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pro amp for AR9


Joel

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I currently have a Dynaco 416 amp and Nikko Betta II pre-amp. I have had them for about a year, and they work fine. However, with some of the discussion here about pro amps, I have been thinking of switching to a new amp for my AR9's. The two amps I have been considering are the Crown XLS1000 or the QSC GX3.

Which of these two amps are better, and are either of them better than the Dynaco I currently have? One of my biggest concerns is the age of the Dynaco, vs something newer and potentially more reliable. The other option would be to bi-amp the AR9's- would the newer pro-amps work well together with the Dynaco or would I be better off with both amps the same?

Thanks.

-Joel

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If I remember correctly, the Dynaco 416 was a "souped-up" 400. I owned a 400 (built it from kit-form) and it's not a bad amp for the money. Driving the AR9's "hard" and the power supply will probably still "sag".

If you do "bi-amp", safer to go with identical amps even though different amps can be used; just more of a hassel .

To insure that phase and gain of different amps are set properly, suggest (but not required) some "basic" test equipment to do it efficiently. Remember that a bi-amped AR 9 should sound virtually identical to a conventionally-driven unit when used at low to -moderate levels.

Don't know the specifics of either of the amps you mentioned but look for the best power ratings @ 4 ohms or less AT BASS FREQUENCIES. This is where the AR 9 is most demanding from an amplifier standpoint. Both are highly regarded companys in the pro-world. Think Crown has been around longer, and QSC is considered a "better value" but in the same league as Crown.

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What is the purpose of the built-in crossover on the Crown Amp? Is that something desirable, and if not, can it be bypassed?

-Joel

Crown amps are "pro" amps widely used in PA/stage/ Sound Reinforcement / Rock concerts applications. As such, "bi-amping" & "tri-amping" mutiple bass-bins and "stacked arrays" using electronic crossovers is the norm (instead of the usual built-in passive crossovers found in speakers for consumer use).

What Crown did was "integrate" the electronic crossover portion into their amplifier products. This saves "rack space" and wiring complexity is greatly simplified . An analogy to this "concept" is the ubiquitous "reciever" vs "seperates" approach among stereo buffs. For most users, the reciever is more than adequate. But for demanding audiophiles wishing greater flexibilty, the seperate pre-amp, power amp is the way to go. Advances in technology makes it cost - effective to integrate complex crossover circuitry into a single compactchassis without suffering large performance trade offs.Below is what Crown says:

"The PureBand™ Crossover System in the XLS Series adds an enormous amount of flexibility and performance to any system. With this system, the crossover frequency is completely variable allowing the choice of any crossover point between 50 Hz and 3 kHz on 1/12 octave centers. The use of 4th order Linkwitz-Riley filters provides steep slopes for a seamless transition between high and low drivers. All of the PureBand™ Crossover System settings can be fully configured quickly and easily from the front panel using the intuitive LCD interface."

I presume this is "defeatable".

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Are Crown's XLS series amplifiers suitable for driving AR3 too? :rolleyes:

For getting the best possible bass at high playback levels, I certainly believe so . I've never owned a "modern'"amp which uses these highly efficient "switching(?)power supplies. Such designs make it possible to have huge power at low cost . I don't know how they sound @ the mid - treble frequencies though.

I believe very early "classs H" designs had either very high distortion or limited power at the upper frequency spectrum. Today's "better" designs probably don't suffer from this. I believe the majority of today's "powered subwoofers" employ this technology. If there ARE "audible" midrange to treble distortion components, you certainly won't hear them thru the subs.

I THINK ( someone correct me if I'm wrong) from a "measurement standpoint" using test equipment, these efficient designs may be "band-limited" at frequencies above 20 Khz. I don't believe this to be "audible" to oider guys like me(in my 60's). Even if they were "audible" to very young ears, it 's probably only with a few recordings or test signals under tightly controlled lisening test in a quite enviroment.

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Gerry- thanks, great information. I have some gift certificates for Guitar Center, so I could buy the amp cheap. I just don't want to end up with something that isn't as good as the Dynaco 416 I have now. Even if they were equal, I would probably switch just for the reliability and warranty. I am leaning towards the Crown at this point, unless someone can suggest a better alternative in the price range.

-Joel

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  • 3 weeks later...

I got the Crown XLS1000, and I am very happy with it. It seems cleaner than my Dynaco 416. I have a Nikko Betta II preamp now, and I like it pretty well, but now I am wondering about newer preamps. Anyone have any experience with modern preamps? What about the Emotiva USP-1?

Thanks.

-Joel

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I think you'll notice a big improvement with a modern preamp.

There are a number of AR-9 owners who still like to power their restored speakers with vintage gear, and that's just fine, but the 9 will continue to show improvement with modern equipment.

Your new Crown amp is a good start, and the Emotiva pre has both phono & line-level inputs for a very low list price - the combination would probably make you forget your old Dyna & Nikko gear. :)

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I was looking at the Emotiva USP-1 because there was a used one on CL, but it is gone now. Buying it new is a little out of my budget. Any opinions on the Emotiva XDA-1 DAC? Except for the lack of a turntable, could this be used as a preamp? It is on sale now for $199.

-Joel

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I was looking at the Emotiva USP-1 because there was a used one on CL, but it is gone now. Buying it new is a little out of my budget. Any opinions on the Emotiva XDA-1 DAC? Except for the lack of a turntable, could this be used as a preamp? It is on sale now for $199.

-Joel

Hi Joel,

The Emotiva XDA-1 can be used as a preamp for digital sources. If you have any analog sources you'll need an analog preamp.

I keep looking at the Emotiva XDA-1 myself to replace the my Musical Fidelity V Dac. But from what I've read the V-dac is as good as any, so no sense for me to spend the money. Besdes I'm saving for another set of LST's if they become available. :rolleyes:

John

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  • 2 weeks later...

I had CROWN XLS2500s powering mine, bi-amped, for a while sounded pretty good - no complaints - very poweful - Then I switched over from a pro setup to Yamaha RX797 to drive the top and a Rotel RB-1572 for the woofers - sounds amazing.

re-applied the XLS2500s to bi-am a pair of CV CL215s - for a plain old loud stereo....

love my AR-9s though - best speaker I've heard, I like them so much I got 2 pairs!

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I think you'll notice a big improvement with a modern preamp.

There are a number of AR-9 owners who still like to power their restored speakers with vintage gear, and that's just fine, but the 9 will continue to show improvement with modern equipment.

Your new Crown amp is a good start, and the Emotiva pre has both phono & line-level inputs for a very low list price - the combination would probably make you forget your old Dyna & Nikko gear. :)

The only pre-amp I've ever owned was the Dynaco PAT 5; purchased around the same time I got my first power amp; a Dynaco 400. Both were purchased in kit form. As an "upgrade" from a receiver, it's a "good value". The "souped up" 416 was a modest - cost "upgrade" sufficient to drive most speakers of that era to its limits. But driving AR3a's or AR 9's, it’s NOT in the same league as the "vintage" Crown/ Adcom / NAD/ Macintosh designs.

As for pre-amps, the best "vintage" pre-amp I've used consistently (but never owned) was the APT- Holman Preamp. I did final quality control of those pre-amps before they left the factory.This pre-amp was considered the best "lab-grade" pre-amp in it's prime. While at BA, it was the reference pre-amp of choice for my lab, and in demo rooms used by sales and marketing for a very long time. In the Boston area, many still consider it as the best ever.

If there is one "flaw" with this unit, it is the relays. The contacts eventually wear out and operation becomes intermittent. Other than that, it is essentially a "straight wire with gain". The published and measured specs are impeccable. The precision and versatility of this unit is mind-blowing. If you happen to get one, be sure that you can find an expert technician to service it. In the Boston Area, a former APT employee named Mark Chamness once specialized in repairing APT and DBX stuff of that era. IMO, most knowledgle repair person for Apt products in the business.

I don’t know if there are any "better" pre-amps out there today. If there is, it’s probably "all digital" and very expensive. Probably less "industrial looking" as well. But I’d be VERY surprised if any of today’s units measure or "sound better" in a blind A-B comparison.

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For getting the best possible bass at high playback levels, I certainly believe so . I've never owned a "modern'"amp which uses these highly efficient "switching(?)power supplies. Such designs make it possible to have huge power at low cost . I don't know how they sound @ the mid - treble frequencies though.

I believe very early "classs H" designs had either very high distortion or limited power at the upper frequency spectrum. Today's "better" designs probably don't suffer from this. I believe the majority of today's "powered subwoofers" employ this technology. If there ARE "audible" midrange to treble distortion components, you certainly won't hear them thru the subs.

I THINK ( someone correct me if I'm wrong) from a "measurement standpoint" using test equipment, these efficient designs may be "band-limited" at frequencies above 20 Khz. I don't believe this to be "audible" to oider guys like me(in my 60's). Even if they were "audible" to very young ears, it 's probably only with a few recordings or test signals under tightly controlled lisening test in a quite enviroment.

Gerry,

I believe that many of the early class-D amps—a good example might be some of the Infinity Systems Class D amps used with their Servo Static loudspeakers—had severe issues with noise, buzzing, coloration and distortion at high frequencies. I've heard that much of this problem was due to the Class D's early design output filter performance and the filter's roll-off damping, resulting in earlier designs struggling with load-dependent high-frequency response, particularly at 20 kHz and above, as you noted.

This type of performance would be unacceptable in today's world, so major advances in error correction to reduce distortion has come about with the newer designs from the professional sound field. Current Class D and Class H designs from QSC and Crown have extremely low distortion and high-output power across the audio band. Noise figures are usually better than even the best consumer designs; of course, these amplifiers are robust and bullet-proof powering a variety of low-Z and low efficiency loudspeakers.

I have a new Crown XLS1000 (Switching Class D 300 watts/ch into 4 ohms) and an older class A/B XLS202 I use for testing(also 300 watts/ch into 4 ohms) as well as three QSC amps; a RMX-2450 (class A/B 650 watts/ch into 4 ohms), a GX3 (Class D 300 watts/ch into 4 ohms) and finally a PLX-3602 (Class H 1100 watts/ch into 4 ohms, 20-20k 0.05% distortion). Each of these amps is excellent in its own way, and each amp has no "sound of it own." The new Crown has the advantage of having a fan that does not run continuously, whereas the other amps have continuously running, but variable-speed fans. Incidentally, there is no difference in sound between the Crown XLS 1000 and the QSC GX3—both sound identical, which is exactly what you would expect.

Most importantly, each of these new designs has major built-in protection against overload, clipping and other issues. There is virtually no speaker load that can cause problems for these designs, and most of them will drive 2 ohm loads to very high short-term power. The big PLX 3602 amp can loaf along at a whisper or drive to very high levels, without strain. The SNL figures are -107 dB for this amp, which is good by any standard. One warning: driving the PLX 3602 at full output sine-wave power, 2 ohms, both channels driven, would draw 63 amps from the AC main power input, but of course no receptacle will furnish such power, and no speaker could sustain such power. The amp is rated to do this, but there would never be a need to run full power sine waves at such low impedances. Basically, this amp is never strained under any consumer-sound requirement. I've used it to drive stacked AR-LSTs and even stacked AR-3s (a very low-impedance load), the ADS L1590 and so forth, and it never seems to falter in any way.

In short, I've owned many excellent consumer amps over the years but no consumer amp was more effortless or reliable in my view than the new crop of Class D and Class H professional amps from Crown and QSC.

--Tom Tyson

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