BHK 250 Hum

I’m getting a loud hum from both speakers when using a single ended connection between the Directstream and amp. The volume is not affected by varying the volume on the DS.

This does not happen when using a balanced connection. No hum at all. Very quiet background.

Also using the same RCA cables with a Rotel power amp produces no hum.

Any suggestions would be appreciated.

Use a balanced connection :slight_smile:

As an experiment, if you haven’t already tried (and if they aren’t already) plug the DS and BHK into the same outlet, power strip or power conditioner. If they happen to be on the opposite phase of your house wiring that can sometimes cause a hum, and sometimes there’s too much voltage difference between the grounds of two outlets even if they are on the same phase.

Thanks Ted. I tried that. The hum still remains.

Use a balanced connection:)

I need the single ended connection to work to go via my tube preamp (balanced to the preamp, single ended to the BHK).

With this setup I still get the same hum.

The two other “standard” things to try are running a separate wire from the DS case to the BHK case (like you would for a turn table…) and as an experiment try a cheater plug on the DS.

The hum might be coming from an input to the DS - if your running a computer to the DS try plugging it into the same outlet… Or if TOSLink is a possibility that’s the ultimate isolation.


I’ll certainly try those things. Meanwhile, does the fact that I get no hum using the Rotel power amp suggest that the DS or inputs to the DS may not be the problem or is that an over-simplification?

Do you have a ‘ground lift’ switch on your Rotel amp you can try?

Your next step might be to insert this one in the RCA IC loop: Iso trafo

alcarp said I'll certainly try those things. Meanwhile, does the fact that I get no hum using the Rotel power amp suggest that the DS or inputs to the DS may not be the problem or is that an over-simplification?
Groundloops suck. Much of the time no particular device is at fault - they just happen and are difficult to eradicate with our more and more connected world/audio systems.

You could unconnect everything then start at the amp with nothing connected to it, if there’s no sign of hum then connect one input, but have that device have no inputs, see if there’s a problem yet, … When you add something that causes the loop you’ll know a little more than you do now. But that loop could be to anything that’s already in the system…

Frode’s idea is a good one if you can’t fix it in a simpler way, say by plugging into different outlets or turning non polarized plugs over…

The Jensen Transformers web site has a lot on diagnosing hum and fixing it.

The samw thing happened at Fremer’s house and we used a simply cheater plug on BHK’s AC plug and it stopped.

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I had the same issue with my Spectral amps (using RCA - no problem in balanced). The only thing that ended up solving the problem was lifting ground using cheater plugs.

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Ted … I followed your suggestions first having nothing connected to the BHK - no hum.

I then connected the DS with no inputs to the BHK- the hum occurred; doesn’t happen with balanced; doesn’t happen with unbalanced to the Rotel.

You mentioned running a wire from the DAC to the BHK. What will I attach the wire to at either end?

Re: cheater plugs I think their use is illegal in Australia.

Well that’s about the minimum interaction :slight_smile: I only suggested using a cheater plug as an experiment. I agree that it’s not a proper long term solution. And are the DS and BHK on the same outlet, at least as an experiment? If not that might be the simplest answer (as long as having them together on the same outlet doesn’t cause other audible oddities.) The hope is that a wire from chassis to chassis would conduct most of the ground loop current keeping it away from the interconnects. A place on the DS is under one of the bridge screws (or the screws on the plate if you don’t have a bridge.) I don’t know if the BHK has a ground screw terminal or not, so I’m not much help on that end.

Hope Paul or BHK can help with the BHK end.

Tried the BHK and the DS on the same outlet. Hum persists.

I am on it. I’ve emailed Peter directly.

Paul … I haven’t received your email.

Can you PM me? Thanks.

I sent it to your GMail account. I need your serial number.

Hi Paul, I just ran into the same issue discussed in this post. Unfortunately this chat doesn’t mention the remedy to the problem. What was the solution? In case you don’t see the problem described, I notice a hum in both speakers when connecting my DirectStream or any other source component via RCA into the BHK250, but with the balanced connection I do not hear the hum. Both units are plugged into a P15 regenerator. I tried plugging both units into the same wall outlet, I tried removing the ground pin on the AC cords, nothing seems to solve the problem, but I need to use a single ended path because I need to use my tube preamp to amplify the DSD audio signal ( needed to be set to LOW output level due to audible white noise in the high setting). My Mystere CA21 preamp only has RCA outputs. I am using an RCA to XLR adapter on the preamp with the XLR interconnects plugging into the BHK, which results still in a single ended connection, correct?
Anyhow, hope you can help.

It’s a bummer that you’re not able to use the balanced connection. You’re right, using an RCA to XLR adapter still results in a single ended connection. Shoot our service guys an email. They will have some ideas for how to get rid of the noise.

Thank you James. I reached out to Larry Lucero yesterday on that topic and hope to get a reply at some point today. I wonder whether something is wrong with my BHK, since I do not
have that problem with any of
my other amplifiers when connecting via RCA.

OK, Larry may be able to help. I would still shoot our service team an email as well. They tend to be a bit quicker with responding to email and will be able to get you in the right hands.

Simple solution is to lift the ground on the amp with a cheater plug and if the amp is plugged into the P15 your still protected. You can try running a ground wire between the two chassis but only 50 percent chance it works. Same issue would occur if you were trying to use the BHK preamp with a SE amp, Jensen makes a product that will solve the problem but it is a couple of hundred dollars.