TT experts' help needed! Unstable platter problem.

Discussion in 'Playback Devices' started by Cagri, Mar 15, 2004.

  1. Cagri

    Cagri Second Unit

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    I posted the following message to an existing thread of mine but did not get any attention, so here goes:

    Well, I went ahead and bought a Project debut 2.. It's project's entry turntable, but like a state of the art masterpiece to me after the turntable I used to own many years ago...

    It's a belt drive unit, I placed the belt as proper as possible, but the platter doesn't turn perfectly flat. It's like it's not been centered and makes ups and downs, is this normal?

    Also, there's this anti-skating force adjustment which I am not sure I've done correctly. The manual isn't very helpful, it tells something about downforce and gives numbers like 10-15mN, 15-20mN, 20mN and bigger.There's also a plastic thingy which looks like a tool to measure this downforce with a hole on one side and these 10-15-20 mN numbers on it but I have no idea what to do with it...

    When I use the tt without the mat on the platter, it seems to be turning on level but still not perfectly so.

    I had the unit running as it is by the way and the sound is ver pleasing. It's airy, it's more natural and warm than CDs..

    Any help out there please?
     
  2. Allan Jayne

    Allan Jayne Cinematographer

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    No it is not normal except for el-cheapo models. The bare platter should turn perfectly flat and true. You may want to return the turntable.

    Did the mat come with the unit? The mat may be of an inferior quality.

    The ideal way to set skating is to get a record with no grooves (an unused recording blank). "Play" this record and adjust the antiskating control so the arm does not drift either in or out. Measurements in grams are just estimates.

    The ideal downforce (tracking force) depends on the groove excursions and there are no easy to use inexpensive measuring tools. My own recommendation is to use the maximum suggested by the cartridge manufacturer if you have records with a large dynamic range and high frequency content (more correctly having any sudden or wide groove undulations), otherwise use 2/3 the maximum if you have just average records. If the tracking force is too low the needle may bounce and that is said to cause more record damage than just having the tracking force a bit too high.

    I have never heard of tracking force in nM (newton-meters?). All the tracking force measurements I have done are in grams or rarely small fractions of ounces.

    Video hints:
    http://members.aol.com/ajaynejr/video.htm
     
  3. Cagri

    Cagri Second Unit

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    Allan, thx for the reply.
    Yes the mat came with the unit. It looks fine, but when it is on the platter and I play a record the tone arm makes ups and downs for about 1/4 of an inch. Without the mat it moves about 1/8 of an inch. The records are good, I tried with a new record as well and same thing happens.

    I may have told the situation incorrectly though, I am not sure if the platter turns perfectly flat or not because I didn't check that. I only checked when playing a record, either with or w/o the mat. Whether it makes a difference I do not know. I mean, if the record is flat and it doesn't turn flat then that means the platter is not turning flat I guess...
     
  4. John Watson

    John Watson Screenwriter

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    Interesting information...

    I'm planning on getting a Project this month, if the dealer has the bright blue model that is on display in stock. It looks so cool [​IMG]

    I will show him these messages tho, and see if he says anything.

    I remember lots of visible rising and falling on old records, and always assumed that it was caused by warping in the records, which wasn't always so visible. As long as it didn't throw the stylus up I didn't worry about it.

    BTW, I remember taping pennies or nickels to tone arms to keep the needle on track, but that was a looong time ago [​IMG]
     
  5. GuyMaren

    GuyMaren Agent

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    If you have access to a dial indicator, you might be able to use that to get the precise measure of deviation from flatness (the runout). Then you can contact the manufacturer and ask them whether your TT is within their spec. for runout.
     
  6. Cagri

    Cagri Second Unit

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    For now I am using the unit without the mat.
    I called the dealer, he checked one unit in the store and told me that it wasn't rotating flat, but the movement was not as much as mine. I'll try and go to the store this weekend.

    Any Pro-ject debut (or another model) owners to share their experience please?
     
  7. DavidLW

    DavidLW Stunt Coordinator

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    Cagri-

    Put a record on and look at the label area and note where the record rises.

    Stop the turntable and wait for it to come to a complete stop.

    Pick off the record and rotate it 180 degrees.

    Turn the turntable back on and look at the label again area and note where the record rises.

    If it's rising in the same area as before, then it's the record that is warped.

    If it's rising in a different area of the label then it's the platter.

    If it's the record, you can try to buy a record clamp to hold down the record in the center.
     
  8. Cagri

    Cagri Second Unit

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    David, thx for the tip..

    For the record, I had tried about 15 records 2 of which were new, and with all of them the tonearm was moving up and down so I was sure that it was the platter. I did what you said, and then I sat down and tried about all of my records... It's not the platter, it's the records and I discovered that only 3 of my records which I'd bought 15-17 years ago are fine... [​IMG]
     

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