This is not to you only.....
How can some of you EE guys miss the point so badly!
The subject is back-emf. Relating the Q to freq resp etc is Not on target.
I asserted that the back-emf is highest at resonance. My idea to sample the current with a small series R fed back into amp does significantly lower the driver's distortion at and around resonance. It was measured and reported in an article I wrote in TAA. Complete with schematic, how-to, test data before and after.
Decades ago. Did anyone here read it? I think Joe is attempting to explain it. But it does work and works well in practice.
As I said before, it would help a lot to try to find an explanation when people actually really do hear changes and improvements (lower distortion etc).
THx-RNMarsh
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Perhaps this is because no coherent point has been made? Just some rambling based on confusion about electromechanical systems, simple electrical circuits etc. Every time Joe tries to explain himself again he drops himself right in it by making elementary errors. Why should we assume he has something deep to tell us when he clearly doesn't understand trivial matters?RNMarsh said:
Nothing else than an equivalent RLC circuit. The only difference is that the speaker is non-linear. If you put iron core coil into the RLC model circuit impedance, you get it as well. Though different. That "back-emf" evil is a non-issue.
Dan,
I listen to music in the hayloft of our barn. It is freezing cold and damp in winter and often bone dry and boiling hot in summer.
Sometimes in the winter it will rain nonstop for a month, and if I am not careful everything becomes damp with the risk of mould. The rig is kept spotlessly clean. Gathering dew at dusk and dawn forms in between contacts, expands and contracts, attracts dust and organic particulates. The horn speaker will often sound leaden due to the damp air. Batteries will underperform to give less dynamic range with a fall off in bass.
I take everything apart, clean all contacts and put it all back together exactly as it was. Batteries are recharged whenever I hear the sound quality declining. When it gets down to about -10C, I take all the electronics and batteries up to the house, and mothball the horn speaker in a tarp with a couple kilos of silica gel. And switch to wearing headphones.
I don’t see all this as much of a problem really, just a matter of basic chemistry and physics. No fancy stuff, just bottom shelf electronics that match well together.
The best sound I get is in summer, with everything clean and dry, freshly charged batteries (PbH2SO4 for amp, NiMeHi for valve buffer+guitar pedal eq, and LiPO4 for iPod) with an ambient air temperature under 30C.
ToS
Maybe it does. Look on his site and you will find such a motional fb circuit as I described decades ago.
THx-RNMarsh
I always regret being rude, except for when being patronised. Even then I can change my mind about someone. I look for the good and accept that not much can be done about the bad. And there are some here in this thread who I keep well away from.
If you can forgive me for saying so, I don’t exactly feel that you have an altogether good opinion about me.
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It maybe a non issue to traditional thinking as it applies to speaker design. However, back-emf can be used to lower the drivers distortion at resonance in a better way than traditional spkr/box design can do alone.
First, understand it, try it, listen and measure. you will like it.
THx-RNMarsh
===
Regarding a clean break or arc-free break on contacts --- see mercury wetted contacts. Very fast and 'clean' disconnect.
To prevent arcing... speed of disconnect is important. In the HV world.... to get the distance needed to break contact without arcing the compressed air-blast breaker is used. It literally blows or blasts the contacts away from each other.
-RNM
Joe's schematic that he talks around has none of this. This only adds confusion. I have not seen motional feedback discussed outside of actually sensing motion or position, again more opportunity for confusion.
Mercury wetted contacts worry me, because of previous experience with them. They seem to make the sound more 'forgiving' compared to silver on silver contacts. You, Richard, may remember when we tested them at Peter Moncrieff's place, about 40 years ago, as they were in the Spiegel ABX box. That is why I was so interested in your CAP DA test set-up. There were the CLARE mercury relays! I hope that you take that with you, when you go. Personally, I would love to test those CLARE relays today with my better test equipment that I now have available.
When it comes to making measurements, why bother, unless you can really prove something? Ears work better than virtually any test equipment, so I usually listen first, THEN, if possible, try to measure why something sounds the way it does. I did extensive measurements in the past, but I don't have the same 'energy' to bother, anymore. I would rather read textbooks, etc.
When it comes to making measurements, why bother, unless you can really prove something? Ears work better than virtually any test equipment, so I usually listen first, THEN, if possible, try to measure why something sounds the way it does. I did extensive measurements in the past, but I don't have the same 'energy' to bother, anymore. I would rather read textbooks, etc.
Thanks, I was wondering about that, thought it might be some strange accepted terminology since no one had mentioned it before.
Especially, in the "open session", sighted test. Been there and really regretting the years I spent with that approach. However, it is possible to train and avoid to some degree the prejudice and bias connected with circuit topologies etc.
Hmm... I don't know exactly. Opinions of that nature are not purely based on logic, and I don't have a strong feeling about it. I like you better when you are not rude, that's the main thing. Happy to have you here and participating, sorry if I haven't made that come across.
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I wish Jan all the best, but think that the impact factor overall isn't high enough.
Of course, 2017 is not that old, but one could argue that the publication about this stuff shows that it is of interest (maybe because it is not part of the standard process).
The Panasonic is fine (a few others are too) but IMO one will only choose/find the Panasonic (or one of the others) if he already is aware of the problem, as there are/were literally hundreds of "signal relais" without any hint to the problem given in the datasheets. Ok, could happen by accident too.....
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I like it better when I’m not being rude, too. Not entirely sure that being online always brings out the best in people. Perhaps it is from my roots where being sarcastically rude can often be very funny to the person on the receiving end - it shows that you actually care. OK, we can be friends now.
I hope we can agree that this something different?!
As said (implicitely) before, I do ask for rephrasing, if I think/feel that I didn't understand the question.
Seems no one knows and even when you show them, they just go right past it. Must be they dont understand what was said or done.
Joe is talking about back-emf. I am also and using it in a way to lower driver output THD. Seems like something we all might like to see happen. But, nope. Amazing to me.
THx-RNMarsh
I wish Jan all the best, but think that the impact factor overall isn't high enough.
Of course, 2017 is not that old, but one could argue that the publication about this stuff shows that it is of interest (maybe because it is not part of the standard process).
The Panasonic is fine (a few others are too) but IMO one will only choose/find the Panasonic (or one of the others) if he already is aware of the problem, as there are/were literally hundreds of "signal relais" without any hint to the problem given in the datasheets. Ok, could happen by accident too.....
Come on Jakob!!! Scott worked in semi's his whole life and these kinds of relays are used all over in small signal ATE. I worked in power mosfets for 10 years (business and marketing) but I've seen enough ATE test setups in the assembly centres full of small signal relays switching uA and low Voltage signals without any hitch - and in the Philippines, Hong Kong and Guangdong where its hot and sweaty most of the year.
Yes you read the stuff (including the obviously wrong part) and make no comment, amazing actually stunning.
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