Need suggestions for an a/b switch

[bcycle]

Hi All,

I want to take both the preamp out and the sub-outputs from my surround sound receiver into the RCA inputs of my subwoofer. I want to switch to the pre-out for straight stereo and use the sub-out when listening to surround sound content. Previously, I used a crappy radio shack A.B switchbox to do this but it died.

Does any one know of a non-crappy solution? Can I use a passive RCA source selector (like a Russound or a Niles) for this? Any specific products to recommend that you may have used?

Thanks!

Greg

 

[TLS Guy]

Hi All,

I want to take both the preamp out and the sub-outputs from my surround sound receiver into the RCA inputs of my subwoofer. I want to switch to the pre-out for straight stereo and use the sub-out when listening to surround sound content. Previously, I used a crappy radio shack A.B switchbox to do this but it died.

Does any one know of a non-crappy solution? Can I use a passive RCA source selector (like a Russound or a Niles) for this? Any specific products to recommend that you may have used?

Thanks!

Greg

I don't have a clear idea of what you want to do here. A diagram would be very helpful.

 

[bcycle]

Diagram Attached

Done!

Forgive the diagram. I don't know schematics. Thanks

 

[TLS Guy]

Done!

Forgive the diagram. I don't know schematics. Thanks

I think you are creating a problem that will make things unhandy.

First of all you don't need to use your receiver straight stereo. You can use two channel and use the crossover in your receiver. This is by far your best solution.

I have very accurate speakers and for two channel listening I can't tell pure direct with my external analog crossovers, compared to stereo using my Marantz pre pros crossover. If you click on my signature, you will see that if this rig won't discern it nothing will.

In order for your plan to work, your sub must have right and left inputs as otherwise when you connect the pre outs to the sub everything will be mono.

One of these will work.

However when going from one setting to the next you will need to activate the subs crossover and then deactivate when going back to the sub out. You will also need to change settings in your speaker set up menu.

I would just use the crossover in your receiver and forget, pure direct. Obviously your speakers need a sub, as otherwise you would not be posting this. If your speakers need a sub for stereo listening, then just use the receiver crossover always. Otherwise you have no high pass filter to your mains in pure direct and a whatever order the low pass filter is on your sub.

When you use your sub LFE out on the receiver, you will have second order high pass and fourth order low pass, as long as you defeat the crossover in the sub, which you should. This latter arrangement is usually optimal for most systems.

You are creating awkward problems, for a problem that in reality does not exist.

 

[bcycle]

Thanks for getting back to me.

There is pretty discernible difference in my setup between the "Pure Direct" mode vs. that surround modes. Even when comparing to "Stereo 2Ch" to "Pure Direct" In my Yamaha RX-V2500 Manual it states the "Pure Direct bypasses the unit's decoders and DSP processors as well as shuts down the video circuitry" etc. And it really does sound a good deal better.

The a/b box (when it worked) was a pretty good solution as a means of allowing the sub to work in Pure Direct as well as in surround modes.

So correct me if I'm wrong but I think the crossover in the receiver is not active in pure direct mode nor is the LFE output. (I must confess, I don't know what LFE is).

My mains roll of around 55hz so in pure direct mode the sub just carries the low end and in surround mode it takes the feed from the Yamaha 'Bass Out" setting to "both" to output surround mode low frequency to the mains and the sub.

So my questions now are:

Will LFE work in this Pure Direct mode or do you have any other suggestions that will allow me to use the sub for surround Pure Direct.

Any other considerations, workaround or configurations that might work? Otherwise, I guess I'm still looking for a good box like the one you kindly suggested.

Thanks

Greg

 

[TLS Guy]

There is pretty discernible difference in my setup between the "Pure Direct" mode vs. that surround modes. Even when comparing to "Stereo 2Ch" to "Pure Direct" In my Yamaha RX-V2500 Manual it states the "Pure Direct bypasses the unit's decoders and DSP processors as well as shuts down the video circuitry" etc. And it really does sound a good deal better.

The a/b box (when it worked) was a pretty good solution as a means of allowing the sub to work in Pure Direct as well as in surround modes.

So correct me if I'm wrong but I think the crossover in the receiver is not active in pure direct mode nor is the LFE output. (I must confess, I don't know what LFE is).

My mains roll of around 55hz so in pure direct mode the sub just carries the low end and in surround mode it takes the feed from the Yamaha 'Bass Out" setting to "both" to output surround mode low frequency to the mains and the sub.

So my questions now are:

Will LFE work in this Pure Direct mode or do you have any other suggestions that will allow me to use the sub for surround Pure Direct.

Any other considerations, workaround or configurations that might work? Otherwise, I guess I'm still looking for a good box like the one you kindly suggested.

Thanks

Greg

I think we need to find out why you hear such a difference.

The most likely reason is that you do not have your bass management optimized. I need to know what your mains,speakers and your sub are.

May be your crossover is set too low crating a null, or may be too high and your sub does not go up that high.

Unless your receiver is junk, which is entirely possible it should be transparent.

Now in my system there is no sub, but the LFE is captured. That is the low frequency effect channels on DVDs and BD discs. However when you activate the receiver crossover if you set the mains to small then the bass below crossover appears at the LFE output. Now some devices let you set the mains and other speakers to large and still output bass from the sub LFE jack.

So if your bass management is optimal and your receiver not junk it should be seamless if you bass management is optimal.

A decent DAC and crossover should be transparent.

In my system I use no sub, but the LFE is captured. The speakers are all the same. However I can replace the LFE output with my DIY designed and built circuits. It changes over at the flick of a switch. I can assure you there is no difference. There are probably good DACs and crossovers in your receiver. So I am betting the difference you hear is entirely due to the change in bass management. That should be solvable without creating a cluster, you know what, you are creating.

In pure direct mode there is no output from the LFE (subwoofer) channel.