There's no way that the Jelco SA-750e has an effective mass of 21 grams. My Zeta arm is 16 grams and is MASSIVE compared to the Jelco. Maybe they gave you the weight in some weird Japanese measurement? |
Dear Alun: No, 21grs is on the high part of a medium mass, there are high effective mass tonearms in excess of 40grs.
Don't worry about before you mount and test the Celebration on it, after that you can decide if that tonearm is a good match to the cartridge and remember that the Jelco is a removable headshell design so you always can use not only a different headshell weight but a different headshell build material that can help to the Celebration shows at its best.
If you can change the headshell stock wires for the Ikeda S-50 that you can find through an ebay seller: 2juki, this sole change makes a difference for the better.
Regards and enjoy the music,
Raul. |
Well I did some looking around and it appears that the headshell is already 12grams and is about the lowest I could find.
I'm gonna post another thread on my tonearm seach.
Thanks fellows! |
Mofimadness, you read it right 21Grams, and you should see some of the weights for the Ortofon arms!
Now that said I did do some calculating and it will work with my Sumiko, but I'm having a change of heart and leaning towards the VPI 10.5i or a used Audiocraft AC3000. They both have similar features except VTA on the Fly by VPI. Also the Classic is a nice choice.
Decisions decisions. |
Another choice you may not have thought of, is Origin Live. They have arms priced over a fairly wide range. |
I also emailed Jelco yesterday. I am about to buy the Jelco 750E. Their email to me said that the effective mass of the jelco is 13.26 grams.
13.26 Sounds right, 21g seemed a bit high considering the build of the arm.
Here is a cut paste of the email.
Thank you for your inquiry for SA-750E effective mass.
SA-750E effective mass is 13.26gr ( with headshell without cartridge)
Best regards,
Haruo Uchida/sales manager
[JELCO] Ichikawa Jewel Co.,Ltd.
jelco@celery.ocn.ne.jp
市川宝石株式会社
mail@jelco-ichikawa.co.jp |
21 grams is medium mass. It will work better than all those skinny-mini 10 gram arms, especially for low-compliance cartridges.
In general higher mass arms control the cartridge instead of the other way around - am I right, Raul ?? |
The Jelco headshell is a perfect candidate for the drill. A lot of mass can be removed without impacting the rigidity by drilling holes. I can't remember the drill pattern or how much mass was removed, but IIRC, there were a couple of people on vinylengine that pretty successful. |
To my way of thinking, 21 grams is in the range of "high mass", not "medium mass". Medium mass is more like 10 to 15 grams, IMO. Of course, to some degree it is a matter of opinion. In any case, 21 grams is not stratospherically high. Most notably, the well-liked (by some) Fidelity Research FR64 and 66 are much higher in mass. And some have mated the FR tonearms with relatively high compliance cartridges and report good results. You can easily find headshells that weigh as little as 6-8 grams, so as to effect a reduction in effective mass for the Jelco. But like Raul says, it is best to keep an open mind; don't be a slave to those formulae for mating compliance to effective mass. |
IMO, the classification of low, medium and high mass arms seems a bit arbitrary. The goal should be to match a given cartridge compliance with the effective arm mass. Plenty of calculators around to help in matching. |
"In general higher mass arms control the cartridge instead of the other way around - am I right, Raul ?? "
Interesting way to look at it. While the arm should provide a stable platform for the cart to track, there's a delicate balance between stability and hindrance. These days 21g is considered high mass. Most modern carts are between 15 and 22cu. The Celebration is 12cu and should be a near perfect match, compliance-wise.
Despite the Jelco sales mgr, the Jelco 750d is around 20g, so 21g for the 750e sounds about right. I suggest using as little fluid damping as possible, to preserve transient response. While good results can often be realized with compliance/mass mismatches, you'll experiment at your own risk.
Regards, |
Fleib, it's all relative. My highest compliance cartridge is a Denon DL-S1 at 14 cu - the FR-64fx I've got works well with this cartridge mounted in an Orsonic headshell and the small counterweight. Great cartridge for choral and chamber music, etc. When I want more body, I switch out to an Ortofon Synergy SPU and the W250 counterweight, which takes the effective mass up to 30-35 g, (more like an FR-64s). This combination also works well - sounds like a Koetsu with iron cajones !!
For flexibility in compliance matching, it really helps to have a removable headshell arm with light and heavy counterweights - the FR-64fx is still one of the best ! |
Dcbingaman, the DL-S1, 304, happen to sound best (to me) in arms of greater mass than their compliance/mass match would imply. Such is not the case with most high cu carts, IMO. Many of them will sound sluggish when the excessive eff mass with high moment of inertia, encumbers their performance. Resonant frequencies also go dangerously low.
Yes, it's all relative to the specific cart. Rules of cu/mass matching are a consideration, but not necessarily paramount. Having a removable headshell also adds to the eff mass, adds two more sets of connections, and creates additional arm resonance. Low mass arms tend to be less rigid and resonate with greater amplitude than damped high mass arms like the 750. YMMV. Pick your preference. In this case, OP is using a low cu cart and cu/mass considerations should not be a problem.
Regards, |
IMO, you don't want the tonearm to "control" the cartridge. You want the tonearm to allow the cartridge to ride as smoothly as possible through the curvaceous and treacherous grooves of an LP, without bouncing out. At the same time, the tonearm should not impede the cartridge. It's a tricky deal. |
If the cartridge compliance is low enough to cause the arm to move rather than the cantilever to move when the groove undulates back and forth, you get no coil velocity in the magnetic field and hence no signal. This happens ALL THE TIME with low compliance cartridges and too light tonearms on low frequency undulations. Hence light tonearms can sound lightweight.
Same goes for unipivots with too low a moment of inertia in the azimuthal axis. Because the groove is offset (below) the CG of the arm / cartridge, the groove will rotate the ARM back and forth about the unipivot point, rather than move the cantilever. That is what I meant by having the arm control the cartridge instead of the other way around. Gimbaled arms and linear trackers don't have it's extra monkey motion and have fewer problems reproducing low bass as a result. |
Matching arm to cartridge is all about allowing the cartridges motor to get excited in an optimal fashion, such that the cartridges virtues are realized mechanically and electrically.
An analogy would be to match a bikes frame weight to tire pressure. If you have a bike frame that weighs 200lbs! what will happen to your ride? It will get hard and bumpy if the weight overcomes the counteraction of the tire pressure.
So the right frame would be not too light and not too heavy RELATIVE to the actual tire pressure quotient (whatever it is) so that you get a NICE ride.
Not all tires are designed to work with the same tire pressures, so too with cantilevers "springiness". Some are stiffer and need just the right amount of weight to have a good ride. Remember over inflating the tires on your bike? It was a hard stiff ride. Too flat and the bike was sluggish and hard to pedal.
So, it's not about one controlling the other but about choosing an arm which will allow the cart to work within it's intended parameters so that it can sound it's best. Its about an ideal physical relationship to achieve a desired goal.
Once you've done that...don't forget to match the output of your cart with the input of your phono ! so it too is just right.
* |
