Axiom Home Page Forums General Discussion Technical Questions Digital Receivers

I am in the market for a receiver for a home theater setup. I have come across the Harman Kardon digital receiver DPR 1001, but no one so far has been able to tell me the advantages/disadvantages between it and analog receivers. Up till now, I was thinking of getting a HK 2 or 3 series, but I have noticed places selling this digital one for $500 (it is approx. $1000 msrp). I will be putting the receiver on a bottom shelf of an enclosed entertainment center that will have to have the door open when it is playing. I know the digital receivers run a lot cooler, but if they do not have comparable THD % levels, I don't know if I would want it. Does anyone know if digital amps will be to analog receivers as digital cameras are to film cameras (i.e. destined to replace them)? Thanks for any help!

I went to the local circuit city and compared the AVR 1001 to the AVR 1083? (Not sure about the model number, but it was priced about $1000).

There was a very distinct difference between the two. The source was the Fellowship of the Ring DVD, and we were using the same speakers, just A/Bing the receivers.

At first I liked the analog better, its the kind of sound Im used to hearing. But after a few minutes I liked the digital much better. The bass was much more clear and the treble was more subtle (not as loud or "glary") but more clear as well.

When I upgrade it will definately be to a digital receiver.

Hi,

The main virtue of Harman's Digital Path receiver design (in the 1001, 2005, 1005) is the elimination of a large, heavy tranformer and the gain in efficiency and cool running of a digital switching power supply. There are also fewer analog-to-digital (A/D) and digital-to-analog (D/A) conversions of a signal passing through the processing and gain stages of the receiver, which in theory eliminates possible digital artifacts.

That's all well and good if you start with a digital signal from a CD player or DVD player, but if you plug in an analog source, the audio signal still goes through A/D conversion. And in the final output stage, the digital signal is converted to an analog form, which must occur because current speakers only handle analog input signals.

You're correct that total harmonic distortion figure specs (THD) are higher (0.15%) than H/K's conventional receivers, which specify THD at 0.07%. But 0.15% is still far below audibility with music signals and many orders of magnitude less than early solid-state amplifiers, which often had THD of 0.5% to 0.9%.

On the other hand, the audio bandwidth of H/K's DPR 1001 and the newer models (DPR 1005 and 2005) is limited to 20 kHz at the top end, compared to 130 kHz for H/Ks conventional receivers. If you believe human hearing extends beyond 20 kHz --- I do not, nor has it ever been scientifically proven or demonstrated -- then the DPR 1001 won't do it for you, whereas conventional H/K receivers will.

Noise figures are in the same region as conventional amplifiers and receivers (IHF-A) at -97 dB, which is far below audibility. I've not seen thorough bench tests of these new digital receivers to see if there are other liabilities that may emerge. Digital switching power supplies must be very well shielded against radiating ultra-high frequency RF garbage, but it seems that is now well controlled.

Regards,

Its entirely possible that some of the differences I heard were because of receiver settings. Im just really starting to learn about the characteristics of speakers and components. The salesperson tried to set them as closely as possible so we could get a true A/B test (at least as much as a Circuit City music room will allow). The salesman, my wife and I, all agreed that there were noticable differences between the digital and analog receivers.

I guess on thinking back and reading your description Alan, I am less inclined to say it sounded "better"...it was just "different". I prefer the sound of the digital receiver, but it might indeed by technically inferior?

Thanks, Alan. I guess it is too early to tell about reliability for these digital receivers. I am worried about putting out $500 or more and not having it last as long as a conventional receiver. By the way, what is the life expectancy of analog receivers?

Thanks for the info. I also heard the digital receiver when I went to circuit city, although I was concentrating on the speakers, not the receiver. I don't know if my ear would know the difference or not.

The life expectancy of an analog receiver is about 30 years give or take (also dependant on use).
Ok, well no one really knows what the life expectancy is but realistically these electronics could last you a lifetime.
Now if you are referring to the technology onboard the receiver, like the all important DAC for Dolby and DTS, well that expectant lifetime is anywhere from a couple of months to several years i would say. Some of the new, higher priced receivers are offering computer connectivity for updates to the software/firmware of the DACs onboard the receiver.
Even still, 5.1 today should do you just fine for a darn good long time. Heck, there are stereophiles out there who still snub their noses at the mere concept of surround channels and stereo has been around for...how many decades now?

Do not be so concerned with what is in style and what MIGHT be in style in the next xy period of time. Something you buy today will always be out of date by next year. Digital vs. analog receivers? Right now alot of hype and questionable as to the enhancement o signal it will bring. The terms 'upgrade' and 'better' are often abused as adjectives in this audio realm.

And that is the rant for the day.

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The life expectancy of an analog receiver is about 30 years give or take (also dependant on use).

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Hmm.. the atomic half life of copper and silicon are...



Bren R.

I see, and the half-life of capacitors is what?

Only radioactive isotopes have half-lives. Any degradation that happens is not due to particle decay. Last time I brought my geiger counter near my stereo equipment, I didn't get a single click -- until my cell phone started ringing and then it went berserk!



No, I don't have a geiger counter.

I was KIDDING about the life expectancy.
OH, waitaminute, i see what threw you boys for a loop.
I forgot the smiley laughy faces.
Here ya go kids

Hmmm, 33 years for the Pioneer receiver and a woofer dying at 32 years.
I would say my earlier estimate of a lifetime for a receiver was pretty darn close.

Now Bren, get back to work on that arena. We need to hurry to get the Jets back in the Peg and you are holding us up.

Hi,

If you keep the switches, pots (potentiometers) and other controls clean and prevent oxidation over time, solid-state electronics are an incredible bargain. I'd estimate at least 15 to 20 years. I talk to customers who have 20-year-old stereo receivers and integrated amps that still work fine, and I've got older solid-state amps that work perfectly but I do clean the switches and pots every five years or so or whenever they get noisy or intermittent.

In theory, a "digital" amp might sound audibly cleaner, but I'd want to do blind instantaneous comparisons with tone-control circuits switched out before I'd make a judgment.

Eventually heat gets to everything--the values of resistors and capacitors may drift over many years--but it's hard to estimate long-term reliability of ICs. Sometimes stray voltage or static electricity can knock those out. But by comparison to tube gear, which begins to deteriorate from the moment you turn it on (and the tubes themselves change with use), solid-state designs are very long-lived.

Regards,

Any tips on cleaning the things? I've got an old Marantz 2220B and I'm pretty sure all it needs is a new fuse for the lights and a good cleaning, but I can't even figure out what to clean after I get in the thing. And RS didn't have the spray on cleaner the last time I checked, just a stupid pen that's only good for cleaning Atari cartridges.

If you have many components in a closed-front entertainment console, I strongly suggest putting a small cooling fan in the back. It's very easy to cut a circular hole in the thin rear panel and mount a small, quiet ball bearing muffin fan. It makes a big improvement in component life and safety. Before I did this my digital cable box got so hot I couldn't put my hand on it; afterwards it was barely warm. Just one small fan mounted almost anywhere will be a huge improvement in a closed-front console.

Joe, that's why Axiom should hook up with the folks at Flying Mole Digital Amplifiers. 160 watt monoblocks which weigh 1.4 lbs each, about 8"x5"x2", digital - cool running, and as sweet as a Single End Triode Tube amp.

I tell you friends, I have a feeling, that whoever comes out with a digitally amped speaker will own the market.

Just look for contact cleaner (the spray type, ether based - NOT silicone based!) and don't use it on live equipment - it's a conductor and flammable.

Bren R.

Anything people recommend? I'm sure it's really all the same, but still...

Hello kcarlile

I personally stay away from ether based cleaners. I prefer Caig Labs products. You can find them here:

http://www.caig.com/

Polyphenyl ether (?) is just a basic surfactant (ie: cleaner)... no brand preference here... whatever's on the workbench is what I/we use. Just shoot it on ICs, connectors, switches, pots and anything else that needs some cleaning (stay away from manual tuners though). Generally speaking the stuff is pretty inert, just let it thoroughly evaporate before putting power back in.

Bren R.

Ah. The 2220B has a manual tuner in it. I assume it does something nasty to the rubber?

I just don't like breathing the stuff, and do worry about instantly removing all facial hair in a mini fireball.

The De-Oxit spray from Caig.com works wonders on older equipment. I resurrected an old Sanyo amp / reciever I had from the 80's...and an old Nikko for my neighbor across the street. You have to open the case and using the extension tube, find the pots small openings, spray some in and rotate a number of times from extreme to extreme. After it evaporates, fire it back up. You'll be suprised at the improvement...Been my experience...

My .02,

WhatFurrer

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Ah. The 2220B has a manual tuner in it. I assume it does something nasty to the rubber?

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Whoops, was going to respond to this earlier and forgot... I just wouldn't try cleaning a manual tuner with anything stronger than isopropyl alcohol... if they slip, the dial becomes useless, kind of finicky things.

Best results for cleaning is IPA (isopropyl alcohol) @ 100%; off the shelf "rubbing alcohol" is 70% IPA/30% de-ionized water usually... but sometimes can contain ethanol in some volume, not sure if it IS detrimental to electronics but I won't take the chance of using Russian vodka to clean my pots.

Bren R.

Methanol, ethanol and 2-propanol (aka isopropyl alcohol) are all fantastic cleaning chemicals with extraordinarily similar properties.
The longer carbon chain, yet still polar propanol makes it slightly better for removing grease type substances. It is also slightly less toxic than methanol if i remember correctly.
Ethanol should not bother your components although it is best consumed orally rather than poured onto cleaning rags for the wasting.
Save the Russian Vodka for the $20 speaker set with the shrilly high end. It might help tone down the high end a bit with a slightly laid back slur. The more you apply, the more laid back it gets!

Frightens me that the two guys from Manitoba are posting the most about ethanol and denatured alcohols.

Bren R.

As long as I can spray it, no problem. But I don't have the skill to take it apart very far. I'll try out the isopropyl, though. Thanks!

[nitpick]
It's impossible to have 100% isopropyl alcohol. As soon as it's exposed to air, it dilutes by absorbing moisture.

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It's impossible to have 100% isopropyl alcohol.

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Like 0dBFS (NOMINAL)?

Bren R.

More like "My sub goes down to 0 Hz! And it consumes no power doing so!"

"Nigel: These go to eleven."