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Thread: Crown clean enuf for HT?

  1. #16
    Senior Member just4kinks's Avatar
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    Quote Originally Posted by Mr. Widget View Post
    I may be wrong, but I believe that the opinion I stated which I fully agree with is held by the vast majority of seasoned audiophiles and audio professionals. Beyond that, I am unaware of any study where a correlation between better sounding amps and lower THD has been made. Then again, I can think of one prominent "expert" who claimed to his death that he couldn't hear a difference between properly functioning high quality power amps.

    Well, people have been arguing about this for a long time. My understanding is that it comes down to a basic question: What do you want from an amplifier? Do you want sonic accuracy, or do you want something that sounds good?

    THD is a measurement of how closely the output signal resembles the input signal. If you want sonic accuracy, THD is an excellent measurement. The problem with THD is that it measures both good distortion and bad distortion. Tube amps will add a little good distortion to get that classic "warmth" that people love about tubes. If you want an amp that just sounds good, and you don't care if the sound is colored a little bit, then THD is a useless measurement -- because it doesn't differentiate between the good distortion and bad.

    IMO, I think an amp should be sonically accurate. I think that all effects and coloring should be done in the recording studio. I buy amps with low THD. Maybe I'm missing out on something, and maybe one day I'll change my mind and try the tube thing.

    Now, to get back to the thread... AFAIK, solid state amps do not produce much good distortion, and the only time THD is a good thing is with tube amps. The thread starter is asking about a solid-state PA amp, and I would think that 0.5% THD is going to sound awful.


    BTW... most of my perspective on this comes from reading solid-state amp books, particularly Douglas Self's "Audio Power Amplifier Design Handbook". Maybe my perspective will change when I get around to reading some audiophile / tube-amp books.

  2. #17
    Administrator Mr. Widget's Avatar
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    Quote Originally Posted by just4kinks View Post
    IMO, I think an amp should be sonically accurate. I think that all effects and coloring should be done in the recording studio.
    I agree. I would go as far as to say that there is no "good" distortion.

    That said, I disagree about the relevance of THD specifications. Many amps with super low THD specs sound hard and glaring. I would submit that THD is a red herring number. There are differences in amplifier's sonic qualities and I do not think that a THD spec will tell you much. For one thing, THD like impedance isn't a static number. An amp that has 0.5% THD as it's spec may be one with very low THD up to a dB or two of it's rated power but the marketing department of the manufacturer wanted to call it a 200wpc amp instead of a 150wpc amp so he rides up the distortion curve a bit. The same amp sold as a 150wpc amp may have a THD spec of 0.05.


    Widget

  3. #18
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    Mr Widget:
    In 40 years or so of this hobbie, I would agree with the view that product marketing has a lot to do with power ratings.

    Example: I have two HT receivers: a Denon w/100 WPS and a Onyko w 130 WPS. Without measuring output, I would guess the Denon has twice the power as the Onkyo. I assume this has to do with power ratings in relation to THD; right? Both amps are rated at .05% THD.

    ...anyway, so does the SPL impact sound quality too? My HT is played at a very low SPLs....

    ...if you had an amp with a realatively high THD rating, would it sound crappie at all SPLs or only at higher volumes?

    Thx..

  4. #19
    Administrator Mr. Widget's Avatar
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    Quote Originally Posted by robertbartsch View Post
    Example: I have two HT receivers: a Denon w/100 WPS and a Onyko w 130 WPS. Without measuring output, I would guess the Denon has twice the power as the Onkyo. I assume this has to do with power ratings in relation to THD; right? Both amps are rated at .05% THD.
    I doubt it has to do with THD, but it might. There are so may other variables here.

    For one thing, you say you'd guess it has twice the power. In many cases the compressed lower powered higher distortion system will seem subjectively louder.

    Are the two receivers about the same vintage?

    Quote Originally Posted by robertbartsch View Post
    ...if you had an amp with a realatively high THD rating, would it sound crappie at all SPLs or only at higher volumes?
    Again... too many other variables to give a clear cut answer.



    Widget

  5. #20
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    One other observation. I recently bought a 500 watt "D" type amp for an 18 inch JBL sub-woofer. The amp is very light weight without any heavy transformer necessary. It also runs cool and has NO vents in the cabinet.

    Anyway, this amp produces very clean low frequency sound. I like it very much. I assume recreating HF sound is more diffucult with a D type amp, however; right?

  6. #21
    Senior Member just4kinks's Avatar
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    Quote Originally Posted by Mr. Widget View Post
    I agree. I would go as far as to say that there is no "good" distortion.

    That said, I disagree about the relevance of THD specifications. Many amps with super low THD specs sound hard and glaring. I would submit that THD is a red herring number. There are differences in amplifier's sonic qualities and I do not think that a THD spec will tell you much. For one thing, THD like impedance isn't a static number. An amp that has 0.5% THD as it's spec may be one with very low THD up to a dB or two of it's rated power but the marketing department of the manufacturer wanted to call it a 200wpc amp instead of a 150wpc amp so he rides up the distortion curve a bit. The same amp sold as a 150wpc amp may have a THD spec of 0.05.


    Widget
    That's a very good point. Who cares about THD at rated power if you do most of your listening at 1 watt? You've given me something to think about.

    Another problem that I'm aware of is that some manufacturers only publish THD at 1kHz. THD generally increases with frequency, so a THD spec is incomplete unless it is made over the entire frequency range. For example, the spec on my D-75 is:
    "Total Harmonic Distortion (THD): Less than 0.001% from 20 Hz to 400 Hz and increasing linearly to 0.05% at 20 kHz delivering rated power into 8 ohms/channel."

  7. #22
    Senior Member BMWCCA's Avatar
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    Quote Originally Posted by robertbartsch View Post
    One other observation. I recently bought a 500 watt "D" type amp for an 18 inch JBL sub-woofer. The amp is very light weight without any heavy transformer necessary. It also runs cool and has NO vents in the cabinet.

    Anyway, this amp produces very clean low frequency sound. I like it very much. I assume recreating HF sound is more diffucult with a D type amp, however; right?
    The DC300A-II is rated about 545 to 600-watts @ 8ohms, bridged, depending on range, THD, criteria used, etc. That's as powerful a D-series amp as they ever made. The D150A-II is 315 watts. I don't know if you were referring to High Frequency (HF) sound or High Fidelity, but the Crown D-series amps have no problem covering the entire audible range and many here use them in their home hi-fi systems. Just ask my 075s that have had nothing but Crown power through them since 1974 (D150, D150A-II, DC300A-II). The PS-series is really just a slightly updated D-series. The PS-400 is rated at 660W bridged, still with no fan, and it makes my L7s sing, too.

  8. #23
    Senior Member just4kinks's Avatar
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    Quote Originally Posted by BMWCCA View Post
    The DC300A-II is rated about 545 to 600-watts @ 8ohms, bridged, depending on range, THD, criteria used, etc. That's as powerful a D-series amp as they ever made. The D150A-II is 315 watts. I don't know if you were referring to High Frequency (HF) sound or High Fidelity, but the Crown D-series amps have no problem covering the entire audible range and many here use them in their home hi-fi systems. Just ask my 075s that have had nothing but Crown power through them since 1974 (D150, D150A-II, DC300A-II). The PS-series is really just a slightly updated D-series. The PS-400 is rated at 660W bridged, still with no fan, and it makes my L7s sing, too.

    I think he's referring to Class-D amps, not D-series.

    Robertbartsch, you're right on about class-D amps. Efficient, powerful, cool, great for subs. I've heard that the modern high-end ones are good for high frequencies too.

    You might be interested in Crown Class-I amps also.

  9. #24
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    Quote Originally Posted by just4kinks View Post
    I would not even consider it for home theater, for the simple reason that it is fan-cooled. Fan noise really gets on my nerves when I'm trying to enjoy music / theater.
    I recall Widget making a similar comment about fans.

    If you put your amps in the same room that you listen in, then that is a possible concern. Nevertheless, there are many very, very quiet amps that have fans that are below my threshold of hearing, though my Hafler SR2300 and 2600 amps will make a barely audible sound during a quiet passage after being played hard for a while.

    But I like fans. Amps with fans run cooler, and when you put those beefy components inside a metal container, heat will accumulate. Yes, fins and vents will alleviate some of the trapped heat, but only a fan (or fans) will both draw out more heat and cool down heat-producing components. these are both big plusses to me.

    The easy fix for me is to do one of two things: put the amps in a separate room or closet, or put the amps in a hush box enclosure. I've done both.

    TBT, in my current music room set up, I have three Haflers sitting in the rack looking for all the world like they're the iron that drives the two channel systems, but in reality I've some more Haflers sitting behind the wall that actually drive everything. All the minor fan noise and heat is two sheets of drywall, a 2x6, and 5" of insulation away.

    My JBL Performance Series AVA-7 amp sits right in the HT, though it has two fans. I've never, ever heard them, even in the quietest moments.
    In.

  10. #25
    Senior Member BMWCCA's Avatar
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    Quote Originally Posted by just4kinks View Post
    I think he's referring to Class-D amps, not D-series.
    Oops! You're probably right. Threads are jumping around quite a bit lately. In the words of Emily Litella, "Never mind".

  11. #26
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    The THD bugaboo

    I think I agree with Widget in the relative unimportance of THD specs. (He'll tell me if I don't.)

    It's widely accepted that we can't perceive THD below 1%.

    If someone will write that he or she has exceptional hearing, that God or the great immutable Eternal or evolution gave him or her the blessing of auditory sensitivity above that of mere mortals, then boffo for you! Rather than challenge you to prove it, I'll just say count your blessings, but don't rub it in.

    The average listener will never hear the difference between 0.1% and 0.01% or 0.00005%.

    Let's also add that the distortion in a system is only as good as its worst bit or a combination thereof.
    In.

  12. #27
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    This thread is proving to be very interesting and useful; Thanks all!

    Anyway; Hey Ti Dome:

    If variations in THD below .1% are not determinable by mere human ears and gray matter, why do you suppose (more??), Hi-Fi (HT??) manufacturors don't use Class D amps in their multi-channel systems?

    I assume this would allow them to avoid heavy and expensive power transformers and caps; right?

    A few decades ago there was a "new" amp design called the Carver. I don't remember much now, but I thought it was based on a design that did not need heavy transformers or big caps. Was this the first Class D?

    Thanks ALL!

  13. #28
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    Crown 802 specs

    These are the specs of the new Crown 802D amps:




    Specifications

    Sensitivity (volts RMS) for full rated power at
    4 ohms
    1.25
    Frequency Response (at 1 watt, 22 Hz - 20 kHz)
    +0 dB, –1 dB
    Signal to Noise Ratio below rated power (20 Hz to
    20 kHz, inputs terminated)
    A-weighted, below rated power
    No weighting, below rated power
    > 100 dB
    > 95 dB
    Total Harmonic Distortion (THD) at 1 full bandwidth power, from 20 Hz to 1 kHz
    < 0.5%
    Intermodulation Distortion (IMD) 60 Hz and 7 kHz at 4:1, from full rated output to –30 dB
    < 0.3%
    Damping Factor (8 ohm): 10 Hz to 400 Hz
    > 200
    Crosstalk (below rated power)
    at 1 kHz
    at 20 kHz
    –75 dB
    –50 dB
    Input Impedance (nominal) (balanced,
    unbalanced)
    20 kilohms, 10 kilohms
    Load impedance
    Stereo
    Bridge mono
    4-8 ohms
    8 ohms
    AC Line Voltage and Frequency Configurations Available (± 10%)
    120 VAC 60 Hz
    Ventilation
    Flow-through ventilation from front to back
    Cooling
    Internal heat sinks with forced-air cooling
    Air Volume Requirements (per minute
    per unit)
    80.15 ft3 (2.27 m3)
    Dimensions: Width, Height, Depth
    XLS 802: EIA Standard 19"W (EIA RS-310-B) x 3.5” (8.9 cm) H x15.2" (38.6cm) D.
    Net Weight, Shipping Weight

    XLS 802: 35.5 lb (16.1 kg), 40.5 lb (18.4 kg)

  14. #29
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    For those of you who view THD as important or somewhat important, the Crown 802D is rated at 500 wpc x 2 into 8 ohm loads. The price new w/ 3 year warranty is around $500-600 USD.

    The THD rating below is .5% THD from 22hk to 1Khz (????).

    I have no idea why they would give this rating unless the amp was intended only for the low frequency in a bi-amp system, I suppose.

    I have seen other Crown ratings of this same unit of .1% from 22hk to 20Khz, however.

    ...So we have some more confusion on THD ratings, I suppose.

    Thanks....

  15. #30
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    If I hear or read one more person referring to a Steely Dan or Donald Fagen recording to use it as a standard of excellence I'm gonna puke.....I like them as much as the next guy, but if you heard a mixer walk in and put in a Steely Dan CD to judge the quality of the system as many times as I have, you'd understand....

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