Crown amps that is at least the Studio Reference series (and the presumably identical Macrotech / Macro Reference) do have a particular pronounced, live-like and realistic slam / punch in the bass. Having had or tested several class A, AB, Mosfet, non mosfet amps, valve SET or PP etc. etc. I must say this bass is really particular. A friend of mine has made the same observation and he uses/has used a variety of amps including big audiophile US amplifiers. We both use large enclosures with 15" woofers (JBL Everest, Onken W-inspired cabinet) mono-amplified and passive equalized.
Let's forget a minute about the figures, especially the abnormal high damping factor. The explanation probably lies elsewhere and I'd like to hear those points of view. I also remember a guy back in the 1980s (before SR and Macrotech even existed I guess) who worked for a PA rental business and who always stated that the Crown / Amcron slam was something special.
Is anyone familiar enough with the topology specifics of these amps and able to explain what their secret is, or formulate a hypothesis ?
Let's forget a minute about the figures, especially the abnormal high damping factor. The explanation probably lies elsewhere and I'd like to hear those points of view. I also remember a guy back in the 1980s (before SR and Macrotech even existed I guess) who worked for a PA rental business and who always stated that the Crown / Amcron slam was something special.
Is anyone familiar enough with the topology specifics of these amps and able to explain what their secret is, or formulate a hypothesis ?
The power does not come into play. Believe me. My loudspeaker system is much above 100 dB/1m/2,83V and the slam is there even at very reasonable levels (can't use much anyway except on classical and acoustical music recorded without compression).
Appearance: Hmmm. They don't look as provocative, excentric or "hi-endish" as many other amps. And at nearly 50, I need more to turn me on suggestively.
They're also heavy so they make a wicked slam when you drop them on your toes.
Good solid-state amps have very low levels of distortion. So low that it is really hard to find any explanation for the subjective differences in sound that many people report.
Come on man...I'm sure we can come up with better explanations / theories.
But the appearance suggests power. You are by definition unaware of your subconscious reactions and biases.
Seriously, it's all suggestion.
That's power, which elac has already dismissed.
Maybe but not that much. There is a relatively big toroid transformer, the supply runs at about 100V (P=U^2/R) but the main caps are ridiculously small on the capacitance side, by audiophile standards (2x6800uF if I remember).
It's a class AB design, but clearly leaning more towards B than A.
No it's mostly the fully-regulated power supplies. Of course they do it partly to make the amps portable and small (like you noted, the main caps and power transformer are relatively small). So it's not just the power they have, it's the fact that they have NO power compression and instant recovery (errr, nothing to recover from). I have 13 big amps that have completely different FET amplifier sections than Crown's bipolars, but similar compact power supplies that are fully regulated, and they also don't have any 'sag'...the sound is the opposite of a tube-rectified amp. The fully-regulated supplies really excel with dynamic range expanders. You think it's not the power? Well it's not just the momentary or even continuous power rating, it's that there's NO power compression, no audible recovery, no audible "breathing" of the power supply. Then the issue becomes whether your speaker voice coils can dissipate the heat or they will introduce compression (but longer to come on and longer to recover). The difference becomes more obvious with live perfomance, as all those Crown amps have been used for bass guitar and contrast against the tube-rectified guitar amps or guitar amps that let you switch between different rectifiers or introduce B supply resistors to sag on purpose, some intentionally want the power section draw to reduce the preamp voltage. A bass guitar can have extreme dynamic range, and some music and playing styles use compression, others want that dynamic range and punch (and a noise gate's downwward expanson makes it sound even punchier). Some electric instruments have so much dynamic range you can compress and limit and still have punch. The Crown VZ amps are famous for that punch without compression or recovery. At the opposite lower end of the cost line the Soundcraftsmen shoeboxes had some of that lack of compression due to their fully-regulated supplies.
And, much as we laugh at the tweek-heads who get big power cables, the sound, if any, of heavier power cables might be less sag and faster recovery, at least compared to undersized power cables.
My old Bose power amps had huge transformers and huge power caps, and stiff supply "regulation" characteristics, but the fully-regulated switching-mode supplies and fully regulated pulse-width-modulation supplies have no sag. At all. Which is why live sound and DJs love them (plus they're portable and tolerate crappy power and crappy power cords). Yet, the amplifiers are not switching-mode, so they do have power caps with some dynamic reserves and some overload characteristics (OK they have sag then, which you will probably rarely experience) whereas a 500-watt class "D" switching amp won't make 501 and needs a limiter or it sounds terrible if you overdrive it. A relatively conventional 500-watt amp with a modern fully-regulated supply will sound far better (punchier, less compression, more dynamic range) loud than a 500-watt amp with a conventional supply that's already sagging to wheeze out that continuous rating or than a 500-watt class "D" amp that you have to drive at one-tenth power to avoid disturbing noises on peak demands. It's not that these amps are that punchy, it's more that most amps turn down for a fraction of a second after each loud part.
And, much as we laugh at the tweek-heads who get big power cables, the sound, if any, of heavier power cables might be less sag and faster recovery, at least compared to undersized power cables.
My old Bose power amps had huge transformers and huge power caps, and stiff supply "regulation" characteristics, but the fully-regulated switching-mode supplies and fully regulated pulse-width-modulation supplies have no sag. At all. Which is why live sound and DJs love them (plus they're portable and tolerate crappy power and crappy power cords). Yet, the amplifiers are not switching-mode, so they do have power caps with some dynamic reserves and some overload characteristics (OK they have sag then, which you will probably rarely experience) whereas a 500-watt class "D" switching amp won't make 501 and needs a limiter or it sounds terrible if you overdrive it. A relatively conventional 500-watt amp with a modern fully-regulated supply will sound far better (punchier, less compression, more dynamic range) loud than a 500-watt amp with a conventional supply that's already sagging to wheeze out that continuous rating or than a 500-watt class "D" amp that you have to drive at one-tenth power to avoid disturbing noises on peak demands. It's not that these amps are that punchy, it's more that most amps turn down for a fraction of a second after each loud part.
Last edited:
Amplifiers like this sound good, even when the peaks are driven 6dB into clipping. You won't even notice it unless you're watching the IOC indicators. Comapre this to a switching amp that sounds like a mistuned FM radio station when driven slightly into clip, or your average home stereo which is somewhere in between.
The more average power you can get before it goes to hell in a handbasket, the more 'slam' you're going to get.
The more average power you can get before it goes to hell in a handbasket, the more 'slam' you're going to get.
That's an interesting explanation.
I tried to check the schematics to see if indeed these amps have regulated power supplies - http://www.crownaudio.com/media/pdf/legacy/StudioRefScrvsManual.pdf but I can't find these in the service manual. The Manual seems to speak of regulated PS only for the input stage and protection circuitry.
Bearing in mind that the caps can store about 10A and quite some joules (guessing by their side) I imagine that the benefits of a fully regulated PS in the way you mention (PS not saging on power demands) would be particulalry obvious at high levels of use. Maybe I should have pointed out that I use this equipement in home audio. I really just use a fraction of the amp's nominal power. Would the benefits of the regulated PS be so obvious also at fairly low levels of say 0,25-5W ?
By the way, I also built some years ago a 15W class AB amp, with a 40A toroid and 2 banks of 10 caps (20 caps) for a total of 200,000 uF (each cap taking about 8 A), not regulated. When the power switch was turned off, the amp would still play for a few seconds at reasonably high level.
My guess is that this power supply was not prone to sag (they way I understand this phenomenon), but still, bass expression was average (read: as good as most high end amps around), without real kick or slam.
My guess is that this power supply was not prone to sag (they way I understand this phenomenon), but still, bass expression was average (read: as good as most high end amps around), without real kick or slam.
- Status
- Not open for further replies.