therefore in between I'll be posting progress on my LM3886 "gainclone"

I soldered the boards a long looong time ago. So no pictures. And I don't think anyone would want to see these boards soldered part by part. pcb's are boring in that way.

The build will be quick and dirty. But still something I could "live" with. Hopefully.

I'll start today and let's see how long it'll take me to finish this article, about an easy to build and cheap amplifier, with ECL86 or with a few tweaks an ECL82 can be used. This is actually not my totally own design. It's taken from the 'Muller' Tube Manual, but I added a input stage with tone control 2 or 3-ways, depending on your flavour. And a loudness-control...
What you need accept the passive components are;
(double up all parts for a stereo-amp.)
One EF86 - high-mu signal-pentode, for the tone-ctrl and gain-stage.
One ECL82/86 driver and power pentode for our SE-AMP.
One output transformer, Z = 7k - 10k(if you want to build a stereo, make sure you use the same brand and model, the core and turn-ratio is critical, if you desire the same sound from each channel!)
One power-transformer(mains), 230 - 250V@100ma(or 160 ma for stereo) and 6V3@2-4A(4A for stereo).

I've based my design on this article, from a magazine, printed in...

Adding yet another variable (current vs. voltage driven) sure makes for a lot more measurements.

I survived figuring out Soundeasy's quirks once again with minimal bursts of cursing.

The following are the 3 driver's frequency response at varying levels of current drive vs. voltage.

For the woofer I'll clearly have to limit myself to more voltage drive given the peak at resonance, but for the mid tweet I can go current drive easily.

I'm not sure where I got the idea that current drive altered phase. The phase for the mid and tweet are identical for current vs. voltage and the woofer is close enough to measurement error.

Tony asked about the B1 active XO's. There's really not much to say. Any active filter that uses an opamp as a buffer (I.e. where output is directly tied to the '-' input) AND a cap blocks DC from the output to the feedback loop should be able to use a B1 like buffer. The circuits in sections 1, 2, 3 and 7 of SL's filter page all qualify, but the rest may be sketchy in my mind since the B1 can have some DC offset.

Attached is a rough drawing I scribbled last night for my own benefit, so it ain't pretty. An input buffer is something I'm still debating needing or not, but I'm leaving some room for it.

I'm going to let Soundeasy help me define the values, but the drivers are pretty well behaved in their desired bandwidth such that nearly textbook filters can be used.

I don't have enough JFETs of any one type for everything, so I'm going to have to mix types, probably LSK170s for the woofer and Toshi 2SK170s for the mid/tweet.

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