Hi, All. Since joining the group in May, I've been reading & (hopefully) learning as much as I can. I have a Wilcox-Gay Recordio -- I deleted the crystal head, installed an Astatic magnetic head (8 ohms), and I'm running it into a Realistic 100W PA amp. I ran a Tascam 4-track into the amp in order to experiment with cutting some old band recordings. My 2nd attempt was OK -- I actually got an audible recording onto the blank! It played all the way through -- however, the volume was SO low / faint.
Thinking I might be able to boost the signal, tonight, I ran the 4-track into a Tascam mixer, then the PCM RCA out into realistic mix bus in (RCA). I could hear sound coming through the cutter head, but I wasn't able to get anything on tape. If anything, it seemed to make no difference or made it worse than it sounded during my first attempts. Tonight I couldn't get any signal to cut at all. I probably also need to adjust the counter weight (I rigged a counter weight and may have overdone it), but I'm really struggling with the challenge of getting a louder signal into the cutter head and onto a blank. Can anyone make any suggestions? Do I need a higher power amp? A higher powered mixer in between the two?
And, maybe a dumb question, but do I need to worry about frying the cutter head?
Thanks
Re: request for help - newbie with magnetic head
Hi,
You can fry the head if you feed it too much power for too long of a time. 100 watts is quite a bit of power for those old Astatic heads. They were typically run with 5 or 10 watt amps back in the day. Having more power is fine as long as you take some steps to monitor the drive level and keep the average power to the head under a few watts. Adding a fuse in series with the drive coil is a good idea. Start with a 1/4 A fast blow and move up as you gain confidence that you know what power you are hitting the head with. You should try to add some sort of voltage measurement at the head terminals or at the output of you power amp to get an handle on levels. A analog VU style metering should work well. You just need to calibrate the meter such that the 0 db represents a reasonable level. Perhaps 1 watt would be a good place to start. That corresponds to 2.83 Vac RMS for and 8 ohm head. I would start by cutting a 1khz sine wave at that level measured with a DMM and see how loud the playback is. If you have a test record with a 7 cm/sec 1Khz tone, you can compare and get an idea of how the head stacks up. If its very weak, that might indicate that the head needs work. Keep in mind that this head will not cut a commercial levels. Hope that makes sense.
Mark
You can fry the head if you feed it too much power for too long of a time. 100 watts is quite a bit of power for those old Astatic heads. They were typically run with 5 or 10 watt amps back in the day. Having more power is fine as long as you take some steps to monitor the drive level and keep the average power to the head under a few watts. Adding a fuse in series with the drive coil is a good idea. Start with a 1/4 A fast blow and move up as you gain confidence that you know what power you are hitting the head with. You should try to add some sort of voltage measurement at the head terminals or at the output of you power amp to get an handle on levels. A analog VU style metering should work well. You just need to calibrate the meter such that the 0 db represents a reasonable level. Perhaps 1 watt would be a good place to start. That corresponds to 2.83 Vac RMS for and 8 ohm head. I would start by cutting a 1khz sine wave at that level measured with a DMM and see how loud the playback is. If you have a test record with a 7 cm/sec 1Khz tone, you can compare and get an idea of how the head stacks up. If its very weak, that might indicate that the head needs work. Keep in mind that this head will not cut a commercial levels. Hope that makes sense.
Mark
Re: request for help - newbie with magnetic head
Thanks, @markrob - I really appreciate the info.