why balanced power last before component?

Some noise does pass between the primary/secondary of a balaced isolation transformer, especially toroid, which just about all the popular units employ. IMO, its more effective to place the other device before the balanced power unit, to act as a pre-filter.

Ptss, you have it right. In my DIY balanced power supply, I put a big EMI/RFI block filter with good differential noise reduction figure ahead of the transformers.

http://i994.photobucket.com/albums/af67/mr_classe/Balanced%20Power/b_08.jpg~original

http://i994.photobucket.com/albums/af67/mr_classe/Balanced%20Power/b_10.jpg~original

Plitron has a balanced isolation transformer, Part #8575-X0-02, that is available for sale to DIYers. Equi=Tech has factory B stock and "blems" available for sale direct from the factory from time to time. Toroid Corporation of Maryland also sells balanced isolation transformers. Factory quoted lead time is 2 weeks, but in my experience was more like 3 business days. The transformers in my unit pictured are from Toroid Corp. Schurter, Corcom and Qualtek make EMI/RFI filters that are suitable as pre-filters ahead of an isolation transformer. PM me at sae_2300@optimum.net if you need more specific details.

Here's the link to the Plitron order page:
http://shop.plitron.com/search_new.asp?Action=Search&SearchTerm=8575-X0-02&Search=Search

Glen

Grounding of the center tap in balanced power systems is to keep voltage stable, and for quick clearing of ground faults in equipment operated on such systems. It is an NEC requirement. The same applies to a household supply. The incoming neutral (power company transformer center tap) is grounded at the service panel for the same purpose, to keep line voltage stable, and for fast clearing of ground faults in branch circuits. Any equipment being operated on balanced power needs to have the same quick clearing of ground fault current. I have used balanced power for more than 10 years, and find the benefits to be significant.