Talk:Quad Electroacoustics

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rewrite of 27 June, 2006

The article's meandering structure and lack of objectivity has been addressed in this rewrite. I did not want to slap a "weasel word" warning on the article. I found the previous version far too glorious in praise for Peter Walker and QUAD products; Description of each product was occasionally too detailed.

Text on products is now in the form of a chronological milestones chart; much of the overdosed praise has been removed. Someone would need to go through this list and ensure that the major milestones are there and correct, and remove those which are only of passing interest.

I feel that "closest to the original source" is more of a mission statement, and I would suggest that someone added an overview of how this translated into the design philosophy behind each category of product to make the article more relevant and interesting. It may have existed in the previous version, but this did not come across at all.

Although QUAD was clearly a pioneer in UK ampifier circles, it has largely lost the leadership to more modern UK and US competitors. Its role is therefore strictly historical. Cost at launch of a product is meaningless without comparisons; the type of valve used is of dubious interest to anyone except the most fanatical tube enthusiast. I also removed the paragraphs dealing with the amplifier naming convention, as this would be of minor or no interest to those who merely wanted to learn about the company and its landmark products.

Its reputation today is associted with the ESL, thus I added a refernce to QUAD being synonymous with the electrostatic LS accordingly. It is only my personal perception. Notwithstanding, I felt it more appropriate to leave the detailed descriptions and strengths and weaknesses of the electrostatic design to the page about Electrostatic loudspeakers. Ohconfucius 07:29, 28 June 2006 (UTC)[reply]

VFD tag

Someone put a VFD tag on this page at the same time as I moved it here from Quad (audio). I'm not sure quite how to resolve this. Sorry if I've trodden on anyone's toes. Spliced 16:49, 12 August 2005 (UTC)[reply]

QUAD

There is a duplicate article QUAD that should be merged here. I have tagged and listed these. Q Q 02:34, 18 December 2005 (UTC)[reply]

This is incorrect

"The rough capability of the amplifier can be seen in the names. For instance, the 303 uses a 30V power supply and can supply 3A. The 405 uses 40V and can supply 5A etc."

The 303 is a single ended arranged regulated power supply amplifier with rail voltage at 67v its midway voltage namely the junction of upper and lower transistor triples is approximately 33v.

The 405 uses a 35VAC Dual rail supply resulting in approx 52v DC negative and 52vDc positive rails

The real reason for naming of the amplifiers ,I am currently researching and will report back here 61.68.169.28 14:28, 17 February 2006 (UTC)[reply]

I have received a reply from Quad themselves which states The 303 amplifier was named 303 as it produces 30 volts peak 3A output. The 405 amplifier was named 405 as it produces 40 volts peak 5A output. The Quad II was just the next number on from the Quad I.

The way the existing text reads there is confusion that a DC power supply voltage is part of the naming - hence my raising of this question, when it is in fact the peak AC voltage value developed expressing the maximum voltage attainable from the output devices and including a current rating. - as such I am posting a correction.61.68.171.131 13:00, 22 February 2006 (UTC)[reply]

Corrected distortion measurements Quad 405

I posted a correction to Quad 405 distortion measurements.

Although text concerning amplifier description is just there,- it needs a bit of tarting up - mention should be made of the 405 circuit using a bridge configuration solved by the equation

"Z1/Z2 = Z3/Z4 where Z4 was a sensing resistor. P.J. Walker's

unique contribution to this thought was that this equation held very usefully if you made Z3 and Z4 reactances instead of resistors." quotation interview with Mike Albinson designer. http://www.quadesl.org/Album/InterviewsReviews/MikeAlbinson/mikealbinson.html

Mention should be made of conduction classes ie it is a Class C amplifier - output dumpers ( Transistors ) controlled by a Class A amplifier fed initially in the case of the 405 by a inverting op amp 61.68.169.28 14:57, 17 February 2006 (UTC)[reply]

"Straight wire with gain"

I do not believe this statement: "... and insisted that all amplifiers sounded the same when used within their capabilities ..."

Can you provide a citation? **

I suggest replacing this statement with Peter Walker's widely quoted statement that the ideal amplifier should be like "a straight wire with gain". [1]

I remember an article in a Hi-Fi mag saying that one test for amplifiers used by Quad was to attenuate the output (driving a load), differencing the attenuated output and the input (phase shifted if necessary), and nulling and amplifying the resulting error signal. The error signal is the noise and distortion that is added to the signal by the amplifier being tested. Different amplifier's distortion sounds more or less musical or unpleasant. The transistor Quad 33/303 system produced significantly lower noise and distortion than the valve Quad 22 / II, but the valve amp's distortion was not unpleasant.

I do not think the statement about the speaker wire thickness should be quoted, as it is presumably out of context, and hardly relevant. Speaker cable impedance obviously has far more effect on 4 ohm speakers driven by high power amps, than with Quad's 16 ohm ESL driven at lower powers, that the statement presumably refers to.

How about: "... and insisted that ideally all amplifiers should sound the same when used within their capabilities, famously introducing the concept of the ideal amplifier as being like "a straight wire with gain". GilesW 13:26, 21 July 2007 (UTC)[reply]

There was an article in Wireless World around about 1979 that said that Quad amplifiers were subjectively perfect; that was justified by a similar setup to that described above - the amplifier in line with a attenuator so that the net gain was zero. listeners would hear music passed through this and try and spot when the setup was replaced by wire; they couldn't tell - although you might have thought there had been some clicks when the switches were thrown.

Apepper (talk) 18:34, 19 December 2007 (UTC)[reply]

A note evidently written by Quad staff and titled "QUAD COMPARATIVE AMPLIFIER TESTS, TUESDAY 21st MARCH, 1978" posted on Yahoo Newsgroup quadhifi, 6 Nov 2011. It includes the statement "All this is not to say that all amplifiers are the same. There is a considerable sprinkling or amplifiers - in all price ranges - which so change (distort) the quality for good or ill." It goes on to describe listening tests where an expert listening panel detected no statistically significant difference bewteen Quad II, 303 and 405 amplifiers. Martin A

error in "date founded"?

The side panel states "Founded September 14, 1978".

This is an error surely?

77.204.155.195 (talk) 11:29, 11 December 2011 (UTC)[reply]

I've changed the date in the side panel to match the founding date in the text, 1936, which is confirmed on the company's website. --Snogglethorpe (talk) 07:05, 18 December 2012 (UTC)[reply]