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Pearl 2 - design oversight
Pearl 2 - design oversight
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Old 8th September 2019, 09:20 PM   #11
PRR is offline PRR  United States
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> You could clamp the output

Then why waste 95% of a good 24V rail to make only 0.6V peak output?? We could get that much out of a fresh AA cell. And hi-fi system levels often exceed 0.6V.

Turn-on thump is a real problem in some systems. I note that many mass-market chip-amps claim to have reduced it (by slow turn-on).

In this case I would *also* cast an eye at the following switching-stage which would not swallow a 24V pulse. That's big, but not hard to defend against. In "professional" work inputs are routinely defended against "any" voltage that might appear on stage or studio wires, even power-amp outputs. At line-level, another 10k in series is not a big deal, and 100V in 10k is 10mA, which most switch-chips will eat OK.

Last edited by PRR; 8th September 2019 at 09:26 PM.
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Old 9th September 2019, 12:08 AM   #12
jackinnj is offline jackinnj  United States
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Pearl 2 - design oversight
Quote:
Originally Posted by PRR View Post
> You could clamp the output

Then why waste 95% of a good 24V rail to make only 0.6V peak output?? We could get that much out of a fresh AA cell. And hi-fi system levels often exceed 0.6V.
Becuz it's an MC phono preamp, going into a preamplifier.

Read the prospectus carefully before you invest.
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Old 9th September 2019, 12:30 PM   #13
rhthatcher is offline rhthatcher  United States
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Pearl 2 - design oversight
Precisely why I use a power conditioner with a delay function built in. The main reason is one button to turn on the system, and the key feature I wanted was this delay function. Phono and Preamp come on to warm up, then the power amps come on. Opposite for power-down sequence. I got a panamax unit on US AudioMart. Price was right and it had the functionality I was looking for. I'm sure it's one of many such products on the market.
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Old 9th September 2019, 06:30 PM   #14
KatieandDad is offline KatieandDad  United Kingdom
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Quote:
Originally Posted by Dennis Hui View Post
Apparently the OP did turn on the Pearl 2 before the Arcam:

Hmm I thought AC coupling was safe

I'm wondering if the Arcam might actually by in stand-by mode when this happened.

Also some preamps that are 'on' when plugged in so it might be advisable to
add a relay to the Pearl 2 output?
Yes I always do. I always power on the Pearl 2 first.
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Old 9th September 2019, 07:01 PM   #15
KatieandDad is offline KatieandDad  United Kingdom
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The Arcam was fully OFF.
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Old 9th September 2019, 07:04 PM   #16
KatieandDad is offline KatieandDad  United Kingdom
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I don't think that diode clamping is the answer here, I'll be adding a relay clamp.
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Old 10th September 2019, 06:49 PM   #17
KatieandDad is offline KatieandDad  United Kingdom
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I step back a bit here after a bit of research. The CMOS switches in the Arcam run at +/-12V which means that their inputs must be clamped at below 12V.

I'm going to go with 10V diode switching for ease of building an external diode clamp.
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Old 10th September 2019, 11:31 PM   #18
wayne is offline wayne  United States
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Pearl 2 - design oversight
Something like this would work as a turn on time delay. The resistor and cap values can be changed to your liking.
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