Vacuum tubes / valves

[Anonymous No.1138755]

Who else here is interested in obsolete tech?

I'm obsessed with these things, constantly build radios, amplifiers, and have a couple hundred weird tubes to play with.

Might have a go with some of the car audio shit that's only rated for 16V max plate voltage and cook them at 50V for fun. Just gotta finish my protoboard.

[Anonymous No.1138758]

Not to mention some are pretty neat to pull apart.

[Anonymous No.1138769]

>>1138755
Tube amp tech reporting

[Anonymous No.1138776]

>>1138769
What device is that?

I wish my Phillips tube radio were that clean and simple. Haven't done anything

[Anonymous No.1138777]

>>1138776
>Haven't done anything
Woops. Meant to say "Haven't done anything to it yet except replacing the filter capacitors".

[Anonymous No.1138784]

>>1138776
Guitar amp it looks like.
>>1138776
I feel you. I have an Eddystone SW receiver that needs work. It's never been touched and full of old Mullards, except for the 12AX7...which is a Brimar ffs.

[Anonymous No.1138795]

>>1138755
That is really cool

[Anonymous No.1138818]

>>1138776
It's an original marshall jtm50 plexi

[Anonymous No.1138820]

>>1138784
Mullards and Bri-mars you say?

[Anonymous No.1138821]

>>1138820
There are some Telefunkens and Amperex in there too

[Anonymous No.1138825]

>>1138820
Nice. I fell for the meme but slapped myself realizing there are more linear tubes than the 12AX7. I was disappointed since I could've pulled it and sold it on ebay.

[Anonymous No.1138827]

>>1138825
and my fucking photos are being dickered...

love this shit though, just been super lazy and unmotivated as of late but i have some ideas on a protoboard built to test tubes for audio suitability.

[Anonymous No.1138847]

>>1138825
Something like a 7308?

[Anonymous No.1138848]

>>1138755
I don't know the feeling.

[Anonymous No.1138849]

>>1138847
Also, another recent restoration project. Did a pair of them for a customer.

[Anonymous No.1138852]

>>1138847
Just discovered the 12BY7, considering a shitty little push pull class AB1 amp with fixed bias. Probably a pair of 6CG7 to drive and phase invert.

[Anonymous No.1138862]

>>1138852
Sounds like fun. I don't see those too often in the stuff I work on. Pic related

[Anonymous No.1138871]

>>1138862
If you don't mind me asking, do you repair amps full time or is it just a side thing/hobby?

[Anonymous No.1138872]

>>1138862
Right on, I have a Marshall Plexi carcass sitting on a bench. I keep saying "one day" but I keep starting new projects.

[Anonymous No.1138878]

>>1138849
>McIntosh Amp

As a young man I used to drool over those and dream of owning one.
I didn't even consider having two so I could have that new 'stereophonic' sound.

[Anonymous No.1138882]

Posting this because relevant:
https://simplifier.neocities.org/

it's not me. I don't think he posts here anymore.

[Anonymous No.1138888]

>>1138755
can you tell me whats this assembly is/do ?
look cool, i want it on my desk

[Anonymous No.1138892]

>>1138848
you post these in every thread mang.
nixies aren't vacuum tubes.

[Anonymous No.1138896]

>>1138892

But these are. Why have vacuum tubes if they don't do anything modern ICs can't accomplish?

[Anonymous No.1138897]

You're gonna love this https://www.reddit.com/r/diytubes/

[Anonymous No.1138912]

>>1138888
Just drives an old rectifier tube, nothing crazy.

I built a power supply using mercury arc rectifiers, they glow pretty bright but the uv light from them is bad for your eyes.

[Anonymous No.1138916]

Right now I'm working on a database of what I have and a "roll chart" for a prototype pp headphone amp I built. Some of these are insane tubes but limited in power.

[Anonymous No.1138917]

I've built 3 guitar amps and one stereo.

got the transformers to make a 50W EL34 PP.
gotten seriously sidetracked with modular synthesis, so I still haven't settled on a preamp or design for it.

[Anonymous No.1138941]

>>1138755
Obsolete!?! Fuck you!

Signed,

Jack Woo

[Anonymous No.1138943]

>>1138776
Looks nice, what model is it ?

[Anonymous No.1138950]

>>1138871
Yes, full time. Guitars too.

>>1138872
Do it!

>>1138878
gotta get binaural!

Pic is a fender tweed deluxe clone I built

[Anonymous No.1138956]

>>1138827
Top right - mercury rectifiers?

[Anonymous No.1138957]

Does anyone know of a source of cheap power transformers for tube amps?

[Anonymous No.1138975]

>>1138755
I love this kind of stuff. Currently trying to get this viewfinder CRT screen working because it just looks so cool. only getting static atm

[Anonymous No.1138982]

>>1138882
I post here, just anonymously :^)

[Anonymous No.1138988]

>>1138755
Make your own tubes: Part 1

https://www.youtube.com/watch?v=EzyXMEpq4qw

[Anonymous No.1138998]

>>1138957
Magnetic Components Inc./Classic Tone
Most bang for your buck, in my opinion. You could also just salvage parts from old equipment

[Anonymous No.1139077]

>>1138957
>cheap power transformers for tube amps
>power transformers
DIY !

Get a toroidal core and relevant copper and wind it by yourself.
Also depending on what high-voltage you need to fire anode rails, you may use an existing toroidal power transformer for HV, then add a dedicated filament winding

[Anonymous No.1139125]

>>1138982
How's the reliability / life expectancy of your tubes, now when you have used them for bit longer?

[Anonymous No.1139131]

>>1138896
What is a LCD

[Anonymous No.1139159]

>>1138957
For prototyping I get isolation transformers, a store here carries some that are 120-230V both sides, with multiple taps and are rated 65VA for about $25. Or Ebay.

230V rectified with 1N4007 will give roughly 175~325V depending on what tap I use which is plenty, Buy 2, wire them in series on the secondary, parallel on the primary and you get up to 650V for bigger stuff but I would use a heavier diode than 1N4007. Also gives you the option to use a tube instead like a 5Y3 or 6CA4. Or be whack and use mercury arc rectfifiers.

Shitty thing is you'll need separate transformers, one isolation, one for a heater supply, etc. for whatever else you'll need but it does allow for greater flexibility.

>>1138941
Relax man.

[Anonymous No.1139173]

>>1139159
What amp is that in your pic?

[Anonymous No.1139174]

>>1138896
>what are even order harmonics?

[Anonymous No.1139183]

>>1139173
heathkit a7

[Anonymous No.1139220]

>>1138943
>what model
B5X34A from ~1964

[Anonymous No.1139282]

>>1139125
They seem to last indefinitely if there aren't any leaks. In other words, if it works on day 3 it'll probably work on day 300. The audio amplifier from a year ago still works fine; I test it occasionally and it still puts out sound. Not really enough to be useful as a speaker, but the same volume as it did when I built it. I know a lot of folks, especially in the hackaday comments, were trying to come up with reasons why the tubes would fail, so it's been fun watching them be wrong.

Semi-related, but Brillite brought back their 5mm tubing (great for evacuation stems) so if you want to make tubes, now's the time to pick up some cheap glass.

http://brillite.com/itemdetail.php?sku=Clear%20Uncoated-18mm&p=Brillite+Fluorescent+Coated+Sign+Tubing&c=tubing&sc=Clear+Uncoated+Glass+Tubing

[Anonymous No.1139298]

>>1139131

>Liquid Crystal Display
>Vacuum Florescent Display

get gud

[Anonymous No.1139382]

>>1139298
do something new man, these old project pics are approaching meme territory.

[Anonymous No.1139384]

>>1138957
I buy them cheap from china.
bring the hate.

[Anonymous No.1139385]

>>1139384
or old butchered amps of coarse.

[Anonymous No.1139411]

>>1139384
You got any links? A lot of the ones that I have seen have expensive shipping.

[Anonymous No.1139415]

>>1139411
http://www.ebay.co.uk/sch/i.html?_from=R40&_sacat=0&_nkw=tube+amp+transformer&_sop=15

duuno what shipping is like to wherever you live, but i live in norway so i cant imagine it gets much worse.

the 15W PP OT lands at about 25 pounds, which isn't bad.
used it in my daisycutter and I love that amp.

stuff come and go so you gotta be vigilant for good deals, especially transformers saved from butchered amps.
they are usually low wattage though.

[Anonymous No.1139783]

>>1139415
thanks. I checked ebay a while ago, but I haven't seen much. I'll make sure to check every once in a while to see if there is anything good.

[Anonymous No.1140242]

>>1138755

Tubes are A+ comfy.

[Anonymous No.1140293]

>>1138896
>>1139298
VFDs are sweet, I just bought 12 IV-22s and 6 IV-11s for 30$

I was thinking about using an AVR, a boost converter and some transistor arrays to drive them. What are you using?

Also, where did you get these? >>1138848

[Anonymous No.1140777]

>>1140293
I have some IV-11 and a max[something] driver but i havent gotten around to doing something with it yet

[Anonymous No.1140781]

>>1138755
>obsolete tech

I still deal with them at work sometimes but its the larger variety.

Have not died yet.

>840 watts
>Filament

[Anonymous No.1140797]

I had a question about low pressure sodium lamps.. if the MFR specifies an operating voltage, will constantly applying that voltage eventually ignite it? Or do I absolutely have to apply the high voltage to kick-start it?

[Anonymous No.1140800]

>>1140781
What the hell does that monster drive? A radio tower transmitter?

[Anonymous No.1140812]

>>1140293

Using an Atmel 328 hooked up to a HV5812 driver. It acts as a 20 bit shift register, so you have 20 HV out pins to work with. So theoretically you can drive up to 12 IV-22s with it if you multiplex.

[Anonymous No.1140941]

>>1138769


Can I send you a Peavy Power Amp to fix?

[Anonymous No.1141012]

>>1138755
Jcm 900 checking in. It's a cunt to bais

[Anonymous No.1141029]

>>1140800
Yeah. High-power transmitters are one of the few applications where tubes are still worth considering or even the only practical option.

[Anonymous No.1141076]

>>1139159
>230V rectified with 1N4007 will give roughly 175~325V
How ? I've never heard about 1N4007 diodes being able to create such an amount of extra power from a rectified sine !

[Anonymous No.1141107]

>>1140797
Its just a matter of adding a cap in there, shoyldt be too hard

[Anonymous No.1141115]

>>1141076
if you rectify AC into DC your should multiply the AC voltage with the root of two (1.41). 230*1.41 = ~ 325 volt. from there he uses some caps and resistors (or maybe a choke) to get different voltages and lower ripples

[Anonymous No.1141129]

>>1141076
I should've started that sentence with 120-230V to clarify. The transformers are tapped 0-120-208-230, hence the range, also:
>>1141115
Exactly. Also depending on the power of the transformer, and other components used, it can sag especially with heavy RC filtering. Good chokes are expensive but are more efficient and will prevent that.

[Anonymous No.1141142]

>>1141115
Bullshit.
Also stop spreading this meme : there are kids and rednecks watching threads on /diy/

>picrelated.jpg : even MSpaint says you're wrong

[Anonymous No.1141154]

>>1141142
Not power, but voltage. Do you not know the difference?

[Anonymous No.1141155]

>>1141142
Why? It's a foolproof way to estimate voltages under no load conditions.

A brainless equation in a second can inform me that for 230VAC rectified, I will need at least a 350V cap, 400V to be safe.

[Anonymous No.1141195]

>>1141142
just in case you are simply stupid and not trolling: Vrms = Vpeak / 1.41

since Vrms doesn't exist after rectification you will get Vpeak, hence multiply your Vrms with 1.41 to get your actual DC voltage.

[Anonymous No.1141238]

>>1141142
A sine wave with a peak of about ~170V is specified by what the equivalent DC value could deliver. So it would be called ~120VAC (RMS)
A square wave generally has a different purpose than delivering power, so it's spesified by it's peak value. a 5V square wave has a high value of 5V

[Anonymous No.1141888]

>>1141238
>A sine wave with a peak of about ~170V is specified by what the equivalent DC value could deliver. So it would be called ~120VAC (RMS)
That was the information I lacked.

My bad : I usually work with small radio signals, hence I'm referring to them with their "amplitude/freq/phase" parameters... Not Vrms, not Vpeak.
And I've never plugged an oscilloscope to a mains outlet "just to check how big the sine wave was", because I don't have a suitable isolation transformer and because it felt retarded to me to "double-check" such a "boring signal".

I learnt something today... Thank you !

But why the fuck does power company refers mains voltage by their mean value instead of their amplitude ?
What's the (retarded ?) reason behind this ?

[Anonymous No.1141903]

>>1141888
>But why the fuck does power company refers mains voltage by their mean value instead of their amplitude ?

Not sure how exactly to put it into words but the RMS is the 'actual/useful' voltage as compared to DC,
If peak was used then Ohm's law would be fucked.

[Anonymous No.1141998]

Anybody got experience with Chinese tube kits? I've been looking at a few shortwave/AM regenerative receiver kits on Aliexpress and eBay.

[Anonymous No.1142018]

>>1141888
>But why the fuck does power company refers mains voltage by their mean value instead of their amplitude ?
It's not the mean value. The root mean square value is kind of a "dc equivalent" value so that a 120V heating element produces the same amount of heat when fed from a 120V DC source or from a 120Vrms (170V amplitude) AC source. Things get different when the load isn't strictly resistive, but usually people try to make AC powered equipment to look reasonably resistive.
It's a very convenient way of express the voltage (or current), as you can ignore the waveform in many cases and, for example, use the same 10A rated wire in both DC and AC applications as 10A wire.

[Anonymous No.1142122]

>>1141998
nothing special but if you're getting into it, it's a good place to start

[Anonymous No.1142239]

op here, testing some tubes, whole crapload of 6080, sections inside are laughably mismatched most of the time.

[Anonymous No.1142244]

EL34 testing

>ton of unknown russia tubes
>had what I thought were NOS Philips tubes, still in fucking boxes and look perfect
>test them one was 10mA the other 4mA
>spec is 70mA, they're fucked
>decide to screw with these because at least the other 13 tubes are good, some excellent

>turn plate voltage to 400V
>grid bias at -2V
>cathode current doesn't move, then starts to climb
>MFW it's red plating after sitting there for 5 min seemingly only doing 40mA or w/e, now at 80.
>must be good, swap for other shitstain
>try the same bullshit, does fuck all
>check other tube, back to 10mA when cold
>MFW I thought these were new, coulda sold them but they're total trash

More shit:

>decide to fuck around with shitty EL34s
>Ruby china tube tests ok 50mA but tends to make amps do weird shit
>decide to crank plate voltage up..300...350...4..
>MFW my DMM starts to scream and it sounds human
>hit the standby, wonder wtf
>meter's not hooked up, maybe someone outside
>start thinking it's paranormal shit because too much /x/
>try again...200...300...375..
>SCREEEEECCHHH
>hit standby, this time notice the current was pegged at 125mA
>ok then
>turn power on, keep meter away
>turn up voltage...nothing, 400v and 90mA
>bring meter close to tube
>SCREEEECH
>mfw it sounds like a woman screaming, it's freaky
>the DMM isn't connected...how the fuck
>pull meter away and it stops, but tube was bright purple / blue, current again pegged
>huh
>try it again, realize the "scream" in the meter is the piezo electric beeper
>it's affected by plate voltage to a point, but turning the voltage down to 0 with the meter >3cm from the tube has no effect
>realize it's oscillating, but when it does, it's holding the output of the supply at 400V
>fuck with it a bit, it's neat, probably a stability issue in the power supply, fascinated by the fact it's somehow drawing electrons to be able to do that
>then again...only tube that's able to do it
>made in china
>start to wonder about radiation and xrays

[Anonymous No.1142267]

>>1142239
>whole crapload of 6080
Well good point with the 6080 is its *low* Ra matching impedance, circa 300 ohms if I member well.

>tl,dr;
if you don't mind parallellizing a (metric) shitload of tube, heat/Joule losses, manual/fixed biasing, and fancy preamping because 6080 have low µ and low S, you have solid OTL masterace here.

>picrelated.jpg
Google for "Peterson-Sinclair" output-stages : I'm pretty sure to have seen some 6*6080 // amp somewhere in the Interwebz

[Anonymous No.1142268]

Does a jcm900 still sound like a tube amp even though it has solid state distortion?

[Anonymous No.1142276]

>>1142267
I've seen a lot about OTL, but not interested. 6080 is not very linear sadly...it's kind of a bastard tube, likes low voltages and high currents better.

6336A is a better choice but expensive...actually curves look quite linear in comparison.

That said, 6080 is good for headphone amps, however the 6336A kills it...but 30W~ just to run a heater to power headphones is a little silly.

[Anonymous No.1142371]

>>1138769

[Anonymous No.1142577]

Does anyone have any recommendations for tube related literature and media to learn more about this stuff (mainly beginner material to explain the basics)?

[Anonymous No.1142604]

>>1142577
Well I've learnt a lot of stuff from my grandpa's book. They are in spic because back then he lived in Spain.
Some stuff may seem old or outdated, but for tube and old-school elctronics/electricity basics they are solid material.

Also contains a lot of (rare ?) abacus for inductors, capacitors, transformers IIRC, and a lot of other stuff

>And Google delivered me all the pdf
http://www.acrayara.com.ar/biblioteca/public/Electr%C3%B3nica/48%20Lecciones%20de%20Radio%20-%20Tomo%201%20-%20Jos%C3%A9%20Susmanscky.pdf
http://www.acrayara.com.ar/biblioteca/public/Electr%C3%B3nica/48%20Lecciones%20de%20Radio%20-%20Tomo%202%20-%20Jos%C3%A9%20Susmanscky.pdf
http://www.acrayara.com.ar/biblioteca/public/Electr%C3%B3nica/48%20Lecciones%20de%20Radio%20-%20Tomo%203%20-%20Jos%C3%A9%20Susmanscky.pdf
http://www.acrayara.com.ar/biblioteca/public/Electr%C3%B3nica/48%20Lecciones%20de%20Radio%20-%20Tomo%204%20-%20Jos%C3%A9%20Susmanscky.pdf

I don't know if a translation exist in another langage, but as I managed understanding most of them as a French speaking guy, you're very likely to do so (until you're untermensch)

[Anonymous No.1142707]

>>1141888
>But why the fuck does power company refers mains voltage by their mean value instead of their amplitude ?
Simplicity in calculating power, that you pay for, with ohms and watts laws... probably.

[Anonymous No.1143050]

Been screwing with more tubes, figured out a way to plot characteristic curves which is very time consuming...adjust voltages, record data, repeat x number of times for each grid bias. I need a curve tracer, it's very interesting information.

Fried a 4BQ7, melted a hole in the plate because I wanted to see how much effort it would take to get the internal parts to off gas. The answer was not much and a crazy light show. When it finally gave out, it took out both cathode resistors and a huge flash, surprised the envelope didn't crack.

[Anonymous No.1143051]

>>1143050
4BQ7 that was a bit of fun, gonna try this with some shittier tubes.

[Anonymous No.1143800]

>>1138848
(((steins))) gate

[Anonymous No.1144070]

>>1141142
idiot

>>1141195
this guy gets it.

[Anonymous No.1144197]

>>1144070
read the whole thread faggot

[Anonymous No.1144262]

I have an old tube radio (American five or something?) that doesn't work.

Might drop into this thread in a couple weeks for some help getting her going again...

[Anonymous No.1144654]

>>1142239
i want to make sweet sweet love to those tubes

[Anonymous No.1144655]

>>1142276
can confirm, am building 6080 based headphone amp

[Anonymous No.1144780]

>>1144262
>replace the caps, do all the electrolytics. you may find all the paper caps are bad too. mica and ceramic are usually pretty reliable.
>measure resistors, most should be ok but they're getting old enough the values rise because the carbon has changed from the effects of humidity. cheap even for 1% parts, it's better just to replace them while you're at it
>if you're lucky, you won't need to realign the radio
>replace line cord and ground the chassis

tubes are usually pretty reliable, unless the getter inside is white they should be ok but don't be afraid of switching them out for new ones.

[Anonymous No.1144831]

>>1144655
single ended or push pull?

[Anonymous No.1144907]

>>1144780
Nice one thanks fella. I already plugged it in to see if it worked and all the tubes got to glowing so I assume they're OK. It hasn't had a particularly hard life so should be fine

Since I plugged it in, I assume the caps are charged up - how do I avoid a shock? Just touch a screwdriver across the two capacitor contacts to discharge it?

[Anonymous No.1145063]

>>1144907
The best way to discharge a cap would be to give some resistance to the thing that you're discharging, like a pair of alligator clips attached to a resistor or light bulb.

Also, if you plan on working on more tube gear like radios and amps, you should make yourself a current limiter so you know if something is wrong with the device.

https://www.youtube.com/watch?v=wRFRwOnLsZI

[Anonymous No.1145367]

>>1144907
you can't change the effects of time aging components. they do go bad and it's not a matter of if but when. all american fives especially so because they were built to a price and made with cheaper components.

plugging in an old radio or tube amp that's been sitting dormant is risky.

[Anonymous No.1146424]

>>1145063
Ok cool I can do that. I'll have to root out a multimeter and figure out how to tell if there's any charge left. But I'm sure I'll be fine if I take my time - this ain't gonna be a rush job.

As for the current limiter - will do. I'm gonna have a lot of time on my hands so may as well do as many projects as I can.

>>1145367
Yeah this is old so you're right I'll probably have issues. But I think the tubes survived: I'll figure that out soon enough. I may have made a mistake plugging it in - but if I hadn't I wouldn't know it's broken! Sure I love a projecy

[Anonymous No.1146972]

finished my stereo today.

[Anonymous No.1146973]

>>1146972

[Anonymous No.1147005]

>>1138755
check the capacitors first. you'll blow the power regulation caps if you dont.

[Anonymous No.1147009]

>>1138862
serious question. how does one blow an amp? are they operated by idiots? are they of extremely poor construction? none of my amps has ever blown but maybe that's because ive only ever built them within the specified tolerances of the parts i use.

[Anonymous No.1147011]

>>1147009
pushed too hard and spilled beer on it are the only stories i've heard.

only issue i've ever had is one pentode's heater breaking.
>>1146972
on this amp incidentally.
its seen a lot of use before i put it in a chassis, so no real surprise there.

[Anonymous No.1147013]

>>1143800
Kek

[Anonymous No.1147021]

>>1139384
this is something the chinese excell at. stamped metal parts, wound wire and a bunch of goop to coat it all.

>>1139385
generally not worth it. something with a decent shielded transformer tends to get repaired. the rest mostly use those shitty yellow square ferrite core pieces of shit.

>>1140797
please learn more about our good friend tesla. gas bulbs dont have a filament. they need the starter first, which creates the arc, which acts like a filament by making this thin little stream of charged gas with a lower resistance than the cold gas, allowing enough current to flow.

>>1141155
>he filters it into DC before the transformer steps it down
>he sees no problem with this
hmmm

[Anonymous No.1147023]

>>1147011
>pushed too hard
is this a meme?
why dont manufacturers use modern power supplies? I repair DSLRs below the board level. people drop their cameras IN THE OCEAN. I just clean them out, replace a fuse here or there, clean off the corroded shit and salt, lubricate the electromechanical parts and they work perfectly again. the power boards are some amazing shit though. in terms of how protected everything is. so much redundancy.

[Anonymous No.1147024]

>>1144197
you do know the difference between rms and peak voltage right?

you are comparing
rms of a square to the rms of a sinewave.

the problem is:
rms square = Vpeak
while
rms sine = Vpeak/1.41

>>1141142
if you look at the chart you made, you see that the peak voltage is the same, thus the rms of the sine is lower.

get a formula book.

[Anonymous No.1147026]

>>1147023
do DSLR's run on 300 or more volts?

apples to oranges here mate.

on the pushed too hard bit.
som half deaf guitarist with a boost and 3 fuzzes give and amp a hard time if he wants to.

that said: generally, tube amps are quite robust.

[Anonymous No.1147038]

>>1147026
the flashes circuit does. repaired one the other day, the only problem with it was some dried coca cola in a ribbon socket shorting a 600v supply line to ground

that's a matter of current limiting circuitry and optoisolation. never allow a direct layer 1 to layer 1 interface between random devices. the guitarist can choose to overload his amp but it will cut out before the thermal limits are reached. its the sort of idiot proofing you need in a design for use by people who dont understand why its not loud enough so they just kill it by raising the gain. that said, I cant stand live music because all the audio "engineers" are deaf and the retards throw the gain so high that it's almost static with the way they're lowering the noise floor delta.

[Anonymous No.1147043]

>>1146972
>>1146973
op here, pretty cool, how does it sound? what's the output tubes?

[Anonymous No.1147049]

>>1147043
thanks.
6005 pentodes
its from a kit i built like 5 years ago, before i took the dive into scratchbuilding tubeamps for guitar.

16w per channel.
not huge, but i've only gotten drunk enough to listen to in on full once in those 5 years.

just never got around to building a decent chassis before now.

[Anonymous No.1147052]

>>1147049
>pentodes
oops, i mean tetrode

[Anonymous No.1147057]

>>1147021
>he filters it into DC before the transformer steps it down

Nope, I have isolation transformers that will do 100~230VAC. In my case, being in Canada, I have to step the voltage UP before rectifying.
Hence 120VAC stepped up to 230VAC, then 230 * 1.414 = 325.22VDC.

Unfortunately that's not enough though for some amps so I actually have to buy the proper transformer. Sucks cause isolation transformers are so cheap.

Unless you meant something else?

[Anonymous No.1147063]

>>1147023
>why dont manufacturers use modern power supplies
what switchmode psu's and thermistors and shit?

imho its not needed

also tubeamps are sold with a degree of 'oldstyle'
purists dont want silicon on their amps. they call it 'sand' in disgust.
that's why some still use tube rectifiers.

i use diodes, i dont care.
I'd like to try a rectifier tube once to test, but the added heater current and low current capacity (in rush can kill them right?) is a bit of an annoyance for virtually no benefit.

[Anonymous No.1147066]

>>1147057
do you get separate transformers for the heater?

as posted earlier I buy transformers from china, but i have some beefy isolation transformers around and I'm on 220v so maybe i should try those some time.
I seem to recall the are rated for 1A/ 220VA.

[Anonymous No.1147084]

>>1147066
yep, gives you choice...get a 6-0-6v secondary and you get a bit of choice if you need it.

[Anonymous No.1147404]

now that my stereo is done, I think i need to build a proper tube RIAA.
I have one from a kit based on sub miniture tubes, but it starts oscillating sometimes.

any circuits to recommend?

I was looking at marantz 7c, which is supposedly great.
I got some 6n2p tubes I'd like to use and they substitute for 12ax7's quite well as far as i know.
works well from what I've tried in guitar amps atleast.

[Anonymous No.1147409]

>>1146972
more details on the stereo.

when testing during rebuilding, i fried my previous control board.
i connected 12 to the H bridge driving the motorized potentiometer and friend the receiver, mcu and other things.

I decided i would rebuild it with Cmos logic instead of a µC.
getting the channel selection to work was a bit of a challenge. as wanted a rotary switch on the chassis while being able to cycle channels with the RF remote.

I did this with 2 dual 4way muxes and a 2 bit binary counter. look in ohm for a drawing.

there is also a female IEC connecor on the back for powering a RIAA stage.
this is only powered when in channel 1.

the power relay is controlled by a JK-toggle. so i can turn it on/off with the remote and the switch in the front.

the nixie is pulled down with the ULN2003 driver for the relays, with diodes to prevent the nixies higher voltage to leak through the relays and light up unwanted.
the nixie's step up converter and the bulbs for the VU-meter is in driven by the same ULN stage as the power relay, so they dont light while amp is powered down.

Cmos can be a little unpredictable, so when first attach power to the controller board, on/off state and channel state is quite random^^
obviously the board is mean to be powered continuously.

[Anonymous No.1147411]

>>1147409
now i use an RF controller with relays on board.
making driving the motorized potentiometer trivial.

also gives a satisfying click for every function on the remote.

[Anonymous No.1147449]

>>1144831
Single ended, pushpull pair of 6080's would be obscenely powerful (and power hungry)

[Anonymous No.1147462]

>>1138755
I still want to design my own nixie clock

[Anonymous No.1147790]

>>1147462
buy some cheap form ukraine, get an arduino and go to ohm.

i use one for channel indication here.
>>1146972

[Anonymous No.1147808]

I am currently attempting to design a guitar effect pedal based around a 6AV6 tube and 2N1303 Ge's...mostly because I want to see what I can get out of it, and because I don't want to use any 12A*7 tube.

[Anonymous No.1147829]

>>1147808
cool.
are you thinking low voltage like the valvecaster or something higher?
I assume low as diode clipping would kill almost all of your signal at higher voltage unless you use a lot of them in series.


I built a valvecaster many years ago, it really livened up my boring marshal.
haven't really used it since i built my daisycutter.

[Anonymous No.1147854]

>>1147829
I was thinking it would be possible to use the triode for gain, and the diodes for clipping. Not sure how this is going to work yet with a common cathode though. I was going to eventually try and mix in some Si fuzz, Ge fuzz, LED fuzz, and valve fuzz circuits.

[Anonymous No.1147903]

>>1147854
haven't used common cathode before, but i think fully bypassing it with a big 'ol cap is good to prevent unwanted feedback from the last stage to the first.
this could lead to compression... i think..

or you could use diode or led bias for a steady voltage drop that doesn't (to any practical degree) with the current of the stage.

[Anonymous No.1147928]

>>1141195
>Vrms doesn't exist after rectification
calculating/measuring the RMS value of a DC signal yields the same result, dipshit
lrn2math

[Anonymous No.1147989]

>>1142244
What tester were you using? Also, -2V at the grid is absurdly underbiased. Any EL34 would redplate.

>>1142268
Nah, they're shit.

>>1142371
What is this? I wouldn't trust those brown paper covered electrolytics.

[Anonymous No.1147993]

>>1142577
Pic related for guitar amp stuff. The Dan Torres book is hands down the best for beginners.

[Anonymous No.1148008]

>>1144907
I used a clip, probe, and 20k 2W resistor to make mine.

>>1145063
>current limiter
I've never really found that necessary. I like to remove the mains fuse, put an appropriate breaker across the fuse holder, then bring up voltage on my variac which has an ammeter. If it draws current, turn it off and figure it out.

>>1145367
PREACH

>>1147009
The most typical 'blown amps' I see have had a power tube blow, either from age or omproper bias. It's common for them to fry the screen grid resistor when they go. If you're really unlucky they take the power tranny out too.

>>1147023
It's not typically the supply unless youre running old ass filter caps. It's the tubes typically. Underbiasing or total loss of bias.

>>1147829
>valvecaster
That was my first diy pedal! Very fun project and surprisingly good sounding.

[Anonymous No.1148013]

>>1148008
>take out the power tranny
Oops, meant the output tranny

[Anonymous No.1148032]

>>1142577
merlin blencowes books.
his site is also a great resource
google valve wizard.

[Anonymous No.1148035]

>>1148008
>That was my first diy pedal!
me too bro.

[Anonymous No.1148054]

I may have hit the jackpot, my university is going to throw out all their tube based electronics experiments. I will get it all for free in a week or two

[Anonymous No.1148060]

>>1148054
What type of stuff? Sounds like a good score

[Anonymous No.1148063]

>>1148054
>I have hit the jackpot, my university is going to throw out all their tube based electronics experiments. I will get it all for free in a week or two
ftfy

[Anonymous No.1148075]

>>1148054
daum, im jelly

[Anonymous No.1148204]

>>1148060
No idea what it is exactly, the guy who organises everything for the student practicals stashed it away three decades ago when that stuff really was out of fashion so he doesn't remember what's in the storage. But it could be anything from a box of abused tubes and sockets to cool experiments, powersupplies, tube testers and God knows what. I hope for an awesome stash but anything is cool and it would be so sad if it all ended up in the dumpster.

I'll let you guys know

[Anonymous No.1148214]

>>1148204
>>1148204
please do. post pics

[Anonymous No.1148291]

>>1148204
>stashed it away three decades ago
they kept teaching tubestuff til the 80s?

[Anonymous No.1148447]

>>1148291
I have a community college textbook written in 1978 and it spends around 1/6 of its pages on tubes.
It justifies that by saying that while (normal) tubes are totally outdated for anything new, there's still plenty of tube equipment around.

[Anonymous No.1148454]

>>1148291
The subject was still worth some time in those days.

>>1148447
exactly

[Anonymous No.1148519]

Bumping with '56 fender pro I rebuilt recently

[Anonymous No.1148525]

>>1148519
sweet.
what did you have to fix/what was the fault?

[Anonymous No.1148528]

>>1148525
Someone had added an extra preamp tube for an effects loop. It was a mess. I pulled that shit out, replaced some leaky/out of spec coupling caps, and did all the electrolytics.

[Anonymous No.1148531]

>>1140293
I finally got my VFDs in perfect conditions.

[Anonymous No.1148534]

>>1148531

[Anonymous No.1148536]

>>1148531
vfd's are cool and all, but this belongs in /ohm.

[Anonymous No.1148549]

do you guys prototype or just go straight to build?

if so, how do you prototype`?

pic is a prototype of a recent amp amp.
havent decided if i wanna build it for real or try something else yet.
its been collecting dust for a few moths as i work on other stuff.

I built the powersupply to spec as i dont have a Variable HV supply.
I slowly ramp up the first times with a variac though.

any tips on tools or helpful equipment i can make myself?
like a variable HV psu.

[Anonymous No.1148610]

>>1148531
i have a bunch of IV-11 which i wanted to use for a clock. never got to it :(

[Anonymous No.1148811]

for a HV supply, could i use a triac to control the secondary of a transformer before rectification and smoothing?

I'd probably need some fast bipoars as well as a big 'ol back of electrolytics. but it seems doable in my head.

I only have one variac and I'd like to keep it free.
besides, a variac AND the big transformer would make it really heavy.

[Anonymous No.1148820]

>>1148531

Get an HV5812P to control it. 20 bit shift register so you can theoretically multiplex 12 of these off one chip.

Although, I don't think it's bright enough multiplexed.

[Anonymous No.1148826]

>>1148820
how do you switch the high side personally?.

make a clock with this smaller dirt cheap 8x7 seg tube a while ago.
ended up with 2x 74595 driving 2x uln2803.
the high side pulled up with resistor arrays, then shorted to ground b the ulns.

bright and efficient non the less. though it was funny how it pulled more current NOT lighting a digit.

[Anonymous No.1148828]

>>1148826
I also made this incandescent 7seg clock.
i like the colour a lot more.
i put more effort into this, so i can actually set time without having to reprogram it.
though the ds3231 is so accurate its hardly a problem at all.

[Anonymous No.1148830]

>>1148828
forgot the pic and now i cant find it.

its beside the amp here. >>1146972

[Anonymous No.1148831]

>>1148826

What do you mean switch the high side? The HV5812P does all the work for you. High voltage (for me 24V in) with 20 HV out pins and 5V power with 5V logic.

[Anonymous No.1148840]

>>1148831
ah, k. haven't used driver chips for vfd's.
i just cobble together my own.

[Anonymous No.1148869]

>>1148840

I find making discrete drivers a pain in the ass. Trust me, the driver chip is worth the $2.

[Anonymous No.1148882]

>>1148869
different strokes.
finding my own solutions to problems is part of the fun sometimes.

[Anonymous No.1149065]

>>1148820
I have a box of MAX something laying around but i suck at programming

[Anonymous No.1149252]

>>1148536
i really don't want to see all the dumb questions / stupid microcontroller shit.

plus generals are stupid imo

i want to build a push pull 6jk5 class ab1 amp with 3500V on the plates but...

a) where the fuck am i gonna find output transformers rated for that
b) ditto on capacitors, especially for power supply stuff, probably be relying on chokes for most of the filtering
c) it'll be huge and a hefty sob with maybe 50WPC
d) 3500V is absurd for an audio amp but my head is screaming increased electron velocity which more than likely won't make any difference

[Anonymous No.1149253]

>>1148811
just build a regulated supply with 6080 or something similar.

what's your voltage / current requirements? you might be able to get away with this and a multitapped transformer: http://www.angelfire.com/electronic/funwithtubes/Buck_Boost.html

[Anonymous No.1149254]

>>1149252
interesting.

how much current do you need?

maybe a microwave transformer could give you what you need.
otherwise custom transformer.
would you consider switchmode?

3.5kv is ridiculous, but very interesting.

for caps I'm not sure. you could have several in series with balancing resistor..
most likely the easiest.

getting caps rated for 4kv at the capacity you need wont be easy.

interesting project, good speed and dont kill yourself.

[Anonymous No.1149255]

>>1148536
shit, >>1149252 here, never mind didn't see the vfd part...you do have a point.

[Anonymous No.1149258]

>>1149254
wow, didn't expect such a quick reply...

so far about 700mA at the minimum

I was thinking about a micro trafo but the problem is no isolation from the case, although it would provide enough to drive a voltage doubler...diodes and caps would be tough to find, it would all be custom components and very specialized which means big dollars.

don't want to be switchmode because i'm a snob and dont know shit about them to be frank.

the ridiculous thing is this tube has a transconductance of 55mA/V and u of 300. never heard of a beam triode before this but it's a neat tube, sure it will be a light show with all the electrons collecting on the glass like pic related. i might hook it up to my power supply and collect some characteristic curves to get an idea of linearity and the working relationship between electrodes but that "only" reaches 400VDC.

of course with tubes like kt88 or kt120 there really isn't a point but sometimes i like to do shit just because it would be fun.

i wonder about the sound though. probably won't be much different.

i also wonder about a primary to secondary short in the opt...that would not be cool.

it's pretty scary to fathom building this thing but it would be cool.

[Anonymous No.1149314]

after 5 ish days of working fine, the stereo i built suddenly developed some hum on left channel.

its there at the same level, no matter the input, channel or volume level.
I crosschanged tubes but the hum remained on the left channel.

it works fine, no extra heat dissipating on that channel's tubes or OT as far as i can tell.
just annoying.

it must be after the input and pot since the pot doesn't affect the hum at all.
I dread taking this down to the lab(far away) and opening this up again.

it kinda sounds like heater noise, but why would that suddenly start out of nowhere and only affect one channel?

any idea what i should look for?

[Anonymous No.1149320]

>>1149314
short the input to ground, does it go away or remain?

[Anonymous No.1149323]

>>1149320
it remains.

like i said. the hum is there no matter the channel, input or sound level.

[Anonymous No.1149324]

>>1149065

C++ ain't hard to pick up. There's libraries for most hardware you can think of, or you can just modify what is out there.

[Anonymous No.1149326]

>>1149323
check your power supply, probably a bad filter cap.

do you have a schematic? I'll have a look and see if I can come up with something.

hum usually results from either a ground loop, a bad filter capacitor in the power supply or a heater to cathode short.

[Anonymous No.1149331]

>>1149326
>check your power supply, probably a bad filter cap.
how could that only affect one channel?

i got a schem somewhere. let me have a look around.

[Anonymous No.1149383]

>>1149331
Did you already try swapping the output tubes between the left and right channels?

[Anonymous No.1149547]

>>1149383
yes.

[Anonymous No.1149553]

>>1149547
Well if it stayed in the same channel then you've ruled out a heater to cathode leak in the tube. Must be something else specific to that channel.

[Anonymous No.1149569]

>>1149553
lol, turned it on today, and now its gone.
wtf is going on?

working fine as of now, blasting some church of misery.

[Anonymous No.1149572]

>>1149314
Check the coupling caps on each stage of the channel in question. A cap leaking DC in to the next stage can cause hum. You can also pull preamp tubes to try to track it down. Start with the first preamp tube for the channel and see what happens. Pull tubes in order until the hum goes away. When it does, you've found the stage with the problem. If it's still there without the preamp tubes in, it's in the output section.

[Anonymous No.1149711]

>>1149324
I struggle with arduino

written code is not for me, LabVIEW for example is much easier because it is so much more visual

[Anonymous No.1149715]

>>1149572
cool. i look into that coupling cap thing.

this is a stereo, so there is only one dual triode per channel.

[Anonymous No.1149753]

shits back and running with no noise.

i couldn't really make sense of it. so i ripped out all the tubes.
it started humming again as soon as there was a pair of powertubes and a preamp tube in place on the left channel.

decided try the set from the other channel even though i've crosschanged 2-3 times now.
and suddenly it was fine again.

I can only conclude dirty-ass pins on my tubes, or maybe a shoddy solderjoint on one of the sockets.

i need to find one of those blue erasers, good for rubbing off corrosion without scraping off coating on the pins.
I'll have to see if i can spot some shitty soldering next time i open it up, but the way its mounted it might not be easy.

thanks for all the comments boys.

[Anonymous No.1149767]

>>1149753
looks nice

just touch up all the solder connections on that channel, takes only a few minutes but saves you a lot of headache if it is a shoddy joint

[Anonymous No.1149822]

>>1149767
thing is, my whole lab setup is a fair ways away.
but yeah. if the problem persists after cleaning up the pins and sockets, i will.

[Anonymous No.1149823]

>>1149822
yeah, the problem seems to be one socket in particular.
might be easier to bring my soldering iron here instead.

[Anonymous No.1151470]

>>1149823
>>1149823
everything looked fine, but i resoldered just about every connection on the left channel.

been fine so far after that.

[Anonymous No.1152963]

Does anyone know of any microphone preamp with phantom power designs? Preferably using 6au6 or 12au6 tubes.

I just want something that is relatively simple to make for a shitty condenser microphone.

[Anonymous No.1152988]

>>1138755
does this vacuum shit light up?
or am i thinking of nixie
if not could you fake it by neon backlight?

[Anonymous No.1153010]

>>1152988
Some tubes do that. It was mentioned somewhere in the thread that it's a mercury rectifier tube.
Well, and many normal tubes look somewhat similar when they're faulty. See >>1143051.

Some people put LEDs inside tube sockets to make them look "nicer". Can't say I'm a fan of the practice, but whatever. Pic related.

[Anonymous No.1153204]

>>1153010
>when they're faulty
This. Blue/purple glow is from gas in the tube. People find the imperfection aesthetically pleasing.

[Anonymous No.1153744]

>>1153204
Purple yes, blue it depends. I have a gassy 6201 that glows violet, and won't conduct current until the voltage is turned way up.

Blue glowing can occur when electrons strike the glass hard enough. https://www.physicsforums.com/threads/what-is-blue-glow-in-vacuum-tubes.732194/

Funny thing is, all the Sovtek 6L6GCs in one of my amps used to do it but the only one that does still is a NOS Sylvania. Another thing I've noticed that it comes back when a tube isn't used for a while.

[Anonymous No.1153809]

>>1153010
>LEDs inside tube sockets
this shit pisses me off.

[Anonymous No.1154228]

>>1143800
>>1147013
they can be seen in various movies etc., they just have a certain aesthethic that you can't really replace

[Anonymous No.1155464]

>>1138776
That is such a beautiful radio

[Anonymous No.1155481]

So i'm that anon who would have gotten a whole stash of tubes... Sadly we found out today that someone has already thrown half a cubic meter of tubes in the trash. the only thing that was left were two 10 amp 6.3 volt trannies and a tube based signal generator which i took home. later this week we will hit one more location but it is unknown what is even stocked there, it could all be crap or it could be awesome.

We did find about 10 variacs, some big some small. a whole bunch of decade boxes with the most awesome feeling switching ever and some more small general electronics goodies. I'm going to see what I take and the rest will be distributed among local enthousiasts

[Anonymous No.1155506]

Okay so all this shit you guys are posting is pretty cool and all, but where the fuck do I get started in getting into this stuff? Like I want to create a stereo amp but I don't even know where to begin in this. I have a good amount of knowledge when it comes to circuits but I can't really find any info on how to use these tubes / where to find them.

[Anonymous No.1155516]

>>1155506
Try library. Most of the decent tube-related stuff is older than Internet.
That said, it's not like people can't scan old books. You can check http://www.tubebooks.org/technical_books_online.htm or just Google relevant shit.

[Anonymous No.1155517]

>>1155506
>create
Try fixing a broken one first.

[Anonymous No.1155785]

>>1155506
there are a few designs that have been built a lot which I would recommend copying.

[Anonymous No.1155917]

>>1138755
>obsolete tech
Tell that to /mu/gg/.

[Anonymous No.1155988]

>>1155506
Pick up a copy of RCA's receiving tube manual. EBay is a good place or if you don't mind reading shit on a screen: http://www.tubebooks.org/tubedata/RC30.pdf

Read the whole preface, there's lots of good info out there as well though. Steve Bench had an interesting website and a good tutorial on how to draw load lines which is important. That book also is good for specs on tubes and ocassionally has plate characteristic curves which are great, else, just google the tube type and datasheets are easy to find.

The Radiotron Designer's Handbook is also good, but very technical and isn't really what I'd call a good beginner book but becomes increasingly useful if you decide to pursue the hobby.

I've taught myself everything I know now, kinda studied on and off 2 years whenever I felt like it. Tube amps are a piece of cake compared to some other things that can be built.

A good first step is buying a kit, learn to solder and study the diagrams. Google everything you can and learn about each component and it's function in the circuit. Just be wary voltages in a tube amp are often high and can easily fuck your shit up so you have to be cautious.

Fun WIth Tubes is also an excellent site with information for beginners as well as The Valve Wizard.

Good luck.

>>1155917
Don't need to tell me that, there's a market for shit like this so it's far from that. $200+ 12AX7s...fucking ridiculous. And for some reason guitarists rave over tube amps, but it is what it is.

[Anonymous No.1155991]

Fun little project but sadly there's not much worth listening to. Living in a city sucks for radio.

[Anonymous No.1155992]

[Anonymous No.1155993]

[Anonymous No.1155996]

Good way to wind coils, you could drop ferrite rings into the pvc and have another way to tune the receiver.

[Anonymous No.1156252]

>>1155991
>>1155992
>>1155993
Is this from popular electronics?

[Anonymous No.1156567]

>>1146972
Nice one, love the idea of using fuse caps for knobs

[Anonymous No.1156741]

Ran some tests on the first amp I built, it's a 6080 headphone amp, single ended, driven by a 6CG7.

The output transformers aren't gapped as they should be.

I thought this was going to be worse, I calculated about 15% THD on paper from the loadlines but I'm pleased.

[Anonymous No.1156756]

>>1155996
Hey that's a neat idea, got any ballpark inductance values for that? Just an anon wanting to build an analogue resonance EQ, that's all. I need to increase the capacitance or inductance by a factor of 1000 to get from a 20Hz resonance to a 20kHz resonance, and trimmer caps don't really do that. Though I can't imagine a 1000x difference. I know there are better ways of doing this, it's just a little side project.

[Anonymous No.1156955]

>>1156741
>designed it for fifteen fucking percent distortion
>pleased when distortion is only 5.5%
My head hurts.

>>1156756
It's going to be something like 220µH for L1.
You can make rough estimates for the other coils by using formula (turns/80)^2 * 220µH (80 being the number of turns in L1).

If you want to cover 3 decades, you'll need several ranges. Also, consider using RC stuff, as it requires you to change component values only proportionally (1:1000). LC filters would require a change of 1:1000000.

[Anonymous No.1156967]

>>1156741
pics of your amp?

[Anonymous No.1156984]

>>1156955
Yeah it sucks. But I wanted to make an amp with 6080, and didn't know much at the time. I calculated the result long after I built it.

Not to mention I don't have the right transformers, that tube is a current hog and I'm sure it's magnetizing the cores, not helping the situation.

>>1156967
Sorry, I don't have a better photo at the moment.>>1138784

I wish I never tore pic related apart, that would have been interesting to test.

[Anonymous No.1156988]

>>1156984
dude, sweet mercury rectifiers
I hope they never break on you

[Anonymous No.1156993]

>>1156988
Yeah that would be bad news, but even CFL have mercury, and those are everywhere.

[Anonymous No.1157054]

>>1156993
yeah but they contain not nearly as much as a mercury arc rectifier

The hazmat screw knows me by name after a certain incident at work with half a liter of mercury so I'm always a bit cautious with it.

but people show us more if you get the opportunity

[Anonymous No.1157145]

anyone happen to have a Mesa MK2C+ at hand and doesn't mind sketching out a schematic?

[Anonymous No.1157149]

>>1157145
Why don't you just Google it?

[Anonymous No.1157160]

>>1157149
some are inaccurate or partial samples
i found a few but it would be nice to compare with the real thing to see if there are any inconsistencies

[Anonymous No.1157166]

>>1157145

[Anonymous No.1158273]

Currently working on a push pull, class ab1 EL84 amplifier with a 6sn7 driver and 6sn7 cathodyne phase inverter.

Might use 6bz7 instead of 6sn7, looks like I might need the gain to drive them though, looking at 26V to drive this bastard into clipping.

Might lash up a test circuit for the preamp / PI and do some distortion measurements. Gonna try to shoot for as little as possible in those stages and then tackle the power stage, all said and done, add feedback to make it even better.

[Anonymous No.1158503]

>>1138818
Fugggg I would kill for that

[Anonymous No.1158692]

>>1158273
ooohh lala

more pics please