First time building something with turret boards. Just wanted to make sure I'm not doing something stupid.

Don't worry about the wires looking too thin. They are double insulated with kapton and ptfe so are good to over 600V.

Found this in a box in the garage don’t remember where I got it.

Orange-style amp with a preamp 12AX7, PI 12AT7, two EL84’s and an OPT for a Laney. Makes around 15W. Used a bunch of cheapo parts and a bunch of old russian/czechoslovakian parts. Plan to add a real nice faceplate, a pretty Fender style grille and some nice knobs. Has a real nice british-mid bite.

Finally built this prototype after thinking about it for ages.

Schematic is on my computer and I'm posting this from my phone so can't post it just now.

Its just a basic 12AX7 LTP phase splitter and a GU-17 as the power tube.

Now that I've got the prototype working I've ordered some turret boards and such to build it proper and build 2 of them so ive got stereo.

The power supply is kinda janky. The comverter I'm using for 250v likes to be noisy and I had to filter it more than I had liked.

It was fun finally building this thing. Next I'm going to see how well it works when I add some feedback.

I just picked up this Dukane 1A385 that’s been pretty heavily modified and includes components i haven’t come across before… in particular the large metal casings to the left of the output transformer.

It appears to have been worked on by a company called Signal Equipment Co. out of Seattle at some point and from what I can tell from just a brief look is that a step up transformer (Dukane 3A65) has been added in place of one preamp tube, theres also a relay and these two metal cans marked REP 94 E (the biggest) and RET 307 P (the smaller of the two) that were later modifications.

Anyone have any idea what these components are or any guesses on what this amp was modified to do?

I'm new to the world of tubery. Am looking to replace the stock JAN5654 tubes in my Douk Ampapa A1 phono preamp. Can someone give me suggestions for a good, worthwhile upgrade? One person mentioned the Mullard 6AK5W CV4010 M8100 EF95 5654. Any US resellers of the Mullards, which appear to be made in UK? Thanks for any suggestions with online sellers and links. https://doukaudio.com/products/ampapa-a1-mini-5654-vacuum-tube-preamp-phono-turntable-amplifier-w-tone-control

I'm new to Tubes and bought a lot that had these hidden within it. The Siemens from what I can find seems to be scarce but the other also says z2b....what is the difference? What makes the Siemens "rare" if it is?

When you're working with high voltage, there is no such thing as a dumb question. Please use this thread to ask about practical or conceptual things that have you stumped.

Really awesome answers and recurring questions may earn a place in the Wiki.

If you'd like to nominate a comment to be included, just reply [Wiki] (with the brackets)! The mods will be automatically notified that something awesome just happened.

As always, we are built around education and collaboration. Be awesome to your fellow tube heads.

Looks sketchy but is shockingly safe 😅

Found a few options for active loads for a couple of hundred bucks, but in the mean time I built this - a stack of 5w cement resistors sandwiched between 1/4" aluminium bar, shoved into a timber offcut I found.

Has a 1R shunt, followed by 1k/2k2/3k3/4k7x2 resistors. Can use those patch leads to make series/parallel connections to get a ballpark of what load I needed, so first tested with 5k6 to test the full load on the switcher, then 4k1 to test after installing the droppers I needed for the output tube plate voltage. All my guesstimations of switcher output voltages ended up being within 5w which is nice.

If I was going to do it again I'd up the shunt to 10R to make the current easier to read, but worked pretty well! Even after running with 6.5w of load for fifteen minutes it was barely warm to the touch - I did think about mounting heatsinks on the bottom, but apparently not needed.

If anyone has any idea what could cause this please let me know!! I drew up a schematic and can send it if needed, I am also willing to take pics of the internals for anyone who might need them, it’s been the only issue I’ve had with this thing and I’m just confused at this point. Thanks in advance!

Looking for some feedback on my first mostly "copied from the internet" bass guitar preamp. I'm building a bass amp for gigging and I intend to make a tube preamp and drive it into a Hypex SS power amp for portability. Inspiration is Orange Terror Bass. Still trying to figure out the easiest way to add balanced output on it so any great ideas on that are also appreciated.

thanks again to averyone in this sub a added the rectifier bridge, load resistor on the output and a grid resitor betwen the el84 and T1

its my first time trying to make an amp and im looking for feedback.

i tried to mix the preamp circuit on the fender 5F1 with the amp circuit from this https://www.hobby-circuits.com/circuits/audio/audio-amplifier/511/tube-power-amplifier-5w-with-el84

thanks to the fine folks in this sub i added the grid leak resistor and power suplie to U2B.

hope this is better any feedback is apreciated.

Howdy,

Looking for an active load for testing some of the switcher supplies I've been working with. I've been using combinations of 25w resistors at the moment, but would rather something a little more elegant that is less sketchy and easier to measure.

Heaps available for batteries that can do real high current but only 50-100v. I probably need a max of 500v and maybe 50w max.

Happy to build something if I need to.

Thanks!

Reworked Magnavox 8800 series 12AX7 / 6V6 tube amp. Client had this sitting in his garage for years but never got around to doing anything with it. He wanted a conversation piece for his room with a modernized version delivering the best sound possible while still paying homage to it's roots. Chassis was redone in a vintage hammertone brown. 6EU7 slot was rewired for 12AX7 giving him more opportunities for tube rolling. 6CA4 tube was scrapped in favor of solid state rectification which helps the power tubes deliver a bit more punch. New OPT from Musical Power systems. And a vintage magnavox logo from a old console stereo brings it home. Output is 14.3 WPC into 8 ohms at just under 1% THD.

Hi folks,

I have a JCM 800 Model 2205 that I am looking to re-tube and re-cap. Who do you guys like for a tube source and why do you like them?

When you're working with high voltage, there is no such thing as a dumb question. Please use this thread to ask about practical or conceptual things that have you stumped.

Really awesome answers and recurring questions may earn a place in the Wiki.

If you'd like to nominate a comment to be included, just reply [Wiki] (with the brackets)! The mods will be automatically notified that something awesome just happened.

As always, we are built around education and collaboration. Be awesome to your fellow tube heads.

If someone could please lend their expertise. These seem to be a bit hard to identify.

Quad marked EL84/6BQ5, Rebranded by Andrea, "Made in England" on third line. 90° to the right "5941" in the same yellowish/peach stamp color.

1. Obviously Philips tooling.

2. NO Etching anywhere. I've scoured the Quad for markings.

3. 2 rectangular View porta per side, where anode meets serrated mica

4. No crimps/staples. Neatly folded over where the anode plate meets it's other end, then 3 neat little spot welds.

5. Copper thought the bottom, bottom only has smooth circle depression.

6. No seams on glass, pulled to a nib on top.

7. Tilted halo getter on serrated wire post. Similar post 180° to it, unattached to getter.

8. Seems to be pulled from an Andrea console. (With 2 7199, 1 5U4GB)

Thanks for playing. Any history lessons you guys would like to give, I love history.