Please upload the schematic of your proposed PS, rather than linking a Google folder that might be deleted (That is diyAudio policy).
You probably should play around with Duncan’s PSUD2 power supply simulator. See:
PSUD2
A 5Z3 rectifier has a voltage drop of ~50V, so you will likely need some small capacitance at C8, rather than having pure choke input filter. A starting point would be ~5 uF film capacitor for C8; make sure it can handle the ripple current. Unless you have the specified capacitance for B+ on the Baby Huey PCBs, you will need more than 47uF capacitance at C6.
You probably should play around with Duncan’s PSUD2 power supply simulator. See:
PSUD2
A 5Z3 rectifier has a voltage drop of ~50V, so you will likely need some small capacitance at C8, rather than having pure choke input filter. A starting point would be ~5 uF film capacitor for C8; make sure it can handle the ripple current. Unless you have the specified capacitance for B+ on the Baby Huey PCBs, you will need more than 47uF capacitance at C6.
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Another tube I've just found that can be used here with 50% more power than any EL84:
https://frank.pocnet.net/sheets/168/7/7868.pdf
https://frank.pocnet.net/sheets/168/7/7868.pdf
the 6GM5 is a fatboy type nine pin.....https://www.tubesandmore.com/sites/default/files/associated_files/6gm5.pdf
Earlier in this thread Ian had made comments about the 7591, 7868, 6GM5 tube family that would be very good in the BH topology, due to their high gm and low drive requirements.
I recently purchased two quads of NOS 6GM5s for use in a BH. They have a very different pinout compared to EL84, so I plan to wire from the PCB to off-board sockets for the 6GM5s, rather than using adapters. If one is concerned about future tube supplies it is probably better to stick to 7591s.
I recently purchased two quads of NOS 6GM5s for use in a BH. They have a very different pinout compared to EL84, so I plan to wire from the PCB to off-board sockets for the 6GM5s, rather than using adapters. If one is concerned about future tube supplies it is probably better to stick to 7591s.
I am sorry but I have limited knowledge and I am now confused as would it not be better to use the 6V6/EL34 board for these tubes? I understand that even in that case, a socket adapter or off board socket would be required as the pinouts won't match. But still?
Seasons greetings,
Anwesh
Hi Anwesh,
Baby Hueys have been built using the output tubes you mentioned with the PCBs Marc and Prasi had done, as well as EL84 and others. Feel assured that it works fine with those tubes and there is no need to deviate.
But inquiring minds would like to know how 7591 type tubes would work in BH, and that was why this tube was brought up. The 7591 pin base is different than either EL84, and the 6V6, EL34 family tubes, for which the boards were designed, and would require off-board sockets or adapters. To my knowledge no one has done a Baby Huey with 7591s or its variants yet, but it is expected to work well.
Baby Hueys have been built using the output tubes you mentioned with the PCBs Marc and Prasi had done, as well as EL84 and others. Feel assured that it works fine with those tubes and there is no need to deviate.
But inquiring minds would like to know how 7591 type tubes would work in BH, and that was why this tube was brought up. The 7591 pin base is different than either EL84, and the 6V6, EL34 family tubes, for which the boards were designed, and would require off-board sockets or adapters. To my knowledge no one has done a Baby Huey with 7591s or its variants yet, but it is expected to work well.
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Transconductance is low, screen voltage is limited to 150V, why do you see it good for BH?
http://www.r-type.org/pdfs/6av5ga.pdf
http://www.r-type.org/pdfs/6av5ga.pdf
Hi Tony, I would keep the discussion about your suggestion on one thread only.
You used them in SE triode, here we are talking about PP UL. Totally different applications and curves. You can find my reply here: EL34 Baby Huey Amplifier
You used them in SE triode, here we are talking about PP UL. Totally different applications and curves. You can find my reply here: EL34 Baby Huey Amplifier
Hi everyone,
I have ordered the 1.6 EL84 boards from Prasi and the Mk.2 PSU board.
I have the BOM from GROUP BUY N°1, 2, 3 & 4 (December 2018) and my question is whether the BOM applies to one EL84 Channel board or both. If its only one then, I presume I order 2 of everything, if its for both then just what's on the BOM.
Can someone please advise?
Also I am a bit confused, does the EL84 1.6 Board from Prasi have the PSU circuit built into it? Is it worth using the PSU board? If I was to use the 2.0 psu board then which components do I leave of the 1.6 board?
Thanks for your help
Lee
I have ordered the 1.6 EL84 boards from Prasi and the Mk.2 PSU board.
I have the BOM from GROUP BUY N°1, 2, 3 & 4 (December 2018) and my question is whether the BOM applies to one EL84 Channel board or both. If its only one then, I presume I order 2 of everything, if its for both then just what's on the BOM.
Can someone please advise?
Also I am a bit confused, does the EL84 1.6 Board from Prasi have the PSU circuit built into it? Is it worth using the PSU board? If I was to use the 2.0 psu board then which components do I leave of the 1.6 board?
Thanks for your help
Lee
Post moved here from the EL34 thread.
Having just built both, I think it is only necessary to build the PSU board for the EL34 variant. You could have it for the EL84, but a lot of the functionality is duplicated, and you already have the benefit of a split power supply anyway.
Think hard about the orientation of tubes Vs heat sensitive components such as electrolytics. I built mine with only the tubes sockets on the face side, and all other components reversed. The goal is to move the bias lots of the board eventually, so maintenance is easy, and the top plate easy to make.
Think hard about the orientation of tubes Vs heat sensitive components such as electrolytics. I built mine with only the tubes sockets on the face side, and all other components reversed. The goal is to move the bias lots of the board eventually, so maintenance is easy, and the top plate easy to make.
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I've built it with all components on the tube side, except electrolytics and the heater switch that are on the opposite side. I'm planning to post here a drawing of the board, in order to make it easier to drill holes (screws, tubes and trimmers)
That would simplify the rebiasing and avoid six small holes on the top plate.
