Possible first ever DIY Questions

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Hi I recently ordered a frugel horn mk3 diy since im stuck home for months due to covid. I always wonder to diy but ive been putting it off but the speakers look fairly easy and I was considering this moreplay as a diy project. Im also new to tubes and had a few questions about the moreplay.

1. I got a friend who is helping build a Firstwatt F1J for the frugel horns. the power amp is a current source amp with no feedback would this preamp work well with it given that there is no feedback on the power amp?
2. How does this differ from the 300B pre amp sound vs this moreplay?
3. I like universal voltage option since i many move between places that have different voltages, what makes the 300b preamp not available in the 220V?
4. I think the 300B may be more microphonic and sensitive to vibrations is the moreplay less prone to this?

Thanks!!

[Karl5150]

Ivan,
I run FH3s off of the discontinued BH Seductor and am very pleased with the sound. I think how they work with a particular amp topography will be down to which driver you choose. I have Mark Audio Alpair 7.3s in the FH3s and think they sound better with with the Seductor than with the more premium Stereomour II, while the Planet 10 modded Fostex drivers come alive driven by the S II.
The BH crew can explain the why behind the sound, but having built numerous BH kits and a couple of other brand diy electronics, I can tell you that I have never been disappointed with a BH product.
Karl (BH Fanboy?) 

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Thanks for the input I got my kit from big wood studio planet 10 was out of stock and I had a hard time reaching them. I was able to order a pair of MAOP 7 drivers from mark audio but its on backorder from a reseller out in the UK.

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found this on firstwatt side hope someone more tech able will chime in to is if the moreplay is on paper a good match for this power amp

"There is another factor as well, which is that the F1J has a lower input impedance than the F1- approximately 30 Kohm balanced and 15 Kohm single-ended. The modifications that help achieve this bandwidth take advantage of lower impedances, so the F1J is recommended for use with preamps with ordinary to low output resistance – tube preamps without cathode followers will work but will not reap as much benefit at high frequencies."

[Doc B.]

"Will not reap as much benefit at high frequencies". What a silly way to say the high frequencies might be rolled off. A rule of thumb is to have an input impedance 5X as high as the output impedance of the source device. The Moreplay works with that rule, with 2K output impedance through the range of output you would likely be using with a First Watt style amp. That said I did have an experience many years ago where we had to modify the operating point and thus the output impedance of a different one of our preamps (Foreplay III) to work with the very low input impedance of some large Pass Labs amps. So I can't say for sure if this would be an issue or not. Short, low capacitance cables between the preamp and amp will be a good choice.

[Paul Joppa]

We haven't answered the questions about the 300B preamp yet. That preamp is undergoing a major revision, which is almost done and will be released shortly. It will have several variations, some of which should work well with low-input-impedance  power amps Stay tuned!