Same set up as before except with 2 12v batteries in series.
The cap multiplier and cascode NPN transistors are very quiet.
The KA7815 also looks quiet as well.
The noise floor is ~10dB higher with the batteries. Needs a closer look see as to why. Edit: see the added corrected plot below.
looks like the power cords need to be shielded.
Leakage is still unknown.
Thanks DT
Oops I used the wrong Bandwidth
this is the corrected one
The cap multiplier and cascode NPN transistors are very quiet.
The KA7815 also looks quiet as well.
The noise floor is ~10dB higher with the batteries. Needs a closer look see as to why. Edit: see the added corrected plot below.
looks like the power cords need to be shielded.
Leakage is still unknown.
Thanks DT
Oops I used the wrong Bandwidth
this is the corrected one
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Hello DualTriode,
I have also built a MM-phonopre with battery-PSU (2 x 12 V Panasonic Gelcells). The batteries are in series, so 24 V DC. It is not a Pearl. I've got very good results (noise and sound).
Your measurement in #927 is done with batteries? Where does that 60Hz-peak come from?
Could be from a PSU in the measurement setup? Below -140dB is extremely low noise - I would say.
Cheers
Dirk
I have also built a MM-phonopre with battery-PSU (2 x 12 V Panasonic Gelcells). The batteries are in series, so 24 V DC. It is not a Pearl. I've got very good results (noise and sound).
Your measurement in #927 is done with batteries? Where does that 60Hz-peak come from?
Could be from a PSU in the measurement setup? Below -140dB is extremely low noise - I would say.
Cheers
Dirk
Attachments
Hey Dirk, Nice work.
The measurement in post 927 is with 2 12volt batteries in series followed by a KA7815 regulator into a breadboard of the P3 input stage with a 1K resistor in place where the jfets would be. The output to the analyzer input is at the collector of Q5.
This plot is a peak at the noise level of the P3 input stage.
Next is to inject ripple across the BW to measure PSRR.
The spike at 60Hz is likely do to leakage, with the analyzer input shorted the 60Hz "peek" is all but absent.
Thanks DT
The measurement in post 927 is with 2 12volt batteries in series followed by a KA7815 regulator into a breadboard of the P3 input stage with a 1K resistor in place where the jfets would be. The output to the analyzer input is at the collector of Q5.
This plot is a peak at the noise level of the P3 input stage.
Next is to inject ripple across the BW to measure PSRR.
The spike at 60Hz is likely do to leakage, with the analyzer input shorted the 60Hz "peek" is all but absent.
Thanks DT
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It's only a matter of time until someone deploys four 12V sealed lead acid batteries to give "raw" ±24 volt supplies, then connects a UDP3 filter board between the batteries and a Pearl 3 phonostage. Batteries ---> UDP3 filter ---> Pearl 3. UDP3 includes four heatsinks and it can comfortably drop ±24V to ±19V_approx while running cool.
Why would anyone do such a thing? Maybe, because it seems like a lot of fun; AND because it completely isolates Pearl 3 from the AC mains; AND because it also yields an even lower noise supply. Batteries are a lot quieter at 2xFmains than the transformer + rectifiers + filter capacitors on UDP3, after all.
If they put the batteries in a separate chassis, Pearl 3 becomes a three chassis phonostage: batteries; supply filter ; phono amplification. It might allow the builder to include recharging circuitry (with double or triple relay isolation) in the third chassis. The recharge contrivances could run from a pair of DC wall warts if desired; then all three chassis would be completely isolated from the AC mains -- including the rechargeable battery box.
Why would anyone do such a thing? Maybe, because it seems like a lot of fun; AND because it completely isolates Pearl 3 from the AC mains; AND because it also yields an even lower noise supply. Batteries are a lot quieter at 2xFmains than the transformer + rectifiers + filter capacitors on UDP3, after all.
If they put the batteries in a separate chassis, Pearl 3 becomes a three chassis phonostage: batteries; supply filter ; phono amplification. It might allow the builder to include recharging circuitry (with double or triple relay isolation) in the third chassis. The recharge contrivances could run from a pair of DC wall warts if desired; then all three chassis would be completely isolated from the AC mains -- including the rechargeable battery box.
I am glad you raised the question, Mark. I had a suspicion it was only a simulation schematic, and probably should not have posted it, but I did state it was in development. It should still be on-topic as a viable example of an alternative approach to regulation, since several ideas were being discussed here.
Wyn's response to me:
"R136 is not a real resistor. It's there to help model the wall wart. Without it the simulation has convergence difficulties.
No-one should be attempting to produce a layout worthy schematic from the posted simulation schematics."
Bottom line - as with so many developing schematics here, wait for the final product if you are interested in building it.
If anyone finds post #937 mystifying, it is an oblique reference to (this post) in which I confessed to extreme caution / lack of bravery, when AC mains connections are not fully insulated.
I think you mean Mark.
I’m Jim.
Howdy Fred.
Well, looks like today I'm gonna be able to do some listening... all of these people measuring and not listening it's sort backwards.
After the flu, building contractors, Macho Smoke and tooth pulling it's been hectic. I've had like only four hours of P3 listening with the default op-amps that came with it ( I need to figure them out ). I got the Burson v6 and v6 Vivid dual opamps at hand. But, I think I'll do some listening for a while as it is before I start rolling.
I've noticed that not only is the DIYstore AND Burson itself don't have the v6 classic opamps... and if you read into Burson's products there's a new V7 Pro Vivid opamp... but it's only available in some of their products, not as a stand alone part per se...
What other op-amps can you suggest?
BTW- my P3 is set up with 55db gain, 47K load and no capacitance. The cartridge is a Grado Master 2. ( 1 mV output, moving iron ).
Time to warm up the system. 🎶
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No worries, @tonyEE - our listening to measuring ratio is easily 10X, hence my post about the audible differences between the two op amps I've tried so far.
I've got NE5532, TLE072, and a few others, but I'd rather continue to enjoy the listening than open up the box and switch op amps right now.
I've got NE5532, TLE072, and a few others, but I'd rather continue to enjoy the listening than open up the box and switch op amps right now.
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