View Full Version : Not happy with Jelco 750L / SPU combination
I bought the Jelco SA-750LB about 14 months ago, I used it mostly with my Denon 103R. This combination sounds very good. Last autumn I did buy a (new) Ortofon SPU Synergy, but the cart was tracking bad and distortion could be heard so I returned the SPU. Received a new one about 6 weeks ago. The new one tracks better but more important no distortion anymore.
But overall I am still not very hapy with the combination. I spend all afternoon in testing and comparing the 103R vs SPU Synergy.
The tracking of the Synergy is still bad compared to the 103R. The Synergy tracks max 60 um at 315 Hz, at 70 um it jumps out of the groove. The 103R track 80 um at 315 HZ without any distortion.
Real problems arise when adjusting the antiskating with the Synergy mounted, using a grooveless record, VTF @ 3g, Antiskating @ max (a bit more as 3) the Synergy moves rather quick from the out to inside and if I did not lift the arm in time it would have hit the record label. The same test with 103R gave much better result, VTF @ 2.5g, Antiskating @ 2.5 the 103R moves slowly from out to inside and at a few centimeters from the label the cart stops moving and stays stable at this distance.
I tried the Synergy with higher and lower VTF, higher and lower antiskating settings but the best was at the recommended setting of 3g.
The sound of the Synergy is not that much different compared to the 103R, it reveals a bit more detail while the 103R does have a better bass performance. This afternoon I also removed the damping oil from the tonearm and did all the tests again without noticeable differences but the sound became more relaxed both wth the 103R as with the SPU Synergy. I can't figure out why the sound became more relaxed without the damping oil.
My conclusion, the SA-750LB / SPU Synergy combination is not the worlds best but the SA-750LB / Denon 103R is a real good one.
It seems that for a SPU the SA-750LB lacks enough antiskating force.
Ronald
I have a 750 L and have found the anti skate needs to be on 3 for a koetsu black and a ortofon mc 30.
I'am guessing the spu is to heavy for the Jelco.
Audioman
09-03-2013, 21:21
Is the cartridge alignment correct? For SPU you can't alter at head shell so arm base may need re-positioning. In that case you will need a new arm board cut. I would suggest alternatively a vintage SME or the new M12R as alignment is achieved by adjusting the base.
Is the cartridge alignment correct? For SPU you can't alter at head shell so arm base may need re-positioning. In that case you will need a new arm board cut. I would suggest alternatively a vintage SME or the new M12R as alignment is achieved by adjusting the base.
I did forget to mention but the arm is aligned correctly. I am also pretty shure the VTA setting with both 103R and SPU is 100% level.
Ronald.
Are you using the standard Jelco collar? It can cause problems with azimuth.
When tightening the locking grub screw the force can twist the arm in the collar causing a change in azimuth. Worth checking. See here (http://theartofsound.net/forum/showthread.php?t=7359) for a possible solution.
I've been using an SPU GME and a 750L for 18 months+ (with a shuggie collar) and they're superb together, tracking is A1.
Edit:
Sorry, you've said the denon tracks fine, so very unlikely to azimuth problem. Ignore me.
Ah makes sense.
Need to get one of these if still available.
Are you using the standard Jelco collar? It can cause problems with azimuth.
When tightening the locking grub screw the force can twist the arm in the collar causing a change in azimuth. Worth checking. See here (http://theartofsound.net/forum/showthread.php?t=7359) for a possible solution.
I've been using an SPU GME and a 750L for 18 months+ (with a shuggie collar) and they're superb together, tracking is A1.
Edit:
Sorry, you've said the denon tracks fine, so very unlikely to azimuth problem. Ignore me.
I received Shuggies colar before the Jelco. :lol:
Did you do some tracking and/or antiskating tests with your GM E? As far as I know the GM E needs a VTF of 4g and should be able to track 65um @ 315 Hz. As soon as I raise the VTF above 3g the tracking gets worse (distortion can be heard at 50 and 60 um) and also the antiskating gets worse (the speed the arm moves to the inside increases).
Ronald.
I received Shuggies colar before the Jelco. :lol:
Did you do some tracking and/or antiskating tests with your GM E? As far as I know the GM E needs a VTF of 4g and should be able to track 65um @ 315 Hz. As soon as I raise the VTF above 3g the tracking gets worse (distortion can be heard at 50 and 60 um) and also the antiskating gets worse (the speed the arm moves to the inside increases).
Ronald.
I track my GME at 4g, AS is set at 3g. That said, moving the AS doesn't seem to make much difference at all. I've not used a test record, I've never felt the need to. It tracks everything very well including very powerful orchestral music. I've never heard any distortion during use. I did check the alignment a while back with Dr Feickert tool and was more or less spot on.
I'm sorry you're having problems and that I can't help. I hope you manage to get it sorted.
I track my GME at 4g, AS is set at 3g. That said, moving the AS doesn't seem to make much difference at all. I've not used a test record, I've never felt the need to. It tracks everything very well including very powerful orchestral music. I've never heard any distortion during use. I did check the alignment a while back with Dr Feickert tool and was more or less spot on.
I'm sorry you're having problems and that I can't help. I hope you manage to get it sorted.
It is more or less a technical problem only, sound wise it sounds good. But I do get more cracks in my records since I use the SPU that's why I checked everything again last afternoon.
But now i have your attention, how do you cope with the load of the SPU? My Synergy needs a load resistance between 20 - 50 ohm. My tube phono pre (MM) does have an input impedance of 47k and I use a SUT of 1:20, I have soldered a 22k resistor in parallel with the 47k input resistor, now i have a load of 37.5 ohm. If I omit the 22k the high frequencies ar making me nervous.
Ronald.
Real problems arise when adjusting the antiskating with the Synergy mounted, using a grooveless record,
I tried the Synergy with higher and lower VTF, higher and lower antiskating settings but the best was at the recommended setting of 3g.
My conclusion, the SA-750LB / SPU Synergy combination is not the worlds best but the SA-750LB / Denon 103R is a real good one.
It seems that for a SPU the SA-750LB lacks enough antiskating force.
Ronald
I am not familiar with the Jelco/SPU combination, but I have 40 + years of record player setup and design experience.
I can assure you that a grooveless record is a very approximate (at best) way of setting bias. The reason is simply that the drag force you are trying to compensate for with bias is the drag between the stylus active surfaces and the groove. On a grooveless record you are observing the drag of the stylus -tip- against a shiny bit of vinyl. The likeleyhood of this being the same as active surface against groove wall is slim to none. There is no standard for the shape of the tip of the stylus, which is not in contact with anything whilst playing a record (or it shouldn't be!) so some are quite a tight radius, some aren't. The Denon is a conical stylus IIRC and the Synergy an elliptical. It is likely, therefore, that the 103 has a "blunter" lower point than the Synergy which would lead to it pulling into the centre of a grooveless disc more slowly than the SPU.
This tells absolutely nothing about bias setting, I'm afraid...
The SPU has never been a high level tracking specialist anyway, it has other strengths.
Whilst cartridge design went down the tracking demon route the baby got thrown out with the bathwater in many enthusiast's opinion.
It is more or less a technical problem only, sound wise it sounds good. But I do get more cracks in my records since I use the SPU that's why I checked everything again last afternoon.
But now i have your attention, how do you cope with the load of the SPU? My Synergy needs a load resistance between 20 - 50 ohm. My tube phono pre (MM) does have an input impedance of 47k and I use a SUT of 1:20, I have soldered a 22k resistor in parallel with the 47k input resistor, now i have a load of 37.5 ohm. If I omit the 22k the high frequencies ar making me nervous.
Ronald.
More cracks on the record could simply be the elliptical stylus on the synergy reads the groove (including the damage) better than the conical...
OTOH a 20:1 SUT is a mismatch to a SPU so it will not be performing to specification. I am not sure what the effect of the load resistor may be, but I would bet the differences you hear between 103 and SPU are due to one matching the SUT and the other not, there will be a big difference in HF, as it seems you have found.
My advice is to do it all by ear. I would say any differences you dislike between SPU and 103 are 50x more likely to be due to loading mismatch with the SUT than the arm.
More cracks on the record could simply be the elliptical stylus on the synergy reads the groove (including the damage) better than the conical...
OTOH a 20:1 SUT is a mismatch to a SPU so it will not be performing to specification. I am not sure what the effect of the load resistor may be, but I would bet the differences you hear between 103 and SPU are due to one matching the SUT and the other not, there will be a big difference in HF, as it seems you have found.
My advice is to do it all by ear. I would say any differences you dislike between SPU and 103 are 50x more likely to be due to loading mismatch with the SUT than the arm.
Frank, thank you for your explanation why I should not use a grooveless record for AS adjustments.
I mentioned the cracks (and also some real nasty plops and ticks and on one record even a jump to the next groove) because I am sure they are new and I fear that the first 'faulty' SPU Synergy I had is the cause of them.
About the SUT, I think a 1:30 SUT is advised for SPUs in general but the Synergy has a rather high output of 0.5 mV compared to the others. A 1:10 would do but than the load resistance will be 470 ohm wich is to high, that is why I strapped my SUT to 1:20 (can't go higher) but than the load resistance is still to high (117 ohm). To get the right load resistance I soldered the 22k in parallel with the 47k and I like the sound this way (the right load resistance removes a edgy sound) . As long as the load resistance on the secondairy side of my SUT is above 10k the SUT is doing fine (according to the Lundahl technical data).
The sound of the Synergy is fine and I prefer it a bit above the sound of the 103R but I still have my doubts about the tracking capabilities of SPUs.
Ronald.
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