Mission Mechanic tonearm - bearings

[don_perron]

Hi.
I own a Mission Mechanic tonearm. Very nice device - but: the bearings
are not in best condition. The german distribution of Mission products
can't help. Since I highly appreciate the very good performance I'd
rather have repaired this tonearm than buy another one. Does anybody
know by accident where I can get this problem fixed?

[Allen Sorenstein]

On 5/1/04 20:02, in article ,
"don_perron" > wrote:

> The german distribution of Mission products
> can't help. Since I highly appreciate the very good performance I'd
> rather have repaired this tonearm than buy another one. Does anybody
> know by accident

What kind of "accident" finds you bearings? They're likely custom machined,
and if the distributor won't help you you're SOL.

So much for "quality" service from these so-called "high end" companies!

[Marc Phillips]

Allen Sorenstein said:

>On 5/1/04 20:02, in article ,
>"don_perron" > wrote:
>
>> The german distribution of Mission products
>> can't help. Since I highly appreciate the very good performance I'd
>> rather have repaired this tonearm than buy another one. Does anybody
>> know by accident
>
>What kind of "accident" finds you bearings? They're likely custom machined,
>and if the distributor won't help you you're SOL.
>
>So much for "quality" service from these so-called "high end" companies!

Uh, Mission is mid-fi at best. And they're part of a rather large corporation.

Boon

[don_perron]

Hi all,

thanks for having a share in my problem. The problem ist the
following: the bearings seem to be a little bit worn out - they aren't
really tight, that means one or all bearings (horizontal and/or
vertical) have too much clearance. The bearing for horizontal tracking
might be a ball bearing. The bearing for vertical movement is a needle
bearing with ceramic bearing shells (as far as I know...).
Of course I could try to fix the problem on my own. Maybe it's just a
matter of adjusting. But my first idea was to find somebody who is
able to assemble spare parts (especially the ceramic bearing shells)
if necessary...
Nevertheless I would appreciate all hints that could help to get rid
of this problem...

Marc, in general I agree with your statement - Mission is mid-fi. But
there is at least one exception - and that's the Mission Mechanic
tonearm. Construction and appearance is similar to the Linn Ittok or
Ekos. The Mission tonearm sounds really great. At least when the
bearings are all right...

Regards

Andreas

[Arny Krueger]

don_perron wrote:
> Hi all,
>
> thanks for having a share in my problem. The problem is the
> following: the bearings seem to be a little bit worn out - they aren't
> really tight, that means one or all bearings (horizontal and/or
> vertical) have too much clearance. The bearing for horizontal tracking
> might be a ball bearing. The bearing for vertical movement is a needle
> bearing with ceramic bearing shells (as far as I know...).

Generally, needle bearings are adjustable. The needles are threaded and
slotted for a screwdriver. Beware of over-tightening.

The bearings in a tonearm are relatively heavily preloaded by the weight of
the arm. This is not the front suspension of a car where the bearings can
have a negative load. Therefore, it generally doesn't matter if they are a
little loose, unless they get so loose that there are alignment or friction
problems.

[Sander deWaal]

"Arny Krueger" > said:

>Generally, needle bearings are adjustable. The needles are threaded and
>slotted for a screwdriver. Beware of over-tightening.

>The bearings in a tonearm are relatively heavily preloaded by the weight of
>the arm. This is not the front suspension of a car where the bearings can
>have a negative load. Therefore, it generally doesn't matter if they are a
>little loose, unless they get so loose that there are alignment or friction
>problems.

Loose bearings will alter the resonance frequency of the tone arm, as
well as increase the amplitude of resonances because of ineffective
transfer of energy at the needle's points.

Generally, they can make a cart-arm combo sound like ****.

--
Sander deWaal
Vacuum Audio Consultancy

[Arny Krueger]

Sander deWaal wrote:
> "Arny Krueger" > said:
>
>> Generally, needle bearings are adjustable. The needles are threaded
>> and slotted for a screwdriver. Beware of over-tightening.

>> The bearings in a tonearm are relatively heavily preloaded by the
>> weight of the arm. This is not the front suspension of a car where
>> the bearings can have a negative load. Therefore, it generally
>> doesn't matter if they are a little loose, unless they get so loose
>> that there are alignment or friction problems.

> Loose bearings will alter the resonance frequency of the tone arm,

No way. A tone arm is a classic mass-spring damper system. If the bearings
have too much friction they can contribute to the damper part of the
equation, but they aren't supposed to have appreciable friction.

> as well as increase the amplitude of resonances because of ineffective
> transfer of energy at the needle's points.

No way. The energy gets transferred the same because the normal forces
eliminate the possibility of zero or negative forces at the pivot points.
Basically, tracking force and groove tracking make only microscopic
contributions to the forces on the bearings.

> Generally, they can make a cart-arm combo sound like ****.

High friction can make a cart/arm combination sound like crap, but I
already discussed the consequences and limits of that.

[Mark]

(don_perron) wrote in message >...
> Hi all,
>
> thanks for having a share in my problem. The problem ist the
> following: the bearings seem to be a little bit worn out - they aren't
> really tight, that means one or all bearings (horizontal and/or
> vertical) have too much clearance. The bearing for horizontal tracking
> might be a ball bearing. The bearing for vertical movement is a needle
> bearing with ceramic bearing shells (as far as I know...).
> Of course I could try to fix the problem on my own. Maybe it's just a
> matter of adjusting. But my first idea was to find somebody who is
> able to assemble spare parts (especially the ceramic bearing shells)
> if necessary...
> Nevertheless I would appreciate all hints that could help to get rid
> of this problem...
>
> Marc, in general I agree with your statement - Mission is mid-fi. But
> there is at least one exception - and that's the Mission Mechanic
> tonearm. Construction and appearance is similar to the Linn Ittok or
> Ekos. The Mission tonearm sounds really great. At least when the
> bearings are all right...
>
> Regards
>
> Andreas

The Mechanic tonearm doesn't seem to be very well known in North
America. It was made by GB Tools who also manufactured the Zeta arm.
Don't know if GB Tools is still around or not, but Moth in the UK was
a distributor of Zeta arms and they might be of some assistance. Mike
Harris is the guy to contact. Try the following address, and good
luck. As a current owner of a Mechanic arm, I can vouch for just how
good they can sound.

www.hi-fi-accessories-club.mcmail.com/

Mark

[Sander deWaal]

"Arny Krueger" > said:

>> Loose bearings will alter the resonance frequency of the tone arm,

>No way. A tone arm is a classic mass-spring damper system. If the bearings
>have too much friction they can contribute to the damper part of the
>equation, but they aren't supposed to have appreciable friction.

If you'd care to do some measurements yourself, you'd see what I mean.

>> as well as increase the amplitude of resonances because of ineffective
>> transfer of energy at the needle's points.

>No way. The energy gets transferred the same because the normal forces
>eliminate the possibility of zero or negative forces at the pivot points.
>Basically, tracking force and groove tracking make only microscopic
>contributions to the forces on the bearings.

When listeners all over the world report that using a different mat
alters the sound because of resonance control, what order of magnitude
of voltages are we speaking about?
Good vinyl playback IS about resonance control.
In the uV range, things like loose bearings count.
Viz the OP's question, and experience with vinyl playback by thousands
of enthusiasts, like myself.

--
Sander deWaal
Vacuum Audio Consultancy