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Sansui 8080db phono question

L

ltup337

New Member
Hello,
I recently acquired a Marantz 6300 TT and hooked it up to my 8080db. It sounds great but the gain is very low - I have to crank it all the way up to get it to a decent volume. Does anyone know if a phono preamp is required or if i have an issue with the 8080db phono stage? As I have never used this TT or the phono stage on 8080db I am trying to isolate the problem before buying a phono pre.

Thanks in advance.

-Lee
 
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Hei.
Not knowing what type of pickup / cartridge you have, I would check that first. The phono input is designed for MM (Moving Magnet).

:) Stig
 
TR-2075 said:
Hei.
Not knowing what type of pickup / cartridge you have, I would check that first. The phono input is designed for MM (Moving Magnet).
Click to expand...

What he said. If you've got a moving coil cartridge, they put out <5mV vs. a moving magnet which might put out 150mV. BIG DIFFERENCE. A MC phono amplifier has an additional gain stage to get the signal level up before feeding it to the MM amplifier.
 
I bought the AT440MLa cartridge after reading some good reviews on it. I see that it is a moving magnet so it sounds like there may be an issue with the cartridge. I seriously have to turn it all the way up to get just a normal listening level - with that comes hiss.
 
So I looked at the specs of the cartridge and even though it is a MM cartridge, the output seems low based on your comments above. Sounds like i need a pre-amp? Any recommendations for a low cost high performer (which is how the AT cartridge is classified)?

audio-technica AT440MLa Specifications

Output voltage at 1000 Hz, 5cm/sec. ------> 4.0mV

thanks for the quick replies!

-Lee
 
If the cartridge is new and the amp is old, I'd bet my money on the phono stage, especially given that cartridges don't induce hiss. What you're likely hearing is the background noise floor being amplified. The S/N ratio on average phono preamps is in the 70-80dB range. As either the signal is too low or there's a gain stage issue, the noise amplitude is approaching that of the signal.

If this is happening in both channels, I'd look at the power rail feeding the phono preamp... often there's a few 3-pin regulators used to generate separate voltages for the tuner sections(s), preamp, and phono preamp. They're easy to identify and easy to test, but BE CAREFUL with your test leads. They're generally a TO-220 package, often on a small-ish heatsink in the power supply section (near the big filter caps). Not knowing your specific amp, you're likely to see 78xx series positive regs and 79xx series negative regs. You'll have to look up the datasheet once you identify the part number for the pinout... common ones would be 7815 (+15V), 7812 (+12V), 7905 (-5V) you get the picture.

Dave
 
me again, got some more advice about this cartridge. sounds like i don't have the stylus assembly "snapped in" tight. i am told that also produces a low output and i really think this is my prob. thanks again.
 
You are probably right.
Just checked my Shure witch is 5 mV, so AT’s 4 mV should do it.
I have seen similar symptoms when the wiring has been connected wrong.
 
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