Class-D at Sharper Image

[Pano]

I was cruising thru the Sharper Image store at the mall today. They have a lot of audio "junk" on the floor. 2 devices caught my eye, if not my ears. Both with class-D amps. One with tubes.

1st:
Class-T iPod system.

Have seen the little speakers before, but not the iPod dock. The dock must have a Tripath chip, because it claims to be "Class-T". Sounded pretty bad. I blame the speakers, of course. Having heard how the little JohnBlue JB3s can fill a room, these were anemic. But much cheaper, of course. They look cool, that's about it.


2nd:
Philips Micro System

A pretty little DVD/CD/Radio/combo with an amp under it and a matching pair of speakers. Blue lights on the sides, of course!

The amp has "hi-fi" tubes just visible behind smoked glass. Kind of like the old Luxman integrated amp of the 80s. Display has a preheat count down when you turn on the amp - cute.

Didn't sound worth a damn, but again I blame the cheap speakers.

Yeah, I know this isn't DIY, but it was fun to see the class-d stuff in a mainstream shop. You'll not catch me spending that much just to play around with either of these toys, although the Philips is tempting...

[toolkit]

Did you also notice the Philips "Features a motorized tray for playing a DVD or CD"? This is cutting-edge stuff alright!

[Pano]

It does, it does! And it works. Push the button and the tray slides out. Push it again and it slides in. Wow! What will they think of next???

To be fair to the little Philips, it a nice looking design, well built - even the blue lights around the wood panels on the side is not all that cheesy. The rest of it is fairly classy looking.

I remember the awful, ugly junk that was available at an equivalent price in the 70's and 80s. Really awful, cheap and shoddy. We've come a long way. Every decade has it good and bad (just have a look around Sharper Image for this decade's bad) but the 1970s and 80s seemed to have been the nadir for consumer design and quality. IMO, of course.

[speaker]

Originally posted by panomaniac
To be fair to the little Philips, it a nice looking design, well built - even the blue lights around the wood panels on the side is not all that cheesy. The rest of it is fairly classy looking. [/B]

Quite honestly, I think it is one of the sharpest looking pieces of kit to come out in awhile.

[raintalk]

I would wager that "glow" is simulated. Backlit LED's like guitar pedals do. I can't help but think the "tube" is just a big fat gimmick. If the musician I'm listening too recorded with a tube I'll be glad to hear what the artist did and not what some marketing designer at Philips thinks I should hear.

[Pano]

Well, the tubes do seem to be behind a rather dark glass. At least on the old Luxman you could see them.

Nothing wrong with tubes. Done right they can be more neutral than most transisitor circuits. If, however, they are used to "flavor" the sound, it's just a gimmik.

[buzz1939]

Well, if you want to DIY, order one of these Philips refurbs - very compact, similar design.

http://www.outlet.philips.com/b2c_re...72&shop=OUTLET

Amazon says the 708 is Class D (link ), not certain about the 703 but the design is similar.

The DIY part is keeping it working and dealing with the fact that Philips sends true refurbs, not overstocks / like new, etc that you get from some other places.

And potentially swapping out the speakers, though at least on the 703 they are better than you'd expect.

[marconist]

Originally posted by panomaniac

The amp has "hi-fi" tubes just visible behind smoked glass. Kind of like the old Luxman integrated amp of the 80s. Display has a preheat count down when you turn on the amp - cute.

Didn't sound worth a damn, but again I blame the cheap speakers.

Quite right. The thingy itself gives out a good sound!

The tubes are however actually in the circuit. This is lowering the s/n ratio. Kicking out the tubes will make it a HiFi capable thing!

[Pano]

Nice find on the refurb units, Buzz! Might be fun at that price.

Macronist: So you have actually heard one with good speakers? You liked the amp?

Does anyone know what flavor of class-d they use?

[marconist]

Originally posted by panomaniac

Macronist: So you have actually heard one with good speakers? You liked the amp?

Does anyone know what flavor of class-d they use? [/B]

Even if you well install it with the original speakers its quite nice.
Connecting a couple of big (T+A) frontspeakers is a vast improvement, the electronics are really nice.
Except the fact that you have some hiss!!! To my opinion this is caused by just throwing in a couple of tubes for the sake of marketing.
An even simpler (and cheaper) unit (dont know the number by head) has the same quality sound but no hiss.

I suppose they use here a chip integrated class D solution, like in the unit I mentioned above. UcD they also use, but mostly as a sort of standard module in slightly more expensive models.


The specs of the thingy you saw:

SYSTEM
Power supply .......................................... 120 V / 60 Hz
Rated working power consumption (1/8 rated
output power) .................................................. ...... ≤ 85W
AUX input sensitivity ..................................... ≤ 500mV
Channel Separation ............................................. ≥ 40dB
Distortion .................................................. ..................... 0.7%
Eco power Standby ................................................ < 1W

DVD
Frequency response 100Hz-20kHz (+0.5/-2 dB)
Video output .................................................. .............. 1 VP-P
HDMI 480p (60Hz), 720p (60Hz), 1080i (60Hz),
576p (50Hz), 720p (50Hz), 1080i (50Hz)
Horizontal definition ................................... 500 (TV)
Dimensions .... 250 (W) x 90 (H) x 180 (D) mm
Weight .................................................. ........................ 2.3 kg

AMPLIFIER
Rated output power (THD = 10%) ..........................
.................................................. ........................ 2x75W (4Ω)
Frequency response 100Hz-20kHz (+0.5/-2 dB)
S/N Ratio .................................................. ................. ≥ 60dB
Loaded impedance .................................................. ... 4 Ω
Dimensions .... 250 (W) x 90 (H) x 180 (D) mm
Weight .................................................. ..................... 4.35 kg

TUNER
FM Frequency range .......................... 87.5-108 MHz
FM Noise limit sensitivity .......................... ≤ 20μ V/M
FM S/N .................................................. ...................... ≥ 46dB
AM wave range .................................. 520 – 1710 kHz
AM Noise limit sensitivity ....................... ≤ 3.0m V/m
AM S/N .................................................. .................... ≥ 40dB

Specifications
SPEAKER
Impedance......................................... ............................... 4 Ω
Input power .................................................. ................ 75W
Sensitivity .................................................. ............ 80 ± 4dB
Frequency response ................................ 80Hz-16kHz
Dimensions . 205 (W) x 329 (H) x 240 (D) mm
Weight .................................................. .......... 6.82 kg each
REMOTE
Distance .................................................. .............................6m
Angle .................................................. ............................. ± 300
Specifications subject to change without
prior notice


You see in the Amplifier spec why it is hissing a bit!


It comes from the user manual:
http://www.p4c.philips.com/files/m/m...37_dfu_aen.pdf

The Euromodel is the same except for the mains voltage.


For the fanatics: Philips is not difficult with manuals. You might try and order one at www.doknet.nl . They have an English mode and newer stuff is delivered on CD as PDF.