Shorting inputs does nothing. Bonding chassis ground to safety earth at the TT ground input does nothing.
Rails have 18mv AC.
Rails have 18mv AC.
Moved transformer to outside. Horrendous buzz sounds, worse than before.
Nothing confuses me more than phono preamps. No books seem to help me learn wtf is going on with them.
Nothing confuses me more than phono preamps. No books seem to help me learn wtf is going on with them.
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Ok so I forgot 47r R5. Put those in. With inputs shorted the noise is low, but still annoying.
With TT it was horrible because leakage from the motor went straight to the high octane. I still have safety ground tied to TT arm. I put a safety ground from wall plug to the TT motor and fixed the leakage. TT is about the same as the shorted inputs now.
I have a little noise, I am wondering if PSRR mod and maybe higher output resistors would knock it to nothing?
With TT it was horrible because leakage from the motor went straight to the high octane. I still have safety ground tied to TT arm. I put a safety ground from wall plug to the TT motor and fixed the leakage. TT is about the same as the shorted inputs now.
I have a little noise, I am wondering if PSRR mod and maybe higher output resistors would knock it to nothing?
Added 220nf across CP4. Changed sense ev to go across mosfet (watch out if you do this, mosfet pins are not ordered like circuit diagram.
Sounds good. Probably fixed bass some, like others were trying to do. Buzz is still annoying... I thought changes for that might affect PSRR could help? Maybe not. Sounds better.
Sounds good. Probably fixed bass some, like others were trying to do. Buzz is still annoying... I thought changes for that might affect PSRR could help? Maybe not. Sounds better.
Before shaking cables and stuff made sounds. Not anymore. I would like to get ride of the buzz, but already improvements are very substantial.
Again I wonder if anyone would want better boards...
Again I wonder if anyone would want better boards...
Checked transformer for leakage by reversing primary connections, no effect.
Re-isolated TT arm phono jack, no effect.
Added 10nf across output RCA for constant RF load, unsure if there's an effect.
Thinking maybe higher output resistors?
Re-isolated TT arm phono jack, no effect.
Added 10nf across output RCA for constant RF load, unsure if there's an effect.
Thinking maybe higher output resistors?
Output resistor no effect. Well on the extra sound I don't like when nothing is playing... I put in 680r and removed 10nf caps. 680r might be high, it's just what I had laying around in RN's. It actually sounds really nice with them. It's more musical. But I need to see if ambiance and such of the venue was quelched maybe by some HF loss... not sure.
It kinda sounds when you have an open input, when the volume is higher. Maybe it is just PSRR...
It kinda sounds when you have an open input, when the volume is higher. Maybe it is just PSRR...
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Bleh, I happened to find my transformer is making the noise that seems to make it to speakers. Wonderful. Hammond 229 usually doesn’t do me wrong like that. But they are matching sounds... I guess I can order an Antek.
On another note I disabled the opamp for fun. Sounds better. I don’t think it does any good, like it only hurts it. Moving sense ev helped, this was superior. Just cut the zener. But if you’re running an SMPS you might not like it as much. I put an inductor in the DC input path to reduce noise - works good.
On another note I disabled the opamp for fun. Sounds better. I don’t think it does any good, like it only hurts it. Moving sense ev helped, this was superior. Just cut the zener. But if you’re running an SMPS you might not like it as much. I put an inductor in the DC input path to reduce noise - works good.
Hi and Merry Christmas at all,
after a long reading of this post, i'd like to buy a pcb if and when available.
after a long reading of this post, i'd like to buy a pcb if and when available.
@ Sharif,
In post 292
https://www.diyaudio.com/community/threads/the-high-octane-phono-preamp.242387/page-15
you refer to a simulation. Can you - or someone who has saved the file - please re-post?
Or even better: has someone experimented in the meantime with the alternative setup of Sharif, or the one of Abraxalito in post 290?
In post 292
https://www.diyaudio.com/community/threads/the-high-octane-phono-preamp.242387/page-15
you refer to a simulation. Can you - or someone who has saved the file - please re-post?
Or even better: has someone experimented in the meantime with the alternative setup of Sharif, or the one of Abraxalito in post 290?