monoblocks: one dedicated line or two?

jnovak, I didn't quite understand that. If the power to one amp is in phase and power to the other amp is opposed in phase how does that affect each amp separately? i.e. how do they cancel out?

Just built a new home using 4 dedicated 20 amp lines. 2 lines ( 1 each) for monos. and 2 other for components. Cost about $300. Works fine Using Thor Audio 30 watt tube monos'
Hope that helps.

i disagree with jnovak. i just installed 4-20 amp dedicated lines in my audio room. all the lines are equal length, 10 guage "home runs", from the top of my panel, and on the same phase. my electrician used top level circut breakers. i am using jena labs cryo'd duplex outlets. i am using one outlet each for digital and analog and one each for my monoblocks.

my opinion is that it is ideal to use 2-20 amp circuts for monoblocks as long as they are on the same phase. 2-20 amp circuts will be like giving your monoblock power supply a little more headroom on peaks....it might help but it will never hurt.

after much reasearch i have learned that the potential noise cancelation of opposite phases is far outweighed by the "ground loop" problems caused by trying to use opposite phases.

the electrician that installed my lines is a kind of "electrican to the stars" here in the seattle area. he has done hundreds of high end theatre and audio rooms and has to fix many problems caused by trying to use opposite phases. i recommend talking to a local electrician with experience in this issue for the practical side. doing the basic things right is most important in good power.

i have heard the "opposite phase" viewpoint promoted but feel that hum or noise caused by grounding problems are much more difficult to deal with than actual noise from your local neighborhood transformer.

of course, YMMV.

If I may offer: Any common line-born noise will emerge from monoblock "A" with "+" polarity and any from monoblock "B" will be "-". The noises (is that a word?) will come out your speakers, "meet in the middle" and cancel each other! Result is lower noise floor which is a good thing. GBA

For most amps one 20/30 amp line is generally ample (keep in mind that a 30 amp outlet requires a different plug and outlet rated for 30 amps to meet code), two dedicated lines on separate breakers will be even better. You will have twice the breaker contact area on the service panel's bus bar, and effectively isolate the electrical demand and ground for each channel. Whether they should be from the same phase or one from each phase is something you will have to experiment with. This can sometimes introduce hum. I have two dedicated 20 amp lines for my amp(s) using 10 ga. Romex, and run a line from each leg/phase by using a 2 pole breaker at the service panel. This set up has worked very well with a pair of Bryston 7B STs, and now with a Classe Omicron. For what it is worth, I find the two phase aproach to sound more dynamic, although a smidge leaner then using a single phase.