The op-amps are the TI OPA1612 chips. You would have to talk with Buckeye to see if they have considered upgrading those chips to Bruno's recommended TI op-amps, at least on their Purifi amps. Of course, that would probably also mean upgrading the circuit boards being utilized in Dylan's builds. Whether or not that would make the price of the amps cost prohibitive for Buckeye's apparent market, I don't know. It would definitely require a redesign of some kind.
The idle power needs to be updated/added to the site. In the NCx thread earlier today I mentioned we are working on incorporating an idle feature for the Micro Audio SMPS'
Has their been a stated specific reason as to why Bruno recommends the 1656 with his Purifi modules? A particular "house sound" characteristic or signature perhaps?
Absolutely no house sound involved in the equation, as the whole point of Bruno's (and Hypex as well) designs is neutral/uncolored sound. Which both the 1612 and 1656 abide by.
Any update on the idle feature? Thanks
Any differences should be below the limits of human hearing.
I believe the Nilai is only available for DIY projects and not for commercial applications.None. NCx500 provides more power though. The current roughly equivalent modules are Purifi 1ET400a = Hypex Nilai, and Purifi 1ET7040SA = Nypex NCx500.
The latter have more current-handling capacity and higher max output power. IMHO there are rather limited home hi-fi applications where those are needed and the 1ET400a or Nilai will be more than adequate in most cases. I'm sure someone will jump in to disagree with me on that though.
Can you have too many watts?None. NCx500 provides more power though. The current roughly equivalent modules are Purifi 1ET400a = Hypex Nilai, and Purifi 1ET7040SA = Nypex NCx500.
The latter have more current-handling capacity and higher max output power. IMHO there are rather limited home hi-fi applications where those are needed and the 1ET400a or Nilai will be more than adequate in most cases. I'm sure someone will jump in to disagree with me on that though.
I hope I’m not jumping in here but I’d urge a little caution when considering the output power of class D amplifiers. The best deliver what they say, However perhaps we’re used to class AB amps with transformer, rectifier capacitor power supplies and output stages with very little current limiting. These amps would happily deliver power into low impedance speakers until the power rail slowly begins to sag and we hit voltage limit. With class D amps and switched mode power supplies the limit is a hard limit. First off the quoted current limit is a typical peak value not the guaranteed limit of a unclipped sine wave. Secondly there is a thermal limit to the module and its assembly. The ability to dissipate heat may be restricted in some constructions. The class D amp may very wisely decide to shut down if it overheats in a low Z load. Lastly a SMPS will shut down quite sharply if excess power is drawn.None. NCx500 provides more power though. The current roughly equivalent modules are Purifi 1ET400a = Hypex Nilai, and Purifi 1ET7040SA = Nypex NCx500.
The latter have more current-handling capacity and higher max output power. IMHO there are rather limited home hi-fi applications where those are needed and the 1ET400a or Nilai will be more than adequate in most cases. I'm sure someone will jump in to disagree with me on that though.
All true, and as you say, perahps doesn't matter too much. Maybe, what should be better understood is what happens when the amp reaches its limit i.e. does the amplifier's protection circuitry gracefully handle the situation?I hope I’m not jumping in here but I’d urge a little caution when considering the output power of class D amplifiers. The best deliver what they say, However perhaps we’re used to class AB amps with transformer, rectifier capacitor power supplies and output stages with very little current limiting. These amps would happily deliver power into low impedance speakers until the power rail slowly begins to sag and we hit voltage limit. With class D amps and switched mode power supplies the limit is a hard limit. First off the quoted current limit is a typical peak value not the guaranteed limit of a unclipped sine wave. Secondly there is a thermal limit to the module and its assembly. The ability to dissipate heat may be restricted in some constructions. The class D amp may very wisely decide to shut down if it overheats in a low Z load. Lastly a SMPS will shut down quite sharply if excess power is drawn.
Now this would be OK perhaps if 4 Ohm speakers were just that. But look at some of the better speakers on the market - here is a review by @John Atkinson in Stereophile of the KEF Blade 2 meta where he measures the load presented to the amp.
This drops to 2.8 Ohms in the mid bass region where all the audio power is. In fact many 4 Ohm speakers behave this way.
If you talk to BoXem or March Audio they would recommend the use of amplifiers employing the 1ET7040 module if you want voltage clip to be the limiting factor for such a load BoXem suggest a 3 Ohm limit for the 1ET400 modules for instance If you want voltage clip to be the limiting factor.
But let‘s not get too obsessed here - I drive a set of KEF Blade 2 metas with a March Audio P501 (7040 based) and I hit an unpleasantly loud peak SPL of very approx 110dB at the listening position with the DAC set at -10dB or approx 25W/8 Ohm. So perhaps this all doesn’t matter too much anyway!
I suspect voltage clip on some amps may be more benign than current limiting. But pictures of Purifi amp waveform in current limit seem just fine. Are all the other amps as good? And what happens if the SMPS collapses?
About to begin final testing of our production model in the coming weeks.
