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

Anything non-technical you want to talk about, talk it over and have beer ...

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

Postby Dr Tony Balls » 29 Oct 2011, 21:43

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
User avatar
Dr Tony Balls
Diode Debunker
 
Posts: 807
Joined: 07 May 2009, 15:29
Location: Brooklyn, NY
Has thanked: 2 times
Have thanks: 153 times

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

Postby phatt » 30 Oct 2011, 06:56

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. :wink:

Phil.
phatt
Diode Debunker
 
Posts: 908
Joined: 04 Aug 2010, 06:17
Location: Bairnsdale ,Victoria, Australia
Has thanked: 0 time
Have thanks: 226 times

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

Postby drbob1 » 30 Oct 2011, 19:18

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?
drbob1
Cap Cooler
 
Posts: 458
Joined: 21 Dec 2010, 21:30
Has thanked: 8 times
Have thanks: 38 times

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

Postby roseblood11 » 30 Oct 2011, 21:49

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.
roseblood11
Opamp Operator
 
Posts: 1644
Joined: 23 Aug 2008, 15:21
Has thanked: 293 times
Have thanks: 291 times

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

Postby Seiche » 31 Oct 2011, 21:15

roseblood11 wrote: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?
User avatar
Seiche
Tube Twister
 
Posts: 2427
Joined: 01 Nov 2010, 01:16
Location: Germany
Has thanked: 217 times
Have thanks: 143 times

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

Postby Dr Tony Balls » 06 Dec 2011, 16:29

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

Image

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)
User avatar
Dr Tony Balls
Diode Debunker
 
Posts: 807
Joined: 07 May 2009, 15:29
Location: Brooklyn, NY
Has thanked: 2 times
Have thanks: 153 times

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

Postby ilcaccillo » 03 Jun 2016, 01:16

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

Image

Image
ilcaccillo
Breadboard Brother
 
Posts: 80
Joined: 11 Sep 2013, 01:02
Has thanked: 4 times
Have thanks: 11 times

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

Postby tictac » 04 Jun 2016, 18:11

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.... :scratch:

TT
tictac
Breadboard Brother
 
Posts: 147
Joined: 27 Nov 2008, 08:30
Has thanked: 0 time
Have thanks: 9 times

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

Postby ilcaccillo » 23 Jun 2016, 21:33

tictac wrote: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.... :scratch:

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
ilcaccillo
Breadboard Brother
 
Posts: 80
Joined: 11 Sep 2013, 01:02
Has thanked: 4 times
Have thanks: 11 times


Return to Freestomp Café!

Who is online

Users browsing this forum: No registered users and 7 guests