What I just had done (still not hooked up to the outlets) is to have a separate 100 amp subpanel away from my main panel for the house and run four separate lines from it, 2 20 amp lines for my amps/active speaker crossovers and two separate 20 amp lines for my front-end components, one of which source component lines has an isolation transformer between the box and the outlets that I will use exclusively for my digital components. I originally wanted to put the isolation transformer between the main box and the subpanel to isolate it from the rest of the house's electrical system, but the electrician said it would not pass code because the transformer wasn't rated for 100 amps. So I figured that the next best thing would be to try to isolate the digital components from the rest of the system to keep the digital garbage from getting back into the rest of the system. Not sure if this is the absolute best way to do it, and ultimately might still want to isolate the subpanel, but this is the way that logically made sense to me. I'm interested in seeing other responses to this thread. |
Since I have a Hubbell 8300igi duplex connector that terminates my dedicated 20amp circuit, could I plug a seperate isolation transformer into each of the plugs? Could this be a configuration to seperate my analog devices from my digital off of one dedicated circuit? |
Vman: You can do exactly as you stated and achieve good results. The key here is how good the isolation transformers actually isolate their output from the line and whether or not the transformers & dedicated line are up to passing enough current without signal degradation.
For best results, isolation transformers should have a noise reduction of -120 dB's, very low capacitance and never be asked to deliver more than 60% ( 75% at max ) of their rated output. This would mean that a 2500 watt ( 2.5 KVA ) transformer should be run below 1500 watts of steady state draw with peaks held to below 1875 watts ( slightly over 15 amps ). These figures incorporates a "fudge factor" in terms of headroom if manufacturers are being a little "liberal" with the power ratings of these transformers. Otherwise, running an isolation transformer at or near rated capacity will actually introduce non-linear distortions into the system, defeating the purpose all-together. Sean
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Sean: Thanks for the excellent information. It is really going to help me as well as others who are contemplating using isolation transformers. From the numbers you've provided, I personally need to run two more dedicated 15amp circuits on top of the existing dedicated 20amp. Then place a 2.5kva iso transformer for the amp circuit and a slightly larger than 1kva iso transformer for my source equipment.
Again, thanks for the excellent information! |
Vman: Run 20 amp circuits all the way around rather than two 15's and the one 20 amp. The cost difference is next to nothing and the difference in potential performance due to lower source impedances with future upgradability ( current draw ) make it worthwhile.
As far as running two more lines, you may only need one additional line but two more transformers. That is, IF the current draw on all of the devices combined for that secondary line are less than 15 amps or so. If you need more current than this, use the two lines as you first suggested.
As i mentioned, there's nothing wrong with running one line for digital and analogue. That is, so long as they are thoroughly isolated from each other. If you're using the transformers that i think that you are, you're good to go. Sean
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Sean: How far apart do I need to keep the isolation transformers from each other? And how far from the equipment (TV, Pre-amp, Amp, etc.)?
I'm probably going to end up running 2 more dedicated 20amp circuits (as you've suggested). I'd like to run each dedicated into an isolation transformer and then on the back side terminate into a Hubbell.
Fortunately my system doesn't draw too much current so my isolation transformers don't have to be very big (taking into consideration your comments earlier about overhead). I have the Sunfire Cinema Grand II amp which is only 225x5, small compared to many that are used. Vman |
I don't know what you have for speakers, listening room or listening levels, but i wouldn't run an amp that size with anything smaller than a 20 amp line and a 2.5 KVA transformer. I would really prefer to see an even larger transformer for this amp, but 2.5 KVA will work for most people with "reasonable" speakers and listening habits.
The reason that i say this is that at low impedances with insensitive speakers, this amp can pull GOBS of current with big peaks or when standing on the throttle. As a side note, this amp benefits quite noticeably from clean power, moreso than some other designs. Adding additional filter capacitance into the power supply also helps with bass impact and to further lower the noise floor. If you're not running this amp in balanced ( XLR ) mode, i would highly suggest checking into it. This amp, along with all other Sunfire products, does not use "standard" XLR pin configurations though, so verify compatability with your Pre/Pro before going that route.
As far as placing the transformers, the greater the distance from each other and the equipment, the better. Given that the field that they generate is directly related to the amount of current being passed, the one to worry about the most would be the transformer feeding the amp. Magnetic fields decay as a square, so moving the transformer twice as far apart results in four times the reduction in magnetic field strength. Having said that, i would keep them FAR away from any type of cabling if possible, as some cables make for excellent "antennas" to feed noise into the system. Sean
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Sean: I posted my system in the "Virtual Systems - Opinions Please" directory of A'gon. My listening room is 15W x 20L x 8H. I usually don't crank the amp too far only because the main speakers are so efficeint (102db sensitivity) that it doesn't take too much to get it loud.
I just bought XLR IC's to go between my amp and my pre-amp. I went with an Acoustc Zen Matrix II (center) Pure Note Epsilon Reference ver4 (mains) and ver3 (rears). All are XLR terminated. I previously was using Monster RCA IC's.
If I cannot do the isolation transformer as my way to provide clean power to my amp, is there another solution you would recommend? I say this because given my space where my equipment is located, I will only be able to have a single isolation transformer for all my equipment both digital and analog. My "bump out" for my equipment is only 8ft wide by 3ft deep. |
Vman: If you would like and since you can't use them right away, send me your cabling and i'll burn in it for a week or so and ship it back to you. This should give you a better idea of what to expect from your system right off the bat. One catch here. You'll have to cover the shipping both ways : )
As to the transformer situation, i don't see a problem with using it to feed the whole system. You will probably end up drawing but a watt or two from each amplifier channel during normal use due to the high sensitivity of your speakers, so current draw is not a problem.
Outside of the iso transformer, what you might want to do is to use some type of device that offers further isolation between components and acts as a "power strip". This will allow you to divide the power coming out of the iso transformer in a somewhat orderly way and keep the components from "polluting" each other's AC supply AFTER the iso. Given that every device that you'll be using has some type of "switching" power supply in it, cleaning it up from the lines coming in and then isolating them from each other should yield further improvements.
I won't go into specifics in terms of brands to recommend, but some type of device that offers multiple feeds with each feed being seperate from the others AND having some type of filtering / surge suppression should do the trick. You can experiment with plugging the amp directly into the feed from the iso or through the "filtered power strip" to see what you think is best. If you don't notice a difference, you might be better off leaving it run through the "strip" for added surge protection.
As far as your installation goes, you'll probably have to angle your center channel speaker down somewhat. You might also want to think about placing some type of wide bandwidth absorption device on the ceiling near the speaker. This will minimize reflections and improve focus / imaging. I'm sure that you'll be very happy once everything is in place. I'm sure that you can't wait : ) Sean
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Sean: Thank you very much for the offer to "burn in" my cables. I'm waiting on one last cable to come in (AZ Matrix XLR IC) and then I'll have all the cables. I would need to check on the cost to ship them to you. If it is not too much, I will ship them to you and cover the return shipping charges. I'm in Northern Virginia, how about you (zip code also)?
Your suggestions about the different ways to improve power delivery to the audio and video devices is appreciated by me and I thank you for your time in offering your technical expertise.
Yes, I'm going to have to "toe" in my main speakers and also angle my center channel down. I've calculated that the apex of the sound from the mains (if they are seperated 10ft) is 13ft. I'll have to use a little geometry to figure out what the angles will be for the mains and the center.
I know that one of the first things I'm going to have to do after set-up is the installation of absorbtive and deflective panels. Wow, this is a fun experience!
Looks like I'll be painting the Man Cave this weekend and then all that's left is the carpet (which I'm not doing thank goodness)! Still shooting for the end of March but will probably be 1st or 2nd week of April. |
