Tube Phono Stage MC MM not happy with the loudness of the MM

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stump

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Specs of my Phono are below.I run MC cart turntable and a MM cart turntable out the same Tube Phono.The loudness of the MC is just above my regular volume.The loudness of the MM and Amp at maximum is well below my regular volume. Swapping out the Tube Phono with a borrowed solid state phono the MC and MM carts even at low volume nearly blew my speakers.I don't expect the Carts are the issue. Anyone who knows DIY Tube Phono can a part be swapped out to increase the gain on the MM ??
Thanks
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Line Magnetic Audio Analog Sound AS-129P RIAA LP MM/MC VALVE PHONO STAGE

Specification
Input impedance: 100KΩ / 600Ω
PHONO EQ: RIAA, COL, NAB, FFRR, AES, LP
Output impedance: 600Ω
Sensitivity: 1V
Gain: 9.6dB
Signal to noise ratio:> 90dB
Frequency response: 10Hz ~ 20KHz ± 3dB
Total harmonic distortion: 0.3%
Volume: (W * H * D) 450 * 200 * 500 mm
Net Weight: 22Kg
Gross Weight: 24Kg
Power supply: AC 220V (+-5%) (50Hz)
working conditions: temperature 0℃~40℃ Moisture: 20% ~ 80%
storage conditions: temperature: - 20℃~70℃ Moisture: 20% ~ 90%
 

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How can a phono stage only have 9.6dB of gain? Is that a mistake in the specifications?
 
mep said:
How can a phono stage only have 9.6dB of gain? Is that a mistake in the specifications?
Click to expand...

Thats what my friend said yesterday! My guess is it was made from the 1940s topology of the Western Electric to work with Horn Speakers.
 
Assuming that weird 9.6dB gain listed is a misprint - sounds like it could be a loading / impedance mismatch issue. Is your loading set to the 600 ohm or 100K ohms position (listed in specs)? Or is that even a user choice? 600 ohms is fine for most MC cartridges, but no bueno for an MM with a lot of (non-moving) coil that's expecting to see 47K - you could lose a LOT of signal from the resulting voltage divider. 100K should work fine with an MM. I'd try to verify what impedance the MM cart is seeing right now.

Man, that amp has a cool aesthetic. Hope you figure out the MM side!
 
First I suspect the 9.6 db gain is that amount over the gain of the MM section whatever that is. The 100/600 ohm choice is for when the switch on the back is flipped to the MC position and the MM switch position is probably 47 kohm as standard. The volume difference is due to the output voltages of the two cartridges being used if the MC cartridge has higher than normal output and the MM has lower than standard output like some of the early Grado's. What us the gain of the preamp in the MM position and what are the two cartridges? They are never going to be the same.
 
Jack said:
First I suspect the 9.6 db gain is that amount over the gain of the MM section whatever that is. The 100/600 ohm choice is for when the switch on the back is flipped to the MC position and the MM switch position is probably 47 kohm as standard. The volume difference is due to the output voltages of the two cartridges being used if the MC cartridge has higher than normal output and the MM has lower than standard output like some of the early Grado's. What us the gain of the preamp in the MM position and what are the two cartridges? They are never going to be the same.
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MC cart is Clearaudio MC da Vinci V2 and the MM is Soundsmith Carman Mk 2 (moving Iron).Both carts volume output is much lower then if using a Solid State Phono .The only adjustment I have is the black knob .For MC it is Full then I back off so the needle gauge red lines.For MM it is turned full and the needle is low with some records barely reaching quarter way let along red line.
Later when I get my Horn speakers the Clearaudio TT will be moved and have its own Solid State Phono .The MM will be part of a full tube system.
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At .6 the MC is on the higher end for MC output and at just over 2 volts the MM is on the low end for MM cartridges which are generally in the 3.5 volt range.
 
If that phono pre really only has 9.6dB of gain, it’s a miracle you can hear music at all.
 
I'm not familiar with your phonostage but if possible, try a quick test.

First: Try removing the MC cartridge RCA tonearm cable connectors from the unit and just run it with the MM cartridge on the MM RCA connection input. If the signal level of the MM cartridge connection increases, the phonostage may not like both cartridges connected simultaneously.

Second: Try removing the MM cartridge RCA tonearm cable connectors from the unit and just run it with the MC cartridge on the MC RCA connection input. If the signal leve of the MC cartridge connection increases, the phonostage may not like both cartridges connected simultaneously.

If both cases are true, the unit may not be situated for both MM and MC inputs to be connected at the same time.

As mentioned above, I'm not familiar with the phonostage but with the limited information I have seen, this test is worth a try.

Dre
 
I will defer to Dre every time when it comes to trouble shooting, his input is always tactful and objective.

my two cents--and don't take this the wrong way--im not slagging Stump's system or choices in gear. From my experience with WE reproductions and similar gear based on designs from the '30s-40s you cant stray from the WE system approach. Their components are gain matched with speakers >100 db of sensitivity and amplifiers with very high input sensitivity (by today's standards). You insert a single component based on a vintage WE design into a 'modern' system and you will have gain miss matches all over the place. 9.6 db of phono gain by yesteryear's standard is not compatible today. The AS-129P has SUTs and its still shy in gain, that should tell you something.
 
Thanks Dre ,I have given your suggestion a try but made no difference.Puroagave can I add a SUT? What you have said is %100 given my situation.Before I bought this Phono I discussed with the dealer the gain was too low.He also agreed it was too low and he put the question to the manufacture and they came back saying similar to your quote "WE reproductions and similar gear based on designs from the '30s-40s you cant stray from the WE system approach." I still went ahead with the buy as I am putting together a complete Line magnetic retro system which will have the Horn speakers >100 db.
My original question was if it was a simple mod to increase gain! If not once it is set up with the horn speakers it should be loud enough...
Thanks for the input..
 
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