Crown D-45 is excellent ss

[Duke Spinner]

Power Amp.................

[Marvel]

And QSC are primarily class H...

I see they say they are Class H, but I thought they primarily use a

switching PS, to gain efficiency, low weight, lower heat, etc.

Bruce

[Schurkey]

What about the Aragon Palladium series amps? Rated for 100/125

wpc into 8 ohms, CLASS A. But they will happily drive 400 wpc

into 8 in class AB mode, or 600 wpc AB into 4 ohms.

My understanding is that most any "Class A" style amp goes into AB mode if driven hard enough.

I think the Aragon 4004 and 8008 are listed as "class A/AB", that is

they are class A until a certain power level is reached, then they go

to AB. This level is much lower than the Palladium listed

above. I think the 8008 will drive 20-25 wpc in class A, but 200

AB all into 8 ohms. The 4004 will maybe drive 10-15 wpc Class A,

200 AB into 8 ohms, and runs cooler than the 8008 series, too.

[edwinr]

That'll teach ya, Duke. You need to keep your mouth shut!

[dragonfyr]

What is an amplifier?
by Steve Lyle

An amplifier is a device for making a larger, more powerful signal out of a small, weak signal.

It was on February 18, 1908 that Lee DeForest was granted U.S. Patent No. 879,532 titled "space telegraphy," but in actuality, the patent was for a vacuum tube triode amplifier that DeForest called the audion amplifier. For the first time it was possible to amplify signals.

The first amps were developed to support radio. Later, other applications were developed. All electronics depend in some way on amplification. Our industry uses Amps for audio.

An amp consists of two basic elements:
* A power supply that supplies a large energy source and
* An amplifier section that modulates the large energy source in accordance with the small signal

The result is a large, powerful signal.

CLASSES OF AMPS
Class A: A small signal modulates a larger current. This larger current is present when the small signal is not present. Efficiency up to about 26 percent. Excellent quality sound.

Class B: Uses a push-pull arrangement where one amplification device operates on the positive side of the waveform and another operates on the negative side. Efficiency up to 75%. Sounds bad because of distortion caused by switching from one device to another.

Class C: A small signal turns a larger signal on or off. There is no in-between state. Efficiency up to 90 percent. Not usable for audio. Audio requires accurate reproduction of all levelsnot just no power and full power levels.

Class D: A variation of Class C. Class D is a way of modulating a Class C amplifier to allow it to carry audio information. Sounds very good with latest technology. Efficiency up to 90 percent. Produces Electromagnetic Interference (EMI)

Class AB: A variation of Class B. Always has a small current flowing (class A operating region) and this eliminates the switching distortion inherent in Class B. Efficiency up to 65 percent. Sounds excellentif well-designed

Class H: A variation of Class AB. Changes the power supply voltage to the amplifier depending on the signal level. Improved dynamic efficiency. Requires complex power supply. Single tone efficiency up to 65 percent Sounds excellentif well-designed

POWER SUPPLIES
Type 1: Standard (Analog) Power Supply: Efficiency to 80 percent. Heavy, for large amounts of power. Components are large

Type 2: Switching Power Supplies: Efficiency to 90 percent. Lightweighteven for large amounts of power. Components are small. Can support universal line input voltages. Can support regulated output w/no power loss. Produces EMI

Efficiency is the power output of a device divided by the power input to the device. Power input that is not outputted by a system is dissipated as heat from the system. The greater the efficiency of an amplifier, the less AC power is required to deliver the same output power to the load.

A typical Class AB amplifier with a 65 percent efficiency, used with a standard analog power supply running at about 80 percent efficiency yields an overall amplifier efficiency of approximately 50 percent. Efficiency is typically rated at full power, continuous tone levels.

At lower power levels, efficiency is much worse. It is at low signal levels where Class D and Class H designs offer significant improvements. Class D maintains almost the same efficiency for all power levels while Class H switches to a lower power supply at lower signal levels in order to maintain good efficiency.

SWITCHING SUPPLIES
A switching supply consists of four basic building blocks:

1) A DC supply that operates directly off the AC line

2) A power oscillator which converts the DC supply to a very high frequency, typically 50 kHz200 kH

3) A transformer that changes the high frequency power signal to the various outputs needed

4) Rectification and filtering stages that produce the DC outputs needed

SMALLER & LIGHTER
Because the transformer in a switching supply is operating off a very high frequency power signalinstead of 50/60 Hzit can be much smaller and lighter.

This is the major advantage of a switching supply. Since switching supplies are more complex than a standard supply, their circuitry usually costs more. In addition, more parts have to be added to control the EMI produced by switchers.

But these costs are usually more than compensated for by the reduction in size, weight (and cost) of the transformer. In addition, costs of the chassis can be reduced because the weight it has to support is much less. Since the power supply is the heaviest part of an Amp, the entire product is much lighter and easier to handle.

AMP DESIGN TRENDS
For many years, the standard amp was a Class AB design with a standard analog power supply. Manufacturers have been experimenting with other types of both amplifier design and power supply design in order to support customer needs better.

The primary customer needs today for amps are:
- High Power
- Good Sound
- Low Cost
- Lightweight Construction

Good sound is very controversial. There is so much confusion about technical terms for rating good soundand how these terms actually relate to the listening experiencethat the focus today for most consumers is power rating and cost.

POWER RATINGS
Twenty years ago the rated output power of an amp was the continuous tone output level of the amp; a 300 W amp could produce a 300 W tone all day long. Then it was recognized that most audio Amps are not used on continuous tones, but are used on audio signals.

Audio signals consist of many tones of different power levels. So customers didn't need an amp that produced continuous tones all day; they needed an amp that could produce audio signals all day. This is easier and cheaper to do. Manufacturers today have adopted various methods for rating the power output of their products. This is causing much customer confusion.

Manufacturers, industry and standards groups have contributed to defining how to rate power output for audio Amps. There have been many methods proposed for rating amplifier power. Many of these proposalssuch as tone bursts testsattempt to rate the instantaneous or short duration power levels.

Because audio signals vary in duration and level, the validity of these rating methods depends on how the Amp is used and the characteristics of the signals it is amplifying. Some methods use non-audio signals, such as square waves, to determine the amplifier power rating; this causes the number to be higher.

Today, the primary standards are dictated by the Federal Trade Commission (FTC). Many manufacturers also use standards developed by Industry associationssuch as the Electronics Industry Association (EIA). Some manufacturers use other methods.

Safety agencies (particularly those in the European Union, and Underwriters Laboratories here in the US) have developed standards for measuring average continuous power of an amplifier. These are used in turn to measure maximum AC line power consumption and to confirm maximum temperatures. Safety groups have determined that typical worst-case power for an amplifier amplifying an audio signal occurs at one-eighth of the non-clipped output power (measured with a 1 kHz tone).

The amp is then cooked with a bandwidth-limited (20-20 kHz) pink noise signal whose power is equal to 1/8 of the tone full power. Measurements are then made for temperature and AC line power consumption. Thus 1/8 of the maximum tone power before clipping represents realistic worst-case continuous power levels for an audio amplifier.

Standards bodies are always reviewing and updating industry standards. We can expect standards for audio amplifier testing and ratings to change as our customers' needs and usage changeand as our knowledge and technology improves.
http://www.prosoundweb.com/install/tfw/amps.php

[edwinr]

Nice post, dragonfyr.

[Marvel]

Thanks. Thant is a bit clearer than some of the other explanations I have seen.

Dean likes his QSC, but then he likes Mudvayne as well. []

Bruce

[leok]

Julie,

The Crown has 2 volume controls (one for each channel). It may be used

with a line input (cd player, tuner, etc. but not phono cartridge)

directly, but volume adjustment will be inconvenient. It develops full

power with only about 0.75V in so preamplification is not necessary. I

use a remote volume control ("passive preamp") and have the Crown

volume controls adjusted so the passive uses its full range. One thing

people might keep in mind is the input impedance, single ended, is

10KOhms. This may be an issue with tube line stages. SS sources

generally have no trouble with this.

Leo

[rigma]

Leo,

I sent you a PM.

rigma

[Duke Spinner]

important point, LeoK .............

a lot of complaints of " i dont understand how you can say

equipment XXX is so good ... it sounds like crapola in my system"

is really due to Impedance Miss-Match

by the way, LeoK .......look what you've started here ......[]

[JulieHeartKlipsch]

Thank you Leo. What remote volume control do you use? Does it

have to be special for to work properly with the Crown type amplifier?

[leok]

JulieHeartKlipsch,

I use a Creek OBH-12 which uses 50KOhm audio taper pots. I recommend

50KOhm for the Crown because it is a somewhat stiff load at 10KOhms

(nothing to worry about, but something to take into consideration). I

don't think Creek still offers the OBH-12, but there might be a

replacement at audioadvisor.com. There are plenty of products and DIY

designs out there.

Duke: You've brought valuable information to this site. Your knowlege

concerning the Crown lineup was the basis of my decision to try the D

series. I know you know that, but others may not.

Leo

[Speedball]

When I think of a Crown K2.....I think of Dukes Avatar.....

Maybe Santa will be nice enough to bring me one for Christmas.

[codhead]

My eBay D-45 arrived today. It's brand new! Just one small problem... there was some adhesive residue on the back panel - where the serial number used to be. This one must have fallen off the truck. Oh well, guess I can't ***** too much for 180 bucks.

Absolutely stunning sound. Smooth, balanced, and plenty of tight,

controlled bottom end. If this is any indication, SS has come a long

way since my mid 80's gear.

I have to admit, I was pretty skeptical after my experience with that dreadful (IMHO) little Teac.

I was curious about what it would take to trigger the IOC (clipping)

indicators. Those Cornwalls sure put out a whole lot of volume before

the red lights start to flicker.

Kind of hate to admit this, but the D-45 seems to be a better match

with my Corns than my SET amps. With SET, the Cornwall squawkers seem

to run a lot hotter. I don't notice this with the Chorus, but I sure do

with the Corns. This has been a major source of irritation ever since I

got the Cornwalls up and running. Not so much a problem on good

recordings, but the hot mids make bass deficient recordings sound

really bad. For some reason, these same recordings sound a whole lot

better with the D-45.

Guess I need to hook up my Dynaco, and see how it sounds on the Corns.

Wonder if this is an impedance issue, as the Chorus uses a more modern

crossover design? Right now, I'd give the nod to the Chorus as being a

better sounding speaker with SET gear.

At any rate, I'm very happy with the D-45. It's a fine sounding, well

constructed little amp. If any of you have been sitting on the fence, I

don't think this is a purchase you would regret.

[sputnik]

After reading this, I'm thinking I might try one for myself. Cost aside, would

there be any advantage to bridging two D-45s over a single D-75?

[colterphoto1]

I've got an old BGW 75, is it in the same league at all with the Crown?

Michael

[JSharp]

My eBay D-45 arrived today. It's brand new! Just

one small problem... there was some adhesive residue on the back panel - where the serial number used to be. This one must have fallen off the truck. Oh well, guess I can't ***** too much for 180 bucks.

Absolutely stunning sound. Smooth, balanced, and plenty of tight,

controlled bottom end. If this is any indication, SS has come a long

way since my mid 80's gear.

I have to admit, I was pretty skeptical after my experience with that dreadful (IMHO) little Teac.

I was curious about what it would take to trigger the IOC (clipping)

indicators. Those Cornwalls sure put out a whole lot of volume before

the red lights start to flicker.

Kind of hate to admit this, but the D-45 seems to be a better match

with my Corns than my SET amps. With SET, the Cornwall squawkers seem

to run a lot hotter. I don't notice this with the Chorus, but I sure do

with the Corns. This has been a major source of irritation ever since I

got the Cornwalls up and running. Not so much a problem on good

recordings, but the hot mids make bass deficient recordings sound

really bad. For some reason, these same recordings sound a whole lot

better with the D-45.

Guess I need to hook up my Dynaco, and see how it sounds on the Corns.

Wonder if this is an impedance issue, as the Chorus uses a more modern

crossover design? Right now, I'd give the nod to the Chorus as being a

better sounding speaker with SET gear.

At any rate, I'm very happy with the D-45. It's a fine sounding, well

constructed little amp. If any of you have been sitting on the fence, I

don't think this is a purchase you would regret.

Cod -

From the Crown manual -

The IOC (Input/Output Comparator)

indicators work like sensitive distortion

meters and flash when the amplifier causes any

distortion of 0.05% or more. The IOC indicators

typically glow for about one minute after

the AC power is turned off.

You can download a copy of the manual here - http://www.crownaudio.com/pdf/amps/125243.pdf

By the time the IOC lamps start to flicker with my Cornwalls and D-75A, stuff is falling off shelves in the kitchen...

[]

They are really nice amps. When you consider what they cost, they're great amps IMO.

[sfogg]

" The IOC (Input/Output Comparator) indicators work like sensitive distortion meters and flash when the amplifier causes any distortion of 0.05% or more. "

Worth pointing out that even when those light up the amp isn't clipping yet. Just that distortion has risen above the 0.05% point. I think Crown says those light up about 10x earlier then clipping lights would... at least they do on other amps of theirs that have both IOC and Clipping indicators.

Shawn

[Parrot]

My eBay D-45 arrived today. It's brand new! Just

one small problem... there was some adhesive residue on the back panel - where the serial number used to be. This one must have fallen off the truck. Oh well, guess I can't ***** too much for 180 bucks.

Hey! that sounds like it might be my amp! Is it black?

[codhead]

"Hey! that sounds like it might be my amp! Is it black?"

LOL... yeah, sure is. You missing a bunch of flat panel TV's too?