Thank you!
I am actually in the middle of writing an article on a blog, which will include the NuForce HA-200's (x2).
However, here is a sort of extract/some info about balanced audio from my article (this is very much condensed and not meant to be in-depth).
First, when we talk about stereo, we mean Left and Right channels. Specifically: Left Negative, Left Positive, Right Negative, and Right Positive. This is known as polarity, and each channel has a phase, positive and negative. (For sake of clarity lets define each polarity as L+, L-, R+, and R-).
To make a stereo amplifier, you need to address each phase. Without going into all of the numerous topologies on how this is done, lets just assume that a stereo amplifier will amplify each phase of each signal.
So, this then brings us to two ideas of amplification, single-ended (SE) and balanced:
Single-ended:
In the most general cases, most stereo amps amplify by bridging the incoming L+ and L- phases together, amplifying both phases simultaneously, and ditto R+ and R-. The connections, input and output, share a ground signal (wire) in the cables itself and in the circuitry. (That is to say that the L and R channels share the same ground wire).
This means that most stereo amps will have a design that amplifies the left and right channels almost simultaneously, but technically are internally split as L+/L- and R+/R-.
In the audio world, this is collectively known as a single-ended design, and is often a one-box solution.
Now, you can have SE designs in which there is one amplifier powering left and right channels together, two amps for each channel, or, uncommon, one amplifier per phase of per channel. However, due to the grounding of these amp designs, they are still single-ended. The latter two, more extreme, designs are considered to be the more superior but it is not often seen in SE amps. It is, however, popular in balanced designs.
Balanced:
The next up from SE designs in stereo amplifiers is, first, that the circuitry design has grounding per each channel, not combined. That is true of the I/O, and the balanced cabling, where the left and right channels have completely separate ground wire per channel, all the way to the termination (2.5mm TRRS, 4-Pin XLR, 2x 3-Pin XLR, 4.4mm TRRS Pentacon, etc). This is the first BIG difference between SE and balanced amps, and why special cabling is needed*.
From here, you have two popular balanced amp topologies:
- Bridge-Tied Load/Bridged Transformerless:
Here you have two amplifiers, where one amp is fed L+ and R+ but receive the phases completely separately. Ditto the second amp which receives the alternative signals, L- and R-, again, having the incoming inverted phases separately.
This is, technically, a superior design as each amp has a job to do and crosstalk and noise between channels is lowered.
This design typically has the advantage of doubling voltage and swing (electrically), meaning more power which should be read as 'this amplifier has more headroom to play music at different loads'; ie better at playing the nuances, varying volume differences, and changes in a piece of music.
These designs are usually found in one-box solutions.
- Fully differential balanced:
This is the cool balanced design, and is what 2x HA-200's can do.
Similar to BTL, but here there are four amps dedicated to each phase of each channel. Each amp receives each phase separately too. Thus:
One box for Left channel: 1x amp for L+, 1x amp for L-
One box for Right channel: 1x amp for R+, 1x amp for R-
Though technically this is also doubling voltage and swing, it can be seen as quadrupling depending on amp design. However the magic here is that because each phase is being treated individually, even more noise and channel crosstalk is reduced, more so than BTL (again, depends on the design).
Such amps can also be found in one-box solutions but they are very large, but it is more common to see them in two-box designs, the latter being referred to as monoblock amps (one box is for L, the other R). (Some crazy amp designs will have a four box solution too).
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*WARNING!
Do NOT modify or use adpaters on SE cables into balanced; you WILL damage or short your equipment. That is because SE wires share a ground wire.
Balanced cables do not, so can be used in balanced gear, and with adapters SE gear too, without worry.
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Lets relate this to the HA-200.
One HA-200 has two internal amps inside. In SE mode, each amp is bridged, hence normal stereo mode.
However, the amp circuitry allows SE ground cables and balanced cables (how is too much for writing here, but is itself an interesting read and topic).
When you get two HA-200's and use balanced inputs and output cables, the two internal amps per box are no longer bridged; they are treated as each individual amp, dedicated to each phase of each channel.
What makes the HA-200's special is that it includes two design topologies per box, and when you have two boxes you have the only monoblock, fully differential amp system that is cheaper than any alternative on the market, with loads of power.
It is this that makes the NuForce HA-200 interesting.
Hope that this makes sense and helps ^^
Bought 2x HA-200's as a base for my reference; powerful fully differential balanced monoblock amplifiers. To even get close to the power, and sonics, I would have to increase my budget massively. It is true to say that having actual four amp's powering each phase of each channel is insane, and at this price unheard of.
The Schiit Audio Jotunheim was what I was going to pay for at £420, but that is not differential (yet still incredible for what it can do). It has 4-Pin XLR, one volume pot, one power wall plug, and one box design. Its topology is also very, very cool (circlotron). You can add a DAC (or phono) too for a bit extra, but I do have some records at DSD, and my digital audio player (DAP) has a superior DAC to the Jot (though not the full output Voltage). The 2x HA-200's has more power, fully differential, and much cheaper: via Massdrop it is around £370 (including shipping and customs to the UK; approx customs cost worked out using a duty calculator).
Will use my current Onkyo DP-X1 DAP's balanced out (Double Helix Cables 2.5mm to 2x 3-Pin XLR cable) as a DAC for the short term; I am getting the Oppo Sonica DAC with it's latest fully balanced ESS DAC chip and higher Voltage output later this year. I already have most of the cables necessary (three all pure silver DHC cables), just waiting on a few adapters (4-Pin to 2x 3-Pin XLR DHC Comp4 adapter, and an Audeze EL-8 Zync adapter for a certain DHC cable I have). Will get some single DHC 3-Pin XLR silver cables (x2) down the line too when I get the Sonica DAC. (I am not upgrading my iFi Audio iUSBPower 1st Gen to iUSBPower 3.0, or iPurifier to iPurifer 2, as the originals are still very good, but that might happen near the end of the year. My iFi Audio Gemini dual-headed USB cable will be used however).
Even with the extra adapters (some of which was already incoming), I am still paying less than the Jot, and I would have, from a technical standpoint, a much more sophisticated system due to fully differential design topology. Sure, the Jot may or may not sound better, but the 2x HA-200's will be more resolving power wise with different sources, and allows me to play with more headphones of varying power requirements. I would have to deal with volume matching but I could max out the 2x HA-200 volume pots and use a DAC as volume. Having two power wall plugs would also be annoying (a third with a proper DAC down the line). No 4-Pin XLR output is itself annoying too but the adapter I am getting takes care of that.
My current actively used headphones are: - Audeze EL-8 Titanium (2016 drivers as standard) - Meze Audio 99 Classics Walnut Silver
Both have uncommon DHC Molecule Elite 22AWG 4-Wire pure silver cables with 2.5mm Eidolic terminations, intended for DAP use. However, I have a special, one-off DHC 4-Pin cable too, originally to be used with a balanced 4-Pin XLR amp. (That's why I am getting the 4-Pin to 2x 3-Pin XLR adapter, and Audeze Zync adapter, for this special cable, to use with the 2x HA-200's). I am also trying to score a Focal Elear at a cheaper deal (refurbished), and save up for the Sony MDR-Z1R in the distant future (or whatever else dethrones it whilst I wait).
Essentially, I was slowly building up a framework to get to this point (invested over years in great cables from the get go so that I would not need to upgrade soon, got two of three headphones sorted, and pour the rest of my investment into desktop amp and DAC this year); after years of planning and watching out on new products, my proposed system should last me a long time ^^ 2x Optoma NuForce HA-200's + Oppo Sonica DAC, running pure silver cables, should be a mighty system d^^b
Once I have the desktop side sorted, I can just sit back and invest in any cans I like over the upcoming years.
Can't wait!!!