SAE Mark II Power Amplifier

It takes a lot of courage for a new company to launch an amplifier like this at time when most manufacturers are courting the mass market with budget-priced receivers, and Marantz is pretty firmly established as the Rolls Royce of audio electronics.

The SAE Mark II has, nominally, the same performance specs as the Dynaco Stereo 120, yet it costs twice as much as a factory-wired Stereo 120, and about 2½ times as much as a Stereo 120 kit. Is the SAE really worth the difference? And how does it compare with some other $400 amplifiers? Well, it all depends.

To begin with, the SAE and the Dyna aren't quite as similar in characteristics as the specs would sug gest. Although both are rated at 60Wpc into 8 ohms, and both will deliver a shade over 100W into 4 ohms, the SAE is capable of delivering around 40Wpc into a 16 ohm load, whereas the Dyna's output drops to around 25 watts with a 16-ohm load. This is a small difference in terms of listening levels, but it does allow the SAE to exercise somewhat greater control over a 16 ohm speaker system. The Marantz Model 15 has roughly the same output character istics as the SAE, so either of these would be equally suitable (or unsuitable) for driving a 16 ohm, low-efficiency system like the KLH Nine.

A basic difference between the SAE and its solid-state competition, though, is its ability to operate with both channels essentially in parallel (actually, they're closer to being in a push-pull-series configuration) for monophonic operation. A third input jack on the front panel feeds the amplifiers with the out-of-phase signal that they need for this mode of operation, and the two "hot" outputs are then used as the loudspeaker connections. Input receptacles are phone-type rather than the usual RCA phono variety, and appropriate input cables are supplied with the amplifier. In the mono hookup, the amplifier's nominal output impedance is 16 ohms, and available power (at rated distortion) exceeds 120 watts—more than enough to drive even a KLH Nine panel to overload.

One of the features claimed for the SAE is an extremely effective overload-protection circuit. If the output transistors are badly overdriven, due to an output short or a severe signal overload, the transistor outputs are electronically switched to high-value load resistors inside the amplifier for five seconds, after which time a sensing circuit checks to make sure the short isn't still there before it switches back to the speaker terminals. Further protection against accidental shorts is provided by the use of insulated and widely-spaced output terminals.

After we completed our other tests, we applied some overloads in an endeavor to pop something and are happy to report that we had no luck. Possibly, the SAE could be damaged by running it for a prolonged period at overload levels into a shorted speaker load, but this is an unlikely eventuality. We do not advise anyone to show all his friends how effective the protection circuit is, though, to paraphrase Dynaco's David Hafler, protection circuits are like parachutes; they usually work, but you're safer if you don't test them.

Internally, this is one of the most beautifully constructed amplifiers we've ever seen. It is such an impressive-looking piece of work, in fact, that when SAE made up a sample unit with a lucite top cover to show off wiring to prospective dealers, they started getting orders from consumers for other "demo" samples. The lucite-topped model is now available on special order for an additional $10.

So, the specs look good, the safety circuits seem to work, the construction looks fine, and the warranty (five years) suggests considerable confidence on the part of the manufacturer. But how does the SAE sound?

We compared the SAE Mark II with four other amplifiers: a Dynaco Stereo 70 and a pair of Marantz Model 9s (two of the best tube-type amps), the top-rated (to date) Dynaco Stereo 120 transistor amp, and one of the costliest and most highly-rated Marantz solid-state units, the Model 15. Listening tests were made using a variety of representative loudspeaker systems.

Generally, the SAE Mark II gave the impression of being as close to absolute perfection as any ampli fier we have ever heard. On all types of speaker systems, its overall sound was extremely smooth and transparent, without a trace of perceptible hardness or graininess. Lows were very deep, tight and solid, with no sense of restriction due to the amplifier. Recovery from brief, moderate overloads appeared to be instantaneous, but a severe overload was found to cause complete loss of signal for several seconds, due to the operation of the protective circuits. So don't have a heart attack if an accidental massive overload kills the sound; count slowly to 10 before starting to worry.

One other thing that may be a source of unnecessary worry: when the amplifier is first turned on, the speakers emit a slight "phut" sound. This is normal, and is no cause for concern; it's just the power supply capacitors charging up.

On dynamic-woofer loudspeakers, the SAE shares with other good transistor amplifiers the ability to produce deeper, tighter bass than any tube-type amp of comparable power rating. Similarly, it seems to produce smoother, more integrated sound from multi-way (more than two-way) speakers than does any tube-type amplifier. On all-dynamic speakers of 4 to 8 ohms impedance, the SAE's low end was noticeably tighter and better-defined than that of the Dyna Stereo 70, it was a little better than that of the Marantz 9s or the Dyna Stereo 120, and was just a shade deeper-sounding than that of the Marantz 15.

Through the rest of the range (and again through all-dynamic speakers of 4 to 8 ohms), the SAE sounded similar to the Marantz 9 and the Dyna Stereo 120, but was very subtly more transparent-sounding than either of these. By comparison, the Dyna Stereo 70 sounded somewhat "sweeter" but had a bit less detail, while the Marantz 15 had a quality of crispness that bordered on hardness. All in all, we felt the SAE to be better-sounding with low-efficiency dynamic speakers than any of the other amplifiers it was compared with, although it must be emphasized that in no case was the difference a dramatic one.

High-efficiency dynamic systems revealed the same differences, although to a somewhat lesser degree. With these systems, the main difference between the amplifiers were at the low end, where all of the solid-state units yielded perceptibly tighter lows than the tube-type amps.

With speaker systems combining electrostatic tweeters with dynamic woofers, the low-end differences between amplifiers were as noted above, but high-end differences were somewhat more pronounced. The Marantz Model 15 that we were using, for example, sounded almost annoyingly hard, the Marantz 9s and the two Dyna amplifiers were musically sweet and very transparent, while the SAE seemed equally sweet but with a shade more transparency and detail.

On KLH Nine full-range electrostatics, the pair of Marantz Model 9 amplifiers won hands down, yielding tighter, deeper bass and generally more natural and "easy" listening quality than any of the other amps. To our surprise, though, the Dyna Stereo 70 and the SAE were indistinguishable from one another on the KLH Nines except at very high levels, when the SAE's superior power-supply regulation allowed it to retain better detail through brief periods of peak overload. In view of their price difference, this is something to think about. The Stereo 120 and the Marantz 15 shared the SAE's detail at high levels, but both of these tended to make high-level disc tracking distortion rather more unpleasant than the other three amps.

Listening to monoblocks
Note that the foregoing tests were made with the SAE in its stereo mode, which limits its power capacity when feeding a 16-ohm speaker system. Since SAE was thoughtful enough to send us a pair of Mark IIs, though, we concluded our listening tests with both of these connected for monophonic use.

The difference was more dramatic than we had expected it would be, particularly on the KLH Nines. Highs were a shade sweeter, the overall sound was somewhat more detailed-something we would not have thought possible—and the low end was dramatically improved, becoming even deeper and more solid than it was when fed by the Marantz 9s.

With other 4–8-ohm speaker systems, the advantages of the mono hookup were much less noticeable, which leads us to speculate just how much of the sonic improvement we have noted when using top-notch solid-state amplifiers is due simply to the amount of power they are able to deliver to the loudspeakers.

All of the solid-state amps we've encountered seem capable of feeding more usable power to the speakers than do tube-type amps of equivalent power ratings—perhaps because of their lack of an output transformer or perhaps because they tend to have better-regulated power supplies. But use a good transistor amp in a situation where its power output capability is less than that of a good tube amplifier, and much of the transistor's superiority seems to vanish. There are, of course, other factors to be con sidered. Solid-state amps, by and large, have a higher damping factor than tube amplifiers, so a given amount of available power will tend to exercise greater control over the speakers, which may explain some of the improved definition in their sound. But generally speaking, the more that a transistor amplifier's distortion at any given power output level approaches that of the best tube-type amplifiers, the more alike they will tend to sound.

In a nutshell, then, the SAE Mark II is, under most conditions, the best-sounding solid-state amplifier we have heard to date, and in view of its construction and its rather liberal warranty policy, we would say it is well worth the money if you're looking for something with the quality, if not the prestige, of the best of the Marantz units. It is unquestionably a bit more listenable than the solid-state Marantz amplifiers we have heard, and will drive most speakers at least as well as the best of the tube units.

SAE (Scientific Audio Electronics)
1749 Chapin Road
Montebello, CA 90640