Hovland pre-amp susceptible to A/C line noise?

I have not yet been able to talk to Hovland about the following problem and they have thus not yet had a chance to try to resolve it, but I just purchased a Hovland preamp over the weekend and am having a big noise problem. The preamp seems incredibly sensitive to A/C line noise and thus far has been unlistenable as a result. I floated the ground with a cheater plug to kill a bad ground loop problem (this worked), but I still have a strong and clearly audible buzz/humm. I tried the preamp on two other outlets, and tried putting all source components on different outlets too (and used cheater plugs on everything), but the buzz/humm remains strong (preamp is basically unlistenable). I have both a halogen lamp and dimmer lights which greatly increase noise level (but these lights have never bothered my other components), but turning them off still leaves me with way too much buzz/humm. The only time noise level is anywhere near acceptable is when everything in apartment is turned off (including all source components!), except for amp (VAC 70/70) and Hovland preamp. I tried a Chang power filter last night, which yielded no improvement whatsoever. Getting ready to try Richard Gray filter (and if that doesn't work, maybe PS Audio filter). I've had many tube and solid-state components in this apartment (including two tube preamps, tubed DAC and tube amp) and never before had any noise problems other than ground loop problem.

Any ideas??

Again, in fairness to Hovland, they have not yet had a chance to address this.

First cheap trick: Audioprism Line Filter's. Plug them into outlets next to the biggest offender's. There could be a mis-match in impedance between components. I have the HP100.
Michael Fremer had the same problem.

This is painful, such a beautiful piece causing heartache.

Can you try to run a temporary home run to your electrical panel with an extension cord, to a clean breaker? You will have to cut off the male end and hard wire it into the panel. This might tell you if you have a lot of trash in your electrical wiring in your apartment. You may be sharing neutrals with dirty power hungry equipment. This might at least narrow down the problem a bit better.

Good luck
Are your interconects sheilded? I had bad buzzing with various components until I replaced unshielded Kimber PBJ's with Analysis Plus shielded ones.
Hi Dearing,

Like Rwwear says MF had the same problem but the current production models should have solved this problem. I believe it was due to a resistor in the volume control.

You should call Hovland. Good Luck!
Not only did Stereophile have humming problems but the Absolute Sound had a low level buzz in there review model.
My advice is to send it back the problem is in your pre-amp. It seems they have a problem and are not doing anything to solve it and they know it.
I have an HP-100, too, and am experiencing the same problem. I spoke to Alex @ Hovland and he claimed to not know what I was talking about. I will forward the URL of this thread to him.
Many thanks to all of those who responded to this thread.

Hovland, to their credit, was immediate in their response and identified the problem. As I understood the explanation, the Hovland is a wide-bandwidth design that has little RFI shielding. Between the Hovland and my VAC amp, I am using a long, unshielded Kimber Select interconnect which itself is known to produce buzz/hum in certain installations due to the lack of shielding, the problem usually arising when the IC is used in long lengths. The combination of the two causes noise to enter through the preamp's output. When I threw in a shielded interconnect, the Hovland was basically fine, but the problem returned as soon as I went back to the unshielded Kimber. Hovland reports that this problem exists in 1 of 150 installations and they have a ready-made "RFI filter kit" that they Fedexed to my dealer the day of my call (impressive). I previously ran a CAT preamp, and never had any noise problem using this Kimber interconnect. I do not yet have the pre-amp back from the dealer, but have my fingers crossed that the RFI filter retrofit will solve the problem. As for Kimber, they were quite helpful as always, and discussed perhaps doing a special shielded version of their TAK tonearm cable as a substitute for the unshielded, all-silver Kimber Select that is currently part of the problem. If the RFI filter kit does not work, I will surely consider the Kimber idea.

A couple of comments about your above comments. I cannot speak for Stereophile, but I understood Michael Fremer to write that the hum he experienced came from the MC phono stage in his Hovland review sample and that it was remedied when Hovland sent him a later-generation unit. I have the line stage only and the problem is present at all times that the mute button is disengaged, regardless of the level of the volume control and regardless of the choice of input. Again, the noise largely, if not totally, disappears when I substitute a shielded interconnect as the output interconnect.

Hovland and Kimber have been great about the problem thus far. Alex Crespi reports that the RFI filter usually solves the problem.

Thanks again for your input.
I would return the pre-amp. It sounds like a major design flaw. I would not accept any band-aids fies. In this price range you should expect dead silence..
I had the hovland for a trial period and found it noisy and that it smoothed over too much of the music making it less dynamic than other preamps..
Dear MikeM:

Thank you for your post, and I know you are trying to help me, but I respectfully disagree.

Hi-fi equipment in the league of Hovland or Kimber Select is state-of-the-art and cannot be expected to operate perfectly in every single environment. My guess is that the decisions to not shield the Kimber Select interconnects and to not equip the Hovland with a standard degree of RFI shielding were made intentionally because, it most installations, the designers found that those two products sound better that way, all while knowing full well that, in certain installations, these design characteristics will not be practical. Some street Ferraris have only four inches of ground clearance, and, the motors in those cars demand high RPM's -- drive one here, in manhole-rich, broken pavement Manhattan, and the undercarriage will occasionally bottom out and the plugs will foul due to the engine being lugged down at low RPM's. If you want "practical", you get a Buick or a Rotel. But if it's real glory that you seek, my experience has been that things will likely get complicated.

In short, I do not think it is a design flaw to make a preamp that should be used with a shielded interconnect, or, to make an unshielded interconnect that should be used with a preamp featuring RFI shielding. As for your own experience with Hovland, I'm sure it is as you report -- again, a product like this is not going to work perfectly in every environment.

The problem is not a big deal for me and something that I almost expect at this level. I'll see how the RFI retrofit works and go from there.

Thanks again
I sent Alex Crespi at Hovland the link to this thread and below is his reply to me that I received yesterday. Alex is always prompt in returning emails and calls. Tell me what you guys think of this.

Dear Ian:
Thanks for the link to the Audiogon forum thread. Hope you saw the most recent long post to the thread.
Anyone that gets noise when the HP-100 level control is set all the way down (to what should be the off position) is getting RF coming in on the output cables (between the preamp and amp). As for other noise/buzz/hum problems reported, each and every one that we are aware of is a different situation. (Fremer's was a sample specific
rare problem; TAS reviewed the unit before we changed (over a year ago) our power trans to power the blue lights off a separate winding (which eliminated the slight electrostatic buzz with the HP-100 lights on). Others do need to be careful about grounding and the other junk that is on
the line. While we do not claim to be the most dead silent preamp (definite compromises are made for musicality), we have many hundreds of units in the field around the world, and believe me, if there was a serious noise
problem endemic to the design, we would not thrive in places such as Japan and Germany where such issues are heavily scrutinized.

Feel free to post this for others to see. We ask that forum posters be careful about making broad claims about potential product issues (we are a modest size firm with real people; rumors can quickly do damage to even the
best reputations). Our phones (209-966-4377) are always open to anyone that wishes to discuss their HP-100 or Sapphire installation. We stand behind our products 100% and are committed to seeing that our customers are
happy with their purchase (judging by how many we sell--a lot--and how few used units turn up on the web, I'd say most folks are quite pleased).


Alex J. Crespi
Vice President, Sales & Marketing