AR3 and Tube Amps

[Guest]

Greetings

Here's one I haven't seen discussed here.

I was wondering if anyone has used tube amps to drive the AR3's.

How much Tube power would it take to drive them efficently?

I know that they are 4 0hm and do require some power to really

push them properly!

Thanks

Brian O

[Guest]

I am sure there were many Dynaco st 70's driving the 3's years ago but I think they would not bring out the 3's full potential. If I were to run tubes I would probally bi- amp them and drive the mid/ highs with a tube amp and the low freq.'s with a good powerful solid state.

[Guest lmrosenthal]

If I remember correctly, wasn't the AR3 produced from about 1958 to about 1969? If so, then at least for part of the production run of the AR3, the only amps available would have been tube amps, no?

Of course, I could be wrong here, so maybe the best answer should come from Tom Tyson or Ken Kantor.

Regards

Larry

[Steve F]

>

>If I remember correctly, wasn't the AR3 produced from about

>1958 to about 1969? If so, then at least for part of the

>production run of the AR3, the only amps available would have

>been tube amps, no?

>

>Of course, I could be wrong here, so maybe the best answer

>should come from Tom Tyson or Ken Kantor.

>

>Regards

>Larry

Larry,

You're right on the button here. The 3 was introduced in 1958, and effectively discontinued when the 3a arrived in late '67 (although AR more or less continued to offer the 3 "for those listeners who prefer it to the 3a" for about another year or so). So, yes, the amps that existed at the time of the 3's introduction were tube amps.

I suspect, however, that this thread is more about the "audiophile" aspect of modern tube amp sound when coupled with a vintage AR-3, and the resulting sound that might come from that combination.

Steve F.

[Guest]

#### Boneske---

I used two pair of AR3's and one pair of AR2a's in my system between 1973 and 1986. I drove one pair of

AR3's with McIntosh 60 watt mono tube amplifiers, the other with two Dynaco Stereo 70's in the mono mode,

and the AR2a's with two Dynaco Mark III's, which were 60 watt tube amps, also. These amps had plenty of

power to drive the AR3's and the AR2a's. I never heard a system sound as good as mine during those

years. The low frequency output was fantastic with the six AR woofers. Many tweeters and midranges failed through the years, though and when my sons grew to be teenagers, the constant on and off for the amplifiers cost too

many tube failures. For a brief time, I tried a Phase Linear 400 to drive them all. I remember it would trip

a 15 amp breaker when driven hard. The sound quality was horrible compared with the tube amps and cost

several more midrange drivers. Finally, I was lucky enough to find three Hafler DH-200's, which have plenty

of power and sounded as good as the tube amps. I use the Haflers to this day, but replaced the AR's with

Infinity Quantum II's and III's, which suck up gobs of power, but sound unbelievably good.

I have a "vintage system" set up, however, with a pair of AR3a's, Dynaco Stereo 70, Dynaco PAS3 preamp,

and an AR turntable. Most young people can't believe stereo sounded this good in the 1960's!!

[tysontom]

It is very true that the AR-3s were introduced before the formal introduction of commercial solid-state amplifiers, and most likely most AR-3s were used with tube amplfiers, such as the Dynaco Mark III and Stereo 70, as well as Marantz, McIntosh and Harmon-Kardon designs. The AR-3, however, was a low-impedance, low-sensitivity loudspeaker, and it therefore demanded a great deal from a power amplifier. With the level controls turned up high, the impedance would drop below 2 ohms. This could be a challenge for small-power tube amps.

When Acoustic Research performed the numerous AR-3 live-vs.-recorded demonstrations with the Fine Arts Quartet and Gustavo Lopez, the amplifiers used in those sessions were Dynaco Mark III 60-watt tube amplifiers. That system worked extremely well. In New York's Grand Central Terminal, above the AR Music Room, AR-3s were used each Holiday Season to play Christmas music -- above the den of noise in the GCT. Amplifiers used were Dynaco Mark IIIs. In the 1964-65 time period, several magazines chose the "top hi-fi systems," and most of these magazines chose AR-3 speakers used with tube amps. For example, *Popular Science* chose AR-3s with a Dynaco Stereo 70 amplifier as their top system (PS had chosen the AR-3 as the best loudspeaker from among nearly all popular speakers of the day), *Bravo* magazine chose AR-3s and the H-K Citation II (60-watt) tube amplifier.

It is quite interesting that one of the first high-power solid-state amplifiers was designed partly around the need for reliable, high-current output power. This was a 200-watt-per-channel silicon-transitor, solid-state design by Mattes Electronics. Most solid-state amplifiers during the infant years of this design were geranium-based devices, nortoriously unreliable. An article was published in the December, 1965 *HiFi/Stereo Review* issue entitled "What the Music Demands of the Amplifier," written by Robert Berkovitz, then Manager of Product Development for Mattes. In this article Berkovitz (an absolute genius who went on to AR and headed up product-develop design there) describes, quantitatively, how much power is required to reproduce a live piano, and he showed large peaks on an oscilloscope from the output of a high-quality condensor microphone, and then these same peaks that were reproduced from the AR-3 being used to demonstrate the need for this power. The most interesting part of this entire article, however, was not the peak-power demands of the music so much as the accuracy in which the AR-3 reproduced the piano, as shown on the oscilloscope traces. Everyone in attendance, and those who reported on this test, were amazed a how accurate this speaker was in reproducing the live piano.

--Tom Tyson