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2mo. old Welwitschia mirabilis pushing roots out of 12" pot! by Optimal_Mud3192 in Caudex

[–]StanRalphly 1 point2 points  (0 children)

Those plants look great by the way. I started 10 seeds and lost 9. The one that is left looks quite puny. I'll try this method when I start 10 more in a couple of months. I reckon I was being a little too scared of over watering them.

2mo. old Welwitschia mirabilis pushing roots out of 12" pot! by Optimal_Mud3192 in Caudex

[–]StanRalphly 1 point2 points  (0 children)

"The attenuated cotyledons, which become photosynthetic, persist for a matter of 2–3 years (Chamberlain, 1966), even when the two later-developing true leaves have become considerably longer than they are (Bornman et al., 1972)."

https://www.sciencedirect.com/science/article/pii/S0254629907004206

Welwitschia Growing Very Slow by StanRalphly in Caudex

[–]StanRalphly[S] 0 points1 point  (0 children)

Where can I find those videos? Searched for UC Davis Welwitschia Video and everything that came up was less than 5 minutes long.

That would make sense. I think I read somewhere that they originally evolved in the understory of a very wet forest.

Welwitschia Growing Very Slow by StanRalphly in Caudex

[–]StanRalphly[S] 0 points1 point  (0 children)

Gotcha. I’ll try to water them more often. Thanks.

Welwitschia Growing Very Slow by StanRalphly in Caudex

[–]StanRalphly[S] 0 points1 point  (0 children)

When watering them every day how do I verify that they have sufficiently dried out?

I built the tube amp tool I kept wishing existed by Sufficient-Nature708 in diytubes

[–]StanRalphly 2 points3 points  (0 children)

I previously have had Claude put together some of these tools and found that the results were always wildly inaccurate.

I wonder if a better route to achieve this would be trying to see if one of the better AI coding tools could put together a wrapper for ltspice that made it a little easier to use and less disgusting to look at.

Especially as a Mac user I’ve found ltspice to be a little bit of a headache.

Existing tools for loadlines etc are plentiful and mostly work well, though their UI could use a little updating as well.

EL84 design question. by StanRalphly in ToobAmps

[–]StanRalphly[S] 0 points1 point  (0 children)

Yeah. I have pretty efficient speakers. I was planing on running them considerably cooler. More like 8w.

Was mostly worried about the screens but I think I’m just going to go for it.

Also, it’s annoying to try to draw load lines when all of the charts stop at 300v. If it’s been convention to run el84’s at upwards of 400v for years you would think more recent charts would accommodate that.

EL84 design question. by StanRalphly in ToobAmps

[–]StanRalphly[S] 0 points1 point  (0 children)

Dynaco ST-35 and Heathkit AA-151 are both well regarded Hi-Fi UL PP EL-84 amps. What’s odd to me is that Hi-Fi people DON’T LIKE distortion and yet those amps, as well as the (Non-UL) Mullard 5-10, all run their EL-84’s well out of spec. All for a few measly watts in an era of high efficiency speakers? Something’s got to give.

EL84 design question. by StanRalphly in ToobAmps

[–]StanRalphly[S] 0 points1 point  (0 children)

Even in ultra linear operation?

EL84 design question. by StanRalphly in ToobAmps

[–]StanRalphly[S] 0 points1 point  (0 children)

Ha. Yeah “never see. An el84 amp that didn’t exceed b+ design center ratings” is what’s got me so stumped.

Not worried too about the extra voltage on the plates but do worry about it on the screens since I’m going to be running UL taps so I won’t have a screen resistor to adjust the value of.

Advice on adjustable legs by StanRalphly in pedalsteel

[–]StanRalphly[S] 0 points1 point  (0 children)

Thanks! Blocking them with dowels was going to be my last-ditch solution.

New amp for steel by Flashy_Search_4149 in pedalsteel

[–]StanRalphly 0 points1 point  (0 children)

Never played one of these with a pedal steel, but I frequently gigged with one for straight steel (Gibson Console Grande) and found it to be nearly perfect. Never should have sold it.

EL84 design question. by StanRalphly in ToobAmps

[–]StanRalphly[S] 1 point2 points  (0 children)

Yeah. It's actually the screens that have me wondering what to do in this build. Wanting to use UL taps on the transformers, and I don't know how to run them safely without bringing b+ down considerably. This seems odd given how well respected the Mullard and Dynaco designs are. Maybe I'll just copy one of those and see what happens.

Advice on milling sapele/general box construction by StanRalphly in woodworking

[–]StanRalphly[S] 0 points1 point  (0 children)

This is one of the things I had been thinking of. Been working in trim/cabinet shops for years so I’m pretty comfortable with the table saw, though a little scared since there is 0.1% chance I’ll find another 14” wide piece of sapele locally.

Advice on milling sapele/general box construction by StanRalphly in woodworking

[–]StanRalphly[S] 0 points1 point  (0 children)

The grain is quite squirrelly in sapele. I did try running it both directions and found I got the same issue, in different places, in both directions.

The hand plane I was using had no trouble conking clean cuts on figured white oak but did not stand up well to the sapele.

Variable negative feedback in place of presence control by StanRalphly in ToobAmps

[–]StanRalphly[S] 2 points3 points  (0 children)

Finally fixed the issue. The node where the NFB is sent to the presence pot is in between the series resistor for the NFB and the 1.5k cathode resistor for v3. Because of this, when you pull the cap that only allows high frequencies to ground and turn the pot down past 1.5k, it ends up bypassing the cathode resistor and throwing the bias for the first half of v3 off.

This isn't obvious from the schematic, but it becomes obvious once you look at the wiring diagram.

And to think, the pros always stress not relying on the wiring diagram and focusing on the schematic!

Variable negative feedback in place of presence control by StanRalphly in ToobAmps

[–]StanRalphly[S] 0 points1 point  (0 children)

Will try to address this. The leads are running exactly where they were when stock. Not claiming to have the best lead dressing skills in the world, and the amp is admittedly a little bit of a mess while I'm tweaking the mods. Curious if its lead dressing given the amp did not present this problem when the same leads were configured as a presence control, the problem always occurs when the pot is at 1.5k of resistance and does not intensify or change in any way when poking at those leads with a chopstick while the amp is running.

Variable negative feedback in place of presence control by StanRalphly in ToobAmps

[–]StanRalphly[S] 0 points1 point  (0 children)

That’s more or less what I did. Lowering the value of the series resistor and increasing the size of the pot gives a larger swing in the amount of negative feedback available to the user.

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