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RE: Hello 'T', off topic...

Posted by Thorsten (M) on June 5, 2013 at 10:57:10

In Reply to: Hello 'T', off topic... posted by Ivan303 on May 27, 2013 at 08:19:51:

Hi,

My "favourite" 300B is as follows:

TJ 300B Mesh Plate
350V/60mA Operating point (means around 1.2K cathode R for self bias)
5-6K Load impedance (mismatch the transformer - treat 4R output as 8R)

This overall reduces output power (you get around 7 Watt) and moves the sound into the direction of the 45.

Add a D3a as driver stage (Resistor Load 22K is ok, CCS or Choke more better; bias - choose your poison aim for 170V/10mA appx.)

Sadly consistency at TJ has been slipping, so only buy them local, tested and selected by the seller and with a decent warranty.

If you want traditional WE Style Sound keep the 350V/80mA/2.5...3K and get either WE Replicas or Svetlana's. Sadly my experiences with the Svetlana's in terms of longevity has not been great, so see above for sourcing.

There are a lot new "brands" and "models" of 300B out there, which to me look all like Shugang/Guagang/Sovtek/Svetlana fayre on the inside (or rebranded TJ), gussied up and sold at obscene markups. So I never tried them...

I did like the Vaic/EML tubes I tried, however there are issues with supply/consistency/warranty, so only buy local with solid warranty.

As an aside, if you can live with low power, I quite like the recently introduced Shugang/Guagang 2A3B (single Anode) which is one of the few 2A3 I actually like. Sticking them into a Billie suitably modified (I like the old DC coupled JC Morrison design from the Fi Primer with 6SL7 SRPP driver) makes a very nice and inexpensive Amp.

Thor

At 20 bits, you are on the verge of dynamic range covering fly-farts-at-20-feet to intolerable pain. Really, what more could we need?

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