Receiver vs. amp: was this a valid test?

Discussion in 'Archived Threads 2001-2004' started by Paul Clarke, Jun 9, 2002.

  1. Paul Clarke

    Paul Clarke Supporting Actor

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    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
     
  2. Milt S

    Milt S Auditioning

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    I don't think your test is valid.

    Everything I've read about A-B testing states that if one configuration is playing louder, it will be preferred by the listener. Your test merely validates this.

    Instead of setting both volume controls at the same level, I believe you should set the controls so that both configurations produce the same SPL. Then you can evaluate which amp sounds better to you (assuming the 310 and 510 preamp sections are identical).

    Speaking of which ... you state that the innards of the 310 and 510 are the same (other than power and HDCD); are you sure about this? IMO, the only really fair way to do this is to use the 510 only and compare the output of the 510 amps with the outboard amp you're evaluating (at the same SPL level).
     
  3. Paul Clarke

    Paul Clarke Supporting Actor

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    Hello Milt,
    Thanks for the input. I posted this on the AVS forum as well and got some replies similar to yours....soooooo---
    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. And you never know what any particular receiver/amp combo will yield until you wire it up.[​IMG]
     
  4. Chu Gai

    Chu Gai Lead Actor

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    I'm a bit confused by your post and perhaps its on my part. You're using the same speakers yes? If this is the case, you don't level match using an SPL. The typical home SPL is rather crude and you'd have to find a way to mount it such that it never ever moved or deviated from its position.
    Instead, in the interests of keeping it simple what you do is take your 1kHz tone and measure the output at the end of the speaker wire with a VOM. Now set the second combo up and adjust the level to read the same or as close as you can get it. Now perform your test and if what you're REALLY looking for is to make an assessment as to whether there are sonic differences and to determine a preference, have a friend do the swithing with a coin toss. You sit back with a blindfold on and a glass of something non-alcoholic! Have your friend switch back and forth according to the coin toss about 10x...So now what did you pick?
     
  5. Paul Clarke

    Paul Clarke Supporting Actor

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    Thanks Chu,

    Actually I was using the Radio Shack Analog meter mounted on a tripod at a stationary position with a 45* or so upward tilt.

    I was trying to check out both power and sound quality differences. I expected the 310/855A combo to outperform the 510 in terms of power even though the amp and 510 are very close in ratings. But I didn't expect to find an audible difference when using both H/K's as pre/pros with the amp. However, I did prefer the 310/855A setup just ever so slightly, even without the HDCD decoding advantage of the 510. I attribute the small Spl increase on same source material to variances in the pre-amp output staging of the 310. Another 510 might have had greater output or another 310 might have had less.
     
  6. Chu Gai

    Chu Gai Lead Actor

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    Well even with your mounting of the SPL on the tripod, the best method is to check the signal at the speaker terminals with a VOM. It is preferred to level match at 3 frequencies. This is done to compensate for various differences that may exist between units. I suggested the one at 1kHz but that was largely done to try and keep it simple for you. Inexpensive ones are out there, even at Radio Shack and with the 4th sales coming up, you might be able to obtain one inexpensively priced. You'll find the VOM to be a useful tool just to have around the home. But that's your call. Again this does imply using the same speakers and all. Its really the only way to ensure that both setups are driving the speakers with the same power.
    While others may take issue with the inclusion of blind testing, its a valuable tool in weeding out numerous biases, most, if not all, of which we can't control. Yes it does take a bit of the mystery out of the equation, but it really depends on what one's questions are that they're trying to answer and the degree to which they want an answer. It does involve the use of friends and does provide for a bit of fun and socialization as well exposing oneself to a bit of science in the application of audio. Your call though. I'm sure you'll make a good choice
     
  7. Paul Clarke

    Paul Clarke Supporting Actor

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    I agree with you on the voltmeter. It's one of those things I've needed to have around the house and never picked one up.

    Also the blind testing is the only real way to put these things to rest. But in this case my demands are not that severe or strict.

    I simply have two companion H/K's of different model number but same series. I was thoroughly impressed with the 310 bought in a private sale...it is flawless in appearance and used by the previous owner as a pre/pro with PA5800 amp. The 510 (actually my second) was bought a short time later off Ubid. You know, one of those 'hedge your bets' kind of thing. I didn't know Ubid would be handling the 855A closeout...and so soon after the 510 purchase.

    1)The 510 advantage of component plugs (15MHz) is good only out to 480i, possibly 480p so not much there.
    2)The added amp power is now a non-issue with the Parasound.
    3)The HDCD decoding is great to have but can be found in source players if needed. Also, my listening tests as stated found a slight preference for the same source material without the HDCD 'advantage'.
    4)There is also a front video input/output conversion option with the 510 which is nice but not essential.
    5)Lastly and a big consideration, there is the warranty with the 510 which I do not have with the 310.

    I forgot to include in my last post that I had run frequency signals from my CD test disc and made comparisons. I highly suspect that the result variances between receivers simply in terms of output would be traceable to the inefficiences employed in my calibrations, such is the consistency of H/K processing.

    Many thanks for your continued input.

    Paul
     
  8. Chu Gai

    Chu Gai Lead Actor

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    did you get hammered on s/h from ubid? for myself i've found that to be just a 'bit' steep at times. enjoy your system and may you never need warranty!
     
  9. Paul Clarke

    Paul Clarke Supporting Actor

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    Thanks again Chu. Here's a copy of a post of mine from the AVS Forum dealing with a Ubid Thread:


    "Nothing but good luck so far.

    First order in Feb.---pair of Wharfedale Emerald 97 towers (new)
    Second order in March---Test CD Lasertrak 2000 (new)
    Third order in April---H/K 510 (refurb)
    Fourth order in May---2nd pair of Wharfedale 97's (new)
    Fifth order in June---Parasound 855A amp (new)

    S/H is too high but all of mine came within a week even though the info on My Page was well behind real time. I could only track about half of the orders. Only the 510 was single boxed but still well packed.

    Any problems I have had with Ubid have to do with the obvious bidding shenanigans that go on from time to time on certain auctions.

    I use the Ubid credit account and generally get the 90 days same as cash deal and the S/H discount. Sooner or later though the 'Luck' will run out so I'm saying bye to Ubid for awhile."


    Even though they do hammer you on the S/H, the savings are still incredible...even on B-Stock and reduced price (for whatever reason) merchandise. I figure the $ saved after the S/H still puts me WAY AHEAD.
     

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