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drdna wrote:

I chose this for a sound most free from "graininess" which may change with PP2000. However, what is the rationale to change the impedence loading on the tube, from your perspective? As you know the Magnequest OPT has taps for 4,9, and 16 ohms. Your suggestions for an experiment after PP2000 is installed?

Yes, I do feel that with PP2000 the negative influence of “graininess" that you describe might be changed. It is not truly "graininess" but some kind of “diaphragms noise” that is most like the signs of bad electricity. With good electricity the "graininess" goes go up with increase of impedance but it in my view allow to increase of impedance higher with less negative feeling about the "graininess".

Generally with increase of impedance (more idle tube) you have less distortion, faster “sound”, l less harmonics, less power, and higher perception of transients among many other things. The lower impedance or the heavier load on the plate work in opposite way – slower transients, more power, more damping of diaphragm, less imitate sound, more masking effect over the driver imperfections. The right balance in my view is the loading state where the max transients are available but where the harmonics of the tone still maintain its acoustic signature. There is not rules in there and there is no way to measure it – it have to be done by ears as there are so many ingredients evolved into it, to name a few: type of tube, plate currant, type of the OPT, type of the transformer core, presence  and type of feedbacks, characteristics of the speakers drivers, type of the drivers, drivers integration methodology, listing distance, type of the speakers and so on and so on… As you underrated that rules of the game what you use multi-amping are very different as you have a chance to surgically load each narrow-bandwidth channel and shape the harmonics not only by loading but also buy the channel integration and creative crossovering.

So, what you begin to use PP2000 you might try to jump to lower tap of your Magnequest OPT. You will lose 3dB with each tap and will have “faster” sound. It is highly possible that you will not have the "graininess". What I think you would need to look is the state where the MF begin to be breaking apart and harmonic tail will not be any longer fill the gaps between  he transients. This parabola, with which tone roles to its pitch shell be a hill not a valley (unless you listen rock, pop, jazz crap). if you can grasp it right the way then let you girlfriend to hear the “flatness” of the tone and she will get it right the way. It might take for a while to properly load MF driver, I uselessly suggest going for faster sound and slowly step back, instated of going for heavier load and moving up in impedance.

BTW, the PP2000 does absolutely amassing thing – it laniaries harmonics across bandwidth, so you might find that it is fun to play with it.  

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