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Jeff0000
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questions

A couple of questions, if I might ...
1) The difference between balanced and unbalanced output and why one might choose one vs. the other.
2) Difference between Voltage Mode and Current Mode and, again, why one might select one vs. the other.
Thank you,
Jeff

mrlowry
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Re: questions

This will be a bit of a simplification but in a single ended connection (normally utilizing an RCA connector) there is a "signal" (the music) and a "ground" (electrical ground.) In a balanced connection (normally carried on and XLR but sometimes on other connectors for PRO applications) there is the "signal" (again music) the "ground" (electrical ground) then the third leg is "the signal 180 degrees out of phase." That is to say AN EXACT OPPOSITE of the original musical signal.

The practical benefit is that if the entire system is balanced, including inside the components at the end of the chain the "signal" and the "inverse of the signal" can be compared. Anything that they have in common must be noise picked up in the journey of the signal, and is therefore discarded. Making for "blacker" backgrounds and wider, deeper sound stages.*

It is important to note that just because a component has XLRs on the back DOES NOT mean that the circuit is truly balanced. Many time manufacturers will add XLR connects for comparability with other gear OR as marketing hype. A truly balance circuit close to doubles the price of a component because for every wire, cap, resistor, etc there must now be two. Only the chassis and the power supply don't need to be doubled. If it isn't balanced throughout the entire circuit, it's of negligible value. In fact, a pseudo-balanced design adds one EXTRA part in the signal path that wouldn't be in the signal path for the single-ended connections which is usually phase splitter used to "manufacturer" a balanced signal when only a single-ended one exists.

Voltage mode vs. Current mode is a "Krell Thing" and hopefully someone else will come along to give you a good explanation. I looked on their website to see if they had a good FAQ, which unless I overlooked it they do not.

*Not everyone agrees that balanced connections run over shot distances have an audible effect, including some very good manufacturers. Like many things in high-end audio there are some very knowledgeable honest people on both sides of the fence. For the record my system is balanced, but I've many impressive systems that were purely single-ended.

Jan Vigne
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Re: questions
Jeff0000
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Re: questions

MrLowry:

In reading the review of the Halcro dm88 ... this is where the Voltage Mode/Current Mode came up ... apparently this amp has 4 different inputs, of which, voltage mode and current mode are 2 of them ... both balanced and unbalanced.
Which I, obviously, do not understand.

Jan Vigne
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Re: questions

I don't remember the Halcro review but consider the "voltage" and "current" options to be a choice between voicings of this amplifier. Tube based power amplifiers are generally considered to be voltage drive as tubes tend not to produce high current. "Current" drive would then be considered more akin to a solid state amplifier's generic characteristics. You're speaker selection would largely determine which of these two options you might chose.

JoeE SP9
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Re: questions

Some of the Carver amps had the same options. IE: current based or voltage base outputs. Bob used to advertise that the voltage outputs were for panels and ESL's and the current outputs were for moving coil speakers.

Jeff0000
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Re: questions

Thanks Joe. I googled Carver and think I found the article ... seems Bob was saying Voltage for Moving coil and Current for panels and ESL's. Additionally, I got the impression on the imput side that Voltage for SS and Current for tube, not to mention a page or two devoted to those with PhD's in electronics explaining the whole thing. However, I think I'm a little less fuzzy on this now .. thanks! BTW, did see an article when I googled Carver ... apparently there was some sort of "dust up" between Mr. Carver and Sterophile back in the early 1990's .. thought that was a little disturbing.

Jeff

mrlowry
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Re: questions

Jeff-

Yep Bob Carver is a bit of a snake oil salesman sometimes. I'm not saying he's a bad engineer mind you but he does tend to wildly exaggerate at times. It's always best to take him with a grain of salt and to fact check.

Welshsox
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Re: questions

Balanced v Unbalanced is a very logical thing, im not sure what current v voltage means ?

At the end of the day a signal has certain properties that depend upon its source, you can increase the voltage and reduce the current or vice versa but its still the same amount of energy. Its just sounds like a snake oil thing.

commsysman
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Re: questions

On a balanced connection, the signal is carried by two signal wires, neither of which is grounded; the grounded shield is separate. The receiving circuitry senses only the Voltage Difference between the two signal wires, which means than any electrical noise, RF, or hum (which would be picked up by both wires equally and thus NOT induce any voltage DIFFERENCE) is not sensed at all and is effectively non-existent in the receiving circuitry. This allows balanced connections to be run virtually any distance with no signal degradation, even in environments which would be highly degrading to unbalanced connections.

In an unbalanced cable, the "ground" shield has to carry the signal return current, which means it cannot truly be "grounded" at either end; it must be a "floating" ground in order for the return signal current to be induced in it. It also cannot "shield" itself AND carry signal current. The shield function is essentially contradictory to the signal-carrying function, and this makes the entire concept of the unbalanced cable rather stupid. This makes it vulnerable to noise and hum components which corrupt the signal and also to interactions with the circuitry at both ends which can cause ultrasonic oscillations in the cable. It also means that the point labeled as "ground" in the signal circuitry at either end in the equipment can also not be a "true" ground and is subject to noise in some degree (if both ends of the shield or "ground" side of an unbalanced cable were at absolute ground, then there would no way for the signal return current to exist; it could not be induced to flow if both ends were truly at 0 potential).

In essence, the minimum requirement to do the job properly is 3 wires, and an unbalanced cable tries to do it with 2. It doesn't work well at all.

The engineering problems with unbalanced connections are so limiting and such a miserable can of worms technically that I can't understand why "high-end" equipment manufacturers do not simply reject them completely and go 100% balanced. I struggled for years with unbalanced connections and finally realized that they are simply inadequate and inappropriate for a high-performance audio system. Even when you keep them shorter than 4 feet, they are subject to drastic variations in sonic performance, depending on the highly variable input and output characteristics of the two pieces of equipment being connected, as well as the cable itself (this of course, has led to the snake-oil salesmen who sell hundreds of cable types based more on bullshit than fact at ridiculous prices...).

Visit any recording venue or recording studio, and you will NEVER see ANY unbalanced connections whatsoever...NONE!!! Also, in industrial instrumentation, where low-level signals must be transmitted with absolutely no degradation, you will never see anything but balanced connections. Yet, for some strange reason, in the audio world we struggle with these hideously flawed unbalanced connections even as we are supposed to be striving for high quality sound! I find it absolutely ridiculous that unbalanced connections were not dumped many years ago. As audiophiles, we certainly need to begin to firmly reject them now!!

tom collins
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Re: questions

if i can add on a question - does this just apply to components such as preamp and amp and cd player or to speaker lines. i can't think of any balanced line speakers. please enlighten me.
thanks.

commsysman
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Re: questions

Since neither side of a speaker is normally in need of a ground, it is really irrelevant whether there is a ground or not. Most vacuum-tube power amps have a transformer output, so there may or may not be a ground present; most solid-state amps do have one side of the output circuit grounded.
PHASE must certainly be observed to ensure that the two speakers do not produce acoustical cancellations, however.

Most internal circuitry of equipment, other than power amplifiers, is not balanced and in most cases there is no particular advantage to making it balanced internally. It is when signals leave the equipment that balanced circuits are required to ensure low noise and prevent signal degradation during signal transfer. The degree to which balanced circuitry may be required or desirable within the equipment to achieve this varies according to the type and design of the equipment.

tom collins
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Re: questions

thanks for the clarification on the speakers. so if you have balanced, you don't have to spend the crazy money on interconnects?

Curly
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Re: questions

Talk to any pro sound engineer for a rock band and he/she will laugh if you mention unbalanced connections.

Mike

commsysman
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Re: questions

Please see my post under "Cables" in the forums, ref. Topic "Nice and Easy Speaker Cables".

TY

commsysman
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Re: questions

Make that ANY sound engineer for ANY stage, auditorium, concert venue, recording studio...you name it.... None of them have any truck with unbalanced.

It is only the audio-phools that have any truck with unbalanced connections (those who haven't finally gotten wise, that is, and given the boot to unbalanced for good).

Of course, in this economy, it might be unpatriotic to go 100% balanced, since it will put the entire CABLE/VOODOO/BULLSHIT-INDUSTRIAL COMPLEX out of business! Awwwwwwwwwwwwwwwww.

Basic balanced cables and #10 Alpha Stranded Hookup Wire from Mouser for my speakers powers my system; nothing from the Voodoo Industry. Sounds fantastic!!

commsysman
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Re: questions

Exactly!!

Any ordinary balanced cable that uses metal-shell XLR connectors and standard AES-EBU 3-conductor cable sounds precisely the same as EVERY other one; no exceptions! You can make your own easily; High-quality Deltron XLR connectors are less than $4 each, if you want to make your own, and high-quality cable is not very expensive either; easy to make your own if you can solder, or commercially fabricated cables are not very expensive either.

I use light green or grey Gotham Audio GAC-2 cable, which costs about one dollar per meter and comes in about six different outer rubber jacket colors. This is very good quality.
MCM Electronics has 100 feet of a similar type for $47.95. Most pro audio stores list it as "microphone cable" (double-shielded, 2 conductor).

ZZOUNDS has a 250-foot spool for $134.95; listing code CBIMLSPL under "microphone cables/raw cable". I have had very good luck with ZZOUNDS; good quality and service.

Mouser Electronics lists Deltron XLR connectors, which are very very good, at about $4 each or less ( male; mouser p/n 174-7133 or Deltron p/n 705-0300...female; Deltron p/n 704-0300). Mouser is also a very good company, and I know they have microphone cable, but their wire and cable listings are arcane...a bit mixed up.

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