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Bigbottle MM/MC Hybrid Valve Phonostage PCB

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Bas Horneman

Bas Horneman

Ex-Moderator
Joined 2002
basaudio.wordpress.com/
Kevin and I received our boards. (Kevin's second board was shipped to me)

Thanks bigman!
 

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Bigman80

Bigman80

Member
Joined 2018
Over the last week or so, we have been having a play with the new Bigbottle Multifet boards.

The idea being that the pairing up of Jfets would offer a reduction in noise.

The first set of boards yielded a frustrating result. We could not get enough gain from them when using the BF861C fet. In fact, there was very little gain.

We then tried some discontinued BF862 that we had in stock, and this has provided the results we originally expected.

The noise floor is now lower by 3db, gain is a bit higher, which is good.

I have ordered 40 BF861B Jfets to try next, as we really want to use legitimately sourced Jfets, not only for their production quality but for reliability.

I have had multiple Chinese bought BF862 fail for no apparent reason, and that's a very little device to have to keep removing and replacing.

So, the next step this week will be to build 2 more Multifet boards and get them measured by Alan. IF all is well, I'll look at a group buy for them.

With the resistors being 0603 size, I am thinking the best way forward is to assmble them prior to delivery. But we'll cross that bridge when we come to it.



View attachment 847570 20200522_100639.jpg 20200522_111817.jpg
 
F

Flikoman

Member
Joined 2010
Bigman80 said:
Over the last week or so, we have been having a play with the new Bigbottle Multifet boards.

The idea being that the pairing up of Jfets would offer a reduction in noise.

The first set of boards yielded a frustrating result. We could not get enough gain from them when using the BF861C fet. In fact, there was very little gain.

We then tried some discontinued BF862 that we had in stock, and this has provided the results we originally expected.

The noise floor is now lower by 3db, gain is a bit higher, which is good.

I have ordered 40 BF861B Jfets to try next, as we really want to use legitimately sourced Jfets, not only for their production quality but for reliability.

I have had multiple Chinese bought BF862 fail for no apparent reason, and that's a very little device to have to keep removing and replacing.

So, the next step this week will be to build 2 more Multifet boards and get them measured by Alan. IF all is well, I'll look at a group buy for them.

With the resistors being 0603 size, I am thinking the best way forward is to assmble them prior to delivery. But we'll cross that bridge when we come to it.



View attachment 847570 View attachment 847571 View attachment 847572
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So, what's next? MC users who bought this board can't use it or?
 
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