Bottlehead Kits > MonAmour

These 2.5V/2.5A filament 300Bs from EML might be of interest

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Deke609:
Just noticed that Jac of Emission Labs makes a 300B mesh tube with a 2.5V filament requiring 2.5A current - same as a regular 2A3. Perhaps they'd be drop-ins for the 2A3 in the MA, at one  or both of the MA's plate current settings. Perhaps PJ or PB could weigh in.

It'd be pretty sweet if they could work without having to make any changes. Of course, the JJ-2A3 40 is reported to be the same thing: a 300B with a 2A3 filament. I have both the EML 2A3 mesh and JJ-2A3 40 and used them in a Stereomour II. I like both, but I much prefer the 2A3 mesh - YMMV, IMHO, etc, etc. So, subject to what PJ or PJ says, for those inclined to tube roll these might be worth a try.

Fair warning: I've found that EML tubes take a long time to "burn in" -- 100+ hours in my experience. I have two pairs of EML's regular 300Bs, a pair of 45Bs and the 2A3 mesh - all took along time to really come into their own.

Here's a link: http://www.emissionlabs.com/datasheets/EML300B-25V.html   (no affiliation - I just like EML tubes)

cheers, Derek

Paul Birkeland:
They should work nicely in a MonAmour.

triode:
Derek

Emission Labs also has 2A3-S which is 2A3 with higher maximum dissipation.
Do you have a chance to compare between these 300B-25 vs 2A3-S ?

Which one would give more power in MonAmour?
Maybe Paul could estimate with limited data from Emission Labs site?

Thanks
 

Tom-s:
Both EML 2A3S and 300B2.5 (normal and Mesh) will work perfectly with MonAmour on high power setting.
The 300B2.5V should give a higher output power due to it's lower plate resistance (compared to 2A3).

Beware, the "normal" EML 2A3 Mesh (18W dissipation) is too stressed by the MonAmour at high power operating point, for Mesh tubes i'd go with the 300B 2.5V as you can use both settings on MonAmour.

Paul Joppa:
Technically, the EML 2A3-mesh is rated for 18 watts maximum, which is the MonAmour high-current operating point.

Admittedly, it would be prudent to stay below the maximum dissipation for such an expensive tube, and the filament voltage is not as tightly regulated as EML prefers, so they would probably not recommend it.

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