Purifi Class D: Junk?
Datasheet: The output drives a 100Ω load
Sorry, just looked at my notes, the MSB’s output buffer could be the LT1819 https://www.analog.com/media/en/technical-documentation/data-sheets/18189fb.pdf Cheers George |
atmasphere, The issue is performance, and without a proper low impedance buffer, at the input, not 6 feet of cable, with capacitance and inductance, the performance suffers in my testing (with actual test equipment). I don't doubt he did it, just pointing out that it is not an optimum implementation. |
No they are the output buffers in the rear of the MSB discrete R2R dac, which can swing 7.5v and do it with ease into 2kohm, with no temp rise or voltage drop or heat sink needed into the raw NC500 moduleDid you test to see if they actually do that in this application? There are a lot of variables here, not the least of which is how surprising 1 watt of power actually is and how distortion can affect your perception of sound pressure, to say the least. The issue is performance, and without a proper low impedance buffer, at the input, not 6 feet of cable, with capacitance and inductance, the performance suffers in my testing (with actual test equipment).As you might know our MP-1 is a tube preamp but can drive this through 30 feet of balanced cable with no worries- but that is our module, not a Hypex or the like to which I have no exposure. I would think that due to the low impedances involved the interconnect issues wouldn't be an issue. But there is a lot to unpack here; IMO the whole thing can be taken with a grain of salt without more information. |
Did you test to see if they actually do that in this application?Yes, that why I said it. I would think that due to the low impedances involved the interconnect issues wouldn’t be an issue.And to have the MSB buffer at the Hypex input or 1mt away with quality interconnect, is no difference at all and you know that. But what is worse, is having one buffer in series with another buffer. When if one "can" if loud enough do the job perfectly and yield even better sonic results. You have probably already seen this, but again for the masses, from the Hypex NC500 data sheet. Audio input"good way of tuning in a “house sound”" Take that as I would as colouration distortions, countering what they say earlier in the same sentence as "The NC500 is practically devoid of any sonic signature ” And this is what you hear by not! having an extra buffer in series that’s not needed. |
From Nord Acoustics; All Purifi 1ET400A are modular, PSU, AMP, and buffer. Making them easily upgradable in future developments of our Input Buffer. They are also easy and open to maintain. The REV D Buffer board uses modern versions of an old Op-Amp used primarily in Studio mastering and mixing equipment. Their development was focused solely on Audio performance and has been bought up to SOTA design and performance. Rev D will also accept the previous 8 pin Sparkos and Sonic Imagery Op Amps. Details of Op Amps Click Regards |
