The Truth About Digital (Class D) Amplifiers

Discussion in 'Amps, Pre-Pros & Receivers' started by ruadmaa, Jun 17, 2006.

  1. ruadmaa Banned

    ruadmaa
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    I have read the above audioholics article and, quite frankly, it doesn't make a whole bunch of sense. I have directly compared a Panasonic Digital XR-55 with a Yamaha RX-V1400 for almost a month and could not tell one bit of difference in audio quality. The Audioholics article made a digital amp sound like it was nothing but garbage. My ears certainly don't tell me that.
  2. silversurfer Senior Audioholic

    silversurfer
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  3. mike c Audioholic Warlord

    mike c
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    http://www.audioholics.com/techtips/audioprinciples/amplifiers/classDamplifiers.php

    it was written by some guy from Philips. maybe he wasn't "in" on the b&o icepower crowd :)

    A lot of people hate the harman DPR receivers. perhaps it was just psychological, or it could just be the poor design of the DPR units.

    I don't notice a difference with my class d amp. Just like what was mentioned in the article: class d is going to take over very very soon.
  4. silversurfer Senior Audioholic

    silversurfer
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    The Hypex UcD amps by Bruno Putzeys are suppose to be very good too.

    I notice you use Rotel amps, they are using an ICEpower module in their new class D amps.
  5. mike c Audioholic Warlord

    mike c
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    yup ... there's quite a lot of discussion about class D rotel amps at htguide.coom
    -one of the reasons I considered the 1077
  6. silversurfer Senior Audioholic

    silversurfer
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    How do you like the 1077? What other amps can you compare it too?
  7. mike c Audioholic Warlord

    mike c
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    I can only compare it with the Rotel RMB1066 bridged to 150wpc x 3.
    I can hear NO difference, except that I miss the "louder" 1066. (watts is watts ... the more the merrier)

    I like and chose the 1077 for both space and heat concerns. I only have space under the TV, and to even fit a 100 x 5 amp + a dvd player would be impossible.

    I haven't given the amp a thorough music test (especially with my more demanding r&b music) I will post back after I put the test CD in.
  8. silversurfer Senior Audioholic

    silversurfer
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    Thanks Mike!
  9. mike c Audioholic Warlord

    mike c
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    silversurfer,

    while the test conditions are NOT the same ... I have finally listened to the 1077 using the same material. (I added curtains and couches since the last time I compared a yammy 640, rotel 1066 and an HK3480)

    results: 100wpc of the 1077 simply cannot boom the bass on my tower speakers. the 1066, did a better job of giving excursion to the bass drivers.
    the 1066 is rated at 150wpc x 3. but when I tested it, I only used 2 channels ... I'm guessing, that added more headroom to the amp.

    I bi-amped the towers using 4 channels of the 1077 and tested again with the same material, this time there is driver excursion, but it barely gave me the chest thump (most probably attributed to the room changes).

    don't get me wrong, the 1077 is a pretty good amp ... it achieves what it was designed to do, which is to give 100wpc or more x 7 in a small package, lighter unit and "cooler" running amp.
  10. silversurfer Senior Audioholic

    silversurfer
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    Very interesting Mike. Thank you.

    How did the mids and highs sound?
  11. Sleestack Senior Audioholic

    Sleestack
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    The problem with that article is that it makes sweeping assertions based on a very few product samples. Also, the article seems to talk more about interference issues than sound quality issues. I converted to all digital amps in both my HT and 2.2. channel systems. I use the TACT BOZ216/2200s to bi-map and externally crossover each of my Andra IIs. I definitely prefer the TACT setup over the Parasound A51 and Meridian G57 I was using and really seee no reason to ever go back to SS or tube amps.
  12. jaxvon Audioholic Ninja

    jaxvon
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    One of the consultants, Bruno Putzeys (I believe I spelled that correctly), does work for Phillips. He seems to have a bias against TACT and their design, basically calling their high output-DAC design junk (though I have never seen any justification for his claim). Obviously not all digital amps are good, and sadly many are crap. But like Sleestack mentioned, sweeping generalizations can give false information on what's actually available and possible.
    Last edited: Jun 26, 2006
  13. mike c Audioholic Warlord

    mike c
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    silversurfer, as much as I have read a LOT of comments that the mids and highs of this amp is much improved over the analog offerings of Rotel double the wattage (one of the reasons I bought it) ...
    I can only imagine because I simply cannot remember the difference.
    I am afraid to conclude because it could simply be my weak memory or imagination of hearing "new" things.
  14. Sleestack Senior Audioholic

    Sleestack
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    I would like to hear what he has to say about it, however, if he's talking about the audible qualities of their amps, he's either smoking crack or has an agenda. Nevertheless, the room correction is why primarily why I use TACT. The 216/220 amps are great, but versatility is their differentiating strength. Other than that, they just sound like clean amps. You could easily get more power using a SS setup if you didn't need the versatility of the amps. I have no comment on the other TACT amps b/c I have no experience with them. If radio interference is his primary issue, it really is a non-issue for me.
    Last edited: Jun 26, 2006
  15. jaxvon Audioholic Ninja

    jaxvon
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    I'll try to get a quote tomorrow. I have access to a lot of journals via UofM, but I can't access them from home. When I'm at the U tomorrow I'll try to pull up the article I read.
  16. silversurfer Senior Audioholic

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    That is very fair of you. Thanks.
  17. Sleestack Senior Audioholic

    Sleestack
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    Thanks. The other consideration is that he may have been commenting on their older amps, which were designed back in the late 90s. TACT is on a new generation of amps which have a different design. The older amps were a single box design with 150w ouput at 8 ohms. The new 2200 amps, shown on the right below, utilize the external 216 power/control center and a new floating point DSP engine, and have 200w output at 8 ohms.

    [​IMG]
    Last edited: Jun 26, 2006
  18. jaxvon Audioholic Ninja

    jaxvon
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    Here's what Bruno had to say regarding digitally controlled amps like the Tact:

    I read this article in a journal, though what I have posted (and more) is available on Bryston's website. Here's the link:

    http://www.bryston.ca/newsletters/74_files/vol7is4.html
  19. gene Audioholics Master Chief Administrator

    gene
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    You can drive two different cars on a highway at 60mph and not notice much of a difference until you are faced with external influences such as weather conditions, road obstacles requiring quick maneuvers that the inferior car may not be up to task to handle.

    My point is, alot of it depends on load conditions, quality of source material played back, quality of listening space, quality of speakers, discernability of your ears.

    I personally purchased the older version of the Panasonic Class D receiver b/c I felt the amp section was so bad that it was a worthy piece of gear to add to my reference system for comparative purposes. I will be referencing this in up and coming listening tests once the primary theater room in the Showcase home is completed.

    This article is NOT a knock on Class D amps as much as it is a reminder that there are technical hurdles manufacturers must jump in order to design them properly.

    See our Article: Switching Amps: Technology & Issues

    There is no such thing as a "Digital" amp really. All amps are analog in nature but some such as class D amps are Switchers.
    gene,
  20. gene Audioholics Master Chief Administrator

    gene
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    Actually he no longer works for Phillips. I don't recall him ever stating that their design DAC is junk and he gives good reasons as to why that type of method is NOT optimal.

    Yes I agree which is why its important to NOT put words in peoples mouths or misquote them when they write articles :rolleyes:
    gene,

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