John Curl's Blowtorch preamplifier part III

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RNMarsh said:
Joe is talking about back-emf.
Yes, and by so doing he demonstrates again and again that he does not understand the words he uses.

Doesnt matter if there are some wrong parts. fix them for him/her.
We have tried correcting him, but he doesn't listen. Basic errors do matter, because they can be a sign of basic misunderstanding which means that deductions made from them will be wrong too. Joe is not the expert who occasionally does a typo or gets a sign wrong in a piece of algebra; Joe gets elementary things wrong over and over again and brushes away any attempt at teaching him.

How could one know that back-emf exists
Perhaps by listening to almost any basic electricity course? It is a term often introduced when discussing motors, but also arises when thinking about inductors. Joe misuses the term by lumping together anything which is not part of the DC resistance and calling it 'back emf impedance'.
 
I already have. In this thread. Resistors, capacitors and relays have all been shown. FYI some non reed relays also place a steel signal conductor in the magnetic field and have similar issues.

Barkhausen effect occurs in a changing magnetic field, not really an issue with a stable DC supply to the relay coil. It was used as proof of the existence of discrete magnetic domains. You really do seem to like discussing things with little knowledge of the subject.

Understood, no evidence to show.

I was pulling your Barkhausen leg and you got the bait. Sorry for missing the sarcasm emoticon :rofl:.
 
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.

I must admit to have no idea what part of my post (or what post) could lead to this reaction?!
I wasn't talking about Scott nor did I question the use of such relays in ATE; in fact I did quite the contrary (implicitely though).....
 
I saw and heard the new Purifi's 6.5 " woofer in a two way and it sounds excellent. Very impressive distortion figures. They really got onto something with their innovative motor assembly.

Excellent... look forward to hearing it too!

I need actual contacts. Can't speak for anyone else

Fair enough - what's getting switched?
FWIW, when my system is, ahem, finished... it's optical connections and only one source (server) so.... 🙂
 
The "FUD shouter" is back; after curing his bloody nose (and obviously eager to get a new one) . 🙂

As I meant with "in any case" "not in each and every case" there is - as usual - no reason for "FUD-shouting" ...... 😉
You really have to wonder about his motivation and mental health.

Pavel,
I suspect Thevenin and Norton would allow one to design a current drive mode crossover. It would probably be different than the common designs. But quite simply not worth the effort. Folks like JBL professional do make powered loudspeakers that at one time were a significant part of their business. I know the guys who designed the original ones. The went so far as to make the woofer basket part of the enclosure. With such a ground up design they went with voltage driven! Probably due to the experience and vast body of knowledge as to how to tweak things.

These days the bean counters prefer to buy from offshore contractors units made of conventional parts.

Now as you know there is a very easy way to avoid all sound system distortions. But it is a secret! So don't mention it.
 
DSP is simpler, really, and much more flexible and accurate.

It can be. On the other hand, DAC3 or better performing dac channels and AHB2 performance level power amplifies have a cost, at least for those who have considerations of that nature involved in their overall system design decisions.

In addition, digitally separating DSD into crossover bands is not nearly so simple. If we standardized on a distribution format of something like DXD, then used digital crossovers followed by DSD modulators it could work. Not all that cheap and easy though.
 
I just love 'open' listening sessions. That is how I compare audio products.
Yeah, is there actually any other way to compare audio products that duplicates home usage ?.

Do you ever do a comparison whilst listening to complex music?
Ummm, yeah regularly, comparisons of AC filtering, AC cables, signal cables, speaker cables, data cables, DAC's, BT transmitters, BT receivers, capacitors, resistors etc and much more......using all manner of music types, performances and recording qualities.

During this period I am very deliberately exploring system level stuff that is plug and play and representative/applicable to standard systems, I have done my share of soldering iron dependent designs, constructions, improvements and tweaks etc since forever, this is different angle of investigation.

And so how about you, what is your level and experience of experimentation and what music apart from Benny Goodman ?.

Dan.
 
Just as a matter of interest Jakob, would you consider the above FUD?

As "FUD shouting" comes right from the playbook of eristics, one has to decide if it is about "debate winning" (and not caring about what is correct) or is it about "truth seeking/finding" .

Of course these tricks are kind of fad; for some time it was to be the first who said "Dunning-Kruger", others tried to establish the method of being the first to mention "sea lioning" and for others it is "FUD shouting".

So the "FUD shouting" has no place in a honest discussion.....
 
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.
Not invented here, not important........

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.
Maybe Mr Behringer listened to you..... 😉.

psu and amps.jpg

And seeing there is discussion about electronic crossovers this is the Behringer solution....

input and filter.jpg

How is the DAC-3 sounding now, worthwhile approach/technique ?.

Dan.
 
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