Unbalanced to balanced circuit

You can't do that. For you to be able to benefit from a balanced amp you need (a) a balanced source, (b) a headphone with balanced cables. If you don't have any of these your balanced amp is no different from an unbalanced one. Which is why balanced sources are worthless for any but the cable freaks.

Can you use a transformer or inverting opamp to get your inverted signal(to go with your original signal)?

I'de like to see your spice results.
I'm trying to learn Pspice myself.

DRV134 is the easy, foolproof way.

LOL worthless. try telling almost the whole pro recording industry that. balanced isn't just for 'cable freaks' although i'm a self confessed one. the pro's usually aren't even into cables they're into the gear that sounds good. And going balanced is a good start. Before I even got into cables I learned the wonders of balanced audio. SOOOO much lower noise. and the dynamics are to die for. another plus is if you are running your rig near any RFI balanced is much less prone to noise created by computers etc. LOL balanced only for cable freaks

DRV-134 for the simple and cheap. Gand total for 2 channels: probably around $40-50 all things told, about the same as a cmoy! The disadvantages are that this puts 3 more opamps in the signal path, adds gain to a system that probably already has too much, and occasionally has some voltage offset on the outputs (may require coupling caps which adds to the price...)

Next step up (or step down if you'd like to talk about voltage gain ) is a transformer:
link
An inexpensive 10K:600 ohm transformer. Be sure your source can drive 10K-ohms (most can, but double check). Wire the single ended input from 1 to 3 (dont ground the center tap on the primary), and the balanced outs across the outputs as shown. Wire a 620 ohm resistor across the outputs (+ to -) to insure proper loading.

The advantage of a transformer is that it has NO "active" distortions, dosnt require a power supply or batteries (which is where you may break even compared to a cmoyish drv-134) and you can get some control over voltage step-ups&downs.

NOTE! the transformer linked above will reduce the signal level by a factor of 4. IMO this is to your benefit: most prior attempts to "bridge" 2 channels of a headphone amp to make a balanced amp on the cheap have resulted in abysmal failures from too much gain! Edcor makes a 10K:10K transformer that has only 0.5dB loss (basically nothing). If you do get the 10K:10K transformer, the loading resistor will need to be different.

The next step up after that is just getting a source that has a balanced output native from the DAC chip, or phono-cartridge coils. Sorry about your wallet.

THAT1646 (I think I have the right #) is also a nice clean way to create balanced outs from SE input.

pin compat with SSM2142, more or less.

I plan to build one myself

I thought the reason the "pro" recording community was using balanced components was due the fact they use extremely long cable runs and the equipment/cables are susceptible to RFI and other "noise". Also don't they use most of the cables for recording, so you;re dealing with low-level signals (such as mics) and any noise can greatly distort the signal... where as we "output" signals, which are less susceptible to noise?

So from my thinking, when using balanced audio for our uses (very short cables, and outputting signals/sound) balanced might make a difference, but it should be very very small, no? Especially considering you have to make your entire system balanced $$$$. Like I said in another thread, trying to achieve that last 2% or so in signal quality.

I need balanced senders in my stereo setup.

why?

my receivers expect it. my amp's input is balanced but more importantly, the thing inbetween is also balanced (a rane crossover for mains and subwoofer). its NICE to stay single protocol all the way thru

not only that - but things that want +4db level bal inputs usually want 'hot wires' running to them so even if you ignore the fact that the 2 wires may or may not originate from a bal line driver, it still needs to be 'higher voltage' than the consumer 2v semi-standard.

pros like to run hot at the sending end and attenuate down (lowering picked up noise, as well) at the receiving end. so its important to be able to send a hot signal to the next stage or box along the chain.

yes, even if its only a 2' hop.

its not always about CM noise rejection.

Sorry for the OT

balanced is used for more than recording in the studio and a hotter (but not clipping) signal is the ultimate aim for production generally and the result of balanced is exacltly that; a hotter signal, but with a lower noise floor. it is prevalent in post production a well; and there are much shorter cable runs there. (probably just as much RFI though) yes RFI rejection is just one of the benefits; and we arent just talking about HP cables here in pour case are we?? the balanced HP cable is just the end of a chain. Balanced line level from source->(low level signal)->pre-amp->(slightly hotter signal)->AMP->(still pretty low level signal really)->HP so a 'hotter' signal with less noise is always a plus. and forgive me if i'm wrong, but arent we mostly in the business of the last 5-10% here 90% of the time. I would think that nearly all 'tweaks' would fall under this category. Of course there are SOME dramatic improvements but given a decent SQ to begin with, there really is only that last 10% to work with. in my small logic studio rig, I use the balanced ins on my RME fireface interface/dac for recording synths, vocals (not so much vocals) and ambient bibs and bobs, but also drive my active monitors with balanced XLR outs. This is a mac based setup, but I cant imagine the RFI would be too huge and I have phantom power on most devices in the chain anyway. Sometimes due to monitoring and routing I need to switch to single ended operation to use a single ended element in a mix; and I can tell you the difference is quite noticeable; even after volume matching to adjust for the decrease in gain (about -10db in my system). So while a quality single ended design can sound wonderful; IMO balanced is superior in every way. except maybe price point. bit in this case; GO DIY FTW

There's a world of possibilities. Here's one of the simpler, a single JFET inverting preamp. The distortion and output impedance is a bit high, but many have built this kind of amp for their gainclones and liked it. It's called UNO. Gain is set by R4. Building a Jfet pre amp for a Gainclone chip amp.



Or an improved version with CFP.