ABY w/ phase reversal and ground lift

[hobbyseason]

I just came across this and thought it could be extremely handy as a vero layout :)
www.geofex.com/FX_images/TransformerSplitter.pdf

[Ubertech_s]

Can anybody draw this one up??

With a ground lift, phase reversal and isolated transformer outputs it would be excellent at running 2 amps and resolving the inherent problems

Thanks

UT

[Ubertech_s]

[Mulekicker]

[Ooooh, I hope someone draws this up. Need exactly this.

[Neil mcNasty]

Here's a layout for the Hum-Free(er) Splitter.
Been looking over it several times and I'm pretty sure that it is correct/matches the schematic.
But let me know if you spot any mistakes...

I have added some power filtering that is not on the schematic in case you wonder why there are two extra 100uf and 100nf caps compared to the schematic.

This Splitter design does not have any Phase Reversal and Ground Lift functions though...

BUT! A Ground Lift can be added by inserting a SPST (on/off) or SPDT (on/on) switch between the 1nf cap and the transformer. Meaning: add a switch that breaks the connection between the cap and the transformer (one switch for each of the transformers).

Adding Phase Reversal function is something that I expect would require a bit more circuitry (according to my limited knowledge on the subject)

[Ubertech_s]

That is great - I will try it out

Im not sure I understand where the earth lift switch connects but i'm sure I will figure it out

Shame there is no phase correction - it would have made a great solution, like the Radial Big Shot

If anyone can seek out a schematic for a Radial Big Shot ABY let us have it


Thanks

UT

[Ubertech_s]

this is a phase reversal circuit that could be embeded, uses a TL072


from here:

http://sound.whsites.net/project107.htm

According to the signal flow for the big shot it will come after the isolating transformer on channel B, but their design has the earth lift and ø rev on B only, which makes sense (diagram below)

[Ubertech_s]

[Neil mcNasty]

I'll have a look at it and see what I can do...

I see that the Big Shot has a different way of doing the ground lift, then the method that I've been using previously. Gotta try that one. It might be more useful than the one that I've used before (which is totally useless IMO)

Regarding Phase reversal:
The only scenario where I ever have needed a phase reversal switch, is when I have been running two separate pedal chains in parallel going into each their amp.
Then there is a possibility that you come across this problem and would need to correct it.
But when running a single pedal chain into an ABY box, I have never had the need for this, since both amps are receiving exactly the same signal.

There might be amps out there that reverse the phase in their signal path, but that is something I never have come across when running two amps at the same time.
Only when there is a pedal that reverses the phase that is connected to just one of the amps while having both amps active.

Anyway: I'll tro to update the layout with the Ground Lift and Phase Reversal that is featured in the Big Shot diagram, since it is simpler than the other one, that seem to be intended for stereo line signals and not guitar use.

[Neil mcNasty]

Here's a modified version with the Ground Lift and Phase Reversal functions from the Big Shot ABY
Hopefully it works as expected on this circuit...

[hobbyseason]

thanks neil!

i forgot all about this thread, in the meantime i finished building my first amp. reaallly need a good splitter now!

has anyone built this per chance ?

[Ubertech_s]

Hi Guys

Brilliant Neil - I guess seeing as I asked for it, I should rely try it out and verify it

Does anyone know a (UK) supplier of the transformers?

A link would be useful as I cant make head nor tail of the Farnel site - answered my own question

https://www.mouser.co.uk/ProductDetail/Xicon/42TM018-RC/?qs=plB1iWz%252bJMzT%2FlIWSnGXLA%3D%3D

Thanks UT

[Hozy31]

Not that cheap but trustworthy https://www.ebay.co.uk/itm/Audio-Matching-Transformer-Centre-Tapped-on-Both-Sides-Various-Types/111253602759?hash=item19e73b41c7:m:m0Oj90Dxex6UNEbLgn9HcEw

[hobbyseason]

I'm still waiting for my transformers in the post :(

Anyone had any luck with this layout yet?

I've got a a radial big shot on loan at the moment, the phase reversal switch is so handy as i often pair 2 different amps. one of them is almost always out of phase and sounds so weird, hit the toggle and its warm and fat again.

[zosotone]

Interesting project and nice layout! so needs bipolar converter to +9/-9 power true?

[Drjones1106]

In case anybody cares, you can consider this layout verified, though the ground switch as currently wired doesn't work, and just kills the signal in the b channel. I changed it to sit between the sleeve and the ground side of the secondary and ground. Eg, SPDT, pin one and two to the secondary (where the sleeve is currently connected). Pin 3 to ground. I found that this actually does work to remove hum. the other wiring just cuts the signal. I did not try adding the phase reversal switch, though I might add it in the future. I gutted my moreley ABY and and some how it actually fit. thanks for the layout.

[grayfox13]

Dear Neil, what about the 2.2uF electrolytic cap polarity?
I guess that the lower pin is connected to ground, so maybe it is the negative pole, am i correct?
Thanks for the veroboard, excellent work anyway!

[grayfox13]

I built this one too, and I reported the same problem, as shown here the ground lift doesn't work and without connecting SW1 to SW2 (closing the switch) and giving both same ground, the B channel is not working.

I didn't really understand what you proposed with that mod, can you explain better the wiring and what the solution do?

Without ground lift anyway the board can be considered confirmed, working!