60W EL34 tube amp, in: Quattrocose, February 1967 🇮🇹

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modman
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Post by modman »

Complete article in pdf:
Quattrocose 1967_02.pdf
(1.41 MiB) Downloaded 122 times
Quattrocose 1967_02 04.jpg
Quattrocose 1967_02 03.jpg
Quattrocose 1967_02 bom.jpg
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ppluis0
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Post by ppluis0 »

For the young people here at the forum, the first picture is equivalent to a solid state veroboard 8)

For the elder members:
it's strange that inside a feedback loop (from output transformer to a third amplifier stage) the designer incorporate a Baxandall tone control... :roll:

What do you think ?

Cheers,
Jose

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bmxguitarsbmx
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Post by bmxguitarsbmx »

Good eye Jose. That is strange to have an eq inside the feedback loop. Modifing the frequency response of the open-loop gain that then the feedback loop will try to correct seems suspect. My guess is it would cause user confusion. On the other hand, if you wanted less error correction in the top end and more error correction in the low end (or vis versa) it may be useful? Extra Phase shifts inside a feedback loop is another potential problem though too.

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Manfred
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Post by Manfred »

Great, i love these wiring diagrams, wiring meets art. :thumbsup

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Guilherme
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Post by Guilherme »

The Marshall 200W tone control is inside the feedback loop.
https://el34world.com/charts/Schematics ... d_200w.pdf
It always seemed strange to me...

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