[Alexdad54]

I  have read white papers by Jensen and gone through other sites that describe how to detect the source of ground hum problems and resolve them and I'm now busy trying to work through all the possibilities and hopefully I'll get it solved without any additional actions. that being said, as a last resort, if I need to get a transformer, does anyone have any recommendations between the Jensen Transformer CI-2RR or the DCI ALH1?

The DCI folks claim their item, which is about 1/3 of the price of the Jensen is more effective but it seems to work on a different principle and I'm not sure if it would be as sonically transparent. Here are the links for both:

http://www.dcispec.com/index.html

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

Any help/advice is much appreciated!

[avahifi]

Hum with what piece of equipment?

What cables do you use?  Are they shielded?  Full braid shielded cables reject external noise best.

Any connections to system from cable TV antenna?

Three contact AC power plugs on some equipment, not on others?

Any high intensity lights, dimmer controls, aquarium pumps, water bed heaters on same circuits or nearby?  Or other devices that put nasty wave forms on your AC power lines or broadcast them?

Please elaborate.

Regards,

Frank Van Alstine

[Alexdad54]

Thank you very much Frank.
Here are some answers:
Hum with what piece of equipment? - I haven't yet determined which piece, busy doing that right now. It's coming from my speakers.


What cables do you use?  Are they shielded?  Full braid shielded cables reject external noise best. - All Grover Huffman SX IC's, pangea and VH AUdio flavor 4 pc's

Any connections to system from cable TV antenna? - Yes, the CATV STB comes into the pre via a Mapletree LR-1 switch but I have a Jensen VRD-1FF on the cable, didn't seem to do anything....


Three contact AC power plugs on some equipment, not on others? - Most of the principal components (pre, amp, cd player, DVD player DAC) are three-prong (plugged into a Majik Buss) but there are some smaller psu's powering other smaller components (a media player, an Audio-GD USB to SPDIF converter, two HDD's etc.) plugged into a multi-outlet box that is then plugged into the wall away from the amp and preamp outlet.

There are dimmer controls in the room but I always keep them off. Nothing else like that close by....

I'm not sure if they're all on the same circuit (it looks like it from the fuse box) and I was wondering if it would be worth the $100 to bring in an electrician to take a look at everything? I'm a renter (long-term) but am ready to make the investment.

Kind of a rat's nest but I am busy re-aligning the components and am going to try and re-arrange the cables so that at least the pc's and ic's don't cross.

[avahifi]

Start with the basic power amplifier and speakers, nothing connected to the amplifier inputs.  Turn this combination on, does it hum?  If so, it is an amplifier issue, or possibly heavy RFI pickup by your speaker wires.  If no hum, then:

Turn amp off, connect preamp to the power amp and then turn power amp and preamp on, and see if it now hums.  Work you way back through the system, source by source, until the problem re-occurs.  With a little logic and detective work, you will find the problem.

Call me for more help, 651-330-9871,

Regards,

Frank Van Alstine

[Alexdad54]

Thank you Frank I'll do that and will get back to you. I really appreciate this.
cheers,
Dave

[Alexdad54]

Start with the basic power amplifier and speakers, nothing connected to the amplifier inputs.  Turn this combination on, does it hum? No Hum with just the amp on.

If no hum, then: Turn amp off, connect preamp to the power amp and then turn power amp and preamp on, and see if it now hums.  It now hums very softly but with no change in volume when I turn the gain up or down. When I turn the volume up fairly high, apart from the still low humming, all I hear is a slight hissing (from the tubes I think?) . This is with no other components connected and all the dimmer lights are off. I tapped teh tubes and they made no sound through the speakers and they are well-seated. The pre and the amp are on the same wall outlet and both have 3-prong plugs.
The Mapletree Audio Ultra 4A SE tube preamp has an output impedance of less than 500 ohms and the Butler 2250 amp has an input impedance of 47k Ohms, could this be a problem?

Call me for more help, 651-330-9871, Regards, Frank Van Alstine  - Will do, after the holidays, thanks Frank

[Alexdad54]

Well, after further research, it seems that my Mapletree Ultra 4A SE has a bit of a reputation for low-level hum, ostensibly due to the design of the separate power supply. I have seen comments on several audio sites to this effect and one possible solution offered by an owner on the Canuck Audiomart forums, "if you drop the gains on the two 'levels' just a HAIR from maximum..then use the standard volume for level after that, some of the hum, or all of it will go away." The poster goes on to say,"The MFA Magus preamps had the same volume arrangement (Gots one of those too),and so does the MFA Venusian (Three chassis Tube preamp-the predecessor of the Luminescence-gots one of them too), and All have the same minor hum issue due to this design consideration. "
I'll try his solution tomorrow but if that doesn't work then I'm out of options other than trying out a Jensen CI-2RR but I don't really want to possible alter the sound....