2. analog
  3. 123293-1797

Newbee help- Volume low even at full preamp volume-???

Guys- my first turntable- Dr. Feickert Firebird- arm- TTW jelco- cart Charisma MC-2: Specs-
:Cartridge Weight: 12 gCartridge Body: aluminiumCantilever: sapphireStylus: super fine line contact nude diamondVertical Tracking Angle: 20 degreesCoil: pure iron crossed-coil with single crystal high purity copperOutput Voltage: 0.42 mV at 3.54 cm/sec. Internal Impedance: 14ohmsFrequency Response: 20 –25,000 Hz ± 1 dBChannel Balance: better than 0.5 dBChannel Separation: better than30 dBDynamic Compliance: 10 um/mNRecommended Loading: 100 –1,000 ohmsRecommended Tracking Force: 2.0 g ± 0.1 gTracking Ability at 315 Hz / 2 g: 80 uMRecommended Tonearm Mass: medium
Phono preamp- Rogers PA-1A
Preamp- Wyetech ruby-
Ok- I set the Rogers Phono Pre per Charisma rec.-"We would suggest you to try the 100 Ohm and 10K Ohm of the resistive selection. Capacitance is sensitive to moving magnet cartridges, but not moving coil."

I get very low volume even with the Wyetech preamp at full volume- Please help a Newbee out- What am I doing wrong??thanks gary



fluffers
sbank's avatar
sbank
3,381 posts
 
How much gain does the Rogers phono stage put out? If I understand from above the 12AU7 puts out 50db gain, but switching to the 12AX7 results in 65db gain...correct? If so, 65db should be plenty of gain to drive the .4mv output cartridge. 
Absolutely no need to consider switching to a moving magnet! You've got a simple wiring error or a bad tube in all likelihood.

And for god's sake, never any need to turn the volume all the way up. If you pass 2:00 and it's not plenty loud, usually something is setup incorrectly.
Cheers,
Spencer
fluffers OP
78 posts
 
Thanks guys- I bought the Rogers used and the guy sent a mishmosh of sovtek tubes so I guess they are no good- 
I am going to order a new set of 12ax7- So the question is which one do you guys rec. I get- thanks again for all the help!!!
kijanki's avatar
kijanki
4,432 posts
 
65dB = 1778
0.42mV x 1778 = 0.75V

Still low - needs about 8.5dB more to get to standard 2V. Am I missing something?

fluffers OP
78 posts
 
When I spoke to the guys at Charisma they rec. 61db for the cart??
jmcgrogan2's avatar
jmcgrogan2
6,346 posts
 
According to the KAB gain calculator, 58 dB is optimum gain for 0.4 mV cartridge.
https://www.kabusa.com/pregain.htm

Keep in mind that fluffers Wytech Ruby preamp also has 12 dB of gain.
So if he has it connected correctly, and all tubes are up to spec, he should have PLENTY of gain with his 65 dB of gain using 12AX7's in his Rogers phono preamp, and the 12 additional dB of gain in his Wytech preamp.
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