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Discussion Starter · #1 ·
Here's the setup:


(Only Stereo tested)

H/K 510 in main system with 2 Wharfedale Emerald 97 towers


H/K 310 as pre/pro with Parasound 855A and 2 Wharfedale 97's


Channel levels were at 0 on both H/K's and volumes at -25

Gain was maxed on the amp


Test tone at 1kHz showed a 5+dB increase for the 310/amp

Other test tones also yielded anywhere from 2.5-4dB increase for the duo.


Same passage music content yielded 2-3dB increase on avg.


Question?...Can I expect the 310 as a pre/pro to approximate

the 510? I just didn't feel like tearing everything down so I could add in the 855 to the 510 which is my ultimate aim. Both H/K's have the same innards and feature set differs only in HDCD decoding (which wasn't utilized in testing) and extra watts for the 510. Since the power rating of the 510 and 855 is very similar, I wanted to see if there would be a significant difference. Considering the 855 is brand new out of the box with no break-in, I found the sound change to be quite apparent and certainly the Spl's bear out the power difference.


Any opinions...insights? TIA
 

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2-3 db difference is a ton. Need to get closer to eval sound quality.
 

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Remember that a 3dB difference is equivalent to doubling the amplifier power.

Your differences in sound level are more likely to be due to either the output voltage levels of the preamp outputs of the 310 or the input sensitivity of the amplifier. The zero point on the volume knobs are arbitrary and don't necessarily mean the same thing on different models.


As bpape indicated, when you're listening for quality differences you have to carefully calibrate the volume levels so that the same source input produces the same sound pressure level to a fraction of a dB. Small volume differences are easily mistaken for quality differences.


That said, I'm not at all surprised that using the Parasound amp would produce a noticably improved sound. The HK spec pages carefully omit the critical phrase "all channels driven" and rate the different channels individually. This means that neither receiver can supply the rated power to all speakers simultaneously. The lower THD ratings and the total power requirements in the Parasound specs seem to suggest that more power is available, althgouh they also don't explicity state that their ratings are for all channels driven simultaneously.
 

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Discussion Starter · #4 ·
Thanks guys, I understand about the need for tighter controls on the evaluation setups. This first one was a preliminary test but I will do further, stricter testing in the future. I'm going to sell one of these receivers in the near future so I'm more interested in finding the one with the superior sound processing quality to keep.
 

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Discussion Starter · #5 ·
Follow-up testing info for anyone who's interested:


Used Avia to adjust channels for both receivers at -20 volume setting.


H/K 510 w/o 855A...Front L=+10...Front R=+7

H/K 310 w/ 855A...Front L=+5.....Front R=+4

Not concerned at present with other channel levels although multi-channel stereo will become a more important consideration.


Checked output at the following volume levels:


-20 volume (yielding 70dB) & -15 volume (yielding 75dB)

-10 volume (yielding 80dB) & -5 volume (yielding 85dB)

No more than .25-.50dB variance between receivers at any volume setting after calibration.


Sound quality checks at this point yielded the following:


510 on it's own sounded slightly harsh, treble slightly brittle, bass punchy but less refined. I believe the lack of the high damping factor of the 855A may be in evidence here.


310 w/855A slightly smoother, more delicacy and subtlety, tight, refined bass. Also slightly greater Spl output on same critical test passage/note selections.


Next phase was to determine any differences in sound quality with both receivers getting external amping.


Used the same speaker set connected to the 855A...switched the pre-amp interconnects between the receivers back and forth.


Sound quality judgements still favor the 310 as pre/pro but only ever so slightly. Surprised to see a small advantage in output on same source material/passages still favoring the 310/855A combo. Even on material with HDCD and the 510/855A, the same material without the HDCD had slightly more output and dynamics with the 310/855A.


Conclusions thus far:


I'm gratified to see the consistency in amp staging and sound processing in the H/K line. Previous tests of these two receivers using only their own amps found, as expected, no more than a 1.25-1.5dB difference in output and very similar sonic character. In the final analysis though, there really is no substitute for quality external amping. :D
 
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