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Old 17th March 2011, 09:15 PM   #701
hesener is offline hesener  Germany
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Hi wayne, thanks for the schematic with the voltage values, that is helpful. In my Pearl II, the output stage appears to have 13mA bias current. no big deal....
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Old 20th March 2011, 03:33 AM   #702
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So I have some of these. Not sure where I got them, but it was around the time I was building a chipamp. If I use these instead of mica and thermal grease on the 7824 (u1) and 7924 (u2), do I still need the thermal grease. Also does anyone know what material these are made of? They feel like ceramic kind of heavy and thick.
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Old 20th March 2011, 04:10 AM   #703
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Looks maybe like beryllium oxide. If so, don't break them
or inhale any dust.

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Old 20th March 2011, 09:48 AM   #704
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Why not plain Aavid Thermalloy AlO2 insulators.
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Old 21st March 2011, 11:55 PM   #705
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It's hard to tell with one out-of-focus picture, but since it's much more common than beryllium oxide, it's more likely aluminum oxide (alumina), which isn't dangerous at all. You should still use a thin coating of heatsink compound, to make them mate well to the semiconductor and heatsink. If they are beryllium, that's even better from a heat-transfer standpoint.
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Old 26th March 2011, 05:36 AM   #706
ra7 is offline ra7  United States
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After struggling for almost 2 months, my PearlII is finally up and running.
Due to the monumental oversight of not installing a jumper at Rx, I was
having trouble setting the dc offset to zero. I had fixed that and I could
set it to zero, but it was not stable. Today, I finally got a chance to put
some solid time investigating what was going on. Removing C7 did the trick.
DC offset in both channels is now stable and < 100mV.

It sounds pretty good. Balanced and sweet. It is almost as if its not there....
a quality I find remarkable in any component.

I'm looking to upgrade my turntable, any recommendations? Something in
the range of a Debut III or RP1 would work nicely... or if you guys have
any other experiences. I have a 2M Red and possibly DL103 on the way.

Edit: Thanks nar, hesener and wayne for the help. Appreciate it!

Last edited by ra7; 26th March 2011 at 05:42 AM.
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Old 26th March 2011, 05:17 PM   #707
h-wan is offline h-wan  Austria
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Default coupling capacitor

A question to the coupling capacitor (C13, 22uF):
10uF also will fit?

Many thanks for the information.
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Old 30th March 2011, 08:51 PM   #708
hesener is offline hesener  Germany
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Hi ra7,
glad you are up and running! sometimes it's those simple things.....
as for turntable upgrades, I guess you have a vast choice that will also depend on your budget. myself I am running a LP12 (rather old), with the Ittok2 arm, and a "talisman" pickup from clearaudio. works fine!

have fun
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Old 30th March 2011, 08:53 PM   #709
hesener is offline hesener  Germany
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hi h-wan,
in my Pearl2 I am using a 1.5uF foil output cap with good results. It depends on the input impedance of your line stage (100k in my case so no problem with phase shift or roll-off at the bass)
hope that helps
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Old 30th March 2011, 09:40 PM   #710
ra7 is offline ra7  United States
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hey hesener,

I got a great deal on a Technics SL1300 MKII. It has the well documented problem of a malfunctioning cueing mechanism, but what a turntable!! It is about 30 lbs, very heavy. The built in strobe shows the speed to be dead steady. It feels very solid. I was able to hook up the Ortofon 2M Red I had waiting around for a few months.

The sound is just breathless! The power and dynamics are phenomenal. Trumphets sound like they've been unleashed! You just want to keep turning it up. This is going to satisfy me for a few years and the focus can now be securing more records.

The PearlII is just invisible. It gives you whatever is in front of it. It doesn't lack any qualities, nor does anything jump out and try to impress you. Simply brilliant. Dead quiet too.
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