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Amp Gurus - Opinions, please..

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  • Amp Gurus - Opinions, please..

    Given these two PCB's, what do you surmise the actual difference is between them? They are rated for the same power, but one is touted as as having better sound due to better components and being 'Hi-Res Audio' capable, which sounds like marketing to me. But the board layout IS slightly different; notice all the extra business happening at the bottom middle. So, generally speaking, do you suppose there could be a discernible difference in sound quality between the two?

    Attached Files

  • #2
    You can't make any decisions on what the sound difference will be based on pictures.

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    • #3
      Originally posted by devnull View Post
      You can't make any decisions on what the sound difference will be based on pictures.
      Yeah. It's even tough given full schematics and test data.
      Francis

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      • #4
        As said.. no way to judge sound quality. But...

        The amp sections look identical. The extra components on the left appear to be small SMT parts and IC's and may indicate more features like processing or DAC and have little or nothing to do with the amp section. I'm guessing these have DAC's built in and some sort of pre-amp?

        I'd also guess the one on the left is the "high res capable", which I would guess as a DAC that handles 24bit 96kHz sampling rates. That might explain the extra parts, but won't really affect overall sound quality. based on images alone, the one on the right appears to be better built with better staking on the parts.
        Electronics engineer, woofer enthusiast, and musician.
        Wogg Music
        Published projects: PPA100 Bass Guitar Amp, ISO El-Cheapo Sub, Indy 8 2.1 powered sub, MicroSat, SuperNova Minimus

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        • #5
          Honestly, Pioneer markets the 'Hi-Res' one through independent dealers and the 'normal one' through chain stores. It gives the independents a couple of more features to talk about to justify the slightly higher price, and they also don't have to price match against the mass movers. Pioneer (and others) have long had slightly modified lines of equipment they market through different channels to try to offer various vendors with targeted products.

          At least until a chain puts in a bulk buy on the DX and blows them out under standard dealer cost, but that is the general reasoning for it.


          The two even share the same owners manual. The only mention of the DX HiRes bit is on the last page

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          • #6
            Pioneer definitely sells the same gear under a different label for different markets. Usually they are the exact same equipment and I don't really care about the 'Hi-Res' label unless there is some physical difference between the two. But seeing that there are some actual differences between the two boards made me wonder. Pricing is about $30 different between the two right now but specs are identical as you point out Dukk - even the S/N ratio and THD. They don't tout any additional features or processing ability (besides gold plated RCA terminals) but it it's an amplifier, not a processor.

            wogg Your observations are interesting to me - I wondered if all that extra business maybe had to do with better input filters or the such. And I was surprised to see the one of the right being better built. They are both digital amplifiers and I recall comparisons on this forum, but mostly other forums, about higher quality digital amplifiers having better filters - like comparing a Crown XLS to an iNuke. I've owned and used both, and find that the Crown subjectively sounds better, IMO, but has a very obvious advantage with power and signal filtering. Just recently, I swapped out an iNuke for a Crown because of a ground loop hum; the crown didn't end up eliminating the loop completely, but it did a much better job filtering it out and dropping the level quite a bit. Could that be what all that extra business is about?

            One other thing I noticed is what appears to be copper plating on some of the chassis/heat sink pieces. Higher-end head units used to tout this feature, as well as high-end AVR's, for "eliminating magnetic induction noise" among other reasons. Whether that is legitimate or just marketing BS, I dunno. Pioneer, Alpine, Eclipse, and I think Kenwood did or still do this to some of their high-end units.

            Oh, and the marker on all of the caps - that's gotta be good for something, right? But for only a $30 price difference, I might have to try it out and compare it to my 96xx series amplifiers.

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            • #7
              Better filtering on a Class D switching amp is referring to the output side rather than input. That's where you need to kill the high frequency PWM switching noise, and would be an improved LC circuit that would involve only a couple of the larger caps and inductors. All those extra SMT bits are definitely not involved in that. I just noticed that I can see the model numbers in the picture file name in Tapatalk, but not on the web forum... odd.

              GM-DX975 vs. GM-D9705
              I scrubbed through the Pioneer manual (same manual for both) and struggled to find anything at all that would justify those extra parts, all specifications are exactly the same. "High Res" compliant means nothing for an amp with analog inputs, like "Digital Ready" that was splattered all over crap in the 80's. Personally, there's no way I'd spend the extra money for the X amp and would be that nobody could ever hear a difference.
              Electronics engineer, woofer enthusiast, and musician.
              Wogg Music
              Published projects: PPA100 Bass Guitar Amp, ISO El-Cheapo Sub, Indy 8 2.1 powered sub, MicroSat, SuperNova Minimus

              Comment


              • #8
                Originally posted by wogg View Post
                Better filtering on a Class D switching amp is referring to the output side rather than input. That's where you need to kill the high frequency PWM switching noise, and would be an improved LC circuit that would involve only a couple of the larger caps and inductors. All those extra SMT bits are definitely not involved in that. I just noticed that I can see the model numbers in the picture file name in Tapatalk, but not on the web forum... odd.

                GM-DX975 vs. GM-D9705
                I scrubbed through the Pioneer manual (same manual for both) and struggled to find anything at all that would justify those extra parts, all specifications are exactly the same. "High Res" compliant means nothing for an amp with analog inputs, like "Digital Ready" that was splattered all over crap in the 80's. Personally, there's no way I'd spend the extra money for the X amp and would be that nobody could ever hear a difference.
                Thanks for setting me straight. I was trying to dust off the mothballs covering what I had read about class d switching filtering in other posts. That’s why I posted the question here

                I will prolly go with the 9705. Or just add the 8601 I have on the shelf to my 8604. Will be running the sub section at 2 ohms and right now the 8604 is running the front comps with the rear channels bridged for a 4 ohm load. The 9705 gets me an additional 100 watts over the 8601 at 2 ohms. I’ve installed the 9705 for folks and was blown away by the sound and power without fading. Some friend use it on their boat with a champion 12 and each section wired to 2 ohms with multiple sets of tower speakers. Of course, they blast it to hear the music when wakeboarding. My experience has been that 5 channel amps weren’t always designed to do max power through all 5 channels and ran out of sauce when you turned it up, but the 9705 didn’t seem to care how loud you pushed it.

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                • #9
                  Do a little more shopping. I think the D9705 can be had for a lot less than the DX975, certainly more than $30 less.

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                  • Blenton
                    Blenton commented
                    Editing a comment
                    Thanks. I happened to be looking at a refurb DX975 thinking it was new, so the price difference is much more than the $30 I thought I was seeing. The D9705 seems to go for ~200.
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