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Old 17th July 2006, 08:04 PM   #6821
kmj is offline kmj  Sweden
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Hey, guys!
I have a question. I'm in the process of putting together a preamp, the "Grounded grid preamp" to be exact.

On page 85 of his book "Audio reality" Bruce Rozenblit writes
Quote:
There is one precaution when using this preamp with a solid state amplifier that responds down to nearly DC. At about five seconds into warm up, a voltage disturbance vill appear on the output which will vanish in one second.
Quote:
The frequency of this disturbance is about 0.5Hz........... It has the potential to drive the amplifiers output stage full for about one half second resulting in a potentially damaging heavy current flow into your speakers
Could this be a problem with the Krell?
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Old 17th July 2006, 08:24 PM   #6822
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Yes, you need to implement the start up auto-mute circuit he suggests further on in the article. Or always turn on your Krell a few seconds after the GG.
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Old 17th July 2006, 08:27 PM   #6823
kmj is offline kmj  Sweden
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D**n, I was hoping that I could get away without it. Well, I'll have go get it working first, then the muting circuit.
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Old 17th July 2006, 08:34 PM   #6824
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The start up mute can be as simple as a couple of resistors, a mosfet, a cap, a diode,and a relay. You can easily knock one up on a bit of perfboard.
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Old 17th July 2006, 08:52 PM   #6825
Zen Mod is offline Zen Mod  Serbia
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Quote:
Originally posted by kmj
Hey, guys!
I have a question. I'm in the process of putting together a preamp, the "Grounded grid preamp" to be exact.

On page 85 of his book "Audio reality" Bruce Rozenblit writes




Could this be a problem with the Krell?

JUST POWER-UP FIRST YOUR PREAMP,AND AFTER 30 SECS YOUR kRELL;
damn caps lock!!!

then pray that you'll not have any brownout or blackout in mains




muting on output of your preamp is not an option .
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Old 17th July 2006, 09:03 PM   #6826
kmj is offline kmj  Sweden
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Quote:
JUST POWER-UP FIRST YOUR PREAMP,AND AFTER 30 SECS YOUR kRELL;
damn caps lock!!!

then pray that you'll not have any brownout or blackout in mains




muting on output of your preamp is not an option .
And after a week or so I'll forget and there goes my dear herukas

Why not muting?
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Old 17th July 2006, 09:09 PM   #6827
Zen Mod is offline Zen Mod  Serbia
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Quote:
Originally posted by kmj


And after a week or so I'll forget and there goes my dear herukas

Why not muting?
ZM:




Quote:
muting on output of your preamp is not an option
I just forget to wrote - it's a must
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Old 19th July 2006, 06:08 AM   #6828
lgreen is offline lgreen  United States
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Default krell-o-tracker

Hi, just checking in, miss you guys.

I count 19 amps made and in progress on the Krell-O-Tracker (bottom of page). Surely by now there are more?

How about some updates to the wiki and some more pics?

zlast, can you fill in the stats of your amp or post them for someone to fill in if you don't know how?

have enjoyed following up on this thread, keep it up.
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Old 19th July 2006, 12:54 PM   #6829
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Default Re: krell-o-tracker

Quote:
Originally posted by lgreen
Hi, just checking in, miss you guys.

Surely by now there are more?

How about some updates to the wiki and some more pics?
I have started to add my clone (plans) a few times, but halfway I stopped because there are too may things I have not made a decission.

I hope to add some details when I have collected enough parts to start building.
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Old 19th July 2006, 01:12 PM   #6830
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Hey Lgreen,

Good seeing you again.

Alas, my KSA project is still in the heatsink-gathering
stage.

How's your Aleph-X coming along?

Cheers,
Dennis
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