Over the years I picked up 78s that I thought were cool or interesting with the hopes that down the line I would have a system to play them on. I figured i would mount a 78 cart on an AT-120 and live with the built-in RIAA curve of my phono pre-amp. Fast forward to now and I recently found a nice Dual 1214 which plays at 78. Then I found a Bell 2200C mono amp which has a heap of phono EQ settings in addition to RIAA. My first thought was to purchase and mount a 78 cart and hook up an extra speaker to the amp and I'm all set .... but as I started researching carts, I realized it's not that simple. The modern 78 carts are wired mono but are designed to be mounted on turntables with stereo outputs. The Bell uses a single phono input (it actually has 3 inputs - MAG 1, MAG 2 and CRYSTAL) My natural instinct is to use a Y cable or a summing box .... but I believe that would boost the signal and overdrive the input (plus there is no point in summing 2 parallel mono signals, I would love to avoid unnecessary steps in the chain.) That brings me to the conclusion of using only 1 single RCA cable, that should do the trick.
Here is the math: For the sake of example, if I use an AT-VM95SP cart on the Dual, it's rated output is 2.7 mV (1 kHz, 5 cm/sec.) and it's recommended load impedance is 47KΩ .... since those #s are based on a parallel output, would you split the total voltage and ohms in half for the signal coming through 1 channel of the RCA? Which input on the amp would you match it to? The Mag 1 input is rated for 30 millivolts or higher with a load resistor set at 27.000 ohms. The Mag 2 is rated for approximately 10 millivolts and the load resistor is 47,000 ohms. Obviously, crystal isn't an option. I'm not tied to the AT cart, I'm just putting it out there as an example. Any recommendations on a cart or specs that can be a better match would certainly be appreciated.
Thanks for reading all of this! Everything I search about Y cables is about splitting a single output to dual inputs, not the other way around.
Here is the math: For the sake of example, if I use an AT-VM95SP cart on the Dual, it's rated output is 2.7 mV (1 kHz, 5 cm/sec.) and it's recommended load impedance is 47KΩ .... since those #s are based on a parallel output, would you split the total voltage and ohms in half for the signal coming through 1 channel of the RCA? Which input on the amp would you match it to? The Mag 1 input is rated for 30 millivolts or higher with a load resistor set at 27.000 ohms. The Mag 2 is rated for approximately 10 millivolts and the load resistor is 47,000 ohms. Obviously, crystal isn't an option. I'm not tied to the AT cart, I'm just putting it out there as an example. Any recommendations on a cart or specs that can be a better match would certainly be appreciated.
Thanks for reading all of this! Everything I search about Y cables is about splitting a single output to dual inputs, not the other way around.
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If the cartridge is truly wired mono (L and R connected together internally) then just use either one of the RCA plugs
into the Bell's single RCA jack. But the AT is NOT wired as mono, although you can still use only one RCA plug into MAG2-47k.
You could try a Y connector as well, to use both plugs into MAG2 and see how it works out. Some records may have less noise with both plugs, and some may have less noise with only one of the plugs. You would have to find the quieter plug by trial.
MAG1 does not have enough gain and would be noisy.
AT:
"This VM95 Series cartridge with 3.0 mil conical stylus fits half-inch mount turntables. While this cartridge is designed to play 78 RPM mono records, it is, nevertheless, a stereo cartridge, allowing users to choose between the left and right channels, which can be especially helpful in archiving applications to minimize noise and distortion."
into the Bell's single RCA jack. But the AT is NOT wired as mono, although you can still use only one RCA plug into MAG2-47k.
You could try a Y connector as well, to use both plugs into MAG2 and see how it works out. Some records may have less noise with both plugs, and some may have less noise with only one of the plugs. You would have to find the quieter plug by trial.
MAG1 does not have enough gain and would be noisy.
AT:
"This VM95 Series cartridge with 3.0 mil conical stylus fits half-inch mount turntables. While this cartridge is designed to play 78 RPM mono records, it is, nevertheless, a stereo cartridge, allowing users to choose between the left and right channels, which can be especially helpful in archiving applications to minimize noise and distortion."
Thanks, Rayma! I don't know why I chose the AT, I'm leaning towards the Grado 78E. I have an Ortofon mono cart in my main system (2M mono SE) that is true mono, it was wishful thinking these 78 carts were too.
I think the AT is a stereo stylus with a diamond shape and size for 78 records.
This is fine, since there will be less record wear.
From my experience playing mono 33 records, playing them in stereo has the effect of the music being centered,
and the noise located at each speaker (each channel has different noise). This audibly separates out
the music from the noise, and you can hear the music more clearly with less masking by the noise.
I would think a similar thing happens with the mono 78s when using a stereo 78 stylus, and playing in stereo.
But you have to try to ignore the two noise sources flanking the music.
This is fine, since there will be less record wear.
From my experience playing mono 33 records, playing them in stereo has the effect of the music being centered,
and the noise located at each speaker (each channel has different noise). This audibly separates out
the music from the noise, and you can hear the music more clearly with less masking by the noise.
I would think a similar thing happens with the mono 78s when using a stereo 78 stylus, and playing in stereo.
But you have to try to ignore the two noise sources flanking the music.
I have found that when using my mono cart for mono 33s, the noise is significantly diminished. It's very different than using the stereo cart on the same albums which can give a sense of stereo. One day I will make a video with my Little Richard album using both my mono and stereo carts. In stereo it is unlistenable, in mono it really shines.... hard to believe that it is the same record!
I never would have considered any of this and would have been caught off guard by it all. The Y adapter would likely be my first response in this case.