I didn't measure it, but subjectively it's very quiet. You may check this review of the original circuit (I use different parts and completely different PS): H A L L O F F A M E
It shouldn't be a problem if your amp does not amplify DC. The simplified GC does, and coupling cap might be needed with such offset values.
The offset will depend on a particular OPA637 chip; some chips will produce much less offset.
Hi guys , just completed my phonostage-measured DC offset at 15/20mV-?any problem?
It shouldn't be a problem if your amp does not amplify DC. The simplified GC does, and coupling cap might be needed with such offset values.
The offset will depend on a particular OPA637 chip; some chips will produce much less offset.
Hi Peter, plugged in it today-the transformer humming and vibrating like crazy and feel as though not enough gain( compare with herron audio phonostage-66db)
The tranny was dropped onto the floor the other day!!! Likely to be faulty.
Please advise how to wire with dual secondaries toroidal transformer. NOOB question.
Thanks.
The tranny was dropped onto the floor the other day!!! Likely to be faulty.
Please advise how to wire with dual secondaries toroidal transformer. NOOB question.
Thanks.
I'm using 2 x 12V transformer, which unloaded produce approx 14V AC per secondary.
In attached pic, you can see 4 pads (on a left). Those pads are for external transformer connection: first two from the top are for one secondary, the other two for the other secondary. You will need approx 19V after rectification and 15V regulated. If you can get 15V because of too low voltage on secondaries, settle for lower regulated voltage, it will not affect anything (adjust with changing R7 and R8)
In attached pic, you can see 4 pads (on a left). Those pads are for external transformer connection: first two from the top are for one secondary, the other two for the other secondary. You will need approx 19V after rectification and 15V regulated. If you can get 15V because of too low voltage on secondaries, settle for lower regulated voltage, it will not affect anything (adjust with changing R7 and R8)
Attachments
Here my own compilation of the complete parts list phono preamp and shunt regulator section with distributors, prices, etc...Maybe Peter can comment on its latest findings about the circuit to see if this list is still up to date. I included the omission of R7, output resistor of the preamp section.
Here my own compilation of the complete parts list phono preamp and shunt regulator section with distributors, prices, etc...Maybe Peter can comment on its latest findings about the circuit to see if this list is still up to date. I included the omission of R7, output resistor of the preamp section.
Attachments
In majority cases C4 is still needed as most LM337 types will not produce correct voltage without it: http://www.diyaudio.com/forums/audio-sector/151938-phono-stage-8.html#post2000870
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