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Posts by qusp

depend how you implement the feedback and modulator. its just a rough idea, not even a back of the hand scribble, but it should work with the right devices. and thats all i'm saying if for instanvce you look at probably the highest quality class D modules for pro and high power high end these days, fthe NCORE, doesnt have an output inductor and that has led to very nice sounding amps. as with the new high power NCD1200
TBH I cant say I was very impressed with the design for the octave, the digital input and power supply is pretty ordinary IMO. hes hardly the first, comms instrumentation amps, comms logic chips, coms low noise jfets etc have all been used for many years, certainly in DIY. 'made for audio' is not always an endorsement of quality.I did think it was a bit novel, I just didnt think it was all it was cracked up to be. I guess we'll see what he does with the high end model
nope, sorry I think you have misunderstood what we are talking about. there is nothing vaguely like a high power RF fet in the Octave, it uses Industrial Coms DACs.i'm talking about crazy stuff like these LDMOS N-Channel MOS-FET and J-FET normally used for plasma cutters, Broadcast RF and Avionics transponders output Cap of ~100-150pf, silly amounts of power and come in Dual huge Ceramic and gold SMD packages. running $100-1000 each. they are designed for MUCH higher...
what do you call low and at what VDS? quite a few of the parts I mentioned were SiC Jfets and bipolars, but I agree its an area with the mosfets certainly that is a big problem. another thing was the fact that a Semisouth Engineer is working to understand what parameters are important to audio use of these power devices and we may well end up with a new power device for audio. Ciss/Coss/Crss are definitely on the radar and Mike Mazzola is putting some serious time into...
Before I run off with some semi OT rambling, I also must thank you guys for a great article, as has been said it looks as if STAX are a well rounded company, with typically humble Japanese front men and it gives some welcome encouragement to makers of short run high quality 'hand made' boutique audio products. Longevity is possible too, if you have the right attitude and can garner the support and respect of your customers.A few of years ago that may have been true and...
I speak mainly of the ceramics, there is more to specs than voltage and capacity. replacing them how you described will make the circuit performance worse. even replacing with the same type and increasing the capacitance may be worse by setting up resonances. as HF decoupling/bypass caps, the silmics (especially with long inductive leads like that) are completely useless, this isnt a subjective matter.SMD ceramics have low impedance at high frequency and the fact they have...
Handy Ray, I was commenting on the photos posted recently, since they were posted several times and people were talking about following recommendations and buying bunches of Elnas, I made the fairly reasonable deduction people would be replacing the 'crappy ceramics and SMD polymers' as is the current mode. oscon has become the generic name for polymers it seems, I dont use it and I agree with you, terrible signal coupling caps and DC leakage is an issue, but myself I try...
I guess i'm to late, but I can help proof read the manual, it may help that I understand the technical lingo quite well to begin with. I have helped with the translation of several DIY product manuals. ahh its not very technical, you should be fine, though I do think the edits still need some work.
there is no way you have improved performance if those silmic are decoupling caps (well actually at this size they become reservoir caps), you do know that putting the 2 caps in series like that reduces the capacitance, rather than increasing it right? it only increases the voltage rating, which i'm guessing is not what you were trying to do? you will have created a 'cap' that is more inductive, higher impedance and most likely resonant. SMD is the superior format for...
incorrect, it must be rated for the entire voltage ie. the DC offset + signal voltage swingraising the cap to 47uf from 4.7 will lower the 3db point and the point intermodulation starts by a decade (for example 4.5Hz vs 45Hz) if driving the same input impedance, I cannot tell you what the numbers will be without the impedance. how audible it will be will depend on how low that 3db point is, whether it ends up in the audible band and whether your headphones are capable of...
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