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Furman IT1230
Old 27th May 2006
  #1
Here for the gear
 

Furman IT1230

I am considering buying one of these units, however I was asked by a friend whether or not I would have to run any special wiring, or have any special kind of plug to power it up. Being somewhat new to the world of balanced power and power units in general I do not know what I am up against, or what this is going to take.

If any of you have experience with this, or have used this unit and have thoughts please let me know.

Thanks
Old 27th May 2006
  #2
Lives for gear
 
nlc201's Avatar
 

No special power. However, in order to get the full effect, you need to have your studio wired with all grounds CONNECTED at the inputs. There is a good chance that your studio was wired with "source shielding", which would be proper to achieve some decent noise/interference reduction. So, you need to reconnect the grounds on all the inputs that had them disconnected as to source all grounds to the new reference ground created by the center tap in the transformer of the Furman. Does it sound like I really know what I'm talking about? Well, I don't. I just know that this is the way. Connect the grounds.


Equitech has some good explanation of this on their website.

www.equitech.com/



From Equitech's website:

"Two basic techniques of audio wiring and grounding will be discussed -- standard methods used in
facilities with conventional AC power and new methods used in facilities with balanced AC power. There are some grounding techniques that apply to both types of AC systems but there are a few important differences.
Most every system utilizing standard wiring and grounding methods will exhibit significant improvement in the system's background noise level when balanced power is applied. Usually, noise can be attenuated still further when some additional grounding methods are used. Under a globally applied balanced power grid, these grounding methods may be used which were otherwise impossible under normal circumstances without increasing background noise. This is due primarily to a unity potential (zero-crossing AC ground reference) that is equally present in every equipment chassis in the studio. Removing most AC ground-lift adapters and reconnecting the majority of shields that were previously telescoped or lifted at one end are some of the grounding techniques possible in a balanced power based a/v system.

A general rule which applies to audio wiring with balanced power is: ground everything, lift nothing and connect all shields (at both ends.) There are a few exceptions which will be described later in detail. If audio interconnections are unbalanced, balance them. If audio is already balanced keep it balanced.

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Audio Ground References
Standard Methods:

All audio interconnections utilize a ground reference. In unbalanced audio interconnections, there is a direct signal mode between one signal conductor and the audio ground. In a balanced audio circuit, there is a common mode signal between two conductors that are inversely phased to audio ground. In both cases the audio ground is part of an audio signal reference that is commonly connected the equipment chassis, which itself is normally referenced to earth ground.

When connecting the audio ground between two pieces of audio equipment, a grounding path is created. If there is an increased potential in any chassis, reactive current (noise) will be introduced into the signal reference of which the audio ground is also a part. This is often called a "ground loop" -- but this is a misnomer. A "ground loop" is not really a loop but an indication of current flow into signal circuits resulting from objectionable voltage potentials traversing the grounding reference. Many techniques have been developed over the years in an attempt to deal with this problem. Some of these methods include using short audio cables, audio isolation transformers, single-point grounding, linear signal reference grids, star grounding, lifting audio grounds from chassis and lifting or telescoping shields. Another common practice involves the use of AC ground-lift adapters on gear with 3-prong AC power cords -- indeed a very dangerous technique. If any component were to short to chassis ground, touching that chassis could place one's body in the grounding path, a typical scenario for electrocution. (Especially if one were to be holding something that is grounded like for example a balanced mike.)

New Methods Used with Balanced Power:

The "ground loop" phenomenon has not been clearly defined until the advent of balanced AC power. The technology provides a new reference point and a new understanding of grounding.

When chassis and audio grounds are connected to the center tap of a balanced AC isolation transformer, they are referenced to the mean AC voltage differential which is equivalent to the zero crossing point of the AC sine wave. There is no current or voltage on the center tap -- here is a clean single-point ground reference for audio. Virtually all chassis, audio grounds and shields can be referenced back to this single point. The center tap of the transformer is then grounded to earth for safety and to shunt any electromagnetic and radio frequency interference away from shields and chassis.

In almost every case, AC ground lift adapters can be removed from gear with 3-prong AC power cords and the chassis of gear with a 2-prong AC power cords can now be grounded without introducing hum and noise into system as may be the case with unbalanced AC power. Most shields that were telescoped or lifted at one end can now be connected and grounded at both ends because there is no longer any difference in potential between the audio chassis. The audio grounds can be connected to a single point at the AC system. Generally as more gear is grounded and shields are reconnected, the system gets quieter.

Occasionally there will be a piece of equipment that has a "dirty" or noisy chassis because of a substandard power supply, internal grounding problems or for other reasons. In many cases this equipment is semi-professional unbalanced audio gear with a two-prong AC power cord. The best way to deal with this equipment is to leave the two prong cord on it, isolate that chassis from any rack rails or other chassis, balance the audio with a direct box or audio isolation transformer and connect it to the console or other device's balanced connections. Then lift the audio ground/shield of the balanced line at the inputs so you do not contaminate your "clean" audio ground with this "dirty" chassis ground.

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Unbalanced Audio Connections
Standard methods:

In a standard unbalanced interconnection there is a one signal conductor and a shield. The shield is commonly an integral part of the signal reference. (Fig.1) One thing that has been done to alter this standard unbalanced wiring configuration is to use balanced audio cable with two conductors and a shield. (Fig.2) Use the one conductor for the signal and the other for the ground. The shield is sometimes lifted at one end of the cable, usually at the input. Often upgrading from unbalanced cables to balanced cables with a good quality shield will yield positive results.

Another approach has been to insert various types of filters into the cable, including putting capacitors in place of a part of the ground wire, in an attempt to remove unwanted hum and noise from the system. This has worked to varying degrees, depending on the nature of the application. However, filters in the audio chain can alter or colorize the signal and capacitors in the ground path are dangerous and could result in a shock hazard.

New methods used with balanced power:

In most cases when using balanced power, unbalanced audio can be interconnected in a standard way. Using balanced cable with a good quality shield is still a sound practice, just connect the shield at both ends. The only exception is when there is a "dirty" chassis (see section above.)

Balancing unbalanced audio at the source with a direct box or audio isolation transformer and running it balanced will lower the overall system noise floor. An example would be using a direct box at the output of a keyboard to balance the signal and sending it into a balanced preamp at the console. Balanced audio is highly compatible with balanced power -- perhaps more than unbalanced audio. General rule: if it's unbalanced, balance it if possible and keep it that way. Remember balanced power and balanced audio both reject common mode noise better than their unbalanced versions.

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Balanced Audio Connections
Standard methods:

In a standard balanced interconnection there are two signal conductors and a shield. (Fig. 3) The shield is normally referenced to ground at one or both ends. Many times the shield is lifted at one end, usually at the input to eliminate "ground loops" or noise. (Fig. 4) The problem with this approach is that while it may reduce hum, the shields act as radio antennas and pickup radio frequency interference from the environment. This can be a serious problem in an environment that has computers, MIDI gear and other digital systems.

Top engineers, as of late 1996, still have not agreed on which end of the shield to connect on balanced interconnections. Though most will tell you if it must be lifted, do it at the input, that way the shield (which now has an impedance across it like a radio antenna) is connected to the audio ground of the output device where EMI/RFI is less likely to be picked up by the input.

The degree to which a cable is balanced from each conductor to ground, as well as it's overall impedance and capacitance, seem to be critical factors in a cable's overall performance. Some manufacturers have even built balanced cables with filters in them to filter out unwanted noise and to deal with the cable as a component in the audio system.

New methods used with balanced power:

In virtually every case, with balanced power, balanced audio can be interconnected in a standard way with the shield hooked up at both ends. The only exception is when a piece of gear has a "dirty" chassis which requires isolation away from the rest of the grounding system. This can usually be accomplished by lifting the audio ground at the input and isolating the offending chassis from other chassis with insulators. A "dirty" chassis condition is rare in professional audio equipment and it often is the result of a substandard power supply or the audio ground not being connected to the chassis. These problems can often be fixed with some effort. In general, wiring and grounding techniques are far simpler with balanced power and it is easier to identify and deal with any offending piece of equipment."
Old 27th May 2006
  #3
IIRC, the IT1230 is going to have a 30 amp connector (twist lock) which will require not only a special wall outlet, but a dedicated 30 amp run by an electrician.

I'm sure you can find out by contacing Furman...
Old 30th July 2011
  #4
Here for the gear
 

thanks for this post. my furman died...and all was not well. i always had it in the cuicuit . so, once it died all these crazy problems occurred all at once. been chasing my tail. this makes sense of it all.
Old 13th September 2011
  #5
Gear Head
 

Wow...thanks nlc201 for that explanation... but now my brain feels like it is going to explode :face palm:

I have just been thrown into the middle of a large audio/video studio building project (too long to explain here), and and doing my best to turn around a situation where not all the right questions where asked...

So my question is this: When you have audio and video as part of a single system such as an audio/video studio, does the audio and video equipment need to be on a single phase, or can it be spread across multiple phases of the mains power? I understand that a balanced power transformer is by nature single phase, so this would require the use of multiple transformers, correct? Or would having them on separate transformers negate the benefit?

Thanks,
Old 13th September 2011
  #6
Lives for gear
 

Quote:
Originally Posted by Gdub View Post
Wow...thanks nlc201 for that explanation... but now my brain feels like it is going to explode :face palm:

I have just been thrown into the middle of a large audio/video studio building project (too long to explain here), and and doing my best to turn around a situation where not all the right questions where asked...

So my question is this: When you have audio and video as part of a single system such as an audio/video studio, does the audio and video equipment need to be on a single phase, or can it be spread across multiple phases of the mains power? I understand that a balanced power transformer is by nature single phase, so this would require the use of multiple transformers, correct? Or would having them on separate transformers negate the benefit?

Thanks,
You are out of your depth. You need a qualified consultant (not a salesman...) to examine your situation and make appropriate recommendations.
Old 14th September 2011
  #7
Gear Head
 

Quote:
Originally Posted by [email protected] View Post
You are out of your depth. You need a qualified consultant (not a salesman...) to examine your situation and make appropriate recommendations.
Thanks for your input Bill. I have already had a qualified consultant look into our situation. I am asking more for my own edification.
Old 14th September 2011
  #8
Lives for gear
 

Quote:
Originally Posted by Gdub View Post
Thanks for your input Bill. I have already had a qualified consultant look into our situation. I am asking more for my own edification.
Ideally you would have a dedicated isolated panel for A/V, with the correct amperage for your needs and expected future needs. For example, one of the theaters in which I work has two dedicated isolated 400 amp panels on stage, down and up left. There is also a sub-panel at the console area and another in the plenum.

balanced power is not usually a part of the spec. It is a little more practical to implement in studios than in theaters and concert halls.

The problem that I see with balanced power for large systems is that there is no spec (of which I am aware, but I'm not an install guy...) for a balanced power mains plug. If you balanced all the AC feeding your A/V panels, what power connector would you use on the equipment cables? and do you need to create a fusing panel, now that you have introduced a second hot? (my Cello amp had just such an arrangement, and I ran it on 208 balanced power.) What electrical inspector is going to pass this, and what insurance company is going to cover it? I haven't checked into this stuff since about 1990 when, in Allegheny County I was told flat out to forget it that the electrical inspector would not pass the system unless I jumped through more hoops than it was worth to me.

If you can run your rig off of a couple of 30 amp breakers, you can buy a couple of plug in solutions like Equi=Tech, Furman, and others offer. I don't know what the difference is or even why there is a difference, but these products seem to be okay in the world of inspectors and insurance companies.
Old 22nd September 2011
  #9
Gear Head
 

Thanks for your feedback Bill, it si greatly appreciated.

So my understanding based on what you've said, and in talking to our consultant, is that any situation where a balanced power transformer is feeding a wall outlet is going to be an immediate red flag to inspectors and insurance companies?

This sounds like a headache...
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