John Curl's Blowtorch preamplifier part II

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#93,941
vacuphile said:
I would leave you at the stake for the crows to eat your flesh off your living bones. Why waste firewood?🙂
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Over here we call those a Gibbet!
The MC stage without RIAA is an interesting idea, but has as a downside that short pulses from clicks and pops could (will) easily overload the amplifier stage. Why not have the easiest of all low pass filters get you the required roughly 10dB/decade down slope before or incorporated into the amplification stage, and then do the finer corrections digitally?
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Yes that is said by many, but I don't buy it anymore*. Scott provide in his testing for the LA article that clicks really don't cause any problems, and a phono stage with a slow recovery should you actually exceed the limits is not fit for purpose. 24dB headroom seems to cover all but the most pathological record damage. If you are ripping to then process, the declicking in most tests seems to work better before correction.

* I did used to believe this, but just because people write it down doesn't make it true. Think about all the flat MC headamps that seem to do fine.
 
#93,942
As long as you stay all analog. They (clicks and pops) will wreak havoc not immediately known in ADC/DAC. The broadband distortion products from clipping add a harshness or false high-frequency brightness.

Inter sample overs are common in low sample rate (44.1kHz) commercial releases. Benchmark avoids clipping problems with added head room -- re. DAC 3).

"We believe this added headroom is a groundbreaking improvement."

---Benchmark.


THx-RNMarsh
 
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#93,954
What happens if you try to pass the mistracking transient shown in Fig. 7?
Can you do it, Billshurv?
 

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#93,957
John: Would really help if you scanned the part of the page that stated what the test record was. Given Scott managed to trace the square wave CBS test track pretty well with a Grado I am not sure what your point is? If you can give me a test you want doing once assembled happy to try it.

Richard: There will be no sample overs AFTER digital RIAA. And even if there were a 3.5dB digital attenuation before the DAC would remove it.
 
#93,958
Bill,

Let's talk magnetics for a moment. The big three cartridges are moving magnet, moving coil and variable reluctance (probably the lowest basic output.) For the moment ignoring other techniques such as piezo, strain gauge etc.

The peak voltage for any magnetic cartridge design will not surprisingly vary by design. 🙁

Just between moving coil designs, back when I paid attention there could be more than a 10 dB difference between models and manufacturers. Perhaps as high as 20 dB.

So unless you plan to sample all the cartridges....

Of course for your cartridge in your use, your clearly useless, inadequate and foolish design ( 😉 ) may be adequate or even quite good.

But as you know "All blanket statements are wrong!"

ES
 
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#93,960
billshurv said:
MCs vary about 0.05mV to 5mV. But I only have 0.25 and 0.4. As gain is variable at the front end (more heresy) not worried. I should also note the basic design was done by people much much cleverer than wot I am. I'm just playing with it.
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Confusing normal output with the clipping level! Normal is fine for design center, but the issue was pop and scratch level and that need not be related to normal output!
 
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