Hi
I've been lurking for a while and I've got a Atom (Vanrock) A-101 (e-101) suitcase cutter which was in non-working condition. Can now cut good looking grooves but having a problem with noise.
Tried a couple of things to reduce surface noise including heating, anti static and replaced stylus. Still very noisy.
Then realised that there was a lot of hiss on the amplifier, checked with a cup on the stylus and sure enough it's coming through.. I know very little about transistor amps, so where to start trying to make this less noisy?
Many thanks for any help
Re: Hi and any pointers for starting out with a transistor a
Hi,
Before you go to that trouble, try disconnecting the amp from the head before you cut your silent grooves. Compare the playback noise floor before and after and see if there is any benefit to using a different amp.
Mark
Before you go to that trouble, try disconnecting the amp from the head before you cut your silent grooves. Compare the playback noise floor before and after and see if there is any benefit to using a different amp.
Mark
Re: Hi and any pointers for starting out with a transistor a
Hi Mark
Thanks so much for the reply, I'd actually reached the same conclusion so it's on my to do for today to try to rule out poor cutting practice
Also want to potentially cut with another amp but can't find information about the rating of the amp/cutterhead other than power consumption of the unit as a whole at 34W - any ideas of how I'd find this out so I don't blow the head/give it enough juice?
Cheers
D
Thanks so much for the reply, I'd actually reached the same conclusion so it's on my to do for today to try to rule out poor cutting practice
Also want to potentially cut with another amp but can't find information about the rating of the amp/cutterhead other than power consumption of the unit as a whole at 34W - any ideas of how I'd find this out so I don't blow the head/give it enough juice?
Cheers
D
Re: Hi and any pointers for starting out with a transistor a
Hi,
As far as power goes, you can get feel for the need by the mains rating, but having more power reserve up to a point is not a bad thing. If you go with a 50-100 watt amplifier, you should be in good shape. I don't know the particulars on the Atom. Is the head a moving iron or moving coil design? Is it 8 ohms, 16, or some other impedance? You could make measurements of the head to determine the impedance. The easiest approach would be to measure the DC resistance of the head and double that number as a decent approximation. An 8 ohm head measures 4 ohms DC, for example. To get an idea on the Atom power amp, connect an 8 ohm resistor as a load (use a 50 watt rating) to the Atom amp in place of the head and run a 1 Khz test tone into the unit. Measure the AC voltage across the load resistor as you increase the signal level. At some point you will not be able to see an increase in voltage as you drive amp into clipping. Use that number to determine the on board amplifier power rating (Power = Voltage squared divided by 8 ohms). Going with an amp with twice that rating would not be a bad thing. In any event, the head only requires a few watts on average to do its work. You need power reserve to handle high frequency short duration peaks. Using a higher powered amp gives that reserve, but you will never use anywhere close to that on average or you will damage the head. Adding a fuse in line with the head can help protect the it against the use of too much power. A 1/4 amp fast blow fuse would be a good place to start. If that tends to blow too easily, you can always increase the value. I would suspect that the head will saturate and distort long before you get into a dangerous zone as far as power is concerned. So as you gain experience, you should be able to determine if you are running too hot.
Mark
As far as power goes, you can get feel for the need by the mains rating, but having more power reserve up to a point is not a bad thing. If you go with a 50-100 watt amplifier, you should be in good shape. I don't know the particulars on the Atom. Is the head a moving iron or moving coil design? Is it 8 ohms, 16, or some other impedance? You could make measurements of the head to determine the impedance. The easiest approach would be to measure the DC resistance of the head and double that number as a decent approximation. An 8 ohm head measures 4 ohms DC, for example. To get an idea on the Atom power amp, connect an 8 ohm resistor as a load (use a 50 watt rating) to the Atom amp in place of the head and run a 1 Khz test tone into the unit. Measure the AC voltage across the load resistor as you increase the signal level. At some point you will not be able to see an increase in voltage as you drive amp into clipping. Use that number to determine the on board amplifier power rating (Power = Voltage squared divided by 8 ohms). Going with an amp with twice that rating would not be a bad thing. In any event, the head only requires a few watts on average to do its work. You need power reserve to handle high frequency short duration peaks. Using a higher powered amp gives that reserve, but you will never use anywhere close to that on average or you will damage the head. Adding a fuse in line with the head can help protect the it against the use of too much power. A 1/4 amp fast blow fuse would be a good place to start. If that tends to blow too easily, you can always increase the value. I would suspect that the head will saturate and distort long before you get into a dangerous zone as far as power is concerned. So as you gain experience, you should be able to determine if you are running too hot.
Mark
Re: Hi and any pointers for starting out with a transistor a
Ah great, thanks so much, really helpful. I'll follow and measure and consider the fuse as a safety.
As for whether it's moving coil or iron, I'm unsure - wasn't super keen on taking the head apart to check and also how to tell either way
Before I read your reply I carefully ran a signal into the head and successfully cut with considerably less noise (still some surface), so am now convinced that the hiss on the amp is transferring to the record and distorting the cut so this work around is working for now but I really need to find a way to lower the noise on the amp if anyone has any pointers on where to start that would be amazing. No obvious defects on caps but haven't started measuring anything yet.
As for whether it's moving coil or iron, I'm unsure - wasn't super keen on taking the head apart to check and also how to tell either way
Before I read your reply I carefully ran a signal into the head and successfully cut with considerably less noise (still some surface), so am now convinced that the hiss on the amp is transferring to the record and distorting the cut so this work around is working for now but I really need to find a way to lower the noise on the amp if anyone has any pointers on where to start that would be amazing. No obvious defects on caps but haven't started measuring anything yet.