John Curl's Blowtorch preamplifier part II

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Jacco,
If I actually printed some of the listing for some of these grand mansions you would wonder like I do how many bathrooms could you possibly really need, it is crazy how many some of these large houses really have. Many times double the number of bedrooms, it is ostentatious to say the least. Does anyone really need 20 to 30,000 sq, ft. homes when only two people live in them? I don't understand the thinking myself, a nice house with everything you could think of but are these people really having sleepovers with 30 or 40 people staying over night? Not only that many of these homes aren't even the primary residence, they are there a couple of days a year, it is truly sickening when people are living on the streets.
 
Does anyone really need 20 to 30,000 sq, ft. homes when only two people live in them?

Have you ever visited the Gamble house in Pasadena? Could you imagine these days the head of one of the largest corporations would build a 6000 sq. ft. house that is also a work of art? Probably not an inordinate number of crappers either. I'll be spending the July 4th holiday with nothing but a two seat "short-drop" (the host is lazy) privy.
 
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Gee Frank, that you should have so little faith ...

Karan Acoustics KA-i180 will do it just fine, at 180W/W and for around €6,000 a pop.

If you're feeling blue, a second hand Marantz 1182DC integrated, at 86W/8 Ohms, will do it as well, Anatch has already lined up a few very useful pointers on what to change. Latsly, for around €120 locally, a H/K 6550 integrated will literally shine with new caps and a changed volume pot. WARNING - highly addictive sound.
Dejan, there will always be exceptions, :). My history has been that I've listened to systems with conventional pots, and I can hear the degradation caused by the wiper mechanism - and this bugs me strongly, I'm now super-sensitive to this artifact. So, my first major tweak would be to eliminate any such mechanism - one less potential troublemaker ... :D.
 
I think folks are not differentiating analog (swept spectrum, wave-analyser, etc.) from digital.
Nothing wrong with a nice bit of heterodyne analog for the purposes here.....the first audio spectrum analyser I had the pleasure of was entirely analog..........

Aside, did you know that Fourier Transform results are naturally complex numbers, even when fed with entirely real time samples? That is to say, the result includes phase info for discrete frequencies, which fact is generally disregarded or ignored for reasons unknown.........same is true of heterodyne detectors, in a very different way of course........
 
Aside, did you know that Fourier Transform results are naturally complex numbers, even when fed with entirely real time samples?

Euler's equation is your friend, I can say that forced once to work through SSB with all the tedious algebra and trig identities.

BTW Lucky can you figure out the boustrophedonic IIR filters in the Weiss parametric equalizer I don't see how any linear phase filter filter can have no pre-shoot i.e. causality in the exact sense.

George knows what it means. :)
 
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The point about the PC speakers, and now just using a laptop, relying on internal speakers, is understanding the common factors, the core of what needs to be optimised in every situation - there is a continuum in what can be achieved from the highest to the lowest, in nominal capabilities.

Key factors in what made the original, "real" setup work - which I have already described many times - were:

Simplicity: there was only a high end CD player, the best Yamaha you could get in the mid '80s, feeding a nominally muscular Perreaux power amp, and B&W bookshelf speakers. No source switching, or extras.

Integrity of the chain: there was no analogue volume pot - the Yamaha did proper digital volume control, all the components were hardwired together, every connection that relied on a pressure contact, metal to metal, was modified to be airtight by soldering - from the power lead in to the terminations on the speaker drivers

Stabilising of the speakers: this were set up to be as rigidly locked to the floor structure as I could, effectively the carcase vibrations were heavily damped

Long term conditioning of the electronics: this meant leaving everything on 24/7, the CD player especially was sensitive to this - from cold it took ages to develop the best quality

Strenuous conditioning of the speakers: feeding them highly energetic material so that crossovers and driver suspensions were at their best.

I didn't decide to do this from day one - each step occurred because I had a thought, experimented, or just noticed a behaviour pattern; the SQ kept improving with each iteration.

The amplifier was actually the weakest link, its smoothing caps were way not good enough, and I spent long periods trying to wring more from them as is - and much later did major surgery "fixing" this.

Note that no substituting with fancy electronic parts was done, no altering of the circuitry as delivered from the factory was done - I was simply identifying what looked to me as weaknesses, and "beefed" those areas up.

This gave me short bursts of the sound that floored me the first time I heard it - and everything since has been refining my understanding of what needs to be looked at.

Thanks sharing Frank.

( re opamps: yes in my new pre I am buffering them and running the whole kabodle in class A).
 
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Nothing wrong with a nice bit of heterodyne analog for the purposes here.....the first audio spectrum analyser I had the pleasure of was entirely analog..........

Aside, did you know that Fourier Transform results are naturally complex numbers, even when fed with entirely real time samples? That is to say, the result includes phase info for discrete frequencies, which fact is generally disregarded or ignored for reasons unknown.........same is true of heterodyne detectors, in a very different way of course........
When a co-worker was looking at FFT boxes many years ago, he asked "so these are real-to-real?"

The salesman said, "Well, we actually prefer cassettes."

<rimshot>
 
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Joined 2005
Have you ever visited the Gamble house in Pasadena? Could you imagine these days the head of one of the largest corporations would build a 6000 sq. ft. house that is also a work of art? Probably not an inordinate number of crappers either. I'll be spending the July 4th holiday with nothing but a two seat "short-drop" (the host is lazy) privy.
My very old friend Crosby Doe is a realtor who specializes in "architecturals", mostly in the Southern Calif. area. He used to send me glossy trade magazines full of McMansions, with a few pages within devoted to the properties that he and his associates handle. Of course the McMansions were almost all in hideously bad taste. As one writer said of a Texas multimillionaire (when that was a lot of money) who had tasted a bottle of a case of some TBA he'd just gotten at auction and stated "Tastes like grape juice and honey", "The money can buy the wine but not the palate". Of course this extends to homes too.

Doe finally started his own quarterly, and I get those now. The likelihood of my ever buying another house is negligible, but the beautiful ones are fun to see.
 
The power buffer is not in the loop of the preamp. The power buffer has local feedback only.

pre with dial-in gain
preamp buffer.gif


and then ... PwrFllwr !!!

PMA Power Follower.jpg

from re: ol' skul!'
orig:

EL orig PWR BUF.jpg

;)
 
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diyAudio Member RIP
Joined 2005
At the risk of offense being off topic, we serve most reds too warm and whites too cold.

So it might well be that a fine wine might be better cooler than, say, room temp. But this can be done with ice or whatever as the coolant, but isolated from the wine as a liquid.

Or optionally you can make ice cubes of the exact wine beforehand, and preserve them for use as may be desired.
 
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RTA history -

RNM,

The first DIY RTA was in Popular Electronics September 1979. It was a kit. The unit is still in production but no longer a kit as the Goldline ASA10B.

So the first RTA's were multiple filter based, the earliest used LC filters and the display was a CRT using a multiplexer to show all the filters.

ES

You are very close to being the grand winner ! It was 1977. Gold line and others appeared afterwards everywhere overnight.... led bar graph displayes quickly followed rather than scope crt for display. How do I know?

See attached for the author -


View attachment RTA part 1.pdf


I had been making speaker and room decay, reverb and response curves using sweep oscillator , mic, mic premp and a strip chart recorder using thermal paper. There had to be a better way. I did all the designs' conceptual work, Bob Jones, a co-worker at LLNL did the circuit design details/pcb and made it work. he wrote the article on design part and pcb. I did the applications part and added some info i learned from the RTA and mic response characteristics. After this consumer RTA, the rest is history. Today for <100 dollars you can get a 1/24th RTA.

It was called a "Real Time" analyzer because now you could see the whole audio frequency response and any changes anywhere in real time.


THx-RNMarsh
 
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Frank,

On pots in general - I couldn't agree more, not after my own experience of what changing just one can do to a modest device, turning it into a class act. With current prices, an ALPS Blue pot is hardly a big expenditure, and even their Black Beauty is not beyond reach.

Ditto for mechanical switches.
 
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