Jelco 750 query

[Tea24]

The other day, on lifting the stylus from a record my Jelco 750 suddenly banged down into the mounting hole. Obviously I hadn’t tightened the collar enough. (I always try not to over tighten – just as much as necessary).

Getting the VTA right on this arm is a bxxxxy nightmare; on my TT I have restricted room to manoeuvre & I cannot really see to put the hex wrench properly into the socket. I think I shall have to disconnect everything and move the TT elsewhere and then re-connect everything. A right PITA.

I wish someone would make an arm with a geared VTA adjustment with markins so that one only has to screw it up & down; it must have removable head-shells too.

Well after three quarters of an hour I got there BUT, on checking the weight for VTF I notice that the stylus now goes down & then suddenly takes a swipe towards the centre of the disc. Not much, you understand, (a few mm) but I don’t think it would be very good for the stylus.

Have I somehow damaged the arm or is there another explanation? It has never done this before.

(I suppose it could be the azimuth – it doesn’t look quite right).

Any ideas gratefully received.





.

[struth]

maybe the anti skate needs readjusting.

[Tea24]

Good Point; I hadn't thought of that. I will check (tomorrow - I am busy listening to Donizettion my Notts Analog at the moment. Anyway its been a stressful day!)

[Spectral Morn]

Yep Julian its a rubbish securing collar. I would suggest getting one of Ammonite Acoustics much better quality Jelco mounting collars. http://theartofsound.net/forum/forumdisplay.php?55-Ammonite-Acoustics

Many companies do make exactly that type of VTA adjustment, but its the higher end companies like Graham, Triplannar and others that build arms with easily adjustable up and down calibration in their designs.

[Tea24]

It's a big pity as it's a great tonearm! I had thought about a new collar & I think I'll go that route in due course.

[Scooby]

Have a look at these:

http://www.vtaf.com/vtafadaptations.html

Ive only used the Rega version but it was wonderful.

[Ammonite Audio]

As Neil has pointed out, you have just discovered why Jelco's standard collar is so poorly designed. The arm pillar tends to fall over as the grub screw is tightened, which is why you see the arm drifting across, and why azimuth appears to be incorrect. My improved collars deal with this issue totally, and make VTA adjustments smooth, easy and repeatable. I do have a few ex-display (but pretty much unmarked) collars available, so if you want to address the problem and can't quite run to a new one, I can give you a good price on one of these.

I have been asked in the past to do a VTA on the fly collar for the Jelco arms, but this would be complicated and really rather expensive, so it's not something that I feel would be commercially viable.



The other day, on lifting the stylus from a record my Jelco 750 suddenly banged down into the mounting hole. Obviously I hadn’t tightened the collar enough. (I always try not to over tighten – just as much as necessary).

Getting the VTA right on this arm is a bxxxxy nightmare; on my TT I have restricted room to manoeuvre & I cannot really see to put the hex wrench properly into the socket. I think I shall have to disconnect everything and move the TT elsewhere and then re-connect everything. A right PITA.

I wish someone would make an arm with a geared VTA adjustment with markins so that one only has to screw it up & down; it must have removable head-shells too.

Well after three quarters of an hour I got there BUT, on checking the weight for VTF I notice that the stylus now goes down & then suddenly takes a swipe towards the centre of the disc. Not much, you understand, (a few mm) but I don’t think it would be very good for the stylus.

Have I somehow damaged the arm or is there another explanation? It has never done this before.

(I suppose it could be the azimuth – it doesn’t look quite right).

Any ideas gratefully received.





.

[Tea24]

Thanks for all the replies.

Hugo I will go to your site & order one; thanks for the offer, but I think somebody else in harder circumstances than my self should benefit. I assume it is a drop in replacement for the Jelco collar?

Julian

[Tea24]

I have been looking at my set up; Jelco 750 on Lenco GL75. The Lenco metal base plate has been cut off on one corner so the Jelco is mounted directly onto the wood of the heavy Layers of Beauty plinth, so the surface of the plinth is lower than the Lenco metal base plate by about 10mm & there seems to be less than 5mm between the top of the Jelco collar & the base of the arm rest plate, so I fear this might not work for me.

I already have some spacers in some of my headshells, so it might be difficult to put in more. Would a thicker platter mat than the Lenco original, or placing another underneath that change the sound?

[Ammonite Audio]

Thanks for all the replies.

Hugo I will go to your site & order one; thanks for the offer, but I think somebody else in harder circumstances than my self should benefit. I assume it is a drop in replacement for the Jelco collar?

Julian

Sorry - I've only just seen your post. Yes, it is a drop-in replacement for the standard Jelco collar. It is 4mm taller above the armboard than the original, and longer underneath, but the mounting arrangements are identical.

[cuddles]

Can you point me to the correct size stubby Allan key for the collar. It's a bit tight using a standard size.

[Ammonite Audio]

Can you point me to the correct size stubby Allan key for the collar. It's a bit tight using a standard size.

Are you referring to an original Jelco collar, or my improved version? My collar has an M6 grub screw that uses a 3mm allen key. I'd have to open up a new Jelco box to measure the size of an original allen key, but I suspect it's 2mm.

[cuddles]

Thanks Hugo - 3mm it is then ;)