Help! Possible ground issue???

Wayner · « **Reply #20 on:** 3 Mar 2011, 10:23 am »

Here is a nice power distribution center that may help solve some ground loop issues (especially if you are using multiple outlets (even worse, on separate circuits)), made by Tripp-lite. I have the 6 outlet version and is a nice way to get all the stuff connected to a single ground point.

Here is a shot to a website: http://www.parts-express.com/pe/showdetl.cfm?Partnumber=125-144

It also has surge protection. They also offer other similar devices that may stir interest. We used these at work by the hundreds (if not thousands).

Wayner

pjnad · « **Reply #21 on:** 3 Mar 2011, 01:22 pm »

Well, if and when I still have the issue when I get the pre back from Modwright , this certainly looks affordable...
Are you suggesting that I use this and take the ps audio out of the loop entirely? or can I plug everything into this and then plug this into the ps audio conditioner and that into the wall?
As I mentioned earlier, I do receive some sonic improvement using the ps audio.

pjnad · « **Reply #22 on:** 3 Mar 2011, 01:29 pm »

Ever see or use something like this?

http://www.jensen-transformers.com/ci2rr.html

This site has a ton of info on ground loop issues from Bill Whitlock.

pjnad · « **Reply #23 on:** 3 Mar 2011, 01:35 pm »

Or this?

http://www.jenving.se/?p=humbust

Wayner · « **Reply #24 on:** 3 Mar 2011, 08:12 pm »

Those 2 options are using isolation transformers on your interconnects and would not be my first option. I'd rather see you get a few "cheater" plugs and turn some of them 3 prong plugged components into 2 prong. If one stayed grounded, that would be OK. Then you could at least get the system quiet. The next step would be to remove the cheater plugs, one by one until the offender is discovered. It may be just one component like a CD player or an FM tuner.

I had an FM tuner (Soundcraftsmen) that would make the system hum, even when it was turned off. If I unplugged it from the outlet, the hum stopped. Needless to say, that tuner is gone (replaced by the incredible Sony XDR-F1HD digital tuner.

Your next mission, when your amp comes back is to hook everything up with cheater plugs and confirm the system is quiet. Then one by one, remove the plug and evaluate the system again in each progressive step. This will target the bad boy. If you don't do this, you will never know the cause.

Wayner

pjnad · « **Reply #25 on:** 3 Mar 2011, 08:34 pm »

Wayner:
While I was initially troubleshooting ( with Dan from MW) on the phone, I did actually unplug both of my source components (dac/transport) and the hum was just as loud as before.
So, my guess is that I have already isolated the culprit: the MW pre...
Again, I'm actually hoping that there was something 'wrong" with it and that Dan finds and fixes whatever it is.
If I get it back and am still experiencing the hum, my first plan of attack will be to outfit everything with the cheater plugs and go from there...
question: would that tripplite unit replace my ps audio or could that be used in conjunction, i.e. plugging that into the quintet which would then go to the wall?
Paul

Wayner · « **Reply #26 on:** 3 Mar 2011, 09:07 pm »

The Tripp-lite really just has surge protection and isolated outlets (between each set of duplexes) and that is a nice feature for some components that have interacting power supplies. I would think you could use both of them together, but I think you have to get the unit back first to find out what is up.

I don't have much faith in power conditioning units myself, but that's just me. I'm not really sure what the claim to fame the PS unit has to offer.

Wayner

pjnad · « **Reply #27 on:** 3 Mar 2011, 09:32 pm »

Well,
Initially I had needed the extra outlets and was using a pretty basic power strip (Monster), but I was at an audio shop and he had the ps audio quintet available at a great price, so I figured that I'd give it a try since it also claimed to isolate the components as well as providing surge protection and some cleaning. I must say that I did notice some sonic improvement: definitely music coming from a "darker" quieter background.
So, for now, if I can, I'd prefer to keep it in the loop.
Thanks again for all your communication...I guess at this point I'm just going to have to be patient until the pre gets back.
Paul

Mark Korda · « **Reply #28 on:** 6 Mar 2011, 08:28 pm »

Hi PJnd,I don't know where you live,but in Maine there is a huge problem going on now with CMP(Cental Maine Power)they are our electric utility.They have these new meters installed or are in the process of installing that send radio signals back instead of having manual meter readers.People are complaining all over the place about them,even opting by law to not have them.There are all sorts of complaints from dizziness to insomnia and maybe something you might be encountering.There is a front page article in todays,Sunday March 6,Portland Press Herald(Maine) and I know you can go on line to read it(Google will find it).Maybe your electric utility is doing the same thing?,just a quess......Mark Korda

pjnad · « **Reply #29 on:** 23 Mar 2011, 02:14 am »

Hey Everyone,

I received the pre back from MW this morning, Dan had checked it out and gave it a clean bill of health. So, I hooked it into the system as before...still have the hum. I started troubleshooting: changed over to rca cables-hum, cheater plug on amp=hum, cheater on pre=hum, stock power cord=hum, extension cord to outlet on different circuit=hum, simple power strip instead of ps audio quintet = hum...and this is all with no sources connected to the pre.

So, I tried a simple suggestion that someone had made- I ran a thin wire from the chassis of the amp to the MW, because the cover was off, I touched it to one of the rca inputs = NO HUM!!!
I went out and got some 16 gauge wire and some ends that I crimped on, ran the wire from the Krell chassis to the MW chassis = HUM....disconnected the wire from the MW chassis and connected to an unused rca input = NO HUM!!!

I guess the problem is solved,as inexplicable as it seems. I spoke with Dan at MW and he can't explain it either, except to say that maybe something was loosened or jostled in shipping it back to me, because the chassis and inputs should both be grounded...and he checked the entire unit over while he had it. He suggested a run a multimeter to check, which I will do eventually, but for now, I'm up and running!!!
Thank you to everyone who has chimed in with advice, folks like you are another collateral pleasure of this search for musical enjoyment.
Regards,
Paul

Bill Baker · « **Reply #30 on:** 23 Mar 2011, 03:32 am »

Hello Paul,
Something else I would try is simply running a short wire from one the RCA inputs on the MW direct to the chassis of the MW. What you have is a ground issue and is sometimes common depending on the ground scheme of the amplifier vs preamp. Some amplifiers will ground the input to the chassis while others will ground it to the circuit ground. Different configuration can sometimes cause ground noise issues with certain preamps.

In theory, either the interconnect cable, power cord or both should provide the proper grounding but it doesn't always work out this way.

It's not a fault of either the amp or preamp rather a difference in the grounding scheme than can easily be overcome as you have obviously found out. At least now you can sit back and enjoy the music as what you are doing will not harm any of the components.

pjnad · « **Reply #31 on:** 23 Mar 2011, 04:00 am »

Quote from: Bill Baker on 23 Mar 2011, 03:32 am

Hello Paul,
Something else I would try is simply running a short wire from one the RCA inputs on the MW direct to the chassis of the MW.

Bill,
Would there be any benefit to running the wire as you have referenced instead of the way I have it now , i.e. pre to amp.
Thanks,
Paul

ctviggen · « **Reply #32 on:** 23 Mar 2011, 11:21 am »

It would be simpler, easier, and you can remove components easier. If you're happy with the way it is now, though, then it should be OK.

pjnad · « **Reply #33 on:** 24 Mar 2011, 01:25 am »

Oh, and a big by the way...the personal service, communication, time, and help that I have received from Dan Wright, President of Modwright has been outstanding! This includes communications that we had before I even purchased a previously owned unit...

So far I am very pleased with the performance in my system as well; if anyone out there has a Modwright unit or modification on their shopping list - I would highly recommend Dan as a person and company to do business with!

Berndt · « **Reply #34 on:** 31 May 2011, 02:54 am »

I know this is slightly stale, but, having recently been playing with a Krell Ksa150 and guess what. Humsville.
Owners manual states if single ended inputs are used to use shorting plugs on the balanced inputs. Bridge pin 1&3.
This helps the hum for me. Having spoken to a few Krell familiar dudes they are saying the balanced inputs must be used for quietest performance. Will be trying some se to balanced cables.

Berndt · « **Reply #35 on:** 31 May 2011, 02:57 am »

Krell Ksa150 hum is also a very common malady and sign of impending recap. Super gutsy brawler of an amp. Redefines bass control and slam.
A tad on the sterile and harsh side. Too spoiled by my tooby goodness.

pjnad · « **Reply #36 on:** 31 May 2011, 03:11 am »

Quote from: Berndt on 31 May 2011, 02:57 am

Krell Ksa150 hum is also a very common malady and sign of impending recap. Super gutsy brawler of an amp. Redefines bass control and slam.
A tad on the sterile and harsh side. Too spoiled by my tooby goodness.

Thanks...I have pretty much solved the hum issue in re: hearing it through my speakers, but the Krell itself does hum, which is noticeable when you get close to the amp. This might be where the last vestiges of noise that I do hear through the speakers is emanating from??? I am running the Krell w/ balanced cables and coupled with my tube preamp the system is sounding pretty good.
I would certainly consider using a different amp but currently, finances leave me having to enjoy what I have...
What do you know about recapping, and what would it benefit besides potentially reducing the hum??

Berndt · « **Reply #37 on:** 31 May 2011, 03:18 am »

Recapping is not unreasonable considering these amps are twenty years old. Threads on diyaudio also suggest biasing this amp a little lower also smooths the hard SS top end this amp has a rap for.
I have some queries in to the Krell gurus regarding pricing for recapping. Will post back anything I learn.

pjnad · « **Reply #38 on:** 31 May 2011, 12:11 pm »

Thanks...I'd appreciate any further info!

Berndt · « **Reply #39 on:** 31 May 2011, 04:00 pm »

http://www.stereorepair.net/

This gentleman is an ex Krell employee and regarded as a Krell guru.
Told me 550$ for a total recap.