Suggestions for DAC isolation?

Have you tried tightening the bolts on the transformer, and putting weight directly on top of the transformer itself (assuming that's possible)? I had a noisy transformer on a tube amp once and that did the trick. For isolation i like Sistrum, but i don't think that will help a buzzing transrformer (nor would any other type of isolation, IMO).

Herbies, 90 day return policy. All my gear is on herbie's stuff.

Normal? Send it back for a replacement. These type of units should not hum/buzz. If a replacement does not solve the problem best to dump it. The expense of your tweak efforts indicated you can step up to a better unit would not hum/buzz.

DAC's should not hum or buzz. Either the mfr. is BS'ng you or it is a defective design/manufacture.

Neal

You're making me think maybe it should be checked out. Still plenty of warranty time left on it. Thanks!

if you are using a berkeley alpha dac that is normal. below is a quote from a review in which michael ritter explains...

"What Michael told me only solidified my belief that sound quality was the foremost concern of the Berkeley Audio team. He explained that the Alpha DAC has two totally separate power supplies for digital and analog, and two power transformers. The dual bobbin transformers used in the Alpha have very high isolation between the primary and secondary windings that provides maximum immunity from line noise. One side effect of this high isolation is a narrow area of magnetic field that causes the bottom of the DAC to hum a little bit. Berkeley Audio Design could have opted for an absolutely silent solution at the cost of sonic degradation. Listeners will be happy to know the hum is inaudible when listening to music even at the lowest volume the Alpha DAC is capable of producing, 0.1 dB."

I've only heard of one manufacturer who openly stated that one channel of their DAC will hum and that it couldn't be heard once music was played. That was Valab.
Now that they have the power transformer in a separate case, their is no noise at any volume setting with no music playing. Toroids are notorious for their nasty sounds and interference unless properly shielded. Heed all the advice given above until something works.

Very interesting Richard_stacy, thanks.
It is a Berkeley Alpha DAC. Any other users?

I like the sound quality of this DAC, one of the best I've heard, so no plans to get rid of it.

rja...mine will be here end of this week. i am very anxious to get it! what digital cable/power cable do you use with it?

I've been through a lot of digital cables in my day. Right now I'm happily using a Kubala Sosna Emotion 1.5m XLR cable that I bought used here on Audiogon. I'm not sure how critical it is with the Berkeley though.

If transformer in DAC behaves like one in power amp then read from Spectron Audio Web Site:

"Mechanical humming from the mains transformer is caused by a varying DC component on the mains grid's AC voltage. The DC component comes from unbalanced loads on the mains grid, such as hair dryers and is present in most households. The amplifier main transformer's vibrations degrade performance of the power supply and when audible can be annoyance as well. Spectron solved this problem by building appropriate filtering circuit below one watt, which is extremely low."

I had it until Spectron changed design of its amp to include appropriate circuitry. You can buy external devices which filter DC component out: one was sold by PS Audio...do search.

All The Best
Rafael

I'm trying 4 Herbie's Tenderfooters between the DAC and maple platform for starters.