Pre and Amp Suggestions

Ralph, I was pretty shocked a while back when I read one of your posts that asserted that if components were properly designed to the balanced standard there would be no difference between interconnects.  Since then I've wanted to ask the obvious question -- why don't all manufacturers who produce preamps with fully balanced designs adhere to the standard?  Is there a downside or trade offs to doing so?  I've been scratching my head over this one for a while since it doesn't seem like it costs much more to adhere to the standard, especially if you're going to the trouble and expense of building a fully balanced unit from input to output.  What gives???

spinaker01 - After hearing an X250 in my space, that's what did it for me.  I then sought some pass options and after deciding not to go with the int60 (again by all accounts is superb) I went with XA100.5's. 

I am now on a pre hunt, but after those two large purchases I'm in no hurry.

 Since then I've wanted to ask the obvious question -- why don't all manufacturers who produce preamps with fully balanced designs adhere to the standard?  Is there a downside or trade offs to doing so?  I've been scratching my head over this one for a while since it doesn't seem like it costs much more to adhere to the standard, especially if you're going to the trouble and expense of building a fully balanced unit from input to output.  What gives???

@soix The problem is that its not easy to do. So most manufacturers just don't.

With power amps its pretty easy to support the standard, but with preamps its hard. This is because of the requirement to float both the inverted and non-inverted aspects of the signal. There aren't many ways to do that! In the old days when tubes were the only game in town, it was done with output transformers whose secondary (the output side of the transformer) was meant to drive a 600 ohm load. That satisfied the floating requirement and also the low impedance requirement.
When solid state came along things didn't change much in this regard, mostly due to the requirement to float the balanced signal. So in the recording/pro audio world, there are still a lot of products that have output transformers even though they are solid state.

Transformers of this type have much wider bandwidth than output transformers do on power amps, so they can be much more transparent! Most LPs and CDs in your library had a transformer somewhere in the recording signal chain. But such transformers cost something, although to anyone in high end audio, really not that much. You can use line transformers (for a few hundred dollars) with conventional single-ended preamps with excellent results if you set things up right, and have all the advantages that balanced line cables have.

So the biggest single 'short hand' that manufacturers use to cut corners is to dispense with the floating aspect of the signal; most are in the business to make money more than they are to see how far they can push the art, so adding an output transformer is often seen as an extravagance that eats into the bottom line. They may also think that the transformer is less transparent, and if it were only in that regard I agree, but if the cable starts to introduce a coloration or lack of focus or the like, maybe that's not so true.

The only other way to do it where ground is ignored is the way that we do it, which involves a circuit called a Circlotron. This allows for a direct-coupled balanced output that is floating with respect to ground. I think the problem here is that to do this right, you have to get a lot of things right from one end to the other, and to make matters worse for other manufacturers, my company controls the patent on this process.

So the competition has to use output transformers, infringe our patent, or just not support the standard. The problem with the latter is the baby with the bath thing; if you ignore too many aspects of the standard you also lose a lot of the advantages it brings.
I've always seen the cost of high end cables as a hidden cost of any single-ended preamp- in some cases I've seen them cost more than the preamp! Balanced preamps don't seem to cost any more than their single-ended competition in practice (although in our case we price according to a formula and most companies price to what the market will bear, so our gear tends to be less expensive), so the advantage of not having to buy expensive cables to make it all work would *seem* to be an advantage. But in 29 years of making balanced preamps, my experience is that most audiophiles don't care about the cost of the cables- I totally got that wrong.

Wow. Just wow. That was very interesting and informative Ralph. Thank you! I don’t mean to pump your stock here, but given what you said and my limited knowledge of electronics, there seems to be little or no downside to employing a Circlotron-type design -- except that other manufacturers would have to pay you to use it. Um, am I missing something here? (Obviously there are a lot of other circuit design and parts quality stuff that will have a huge impact on ultimate performance as well). Seems like kind of the advantages of your OTL amp designs but maybe without the heat and tube expense given the small amount of gain needed in a preamp? Or is that just a gross oversimplification or misrepresentation? Thanks again for your super helpful explanation!

@soix A lot of manufacturers don’t want to produce a circuit that they didn’t design, the exception being classic circuits from decades ago.

IME having a direct-coupled output at the preamp level is a boon for detail and neutrality, even moreso than at the amplifier output. The coupling caps at the output of most tube preamps are usually the most expensive that will be in the circuit. They are usually a compromise of being as large as they can be to accommodate solid state amps with a lower impedance input, while at the same time as small as they can get away with so that the inductance of the part causes the least amount of coloration. This often limits the preamp as to the lowest input impedance they can drive without loss of bass. When you direct-couple, you get the bass and detail at the same time and no problems driving low impedances. My speakers are 16 ohms and fairly efficient; I've driven them directly with my preamp and while it won't play much above a conversational level, it sounds fine and controls the dual 15" woofers with no worries.