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dancheever

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  1. Hi all. I have a early M1 that I just recently had the network card added to. Admittedly other things have changed in the digital chain but there is no question the end result is another level of musicality and fatigue free listening bliss. Im tending to more often stick to a whole full "album" rather than skipping through songs. I'm a analog electronics design engineer for now over 30yrs..and I build everything else in my system myself...but would never be able to do what Bricasti can do. Every design decision or part selection is cost no object...the M1 is not a tweak-able piece..if you do take the machined cover off you will just sit and stare..everything is beyond POOGE..I just replace the cover with full confidence that this piece is as good as it can be. And sit back and listen. I fiddle with other parts in the system. I'm not really a computer geek, per se. I use a $39 BestBuy ethernet server and a solid state NAS. I use a network connected PC running Jriver...from across the room of my listen seat. I cant seem to not get frustrated using the phone app or even my tablet running Jriver. Maybe I'm old school, in that I have to get up and make a conscious decision of what to listen to.
  2. Fwiw, the idea of using a current source or sink at an output node of an op-amp is far from a new one, and if you search the DIY community you'll find out why. Respected designer Douglas Self also uses this method as a means of reducing low level distortion in his commercial designs, as does Nelson Pass. cheers for the well written reply. I consider both Self and Pass as analog Gods and know much of their material. I have not seen this specific topic, I have to admit. My brief cct analysis is correct; The op-amp generates a dc current at the output sufficient to restore OVDC. If this current is greater than the output stage bias current, including signal currents during normal operation, then only half of the output stage is conducting - which simulates single ended operation. Im still having trouble with this. i do see that you will be able to push the op-amp out of the class AB crossover region...but i dont agree that the other polarity device stops conducting. The feedback loop will still wiggle it! Ill study more on this. Im happy that you clarify you aren't pushing this as a common mod. Your trick current sink is neat and much better than what I imagined you did...strap a resistor to a rail;-)
  3. Hi all. I'm new to this group. But not to this single ended "business". I'm a staunch defender of linearity in my digital sources....but prefer Directly Heated Triode Flea amps. meaning, I prefer the challenge and pain of these amps and have trained myself to believe they sound better. I've a M1 and do know Brian of Bricasti. There are some recommended mods that I've installed to my early M1. I'm writing today as I've been wanting to "warn" people about the thread in question...the adding of a current sinc or source to sweeten the treble. I'm also a professional engineer involved in analog my entire career. I won't dispute that the original author heard something, but I dispute that the effect of pulling or pushing on a DC coupled op-amp's output with a current source will force the op-amp to behave "single ended like" , even with an ideal current sinc/source. The feedback around the opamp is DC coupled and the op-amp will fight the shift. I do recognize that the Push transistors will have a different load than the Pull transistors..but neither polarity will never be OFF or out-of-circuit. I will now write that I've a friend with DHT amp (joule-electra 2A3, I believe) and 105dB/W single driver speakers...and he has installed a box between his M1 and the amp that lets him dial in a level of 2nd HD. He swears by this box! He has grown accustomed to this sound. He likes it..and thats what our hobby is about. For those following so far I offer an idea...a real SE output stage after the op-amp. I'm not condoning this or even promising it could fit, but simply describing an alternate way to add the 2nd HD harmonic structure. Visit OP-amp + Class A MOSFET follower - diyAudio. We see a single ended FET AC coupled to the output. One can daydream about miniaturizing this into a socket-able module. At the risk of being called a troll...I need to have a final comment. Adding 2nd harmonics to a feedback amp (line stage or power) does NOT IN ANY WAY reduce the higher harmonics level. It certainly does MASK them if say the 3rd harmonic was at 1%. But in the case of the M1 output stage we have 0.0006% THD at full blast. There are no high harmonics to mask!
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