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Old 1st November 2009, 05:22 PM   #71
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Quote:
Originally Posted by 04dgmsilv View Post
Still need to play around a bit to see if I can minimize some hum.
If you are using only the filter caps on phonoboard, see if adding C11/C12 on PS board helps.

BTW, stand alone PS board will not work properly without C11/C12: those caps are needed there to get the voltage right.
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Last edited by Peter Daniel; 1st November 2009 at 05:35 PM.
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Old 2nd November 2009, 01:34 PM   #72
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Thanks for the update Peter, I will play around with the output resistor after things are sufficiently broken in.

The PS board is separate from the phono circuit board, so I am using both sets of caps. With my Pearl MM/MC Phono, I had hum due to the proximity of the Hammond split bobbin xfmr to the audio circuit. I had to physically move the xfmr to a separate enclosure, I'm hoping that is not the case here as this is one of the first of these split bobbin xfmrs that does not buzz like crazy. I will have to fiddle around with that to see what my options are.

The other aspect I need to look at is whether or not to ground the tonearm to the phono circuit ground, right now the ground is floating.
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Old 2nd November 2009, 04:54 PM   #73
toufu is offline toufu  United States
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Hi Peter, I found my problem which was a bad connection to the audio jacks.

Now I have sound coming out, but I used an MM cartridge and I get very low gain and muffed sound? I would think it would put out a lot of gain fro MM cartridge.

I tried to install my Zu Denon 103 on to test but accidently dropped it and destroyed the cantalever! Doh! So now I have no more MC cartridges to test it with.

Can somebody with an MM cartridge and this phono amp do a test to see if the gain is indeed low for MM cartridges? Thanks.
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Old 2nd November 2009, 04:57 PM   #74
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Quote:
Originally Posted by toufu View Post
Can somebody with an MM cartridge and this phono amp do a test to see if the gain is indeed low for MM cartridges? Thanks.
It's usually house cleaners that kill cartridges.

The gain is based on internal impedance of your cartridge...maybe your MM is very high impedance?
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Old 2nd November 2009, 05:58 PM   #75
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"The output level is determined by the output amperage of the cartridge (output voltage divided by internal impedance)"
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Old 2nd November 2009, 06:00 PM   #76
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forgot about that part of the equation. sorry,
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Old 2nd November 2009, 06:15 PM   #77
toufu is offline toufu  United States
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My cartridge is an Sumiko Antante P-76. It's got output of 2.5mv, output impedance of 1.7k ohm and load impedance of 47k ohm. What do you guys think?
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Old 2nd November 2009, 06:46 PM   #78
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I'm using Shelter 901 which has 0.4mV output and 12 ohm resistance; that produces 0.033mA output and is fine with 6dB gain line stage into F5 amp.

By comparison, your cartridge would produce 0.0015mA output, which is about 27dB less.
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Old 2nd November 2009, 07:43 PM   #79
le´flu is offline le´flu  Germany
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Hi Peter,
PhonoPre is running with Denon DL103 as well as with Lyra Dorian
without any hum etc. And the PCB is still not built in housing ;-)
How to connect the tonearm-ground? Directly soldered to ground
between BGStd 100???

The sound is great, and it´s even getting better....at the beginning
the heights where quite agressive.

Greetings Ulf

P.S. what kind of preamp do you use? you wrote about 6db amplifi-
cation.
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Old 2nd November 2009, 08:40 PM   #80
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Quote:
Originally Posted by le´flu View Post
How to connect the tonearm-ground? Directly soldered to ground between BGStd 100???
I guess that would work best.

I'm using this preamp: 6moons audio reviews: AudioZone PRE-T1
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