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Raal Ribbon Headphones - SRH1A

Discussion in 'High-end Audio Forum' started by once, Oct 7, 2018.
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  1. llamaluv
    I couldn't wait (so predictable, I know) and have a used Bryston 2.5 SST2 on the way. I plan on using it as a point of comparison with anything I'm able to test in the near future and/or until a certain amp I really want comes up used somewhere. That, and it's also possible I may end up liking it on its own terms. :)
    HoloSpice and Zhanming057 like this.
  2. Thenewguy007
    If you do ever buy it, share your impressions of it.

    I'm always weary of Class D amps, I get the sense that they are the economy model of amplifiers.
    HoloSpice and dm24 like this.
  3. Aleksandar R.
    Hello everyone,

    I'm glad to let you know that RAAL-requisite will be at CANJAM Singapore, showing SR1a headphones via SLT Technologies as our distributor.
    HoloSpice and Zhanming057 like this.
  4. Zhanming057
    If you get a chance to spend some time with one of the Esoteric Integrateds, they will quickly disabuse you of that notion :)

    Esoteric makes incredibly well-designed, seriously over-engineered, $10,000 class-D power amps that have absolutely no problem going toe-to-toe with the strongest class A systems and being 90% efficient while doing it. A 200w amp running cool is a sight to behold.
    HoloSpice likes this.
  5. Venture Guy
    I worked on Class D amps 20 years ago. Even back then they sounded pretty good. Fast forward to now... People I know with Golden Ears are pretty much in agreement that the Hypex and ICEpower Class D amps blow away Class A/B:)
    BreadMaster and HoloSpice like this.
  6. Aleksandar R.
    Dunno about the new ones, as I gave up on Class-D 10 years ago, but back then, while all nice and fine at a first glance, they obviously lacked resolution. They simply ignored low level signals. The dynamics is there, open and fast, but the background was always too black and highs were "simplified" in lack of a better term. Some think "jet black background" is a quality, but it isn't. It actually comes from ignoring low level signal.
    I must emphasize, I don't know what's been done in the last decade, but I never got a wish to try them again, as I believe that this is inherent flaw of PWM that has limited signal dynamic range (whatever their S/N ratio may be). PDM (pulse density modulation) should be better, but manufacturers don't really tell whether it is PWM or PDM or something else, so I don't want to make "blind" purchases just to realize it's flawed and chuck it in the darkest corner of my listening room to never turn it on again.

    While we're all throwing around Class A, Class A-B terms lightly, like we know how they will sound, at least it's some reference for making a choice.
    With Class D designs, there's equal number of different modes of operation, but it's not advertised as such, it's all dumbed down.
    I would surely like to know what methods are used to chop the signal and control the pulse width, frequency and duration, so I could try to make a choice that is not based on believing the sales pitch laced with latest buzzwords, but on actual information.
    Thenewguy007 likes this.
  7. Venture Guy
    I think you need to listen to a Hypex amp... Not to put too fine a point on it, but the ES9028 DAC used in the Benchmark DAC3 goes to a SINGLE BIT sigma delta output stage. And, we all know how good that sounds:)
    Last edited: Feb 21, 2019
    Bill13 likes this.
  8. Zhanming057
    Alex, if you do ever get a chance to try out power amps or integrated amps from Esoteric, do give them a shot. Esoteric uses the inherent efficiency and relatively low parts cost of Class D solutions to heavily invest in power delivery and tuning, they claim that 10,000 hours of actual data provided by testers goes into the tuning of the I03 and I05 amps. And I will go on record to say that the I03 is every bit as impressive of an integrated system as the best products from Simaudio, Spectral and Pass labs. They don't sound "digital" at all - my best description is fast, clean with solid midrange density.

    I know a couple people who run your tweeters in Hong Kong from Esoteric systems, and the setups were very impressive. It's a bit of a faux pas to even bring up Class D in Western audiophile circles, but when you spend the same R&D as top Class A amp builders, and use the same level of material quality and put in the tuning effort, the end result can be exactly as good.
  9. Aleksandar R.
    I'm thinking of offering our amp for our power-hungry headphones so I would like to try Hypex Ncore, but some module for which I could do my own linear power supply, comparing it to some Ncore that uses onboard SMPS.
    However, I will certainly create a chance to listen to the Esoteric offerings, just to get a better picture of what has changed in Class D in the last decade.
    Also, the candidates for R-r amp are Neurochrome error correction linear amp modules, ICEpower modules (less likely) and a custom made old-school quasi-complimetary amplifier that I'll get for trials soon enough.

    This idea of R-r amp is still in initial phase, so everything is on the table, but I definitely have an itch to try modern Class D designs!
    HoloSpice and Zhanming057 like this.
  10. Venture Guy
    I was talking with Morris Kessler of SAE fame and now CEO of ATI. He is a complete stickler for accuracy. His new amps use Hypex modules with... SMPS. He said the sound was better than with an LPS. You could put the whole amp inside your interface box and it probably wouldn't even get warm.
    Bill13 likes this.
  11. Venture Guy
    @RAAL requisite Alex our conversation got me motivated to look at the Hypex Ncore datasheet. Their smallest amp is stereo delivering 125 WPC into 4 ohms. It has a .002 ohm output impedance and can deliver 10 amps for 50 milliseconds before the current protection circuit shuts the amp down. Assuming the amp is stable, you might not need ANY compensating resistors... Worst case, a much smaller one.
    Last edited: Feb 21, 2019
    HoloSpice likes this.
  12. Bill13
    As a RAAL ribbon tweeter user, I wholeheartedly concur that Hypex Ncore amps with SMPS is way to go - especially considering bang-for-the-buck.

    Furthermore, SMPS implemented properly is indeed preferable to LPS. As I recall, Rob Watts (Chord) explained the reasons in one or more Head-Fi posts (provided solid engineering facts).

    IMO, Hypex Ncore with SMPS sounds better to me than the many high-end solid state class A, class A-B, and tube amps that I've heard. If buy Hypex, make sure you get the Ncore tech version.

    My Hypex Ncore amps should sound great with the Raal SR1a headphones scheduled for delivery tomorrow.

    With all due respect: I don't think there's justification to spend $10k for 2-channel amp(s).
    Last edited: Feb 21, 2019
  13. Venture Guy
    Eagerly awaiting first impressions...
  14. Zhanming057
    It's all a matter of perspective. Is there justification in a $1,200 smartphone or a $100,000 sports car? Nagra is so fantastically overengineered that I can drive my IEMs out of the 100w taps, and I cannot notice any noise floor at all. Spectral's high end stuff presents treble control like no other brand, and it's something I can only get a taste of, since I am running one of their older power amps. And then there's materials and build quality, a power supply custom built in Japan or heavy guage CNC'd aluminum can be quite expensive. But I do agree that past the $2,000 or so price point, you are largely paying for overengineering, sound improvements are relatively small and you have to appreciate the design and work for what it is.

    The nice thing about the SR1A's is that they open the world of 2 channel amps up to headphone enthusiasts, and there are great choices at every price point.
    HoloSpice likes this.
  15. Aleksandar R.
    While SMPS is better because it can be regulated and it doesn't have hum noise, there are two problems with it that make it sound "thin" compared to LPS:

    1) While regulation may hold the output voltage constant (it won't, read later), the caps are still too small to have low impedance in low frequencies. As in most amplifier topologies, for the AC current that goes through the speakers, the electrical circuit is closed through the PSU caps. They are in series to the speakers. They are sized adequately from the vantage point of PSU for smoothing out the HF switching noise but they are not large enough to be in series to the speakers, unless you're leaving it to the amp feedback to recover a bit too early bass roll-off.

    2) They are always overrated for the actual power they can supply. For example 300W rated SMPS is more like only 100W continuous power. That is because the manufacturer assumes the crest factor of 6 dB (average music power is 6dB lower than peaks). The problem is that it will hold current and voltage for about 100ms and then the current/voltage limiter will kick in and start reducing pulse width and voltage and current will start drooping as fast as those small output caps are depleted. Not good for long notes in bass.

    I have yet to hear a SMPS powered amp (including my beloved Benchmark AHB2) that sounds as full and rich in bass and have a slam as an amp with a beefy LPS. The guys from Esoteric do know why they chose LPS instead of SMPS.
    Also, some PSU caps sound much better than other PSU caps and I have yet to see a good sounding caps used in SMPS.

    So, my preference goes to a double-power EI transformer (no toroids and no crest factor applied) LPS with 40000-50000uF per rail per channel, preferably with multitude of small Cornell-Dubillier 381LX caps VS. resonant mode zero-crossing switching SMPS, any day of the week.

    Besides, for Class D, which is the most dynamic load for PSU of any amplifier class, the best power supply is a battery...No current limit, no noise, no small caps in series to the speaker...

    So, if there will be a R-r Class-D headphone amp, it will probably get supplied with gel-acid lead or Li-ion batteries.
    Last edited: Feb 22, 2019
    Thenewguy007 and Zhanming057 like this.
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