colterphoto1 Posted September 20, 2005 Share Posted September 20, 2005 Well, suffice to say that Roy Delgado, Chief Engineer at Klipsch, Hope Arkansas has a couple of them in his listening room for testing and voicing new speakers. That should say volumes. They are the black faced newer model 300's (?). Saw them myself. Also had a rack of 4 (four) QSC amps for a/b/c/d comparison testing. Not a tube in sight. Michael Quote Link to comment Share on other sites More sharing options...
djk Posted September 20, 2005 Share Posted September 20, 2005 "by the way .... most Crown amps.... are class A / A+B" If you look at the schematics they list the bias voltages. Most Crown amps run the outputs class B, with only 340mV of base voltage. It takes 650mV to get the outputs into conduction at all. Quote Link to comment Share on other sites More sharing options...
dragonfyr Posted September 20, 2005 Share Posted September 20, 2005 The D Series runs AB+B. Other high end series are primarily A/AB.The D-45 and D-75A amplifiers are compact and provide ultra-low distortion for medium power applications. Crowns advanced AB+B circuitry ensures efficient operation and protects against shorted, open, mismatched or low-impedance loads that can affect any amplifiers performance.Output topology employs Class AB+B mode of operation where the driver transistors carry the bias current while the output transistors serve only as boosters. The output transistors sense when the driver transistors are developing significant current draw from the load and thus take over and deliver the needed current. The output stage is of a quasi-complementary format using no bias current into the output transistors themselves.The result is maximum efficency with minimum crossover notch distortion and idling amplifier heat. Protective circuitry includes Voltage-Current limiting, superior to most other forms of protection because it directly senses the overload condition and instantly reacts to relieve the overload, and acts only as long as the overload exists. Front panel indicators are provided to show signal presence and IOC (Input-Output Comparator), indicating distortion greater than 0.05%....from D series manual Quote Link to comment Share on other sites More sharing options...
leok Posted September 20, 2005 Author Share Posted September 20, 2005 Jeff, I didn't realize you were talking D-75. Take a good look at the specs. Crown doesn't make the same remarkable claims for low distortion at low power with the D-75 as they do for the D-45. I think they went all out to clean up the low end on the -45. That may just be the piece of the puzzle that makes this amp work for me. Leo Correction: I looked back at the specifications and don't see a difference either. Quote Link to comment Share on other sites More sharing options...
Painful Reality Posted September 20, 2005 Share Posted September 20, 2005 What spec sheet are you referring to? From what I was able to see, specs seemed to be the same for the D-45, D-75 and D-75A. Did I miss something? Quote Link to comment Share on other sites More sharing options...
codhead Posted September 20, 2005 Share Posted September 20, 2005 Just scored a mint D-45 with box/manual for $175 on eBay. Was gonna go for a new one, but for under 200 clams with shipping, I just could not resist. Someone at Crown has a great sense of humor. Check this out... http://www.crownaudio.com/pdf/amps/belchfire_datasheet.pdf Quote Link to comment Share on other sites More sharing options...
leok Posted September 20, 2005 Author Share Posted September 20, 2005 Jeff, I looked back and don't see a difference. Sorry for the misleading statements. Also, I corrected my earlier entry. Thanks for catching me on that. Leo Quote Link to comment Share on other sites More sharing options...
3dzapper Posted September 20, 2005 Share Posted September 20, 2005 CH, LMAO!!!!!!!!!!!! Rick Quote Link to comment Share on other sites More sharing options...
arfandbark Posted September 21, 2005 Share Posted September 21, 2005 I like the way my Crown PS400s' run my Cornwalls. Enough to buy another as a spare. But what do I know? WOOF! Quote Link to comment Share on other sites More sharing options...
colterphoto1 Posted September 21, 2005 Share Posted September 21, 2005 Thanks for the Belchfire piece. Very well written blurb sheet. Myself, I'll stick with my Microtech 1200. Got to get that dusted off and powering my JBL bins. I keep meaning to try out that combo as an intense sub system. But it does take up a lot of acreage in the living space. Michael Quote Link to comment Share on other sites More sharing options...
Myhamish Posted September 21, 2005 Share Posted September 21, 2005 ditto to all the above - good ole' USA made Crown is in there for the long haul - got one that's been around for 30 years (300A) that still perks up the dog's ears Hamish Quote Link to comment Share on other sites More sharing options...
JSharp Posted September 24, 2005 Share Posted September 24, 2005 ditto to all the above - good ole' USA made Crown is in there for the long haul - got one that's been around for 30 years (300A) that still perks up the dog's ears Hamish Crown is in it for the long haul and treats their customers well. It's always been this way. I just called them for a schematic on a 25 year old long out of production item. The guy in customer service copied the full sized schematics they had for two different revisions of the same model and sent them to me. I had them in two days. On the D45 - D75 subject. I scored a D-75A on eBay a few weeks back for $130. Decent condition, only the noisy input level controls needed a little attention. I just don't see how a person could go wrong with one of these units. Quote Link to comment Share on other sites More sharing options...
artto Posted September 24, 2005 Share Posted September 24, 2005 Good goin' Leo! Glad to see someone else has discovered these little gems! <?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" /> For most of my everyday needs Ive been using some Crown D-60s to power the Khorns for decades. No, they dont hold a candle to my Luxman triodes, but few amps of any kind, at any price do. I just leave the D-60s on 24/7. Ive had one them as the original owner since 1973. IMO, those old, little, low powered Crown amps are amongst the best sounding amps Crown ever made, and hold their own very well against amps costing 10-100x more. You can pickup one these on Ebay for $100. The D45, D60 and D75 are all very similar, all descendants of the Crown SA 20/20 (Crowns first amplifier) and SA30/30 (I also have a SA30/30). Quote Link to comment Share on other sites More sharing options...
artto Posted September 24, 2005 Share Posted September 24, 2005 by the way .... most Crown amps.... are class A / A+B the are class A biased at low power output Crown has a lot of very innovative output circuts, BCA for one ... the current unused by the speaker, is returned to the amp ... Sorry Duke, They are Class AB+B. And this particular configuration is now used by almost all amplifier/receiver manufacturers even though they don't say so. http://www.crownaudio.com/pdf/amps/grbgpapr.pdf Quote Link to comment Share on other sites More sharing options...
Duke Spinner Posted September 24, 2005 Share Posted September 24, 2005 the driver stages are Class A biased the D series amps, run class a up thru maybe 950 milliwatts, the sweet Horn operating range at low levels this from a crown service manual Quote Link to comment Share on other sites More sharing options...
dragonfyr Posted September 24, 2005 Share Posted September 24, 2005 And QSC are primarily class H... Quote Link to comment Share on other sites More sharing options...
artto Posted September 24, 2005 Share Posted September 24, 2005 the driver stages are Class A biased the D series amps, run class a up thru maybe 950 milliwatts, the sweet Horn operating range at ow levels this from a crowm service manual OK, I would like to see the manual or web link or some documentation. Sometimes what gets printed in the manuals or promotional propoganda is incorrect. I don't mean to start another argument, but "technically" speaking, there is no such thing as "Class A up to some point". By definition, a Class A amplifier must conduct 100% of the time, regardless of whether or not a signal is present, or what the amplitude of the signal is. The link I provided from Crown's website published in a "white paper" about the patented technology says Class AB+B, and I quote: The first device in the chain is called the predriver, and the second is the driver. Together these two devices are biased to operate Class AB. <?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" /> The last part of the Darlington is the output transistor device. The output device is biased so that it is off when no signal is applied, but requires only a small signal to begin conduction. Combining the AB stages with a Class B stage produces a net classification of AB+B. Quote Link to comment Share on other sites More sharing options...
Duke Spinner Posted September 24, 2005 Share Posted September 24, 2005 what's wrong with an argument ...??? I Enjoy that Art ..... think about it Artto .... at Milliwatts you are operating BELOW the switching threshold, at which point the output devices trigger perhaps ....you are only listening to the Drivers ... I'll ask Dave Glass at Crown i think thats where the info came from............................[] Quote Link to comment Share on other sites More sharing options...
artto Posted September 24, 2005 Share Posted September 24, 2005 Some more food for thought: What's one of the "technical" terms for a transistor? "Gate", correct? What's one of the technical terms for a vacuum tube? "Valve", right? A gate acts more like a "switch" and that's what transistors are good at, turning on and off. A vacuum tube on the other hand is called a valve. It's naturally better at controlling/regulating "flow". Music/waves don't turn on and off like a switch. A valve is much better suited to the application without the finagling that transistors must be to be "coaxed" into doing to produce the same thing. Another thought: Gerald Stanley (?) of Crown once said something to the effect "Given enough time, money and resources, virtually anyone can design a great sounding cost-no-object amplifier. The difficult part is designing an amplifier with all the cost-no-object attributes that can be manufactured at an reasonable price and maintains high reliability under all operating conditions". As one Crown engineer I spoke with put it, "We like to think of our amplifiers as being 'customer proof' " Quote Link to comment Share on other sites More sharing options...
JulieHeartKlipsch Posted September 24, 2005 Share Posted September 24, 2005 Is this an integrated amplifier, meaning it has a preamplifier built in or does it need a preamplifier also? Julie Quote Link to comment Share on other sites More sharing options...
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