XLR / Grounding Pin Question

grimmace19

Good afternoon Gents,

I bought a Krell kav 250a/3 from a guy on craigslist today. It powers up fine, sends a lot of power to my speakers... but, there is a buzz from the tweets. Now, I know a little hiss is normal for a S/N ratio scenario, but this is loud enough to hear from my seating position and it interferes with the audio to some degree.

I've stripped apart the system, and when NOTHING is connected to the amp besides the speaker cables, I get a very low level hiss from the tweets which I'm very used to from my adcom. This is audible from about 3 - 4 inches away with your ear right at it.

Now, when I plug in my rca style interconnects to the back of the amp and keep them REMOVED from my pre-amp, the buzz/hiss is back in full force.

The Krell manual states to ground the XLR connections when using single ended RCA for hookup. I don't have said pins and they don't seem to be readily available online.

Has anyone had similar problems? Did you eliminate the buzz by grounding the XLR? Does anyone think that trying balanced connections instead of single ended RCA would fix the problem?

CoolJazz

I have several similar amps and have experienced noise before inserting the grounding pin when switching over to use unbalanced in. Simply forgot to put it on once and had that moment of "oh no...what's wrong now" and was very relieved to remember the grounding jumper. Insert it...noise gone.

You can buy those shorting jumpers on line, though I don't remember where right off. Or you could temporarily use a short piece of wire, folded over on the ends to get size to hold in place and inserted into the XLR between pins 1 and 3. Or if you have male XLR's around, make up a permanently soldered jumper.

CJ

grimmace19

^ Thanks for the response! What a world of difference it makes searching for "shorting pins" rather than "grounding pins" with google. Not only do I find the answers I'm looking for, but a link to music direct to order them.

I hope this is the answer to my problems, otherwise we're going down another rabbit hole of XLR that I'd prefer to stay away from.

Speedskater

The rabbit hole is not the balanced XLR interconnect system, the rabbit hole is that now some 20 years after the the first paper on correct system wiring some hi-fi manufactures are still doing it wrong.

This is the best way to wire an RCA to XLR interconnect.



If that doesn't work, then we need to talk about building a John Windt 'Hummer' tester.

grimmace19

Got the cardas pins in the mail today from music direct. Shipping cost as much as the pins themselves. Put them into pins 1 and 3 per the krell manual and BOOM, dead silence from the amp.

After hooking my entire system back together and moving some stuff around, I've had the krell going for a while now and HOLY F$%*ing S@#$ it's amazing. I never knew the lsi15s could sound this sweet. I tried an adcom 5802 a while back with my exact same gear in place as I have now and it wasn't in the same world as this is. The detail and punch of this thing compared to my adcom 7500 is insane.

Now, it's even more of a tease to know that my Triton Ones are ready for pickup but I can't fit them in my car. With the wife out of town, it's going to be at least a week until I can pick them up.

D_M

Exactly Grimmace19. LSIs fed with amps that double the watts as ohms dips, can really put a smile on your face. It's even better if those LSIs are supplemented with a sub that can cover the stuff below 150Hz.