John Curl's Blowtorch preamplifier part III

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What on earth are you talking about Dan, have you finally lost it entirely?
LOL, what do you mean finally? :rofl:

but as you've cited your claims, there still are "snake oil" and "sales pitch" present.

"snake oil" has a meaning and "sales pitch" has too, and therefore you have the obligation to bring evidence for the "snake oil" in my posts (and of course for the sales pitch too).
It should be obvious that it is not sufficient evidence if you find other people sharing your opinion.....
You should put the two quotes you separated back together so that they show as I've written, "Oh, that "research". Why should anyone fall for snake oil sales pitch that Jakob(x) tried over at Hydrogenaudio and already got exposed for what it is?" and then retry (not holding my breath) to understand in the context of the entire sentence because that's what happened over at Hydrogenaudio.
It might be what "krabapple" believes, but as said quite often before, believes are not the same as facts. Therefore I regularly brought to mind Feynman's "punch line" that the easiest to fool are yourself.
Your attempt to promote your audio business was visible and what krabapple did was to spell it out publicly.
Any refusal to learn about propper reasoning and bringing up evidence will just lead to more fooling yourself in the future.

Certain cult sections are, despite Feynman's warning, more interested in "cargo cult science" than in real science; if you still want to belong to this group, I'd say it is unfortunate, but you still have the obligation then to mark your claims as opinion but not state it as fact.

As we both know, you did not ask me to send you the publications about the scientific evidence (although I regularly post the offer to supply interested members with copies - under the fair use rule for educational purposes), and btw krabapple didn't either, but even a layman should be able to finally understand that pointing to flaws in methods and test protocol and analysis will lead to _better_ tests.

Therefore even a layman should be able to understand that pointing to flaws is something different than "discrediting of DBT" , but of course the layman might be more happy to further fooling himself.
And your attempt continues.
It doesn't work that way; it's your opinion based on lack of knowledge about sensory testing (and of course statistical analysis) and refusal to learn.
As said before if you mark it as opinion, that's freedom of speech; if you state it as fact you have to bring up evidence (which you obviously can't).
And the denial continues. Very persistent indeed. Such is the case when money is involved.
 
Don't forget the series RC Zobel network in the amplifier; its impedance above 100,000 hertz is less than 20 ohms.

On the back emf it would be after the inductor so it would be reasonable to assume no significant back EMF above the audio band makes it to the feedback terminal. But lacking actual measurements who knows? (Who cares is another issue. When have something going on similar type setup, I may actually look. "Can't hurt.)
 
Okay, let me do a truly shameless self promotion! Anyone needing a sound system for a public space with more than a few thousand seats, please give me a call! (Will do local churches of any size.)

Even more shameless do a google search of sound system installation Pittsburgh and see if you can find my website!! :) (Do let me know how bad it is...)

See that is what self promotion should look like.

BTY the TI guys were here and mentioned that it looked like mentioning pro audio products here resulted in a wide spread of knowledge.
 
Max, Two of the the best EE's I ever knew are females. Also I know some damn good recording engineers that are female. You need a transporter to 1950.
Hi Robert.
I am not dissing women in any way or form, what I am dissing is a grown man acting like an 'old woman', with never ending sly comments, judgements and criticisms of others and rarely anything positive to say.
As for respecting and liking women, that's the way I was brought up.
I especially like this quote from Eleanor Roosevelt.

“Great minds discuss ideas; average minds discuss events; small minds discuss people.”
 
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Joined 2008
Okay, let me do a truly shameless self promotion! Anyone needing a sound system for a public space with more than a few thousand seats, please give me a call! (Will do local churches of any size.)

Even more shameless do a google search of sound system installation Pittsburgh and see if you can find my website!! :) (Do let me know how bad it is...)

See that is what self promotion should look like.

BTY the TI guys were here and mentioned that it looked like mentioning pro audio products here resulted in a wide spread of knowledge.

I found it.
I wouldn't exactly call it "Pro-Audio"

Welcome to Edward Simon & Co. For over forty years we have been establishing the cutting edge in large sound systems.

Recent work:

THE GATEWAY CLIPPER

"THREE RIVERS QUEEN"

The Gateway Clipper Fleet offers riverboat cruises that feature dining, guided tours, dancing, live music, and other entertainment. We recently had the opportunity to replace the sound system on one of their boats, the "Three Rivers Queen". Since they offer a diverse set of programming they needed a sound system that was easy to operate and able adapt to the needs of each type of cruise. Their existing system was clunky to operate and was unable to accommodate all of the configurations they desired. The speakers had also been severely weather-damaged and were not functioning properly (some of the speakers were not even exterior speakers to begin with). We were able to provide them with a new system built around an Ashly amplifier with built-in DSP and a remote interface which allows them to change between the different configurations they need. We also added a weatherproof mic jack on the upper deck for tour guides, a mic jack on their second deck, and a mic jack in the pilot's cabin. We replaced the mismatched speakers with Community R1.5 weatherproof loudspeakers. Now, the "Queen" is easier for the crew to operate and is properly outfitted for the harsh conditions that it faces on the water.

:rolleyes:
 
dan... Try 100 Ohm non-inductive.... Farnell #551-594 (TO220) for cable term of 90-100 Z cable.
Thanks Richard.
I used these resistors MP930-100-1% Caddock | Mouser for production and some Vishay 1/2w on my Quads at home. It does usually seem to make a significant difference.
Thanks Demian.
Think about how electrons flow in a metal film! On the surface and only to a few microns deep into the metal. This creates thermal hotpots due to manufacturing defects and impurities. People think MF's sound bad in some applications because of the resistor inductance arising from the helical cut in these resistors used to achieve exact resistance, but it not - its the hot spots and that leads to constricted highs and loss of dynamics at HF.
Think I'm talking bs? take a look at this
http://www.jetp.ac.ru/cgi-bin/dn/e_074_01_0088.pdf where the math proves it.
Good info, thanks.
The link is not working for me ?.
The correct solution is a Ayrton-Perry wire-wound resistor (see here Ayrton& - Wikipedia ). Mills do the best ones (great resistors for CFA feedback networks BTW - I measured the L on the 1k 10W that I use at 36nH which is about the 3x a straight copper track on a PCB).
Details here Vishay Mills - Vishay Brands - and they are available from mouser and DK.
Good info, thanks.
Now, I'm letting all my techniques for good sound out here, so you should respect me (and that includes you Syn08).
I have always respected you Andrew, and thanks for your secret sauce. :cheers:
 
100 watts at 8 ohms is 28.3 volts. 100 watts into 94 ohms is 8.5 watts. As there is no less than 10 dB of headroom two 1/2 watt resistors in series can handle this.
Actually for decent reproduction headroom is more often 20 dB. However there is a bit of surge rating required so a .085 resistor would fail.
Thanks for the confirmation, cool how maths can model the real world. ;).


The interesting issue is the settling time of the cable and effect on feedback. Some loudspeakers will have very high impedance above 100,000 hertz and that may affect some audio power amplifiers feedback settling time. (Don't forget the output inductor in the amplifier.)
The termination R is about settling time and loading induced RF and reducing RF ingress........Bateman mentioned RF ingress getting through output L/Zobel and getting to feedback point.
 
Hmmm. :scratch2: Anybody think Evenharmonics might be in the audio business? You know, manufacturing ABX systems? He is always trying to promote his audio business on the sly! :nownow:

I think he's the mirror image of the neurotic audiophiles you segment. And the fact that he puts a black eye to scientific rigor with his logical fallacy one liners drives me bananas*. Then again, I've taken him to the task on ABX and the fact that (s)he couldn't tell me how to design an experiment and build in controls told me enough, much less have an a priori understanding of end points and how the statistics were going to be calculated (i.e. no cheating the stats after the fact)...

* In most industries, the very folks that are in the business of making XYZ product are going to be the ones with the greatest scientific knowledge about the subject. Because most fields you actually have to deliver a performance criteria. Luxury goods (most of audio, IMO), some of which are so from an excess of engineering, some of which are so from a lack, may or may not fall into that category. We see both kinds here on this thread--but it does sadden me that you don't get the idea that folks are having fun doing this stuff.
 
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