Looking for an in-line "no hum" box for a second amp

[Dr Tony Balls]

Hi all....

I'm looking to connect two amps at once and avoid the traditional hum associated with ground loops. I've built the geofex hum-free ABY before and it works great as a switcher but I really dont need to have all of the switching. I have a main amp, and then I'd like to connect a second which will always be on, no switching needed. I'm thinking that one could build a stripped down version of the hum-free ABY which would sit in line between the signal cable to the second amp, and the amp itself. Does that make sense?

Has anyone heard of such a thing or know of a schematic for one? Alternatively, looking at geofex schematic, what could one eliminate to do the inline version?

http://www.geofex.com/FX_images/humfree2.gif

[phatt]

In that case it maybe as simple as cutting the ground on the cable that goes to the 2nd Amp.
As long as both amps are grounded then it should work.
There will be some situations where it may not work,,, suck it and see

Building the powered splitter box is the better option.

Phil.

[drbob1]

The best solution is usually to have one of the outputs transformer isolated. That said, the Ebtech hum eliminator (inline version) is pretty cheap, hard to imagine being able to build one for less... That said, at guitar frequencies is any 1:1 transformer workable?

[roseblood11]

No, most transformers will kill some highs.
I decided to buy a used Lehle P-Split some years ago and it works great.
Not cheap, but worth the money. When one of the switches didn't work perfectly, I asked Burkhard Lehle what type of switch that was and where I could get them. He send me two pieces for free.

[Seiche]

No, most transformers will kill some highs.
I decided to buy a used Lehle P-Split some years ago and it works great.
Not cheap, but worth the money. When one of the switches didn't work perfectly, I asked Burkhard Lehle what type of switch that was and where I could get them. He send me two pieces for free.

I've been looking for alternatives to the Lehle stuff, as it is rather pricey. Is it just that his transformers are sooo good, or is there another reason why they work so well?

[Dr Tony Balls]

FYI here's a gut of the Lehle P-Split. It doesnt help much because its just a transformer, but thought i'd share.



Makes me wonder what a passive iso would sound like using one of the transformers from the geofex hum-free ABY (mouser p/n 42TM018)

[ilcaccillo]

Looks like an OEP transformer, but with Lehle silkscreened into the MU Metal shield.

[tictac]

I'm working on a stripped down version of the humfree and I'd share the picture but there doesnt seem to be an image upload option in this post....

TT

[ilcaccillo]

I'm working on a stripped down version of the humfree and I'd share the picture but there doesnt seem to be an image upload option in this post....

TT

Use photobucket.com to upload the pictures there.

Then you just copy the photo Link from photobucket and in the message reply windows here, you have an option on top that say "Img" click there and paste the photo link.

Its easy and simple