Hi,
Ok, I'm calling this done and want to close out the thread by thanking everyone for their help. I attached a plot to show where I ended up. This shows the tone controls at mid, full increment, and full decrement for both the original design and with the loudness circuitry removed. This was at about 9:00 on the volume setting, but even at 12:00 the dip in the mids is still pretty pronounced.
The jukebox does sound a lot better with the loudness turned off, but it is still kinda muddy. I've been told that the Cobra system really never sounded that great and suspect this is as good as it gets. The Cobra was considered ahead of it's time in the era of 78s, but just doesn't do well with 45s - especially stereo 45s, even with the smaller diamond needles. Some people convert to magnetic carts, but this requires a lot of customization to fit to the old tonearms and get the tracking weight and shut off switch working right. Plus it requires adding a preamp and at this point you have to ask if you have not killed the soul of this jukebox. Soooo, at some point I may convert back to 78s. This particular juke was built to convert between 78s, 33-1/3 (10" only), or 45s, but clearly was best suited to 78s.
Thanks again!
Steve.
Ok, I'm calling this done and want to close out the thread by thanking everyone for their help. I attached a plot to show where I ended up. This shows the tone controls at mid, full increment, and full decrement for both the original design and with the loudness circuitry removed. This was at about 9:00 on the volume setting, but even at 12:00 the dip in the mids is still pretty pronounced.
The jukebox does sound a lot better with the loudness turned off, but it is still kinda muddy. I've been told that the Cobra system really never sounded that great and suspect this is as good as it gets. The Cobra was considered ahead of it's time in the era of 78s, but just doesn't do well with 45s - especially stereo 45s, even with the smaller diamond needles. Some people convert to magnetic carts, but this requires a lot of customization to fit to the old tonearms and get the tracking weight and shut off switch working right. Plus it requires adding a preamp and at this point you have to ask if you have not killed the soul of this jukebox. Soooo, at some point I may convert back to 78s. This particular juke was built to convert between 78s, 33-1/3 (10" only), or 45s, but clearly was best suited to 78s.
Thanks again!
Steve.
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