[gkinberg]

Hi Frank, I was going to PM this question to you but then thought that this might be of interest to the forum.

Would it be possible, impossible or just costly for you to retrofit a stock ultra 550 (or something similar) with a balanced circit and XLR inputs so that it was now a truly balanced amplifier? One of the resons I ask is because I am having trouble finding a balanced, hybrid amp with around 200 watts for a "reasonable" price. 

[avahifi]

A "true" balanced line power amp would have four separate internal channels; left plus, left minus, right plus, and right minus.  Obviously there is no room inside our big amplifier chassis for four separate Fet Valve channels.  Two Fet Valve hybrid channels simply fill the space inside.  Thus your request for this is very much impracticable

You can of course simply use two Fet Valve 400R or 600R hybrid amps, each bridged mono with our Insight+ phase inverter bridge.  This will give you two balanced line amplifier channels at only twice the cost of a single stereo amp plus the cost of the bridge.

Most so called balanced line amplifiers actually have two internal stereo channels and input circuits to convert balanced line to single ended and output circuits to convert single ended back to balanced line - - - two more active circuits that can't do anything good for you except add more distortion.

We actually can build a true balanced four internal channel Synergy solid state amplifier in one chassis, but since that will nearly double the price, I doubt if many would want to pay for it.

Regards,

Frank Van Alsine

[gkinberg]

Thank you Frank for your thoughtful explanation. It is frustration that just because an amp has XLR inputs doesn't mean that it is a truly balanced design. I suppose you have to contact the designer to be certain.

[trebejo]

If you have a look inside the chassis (either first-hand or via online reviews) you can tell when an amp is not truly balanced, since you'll probably not find "four of everything".

Frank's phase inverter does the trick. I think you can probably take the two output terminals from the phase inverter and turn them into a single XLR.

Avoiding XLR connections (nice as they are...), the phase inverter with a pair of amps gives you the monoblock advantage and the balanced advantage. And of course, you get to buy two amps.

[CrazyBlue]

A "true" balanced line power amp would have four separate internal channels; left plus, left minus, right plus, and right minus.  Obviously there is no room inside our big amplifier chassis for four separate Fet Valve channels.  Two Fet Valve hybrid channels simply fill the space inside.  Thus your request for this is very much impracticable

You can of course simply use two Fet Valve 400R or 600R hybrid amps, each bridged mono with our Insight+ phase inverter bridge.  This will give you two balanced line amplifier channels at only twice the cost of a single stereo amp plus the cost of the bridge.

Most so called balanced line amplifiers actually have two internal stereo channels and input circuits to convert balanced line to single ended and output circuits to convert single ended back to balanced line - - - two more active circuits that can't do anything good for you except add more distortion.

We actually can build a true balanced four internal channel Synergy solid state amplifier in one chassis, but since that will nearly double the price, I doubt if many would want to pay for it.

Regards,

Frank Van Alsine

Frank and members,

I often wonder about the real world, real ears advantages of a balanced design, and how audible they are.  I've never heard an A/B comparison, and only a few balanced setups in store auditions.  Fancy styling and boat-anchor chassis aside, this seems to be one of the actual design features of many ultra high-dollar amps and preamps, and lots of folks sing the praises of truly balanced stuff.  But when asked why they always quote the standard technical jargon about lower noise and more dynamic range.  The words "It sounds noticeably better" are seldom if ever part of that spiel.  Am I actually going to hear not only a difference, but a multi-thousand dollar difference?  Or is this something that's mostly going to be experienced on paper and in the head?

Truly curious, not being facetious. 

[gkinberg]

As a follow up, I contacted Classe and parasound as these companies have amps with balanced inputs that I could potentially afford (even though I usually look on the used market). The gentleman from Classe assured me that nearly all balanced designs get summed at some point in the amp and that it was nearly inconceivable to have an amp that was balanced from input to output throughout its design. The fellow at parasound told me that the A21 wasn't balanced and that I would probably need to look toward a professional product to get something truly balanced.

Just thought this was interesting and thought other circle members might appreciate it.

Garth

[CrazyBlue]

So going that route, you're paying significant money for extra, unneeded circuits (unless you actually have insanely long cable runs and truly need the XLR) with the potential to introduce noise and distortion? 

Hmmm...

[CrazyBlue]

Starting to wonder, if there is an audible difference, how much of it is simply due to the XLR output usually being hotter.

[avahifi]

All other things being equal, a balanced line set up will be 6 dB louder as the voltage swing of the plus and minus signals sum and thus double.  Lots of folks hear louder as better, but you don't need balanced line for that, just a volume control. 

Of course all other things are not equal as described above in this thread.

Frank Van Alstne

[festuss]

I have been using 4 P500 AVA OmegaStar EX driven by 2 Ultra Hybrid phase inverters  truly remarkable.  The AVA phase inverter method is the way to go!  no noise, more power, and effortless ability to make anything sound incredible.