Tube pre-amps: balanced a big deal?

You have to think in the long term, if the pre is to be a keeper. You may not need balanced output now, but what if you buy a new power amp like my Arc Ref 75 that only has a balanced input, your pretty much stuck without a balanced out on your pre.

The only tube pre-amps I am aware of that can drive 600 ohms are Atma-Sphere’s and EAR’s. Atma-Sphere’s because Ralph Karsten is an unusually hip designer, EAR’s because Tim de Paravicini does most his work in pro recording studios (including Pink Floyd’s in London), where that ability is an absolute requirement. But Tim uses transformers to achieve his balanced outputs; to achieve the ability to drive 600 ohms from a tube pre-amp without transformers is the evidence of nothing less than pure brilliance!

what is the AES standard, again? Which signal on which pins, etc? Thanks---Eric.

Pin 1 is ground, pin 2 non-inverted signal, pin 3 inverted (in Europe, pins 2 and 3 are reversed)

Ground is ignored (no signal current) for output **and** input; signal travels as a twisted pair within the shield, which is used for shielding only and no circuit return. This particular aspect of balanced operation is where most high end audio products simply don't get right; in a nutshell signal ground currents in the cable suddenly means that the cable becomes audible...

Overall the circuit will be low impedance. In older (studio) equipment, the input impedance was commonly 600 ohms (so the source has to be alright with driving 600 ohms with low distortion and no bandwidth reduction); newer equipment tends to be 1000-2000 ohms; semi-pro equipment (such as Tascam) tends to be variable and can be as high as 10K ohms.

Our balanced preamps support driving 600 ohms which very unusual for a tube preamp without an output transformer.

Note: the ability to drive 600 ohms is not the same as a '600 ohm output impedance'! This is kind of hard to do, which is my thinking about why so many high end audio manufacturers don't support the standard.

“The trick is that the equipment has to support the balanced standard, otherwise known as AES file 48. Many 'high end audio' components do not, which means that you may not realize all the benefits of going balanced.”

Spot on as usual.

Kenny.

Ralph, what is the AES standard, again? Which signal on which pins, etc? Thanks---Eric.

Balanced is great for long, long runs, otherwise for typical in home usage you wont notice anything else besides the free 6db gain.

This statement is problematic. Many balanced systems don't give you any extra gain. The real reason that balanced operation can be attractive is that the balanced line system was devised to eliminate interconnect colorations. If you've ever had to audition a cable or happen to have heard one sound better than another you know what I'm talking about.

What if you could have cheap cables that sounded as good as the very best cables which can cost over $1000/foot? Balanced operation is how you make that happen. The trick is that the equipment has to support the balanced standard, otherwise known as AES file 48. Many 'high end audio' components do not, which means that you may not realize all the benefits of going balanced. Balanced is worth it- once you've heard a balanced system properly set up, there's no going back, but Buy Beware...

Even better is no crossover at all. The Eminent Technology LFT-8b uses two paralleled push-pull magnetic-planar drivers for the 180Hz-10kHz range---no crossover!

Thanks cousinbillyl, good insight.

I try to keep things simple;
A phono cartridge is a true balanced source. The sinusoidal waveform goes up, and then it goes down. A dual differential phono pre amp, pre amp combination preserves the entire waveform. An asymmetrical (rca) pre amp references the negative (down) portion of the waveform to ground. It's a little forward to say it's thrown in the garbage. However, with careful manipulation of negative feedback, a single ended pre will restore some of the negative portion.

Once you start down the balanced path, you need to go all the way. In time, and as funds allow, you will have a fully balanced system from diamond tip to amplifier output.

Here's where the problem starts. Most speakers have asymmetrical crossovers. If possible, try to find Gauder Acustik speakers. They use a symmetrical parallel crossover. When driven by a fully balanced signal, they are truly remarkable. Salk Sound uses an almost symmetrical series crossover. If you do a search, you'll hear a recurring theme; people that own Salk speakers, rarely change.

Not sure if they are balanced, but CAT are among my favorites.

You won't really lose anything. The soundstage that opened up was due to balanced being 6db louder than single ended, you'd just have to turn the single ended preamp louder to match. We perceive louder as better, always.

Balanced is great for long, long runs, otherwise for typical in home usage you wont notice anything else besides the free 6db gain. 

I had the DeHavilland Ultraverve, it's fantastic.

Interested in hearing tubes, this seems like the best way considering what I am starting with.  Balanced connections are available on the Jolida and Schitt, not on the deHavilland, but the reviews would indicate the deHavilland is the more popular.

Hi why are you paring a tubed preamp with an integrated amp? Also at the price range your looking I would say forget about balanced. Of the three preamps you list I would personally choose the Dehavilland.