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confusion about balanced preamps (long...)

Posted by Ralph (M) on May 14, 2003 at 16:53:16

In Reply to: Atmasphere Pre-amp and Balanced lines posted by Randy Rhone on May 13, 2003 at 13:52:54:

The MP-1 and the MP-3 are designed to take advantage of all the benefits of differential circuitry and our (patented) direct-coupled output. The direct-coupled output allows the preamp to overcome interconnect cable problems while similtaneously eliminating a prime difficulty in 99% of all tube preamps in existance: the output coupling capacitor. In this way the preamps can play deeper bass, without the tubby quality that most tube preamps exhibit to some degree, all the while retaining high speed and relaxed presentation (sorry for the plug, but in a nutshell, that's the design goal).

All phonograph cartridges, save for the Decca, are balanced sources, even most cheap ceramic units. Setting up most turntables, even a BSR or Garrard from 30 years ago, is a simple matter.

The real issue seems to be: 'what about single-ended auxilary sources, such as a tuner?' Such sources can be accepted at either AUX input (but requiring an adaptor or cable with an RCA connector on one end and an XLR on the other, or by using the MONITOR inputs, which have RCAs already.

In either case, the line section of the preamp will convert the single-ended input to a balanced output without degradation. The advantages of the simplicity of the balanced line section are retained. The only weakness to this approach is not really a weakness at all: the single-ended sources' own lack of being balanced. IOW, there is no degradation by using a single-ended input. Its just that, all other thing being equal, a balanced source will sound better, but better in a way that a single-ended source cannot improve upon.

BTW, the philosophy of both preamps is that they function as stand-alone phono sections with a volume control. Take away the front panel switches and that is exactly what they are, no more or less, as such a unit (from us, anyway) would have the direct coupled output to allow control over the interconnect cable. So we merely added enough switches to also allow the use of line-level sources. We tried to be as purist about it as possible and so far we've found no preamp that sounds better, save for the issue that a balanced power amp must be used (otherwise the full capabilities of the preamp are not realized).

Sorry to be blowing my own horn here, but we've gotten a lot of this sort of confusion over the last 13 years since the preamps were introduced. I hope this clears some things up.

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