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Stupid preamp question


luddite

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I'm trying to troubleshoot a problem with my McIntosh C 27 preamp.

At startup, with the amplifiers turned on prior to the preamp, the C 27 seems to surge.  The meters on my  MC 2125's will pop up, and then settle back to zero.  

Also, i will occasionally hear some static and popping through my speakers, and a low pitched hum with the preamp on, with nothing playing.  

The preamp and amps are plugged into Monster power conditioners, which are plugged into standard wall outlets.  

I've never had the piece serviced, and have a feeling it is time to do so.  Would these problems be typical of a 30 year old preamp showing its age?  

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I always turned on my Mac amp before my C46 preamp. Never had an issue or pop. Usually I'd just leave my amp on most of the time, sounded better when I did that. Both pieces were transistors not tubes though. Looks like one or both pieces will need looking at. Try disconnecting the monster cable power, to be sure that's not part of it.

Sent from my N9131 using Tapatalk

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  • 3 weeks later...

Disconnect everything wired to preamp,including the ground from the record player if you use one.  This also includes the power strips. Then plug it into a wall socket that is different from the ones you have been using  and turn the preamp on and see if it surges. If no surge then the problem is elsewhere.  The preamp does not have to be connected to anything to safely turn it on.

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On 11/4/2018 at 11:41 PM, richieb said:

 

=== general rule of thumb is preamp on, then power amp. Power amp off, then preamp off — 

A couple technical reason for this... 1) A power amp has no break or throttle... when its on its ready to amplify to its full ability any signal presented to it..preamps can and do often makes strange electrical noises as they come up. 

  2) all electronic devices with capacitors are unstable when first turned on. The capacitors leak DC voltage while the B+ is unstable for the first few seconds after turn on. This will send a small amount of unstable dc voltage to the amplifier which not catastrophic but I'd advice against it since it's easily avoided. The above is true of SS or tube gear. 

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Thanks to all for the advice and insight into what I thought was a simple question concerning what happens when I power my equipment up.  

It never ceases to amaze me the collective knowledge of the Group.  

I haven't had a chance to fully troubleshoot the preamp, but hope to do do between the holidays.  

And, I will adhere to the mantra:  pre amp on, power amp on, power amp off, pre amp off.  

 

 

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