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Old 27th Nov 2019, 9:10 am   #11
Alan's MagicEye
Tetrode
 
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Join Date: Sep 2017
Location: Luton, Bedfordshire, UK.
Posts: 53
Default Re: Building a 5 valve A.C. amplifier from scratch

Please forgive the further post and at the risk of harping on about it, the power output and spec. for the Zen are presented here as an extratact from a review

"The Zen is a small, simple, stereo, vacuum tube power amplifier. It is a single-ended design with output tubes wired in triode mode. RMS measurements of the Zen indicate an output of 2.4 W/channel at 8 ohms impedance.
The owner's manual states that the Zen will reliably drive speakers rated at only 2 ohms. Additionally, the two channels of this amp may be wired in series with both channel inputs linked (instructions are included with the owner's manual) that will allow it to be used as a monobloc amplifier with 8W to 9W output. The frequency range of the amp is given as 30 to 20,000 Hz at ±1.5dB or 25 to 25,000 Hz at ±3dB. The Zen Triode measures 15 x 25 x 16 cm, and weighs about 4.5 kg (10 x 6.25 x 6 inches, 10 lbs).

The Zen uses four tubes: a single Svetlana, 6N1P, dual-triode tube in the driver circuit, one Philips 5Y3GT rectifier tube, and one, Svetlana SV83 output tube for each channel. Unlike some single-ended designs at the lower end of the price spectrum, the Zen uses no negative feedback.
Retubing this amplifier will cost as little as $30.00 USD. It should be noted that the driver and rectifier tubes will last for years in normal use; only the power tubes will require regular replacement. Both power tubes in the Zen can be replaced for about $10 USD, no biasing or matching required. Cheap tubes are a good thing with this amplifier as Steve Deckert, designer and builder of the Zen and other products, has biased the output tubes on the high side to improve sound at the expense of tube life.
He recommends replacing the output tubes once per year under normal usage, or every three months, if used continuously."

Full review here at the risk of being accused of more audio silliness ;-)

https://www.tnt-audio.com/ampli/zentriode_e.html

The cheap valves were one attraction for me and possibly for anyone else considering a new valve amplifier build, for example the cost of new KT66's for the Quad amplifiers is in some cases ridiculous.

Anyway, I will be quiet now and let others comment.

Alan
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