Question about hand-built preamp and Cambridge CXU/Oppo

[Sig.Rossi]

Hello,

I have a hand-built passive preamp. Photo is attached.

It has 4 alternatively switchable inputs, volume controls and two simultaneously active outputs.

I don't understand the circuit.

I would like to connect two Class D amplifiers to the two outputs at the same time for a double signal from two pairs of speakers.

I tried it. It works. But I'm not sure if that's just luck. Can anyone say whether there is a risk of something being damaged with that circuit?

I also connected the stereo output and the surround front output from a Cambridge CXU to the inputs on 1 and 3. This means I can switch between the pure stereo signal and the processed surround signal. Does anyone know if this can be a problem? The CXU appears to have no output routing.

 

[Sig.Rossi]

Photo attached

 

[Sig.Rossi]

Totally forgot. To make it even more complicated, I would like to route the rear surround output from the CXU directly and the second output from the passive preamp into another switcher and from there into a Class D amp.

I wanted to use something like this

AUDIOPHONICS RCA Input Selector 4 to 1 Reversible - Audiophonics

This Audiophonics RCA source selector lets you connect 4 analog sources to an amplifier, preamplifier or active speakers. Its function is to allow permanent connection between the various devices.

www.audiophonics.fr

or that

Source selector RCA 4 to 1 / reversible - Audiophonics

www.audiophonics.fr

And from the speaker outputs of the amp

something like that to be able to switch from to different pairs of speakers

Selecteur audio 1 to 2 reversible for speaker / amplifier Black S - Audiophonics

www.audiophonics.fr

Pretty complicated. So I thought I'd better ask before burning down the house.

Really hope someone can help.

 

[Sig.Rossi]

CXU stereo - preamp 1 - output 1- Topping PA 5 II

CXU Sr Front -preamp 3- output 1- PA 5 II

CXU Sr Back - RCA Switcher 1- 2nd class D amp

CXU stereo -preamp 1- output 2 - RCA Switcher 2- 2nd class D amp

2nd class D amp speaker out- speaker switch- speaker pair one and two

CXU front out- active speaker

Gee, any problems here ?

 

[Bill006]

Just wondering if you're getting any distortion from the CXU when in fixed output mode. I'm running it into a Linn active preamp and 2 power amps, and have to use variable output turned down 50%. It also distorts using the coaxial digital out into a DAC unless I use variable and turn it down.My tech guy thinks the preamp maybe doesn't match. Any suggestions?

 

[Sig.Rossi]

I only use mine in variable mode. That way I did not notice any distortion, even when turning the variable mode to max.

Couldn't you just use the variable mode instead of fixed mode?

Or maybe you could try different setups to check which one causes the problem.

 

[Bill006]

I always thought fixed mode was better for sound, at least that was my experience with my old Sony 20ES CD player, which had 2 separate outputs. What did you mean by different setups? It doesn't distort with other DVD/CD players.

 

[Sig.Rossi]

I bet there are people here who can tell you how to measure all of those aspects. Unfortunately I am not an expert. Maybe someone can chime in here.


If your CXU distorts when turning the variable output over 50% I would check how it behaves when using it directly without the preamp. If it is no option to measure.

 

[Bill006]

My 2 amps are 4 channel each with aktiv card upgrades. This puts the speakers in active mode. Not sure I want to try CXU direct in case it all blows. Maybe look for another amp to test. Thanks.