Different modulator topology.
What are you calling 'algorithm'?
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2nd generation EIGENTAKT PURIFI 1ET6525SA (successor to the 1ET400A)
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What are you calling 'algorithm'?
Ah, I don't know if BP has optimized his design tools.
What is important behind this quote is that the amplifier is entirely mathematically modeled. This allows to predict it's behavior in any situation, and as a consequence optimize the various parameters to fit a set of criteria. This was already the case for the first generation Eigentakt.
What is important behind this quote is that the amplifier is entirely mathematically modeled. This allows to predict it's behavior in any situation, and as a consequence optimize the various parameters to fit a set of criteria. This was already the case for the first generation Eigentakt.
PEQuestrian
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Preordered a Boxem stereo model. Looking forward to "not" hearing it in my HT setup ;-)
I don't know what takes them (Purifi) so long to update the website and upload the datasheet of a new module. Should be a few hours work really.
That is quite the significant improvement over the 1ET400A along with the greater power bandwidth increase to 80kHz like the 1ET9040BA, I would be using a Denon X8500H & Klipsch RF-7 III floorstanders, I should've waited on the 1ET6525SA later this month, a bit silly of me to purchase a 1ET400A based amplifier back in June that is already some 5 years old, missed the announcement by 1 month
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You still have an amplifier with one of the best modules available on the market. And, as I written previously, this is an improvement measurable only when both the input/gain stage and the source are ultra low noise.That is quite the significant improvement over the 1ET400A, I would be using a Denon X8500H & Klipsch RF-7 III floorstanders, I should've waited on the 1ET6525SA later this month, a bit silly of me to purchase a 1ET400A based amplifier back in June that is already some 5 years old, missed the announcement by 1 month
The lower noise floor would not be noticeable because your source is noisier. And the extra frequency response is way beyond what we hear. So this upgrade would be inaudible, you are not missing anything really. Enjoy your system.That is quite the significant improvement over the 1ET400A along with the greater power bandwidth increase to 80kHz like the 1ET9040BA, I would be using a Denon X8500H & Klipsch RF-7 III floorstanders, I should've waited on the 1ET6525SA later this month, a bit silly of me to purchase a 1ET400A based amplifier back in June that is already some 5 years old, missed the announcement by 1 month
Like smartphones, there is always going to be something new coming out, and now also like smartphones, the improvements are so small and incremental that keeping last models is still quite up to date.
@Matias Thanks for that, I was just curious why Class D is particularly limited in its frequency response compared to Class AB, the Benchmark AHB2 is considerably broader at 0.1Hz-200kHz & Classé Audio's Delta Stereo/Mono amps claim a frequency response of 1Hz-650kHz, is it simply a case of highly inflated marketing specs?
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glideslope
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Output LPF.
This is the frequency response of the Classé when measured by stereophile
LPF is part of the control loop for Hypex/Purifi amplifiers, it has no direct influence on the bandwidth.
As @boXem said bandwidth is not necessarily related to the output filter though it may be part of what limits bandwidth.
Modern class D designs provide very wide internal bandwidth and much higher loop gain than typical (most, probably all) class A or AB designs. That is the reason for their lower distortion, lower output impedance (higher damping factor), and so forth. The output filter to reduce switching noise is above the audio band and included in the feedback loop so not a direct contributor to bandwidth, which is determined by loop gain and thus primarily (IMO) noise, distortion, and stability criteria. Like any other amplifier, bandwidth is a design choice, and likely driven by marketing since bigger numbers are often perceived as better. With class D switching speeds running in the 500 kHz range, bandwidth well beyond the audio band is easily achieved, and 50~100 kHz is way beyond what we can hear and/or want to send to any speaker. Without class D's high loop gain and internal bandwidth, class A and AB designs typically require greater bandwidth to achieve the same distortion and flatness specs to 20 kHz, making their greater bandwidth a limitation and not a feature.
From a design and use point of view, excessive bandwidth is not usually a good thing. Higher bandwidth means greater noise, more issues with stability, more power needed (wasted) to support the wider bandwidth, greater potential for sending ultrasonic signals to the speakers (goodbye tweeters), and so forth. Wide bandwidth can reduce high-frequency roll-off in the audio band, but whether the amp is -0.01 dB or -0.1 dB at 20 kHz, it is going to be inaudible. It can also reduce phase shift at very high frequencies, but again that is almost certainly inaudible, and both roll-off and phase shift in an actual system is so far dominated by the speakers that the amplifier is inconsequential.
I remember, not fondly, the bandwidth wars of the late 1970's and early 1980's when "wideband" amplifiers were all the rage. Blown amplifiers and tweeters were not uncommon, as well as sensitivity to RFI/EMI. Having an audio amplifier that could serve as an AM radio transmitter is not necessarily a feature.
I rarely look at bandwidth beyond the 20 kHz full-power roll-off just to ensure it is not excessive (more than maybe 1~3 dB down at 20 kHz). Power output, output impedance (damping factor), noise, and distortion are way more important and relevant to the sound. If two amplifiers have similar specs in the audio band but one has 500 kHz bandwidth and the other 50 kHz, I will choose the 50 kHz amp as it will probably have lower wideband noise and be more stable (less sensitive to the speakers' reactance).
FWIWFM - Don
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glideslope
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Could you provide an example of this please?
When I look to block diagrams in Hypex white papers & Self amps book, NC400 schematic, BP interview transcripts, and so on - I find the load and the feedback loop connected to a large inductor and large paralleled caps after the power FET's. Both the output and the feedback would be influenced by the filter. I've been unable to find a diagram or schematic with a filter like this only in the feedback loop.
https://www.hypex.nl/media/5c/19/2e/1682341812/Simple%20self-oscillating%20class%20D%20amplifier.pdf
The output filter in modern self-oscillating designs is part of the oscillator.
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