Wet / Dry boxing using 2x Signal Buffer / Inverter PCBs

[Ctrl4Smilerz]

Hi all,

I would like to dip my toes in the Wet/Dry amp world. I was thinking of using 2x Signal Buffer / Inverter PCB's but have a few questions:

1) Do I simply wire both boards to the the tip of the input or is there a better way to do it?
2) Is there an easy way to add a ground lift to one of the outputs?
3) Is a SPDT (On/On) the best choice to control the phase?
4) Is there anything else that would improve this project?

 

[giovanni]

1) I think that should work, assuming the buffer has a capacitor in the input stage. I would experiment and see. If that does not work, you can put a buffer before the two buffers. That would solve any loading issues but there should be none because those buffers should have a very high input impedance.
2) I’m not an expert here. I heard that it’s doable but I would just add a transformer after the buffer to be safe.
3) I think that should be fine since the circuit has both in and out of phase signal. You need that only for one of the outputs.
4) besides the transformer, you may want to consider making one of the output foot switchable. I think that may come in handy.

Let me know how that is, I have been wanting to try dual mono forever. I am a fan of TPS and really like their dual mono setup. Btw @JamieJ sent me a board that does exactly what you’re trying to do. I never built it because I’m the worst

 

[Ctrl4Smilerz]

I'm taking another look at this idea:
1) @Robert can you confirm if the Signal Buffer/Inverter has an input buffer? If not could I use the simple JFET buffer or is there a better way to do?
2) It looks like this transformer is what other have used, but I don't under stand how to integrate it into the signal. It has 6 pins, how can I wire it into the signal path with a switch for ground lift?

As always thanks

 

[jwin615]

For ground lift just use an isolated jack and put the sleeve signal on a on/off switch or use 2)3 of an on/on. No need to isolate the signal with a transformer as the next device(amp) should ground the sleeve on the input.

 

[Ctrl4Smilerz]

For ground lift just use an isolated jack and put the sleeve signal on a on/off switch or use 2)3 of an on/on. No need to isolate the signal with a transformer as the next device(amp) should ground the sleeve on the input.

Thanks. I don't think I've used an isolated jack before and when I searched Tayda for isolated jacks nothing came up. What makes them different and do you have a link you could share?

 

[giovanni]

For ground lift just use an isolated jack and put the sleeve signal on a on/off switch or use 2)3 of an on/on. No need to isolate the signal with a transformer as the next device(amp) should ground the sleeve on the input.

I always wonder why people use transformers if a ground lift will do the same job? What are the pros and cons of either solution?

 

[giovanni]

Thanks. I don't think I've used an isolated jack before and when I searched Tayda for isolated jacks nothing came up. What makes them different and do you have a link you could share?

The difference is that in an isolated jack the sleeve is disconnected from the chassis, which is usually grounded, so you can lift the ground easily.

Edit: search for “insulated jack” on Tayda.

 

[jwin615]

I always wonder why people use transformers if a ground lift will do the same job? What are the pros and cons of either solution?

Usually transformers are used to change impedance/level(DI) or to split the signal. Also for balancing the signal for noise(DI) for long cable runs.
The only other reason would be to maybe block DC, thinking 48v phantom.
When it comes to splitting, the transformer is better than a passive split as you can get 2 isolated splits. So, if the load on one side of the split changes, it won't impact the other output.

 

[Ctrl4Smilerz]

Alright, I think I can piece this together, but have one more question; If I'm only going to include one phase reversal should it be on the same or opposite channel as the ground lift?

 

[jwin615]

I would ground lift both channels simultaneously. No point in doing just one as you could still have a ground loop via the other channel.
Phase reversal should probably be both channels as well, but individual switches.
You hear discussions around 1 diode hard clipping fuzzes(ala dizzytone)and one direction(for the diode) sounding better than the other direction. That's because the speaker excursion and the compression and rarefaction of the sound wave produced are completely different.
So, with only one phase invert, you could get the signals in phase with each other, but out of ideal phase.
You also have to take into account things like floor monitors and other sources when it comes to phase.