Resurrecting a Crown DC300A
Scroll to post #78. It has the best copy of the DC300 schematic of all time!
One of the guys I know who works in Pro Audio does not have very nice things to say about post-2000 Crown amps, either for sound quality or build quality. Something about having some of the newer Crown amps failing on a monthly basis in an installation.
Unfortunately, a lot of times when great companies get bought by conglomerates, they end up dying a slow and painful death.
I 'love' Behringer amplifier specs that are clearly not defined by industry standards. Like their amps that deliver 4000 watts from an AC line source limited to 1800watts/15 amperes/120 volts in North America in the electrical code. I am not a big fan of that BS marketing that wins the minds of the uneducated. It boils my blood and makes me happy I grew up when such notation & claims were more or less on the level.
Actually, everybody does that now. Line current is now rated at what the amp draws when putting out 1/8 power with pink noise. This DOES make the amp clip, and it will put out more power and draw more line current with a sine wave. Back in the DC300A days, line current was rated for a full signal sine wave. But when amps started getting too big you couldn’t legitimately run one off a standard plug the way they were rated. but in most applications you could. So they re-thought the standard.
Trouble is that makers like Berhringer took it a little too far. They do inflate their power figures, regardless of how they are rated. What’s worse, is that the “6000 watt” I-nuke will really put out about 1800 watts per channel for repetitive bursts. But you do that every knight playing ghetto bass and it won’t last very long. Modern Crown equipment won’t last a lot longer, but longer nevertheless. A lot of the old iron horses are still on the road, and still more would be if it weren’t for the weight.
Trouble is that makers like Berhringer took it a little too far. They do inflate their power figures, regardless of how they are rated. What’s worse, is that the “6000 watt” I-nuke will really put out about 1800 watts per channel for repetitive bursts. But you do that every knight playing ghetto bass and it won’t last very long. Modern Crown equipment won’t last a lot longer, but longer nevertheless. A lot of the old iron horses are still on the road, and still more would be if it weren’t for the weight.
What parameters justify such a 'BIG' statement? To take a decade of good, bad & ugly and tie them up into a single ribbon of: "pinnacle of audio power amplifier design" ?
You, H713 are clearly off you rocker! Ha ha I love it.
He means that by the 90’s class AB solid state amplifier technology, and the semiconductors that support it, had fully matured. And it was all downhill from there, driven by mergers and bean counters trying to shave nickels off of everything.
To quote a famous fictional miser, “Now do I paint an accurate picture, or do I exaggerate?”
To quote a famous fictional miser, “Now do I paint an accurate picture, or do I exaggerate?”
I should have noted that I meant linear amplifiers- not including class D.
From my perspective, the best amps that have been made are 1990s amplifiers. By the 90s, engineers had pretty much mastered the challenge / art of designing a good-sounding Class AB audio amplifier with decent reliability. They were, for the most part, more refined, and considerably more reliable than what came in the decades before. Yes there were exceptions, but especially in the pro audio segment, the 1990s amps were engineering masterpieces. Amps like the MC series from MC2 and the EPC series from BSS were sophisticated and well-executed designs, in many ways a refinement of what came before them.
By the 2000s, between the cost-cutting, the acquisition of a lot of companies and the rising popularity of class D amplifiers, a lot of the great amps of the 1990s were no longer profitable to sell. Added to that, the demand for good amps declined with more and more people choosing iPods, earbuds and cheap bluetooth speakers over a high-performance stereo. The pro market wants whatever is lightest and most efficient, not necessarily what sounds the best. There are still good amps being produced today, but not in the quantities that were made back in the 90s.
This is all my (highly subjective) opinion. I've never been particularly enamored with the old Marantz or Sansui receivers. I don't have much against Class D, other than that I find it boring.
From my perspective, the best amps that have been made are 1990s amplifiers. By the 90s, engineers had pretty much mastered the challenge / art of designing a good-sounding Class AB audio amplifier with decent reliability. They were, for the most part, more refined, and considerably more reliable than what came in the decades before. Yes there were exceptions, but especially in the pro audio segment, the 1990s amps were engineering masterpieces. Amps like the MC series from MC2 and the EPC series from BSS were sophisticated and well-executed designs, in many ways a refinement of what came before them.
By the 2000s, between the cost-cutting, the acquisition of a lot of companies and the rising popularity of class D amplifiers, a lot of the great amps of the 1990s were no longer profitable to sell. Added to that, the demand for good amps declined with more and more people choosing iPods, earbuds and cheap bluetooth speakers over a high-performance stereo. The pro market wants whatever is lightest and most efficient, not necessarily what sounds the best. There are still good amps being produced today, but not in the quantities that were made back in the 90s.
This is all my (highly subjective) opinion. I've never been particularly enamored with the old Marantz or Sansui receivers. I don't have much against Class D, other than that I find it boring.
I knew that "6000 W" amps sold without installation by an electrician who does 440 vac 3 phase, was snake oil. Post 25 explains the mystery. I won't be buying any six kilowatt amps that actually put out 1.3 K. I have a nineties PV-1.3K, suitable for playing outdoor crowds of 300 if they leave their Harleys shut off. The city blocks the street near our Warder park during free concerts to keep the V-twin motos away.
I recently refurbed what I believe is a 90's amp - an Altec-Lansing 9444a and what a great amp. Can't say enough about its quality and great sound. Key was replacing the NE5532 in the input stage with an OPA1642, at the suggestion of a couple of guys on the Altec-Lansing group.
For some types amplifiers with op-amp input stages, I like the LF353 better than the 5532. Much better SQ. But the 353’s load driving ability is about nil, so it can’t be used where it drives the output stage directly (most QSC). It does however work in most other amps with op amp front ends, except for the BGWs which require a decompensated op amp (318). It might work, but I’ve never had to try. I have with the Crowns. The reason those two are so often used is because they will not fry from startup and clipping transients. Ive tried many different “better” op amps and ended up with fried op amps the instant the amp clips and sometimes on startup. All of my DC300A clones and my CS800 clone use the 353. As well as all my newer much more high power PA stuff. Some new development efforts use the 5532 in the rest of the input circuitry (balanced input, limiter, filter, bridging circuit), but I’m re-thinking that because of the TI distortion. I do have some old Signetics, but they will eventually be used up.
What's SQ?
For the cs800x & cs800s Peavey used NJM4560 for input & driver op amps. It is nice and quiet with no signal. Since the input opamp is socketed I tried swapping for ST33078 which newark lists as "low noise", but I couldn't hear any difference so I put the 4560 back. Peavey has "DDT" to detect and suppress clipping. Running the CS800s 14 hours a day now, no problems since the caps in the switcher power supply were replaced (and blown .160 A fuse).
As input op amp Peavey went through 741 to 4558 to 4560 in their 5 or more revisions of the cs800. Never used 5532 for some reason. At gain 50 in my MM RIAA mixer, I found 4558 hissy, changed to 33078 which is much better. But 33078 needed additional bypass & feedback caps to not oscillate.
MC2 also used the 5532 in the MC series. Not heard to many people who dislike that particular amplifier series, aside from the weight and the cost.
The 5532 gets plenty of hate, but I've never had much reason to dislike them. They perform quite well. Low noise and distortion when used correctly.
Now the 741... that's a whole other level of crumminess. Isn't the slew rate on a 741 something pathetic like 0.7 V/uS?
Edit: The slew rate is even worse at 0.5 V/uS.
The 5532 gets plenty of hate, but I've never had much reason to dislike them. They perform quite well. Low noise and distortion when used correctly.
Now the 741... that's a whole other level of crumminess. Isn't the slew rate on a 741 something pathetic like 0.7 V/uS?
Edit: The slew rate is even worse at 0.5 V/uS.
I found the 5532 to be rather hard sounding in the Altec-Lansing, compared to the OPA 1642 and another op amp I tried. Perhaps it was the application. I have the classic 47 headphone amp with a couple of 5532's and it sounds fine.
Yeah, but Peavey used the 741 about 1976. Cutting edge technology in 1976. They have never had a presence in the hifi market, that would mess up their southern rock image. But with .03% hd and 40 v/usec slew rate in the cs800s, they are close enough to hifi for me, at a used price of $100. Look at the price of a blown up parasound or NAD, by contrast.
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Crown has a whole set of documents available on-line and for free. Be sure to search for the DC300AII and not just DC300.
Crown Audio - Professional Power Amplifiers
https://www.crownaudio.com/en/site_elements/dc-300aii-service-manual
Crown Audio - Professional Power Amplifiers
https://www.crownaudio.com/en/site_elements/dc-300aii-service-manual