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12" tonearm vs 9" tonearm. Is longer always better????

Onebean

Onebean

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I picked up a Lenco L75 recently, and I'm planning a plinth build for it. I'd like to set it up for 2 arms, for future flexibility. I'm currently looking at Jelco 750 arms, and considering trying a 12" version. Is a 12" long arm always better than it's shorter sibling? Are there any drawbacks to a 12" arm, other than the extra space requirement? My plan is to design the plinth with interchangeable arm boards, so I can run any arm in a 9"-14" range. I'd like to experiment with some DIY Uni-Pivot arms at some point down the road, but for now I'd like to focus on purchased arms, and the 12" Jelco 750 seems like a good deal. Let me know what you think.

Onebean
 
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Onebean said:
I picked up a Lenco L75 recently, and I'm planning a plinth build for it. I'd like to set it up for 2 arms, for future flexibility. I'm currently looking at Jelco 750 arms, and considering trying a 12" version. Is a 12" long arm always better than it's shorter sibling? Are there any drawbacks to a 12" arm, other than the extra space requirement? My plan is to design the plinth with interchangeable arm boards, so I can run any arm in a 9"-14" range. I'd like to experiment with some DIY Uni-Pivot arms at some point down the road, but for now I'd like to focus on purchased arms, and the 12" Jelco 750 seems like a good deal. Let me know what you think.

Onebean
Click to expand...

Why do You consider 12" better?
 
12" tonearm vs 9" tonearm. Is longer always better????
Click to expand...

No. Gotta watch your tradeoffs. Longer is heavier and that means less able to handle all those old MM cartridges of very high compliance.
But you have lower tracking error numbers. Get what you need and enjoy.
 
I have a Sony PUA-286 tonearm on a table of mine, and it is a little heavy as far as effective mass goes. Just have to use a lower compliance cartridge. I don't notice any difference in tracking ability or groove distortion versus my 9" arms, but the 12" arms sure are impressive looking.
 
gusten said:
Why do You consider 12" better?
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I don't consider them better, I have no real knowledge or experience with the differences. Looking at the Jelco 9" and 12" arms, the price difference isn't that much. If the 12" is better, I'll lean towards it, if there are compliance issues, I'll stick with a 9".

The cartridge I plan to use is a Denon 103. I have read that the Jelco 750D is a good match for the Denon. I don't know if the same is true for the 12" version.

Onebean
 
The DL-103 is low compliance and likes a higher mass arm, so the SA-750L should be a good match. But, it can also work well with the 750D with a heavier headshell and the "heavy" Jelco counterweight.

So, in some ways it's six of one and a half-dozen of the other. Personally, I'd go with the shorter arm as it provides more flexibility IMO.
 
The effective mass of the 12" SA-750L is less than the shorter SA-750D:



Personally, I think the SA-750L is as fine as frog's fur. Definitely not as versatile, however, in terms of tables it will fit on...
 
sqlsavior, can you help me understand which arm in the chart is optimum for the Denon 103, and which arm is optimum for a wide range of cartridges? I haven't listened to my Denon 103 yet, so I don't want to buy a white elephant tonearm that won't work good with other cartridges. I also have a Dynavector 20X, and an Ortofon MC20MKii that I would like to have the option of running on this arm. Thanks for the help.

Onebean
 
Advantage of the longer arm is reduced angular offset, leading to lower tracing error, skating and other tracking issues. Disadvantage is the wand is less rigid for a given material, leading to added harmonic colouration.

Pick your poison....
 
Build your plinth to be as flexible as possible in regards to future arm mounting sizes, thats if space permits.
Things will quickly get oversize when building for more than 2 arm sizes and even larger for 3 unless
you go for the outboard pivoting types or a combination style.

I found that a separate 9" mount and a 12" to 10/10.5 " combination armboard
gives good flexibility, Splitting the larger combination armboard really made the size unmanageable
especially if doing CLD and the mass thing.

I actually only feel comfortable going up or down a flight of stairs with someone helping since the
an accident would be catastrophic.
 
Onebean said:
Totem, do you have any pictures of your plinth you can share?
Click to expand...

The first pic shows a 9" arm and the other split 12" -10.5 /10 armboards.
The split armboard can be changed for a 1 piece as there were half a dozen spare armboards made for a variety of
possibilities.

The arm cutouts are a labyrinth style where you have varying opening size's as you
go down versus a large hole.

IMG_3227_Fotor.jpg

IMG_2969_Fotor.jpg

IMG_3063_Fotor.jpg
 
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Make a plinth to hold two tone arms simultaneously !! I think they look cool as hell too.!!

IMG_0670-595x397.jpg

IMG_0472-595x397.jpg


Athanasios
 
Onebean said:
sqlsavior, can you help me understand which arm in the chart is optimum for the Denon 103, and which arm is optimum for a wide range of cartridges? I haven't listened to my Denon 103 yet, so I don't want to buy a white elephant tonearm that won't work good with other cartridges. I also have a Dynavector 20X, and an Ortofon MC20MKii that I would like to have the option of running on this arm. Thanks for the help.

Onebean
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Any of the 750s should work with your Denon and Dynavector cartridges, and maybe even the Ortofon, too, I would think, partly because they are damped. The Denon would prefer the heavier, and the Ortofon the lighter. Someone with more experience might weigh in on the Ortofon...
 
Onebean said:
I don't consider them better, I have no real knowledge or experience with the differences. Looking at the Jelco 9" and 12" arms, the price difference isn't that much. If the 12" is better, I'll lean towards it, if there are compliance issues, I'll stick with a 9".

The cartridge I plan to use is a Denon 103. I have read that the Jelco 750D is a good match for the Denon. I don't know if the same is true for the 12" version.

Onebean
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I’ve used a 12” Jelco with a Zu 103 and it’s a fantastic match.
:thumbsup:
 
totem said:
The first pic shows a 9" arm and the other split 12" -10.5 /10 armboards.
The split armboard can be changed for a 1 piece as there were half a dozen spare armboards made for a variety of
possibilities.

The arm cutouts are a labyrinth style where you have varying opening size's as you
go down versus a large hole.

View attachment 1034883

View attachment 1034884

View attachment 1034885
Click to expand...
Thanks for reposting that build. It is very much in line with what I have in mind for the Denon DP-80 I have coming. Bit of router work to do....
FullSizeRender.jpg
 
IMO, it's a compromise, with 12" being at the end of sensible Loof Lirpa probably went longer with his designs. If you do a DIY you can keep the mass very low with easily available materials that weren't so easily available back in the day.
 
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