Ikoflexer,
I have had 1.1uF MKP at Vref only. It sounds good with my opa627 buffer.
To get lower impedance at lower frequencies I have just added a brand new 220uF/16V Rubycon ZA in parallel to the Vref 1.1uF for a try. Whether it sounds better or not I can't really tell yet, but definitely not worse, considering the electrolytic cap needs some run-in. Maybe the 103dB - 120dB PSSR below 1kHz of the opa627 is effective so that a lower impedance at this region has little effect. From the similation you sent me, the 1.1uF is good above 1kHz.
The price to pay for adding more capacitance is the much longer time it takes to reach the desired rail voltage after turn-on. The voltage was set to 12V, it took a good 10 minutes to reach 11V. With 1.1uF, it took no time.
I think it would be good if you could post your simulations of the impedance plots (in ohms please, not dB for easy reading, as we are more used to ohms) with a few capacitor values, such as 1.1uF, 22uF, 47uF and 100uF. Given the slow charging up of the capacitor due to the low current of the J201, I would not think I would use anything above 100uF.
Your graphs will help us to decide what values to use for the Vref cap.
Thanks,
Bill
I have had 1.1uF MKP at Vref only. It sounds good with my opa627 buffer.
To get lower impedance at lower frequencies I have just added a brand new 220uF/16V Rubycon ZA in parallel to the Vref 1.1uF for a try. Whether it sounds better or not I can't really tell yet, but definitely not worse, considering the electrolytic cap needs some run-in. Maybe the 103dB - 120dB PSSR below 1kHz of the opa627 is effective so that a lower impedance at this region has little effect. From the similation you sent me, the 1.1uF is good above 1kHz.
The price to pay for adding more capacitance is the much longer time it takes to reach the desired rail voltage after turn-on. The voltage was set to 12V, it took a good 10 minutes to reach 11V. With 1.1uF, it took no time.
I think it would be good if you could post your simulations of the impedance plots (in ohms please, not dB for easy reading, as we are more used to ohms) with a few capacitor values, such as 1.1uF, 22uF, 47uF and 100uF. Given the slow charging up of the capacitor due to the low current of the J201, I would not think I would use anything above 100uF.
Your graphs will help us to decide what values to use for the Vref cap.
Thanks,
Bill
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OK Bill, I'll post those plots soon. Indeed, I would find such a slow turn-on time unacceptable too.
At least some of you are listening to something! I've disassembled all my amps months ago with big plans to shuntify everything and now months later I'm still listening to commercial jvc piece of junk 🙁( I miss my headphone amp sniff sniff
Hi, guys,
I am doing some tunning today. I had 2.2uF MKP || 100uF/25V Rubycon ZA as the output cap. Replaced the 100uF with 470uF/25V Rubycon ZL. It did not sound as good as the 100uF ZA. So the 100uF back on.
People reported that large caps slow the music. I never believe that. But in this particular case, the 100uF ZA (impedance at 100kHz: 0.078R) betters the 470uF ZL (impedance at 100kHz: 0.038R).
Have not tried other values but am very content with the 100uF ZA.
Regards,
Bill
I am doing some tunning today. I had 2.2uF MKP || 100uF/25V Rubycon ZA as the output cap. Replaced the 100uF with 470uF/25V Rubycon ZL. It did not sound as good as the 100uF ZA. So the 100uF back on.
People reported that large caps slow the music. I never believe that. But in this particular case, the 100uF ZA (impedance at 100kHz: 0.078R) betters the 470uF ZL (impedance at 100kHz: 0.038R).
Have not tried other values but am very content with the 100uF ZA.
Regards,
Bill
The music is good...🙂
I highly recommend this, it is a treasure, if you are into classical music:
Harp Concertos, Handel, Boieldieu, Dittersdorf
Marisa Robles
The Academy of St. Martin-in-the-Fields, Iona Brown
Decca 425 723-2
Especially track 10 - 12 harp solos. Track 10 of Mozart: Theme, Variations and Rondo pastorale, is really breathtaking. The performance and music are first class.
If you system is up to a certain level, the subtle but also dynamic harmonics of the vibrations of the harp would make you feel like sitting in a concert room. But be warned - I used to listen to this piece at a lesser system and the music was not as lovely as it is now.
I highly recommend this, it is a treasure, if you are into classical music:
Harp Concertos, Handel, Boieldieu, Dittersdorf
Marisa Robles
The Academy of St. Martin-in-the-Fields, Iona Brown
Decca 425 723-2
Especially track 10 - 12 harp solos. Track 10 of Mozart: Theme, Variations and Rondo pastorale, is really breathtaking. The performance and music are first class.
If you system is up to a certain level, the subtle but also dynamic harmonics of the vibrations of the harp would make you feel like sitting in a concert room. But be warned - I used to listen to this piece at a lesser system and the music was not as lovely as it is now.
😕
Did Iko say that the regulator does not care about how big a cap behind it?
Does even 100uF alter the gain curve VS frequency big time...?
I compared 2.2uF MKP only and with added 100uF, the later sounds smoother.
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I don't know how it takes it, but 100 to 470 must be doing more than cap quality and helping something parameter-wise or not.
It certainly does not bother it else it would duck down the output voltage and get hot oscillating. But any drastic termination capacitor value upwards change must cut gain progressively lower in frequency. I see 4uF C1 on the cct. But it has so strong gain that can spare some, and something must be working better for you. Maybe less noise higher.
Alright, I will check it again.
Worked passed midnight last night designing the circuit board for my tweeter power amp, quite complicated but can be done.
Time to have a short nap
😴😴😴
Worked passed midnight last night designing the circuit board for my tweeter power amp, quite complicated but can be done.
Time to have a short nap
😴😴😴
If 100uF termination works better for you than low uF when on your particular load why change? The reg does not bother becoming unstable, so all well. All I am saying is don't think that the cap quality between 100 and 470 mattered most than what you have done to the curve when exchanging them. If it was the quality only, then the small PP would do better. But its the tech as a system that matters most. Its good the reg don't bother.
You are right, of course. I was not referring to cap quality, but cap value uF.
Tried 2.2uF MKP || 6 x 2.2uF MKT and did not like it. Better 2.2uF MKP || 100uF electrolytic.
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