John Curl's Blowtorch preamplifier part II

[john curl]

Actually, the 2300 was AUTOFORMER coupled. A small, but interesting difference.

[wahab]

Originally Posted by kevinh

IIRC the 2300 was a 300W mono amp which was transformer coupled.

Wasnt it a stereo 2X300 ?...

McIntosh Amplifiers Part 2

[john curl]

Yes, but it could not be MORE than 300W in stereo, whereas modern amps often give more power into lower impedance loads. The 2300 will not do that.
For example a single JC-1 will do more than 800W into 4 ohms. The 2300 in mono would give 600W into 4 ohms, or any other impedance. This is because of the use of the autotransformer. The actual drive impedance might have been 2 ohms or less, in actuality. This can be determined by the +/- 40V supplies that the power amp used for the output stage. We did not particularly like the 2300, but they were rugged, dependable, and available.

[kevinh]

The bottom line about design and engineering in general is specifying what is and isn't important. So what measurements correlate with how the ear/brain system processes the music and of course which don't matter. Engineering is a process of making trade offs since nothing in the real world is perfect. When an engineer creates a specification for a piece of equipment (if the marketing guys let him ) it is defining and prioritizing what is important and what isn't so important.

Is it the goal to get vanishing low whatever spec, yeah but not if it comes at the expense of another parameter that is more important to the goal of the project. If the goal is to make the best sounding piece of equipment the designer is tasked with determining which specifications take precedence and which are secondary.

Then there is the issue that no two people hear things and prioritize things exactly the same way either aesthetically or musically.

So we make our choices. Components and topography.

To paraphrase CS Lewis if the devil can keep you from asking the right questions he never has to worry about the answers.

[Bonsai]

Very nicely put!

[Bodyslam]

Originally Posted by wahab

They play in front of the speaker s wall , so unless the performance
was in play back, wich wasnt the case , they had to use extremely
notching equalisations to tame down the inevitable and huge acoustic
feedbacks..

One of the interesting points of the Wall of Sound system was the differential noise cancelling mic arrangement that they used so they could be in front of the speakers and not get feedback. So no, they did not rely on notch equalization.

There were two omni mics close enough together to be sampling the sound field at effectively the same point. They were combined with reverse polarity, so most of the signal cancelled. When the vocalist stepped up to the pair, he sang directly into one, so there was effectively no cancellation. It may seem unlikely, but the system actually worked.

[Chris Hornbeck]

The microphone system was brilliant, but wasn't used for long. It effectively sampled a pressure differential between the diaphragm pair, giving a "phasey"ness.

IIRC the intent, beautifully achieved, was to put performers and listeners into the same sound field. Giants walked the Earth in those days.

[gk7]

I just want to say that I believe that many people read this thread, just because there is a lot to learn from successful and experienced audio developers like John, Charles and others.
(And I wonder why people who deny that there are audible differences in high end design participate in in a thread called "Blowtorch preamplifier" at all...)

[sottomano]

Originally Posted by gk7

I just want to say that I believe that many people read this thread, just because there is a lot to learn from successful and experienced audio developers like John, Charles and others.
(And I wonder why people who deny that there are audible differences in high end design participate in in a thread called "Blowtorch preamplifier" at all...)

100% Agree.

The successful (over decades!) in the marketplace of high quality audio claim things, and those which are either not in this market or not successful are denying.
Putting down their succes solely because of good marketing, bribes, exxagerate prices or other similar things is cheap.

[ThorstenL]

Hi,

Originally Posted by gk7

And I wonder why people who deny that there are audible differences in high end design participate in in a thread called "Blowtorch preamplifier" at all...

The charitable interpretation is that they feel the need to protect the poor ignorant souls reading this thread from being taken in by charlatans, snake oil merchants and the like, who try to convince these poor "marks" that actually all gear does not sound the same and try to somehow take these poor ignorant "marks" money. In other words they are debunking fraudulent claims and protect the consumers from evil schemers that try to become millionaires by peddling stuff that does not really work.

Though truth be told, how this scheme of extracting fabulous wealth from Diy'ers is supposed to work is a mystery to me, making money of DIY'ers is hard work...

The less charitable interpretation is that they have somehow conceived that those who do not comply with "all gear sounds the same" philosophy are having some kind of fun trying all this interesting stuff, fun they are constitutionally incapable of having, so they try to spoil that of others, on the principle that "If I'm not enjoying myself I don't see why anyone else should be having any fun!".

I shall leave it to the readers to decide which rings more true.

Ciao T