Re: Sound Issue relating to stylus pressure/inconsistency
Posted: Sun Feb 01, 2015 9:37 am
Ok Goat, I see I'm in your crosshairs if this doesn't work out.
The cart you ordered should be fine, it's output will be a bit lower than the 400 but that may be an advantage in eliminating the need for a pot between the preamp and amp input. We'll see.
Some points here:
1) The mag cart will be a few grams heavier than the typical ceramic so you will need to adjust the lateral balance via the screw on the rear end of the arm. These arms are not well balanced to begin with and will bias either slightly upward at the start of a record, and downward toward the spiral. Do the best you can and don't worry about it. Bear in-mind that the tonearm wires will add weight if the arm is just in free space> So it is probably best to anticipate slight rebalance once it is mounted.
2) tonearm wire drees is important to reliable tracking at relatively low pressure.
3) Make sure the arm pivot bearing are neither too tight, nor sloppy. these ain't great bearing points so good enough is good enough.
4) Trip switch. On this pic you can see the trip switch and it's L-shaped keeper:
http://s1192.photobucket.com/user/Rob-N ... ort=2&o=69
The purpose of that keeper is to prevent the trip switch from loading the arm and stylus till it gets to the spiral at the end of a record. It is a significant load and a drop of light oil on the bronze switch bearing might help a bit. In the past I usually flipped the keeper out of the way and let the trip whisker ride the arm tail continuously. I then rebalanced the arm to compensate for this,
5) Long pickup wire to the preamp. You can use the existing coax lead from the arch to the preamp, however this does create a ground loop which will induce a certain amount of hum since the shield touches the arch assembly. If the hum bothers you simply run an isolated wire. You may need to run a ground wire from the preamp case to either the mech or amp chassis as you would with a turntable.
Be careful removing and replacing the flea clips of the new cart, the tiny wires can break. If they do, do not try to solder them with the clip on the cart. the plastic with deform and ruin the cart (I know).
Keep us informed.
Rob
The cart you ordered should be fine, it's output will be a bit lower than the 400 but that may be an advantage in eliminating the need for a pot between the preamp and amp input. We'll see.
Some points here:
1) The mag cart will be a few grams heavier than the typical ceramic so you will need to adjust the lateral balance via the screw on the rear end of the arm. These arms are not well balanced to begin with and will bias either slightly upward at the start of a record, and downward toward the spiral. Do the best you can and don't worry about it. Bear in-mind that the tonearm wires will add weight if the arm is just in free space> So it is probably best to anticipate slight rebalance once it is mounted.
2) tonearm wire drees is important to reliable tracking at relatively low pressure.
3) Make sure the arm pivot bearing are neither too tight, nor sloppy. these ain't great bearing points so good enough is good enough.
4) Trip switch. On this pic you can see the trip switch and it's L-shaped keeper:
http://s1192.photobucket.com/user/Rob-N ... ort=2&o=69
The purpose of that keeper is to prevent the trip switch from loading the arm and stylus till it gets to the spiral at the end of a record. It is a significant load and a drop of light oil on the bronze switch bearing might help a bit. In the past I usually flipped the keeper out of the way and let the trip whisker ride the arm tail continuously. I then rebalanced the arm to compensate for this,
5) Long pickup wire to the preamp. You can use the existing coax lead from the arch to the preamp, however this does create a ground loop which will induce a certain amount of hum since the shield touches the arch assembly. If the hum bothers you simply run an isolated wire. You may need to run a ground wire from the preamp case to either the mech or amp chassis as you would with a turntable.
Be careful removing and replacing the flea clips of the new cart, the tiny wires can break. If they do, do not try to solder them with the clip on the cart. the plastic with deform and ruin the cart (I know).
Keep us informed.
Rob
