Hi Jay,
I think Joey said he had installed a preamp,
Regards,
Nigel
On 10 Oct 2025 at 08:40, Jay Hennigan via Jukebox-list jukebox-list@lists.netlojix.com wrote:
On 10/9/25 19:01, joeymcd via Jukebox-list wrote:
I have a problem with an AMI E80 making a resonating sound while scanning. I just installed an Audio Technica AT3600 magnetic cartridge. Tied the positives together and negetives together at the cartridge. Installed an external preamp as well. Sound and tracking are good. No issues if it scans a couple selections.
Problem is when it is scanning distance it picks up a very loud resonating sound that stops immediately when the needle lands in play position. Not sure if the mute relay turns on or off in play position but when the needle lands and the click of the relay is heard the loud resonating stops immediately.
Amplifier has been rebuilt DD model previously and sounded decent with the crystal cartridge but wanted to upgrade for lighter tracking and stereo compliance. No loud resonating issue at all.
I have done this with an AMI F model with no issues. I know the F model uses an amplifier that is designed to use a magnetic cartridge but wired the cartridge the same way.
You can't directly substitute a magnetic for a crystal cartridge. The voltages and frequency response are quite different, the magnetic needs a preamplifier and equalizer. If you can find an R-145 amp that was used in the F through J it would work because that's built in to it. Or you could wire in a separate phono preamp.
What's puzzling is that the howl is only there when it's supposed to be muted. I don't see a mute relay on the R-111 amplifier schematic for the E series. There's a relay that keeps the turntable from spinning on a cold start until the 6L6s warm up, but I don't see a mute relay.
In any case you'll need to solve the incompatibility between a magnetic cartridge and a crystal input. This may fix the howl, especially if there's no muting.
-- Jay Hennigan - jay@west.net Network Engineering - CCIE #7880 503 897-8550 - WB6RDV
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