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I did an interesting experiment today trying to learn if those Melquiades driver tubes have even gain. The Russian tubes are notorious to have very widely spreading specification, so….

I took 14 6E6P. Some of then were new, some used and some violently used. I stack them one by one into the single-stage Melq, drove it with 100Hz loaded to 12R and measured with my db meter the differences between each tube. To my satisfaction only one of the tubes had after 10 min of burning .25dB difference in gain. It is 1/4db among the 14 tubes… VERY NICE.

This is very good sign an after the 6C33C it sounds like a blessing….

Now are the problems. To my great dissatisfaction Lundahl does not has the transformers that I need. I might used some of the amorphous Lundahl transforms but it for HF channels will not be an ultimate solution.  Not to mention that sine I will be building in the single-stage Melquiades INSIDE the Macondo frame the side is matter and for the given project the overly-large Lundahl core is not a virtue. (Lundahl does not do low impedance small transformers)  I will summarize my install draft what I might need, perhaps someone would point me to an interesting direction.

So, the single-stage Melquiades will need the following transformers: (all channels will drive 30mA and all transformers are 12-13 to 1)

1) 100-500Hz channel high-passed at 50Hz: amorphous core 100-120mA (with possible double tubing), with relatively high primary inductance. I migh use Lundahl 1623A.

2) 500-1000Hz channel band-passed at line-level, amorphous, with moderate primary inductance. I migh use Lundahl 1623A with 200-250mA gap but I would prefers to have 50-60mA with less core mass.

3) 1000-1200Hz channel operating full range, amorphous, with low turns on primary and good size core to be able to care full range though the amplifier. I should be gaped for 50-60mA. I have no prospects at this point.

4) 12500Hz and up channel operating high-passed at 12500Hz, amorphous or powder (or air?) very small core, with ultra low turns on primary. I should be gaped for 35-40mA. I have no prospects at this point.

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