# tube preamp with surround sound



## scubadj (Oct 29, 2008)

Recently I have been thinking of integrating a tube preamp into my system. On the list of preamps I have been thinking of using are the Rogue Perseus and the Cary SLP98. Both of these preamps come with a home theater bypass which can be used when the preamp is off. The manufacturer states that the preamp”inverts phase”.To correct for this they say to reverse the connections at the amp OR the speaker. I will be using an Outlaw 990 as the HT processor. Do I need to be concerned with this? I don’t want to have to keep changing the speaker cable back and forth . Or is it much ado about nothing? If I do switch the polarity at the speaker will the Outlaw function properly when used? Thanks for any insights or advice. 


Don


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## Wardsweb (Apr 2, 2010)

Are you putting the pre before or after the Outlaw?


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## jackfish (Dec 27, 2006)

"HT Bypass allows the connection of a surround sound processor or receiver’s right and left outputs to be routed passively through the Cary SLP-98 directly to the main right and left outputs providing convenience and signal purity. When the Cary SLP-98 is turned off the right and left home theater inputs are connected directly to the main right and left outputs via an internal relay."

"The Rogue Perseus HT IN input allows the Processor output to be routed directly to the power amps, effectively bypassing the Perseus, without having to unplug interconnects. The front two main channel outputs from the processor should be connected to the Perseus HT IN input."

Once you have inverted the phase to compensate for the preamp phase inversion there is nothing else you need to do, the Outlaw will work as intended.


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## AudiocRaver (Jun 6, 2012)

scubadj said:


> Do I need to be concerned with this?.....Or is it much ado about nothing?


If I understand correctly, in one mode you will have a phase inversion and in the other mode you will not. As long as your two channels stay in phase with each other - and they will - you will never hear the difference.


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## scubadj (Oct 29, 2008)

I appreciate the responses. Thanks. 

Wardsweb - the tubed pre would be between the Outlaw and the amp. 

Jackfish and Audiocraver – If I understand correctly once I reverse the speaker connections – positive to negative – and correctly connect the interconnects from the left and right outputs of the Outlaw to the preamp and from the preamp to amp everything should work normally.

I thank you all for your advice – I’ve been going around and around with this for awhile. I wanted to integrate tubes for two-channel and my home theater into one system. Plus I wanted to have a tube preamp with HT bypass that functioned when the preamp was off but this “phase inversion” threw me. Thank goodness for forums!

Don


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## AudiocRaver (Jun 6, 2012)

scubadj said:


> ...once I reverse the speaker connections – positive to negative – and correctly connect the interconnects from the left and right outputs of the Outlaw to the preamp and from the preamp to amp everything should work normally...


Maybe I am missing something here...

I see no reason to mess with reversing the speaker cables at all. If you do, then when using your new preamp the phase will be double inverted, or "correct." OK. But when your preamp is off, in bypass mode, that inversion is not taking place - it is an electronic inversion taking place in the preamp's circuitry, so it only happens while that circuitry is active and in the signal chain - so now you have a single inversion. No getting around it, inversion in one mode and no inversion in the other, or vice versa, take your pick.

My point was: Inverted or Not Inverted, you will never hear the difference. One person in a thousand will claim they can hear it. One in a thousand of those might be able to prove that they can. It really does not matter.

And now here I am making much ado about it being much ado about nothing.:bigsmile: _Moving on....._


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