Jelco 250st vs Jelco sa 250-S tonearm

[billyz]

I know the Jelco 250st is straight and a non-removable headshell, and the SA 250-S is curved with a  removable headshell. Is there any problems to using the SA 250-S with the Lenco L75 ? Is the removable headshell a real negative in terms of performance ? Is there any inherent advantage to the Straight tonearm?  I kind of like the idea of being able to have a few different cartridges loaded up in multiple headshells.

 Billy Z

[willbewill]

Hi Billy Z and welcome to the heaven

I doubt you would notice much difference between the two Jelco arms, the geometry is slightly different for each of them but at most only a few mm so shouldn't affect much.

[billyz]

I just measured the Jelco/Audioquest pt6 tonearm pillar. It measures 45/64" or roughly 17.859 mm. Pretty close to the Jelco stated diameter of 18mm. The Linn Ittock measures 63/64" or just shy of Linns stated diameter of 25mm. The  Lenco inside diameter of the mounting collar measured 1.025" or 26mm.  So to use the Jelco arm I will need to have an adapter bushing made or a whole new mounting collar to fit the Lenco chassis.

 I bring this up as there is alot of info out there that states the Jelco is a drop in replacement, it is not. The effective length is proper though.

 Any thoughts on what to use Brass or Aluminum ?

[04rdking]

You can try the 35mm film canister trick as seen here.

http://www.lencoheaven.net/forum/index.php?topic=3970.0

[billyz]

 I think the film can trick works if you have a linn arm only, it is 25mm and the lenco is 26mm, the Jelco is 18mm , too small for just a film can to shim.

 I am going to a machine shop and see if they will make me one for a reasonable cost. Aluminum or Brass.

[skippingjack]

When I (briefly) used one of these arms with the lenco top plate I used then original lenco mounting collar with no extra sleeve.

I used a set of stainless steel bolts and turned them with enough force that the screw threads for vta adjustment on the original sleeve gave a little bit. This meant that the original grub screws would go in a little bit further so I could mount the jelco arm without using a sleeve.

[Paul]

The one advantage of making up an adapter bushing is that you can offset the inner hole. Then by rotating the bushing you can get small adjustments in pivot to spindle length.

[billyz]

 I have a local machine shop making me a bushing  out of Aluminum. same outside dimensions as the original lenco arm. with socket head allen grub screw. The lenco arm is 3/1000's under the inside diameter of the collar. Same for the inside dimension we are going 3/1000 over the diameter of the Jelco/Audioquest pt6.

 I may have figured out how to use the Lenco arm lift too. I removed the hydraulic lift cylinder from the Jelco. Looks like the Lenco will just make it.

[taskerc]

If you are serious about a Jelco, look for an LAD arm on eBay.  A seller from Mauritius has been selling them at about $100 USD plus shipping and they are VERY NICE.  It is basically a Jelco 370AH in a shorter arm geometry that seems identical to 750D AND the 250 S shaped arm you are looking at.

I has the additional feature of the damping trough and is a really great arm.  And exceptional value without a doubt.

Chris

[billyz]

If you are serious about a Jelco, look for an LAD arm on eBay.  A seller from Mauritius has been selling them at about $100 USD plus shipping and they are VERY NICE.  It is basically a Jelco 370AH in a shorter arm geometry that seems identical to 750D AND the 250 S shaped arm you are looking at.

I has the additional feature of the damping trough and is a really great arm.  And exceptional value without a doubt.

Chris

 I will check it out, thanks!

[taskerc]

I don't see him with any on there at this time but he regularly does have them for sale - and they really are GREAT value since it does not say Jelco on the listing anywhere.  It was an OEM specific variant made by Jelco for LAD and is, as mentioned, based on the (also OEM) 370AH.

It was funny.  I had a 370 (and a custom alignment protractor) and found the LAD arm and tried to fit it and COULD NOT get the geometry right.  I did not notice that, despite looking identical, that the dimensions were different - specifically the tonearm length.  So I finally broke down and emailed Jelco, not expecting anything.  But they came back telling me about the LAD arm and sent me a PDF with the dimensions etc.  And as it turns out, it was dimensionally identical to the 750 series.  So once I used those dimension parameters, alignment was a doodle

So if you get the LAD arm, PM me and I will send you the dimensions document.

Regards, Chris

[billyz]

I don't see him with any on there at this time but he regularly does have them for sale - and they really are GREAT value since it does not say Jelco on the listing anywhere.  It was an OEM specific variant made by Jelco for LAD and is, as mentioned, based on the (also OEM) 370AH.

It was funny.  I had a 370 (and a custom alignment protractor) and found the LAD arm and tried to fit it and COULD NOT get the geometry right.  I did not notice that, despite looking identical, that the dimensions were different - specifically the tonearm length.  So I finally broke down and emailed Jelco, not expecting anything.  But they came back telling me about the LAD arm and sent me a PDF with the dimensions etc.  And as it turns out, it was dimensionally identical to the 750 series.  So once I used those dimension parameters, alignment was a doodle

So if you get the LAD arm, PM me and I will send you the dimensions document.

Regards, Chris

 Yes, I noticed he is not listed in the completed auctions either.  I like the idea of keeping the geometry the same as the stock Lenco and using the stock lenco collar.
 I already have a machine shop boring out an Aluminum bushing adaptor for the Audioquest pt6 I have. So I will use that for now, and keep an eye out fothe LAD tonearm.

Z

[billyz]

I got the Aluminum bushing back from the machine shop. Had a 5mm allen screw put in too.  I had to grind down the Allen screw a bit but it is working great. I found out the Jelco pillar is not uniform either. Had to sand it a bit for the bushing to slide all the way up. We must have measured it nearer the bottom as it starts on fine but gets tight as it goes up. No problem though.  I will post some pics as son as I figure out how to host them.

[ian]

Hi Billy,
There are some instructions for including pictures here http://www.lencoheaven.net/forum/index.php?topic=143.0.  Personally I now use photobucket, Just follow the instructions there to upload you picture then copy the tag labelled IMG code into your post here - job done!  Keep your images below 800 pixels wide and use a bit of compression to speed up the display.

Cheers, Ian

[billyz]

 Finally got some pics of the bushing adapter for the Jelco tonearm to Lenco collar.

 You can see I had to sand the pillar to get the bushing to slide up.