Denon AVR-2807 Mini-Review

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eezip
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Denon AVR-2807 Mini-Review

Postby eezip » Thu Dec 07, 2006 1:05 am

I finally broke down and replaced my much beloved but outdated H/K AVR235 with a Denon AVR-2807. I was deciding between the Denon and Yamaha RX-V2700. The Yamaha added USB and network functionality plus HD upconversion. However, with an upconverting DVD player and HD set top box, the upconversion would only be used on broadcast TV. And since I mostly listen to hard media in the living room and soft media on my computer, I couldn't justify the hefty price increase. Plus, I got a good deal :)

I brought the receiver into work and ran some audio performance tests and have gotten to play with it a bit and thought you guys might be interested in how it performed both on the bench and in my home. I'm not going to post any of the graphs/data, but I will describe the performance in words. Keep in mind this is one single set of tests of one single unit. Also, please let me know if there's something I left out, I didn't describe well, and how you feel about posts like this. I'm hoping this might help someone trying to make the same decision I just made, as well as be interesting to read for anyone, and any feedback is welcomed.

Amplifier:
I used the external 7.1 input to feed analog signal directly to the amplifiers. All loads were 8ohm nominal non-inductive resistors. Because I lacked a splitter to route signal to more than 2 channels, I was only able to obtain 1 and 2 channel power measurements. The amplifier is discrete and on many boards, all single layer. All power measurements were made with an 80kHz filter [this is typical for linear amplifiers].
All 7 channels matched very closely in frequency response. The -3dB point was well above 100kHz.
SNR, with 60Hz notched out, was greater than 98dB with a bandwidth of 22-80kHz and over 104dB when A-weighted full bandwidth in all channels.
One channel driven power was nearly 150W at 1% THD.
With 2 channels driven all channels met or exceeded 120W at 1% THD for the entire audio bandwidth [20-20kHz]. 20kHz signals were between 0.01 and 0.02% THD until clipping while 2kHz and lower frequencies were in the 0.004-0.002% range! This handily beats their rated performance.
The amplifier went into protection during a full power run into 2ohm where 260W were noted at 1% THD. The shutdown effectively protected the amp and nowhere else was I able to trigger protection.

PURE DIRECT mode:
I continued testing amplifier performance but putting the unit into PURE DIRECT mode and testing the front 2 channels. Not only did this allow me to use both available channels so I was using the full capability of the amp in this mode, but I also wanted to see if shutting off the 'extraneous' circuits would improve the amp's performance any.
Frequency response curves shift up and down by an inaudible amount when moving from no load to 8ohm load to 4ohm load.
Worst case crosstalk [between Fl and FR channels, of course] is -57dB at 20kHz and flat from 1kHz and lower at -75dB. This is quite adequate but not exemplary performance.
SNR curves show a strong 60Hz and harmonic content. Still wideband SNR measurements with A-weighting were -107dB so the PURE DIRECT mode does have benefits. The improvement, however, would be inaudible.
THD vs power didn't change from the results above.
THD vs frequency showed sub-0.01% THD below 10kHz at full power and -10dB from full power. At -20dB THD was mostly flat at all frequencies and right around 0.01%. -30dB full power performance was very flat and hovered at 0.035%.

Digital Input:
I used an optical in with 48kHz signals and took measurements from the FL and FR 7.1 preouts. Because my AP can only create stereo S/PDIF signals, and I noted excellent channel-to-channel results above, I'm fairly confident all channels would be very similar to the stereo testing I performed. The DACs are said to be Burr-Brown PCM1791. I measured nearly 5.5VRMS output before nothing 1% THD!
Frequency response is inaudibly flat.
My SNR and DR results met Denon's specs. I had a ground loop [only during digital testing] that I was able to minimize quite well, but not completely eliminate. Nonetheless, even counting the 60Hz I was at their spec using a 20kHz 'brick wall' AES17 filter.
THD vs freq was good, but not exceptional, and ruler flat to about 1kHz.

Audio Performance Summary:
The amplifier far exceeded my expectations. THD was inaudible and SNR was very good as well. A multilayer board could probably allow a PCB that minimizes channel coupling and improve crosstalk and SNR above 10kHz. But if Denon saves any money by using a single layer board then their amplifier performance is good enough to keep me happy.
PURE DIRECT isn't exactly a gimmick but the improvement isn't going to be audible.
On a technical side note, I could see 2SB778 transistors and some 4-pin TO-247/TO-3P/TO-264 devices on the heatsink. I don't know what the 4-pin parts were, but it may have been something like ON Semi's ThermalTrak parts. I could have taken the cover off and found out but I couldn't bring myself to it. I must be getting too old because in the old days I would have cracked the cover without hesitation before I even plugged the thing into the wall...
I wish I could say the same about the digital input as, surprisingly to me, the DACs will constrain performance as the amplifiers have significantly less noise and distortion. Their digital input specs are quite conservative for the 113dB DR rating of the DAC and my results didn't show much headroom in their specs. My guess is that they could spend some additional money on the power supply and decoupling and get much more out of the DACs in the box.

Back at the ranch...:
Build quality seems good. Unfortunately, the receivers are still dominated with linear power supplies. The Audyssey setup worked frighteningly well. One speaker was oddly 1.5 foot off but the rest were within 1 inch of the mic position! I regrettably don't yet have a TV with HDMI so I'm converting video to component for the time being. Component in signals look at good as going directly to the TV; s-video in seems a bit soft. This is just by my eye so don't take this as fact.

All in all, I think Denon hit one out of the ballpark. I'd have liked to see HD upconversion but at the price point they are the obvious choice. CNet gave it an 8.7 and it's clear to me why. Congratulations and thank you Denon!
HT: Sony KV-27FS13 | Oppo DV-981HD | Denon AVR-2807 | 7x Cambridge MC100 | Acoustic Research ARPR1010 || Stereo: Dynaudio Audience 42 | Hales Concept 3 prototypes | wouldn't you like to know... :)

Home PC: Yamaha RP-U100 | B&W LM-1 | Mpyre 65x || Work PC: Yamaha RP-U100 | QSC AD-S32T | Sony MDR-V600

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