ok, I will use 10pf for Cf1 and Cf2. This will put zero at 1200khz where existing second pole of the OP amplifier is there. This will nullify the pole and give about 60 deg phase margin at 3MHz at very low gain and therefore improve the stability of the amplifier. However the interaction between the C1 and Cf1 needs to be examined and value of C1 accordingly estimated. I am yet to try out SPICE for the first time.
I will keep provision for resistance in series with Cf1 & Cf2 capacitors, as suggested by you.
At gain of 14 (23 db) the RMS voltage swing for each IC into 8 ohm load resistance for each amplifier is 14.125V (= 19.976V peak) but if we take into account both ICs, the total voltage swing will be 2 x 14.125V (2 x 19.976V peak) across 8 ohm speaker, hence total power output is (square of 28.250) / 8 = 4 x (square of 14.125) / 8 = 4 x 25 W (The P referred by you is nothing but 25W, which is the power output by one IC working in single mode across 8 ohm load.)
I will keep provision for resistance in series with Cf1 & Cf2 capacitors, as suggested by you.
At gain of 14 (23 db) the RMS voltage swing for each IC into 8 ohm load resistance for each amplifier is 14.125V (= 19.976V peak) but if we take into account both ICs, the total voltage swing will be 2 x 14.125V (2 x 19.976V peak) across 8 ohm speaker, hence total power output is (square of 28.250) / 8 = 4 x (square of 14.125) / 8 = 4 x 25 W (The P referred by you is nothing but 25W, which is the power output by one IC working in single mode across 8 ohm load.)
I don't understand why so many who build the Orion speakers, try to use least expensive inexpensive amplifiers. Doesn't this defeat the purpose of having a revealing speaker system. I would think everyone would like low feedback class A amplfiers for this purpose. No? Im also wondering why the Linkwitz ASP is not done with DSP instead thus it can be updated with a mere software change.
If you believe that the only revealing amps are low feedback, class A types. SL clearly doesn't believe this and neither do I. A design using all class A amps would struggle to be all in one box, given the number of channels involved. It would also demand huge power to play at appreciable volumes. Having separate amps would then necessitate interconnecting cables which would rather tend to compromise the transparency would it not?
I'd hazard that this is because SL doesn't consider himself good enough at DSP software and DAC hardware design to deliver it. A third party might eventually come up with a design though, and SL seems to be encouraging such on his website.
SL started this series of loudspeaker designs in the late 1970's. It's been a huge number of small refinements. So I suppose that a young engineer with all the skill of SL could design an equal DSP/DAC system in 30 years or maybe less.
But it really sounds like a solution is search of a problem.
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By this do you mean a digital implementation of the ASP? If so then I can see at least one major advantage of going digital - it makes the design fairly generic rather than something dedicated to SL's designs. With all the flexibility of DSP, the thing could be configured to a whole host of different active setups, all using the same hardware. Economies of scale can work wonders in electronics
Not having to worry about capacitor tolerances is a fairly minor upside, given that NP0 ceramics are typically 5% (can be hand selected to be closer if required as tempcos aren't the limitation). Drive units don't generally achieve simiilar levels of repeatability AFAIA.
I think the "generic" aspect is a side issue (or feature.)
I think what speedskater is saying is, that even if implemented digitally (dedicated or otherwise), the final solution won't improve the performance of the greater system relative to the ASP. And possibly might reduce the level of performance....depending upon implementation. (I've seen a few of these first-hand.)
SL doesn't discourage efforts in this area, but he's skeptical.
Sorry for the off-topic post.....since this thread is concerning power-amps.
Cheers,
Dave.
I think what speedskater is saying is, that even if implemented digitally (dedicated or otherwise), the final solution won't improve the performance of the greater system relative to the ASP. And possibly might reduce the level of performance....depending upon implementation. (I've seen a few of these first-hand.)
SL doesn't discourage efforts in this area, but he's skeptical.
Sorry for the off-topic post.....since this thread is concerning power-amps.
Cheers,
Dave.
I think what speedskater is saying is, that even if implemented digitally (dedicated or otherwise), the final solution won't improve the performance of the greater system relative to the ASP. And possibly might reduce the level of performance....depending upon implementation. (I've seen a few of these first-hand.)
Well if it doesn't at least equal the ASP's sound quality then I'd agree it wouldn't be worth bothering with. But I've no reason to assume that it couldn't, competently implemented. Plenty of less-than-competent digital XOs out there, I'll grant you
I noticed that Linkwitz displayed the Orion at RMAF with Pass amplifiers. Why would they do that? If someone gave you the Pass amps for free would you still be using chip amps? Everything in the signal path effects the sound. At least in my experience. Using $2,000 worth of drivers with cheapo amps make no sense to me.
I've heard a phono preamp done with DSP (Metric Halo) that is better than any analog phono stage I've ever heard. Including the most expensive.
I imagine the ASP done properly with DSP will be much better than putting the signal through all those op-amps and many passive components. Also avoids replacing boards with every revision. So may be reduce cost in the long run too.
I've heard a phono preamp done with DSP (Metric Halo) that is better than any analog phono stage I've ever heard. Including the most expensive.
I imagine the ASP done properly with DSP will be much better than putting the signal through all those op-amps and many passive components. Also avoids replacing boards with every revision. So may be reduce cost in the long run too.
With Orion 4.0 SL & Don Naples seem to be aiming for a larger share of turnkey systems (as opposed to DIY) and I think they understand that a substantial fraction of retail audiophiles wouldn't give the speakers a second listen if not driven by exotic and overpriced electronics. The reality is that amplifier channels in the Orion system drive a single or pair of identical drivers directly over a restricted frequency range without the challenges of pushing through a complex passive crossover network. To the extent that exotic amplifiers earn their keep it is stability and clarity driving difficult loads...not an issue with Orion. They sound sweet indeed behind good workmanlike amps like ATI, Sonance, etc.
I agree with Pacificblue, your gain calculation is incorrect. If you bridge two identical power amps the voltage gain increase is 6db. You don't consider power (or the load) in this calculation.
Here's an experiment to prove it. Input 0.5 volts RMS into your amplifier and then measure the AC RMS voltage across the two bridged outputs (where you speaker(s) would be attached.) You'll measure 14.1 volts RMS. That's an Av of 29db.
Regarding the schematic: I don't think I would bother with the offsetting circuitry. There's not going to be enough to even worry about if the amplifier is working correctly.
Cheers,
Dave.
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Or, assume the high dollar amplifiers are partly responsible for the excellent sound of the speakers and make the assumption cheaper amps are not suitable.
I think it would be better to hide/obscure the amplifiers for audio shows. But then you'd spark curiosity from the auditioners about the "mystery" amplifiers and they'd get distracted with that.
It's a real double-edged sword and a no-win situation dealing with audiophiles.
Cheers,
Dave.
No Kuldeep, the amplifiers come first and then the speakers will be done.
But I have heard open baffle speakers and they outright beat the boxed speakers,IMO.
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