The new Grado Sonata has .5 mV and 2 Ohms but the L is still 2mH. Some of the virtual ground input preamps will yield a time constant in the audio band based only on the cartridge characteristics. A Denon 103 for instance is 160 Ohms and 380uH. If you assume 2 Ohms and run a hot bipolar input the current noise will get you at the high frequencies.
Hi,
What is the DC voltage and current you need? If you have that, calculate the power required. Then look up how to calculate the rectified voltage from a given secondary AC voltage.
This is all very easy to find on the net and will give you much more understanding than just asking (too) simple questions on the forum. Many people want to help if it is clear that you also do an effort.
jd
Hi,
Will there by any significant advantage in the audio performance if the left and right channels are built as discrete blocks each having their own power supply ?
We will be having 4 blocks:
Best regards,
Bins.
Will there by any significant advantage in the audio performance if the left and right channels are built as discrete blocks each having their own power supply ?
We will be having 4 blocks:
- Left Phono Stage.
- Left Power Supply.
- Right Phono Stage and
- Right Power Supply.
Best regards,
Bins.
Scott, years ago I had a Statement Platinum. That one too was specified at 2 mH, but when I ran it into a 20 Ohms virtual ground input it sounded tonally OK.
I then measured the coil inductance and found ... 60 uH.
LM833 sounds pretty bad for a modern op amp. If you need low noise and FET input you may look at the LF353 but it will be noisy complared to the 833. Maybe an AD712 or if you can take a BJT input try the LT1028.
This is very seldom used even at the highest quality level. For a beginners design which may be based around an LM833 and powered from 7*15 regs it is completely inappropriate.
Even Better!!
Build your preamp with a socket so you may try any dual op-amp you like. A socket will not hurt the sound at all. Here is a good socket:
Digi-Key - ED3308-ND (Manufacturer - 110-93-308-41-001000)
Good sounding op amps:
NJM2068 LF353 LT1028
Bad sounding op amps:
NE5532 ??4558 LM833
Build your preamp with a socket so you may try any dual op-amp you like. A socket will not hurt the sound at all. Here is a good socket:
Digi-Key - ED3308-ND (Manufacturer - 110-93-308-41-001000)
Good sounding op amps:
NJM2068 LF353 LT1028
Bad sounding op amps:
NE5532 ??4558 LM833
That is about the best descriotion of that piece of crap opamp I have ever heard - BRAVO!
Regards, Allen
Pretty please with sugar on top!
Please use a socket (link in earlier post) for the op-amp so you may try different op-amps. Op-amps are cheap to buy and if you make it so they just plug in you can easily discover which one sounds good. The LME49710 is another one of those "optimized" to look really good on paper without concern for the actual sonic performance. The LM833 is exactly the same type of "optimized for audio" opamp. We have already discussed that waste silicone.
Why is the output of the top opamp connected to ground through a 1µF capacitor? That will make the amp misbehave. Can you explain or maybe I missed something.- thanks
Please use a socket (link in earlier post) for the op-amp so you may try different op-amps. Op-amps are cheap to buy and if you make it so they just plug in you can easily discover which one sounds good. The LME49710 is another one of those "optimized" to look really good on paper without concern for the actual sonic performance. The LM833 is exactly the same type of "optimized for audio" opamp. We have already discussed that waste silicone.
Why is the output of the top opamp connected to ground through a 1µF capacitor? That will make the amp misbehave. Can you explain or maybe I missed something.- thanks
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in the National Semi app note the upper op amps are acting as sub regulators for the ps, I would expect the caps on the op amp outputs to need some esr to maintain stability
I do have a philosophical problem with the flat gain block and passive eq topology:
LM4562=dual LME49710, the same app circuit appears in both part's literature
active riaa feedback keeps the feedback factor more nearly constant and keeps slew rate and overload demands much lower
I do have a philosophical problem with the flat gain block and passive eq topology:
LM4562=dual LME49710, the same app circuit appears in both part's literature
active riaa feedback keeps the feedback factor more nearly constant and keeps slew rate and overload demands much lower
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Hi,
The top opamp's are not a part of the audio section. They are part of the power supply.
Best regards,
Bins.
The top opamp's are not a part of the audio section. They are part of the power supply.
Best regards,
Bins.
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