Crown CDi1000 Power Amp Review and Measurements - Stream of Consciousness

Discussion in 'Power Amps' started by purr1n, Jan 12, 2020.

  1. purr1n

    purr1n Finding his inner redneck

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    I should add, the stuff in the tin cans tends to sound better. Old wives tale I've heard from DIYers and old audio gear designers - the ones who can do discrete designs.
     
  2. Armaegis

    Armaegis Friend

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    I thought that had something to do with either thermal or electrical stability? I vaguely remember reading something where the larger size and mass made it less susceptible to tiny wiggles in temperature and electrical voodoo.
     
  3. purr1n

    purr1n Finding his inner redneck

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    Maybe vibrations too, as evidenced by the vibrations and singing at higher wattage levels. There's so much we don't fully understand and haven't explored yet.
     
  4. Armaegis

    Armaegis Friend

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    Singing? As in you can hear the metal caps vibrating? I've heard transformers modulate and coils whine before, but not chips.
     
  5. purr1n

    purr1n Finding his inner redneck

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    Not sure what parts. It's probably a combination of everything, the resistors, traces on the boards, caps, transistors. Metal vibrates when current passes through it. Like the old 50s homes with aluminum wire. And we are talking about a hundreds of watts here.
     
  6. schiit

    schiit SchiitHead

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    Oh, you can definitely hear the output transistors singing when you're doing resistive load testing. If you're playing music through a speaker, you'll never hear it, but running test tones (or music) into a resistor--oh yeah, and it gets pretty loud. Especially the metal cans. But hell, you can hear it on plastic packs too, both the big TO-247s and the smaller PCB-mounted stuff. Vidar, Aegir, and Jotunheim R all sing.

    What causes it? Rapid thermal expansion and contraction of the package. Yes, they expand and contract enough to produce sound. Yes, this phenomenon can also extend to output resistors (really crappy ones, usually.) Thermal modulation is a real thing, and it needs to be taken into account if you get enough heating on critical parts (say, like the feedback resistor of a current feedback amp, which usually runs quite a bit of current).

    I was tripped out when I first heard it at Sumo. I forgot about it until we introduced Vidar and I was doing resistor load testing, and the amp was making this weird whining noise...I realized what it was, and had a good laugh.

    Sorry for the additional derail, but you were talking about singing transistors...to contribute, the amp in question looks like a Class G (rail riding) or Class H (rail switching) design, with a switchmode power supply, rather than Class D.
     
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  7. Armaegis

    Armaegis Friend

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    I can see this making a case for equipment "warmup" affecting sound. Some of the heat transfer equations use both temperature delta as well as absolute temperature, and the percentage difference of that delta is smaller at higher temperatures. This in addition to components simply having different characteristics at higher temperatures.

    Is there any singing from induced emf in the components? or is it dominantly thermal? I'm just curious if there's an emf component then is there any study on whether an entire pcb might vibrate in sync if the generated emf from the components are all oriented in the same way (then conversely, can it be minimized by changing the orientation of enough components).
     
  8. schiit

    schiit SchiitHead

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    As far as I can tell, it's just a thermal phenomenon. Even in products with very little in the way of EM-spraying components (inductors, etc), they sing--and they only sing when heavily loaded and running a lot of current. In the case of metal can transistors and big plastic-packs like TO247s, you can use a stethoscope to identify them as the source of the singing.

    That said, do I know everything about this subject? No. It's just my experience that in the absence of components that generate and pick up EM, there's not much in the way of field. Now, a LC equalizer....argh, yeah, field galore.
     
  9. purr1n

    purr1n Finding his inner redneck

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    Here's 0.5W into 8-ohms:

    upload_2020-1-17_13-50-43.png

    Looks like distortion still dominates at this level.
     
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  10. purr1n

    purr1n Finding his inner redneck

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    This is both channels driven (note results around post #17 were with one channel driven) and with higher granularity (now that I'm more sure that the resistor blocks won't melt or catch on fire.
    upload_2020-1-17_14-4-6.png

    This was from an earlier post with one channel driven.
    [​IMG]
     
  11. ultrabike

    ultrabike Measurbator - Admin

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    Masking would likely play a big role. I just don't know the general rules.

    I also feel masking is behind great perceived sound, particulary in cases where similar monitoring/recording and reproduction equipment is used.
     
  12. purr1n

    purr1n Finding his inner redneck

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    Here you go. 3kHz sweep from a few mW to 500W. Gets audible toward the end when we are cranking out 200W+.
     
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  13. Superexchanger

    Superexchanger Friend

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    So I went and bought one of these things. After a few days, I'm finding plenty to like.
    More on that below.

    My basement system is really not a typical "audiophile" setup, as the nerve center is a Denon AVR-X3300, and the whole thing has to pull double duty for music and video sources. This is a fine unit and fits all of the source consolidation and routing I need, but from the perspective of the speakers attached (Usher 6381's) I've been disappointed with the performance, mainly with music.

    Usher use these great pulpy Scanspeak clone drivers that behave as a modest load across the spectrum, placed in huge, mass-loaded enclosures, and should theoretically move plenty of air without needing tons of current. With modest efficiency (87 dB/W/m) I suspect 105 Watts of Denon solid state drive might not be enough to wring the best out of them, though. Frequency extension was never a problem, but a lack of impulse and "aliveness" has been.

    Since this entire setup is a bit of a garage-sale build (entirely sourced from craigslist, totaling less than 1K USD), I wanted to avoid paying a large audiophile tax for appropriate power. @purr1n 's impressions suggested this was a good budget option to wake my speakers the fuck up for cheap, and he was right. I purchased a used unit for 240 dollars.

    Installation

    Technically speaking, the setup has some quirks. The unit arrived with a non-defeatable lockout, and the fan was blaring at full speed. I had to download some Harman software to update the firmware, defeat the lockout, and reset the fan speed; be advised that the unit history can have some implications for your setup if buying used, but is easily managed.
    I didn't explore the DSP hooks since I'm not particularly interested in that sort of option.

    Connectivity is somewhat wonky, as well. My AVR source only has SE preouts, so in addition to the XLR>Pheonix adapters I used RCA>XLR cables. The Denon outputs around 4V RMS on the pre-outs, so I'm not too worried about the relative signal drop using SE vs BAL on the Crown's input side. I believe the input sensitivity for the CDi1000 is 1.4 V.

    Finally, I adapted the screw terminals to banana jacks using a cheap set of amazon hardware, with no issues.

    [​IMG]

    Sound impression

    Sensitivity dials set to full clockwise rotation, the Crown swings wider and hits harder than the Denon. I'll essentially echo the previous impressions here.

    In my case, the main change has less to do with different frequency emphasis or tonal balance and more with with an altogether different texture to playback. This is hard to explain. Previously, the presentation was relatively smeared and soft with rolled-off edges, with instrument layering most negatively impacted. I had even wondered if a poor crossover implementation was to blame for this.

    With the increased power I perceive greater agility and heft, a cleaner response with greater force -- two improvements I didn't expect to get simultaneously. Instrument separation/layering, along with the dynamic drive, see the biggest relative gains. Soundstage wasn't noticeably altered, despite larger changes elsewhere. The sum total is that each part of my transducer seems to be more assertively coupled and controlled by this amp, and provides big step towards the palpable texture and immediacy I enjoy with my headphone setup. I don't know if this is 275 Watts into 8 ohms, a step away from class-D amplification, or new toy syndrome, or all three, but I'm really liking the change.

    The caveat is that I'm starting from a pretty modest point with an AVR, may be limited by it as a source, and I'm more likely to be impressed by any dedicated amplifier of reasonable power, but for less than 300 dollars this really is a low-risk investment for anyone wanting to try separates or just experiment.

    Again I'll echo the previous about value and sound. A really nice find.
     
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    Last edited: Jan 24, 2020
  14. Priidik

    Priidik MOT: Estelon

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    XTi1002
    [​IMG]

    CDi1000
    [​IMG]

    There are real differences in the design CDi vs XTi:
    • Most notable is the center piece with black radiators. Could be the G operation, so perhaps the XTi is simple class AB with low quiescent --> making the CDi more attractive at low power listening. Or could be extra regulation.
    • XTi has less output-stage transistors.
    • CDi PSU has 2 bigger output caps.
     
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  15. purr1n

    purr1n Finding his inner redneck

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    Did you use these?

    https://www.amazon.com/Hi-end-Adapt...l&sr=1-1-dd5817a1-1ba7-46c2-8996-f96e7b0f409c

    Nice speakers. Yep, hefty, clean, and focused. Who said 2ch can't be had to cheap. Those Usher woofers are sort of a clone (supposedly better) of these danish Scan-Speak drivers found on the Wilson WATT. They rock for their size, but need big amps otherwise they sound sleepy and mushy.

    Those look like old school three way Usher speakers - probably no worse or maybe better than the modern stuff with the exotic materials drivers.
     
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  16. msommers

    msommers High on Epipens

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    Usher CP-6381
     
  17. purr1n

    purr1n Finding his inner redneck

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  18. Superexchanger

    Superexchanger Friend

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    Bingo! I was sort of worried about having so much exposed metal in close proximity, but I just alternated the orientation of the spade/plug on each post to avoid shorting (UP/DOWN/UP/DOWN) - I can grab a pic later today too. The only issue was the acceptor was a little large, so the plug sits somewhat loosely, but that could just be my cable.

    Lead shot, actually. I was going to use sand, but weirdly shot was easier to get. This was before I had a kid around, but I figured I'd fill the chambers, seal them, and just never open again.

    I was really lucky to find these as cheap as I did. Used market is full of awesome surprises.
     
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    Last edited: Jan 28, 2020
  19. StageOne

    StageOne Friend

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    In my continuing adventure with the Spatial M3s I decided to try out the CDi1000 based on the feedback here. I initially powered them with a singe Aegir and after swapping in a Vidar for a bit I realized I was missing a bit of the low end. I was very content up till that point, so lesson learned. I found this amp with a few scraps/dents at a really good price and it arrived in decent shape albeit with a currently non-working fan. I may have to install the HK software and see if it’s disabled or maybe dead. but..I played it for a few hours and it had no issues heat. No doubt it was designed for a far harsher operating environment than my open air rack.

    I’m fairly impressed with the crown, it does a lot right and not much wrong. And if you can acquire it used at stupid prices, even better. First impressions were solid bass with punch and accurate mid-range/treble. It sort of came across as “polite.” It’s well balanced from bass to treble and sounds even throughout. I found this works best with the Freya in x4 Nexus mode as it give everything more bite and punch.

    For me the best way to describe it is to compare it with the other amps I’ve heard.
    vs Vidar
    - The bass is a half step behind in punch and speed but the mids and treble have more depth, cohesiveness and character. The Vidar can sound a bit flat while the Crown never does.
    - Listening to Jamie Woon Movement, or Sohn Lights they both have a “smacking” bass sound that the Vidar just naiis. The Crown is a close but just misses in tightness and intensity.

    vs single Aegir
    - Much better bass quantity and quality with more neutral mids and treble. It’s accurate and hits all the right notes but misses a bit of the magic.

    vs x2 Aegirs
    - With the M3s, the mono blocks shine but the Crown did really. It’s missing the fine detail and nuance.
    - About !0:30 in with Hans Zimmer Pirates in Prague there is a huge crescendo and the bass/mids/treble start to bleed a little. I lose the instrument separation where the Aegirs stay defined and solid. It doesn’t fall apart and smear the details, but it just can’t keep up.
    - I was surprised how well it did with Melody Gardot, it retained a lot of the sultry character and detail but missed the nuance, that last little bit.

    So far the dual Aegirs are working for me but if they didn’t, I think I’d go with the Crown.

    Aegir x2 > Crown >= Aegir x1 > Vidar

    TL/DR.. The Crown is amazing especially if you can get a great deal on a used one. It does so much right.
     
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  20. Decomo

    Decomo Facebook Friend

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    I am interested in trying pro power amp by purchasing used one. The one issue that I noticed is the unbalanced line out gain from source and preamp is not powerful enough for pro poweramp. If i understood correctly, most of source and preamp unbalanced is 0.775v but most of pro power amp is 1.5v Line In Level. Does this mean that I need some sort of Line level booster to boost the gain?
     

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