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Review: Harman Kardon avr2650 Multichamp

Category: Amplifiers

The big gift under the Christmas tree this year with my name on it turned out to be a Harman Kardon avr2650 7.1 95wx2. My sister informed me that it was my access to the internet--an intimidating thought. In my entrenched 2-channel universe, my idea of an avr was to use it for biamping, triamping--you could quad-amp with subs.

So I started by setting it up as 2-channel with the biggest vintage AR's I thought it could handle--the 93 3-way floorstanders with four drivers at 6 ohms, 87spl. I added the PDR10 V.3 subs, which are not good subs by the way but the only ones I have and used my HK HD990 cdp as source.

Dolby Volume, widely available on mid-fi avr's, was set on medium, and I left it on and left the room EQ off and was amazed by the sound quality which was preferable to Dolby Volume turned off. Highs were crisp and clean; overall sound was tight; tonal qualities became rich with break-in. And all easy on the ears. I had stopped listening to Dave Matthews "Crash" on RCA label because of the harsh edge. But Dolby Volume had the cure. Piano on Jacques Lousier Trio "The Best of Play Bach" was smooth as silk. All disks were given a more pleasant quality. I thought, I've been living in the woods in Minnesota in January too long. A mid-fi avr can't sound this good.

I went to the net in search of reality and found two reviews of the flagship avr3650. One is www.hometheatre.com/content/harman-kardon-avr-3650. The other one fell into the black hole of cyberspace. But both critics were impressed with 2-channel listening using Dolby Volume. I read, "Harman Kardon has taken the road less travelled" and "a music lover's dream". It seemed that these critics too were living in the woods in Minnesota.

I went to the Dolby Labs website for an explanation of Dolby Volume. I quote, "Dolby Volume goes well beyond providing, consistent volume level. It also maintains the sonic balance of the mix.." and provides "..what we call reference quality sound". While this description is wrapped in enigma, it implies an engineering of the signal which would then depend on the ability of the amplifier to faithfully amplify the Dolby Volume. Put another way, it gave me enough to hang on to so that I could believe what I was hearing.

It should be noted that the flagship avr3650, avr2650,and the 5.1 editions 365 and 265 all have the same owner's manual with all the same specs except for the power ratings. Even HCC is the same for all of this series at 35 amps. The newest avr1700 is a slightly different animal with THD at .1% compared to the avr3650 series at .09% and weighing a few pounds less. The buyer needs to know as well that the avr3650 series is not equipped with every available feature or every bell and whistle, for example S video. And the owner needs to know that the owner's manual supplied is abbreviated and that the complete manual needs to be downloaded from the HK website--unless the owner knows that the avr button must be pressed in order to access the menu. If the owner already knows that and is agile with these avr creatures, then maybe not.

I still haven't set up the surround. I ordered a pair of Paul Speltz' autoformers. I'm going to configure them to the maximum impedence with a larger, more revealing, more reference quality speaker--a better test. Such is the madness that belongs to my 2-channel universe.

Associated gear
HK HD990
vintage AR93Q speakers
Paradigm PDR10 v.3+

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arnettpartners
5 responses Add your response
arnettpartners OP
312 posts
 
Hi Al,

I did some subsequent homework from the lit included with the autoformers and which is also available on the website: www.paulzpeltz.com. In the chapter Technical Sidebar, Paul supports your comments on currently made speakers which are 4 ohms or even less. He cites an Apogee speaker which he says is 1 ohm and Martin Logan, Krell, and Audio Physic as examples of other "offenders". He distinguishes between efficiency ratings and sensitivity ratings. He says that sensstivity ratings are a form of cheating--my words, not his--and that they do not reflect actual SPL. He wants the word to get out and for people to put pressure on the speaker companies and also to buy his autoformers.

I also played a little more with the autoformers. There is a 3x tap on this model which I think would give me 12 ohms, and I auditioned that configuration. But it was a downgrade from gorgeous on 2x to somewhat dull on 3x. So 2x is ideal for my amp and speakers, and I'm done experimenting.

Very helpful blog on understanding the playback of cd's and cd-r's. Streaming is the goal.

Thanks for all your support which was much needed.

Best,

Lynne
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almarg
9,670 posts
 
Hi Lynne,
So I have 95w x 2 driving them. Right?
Yes.
Probably no one makes 4 ohm speakers anymore, but it should be against the law. They saturate amps and probably even the speaker crossovers.
Actually, there are still lots of 4 ohm speakers that are made. One reason among several being that solid state amplifiers can provide more power into 4 ohms than into 8 ohms, in many cases twice as much. Although amplifiers often will have higher distortion and won't sound as good doing so, compared to when they are working into a higher impedance.
If I take a disk with poor sound quality and burn a copy with my HP pc, the copy sounds better than the original.
That phenomenon, while counter-intuitive, has been reported by a lot of people, and can be explained in a plausible manner. See my post here.

Enjoy!

-- Al
arnettpartners OP
312 posts
 
Al and company,

The autoformers arrived 2 days ago, and in the meantime my brain started working again. I failed to mention that the speakers I wanted to use with the avr are 4 ohm speakers. So I used the 2x impedence ratio to turn them into 8 ohm speakers. I haven't even tried 4x yet since you have pointed out that I will lose amplifier power. So I have 95w x 2 driving them. Right? Even so I had to add the powered subs. I didn't even try not using them. These AR 90's are one step down from the AR9--4 way speakers with 2 10" side firing woofers, 87spl. They are a little shy of 4 ft tall and weigh 82 lbs.

With the subs biamping them, the avr damps them very well. The sound is wonderful. It's open and natural and full. The piano attack on The Holly Cole Trio "Don't Smoke in Bed" just about goes right through you. Dolby Volume processes each channel separately, and I think channel separation is very wide. It sounds to me like dual mono sounds--really clean with a good sound stage. The subs need upgrading and base management fine tuned for sure, but I'm going to have to keep these autoformers. I have to say it's the craziest system I've ever heard of.

Why did they ever make 4 ohm speakers? To get more decibles of sound? To get a fuller sound? All Revel speakers are 6 ohms and Paradigm are 6 and 8 ohms. Probably no one makes 4 ohm speakers anymore, but it should be against the law. They saturate amps and probably even the speaker crossovers.

And do some of these processors have an inability to quantify all the distortion components in a signal? If I take a disk with poor sound quality and burn a copy with my HP pc, the copy sounds better than the original. If I run a disk through an HK DMC1000, the streamed playback sounds better than the original. Streamed content has the potential for sounding better than a cd. And Dolby Volume sounds better than the raw cd. But Dolby Volume sounds better than anything.

I have many more trials and possiblilities with the autoformers. I talked again to Paul Speltz. He said about 5% of his customers have solid state amps. He said they use them on the Nelson Pass ALF(?) amps, the low powered ones. He said that MOSFETS are noisy and the autoformers cut the noise in half. He said his only experience with solid state was that he used them with a Sony avr and they upgraded it from unlistenable to listenable. He said they have a smoothing effect on the audio. I can say that they have a place in solid state for 4 ohm speakers which I'm guessing are quite rare these days.

Best Regards,

Lynne
arnettpartners OP
312 posts
 
Al,

Thank you so much. You made my year. I wondered if there would be a glitch in my David-Goliath hypothesis, and you have explained it to me. I did call Paul before I sent the check because I seemed to remember that there was a trial period, and there is a 60 day trial period. OK, Paul manufactures these autoformers mostly for tube amps, then. Wondered why I didn't hear more about them. They haven't come yet, but I'll see what I can do with them and let you know.

Very Best Regards,

Lynne
almarg's avatar
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almarg
9,670 posts
 
Beautifully done review, Lynne. Enjoy!

Regarding the autoformers, a point to keep in mind is that although chances are that increasing the load impedance that is seen by the AVR will make it possible for it to provide somewhat better sound quality (and will also, btw, reduce the sonic effects that may be caused by the speaker cables), there will be a reduction in the maximum amount of power the AVR will be able to deliver to the speakers.

For example, if you were to multiply a 6 ohm speaker impedance to 12 ohms, using the 2x impedance ratio the autoformers can provide, the 95 watt/8 ohm/2 channel rating of the AVR would be reduced to approximately 63 watts. That's not a whole lot of difference, amounting to only about 1.8 db. But if you were to use the 4x impedance ratio with a 6 ohm speaker, resulting in 24 ohms being seen by the AVR, it would only be capable of about 32 watts, a reduction of about 4.8 db.

It would be a different story with an amplifier having a tube output stage, but those numbers will approximately hold true for nearly all solid state amplifiers.

Best regards,
-- Al
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