Something tells me this is going to be a lot more work and a lot less effective than one would expect. Maybe my attempts at similar ideas have just been poorly executed, but I can come up with at least a few potential problems.
1- You need something to blow off excess steam pressure, otherwise your tubing is going to pop- I'm not sure a pressure cooker valve is going to be anywhere close to the right pressure.
2- That excess steam needs to go somewhere that is away from your high-voltage electronics.
3- That water will need to be replaced somehow.
4- Water has a very high specific heat, and even with a lot of power output it will still take an agonizing amount of time to build up sufficient pressure.
It is possible I am overthinking this- but I think that the stepper will be a lot easier. Even easier might be to use a small gear-reduction motor. Looks like small ones are a few bucks on ebay- all you'd have to do is wire up a limit switch. This would be electrically quieter than a stepper, and probably a lot easier. Use a threaded rod with a nut to raise and lower the amp. Decide how fast you want it to move up and down, then buy a motor that will get you that rate with a standard leadscrew, say 3/8-16 or 1/2-13. Obviously bigger screws with coarser threads will need a slower motor. If you get a 6V motor you could probably run it off a rectified tube heater winding.
As for speakers- I'm not the person to ask about full-range drivers (I've never been a huge fan of them), however I'd take a look at what Madisound has to offer- I've had nothing but good experiences with them.
Also, while the Zaph Audio website can be a tad bit outdated at this point (may driver recommendations are out of production), it is still a useful resource. I might take a look at his recommendation for the HiVi B3S. You can find his full range build http://www.zaphaudio.com/audio-speaker18.html.
Edit: That B3S is not going to be nearly efficient enough. Keep digging, Zaph's full range test should be a good resource.
Edit 2: The Dayton RS100 might be efficient enough if you use the Magnavox design and can live with a lower output level. The guys over on the full-range subforum might have a better suggestion, but this is the best I've come up with.
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It looks like another tube 6П14П is a complete analog of the 6BG5 where the cathode connected to g3:
The 6П14П (6p14p) is an EL84/6BQ5 equivalent. Unfortunately, the variant is not particularly good sounding. 
The 6П14П-EB (6p14p-ev), AKA EL84M, is a 7189 equivalent that sounds good, but the price is not especially nice. In general, the EB (ev) suffix on Soviet types is an indication of milspec superiority. Selection of the 6П15П-EB allows purchase of the milspec stuff at favorable cost. In addition, any decent EL84 or 7189 variant will plug right in, if/when a future "itch" occurs.
The 6П14П-EB (6p14p-ev), AKA EL84M, is a 7189 equivalent that sounds good, but the price is not especially nice. In general, the EB (ev) suffix on Soviet types is an indication of milspec superiority. Selection of the 6П15П-EB allows purchase of the milspec stuff at favorable cost. In addition, any decent EL84 or 7189 variant will plug right in, if/when a future "itch" occurs.Magnetics are the single biggest cost in a tube amp build. An expensive custom power trafo would be needed for the "oddball" voltage, along with a "normal" winding for the small signal tube.
Less than $21 for 4X very nice 6Π15Π-EB tubes that don't present a heater voltage issue helps contain costs in more than 1 way. BTW, the 6Π15Π-EB is Soviet NOS.
Less than $21 for 4X very nice 6Π15Π-EB tubes that don't present a heater voltage issue helps contain costs in more than 1 way. BTW, the 6Π15Π-EB is Soviet NOS.
I thought that adding a tube amp would make the player look more steampunk
Instead of steam how about a low pressure regulated air system with a small air air compressor and cylinder? With maybe a small damper shock. The robotics guys use a lot of this stuff. I've seen surplus blood pressure cuff compressors for cheap. Just a thought.
The 6П14П (6p14p) is an EL84/6BQ5 equivalent. Unfortunately, the variant is not particularly good sounding.
Eh, c'mon, the vanilla 6P14P aren't that bad
I've had good luck/results with them in conservative designs, but I tend to use them pentode connected in push pull, with higher open loop gain before feedback, and at a higher reflected load (10K vs. the usual 8K) for increased linearity. SE I can't really comment on, as I don't often go SE in general, other than by request on projects for others (and in that case, my usual choice in cases where power demand isn't really that high is triode connected 6V6) so I don't have much listening time on them in that use... The EV types are quite nice though.
I would add, if spending the money on EV types, that the 6P15P is a very nice tube indeed, and I would also mention another option, that would be the 6P1P- which is basically a nine-pin 6V6/6AQ5 equivalent. Also a very affordable option, although no pin-compatible alternatives, so buy a couple quads to last you. Triode-connected 6P43P-E is another option, and also cheap, with great linearity in triode mode.
I wouldn't take the 'steampunk' so literally That would be overkill IMHO. Even the idea with stepper motor causes some concerns. The main concern is that after multiple liftings the wires can break and taking into account very high voltages in tube amps that makes it pretty dangerous. Usually ribbon cables are used in such cases but I'm not sure that they can be used for tube amps because of high voltages.
I'm waiting for the final schematics from Eli Duttman. I think the photo taken from the hand drawn sketch would be enough. I could make nice schematics afterwards. After that I can start buying process. Though it looks like one of the main components - tubes were finalized: 12AX7 (1) 0A2 (1) 6Π15Π-EB (2) Please let me know if that's correct so that I could start buying/hunting process
That would be overkill IMHO. Even the idea with stepper motor causes some concerns. The main concern is that after multiple liftings the wires can break and taking into account very high voltages in tube amps that makes it pretty dangerous. Usually ribbon cables are used in such cases but I'm not sure that they can be used for tube amps because of high voltages.I'm waiting for the final schematics from Eli Duttman. I think the photo taken from the hand drawn sketch would be enough. I could make nice schematics afterwards. After that I can start buying process. Though it looks like one of the main components - tubes were finalized: 12AX7 (1) 0A2 (1) 6Π15Π-EB (2) Please let me know if that's correct so that I could start buying/hunting process
If you actually wanted to implement the stepper motor idea, I would look into the super flexible wire used for test leads with the silicone jacket- it's rated for higher voltages as a rule (easy to find in the 600V or even multiple Kilovolt range!) and is super flexible. With enough attention given to slack and strain relief I doubt it would be an issue long term. If doing so I would put all the transformers on the chassis being lifted, that way only the low-volt signal and speaker level stuff is being lead off-board, other than the AC line for the amplifier itself. This may even be a good place to use one of the higher voltage SMPS modules, that way you keep all the high voltage stuff on the amplifier subchassis completely.
Lingwendil, yes that could be the option to place tubes and output transformers on the same board and lift that board. That will mostly depend on the available space. The spec for the stepper motor which I referenced saying that it can lift 12.5kg which is roughly 25lbs - more than enough I think. Though lifting just tubes would be nicer, maybe mounting transformers on the other side of the board? We will see...
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Aside from the inevitable increases in parts prices since the web page was created in 2011, the big negative of the SE84 is its triode wired "finals" that yield "2" WPC. The OP stated 3-5 WPC in this thread's title.
Using the Edcor GXSE15-5K ($43.37), you can use the UL taps and minimal GNFB to get pretty good sounding amps. I've built both 6P1P and 6P41S amps that are quite pleasing.
EDCOR - GXSE15-8-5K
If you are really on a tight budget, drop down to the 10W version ($30.18) you will lose a tad of bass though:
EDCOR - GXSE10-5K
EDCOR - GXSE15-8-5K
If you are really on a tight budget, drop down to the 10W version ($30.18) you will lose a tad of bass though:
EDCOR - GXSE10-5K
Given shielding considerations, an aluminum plate, not a wood board, should be the platform that goes up & down. Arrange the tubes in a "Y", with the glowing gas discharge regulator towards the plate's front at the bottom of the "pillar", the 12AX7 at the "pillar"/"arm" junction, and "finals" at the ends of the "arms".
A possibility to limit the weight being moved is mounting the power transformers off the plate and use coiled, twisted, pairs of stranded wires to connect them to the on plate circuitry.
A problem with UL mode "finals" is the substantial CMiller the small signal circuitry has to drive. Fact, the 'X7 triode is a wimp whose drive capability is poor. Full pentode mode finals clearly avoid its limitations. The gas discharge screen grid regulator maximizes full pentode mode open loop linearity and also provides a cosmetic plus. Full pentode mode "finals" are not crap. Several manufacturers, including Fisher & Scott, achieved excellent results.
The 15 W. model allows for full bass extension, when the unit is connected to appropriate external speakers. If that option is permanently excluded, the 10 W. model will be OK. The I/P high pass cap. will change to 0.039 μF., which places the LF limit at 40.8 Hz. This part gets the job done.
For the speakers, I can heartily recommend these- FaitalPRO 3FE25 3" Professional Full-Range Woofer 8 Ohm
They are 91db/W efficient, and can take a pretty small sealed or vented box (.12~.13cu/Ft) with acceptable and clean bass response. Depending on how big your end chambers are they will sound either lovely or fantastic
They are 91db/W efficient, and can take a pretty small sealed or vented box (.12~.13cu/Ft) with acceptable and clean bass response. Depending on how big your end chambers are they will sound either lovely or fantastic
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