[Bwanagreg]

I am building a mixed use system, 2-channel music and 7.1 home theater. I want to preserve the sonics of my 2 channel rig, while allowing for pass-through of the LR channels of a 7.1 processor to my amps. How about the following configutaion with a passive preamp.

Input 1: a direct connection between input and output. No attenuation - levels would be set by the 7.1 processor.

Inputs 2,3,...: transformer attenuation as in the standard BA configurations.

Has anyone tried something like this? Any better ideas for this functionality? This configuration would allow be to put most of the money in a great 2 channel DAC, and get a competent 7.1 processor for movies.

[JoshK]

I'll let John answer this definitively when he gets back from LV, but since this is a passive and their is no active gain the solution is really quite simple actually.  Say you have a couple of inputs, use one of them for the LR from your pre/pro.  Then all you do is turn the volume all the way up on the bent pre, since that is no attenuation at all.  Viola!  HT passthrough with no added tricks or features.

[Bwanagreg]

That is certainly a reasonable solution, but the added benefits of the bypass capability are 1. for the purists out there, the signal path is reduced to a wire and two rca jacks, and 2. you don't have to reset the volume when switching inputs - a minor convenience issue, but think about the damage you could do if you switched over to a live source such as a tuner without remembering to turn the volume down!

I found out BTW that Rogue audio has a bypass option like this for their tube preamps.

[JoshK]

Lots of newer preamps have HT passthrough/bypass.  My Cary had it, the Sonic Frontiers has it, etc, etc.  The issue with number 1) is already solved like I said because it is passive it IS a straight wire.  The 2) issue I can understand more, but basically it would be a switch that would do the same thing without moving the volume control.

[John Chapman]

Hello!

Back from CES and will post about that later. Thanks for the question! It's a common situation and in fact the TAP pre-amp was desinged with that in mind - originally the multichannel version had just 2 inputs - one desinged to come from the processor and one from your music source. I am like you in that the HT processor is a secondary thing and I wanted the best 2 channel sound. The system has been expanded and now offers more inputs. The ways to go have both been mentioned above:

Run the outputs from the processor for the front left/right to the Bent Pre-amp and wire the surround stuff direct to your amps for those channels. Then with the standard wiring circuit you'd just turn the level up to unity gain when using the processor. Alternately we could do a bypass toggle but you pay a small sonic price for this as it adds a contact to the signal path that is not their otherwise.

Problem '2' is not that bad in most cases. Because the pre-amp is unity gain at it's max level normally running the system at this level would not hurt anything - It'd just wake you up quick! A system with a high overall system gain might not want that high a level signal to the amps and if that were the case the HT bypass toggle would be the way to go. Let me know what gear it'll be and we can make that call together.

The TAP system (2 box multichannel capable) can be used but will cost more than the kits or a pre-built kit. The TAP system lets you designate any inputs as bypass and then the level jumps to unity gain when that input is chosen and then back to the prior level when a normal input is selected. Now that the kits will have an optional remote control the only reason to use the TAP is if you might want expand the system later to play with  multichannel SACD or DVD-A - or if you want the 2 box arrangement with the cool looking base unit.  


Hope this helps!

Many THanks!

John Chapman
www.bentaudio.com

[Bwanagreg]

Thanks for the reply. It sounds like you have tremendous flexibility in the TAP system.