Soo I'm quoting you in hopes of bringing the thread back to life because I need help yet again!
When I tested the speakers through my denon avr1513 I was comparing in stereo direct mode.
In 5.1 the KEFs sound a little veiled and/or dull. Im thinking that this is due to my receiver being old and/or underpowered (rated 75w/channel)
My options at this point are:
1) Go ahead and purchase the costco Yamaha tsr 7810 (I like the extended warranty, peace of mind avoiding refurb, and ease of return) --- then either keep the KEFs or return them and go with the JBLs. The ease of wiring and the ability to sell JBL pretty easily are making me swing to KEF in this scenario.
2) return the KEFs and start all over. Or maybe give up!
Any advice here? The Athenas were 90db sens vs 86 for the Q100s. I suppose it makes sense my receiver can drive them in stereo and they sound good, but it falls way short when in 5.1? I know ratings are difficult to compare on paper and the Yamaha is a higher end receiver (relative to the $99 refurb denon) -- am I correct in assuming this lack of fidelity is an AVR problem? Do you think the Yamaha would be able to drive the Q100s sufficiently?
What DSP mode are you using once running 5ch? It could be a effect of the mode you are using for multichannel playback. If not.......
The output power of a receiver varies greatly when going from 2ch to 5+ channels. Especially cheaper receivers can fall on their face once in multichannel mode. Almost all receivers are power rated with only 2 or some times 1 even, channel driven so when a rating of 75watts is given it will be very different when driving 5 channels. The robustness of the power supply built into the receiver will dictate how much power drops when driving more channels than 2. I would guess a 75watt per channel receiver would only be around 45-50watts per ch when driving 5ch's but a bottom end cheap receiver could be as little as 25-45watts per ch. Depending on your prefered listening volume and your seatting distance from the KEF's in 5ch 30-50watts may not allow clean unveiled playback. Amplifier design is very complex and depending on how the Denon is designed its amplifier's signal to noise ratio could plummet once driving multiple channels also.
You may also want to consider that the quality of the Dac could change once in multichannel. The Digital to Analog converter in budget receivers can have decent specs in 2ch but not so good once in multichannel. All receivers rely on a DSP along with multiple DAC's to convert the digital signal and budget receivers may have a DSP that sounds good in stereo but fall off in specs(signal to noise and dynamic range) and sound quality once in multichannel. DAC's can have very different specs and sound quality in multichannel as well.
If not a DSP mode issue as i mentioned in the beginning I would bet you are experiencing a combination of both an internal amp/power supply that doesnt have the gas and poor multichannel DSP/DAC quality that are adding up to the veiled quality you are hearing once going past 2ch. Budget receivers have indeed gotten much better in a short time because of cheaper quality part cost and manufacturing so upgrading may help with the sound of your setup in all modes stereo included. Power supplies have gotten better in budget gear at keeping power from dropping as drastically as it has been measured to in some older budget gear. ( You can check this by Googling some older Sound and Vision budget receiver reviews and going to the measurment section at the end of the reviews where power is measured and look at the power in 2ch and then in 5 or 7ch. Then go to some of the more recent budget receiver reviews and look at the same measurments. The same can be done for the DAC's and DSP's even if they are not measured you can find out which are used in the DUT and look up the specs at the manufacturer's site. Its easy to see that budget gear is built with better spec'ed parts today then 5 years ago. )
Also any newer receiver will probably have room correction built in that will drastically help how your speakers interact with your room in frequency response and in the time domain(aka ringing).
You could very well have a different problem than I outline here but when I see that you are using a $99 Denon(even referb this is quite budget) these are the first things that come to mind that could be the cause.
Good luck with solving the issue and consider a receiver upgrade from a retailer with a hassle free return policy and if the new kit doesn't solve your issue you can always return it, though it may also bring a new level of sound quality all around you can't do without if it has room correction on board.
Edit: Just saw the recommend for the Denon X3300 and I would strongly consider it, as XT32 is far more advanced than the Multi Eq in the Marantz 5011. I love my Marantz but with your budget I would go for the Denon with the XT32. Either will likely be a solid sound upgraded over your current Denon but XT32 can implement 32x the filters of regular Multi eq with far greater resolution. Also the x3300w will get you the new Audyssey app which is key to getting the very best performance from Audy and will allow you to dial in just about any response you like. The app gives you full control over the process where without the app you are stuck running the correction over and over and hope you get the sound you want on one of the runs. Also Audioholics found the x3300w to maintain great power numbers(true 75watts per ch. 5ch. driven) when powering 5ch's and easily beat the pants off the Yamaha(37watts per ch.5ch. driven) they tested it against.
Keep in mind most review publications don't do continuous power measurements and they usually publish power measurements into clipping at 1% THD + N. Our measurements are very conservative as we use a dedicated 20A line with no Variac to regulate line voltage. We constantly monitor the line to ensure it never drops more than 2Vrms from nominal, which in our case was 120Vrms.
For more info on amplifier measurements, see: The All Channels Driven (ACD) Test
# of CH Test Type Power Load THD + N
2 CFP-BW 100 watts 8-ohms 0.1%
2 1kHz Psweep 132 watts 8-ohms 1%
2 1kHz Psweep 127 watts 8-ohms 0.1%
1 1kHz Psweep 182 watts 4-ohms 1%
1 1kHz Psweep 163 watts 4-ohms 0.1%
5 1kHz Psweep 37 watts 8-ohms 1%
5 1kHz Psweep 35 watts 8-ohms 0.1%
1 Dynamic PWR 174 watts 8-ohms 1%
2 Dynamic PWR 255 watts 4-ohms 1%
5 Dynamic PWR 139 watts 8-ohms 1%
Yamaha RX-A860 Power Measurement Table
# of CH Test Type Power Load THD + N
2 CFP-BW *105 watts 8-ohms 0.1%
2 CFP-BW 154 watts 4-ohms 0.1%
1 1kHz Psweep 160 watts 8-ohms 1%
1 1kHz Psweep 140 watts 8-ohms 0.1%
1 1kHz Psweep 237 watts 4-ohms 1%
1 1kHz Psweep 218 watts 4-ohms 0.1%
2 1kHz Psweep 132 watts 8-ohms 1%
2 1kHz Psweep 119 watts 8-ohms 0.1%
2 1kHz Psweep 180 watts 4-ohms 1%
2 1kHz Psweep 165 watts 4-ohms 0.1%
5 1kHz Psweep 88.6 watts 8-ohms 1%
5 1kHz Psweep 76.4 watts 8-ohms 0.1%
1 Dynamic PWR 206 watts 8-ohms 1%
1 Dynamic PWR 322 watts 4-ohms 1%
2 Dynamic PWR 277 watts 4-ohms 1%
5 Dynamic PWR 145 watts 8-ohms 1%
Denon AVR-X3300W Power Measurement Table
* only if Eco mode turned off. Sometimes the internal limiter tripped and reduced power to 85 watts/ch on the bench.
The Denon AVR-X3300W handedly outperformed the Yamaha RX-A860, but to Yamaha's defense, the RX-A860 retails for $100 less, which makes a world of difference in low-margin high-volume mass produced products like this. I do think most of the power differences between these two products have more to do with Yamaha's excessive nanny controls to protect the amp than the Denon actually having that much bigger of a power supply.
The AVR-X3300W offered respectable output into 8 ohm and 4 ohm loads. At times, their limiter circuit did interfere with my bench tests, even when Eco mode was turned off. I'm not sure it if was overly touchy or if it was an intermittent software glitch but I did inform Denon about this.
That said, > 80 watts/ch with 5 channels driven is quite respectable for a "does everything" Atmos/DTS:X receiver at this price point.
With just two channels driven, the AVR-X3300W produced impressive 1kHz power tests that exceeded its 105 watts/ch rating. With five channels driven, the Denon held up pretty well delivering 88 watts/ch (1% THD+N) with 5 channels driven.
Unlike the Yamaha RX-A860, which just didn't behave well with 4 ohm loads, the Denon AVR-X3300W didn't have a problem. It was able to output almost 180 watts/ch with 2 channels driven at 1% THD+N.
The AVR-X3300W performed well for CEA 2006 short dynamic burst tests that didn't trip the internal current limiting circuits. It was able to muster over 200 watts/ch into 8-ohm loads and over 300 watts/ch into 4-ohm loads. The AVR-X3300W offered very respectable continuous and dynamic power reserves for its product/price category.
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