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Crown D-150A Series II
80 WPC Stereo DC Amplifier
(1986-1991)
Made in USA

© 2015 KenRockwell.com. All rights reserved.

Intro   Specifications   Measurements

Sound   Usage   Recommendations   More

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Crown D-150A Series II

Crown D-150A Series II (3 RU, 19" rack mount, 8" mounting depth, rated 80 watts per channel, 24 lbs./10.9 kg, measured 38 watts idle power draw, about $150 used) in optional walnut veneer cabinet. The cabinet is uncommon and sells for about $160 if you can find one. enlarge. I got these at this link directly to them at eBay (see How to Win at eBay).

This ad-free website's biggest source of support is when you use those or any of these links to approved sources when you get anything, regardless of the country in which you live. Buy only from the approved sources I use myself for the best prices, service, return policies and selection. Thanks for helping me help you! Ken.

 

Crown D-150A Series II, rear

Rear, unmounted Crown D-150A Series II. enlarge.

 

June 2015       Crown reviews    audio reviews    all reviews

 

Introduction         top

Intro   Specifications   Measurements

Sound   Usage   Recommendations   More

IOC   Proof-of-Performance    History

Adorama pays top dollar for your used gear.

B&H Photo - Video - Pro Audio

The Crown D-150A Series II is an extremely high quality professional stereophonic power amplifier. It's rated at 80 watts per channel (WPC), and like all American amplifiers, puts out much more than that.

This amplifier sold for the equivalent $1,500 when new; this is a first-class professional product built to last a lifetime.

The Crown D-150A Series II is the grandson of the 75 WPC Crown D 150 of 1971, which was rated at 75 watts per channel. 75 times two equals 150, its model number. It was introduced as a sane version of the beastly DC-300, but still with more than enough power for home Hi-Fi and studio monitoring use at an even more reasonable price, still with all the performance of the DC-300.

This is a bulletproof amplifier built to tough commercial, not consumer, standards. It has solid metal knobs, glass-epoxy circuit boards and a three-year no-fault warranty — with Crown paying the shipping if it fails. Crown proclaims in the manual that it "should provide you with a lifetime of trouble-free service." I haven't tried, but I certainly believe it would take quite a few rounds from a 22-calibre rifle before it had any problems.

As a testament to its tenure in major studios, you'll see it has a certification label for the City of Los Angeles' electrical code. If you've ever built a studio in Hollywood, you'll sometimes have the inspector show up and expect everything to have this sticker on it. In this case, Crown has already gotten this approved to save you the hassles of dickering with inspectors.

These don't break, which is why they have been so popular with touring rock bands as well as in recording studios. That also means that most of them you see today will have come off a long tour on the road, and are well worn to prove it.

One of the subtle things that show how far Crown has gone to make this amplifier survive abuse is how little free space there is behind the front knobs. If you bang this amplifier into something, the knob won't be able to be pushed in far enough to damage its potentiometer; it may scrape the front panel but not bash-in the control behind it.

Stress-testing this old sample at beyond clipping at 100 WPC steady-state at 3% THD for an hour with the IOC distortion indicators lit the whole time, it fried and burnt my test loads. My test loads got so hot they actually dripped solder and burnt my bench, but my D150A Series Two wasn't much warmer than usual and was completely unaffected.

The D150A II has the perfect combination of size and power for home Hi-Fi use. It sells for pennies on the dollar today because the market is flooded with them. Touring bands are opting for lighter-weight class-D amplifiers to give them less to carry, and recording studios use active monitors with amplifiers built into the speakers. Thus as these come off tour or out of the studio, eBay is loaded with them.

The D 150s are real class A+AB amplifiers and sound much better for Hi-Fi than the newer class-D garbage used on tour. These linear Crown amplifiers are also designed for efficiency so they don't get hot. They need no fan. They cool themselves through convection, radiation and conduction through their all-aluminum chassis — and have much less noise, distortion and flatter response than newer professional amplifiers.

They will get not more than mildly warm after many, many hours, even sitting in a wood case as shown above. If you only use it for an hour at a time, it won't even get warm; it takes many hours to reach final operating temperature.

It plays immediately when turned on. There's a big power surge drawn from the wall since there are no inrush protectors, but it does play immediately with no thumps.

If you have no signal, it turns off silently. If you still have signal applied, it plays for several seconds with distortion, and then the distortion goes away and it plays for several more seconds softly as it fades out, maybe with a little bit of hiss after about 10 seconds without power.

Odd for a professional amplifier, the D-150A Series II uses unbalanced ¼" jacks for inputs. These are not professional balanced inputs; they are simply tougher connectors than RCA jacks. Use two ¼" to RCA adapters and you're set.

This is a true DC amplifier. Bass nuts take note: it really does amplify straight down to direct current with perfectly flat frequency response and zero phase shift. Even the best other amplifiers have about 20º of phase shift at the lowest end of the music band, but not this Crown DC amplifier.

It uses internal temperature sensors to ensure that DC offset remains low regardless of operating temperature. There are adjustments inside for technicians to null it even farther if needed.

It has no speaker protection should something go haywire upstream or internally; use speaker fuses in your wiring and no worries.

The chassis and front panel are all solid aluminum extrusions. The power button merely moves an internal industrial click-on power switch, and the knobs are solid billet aluminium.

 

Crown D-150A Series II, rear

Unmounted Crown D-150A Series II. enlarge.

 

IOC LEDs          intro      top

Crown's IOC (Input-Output Comparator) LEDs near the volume controls are brilliant. They compare input to output, and light the LED if anything is even slightly distorted beyond 0.05%.

This way you always know if your signal is clean, or if you're at the hairy edge (occasional blinks), or buried (continuous red). It's easy to push this amplifier and your system to get the maximum real-world power of which this amplifier is capable, regardless of your program material, power line voltage or speaker load.

Yes, this is an amplifier with a lot of internal feedback, but if anything gives rise to any sort of distortion, the IOC LED blinks and you know it before it becomes audible.

The IOCs work great. When I test in the lab, they light instantly and far faster than my lab analyzer lets me know anything's amiss. They make testing this amplifier fast!

Unlike the Crown D-75, there are no SIGNAL LEDs.

 

Proof-of-Performance       intro      top

Crown D 150A Series II box

On the box.

 

They all came with a hand-written laboratory proof-of-performance sheet so you know that your amplifier is performing to specification.

Crown D-150A Series II proof-of-performance

Crown D-150A Series II proof-of-performance sheet. bigger.

 

Crown D-150A Series II proof-of-performance

Back of Crown D-150A Series II proof-of-performance sheet. bigger.

 

History     intro      top

Except for adding features like level controls and IOC LEDs on the front — and the color of the case — all of these amplifiers share essentially the same circuitry based on the original 1968 patent for the DC-300 (patent number 3,493,879).

I haven't tested the older models, but suspect they perform the same.

 

D 150 (1971-1974)

Crown's first 75 WPC stereo amplifier was the D-150. It was introduced as a smaller version of the beastly DC300. Crown advertised the D-150 as having "performance equal to the famous DC-300." It was optimized for studio monitoring and high-end home Hi-Fi use.

It was highlighted against old tube designs; advertised as having an IC operational amplifier front end and "universal load matching" from 4Ω to infinity.

It was not DC coupled, which is why it's the D-150 and not DC-150.

It had a shiny brushed silver top and the dark stripe across its bottom to match the styling of its contemporary IC 150 preamplifier.

It had no front controls. It had two level controls as screwdriver adjustments on the back.

It had no power switch; plug it into a switched output.

It had a solid cast-aluminum back panel with a round Crown logo.

It was marked "D 150" on the front and D-150 on the type sticker on the back.

It was also sold without the front panel, in which case you'll see it sitting on its front with its connectors pointed up when people try to sell them on eBay; they never tell you that it's missing the chrome front. Buy one of these and the front is just a black panel that looks more like the bottom of the unit.

Catalog price in 1971 was the equivalent of $2,500 ($429 list price at the time in 1971 before inflation). The optional 5D walnut case was $200 ($33 at the time in 1971 before inflation).

These aren't that common today.

 

D 150A (1975-1985)

The D 150A's rated power is increased to 80 WPC, although Crown never corrected the sensitivity specifications for this and the D 150A II, both of which should read 1.23 V for rated (80W) output, instead of 1.19 V for rated (75W) output.

The D 150A adds a power switch on the front, and moves the level controls to the front panel. It also adds response all the way to DC.

The D 150A also has a solid cast aluminum rear cover, and was also offered without the front panel, in which case you'll see it sitting on its front panel with its connectors pointing up in the air.

The earliest versions of the D 150A had the a shiny brushed silver front, which was soon changed to matte silver to match the newer IC 150A preamplifier.

Crown soon added the mono switch to the back.

In 1978 Crown added IOC LEDs and changed the Crown logo from round to square.

It says "D 150A" on the front and reads "D150A" on the rear sticker.

These are the most common version found today, about half with IOCs and half without.

 

D-150A Series II (This amplifier; 1986-1991)

This is the newest model, reviewed here but seen less often than the more common D 150A.

This version is all black, and if you look closely, you'll see that Crown mounts it upside-down from earlier models! The output connectors are now much easier to see and reach at the top of the amplifier, and the thinner bar across the front is now at the top. Level controls and power switch and the entire amplifier are now swapped left to right; the whole amplifier is inverted from before.

The front now says "D-150A Series II" and the back is painted "D-150A-2."

This version has a power LED instead of a bulb shining through the Lexan strip as earlier models. The back plate is now painted instead of a solid aluminum casting.

 

Specifications         top

Intro   Specifications   Measurements

Sound   Usage   Recommendations   More

 

Rated Output Power

8 Ω Stereo

80 watts (19.03 dBW) minimum per channel  from 1 ~ 20,000 Hz at 0.05% THD or less.

95 WPC (19.78 dBW) on the back of the performance sheet or 90 WPC (19.54 dBW) in Crown's manual at 1 kHz at 0.1% THD.

You'll see also that Crown elsewhere refers to rated power as 75 WPC (18.75 dBW), especially where it refers to sensitivity.

 

4 Ω Stereo

125 watts (20.97 dBW) minimum from 1 ~ 20,000 Hz at 0.05% THD.

145 to 155 WPC (21.61 ~ 21.90 dBW) at 1 kHz at 0.1% THD.

 

8 Ω Mono

315 watts (24.98 dBW) at 1 kHz at 0.1% THD.

 

16 Ω Mono

160 watts (22.04 dBW) minimum from 1 ~ 20,000 Hz at 0.05% THD.

180 watts at 1 kHz at 0.1% THD.

 

Output Loads

4Ω, 8Ω and 16Ω.

Safe with any load, including shorts — open circuits and reactive loads — although it will kick-in its protection circuitry with 2Ω loads.

 

Topology

It has a standard unregulated linear power supply with ±45V DC rails and dual 9,400 uF 50V capacitors, and an extra low-current 55V rail to help in biasing.

Class A + AB.

The drivers operate in class A at low levels. The output transistors don't turn on until the output demand it, at which point they are class B. The drivers handle all the zero-crossings.

Like almost all Crown linear amplifiers, it's based on the 1968 patent for the DC-300, and you'll see "patent number 3,493,879" on the back.

There's an operational amplifier at the front end, and the IOCs light if the error output of this operational amplifier exceeds a certain value.

 

Input

Two mono ¼" unbalanced phone jacks, 25 kΩ ± 30%.

The inputs feed 25 kΩ potentiometers directly, whose outputs feeds the amplifier.

 

Input Sensitivity

1.19 V ± 2% for rated power into 8Ω.

Sad part is Crown never really comes out and tells us the rated power for this D-150A Series II version.

Since its gain is 20.6x (26.28 dB), 1.19 V in gives us 24.514 V out, or 75 watts for rated power.

There's an internal jumper to increase the gain to 0.775 V sensitivity.

 

Frequency Response

DC ~ 20,000 Hz ± 0.1 dB at 1 watt.

DC ~ 100,000 Hz ± 1 dB at 1 watt.

 

Phase Response

DC ~ 15,000 Hz, +0º -15º at 1 watt.

 

Signal to Noise Ratio

110 dB below "rated power" into 8Ω, 20-20,000 Hz measurement bandwidth.

If you take rated power as 75 W (18.75 dBW), this means -91.25 dBW or 750 pW or 77.46 µV or -82.22 dBV of noise.

If you take rated power as 80 W (19.03 dBW), this means -90.97 dBW or 800 pW or 80 µV or -81.94 dBV of noise.

 

THD

< 0.001% from 20 ~ 400 Hz, increasing linearly to 0.05% at 20,000 Hz at 80 W.

 

IMD

< 0.05% from 10 to 250 mW.

<0.01% from 250 mW to 80 W.

 

Slew Rate

6 V/µS.

 

Damping Factor & Output Impedance

> 400 damping factor into 8 Ω from DC to 400 Hz.

< 15 mΩ in series with < 3 µH output source impedance.

 

Output Connectors

Lab standard 3/4" spaced 5-way binding posts.

Designed for standard MDP lab connectors.

 

Quality

Made in Elkhart, Indiana, USA.

 

Power Input

120 VAC ± 10%, 50 ~ 400 Hz.

Internal taps also for 100 V, 200, 220 and 240 V (all ± 10%).

Red LED power light, although it looks amber when off.

3-wire 5-foot captive cord.

 

Rated Power Consumption

Less than 40 W at idle, 750 W max.

MDX 6.25A rear-panel fuse.

See also Actual Power Consumption.

 

Size

3 RU, 8" deep measured.

5.25 x 19 x 8.75" HWD, depth is behind mounting flange.

133 x 483 x 222 millimeters HWD, depth is behind mounting flange.

 

Weight

24 lbs. (10.9 kg).

 

Export

Crown labeled their export models as Amcron, not Crown.

 

Price, USA

June 2015: about $150 used if you know How to Win at eBay.

The really nice one shown here, complete with original box and lab reports, cost me just $250 delivered. Most you'll see at around $150 have been used professionally and are pretty beaten up; no worries, they're built for that.

 

1991 (D150AII): $1,400, corrected for inflation in 2015 ($795 list price at the time).

1990 (D150AII): $1,400, corrected for inflation ($795 list price at the time).

1989 (D150A2): $1,500, corrected for inflation in 2015 ($795 list price at the time).

1988 (D150A2): $1,500, corrected for inflation in 2015 ($749 list price at the time).

1987 (D150A2): $1,550, corrected for inflation in 2015 ($749 list price at the time).

1986 (D150A2): $1,500, corrected for inflation in 2015 ($699 list price at the time).

1985 (D150A): $1,600, corrected for inflation in 2015 ($729 list price at the time).

1984 (D150A): $1,660, corrected for inflation in 2015 ($729 list price at the time).

1980 (D150A): $1,925, corrected for inflation in 2015 ($669 list price at the time).

1979 (D150): $1,950, corrected for inflation in 2015 ( $599 list price at the time).

1978 (D150A): $2,000, corrected for inflation in 2015 ($549 list price at the time).

1977 (D150A): $1,950, corrected for inflation in 2015 ($499 list price at the time).

1976 (D150A): $2,025, corrected for inflation in 2015 ($489 list price at the time).

1975 (D150A): $2,100, corrected for inflation in 2015 ($479 list price at the time).

1974 (D150): $1,925, corrected for inflation in 2015 ($399 list price at the time).

1973 (D150): $2,125, corrected for inflation in 2015 ($399 list price at the time).

1972 (D150): $2,275, corrected for inflation in 2015 ($399.95 list price at the time).

1971 (D150): $2,500, corrected for inflation in 2015 ($429 list price at the time).

 

Measurements         top

Intro   Specifications   Measurements

Sound   Usage   Recommendations   More

Input Levels & Power Output    Gain   Channel Balance

Frequency Response   Phase Response  

THD   Distortion Components   DFD

Noise & DC Offset   Damping Factors

Bursts    Square Waves

4Ω Performance

Actual Power Consumption

Crown D-150A Series II, rear

Unmounted Crown D-150A Series II. enlarge.

These measurements are made with a state-of-the-art, factory calibrated Rohde & Schwarz UPL laboratory audio analyzer. The traces from the Rohde & Schwarz UPL are color coded for the Left Channel and for the Right Channel. When they don't lie on top of each other, it's due to channel imbalance. When they do lie on top of each other, the trace turns blue.

Unless otherwise specified, all measurements are RMS at 1 kHz at 1 W into 8Ω, both channels driven with a 120 VAC power supply.

These are June, 2015 measurements of a random sample of D-150A Series II made in the early 1990s, bought from a random stranger over eBay. This amplifier is 25 years old and works swell.

As you'll see, with its flawless DC response it really is a straight wire with gain. It's not quite as good as the merely consumer-grade ADCOM GFA-555 II, but it is flatter and does go to DC.

 

Input Levels and Power Output     measurements        top

 

8 Ω

137.8 mV RMS for 1 W output.

435.8 mV RMS for 10 W output.

974.4 mV RMS for 50 W output.

1.195 V RMS for 75 W (24.495 V) output at 0.002% THD.

1.297 V RMS for 88.5 W continuous output at IOC at 0.003% THD.

1.318 V RMS for 91.2 W continuous output at 0.1% THD.

1.384 V RMS for 10 cycles of 1 kHz at 1 Hz PRF for 101 W burst power at IOC.

DC: ±1.655 V DC input for ±33.8 V DC (143 watts DC ) output at IOC.

Driving my 8Ω B&W 801s, I measure about 120W peaks as the IOC flashes. I easily can hit 100W peaks with no light from the IOC.

 

4 Ω

97.5 mV RMS for 1 W output at 0.005% THD.

308.3 mV RMS for 10 W output.

976.5 mV RMS for 100 W output at 0.013 % THD.

1.070 V RMS for 120 W output.

1.170 V RMS for 143 W continuous output at IOC at 0.025 % THD.

1.181 V RMS for 146 W continuous output at 0.1% THD.

1.304 mV RMS for 10 cycles of 1 kHz at 1 Hz PRF for 179 W burst power at IOC.

 

2-2/3 Ω (4Ω in parallel with 8Ω)

80 mV RMS for 1 W output at 0.0065% THD.

253 mV RMS for 10 W output at 0.003% THD.

800 mV RMS for 100 W output at 0.01 % THD.

1.03 V RMS for 165 W continuous output at IOC at 0.05 % THD.

1.03 V RMS for 165 W continuous output at 0.1% THD (it was about the same).

 

Gain     measurements        top

Gain is set by the 510 Ω and 10 kΩ 1% resistors in the feedback network, which calculates to the specified of 20.608x (10,510/510) or 26.28 dB gain.

My sample measures 26.235 dB left, 26.241 dB right, at LEVEL MAX.

Unity gain is at about 37.5, or about 10:30 o'clock.

 
Left
Right
Input for 75 WPC
0 (MAX)
+26.232 dB
+26.242 dB
1.194 V
10
+22.612 dB
+22.067 dB
1.880 V
20
+12.342 dB
+12.559 dB
5.876 V
30
+4.556 dB
+4.891 dB
14.26 V
40
-2.5323 dB
-2.4523 dB
32.66 V
50
-22.165 dB
-26.3 dB
388 V (don't do this)
∞ (MIN)
-85.2 dB
-66.62 dB

 

Gain at DC

20.51x (26.24 dB) left, 20.52x (26.24 dB) right.

YES!!! A real DC amplifier.

 

Channel Balance     measurements        top

At maximum level, the right channel is 0.0064 dB hotter than the left; perfect.

Of course you'll have to balance them yourself at other level control settings; each channel's control is independent and there are no click stops.

 

Frequency Response      measurements    top

Crown D-150A Series II

Frequency response including infrasonics.

YES! Flat to DC. This really is a DC amplifier. Many others like the Hitachi HMA-8500 Mark II claim to be DC, but their servo systems don't let them amplify DC.

Ignore what looks like a -0.05 dB rolloff at 100 milliHertz; that just as well could be an analyzer limitation.

Astounding is that this amplifier is better than most lab equipment: +0.00, -0.06 dB from DC to 20,000 Hz.

 

Crown D-150A Series II

Ultrasonic response.

-1 dB at 75 kHz, swell.

 

Phase Response      measurements    top

Crown D-150A Series II

Phase response.

Whoa! Flat phase response to DC.

 

THD    measurements        top

Crown D-150A Series II

THD versus power.

I tried and tried again wondering what is the hump at 10 mW, and I think I've shown the action of the class A+AB circuit. It looks like the output transistors kick in at about 10 mW in class B, leading to a rise in distortion.

 

Crown D-150A Series II

THD at 5 mW.

 

Crown D-150A Series II

THD at 10 mW.

 

Crown D-150A Series II

THD at 20 mW.

AHA! Distortion really does increase above 10 mW.

 

Crown D-150A Series II

THD at 25 mW.

Distortion is worst at about 25 mW, and tapers off above that.

 

Crown D-150A Series II

THD at 1 W.

 

Crown D-150A Series II

THD at 10 W.

 

Crown D-150A Series II

THD at 50 W.

 

Crown D-150A Series II

THD at 75 W.

 

Crown D-150A Series II

THD at 75 W, 117V AC line voltage.

The THD climbs at subsonic frequencies at high power and low line voltage.

 

Harmonic Distortion Components    measurements        top

Crown D-150A Series II

Harmonic distortion components at 10 mW.

 

Crown D-150A Series II

Harmonic distortion components at 1 W.

 

Crown D-150A Series II

Harmonic distortion components at 75 W.

Standard for a solid-state amplifier; all harmonics are about as strong as the others — but they are also at inaudibly low levels compared to tube amplifiers.

 

DFD    measurements        top

Crown D-150A Series II

19 + 20 kHz difference-frequency distortion at 10 mW.

 

Crown D-150A Series II

19 + 20 kHz difference-frequency distortion at 1 W.

 

Crown D-150A Series II

19 + 20 kHz difference-frequency distortion at 10 W.

 

Crown D-150A Series II

19 + 20 kHz difference-frequency distortion at 48 W.

 

Crown D-150A Series II

19 + 20 kHz difference-frequency distortion at 50 W just before IOC lights.

This is typically good performance.

 

Output Noise & DC Offset    measurements        top

Crown D-150A Series II

Output noise spectrum.

 

 
A Weighted
Unweighted 22kHz BW
MAX LEVEL
-92.5 dBV A
-89 dBV
-6 dB (2:30 o'clock)
-87 dBV A
-84 dBV
MIN LEVEL
-93 dBV A
-90 dBV

Unweighted noise is 117 dB below 80W, or -98 dBW, which is -10 dB SPL unweighted with speakers having a sensitivity of 88 dB SPL at 1W.

The A-weighted noise is 121 dB below 80W, which is equal to -102 dBW, which is -14 dBA SPL with speakers rated at 88dB SPL at 1 W.

Unlike the typically buzzy transformers in the Crown D-75, there is no audible transformer hum directly from the D 150A Series Two. There is some transformer vibration that can become audible if you mount it on a counter or shelf so that the shelf works like a sounding board. These are usually installed in machine rooms away from the speakers, artists and engineers.

This is a very quiet amplifier.

 

DC Offset

+9.9 mV left, +7.8 mV right.

Perfect! Crown's specification is < ± 10 mV.

 

Damping Factors    measurements        top

Damping Factors at 8Ω

 
8 Ω
4 Ω
50 Hz
1,021
511
1 kHz
1,000
500
20 kHz
115
57.6

 

Output Impedances

 
Source Z
50 Hz
7.8 mΩ
1 kHz
8.0 mΩ
20 kHz
69.4 mΩ

 

 

drop
50 Hz
0.0085 dB
1 kHz
0.0087 dB
20 kHz
0.075 dB

 

Crown D-150A Series II

Frequency response driving an 8Ω resistor (green trace) and driving a real B&W CDM2 bookshelf loudspeaker (yellow trace), whose impedance varies between 6 and 45 Ω, a typical loudspeaker load.

This is perfect: +0.06 dB is perfect.

 

Burst Performance     measurements        top

Crown D-150A Series II

Two cycles at 20 Hz.

Perfect; this is what we expect with direct coupling.

 

Crown D-150A Series II

Ten cycles of 1 kHz at 100W at one burst per second.

Perfect; 100W burst power into 8Ω.

 

Crown D-150A Series II

Ten cycles of 1 kHz at 113W at one burst per second.

As expected, the power supply bleeds off and the latter cycles clip — but for one cycle at 1 kHz, you've got 113W RMS available.

 

Square Waves     measurements        top

Crown D-150A Series II

4 Hz square wave.

Perfect; this is what we expect with direct coupling.

 

Crown D-150A Series II

50 Hz square wave.

Perfect; this is what we expect with direct coupling.

 

Crown D-150A Series II

1 kHz square wave.

Perfect, square waves don't get any squarer

 

Crown D-150A Series II

1 kHz square wave.

Perfect, 10 kHz audio square waves are supposed to round-off like this due to the limited bandwidth. We don't want amplification up to radio frequencies.

 

4Ω Operation     measurements        top

Crown D-150A Series II

THD at 1 W into 4Ω.

 

Crown D-150A Series II

THD at 10 W into 4 Ω.

 

Crown D-150A Series II

THD at 100 W into 4 Ω.

 

Crown D-150A Series II

THD at 120 W into 4 Ω.

The THD climbs at subsonic frequencies at high power and low line voltage.

The THD climbs more at high frequencies at 4Ω than at 8Ω. I don't know if this is a limitation of the amplifier, or the fact that my 8Ω loads are precision noninductive loads while my 4Ω loads are cheap wire wound (inductive) power resistors.

 

Actual Power Consumption     measurements        top

There is a strong current surge at turn-on. There is no inrush limiter, so the amp looks like a short-circuit for a moment as the empty capacitors charge. Out of curiosity I replaced the 6.2A fuse with a 1.5A fuse, and it blew out instantly on turn-on..

38 watts at idle, cold.

38.5 (0.4A or 80% power factor) watts at idle, warm.

It draws 61.6 W at 1 WPC.

It draws 270 W at 75 WPC.

It draws 290 W at 88.5 WPC.

It draws 296 W at 91.2 WPC.

It draws 393 W at 100 WPC into 4 Ω.

It draws 459 W at 143 WPC into 4 Ω.

It draws 475 W at 146 WPC into 4 Ω.

It draws 610 W (6.3 A or 81% power factor) at 168 WPC into 2-2/3 Ω.

 

Sound         top

Intro   Specifications   Measurements

Sound   Usage   Recommendations   More

Like most amplifiers, feed it a great signal and feed its output to fantastic speakers in a great environment, and it sounds superbly smooth and detailed.

Feed it a signal from an old source, like an HD file of classic 1970s rock, and you'll very clearly hear tape saturation when it happens. This clean amplifier makes tape overload very obvious; it doesn't gloss it over like a tube amp might.

As a DC amplifier, there are no signal coupling capacitors! Gone are the numerous electrolytic capacitors in the signal and bypass paths of a typical solid state amplifier. Yes, there are some high-frequency capacitors for preventing oscillation, but gone are the coupling capacitors usually present, which goes a long way in cleaning up the sound.

It's completely phase coherent. There is none of the low-frequency time misalignment of other amplifiers, not that we can hear that.

Its outputs are silent, much better than active speakers more popular today.

This is a typically good solid-state amplifier; it has no sound of its own. Whatever goes in is what comes out, and if there is any sort of distortion or other problem, the IOC lights to warn you before it becomes audible.

People get all flustered changing-out amplifiers and imagining all sorts of things from one to the next, but when you set these up under tightly controlled conditions, there isn't much, if any, audible difference between most good solid-state amplifiers.

Yes, I head some deep bass in some Pink Floyd albums I had never heard before, but that's probably because I hadn't played those since the 1980s before I had my B&W 801s that go that deep.

It lacks the euphonic colorations and distortions of tube amplifiers. As a professional product, it lives to serve by faithfully reproducing what it's fed, not trying to make music sound even better than it is.

What goes in is what comes out. It sounds great with the right inputs and great speakers, but crappy with the wrong ones. What you hear is what you've got.

 

Usage         top

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Crown D-150A Series II, rear

Rear, unmounted Crown D-150A Series II. enlarge.

Mounting

This is a professional rack-mount amplifier. It has no feet. You won't get a wooden case with it; buy one separately as I did.

Mount them in a standard 19" rack, or a nice 19" wooden case as shown at the top.

If you can't find a rack or wooden case, peel-and-stick feet work great. Put it on cardboard or a magazine when you first get it so you don't damage your furniture.

It cools itself without a fan. It will get hot if you wrap it in a blanket; let it breath. It loves being rack-mounted, in which case the head conducts through the rack mount.

 

Power Connections

It has a grounded captive plug and cord.

Crown says use a cheater plug to disconnect the ground pin if you need to — but at your own risk.

There is no turn-on delay, so make sure that whatever's upstream of this either has its own turn-on delay as all good processors have, or at least that they don't have any power-on thumps. If they do have thumps, turn this amplifier on last.

 

Inputs

For Hi-Fi use, use two ¼" to RCA adapters for an unbalanced input. This is much better than jock-strapping a balanced inputs as you have to do with most other professional amplifiers.

For home Hi-Fi use, these unbalanced inputs are perfect.

 

Output Connections

The lab-standard banana jacks are always connected; there is no relay.

Use a standard 3/4" spaced dual banana MDP plug for connecting speaker wire.

Always use insulated plugs, never amateur metal ones that can be accidentally shorted.

Yes, it's simple to use lugs or even bare wire if you prefer; that's the beauty of the professional jacks on the back.

It is difficult to reach all the way to the speaker connections when in a case. Be sure to use standard 3/4" spaced dual-banana MDP plugs, which are included when this amplifier is sold new, for the best and easiest way to connect to the outputs.

This amplifier has loads of protection to protect it from you and from itself, but has no speaker protection. Use fuses with your speakers. I do, and when sold new Crown included fuse holders and wire nuts so you'd have no excuse not to use fuses.

 

Mono Use

It's trivial to switch these to mono mode with a switch on the back.

The gotcha is that the output terminals are not arranged to accept a standard 3/4" spaced dual-banana MDP plug; you'll haver to figure out some other way to connect to the two hot terminals which are spaced farther away.

 

Levels

If used with a preamplifier, you'll get less noise if you turn the volume controls down to optimize the system gain so the maximum output of the preamplifier is just enough to overdrive the D-150A Series II by a small margin.

In most preamplifier setups, leaving the volume controls all the way up picks up more noise in the line from the preamp, and has you turning the preamplifier level way down.

I usually run my D-150A Series II level controls at about 20 (about 2:30 o'clock), which gives an optimum input range for use with most good preamplifiers. This gives quieter results than with most amplifiers or with leaving the controls at maximum.

There are no click stops; the knobs rotate continuously.

What looks like an index mark is actually cut out of the knobs, making it easy to set the level scale ticks precisely.

 

Electrostatic Speakers

Crown cautions to use a capacitor as a DC bypass if you're driving a transformer input. There are diagrams in the manual.

 

Recommendations         top

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If you want great sound, get a tube amplifier. If you want fantastic build quality and accurate sound inexpensively, get one of these.

I love this amplifier because it's so darn handsome, especially with its solid aluminum knobs.

It performs great, and the market is so flooded in 2015 that they are a bargain for Hi-Fi use.

it's also a great laboratory amplifier. It's designed to be stupid-proof, and amplifies to within +0, -0.06 dB from DC to 20,000 Hz. It's ideal for loudspeaker testing as it adds no phase or time distortions at low frequencies.

With bottomless DC bass and quiet operation, the crazy might want to direct-wire the outputs to Audeze headphones for the ultimate dynamic headphone experience — but be careful because this amplifier can blow-out those headphones as well as your hearing if played foolishly loud.

The amplifier is very well protected against you or itself, but like most amplifiers it offers no speaker protection. Use fuses in-line with your speakers.

You can pay more, but you can't get a better sounding solid-state amplifier. Used with the right sources and speakers, you'll revel in the clean, smooth and detailed sound of the concert hall rising from inky-black silence, but slum it with mediocre recordings or cheap-out on your speakers, and you'll get what you deserve. This amplifier tells it like it is; it doesn't sweeten anything.

Your amplifier is the last thing about which you should worry. Your choice of power amplifier is the least critical part of your music reproduction chain; they all sound about the same. If your budget is limited, it's better to save money with this amplifier and pour the rest into your loudspeakers and your music collection.

If you use JBL speakers and/or want to hear your classic rock the way it was performed and recorded, Crown is the way to go. In its time, these were used in all studios and concert venues.

It has more than enough power to drive my B&W 801s and 802s to much louder levels than I need. The IOCs never light unless I just want to see how loud it will go. Only the truly deaf need a DC-300. The difference between 80 WPC and the 155 WPC DC-300 is only 3 dB, or one or two volume control clicks.

People get all excited hearing things that aren't there, but when you batten down all the variables so you just hear the amp, it's no big deal. This amplifier sounds pretty much like every other decent solid-state amplifier.

These make fantastic amplifiers for passive subwoofers because they have perfect amplitude, phase and group delay response right down to DC. You won't be adding any more poles or zeros in your transfer function when you use one of these as your low-frequency amplifier.

If you want an inexpensive and indestructible professional amplifier, here you go.

Unlike consumer amplifiers, play it as loud as you want, and so long as the IOC LEDs don't light, you're not distorting and what's coming out is exactly what went in — just louder.

Enjoy!

 

More Information         top

Intro   Specifications   Measurements

Sound   Usage   Recommendations   More

 

D 150A Series II Datasheet

 

D 150A Series II Schematic

 

D 150A Series II Owner's Manual 1 of 4

D 150A Series II Owner's Manual 2 of 4

D 150A Series II Owner's Manual 3 of 4

D 150A Series II Owner's Manual 4 of 4

 

D 150A Series II Service Manual 1 of 6

D 150A Series II Service Manual 2 of 6

D 150A Series II Service Manual 3 of 6

D 150A Series II Service Manual 4 of 6

D 150A Series II Service Manual 5 of 6

D 150A Series II Service Manual 6 of 6

 

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05 June 2015