The tonearm in Technics 1200 decks is known, in some circles, of having good and rugged bearings... If they don´t have play and move freely, they must be in good form.
The manufacturer states a sensibility of 7 mg or so -I don´t know exactly the method that they use to measure that-... I don´t know, neither, if 7 mg is only a threshold, or if you get a full deflection of the tonearm with such a tiny weight... I believe that is more of a threshold thing, but I may be wrong.
By the way, 7mg is more or less the weight of 1 cm2 of A4 paper (75 g/m2) ; so you got a known reference to check out the sensibility of your arm.
In my case, to check vertical movement, I just make the tonearm balance -0 grams-, trying to avoid any influence of the cables (...and they influence a lot!)
When the tonearm stands still, you must add some piece of paper on the headshell to check out the easiness of movement - some ¨admitance¨, not a full deflection-. I think that some 20/25 mg is a safe limit, the less the better.
Another person that I know use to blow gently on the headshell, to check out ease of displacement.
With the blow expedient you can check out horizontal movement too: the arm should move freely, without sudden detents or ¨steps¨.
If I remember well, Linn used to check tonearms with a ¨pendulum¨ method (the tonearm, without headshell and without counterweight, and pending by it´s vertical bearing, must oscillate like a pendulum at least 15/20 times, or so )
Another evidence of good horizontal sensitivity is the response of the tonearm to the skate forces. You must use a flat lp (hard to find, unless you have some test records or, at least, Smashing Pumpkins ¨Adorè¨on vinyl, known to have some unrecorded side)...
With a cart tracking at +/- 2 grams, and with the antiskate in ¨0¨ you should see a clear movement towards the center of the record. If the stylus stucks in the same spot, something is out of shape.
And a last advice: if you get some evidence of acceptable sensibility, don´t try to re-adjust anything. It can be done, but is tricky. One night, a couple of years ago, I ended face to the floor, with an eyeglass and a flashlight, searching -and capturing them with a magnet- a myriad of miniature balls expelled from the bearings. When I finally found them, I had to remake the bearings using light grease to hold the bloody spheres in place...
Not funny.
The manufacturer states a sensibility of 7 mg or so -I don´t know exactly the method that they use to measure that-... I don´t know, neither, if 7 mg is only a threshold, or if you get a full deflection of the tonearm with such a tiny weight... I believe that is more of a threshold thing, but I may be wrong.
By the way, 7mg is more or less the weight of 1 cm2 of A4 paper (75 g/m2) ; so you got a known reference to check out the sensibility of your arm.
In my case, to check vertical movement, I just make the tonearm balance -0 grams-, trying to avoid any influence of the cables (...and they influence a lot!)
When the tonearm stands still, you must add some piece of paper on the headshell to check out the easiness of movement - some ¨admitance¨, not a full deflection-. I think that some 20/25 mg is a safe limit, the less the better.
Another person that I know use to blow gently on the headshell, to check out ease of displacement.
With the blow expedient you can check out horizontal movement too: the arm should move freely, without sudden detents or ¨steps¨.
If I remember well, Linn used to check tonearms with a ¨pendulum¨ method (the tonearm, without headshell and without counterweight, and pending by it´s vertical bearing, must oscillate like a pendulum at least 15/20 times, or so )
Another evidence of good horizontal sensitivity is the response of the tonearm to the skate forces. You must use a flat lp (hard to find, unless you have some test records or, at least, Smashing Pumpkins ¨Adorè¨on vinyl, known to have some unrecorded side)...
With a cart tracking at +/- 2 grams, and with the antiskate in ¨0¨ you should see a clear movement towards the center of the record. If the stylus stucks in the same spot, something is out of shape.
And a last advice: if you get some evidence of acceptable sensibility, don´t try to re-adjust anything. It can be done, but is tricky. One night, a couple of years ago, I ended face to the floor, with an eyeglass and a flashlight, searching -and capturing them with a magnet- a myriad of miniature balls expelled from the bearings. When I finally found them, I had to remake the bearings using light grease to hold the bloody spheres in place...
Not funny.
Hi,
I have experience adjusting the bearing on my SL-1200MK2 and it's not so easy.
You to have adjust just at the threshold of "no play" but you have to leave very little "play" because the locking nut will make them tighter and thats the hard part.
And you have to know which axis the slack is coming from.
I think I done quite qood on them and will leave them alone for a very long time.
Since I adjust them I have less subsonic garbage to the point that at low/mid volume I don't use a subsonic filter except on warp records.
Some thing that very little play can be more musical on some tonearm , Origin Live adjust there that way
Thanks
I have experience adjusting the bearing on my SL-1200MK2 and it's not so easy.
You to have adjust just at the threshold of "no play" but you have to leave very little "play" because the locking nut will make them tighter and thats the hard part.
And you have to know which axis the slack is coming from.
I think I done quite qood on them and will leave them alone for a very long time.
Since I adjust them I have less subsonic garbage to the point that at low/mid volume I don't use a subsonic filter except on warp records.
Some thing that very little play can be more musical on some tonearm , Origin Live adjust there that way
Thanks
I couldn't do the test you described since I don't have a blank LP. However, if I remove the mat and set the tracking force to 0 to let the arm hover level. It will stay if anti-skate is set to 0 but as soon as it is turned up just a little the arm moves to the outside.
Yeah, I figured it's best left alone unless it definitely needs it. As it is, making adjustments could more easily make things worse than better.
That would be cool if they made a cartridge/stylus specifically for plowing through the crud. Some of my LP's have crud deep in the grooves that won't seem to come up by cleaning. Though I don't have one of those hardcore vacuum-cleaning machines.
Do any of you guys have good mat recommendations? I'm looking for a conductive one that also provides good acoustical isolation. Without spending a fortune
Headroom. One of my carts is a Decca, and I've seen that put out 2V on click transients on a storage scope. The last pre I built for it ran on very high HT and had a lot of swing on the front end and only in the most extreme damaged / dirty discs would it clip. The noise, whilst still present was as you said 'on a different level' and didn't make itself known.Hanginon said:
Even if the phono pre didn't clip I'd think it would either make your amp clip or blow your speakers.
Brett said:
I've heard it said that one of the reasons Deccas are so hated by some people is that they were listened to in systems where their unique 'speed' often overloaded the RIAA networks, with unsurprisingly nasty results.Graham Slee, for one, pays partilcular attention to input headroom on his MM phonos.
mats
I have heard something about lead sheet mats... they should be acoustically inert, and conductive too. But the downside is that lead can be poisonous.
If you are concerned about static charges -I suspect that, because of your question about a conductive mat- , some people reported good results by placing some wet sponge or similar next to the TT. It helps to drain static succesfully.
I live in a very humid location, next to -at least- 3 rivers, so static charges of the type so common in dryer climates are not a problem.
I actually use a 4 mm glass mat, ¨decorated¨ with some transparent adhesive silicone spots (very thin ones). It works well: the background of music is dark, pops are minimized, and the lp rests solidly over the spots, with no slippage (I use non-slip circular spots, of the kind used below light home appliances to avoid movement).
You must avoid to put spots in the label zone (center) and the lip zone(periphery). The disc, for what I know, should only be sustained in the recorded surface.
I have heard something about lead sheet mats... they should be acoustically inert, and conductive too. But the downside is that lead can be poisonous.
If you are concerned about static charges -I suspect that, because of your question about a conductive mat- , some people reported good results by placing some wet sponge or similar next to the TT. It helps to drain static succesfully.
I live in a very humid location, next to -at least- 3 rivers, so static charges of the type so common in dryer climates are not a problem.
I actually use a 4 mm glass mat, ¨decorated¨ with some transparent adhesive silicone spots (very thin ones). It works well: the background of music is dark, pops are minimized, and the lp rests solidly over the spots, with no slippage (I use non-slip circular spots, of the kind used below light home appliances to avoid movement).
You must avoid to put spots in the label zone (center) and the lip zone(periphery). The disc, for what I know, should only be sustained in the recorded surface.
Posts 28, 30 & 32 finally got to the heart of minimising the audibility of clicks from debris in the grooves.
Exceptional headroom in the pre stage both before, during and after the RIAA stage helps enormously.
The longer you can preserve the signal without clipping it, the less damaging you are to preserving the information near or in the click waveform. Finally let the RF filter roundoff the very fast transient that gets past all the earlier stages including your pre-amp that also requires a high headroom for this and any other clicks that come through with the signal.
30db of overload margin is about the minimum headroom that works adequately. 40db is near the maximum headroom that seems to be reported as offering benefit.
Clean or keeping clean, removes the clicks, headroom minimises audibility.
Exceptional headroom in the pre stage both before, during and after the RIAA stage helps enormously.
The longer you can preserve the signal without clipping it, the less damaging you are to preserving the information near or in the click waveform. Finally let the RF filter roundoff the very fast transient that gets past all the earlier stages including your pre-amp that also requires a high headroom for this and any other clicks that come through with the signal.
30db of overload margin is about the minimum headroom that works adequately. 40db is near the maximum headroom that seems to be reported as offering benefit.
Clean or keeping clean, removes the clicks, headroom minimises audibility.
preamp and pops minimization
Yes; as stated in the cited posts, and in AndrewT´s one, I have noticed that the RIAA preamp stage is notoriously important in impulsional noise minimization; I noticed that for the first time when I made a version of Thorsten Loesch ¨Analogue Addicts¨ phono stage (aka ¨El Cheapo¨), based on opa637 opamps.
The first thing that caught my attention when I first auditioned the unit was the lack of surface noise. In a first instance I was fooled, thinking that the preamp was somewhat ¨treble shy¨... but no: all the treble was there.
It was myself, so accustomed as I was to HF garbage (clicks, hiss and assorted nasties).
That unit is performing flawlessly since then, a couple of years ago, and nothing seems capable of uncivilize the sound quality, even very hot output cartridges (shure m44c), garage sales records and, sometimes, less than optimal styli.
Yes; as stated in the cited posts, and in AndrewT´s one, I have noticed that the RIAA preamp stage is notoriously important in impulsional noise minimization; I noticed that for the first time when I made a version of Thorsten Loesch ¨Analogue Addicts¨ phono stage (aka ¨El Cheapo¨), based on opa637 opamps.
The first thing that caught my attention when I first auditioned the unit was the lack of surface noise. In a first instance I was fooled, thinking that the preamp was somewhat ¨treble shy¨... but no: all the treble was there.
It was myself, so accustomed as I was to HF garbage (clicks, hiss and assorted nasties).
That unit is performing flawlessly since then, a couple of years ago, and nothing seems capable of uncivilize the sound quality, even very hot output cartridges (shure m44c), garage sales records and, sometimes, less than optimal styli.
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