Idea From ROG Splitter-Blend (Would This Work?)

[Paul Marossy]

I had a thought based on a modification to that ROG Splitter-Blend circuit. My idea was to take the two sends and instead of sending them to a chain of effects to send them to an XLR jack for a "balanced" output to an XLR jack. The rest of the circuit would be omitted.

I have really no need for this, but just had the thought and was wondering if there would be more that needed to be done if one was to try doing that. I have a feeling impedance matching would come into play, and audio transformers would be invloved....

[tommy.genes]

The front end of the Splitter-Blend just makes two identical copies of the input signal. To be balanced, one of the copies must be inverted (180^o out of phase).

Check out these Balanced Line Driver projects from Elliot Sound. Neither one uses a transformer.

Project 51 - Easier to understand
Project 87 - Works better, but harder to understand.

To understand balanced circuits that do use transformers, here is the often-referenced Jensen Transformers app note on the subject.

-- T. G. --

[MikeH]

I thought the splitter blend had a switch to invert the phase?

[tommy.genes]

I thought the splitter blend had a switch to invert the phase?

That happens on the return, not on the send.

-- T. G. --

[Paul Marossy]

The front end of the Splitter-Blend just makes two identical copies of the input signal. To be balanced, one of the copies must be inverted (180o out of phase).

Duh. That's right. But I suppose you could still reverse the phase on the copy of the original signal, right?

[tommy.genes]

Duh. That's right. But I suppose you could still reverse the phase on the copy of the original signal, right?

Exactly. In the simplest form, just make one of those non-inverting buffers (U1A or U1B) into an inverting opamp of unity gain. Look at Figure 1 of the Project 51 link from my earlier post.

-- T. G. --

[Paul Marossy]

Duh. That's right. But I suppose you could still reverse the phase on the copy of the original signal, right?

Exactly. In the simplest form, just make one of those non-inverting buffers (U1A or U1B) into an inverting opamp of unity gain. Look at Figure 1 of the Project 51 link from my earlier post.

-- T. G. --

OK, cool. Thanks for the pointer. 

[Vitrolin]

another thing you should have in mind is that a line level is usually around 1volt, and mic level is some where around 1-2 milivolt, so if you send a 1volt signal into a mic input you'll overdrive it and it will be nasty, some bass amps (behringer) has a "Balanced XLR DI for direct connection to your mixing console", yeah right! its line level 1 volt into an input designed to handle somewhere around 1 milivolt.

[Paul Marossy]

another thing you should have in mind is that a line level is usually around 1volt, and mic level is some where around 1-2 milivolt, so if you send a 1volt signal into a mic input you'll overdrive it and it will be nasty, some bass amps (behringer) has a "Balanced XLR DI for direct connection to your mixing console", yeah right! its line level 1 volt into an input designed to handle somewhere around 1 milivolt.

Hmm... that's another thing to think about. Well, it was just an idea. Thanks everyone for satifsying my curiousity.