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July 16, 2011 / consort3

My new amplifier

My new amplifier I like the way they mis-spelled Presence. I am disappointed that there is no Tremble control or better still Knee Trembler control

Takes me back to Tripletone amps whose unique selling feature was a ‘middle’ control but I think they called it presence.

No, actually they called it middle.  Guitar amps have presence controls apparently. One of the early Amstrad amps had a middle control too. That was when Amstrad was based in Ballspond rd Hackney, actually Ridley rd. The service department was like a vet’s surgery with people waiting with their pets on their knees except these pets were amps! Alan Sugar has come a long way……….. I think the Amstrad was the Integra 4000 which seemed to be a copy of the Metrosound ST60, both having  slider controls and a Middle control. Good history of Amstrad here:

http://www.amshold.com/social_media/The_Amstrad_Times.pdf

I am ambivalent about Alan Sugar, I do not like the format of his TV shows  or his TV persona but I am reading his autobiography and it would be inspiring to budding entrepreneurs. “What you see is what you get” He had a cheeky charm in his early days and deserves his success. I bought a plinth and cover for my turntable back in 1970 which was probably made by him. He invested a lot of money in an injection moulding tool for the covers which enabled him to make them a lot cheaper. There is a good story in the book about why the knobs on the Amstrad CB radio are the same size as the spare buttons in his Japanese hotel room sewing kit!

The story of the first Amstrad computer the CPC 464

http://www.theregister.co.uk/Print/2014/02/12/archaeologic_amstrad_cpc_464/

Alan Sugar was a customer of NEC semiconductors whose salesman was one Alan Shaw. Mr Shaw bought the ailing Harbeth speaker company from Dudley Harwood 30 years ago and made it successful. Alan Shaw is another inspiring entrepreneur.

Interesting article on distortion from the valve era:

http://www.roger-russell.com/truth/campbellsineward.htm

Here is a technical piece on the design of a valve amp including the transformer winding which tended to be a commercial secret:

http://www.audiophool.com/Misc/50W_1954.pdf

3000 watt amp by the same author, the filaments take 21A at 7.5V. The 4-1000A tube can be used as an oscillator, modulator and amplifier, and, in poorly designed equipment, they have been known to operate as all three simultaneously! Note that the amp only does 400 to 4kHz and has lethal voltages Link here:

http://www.audiophool.com/Misc/3Kpdf.pdf

The famous Williamson amp from the same era, this booklet was issued in 1952
Williamson 1952 The Williamson Amplifier

2,500V op amp!
http://www.apexanalog.com/apex-products/pa99/
3400 Farad capacitor
http://www.maxwell.com/products/ultracapacitors/k2-2-85-series

Make your amp more efficient with envelope tracking

http://e2e.ti.com/blogs_/b/fullycharged/archive/2016/03/24/make-your-audio-amplifier-more-efficient-with-envelope-tracking

Where I come from we used to call this configuration a Cherry Pair after an article by E.M Cherry. Its good for video amps

staggerda

According to this article, it is a Staggerda configuration

http://www.edn.com/electronics-blogs/edn-s-60th-anniversary-collection/4442586/Audio-lectures-from-1960–High-frequency-transistors

Smart microphone

http://www.planetanalog.com/author.asp?doc_id=564579&section_id=3369

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