Switching preamps in and out

More from Kevin,

The first sentence is true, and the core of the procedure I've suggested to you. The rest of this poster's theory has some flaws, and I would not rely upon his assumptions or assertions.

On 2/5/2013 11:10 PM, Mike Bauer wrote:
Kevin,

So here is the other counter argument about RCA connectors. I didn't want to bother you so I put the question on Audiogon and seemed to have started an argument. See below.

When the power amp's volume control is reduced to zero, its input connection is shorted to ground. Yes, it's true that the input jack is no longer connected to the preamp's ground once the i/c is disconnected. However, you are overlooking that in any modern amplifier, the power amp is still connected to an electrical ground reference due to the ground wire for the AC power connection. The amp is sitll referenced to ground when the input cable is disconnected. I agree with you that if the gentleman was using a vintage amp from the 1950s that used a simple 2-prong AC power connection, the amp would lose its outside ground reference if the input cable was disconnected and there might possibly be a momentary spike even with the inputs shorted. But not with a VAC or any other modern amp.

Final Word from Kevin,

If you switch it to the variable volume mode and turn the volume controls all the way down, yes.

With the volume controls at minimum, the "direct/level adjust" switch will act like a mute switch.

On 2/6/2013 10:01 AM, Mike Bauer wrote:
OK. Thanks Kevin. So just to be redundant: I can "hot swap" the IC's between the preamps with the Phi 300.1a if I turn the volume all the way down.

--- On Wed, 2/6/13, VAC wrote:

From: VAC
Subject: Re: Phi 300.1
To: "Mike Bauer"
Date: Wednesday, February 6, 2013, 5:28 AM

The version of the Phi 300.1 with a front panel meter have a mute switch at the right of the front panel; this may be used to mute the amplifier.

The Phi 300.1a (no meter) does not have a mute switch, but you can effectively mute the unit by switching the attenuators in with the back panel switch and turning the front panel volume controls all the way down; return to the 'direct' mode when you're ready to listen.


On 2/5/2013 7:51 PM, Mike Bauer wrote:
Kevin,

Hello. I'm very much enjoying my VAC Phi 300.1a and Sig. MKIIa preamp combo. I have some audiophile buddies that want to try out their preamp in my system to compare with the Sig. Can I just power up amp,SACD player and three different preamps and switch IC's between preamps without powering off anything if I turn the level controls on the Phi 300.1a down to "0" and have the mute button on the preamps engaged?

I'm hoping "yes" because powering everything off and on and going back and forth for a couple of hours between the three preamps seems like a lot of wear and tear on tubes and such.

Connections are all single ended.

Thanks,

Mike

Kevin's responsiveness never fails to amaze.

Enjoy!

-- Al

Very nice of Kevin to respond so thoroughly. If only all mfrs were as accomodating.....

Agreed. I thanked him for all of us.