advertisement


Manticore Mantra repairs

Yep, sorry guys, a quick Google around seems to show Rega and Systemdek recommend high viscosity gear oil... I sit corrected (as I'm not standing.) Must admit that the AR XA has quite high clearance between spindle and shaft. Don't know about Rega etc, but I wonder if clearance also comes into the equation as precession is what kills reproduction. I also wonder if in the case of the AR tables, low torque motors require lower viscosity lubrication so as not to overload or slow the motor.
 
fatcat said:
The ball won’t come out; it’s been pressed onto bearing hole. The ball burnishes the bearing hole, producing a very smooth finish.

Manticore instructions advise that hypoid 80 should be used. In fact they supply a small vial containing hypoid 80, for topping up the bearing.
Click to expand...
Are you referring the the standard Manticore bearing, or 'Megabearing' that was subsequently offered as upgrade?

Ah ha, never mind, I just found a copy of the Megabearing flyer in which Doug Hewitt described the standard bearing as also having a captive ball.

@Rob88,

Your ball bearing isn't meant to be removed. Best thing would be to half fill the well with meths, give it a good swish round and then soak all back up and let dry thoroughly before putting in the 3 x drops of 80W oil.
 
Last edited:
If anybody have a few drops of suitable oil for the mantra, I would be interested. As I said, I don’t see the point of buying a litre to use 3 drops.

I’m trying to adjust the suspension for about 3 hours now. I’m trying to achieve the best vertical bounce. It is actually very difficult. Also the platter seems to be level (I’m using a level for that) but still the bounce isn’t perfect and I can’t get any better.


Edit: I finally achieved a satisfactory setting for the suspensions. Probably not perfect but most likely the best I can do, at least for tonight
 
Craig B said:
Are you referring the the standard Manticore bearing, or 'Megabearing' that was subsequently offered as upgrade?

Ah ha, never mind, I just found a copy of the Megabearing flyer in which Doug Hewitt described the standard bearing as also having a captive ball.

@Rob88,

Your ball bearing isn't meant to be removed. Best thing would be to half fill the well with meths, give it a good swish round and then soak all back up and let dry thoroughly before putting in the 3 x drops of 80W oil.
Click to expand...

Yes, this is how I cleaned it. The oil was a bit black so it probably was time to change it. I’ll clean it again when I’ll get the right oil. Thank you
 
Rob88 said:
I’m trying to adjust the suspension for about 3 hours now. I’m trying to achieve the best vertical bounce. It is actually very difficult. Also the platter seems to be level (I’m using a level for that) but still the bounce isn’t perfect and I can’t get any better.
Click to expand...


I wouldn’t worry about platting the platter and plinth level, mine isn’t. It’s more important to get the bounce right.

A few years ago I decided to set it up with the plinth and platter perfectly level, sounded terrible. Went back to setting it up so the bounce was right, platter and plinth are not parallel with each other but it sounds fine.
 
fatcat said:
I wouldn’t worry about platting the platter and plinth level, mine isn’t. It’s more important to get the bounce right.

A few years ago I decided to set it up with the plinth and platter perfectly level, sounded terrible. Went back to setting it up so the bounce was right, platter and plinth are not parallel with each other but it sounds fine.
Click to expand...

It seemed to me that it is almost impossible to have both the plinth and platter leveled and the perfect bounce at the same time.

I tried for about 3-4 hours, and at the end I also decided to just get the bounce right like you suggest. I could probably do better but I’m fairly satisfied. I tried the bounce while playing a record and it seems to work very well so I will leave it as is.

I then adjusted the cartridge and the weight. I decided to go for 1.8 g and it sounds really good. I’m impressed by that turntable. I’m now waiting to receive the blue belt from Mike. @cj66 I hope you enjoy your Mantra as much as I do. What a nice TT

The only thing I’m unsure is that the tonearm drift slightly toward to exterior of the turntable when I lift it. Not sure if it’s normal. It may need adjustment.
 
"This is the way" as The Mandolorian would say ;).... almost.

I start with perfectly level support, perfectly level plinth and lastly perfectly level platter with the arm board centred to its cut out in the plinth.

Then tune the bounce, a few tiny tweaks later I can achieve all-level with perfect bounce. If you can't I suggest turning the springs. It DOES sound best this way, unless the springs are either too slack or too compressed.

My Mantra is sounding very good indeed and I still haven't put the AT-VM95ML RigB on :eek: Just a little dark on the HFs but that is due to the pf loading change in the Phono stage to suit the AT.

Yes it's an excellent deck, Axis etc. stomper! In my not so humble opinion :p
 
@Rob88,

I'll echo @cj66's suggestion of "turning the springs" above, as these exhibit a natural list to one side when under load.

Basically, with the plinth perfectly level and the sub-chassis fully loaded (including mat and record on), check from below that each top rubber grommet is centred wrt its hangar bolt. Any that are off centre need lifting up off from the adjustment nut at the bottom such that both top rubber grommet and spring can be rotated as one within the metal sub-chassis hole. This is repeated for each off centre spring/grommet until the top grommets are centred wrt each threaded hangar bolt. IOWs, rotating the springs shifts the chassis due to the aforementioned natural list of the springs whilst under load. When all are centred, the chassis is likely to move more stably up/down without teetering.

As it can be difficult to see through the springs when these are under load, one can simply gently shift the chassis laterally in N/S and E/W directions until it seems to have the same gap between grommet and bolt at each corner of the triangle that is made up of all three.

As visual reference, the following graphic is a crop from the original Sondek LP12 setup manual.

susp_t1.gif
 
Rob88 said:
The only thing I’m unsure is that the tonearm drift slightly toward to exterior of the turntable when I lift it. Not sure if it’s normal. It may need adjustment.
Click to expand...
Assuming you have the anti-skating bias* set for slightly less than or equal to the 1.8g downforce, then a slight outward drift during cueing can often be down to the cuing platform (with rubber strip?), as well as the underside of the portion of the tonearm tube that contacts this, needing cleaning to restore grip. A gentle wipe with a slightly damp cloth should restore this.

* Anti-skating bias applies an outward force intended to cancel the inward force that is a consequence of necessarily having an inward offset angled heashell/cartridge on a pivoting tonearm (in order to keep the cartridge/cantilever/stylus as close as possible to a tangent to the groove across the record, when this can only be true at two points due the the path being an arc).
 
Last edited:
I have followed all of your advices and tried to adjust it the best I can. I started with the plinth then the platter with mat and vinyl like I did before.

after 2h30 I’ve managed to get it leveled the best I can. I tried to center the bolts but 1) it was difficult to see 2) when they looked centered the plater wasn’t necessarily leveled. So I decided to go for the best level I could find instead although the bolts are not far off

not sure the bounce is better than yesterday to be fair, maybe even a tad worse, but it seems acceptable. I’m not sure.

When I mounted back the under plinth, I had to re level the feet. They’re not too nice, I may invest in something better as I had to level the TT with some tissue underneath. That’s all I had on hand for tonight

I then re adjusted the tonearm weight. The cartridge is a goldring 1012gx. This time I adjusted it on 1.7g instead.

I think what did the arm to drift sideways was the antiskating. It’s a rega rb250, so it’s fairly inaccurate. I lowered it close go 1/1.5. I have the feeling that it doesn’t sound as good with 1.7g than 1.8g but I doubt it can make a difference. Either I’m overthinking or maybe the suspension are a bit too stiff this time, or the anti skate isn’t correct. I don’t know

Anyway, I think I’ll enjoy the turntable as is, at least I’ll leave the suspension alone for now. I doubt I can do much better. Thank you all for your advices and shared knowledge
 
Strangely a friend of a friend contacted me last night about his Mantra ( RB250 ) tuning problems.
On seeing a piccy I saw an understandable but huge mistake. He'd adjusted the suspension until the armboard was level with the plinth, like many decks demand.
Not on the Mantra, the armboard is meant to have its top surface just below the underside of the plinth cut out but centred. That is why the Rega arms need a spacing collar.
If the belt doesn't drop off the deck will be ultra twitchy like this and sound really bad.

Thought I'd throw that in, just in case.
 
FWIW. Going back to the thrust bearing on the motor. If it's anything like the ones I use then what I did was to use a stethoscope to listen to the motor vibration in the top plate and adjusted the thrust bearing screw to minimise what I could hear.
 
A few photos of the motor fitted to the top spec Mantra.

It came with a vial of grease which I use to lubricate the bottom of the motor.

1wD9Ic.jpg

UrXnSB.jpg


oE8WSt.jpg
 
I finally found the time and inclination to swap out the Goldring Elan for the new AT-VM95ML RigB.

20221008-195419.jpg


Flippin' 'eck!
Not so much a breath of fresh air as a thundering revelation.
The Elan is shown up for being the not so good, even for budget, cartridge it is.
Totally out classed in every department.

For now I've settled for a snadge over the nominal 2.0gr tracking weight. After an hour of action the bass is starting to dominate slightly so I may pull back slightly on that once fully bedded in.

20221008-194721.jpg


I should really treat myself to a better alignment protractor.
 
The old Hi-Fi Review freebie will be to Baerwald (aka Löfgren 'A') which is likely why your cartridge appears skewed in the headshell.

Better to go with Rega's own freebie and align by the cartridge body and headshell, not the cantilever.

rega-alignment-protractor.jpg
 
Maybe the angle of the picture. The cartridge is very marginally off centre in the headshell.

Plus, it was my understanding that Rega RB250s etc. were indeed Baerwald/Löfgren A.


"Rega Lofgren A (Baerwald) Protractor
A Lofgren A protractor for Rega arms mounted at 222MM, aligning to the IEC standard null points of 66 and 120.9MM. Most Rega arms follow the 222MM mounting standard, including the RB300, 301, 303, 330, 808, 2000 and many others."

Screenshot-20221009-025025-Xodo-Docs.jpg
 
Rega's are designed to Stevenson, at least an approximation of same. They've only recently published specific overhang and offset values for their tonearms, which confirms this.

An interesting aside to all of this is that, unlike his predecessors, Stevenson had an advantage in that he could take into consideration that distortion from tracking error increases if elliptical styli are used (Note: 'distortion from tracking error' not 'distortion from tracing error'). His 'Pickup Arm Design - 1' and 'Pickup Arm Design - 2' are worth a read, even if the maths can be a bit daunting...

 
Okey dokey.

I've found downloads for both and I'll give them the acid test.
Thankfully, to the eye they look identical so the differences will be suitably tiny...
 
You must log in or register to reply here.


advertisement


Back
Top