Recent News:

Premier 17LS buzzing

Got a problem? See if other members can help you out. Registered users can download schematics, manuals and pictures.
Post Reply
swcng2001
Beginner
Beginner
Posts: 2
Joined: Sat Oct 28, 2017 6:36 pm

Premier 17LS buzzing

Post by swcng2001 » Sat Oct 28, 2017 7:16 pm

Hello everyone,

I have owned the 17LS for quite a few years now and have always been satisfied with the sound. I have it connected to a pair of Krell mono blocks and I love the combination.

All this time, I have connected the pre and power amps via interconnects of my own making. The Krell has only balanced inputs so my home made interconnect which is a shielded twisted pair has the signal connected to pin 2 on the balanced connector, return to pin 3 and the shield to pin 1. I had also connected the shield to the return on the unbalanced (RCA) end. Everything was perfect until I decided to experiment with balanced-unbalanced transformers from Lundahl Problem Solver series. To my astonishment I heard a loud buzzing from both channels (one louder than the other). The buzz does not change with volume control. My interconnects are again home made RCA to RCA in standard configuration (with shield connected to return at the preamp end).

I've been experimenting with different combinations of cable connections including grounding both ends of the shield all without success in curing the buzz problem. Interestingly though, I tried connecting the shield at the input to the transformers via a 100ohm resistor to the chassis of the Krell and it cured the buzzing on one channel but did not have any impact on the other channel.

I'm at a loss in how to cure the problem. Any help or suggestions would be very much appreciated.

Thanks.

Stephen

User avatar
admin
Site Admin
Site Admin
Posts: 1131
Joined: Tue Jan 03, 2012 1:50 pm
Location: New Hampshire, USA
Contact:

Re: Premier 17LS buzzing

Post by admin » Sat Oct 28, 2017 8:56 pm

Hi Stephen,
First, welcome to the site. Sorry to hear you are having problems.

I would try to do a little process of elimination. Do you have another amp that takes regular RCA cables? I would see if you still have the problem with a regular RCA cable vs the complicated RCA to a balanced system you have. (As you know), the idea of having balanced cables is primarily to eliminate ground loop issues but an RCA to balanced converter is not the same as a purely balanced connection signal path. If this does not solve the problem I would get one of those cheap RCA ground loop isolator connectors and put in the preamp to amp signal path. If that solves the issue then you are dealing with a ground loop problem.

If that doesn't solve the situation then I think you may need to open up on the 17LS and see what is going on inside. Again, I would start with swapping out the amp first to see if it's a connector conversion issue.
-admin
Home Theater in Member Gallery
Conrad Johnson Owners.com Main Page

Current Conrad Johnson Equipment in System: Evolution 2000, PV-12L, and D/A-2b.

swcng2001
Beginner
Beginner
Posts: 2
Joined: Sat Oct 28, 2017 6:36 pm

Re: Premier 17LS buzzing

Post by swcng2001 » Mon Oct 30, 2017 5:44 am

Hello,

Thanks for the quick response.

Unfortunately, I don't have immediate access to either a pre or power amp. I will try a ground isolator as you suggest.

The problem seems confusing. As I mentioned in my email, I tried grounding the shield to a convenient point on the Krell which happens to be the release lever for the XLR connector. The buzz went away with one channel of the Krell amps, whereas with the other channel, the hum remained. I experimented with the grounding point and found that the buzz also went away when I tied it to another point on the case. This is a head scratch moment!!

I guess I could live with these chassis connection but there is that nagging thought that there is a ground loop problem somewhere which has not gone away but is masked by what I have done.

I'll keep you posted on the ground loop isolator when I obtain one.

Thanks again.

Stephen

User avatar
admin
Site Admin
Site Admin
Posts: 1131
Joined: Tue Jan 03, 2012 1:50 pm
Location: New Hampshire, USA
Contact:

Re: Premier 17LS buzzing

Post by admin » Mon Oct 30, 2017 7:27 am

You can substitute the preamp by using a 3.5mm to RCA connector from you phone. This is rather good method for hunting down ground loop issues as a phone is isolated from the household current so there should be no ground loop issue with a free floating phone providing the input.

As for substituting the amp, do you have a receiver in the house (for a TV setup for example)? You can pull that and use it as an amp while using the 17LS as an input via RCA connection. Again, this would tell you whether it is an amp or amp connection issue.

Let us know how it goes.
-admin
Home Theater in Member Gallery
Conrad Johnson Owners.com Main Page

Current Conrad Johnson Equipment in System: Evolution 2000, PV-12L, and D/A-2b.

Post Reply