seems that this would eliminate the problem of added length to the tonearm...

For Victor machines, I also thought of having a custom "gooseneck" made from brass tubing and bent to the correct angle... I had some trouble locating the correct size of brass tubing or I would have tried it. Does anyone know of a source for the correct size tubing?

This does work very well. Although as the angled flange tilts the reproducer forward into the correct alignment this creates too much overlap, around 16mm as opposed to the 8mm recommended by EMG for the length of tonearm and offset achieved. Even so, this still improves the sound and record wear and I don't find the angled flange is noticeably worse than my brass adaptor that does achieve ideal overlap.

What is noticeably worse is playing the machine at its original alignment!

[audioengr]

This is a cool adapter, but I think I have another equally effective method. If one changes the location of the pivot-point of the tonearm, it will accomplish the same thing. See the analysis below:

Original alignment

Needle-tracking-analysis-orig..pdf

Offset alignment

Needle-tracking-analysis.pdf

I have a suspicion that this is why they put the "bustle" on the back of the VictorII. To move the tonearm pivot point back. I will try to add a spacer to the mount of the tonearm assembly. I should be able to get at least .25", maybe more.

Please give it a go and measure the tracking error at the 3 different points and report back. Would not the needle fall too far short of the spindle?

The analysis shows that it will be fine. I took a one-sided record and flipped it to the blank side and scored the original tracking with the needle and scribed the new tracking. Now I just need to add the spacer to the tonearm assembly.

One reason that I want to do it this way is I am also using a Victor 4 reproducer with great results and it is too large to do much angling with.

[audioengr]

I changed to Victrola 4 reproducer and this gave me an other ¼ in length. Also a little more offset.

New analysis shows that .8" offset of the arm pivot will achieve 12 degrees error at the start and 15 degrees at the finish of the track. See attached.

Needle-tracking-analysis-Vict..pdf

(18.37 KiB) Downloaded 86 times

[audioengr]

Below is the photo of the new bustle attached to the existing bustle that relocates the tone-arm pivot back .75". Tracks very nicely now.

IMG_7399.JPG (130.73 KiB) Viewed 1507 times

I decided to calculate the length of a tone-arm that would achieve perfect tracking across the 10" record. See the link below:

Zero tracking error analysis.pdf

(7.58 KiB) Downloaded 96 times

39 inches is a bit long. This is why most modern turntables have a hinged tonearm.