K&K Audio / Lundahl Transformers

Welcome! Need support, you got it. Or share youe ideas and experiences.

Return to K&K Audio / Lundahl Transformers


Message Sort: Post Order or Asylum Reverse Threaded

Lundahl LL1527/1540 wiring advice

84.106.173.193

Posted on March 12, 2014 at 13:20:45
rjdekker
Audiophile

Posts: 2
Joined: March 12, 2014



Hi all,

I hope anyone can help me out with the following:

My knowledge of transformers is basic so I obtained some advice a few years ago on which transformers to use and how to wire them.

I obtained two Lundahl LL1527's to connect the balanced 100 Ohm line level stereo outputs of a pro audio interface (RME Multiface II) to a mixing console's XLR mic preamp (over a ~80 ft multicore) in a live situation.

In addition, I got two Lundahl LL1540's to connect the balanced 75 Ohm line stereo outputs of a seperate monitor mixing desk to the balanced 10 kOhm inputs on the same audio interface (IEM monitor signal).

I was also adviced to wire both transformer types according to the attached scheme and was assured that this was fine. Faraday shields (E) are only connected to the shield of the outgoing cable.

Recently I read up a bit on transformer theory and also stumbled upon the Lundahl manuals showing completely different suggestions for wiring that I don't understand, also including some resistors on the load side of the LL1540. I'm now in doubt whether the wiring scheme I was adviced is any good and if the transformer types I am using are up to the task anyway!

Any comments on whether this is a good setup would be more than welcome!

Thanks so much in advance.

Regards,

Rob

 

Hide full thread outline!
    ...
RE: Lundahl LL1527/1540 wiring advice, posted on March 12, 2014 at 13:55:30
KevinC
Manufacturer

Posts: 2984
Location: NC
Joined: April 19, 2001
The transformers you obtained are perfectly well suited to the applications you've described.

First, the LL1540: This should be installed in or very near the piece of equipment that it is feeding. The secondary terminating network in the data sheet ensures maximum CMRR. For your application, with a 10K input impedance, the 22K/1nF network is totally unnecessary. The other two terminating resistors won't be useful unless you are installing this in the piece of equipment that it is feeding.

There is nothing wrong with your schematic for the LL1527. It's a perfectly viable alternative to the schematic in the data sheet.

Kevin Carter
K&K Audio
www.kandkaudio.com

 

RE: Lundahl LL1527/1540 wiring advice, posted on March 12, 2014 at 16:42:24
rjdekker
Audiophile

Posts: 2
Joined: March 12, 2014
Hi Kevin,

Thanks a lot for your fast response and expert explanation.

Good to hear that everything is wired up okay.

Great forum!

Regards,

Rob

 

Page processed in 0.019 seconds.