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REN904 for linestage?

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bequerel

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Joined 2003
REN904 (or similar) is an audio triode specifically made for transformer coupling. Would it be a good candidate for a linestage with a 30k:500 line output transformer, you think? The gain is approx 30x.

Vf 4
Af 1
Va 250
Vg -3.5
mAa 6
ra 12,500
gm 2.4




REN904a.jpg
 
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kevinkr

kevinkr

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kta-hifi.net
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Plate resistance is pretty high for use with full audio bandwidth transformers, building a 30K transformer that is reasonably flat over a range of just 20Hz - 20kHz would be very difficult.

Tubes with an rp half that of the REN904 or less would be much easier to source a transformer for.
 
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pieter t

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kevinkr;2478657) Tubes with an rp half that of the REN904 or less would be much easier to source a transformer for.[/QUOTE said:
In my experience tubes with an Rp around 6-7k (6SN7 for instance) are about the limit with inductive coupling. Plate chokes and dedicated 1:1 transformers will do, but everything else becomes problematic. The combination of high Rp and winding capacitance will result in loss of treble and/or early HF phase shift.
Click to expand...
 
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pieter t

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Bequerel,

Data of this transformer seems to be good, but in what regard?
It has some 240H of inductance, needed for bass response.
Frequency response is indicated to be -3 dB at 10 Hz.
But the problem, without doubt, will be "at the other side" of the spectrum.
Don't expect audio treble with a 12k Rp tube; we can't cheat nature.
 
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