My perspective is different. I 'see' all equipment as good enough, just that the designers and manufacturers haven't gone far enough to ensure robustness, in the field.
An analogy would be an 'imaginary', 🙂, Italian sports car that had excellent performance, but every time it hit a bump on the road various bits inside the car would fall off, knobs would come off in your hand, and the gearbox would jump into neutral ... 😀
sorry I should have been more specific. they have listed sot23 as a possible package for their LSK170 for some time, but I have never seen one, perhaps you need to pay for a large order. I wasnt asking what they provided to you, I was asking if you knew if they were making the LSJ74 available in a matching sot23, having an NP pair available in sot23 would be pretty sweet IMO. I mean the bf862 is an excellent part and we can do a LOT with just the N-channel, but...
I see, no I don't know that. The 170 and 74 are available afaik in SOT23 and TO92 but single.
jan
I used the LSK170 in SOT23 and the build was not large, 2 pieces per board and I doubt we ran more than 25 boards.
I try to reduce the effect of mains as much as I can on each of piece of equipment in the chain but despite this I still notice a small improvement when I add some mains filtration.
I'm wondering . . . do you take conscious measures to reduce how much your designs pollute the mains as well as considering how much the mains may affect them ?
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Of course, Mikelm, I try to remove EMI as much as possible, especially as it seems to be getting worse on the power lines and in the air, as well.
For example, I always use R-core transformers or special E-I's for lower transfer capacitance in all my preamps. I would do it for my power amps, but it is just too expensive. I would appreciate any input some designers out there for improving the EMI rejection in power amps with Toroid transformers, as this is an area that I do not think is done well enough yet. I know that Charles Hansen does more than me in this area, and I admire him for it.
For example, I always use R-core transformers or special E-I's for lower transfer capacitance in all my preamps. I would do it for my power amps, but it is just too expensive. I would appreciate any input some designers out there for improving the EMI rejection in power amps with Toroid transformers, as this is an area that I do not think is done well enough yet. I know that Charles Hansen does more than me in this area, and I admire him for it.
cool, no worries, sorry I was unclear again, my NP pair I just mean a pair of sot23 still singles, but both N and P available, unlike the bf862 and other modern SMD jfets which are always just N. thanks for the info, hopefully they start responding to requests more readily.
hey thats good news, I emailed them a couple times a while ago asking about 100 of the 170 in sot23 and got no reply i've only seen the N-channel 389 pair in soic8 and the 170 in to92, though i've seen the sot23 elsewhere once, cant remember where … ive not pushed it as I prefer the 862 anyway.
as a pair they become interesting again. I wonder if this means they will release an LSJ109 soon.
Interesting when I compared EI vs toroidal on my amps before I added choke regulation, the EI transformers were clearly subjectively superior so I adopted them as standard.
After some experimentation with different post bridge filtration methods I eventually settled on full differential EI choke regulation in all power lines ( rails & earths ). Big heavy Chokes of about 2mH. Not sophisticated but very effective.
Later I tried switching the power transformer back to toroidals and discovered that with the differential EI chokes in place now the toroidals power transformers sounded better than the EIs I'm guessing because of lower external fields.
So that's where I am now . . . not very interesting if your looking for a cheap or light solution but very effective and satisfying if you have any luddite tendencies like me 🙂
I'm sure using smaller toroid differential chokes followed by some kind of active regulation might be just as good, or better. I actually have some boards made up ready to check this out but just didn't get around to it out yet.
I can't imagine that any of the above is news to you John but perhaps sometimes simplest might be best ? ? ?
I gather that you are not so fond of CFP o/p stages but what I wonder what you would think of a CFP on the o/p of a cap multiplier regulator that never switches off. To me it seemed like a good compromised between ZFB regulation & closed loop regulation.
mike
Copper shield between windings and (important!) common-mode filtration on the transformer secondary as well as the primary. Agreed that it's easier to start with R-core or dual bobbin, but I've gotten toroids to work with some pretty sensitive amplification.
If you are going to reduce the power line noise (conducted emi) you need to figure out how to measure and quantify it. Since there is both normal mode (line to neutral/line to line) and common mode (power wires to everything else) its quite the challenge to really see if the fix works. Fertile breeding ground for magic and witchcraft.
I have heard reports that reducing the noise led to a "less involving" audio system.
I have heard reports that reducing the noise led to a "less involving" audio system.
The noise is often different for anothers invironment and so the specific design application to one doesnt always work as well when used for another place. A wideband filter is needed to cover everyone's situation. Or, you measure and design a filter for those freqs at your location. But I covered this earlier in the year and even showed photo's of freq spectrum of the type of noise and freqs on the ac line due to specific connected equipment on the line.
THX-RNMarsh
THX-RNMarsh
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Allowing some noise through can add a sense of ( false ) excitement but I think that ultimately it detracts from true fidelity.
When I added mains filters to my amps a while back the system did sound a little flatter than it did before . . . so I added some more filters to my dac and it came back to life again 🙂
I've done a fair bit of simulation of the the entire path from input poor quality mains through to the rectified and smoothed voltage rails, using real life parts, i.e. parasitics included. Which shows how bad the problem is ...
But it's helped me to work out a strategy for filtering which doesn't rely on brute force components external to the component. This is what I use on my recycled HT beast, and subjectively it's highly effective in making the supply, as is, work better, plus largely eliminate interference effects. Not 100% perfect in doing this, but the remaining subtle influence may be more RFI related ...
But it's helped me to work out a strategy for filtering which doesn't rely on brute force components external to the component. This is what I use on my recycled HT beast, and subjectively it's highly effective in making the supply, as is, work better, plus largely eliminate interference effects. Not 100% perfect in doing this, but the remaining subtle influence may be more RFI related ...
This is very much part of the tweaking experience - quite often the improvements make the system sound subjectively worse, 😱, so the tendency is to think you're going in the wrong direction - for me it's often that the sound becomes rowdier, more aggressive ...
But, what's really happening is that another weakness is now transparently revealed, its impact is shown to be quite severe ... and so that is where one's energies now have to be directed, to nail what's causing that problem ..
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Agreed 100%
There are people on this site who seem to prefer to just trust their ears and don't seem concerned if the measures they take to please their ears aren't particularly logical ( like deliberately adding noise ) but for the reasons you have stated above this is not my approach. I think following what we could call a 100% subjective approach could very easily lead to a sub-optimal result.
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Which is yet another reason why cleaning the mains supply in ones' home is effective.
I am struggling to see how a cap multipliers and good on-board filtering don't fix noise coming across transformer inter-winding capacitance. The way you people talk, it sounds like there's a 1 kW AM transmitter just the other side of the mains plug.
Live- neutral cap
Common mode choke
Screen
Secondary filter
Cap multiplier
Good earthing practice
Problem solved
Please show waveforms before we go on another Blowtorch wild goose chase.
Live- neutral cap
Common mode choke
Screen
Secondary filter
Cap multiplier
Good earthing practice
Problem solved
Please show waveforms before we go on another Blowtorch wild goose chase.
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