/diy/ - Do It Yourself

[Anonymous No.1331067]

I'm going to build pic related for playing guitar. It's an old circuit from 1947, not designed for guitar i believe.
How to make sure i won't die electrocuted while building it, or later, while using it?
How hard is it to add a secondary input, and to add bass/mid/treble controls?
Is it possible to drive the tube to distort, through increasing its tension or something?

[Anonymous No.1331072]

What happens if i change the Resistor and Capacitor values?

[Anonymous No.1331550]

you should post the source
http://audiokarma.org/forums/index.php?threads/my-first-tube-amp-check-my-work.442425/
http://audiokarma.org/forums/index.php?threads/first-tube-amp-build-job-done.443386/
you can add an isolation transformer like that guy for safety

but there are also 12V tubes and the wiring isn't much different
https://hackaday.com/2014/11/03/low-voltage-tube-amp-is-great-for-beginners/

[Anonymous No.1331560]

https://www.flickr.com/photos/wigwam/15119799365

[Anonymous No.1331564]

the specs
http://www.bunkerofdoom.com/tubes/syl43/DATA/1949/1949.HTM

[Anonymous No.1331705]

>>1331550
>>1331560
>>1331564
actually i havent seen those links/sources, i saw the circuit on a little yt vid and didnt think of reverse searching the circuit

[Anonymous No.1331756]

>>1331550
Mixing P and E tubes in the same circuit rarely makes sense:

P tubes are for 300mA series heating:
PY88 300mA/30V, PCL82 300mA/16V, combined 300mA/46V.
E tubes are for 6.3V parallel heating:
EY88 6.3V/1.55A, ECL82 6.3V/0.78A, combined 6.3V/2.33A.

A PY88 heated with 6.3V is almost unusable as a rectifier.

[Anonymous No.1331762]

>>1331756
Maybe that's the reason why it has an absurdly large filter capacitor.
Makes me wonder how long PY88 can take that misuse. Longer than the user wants to listen to that shitty amp?

[OP No.1331892]

i dont understand nothing you guys are talking about

[Anonymous No.1331936]

>>1331892
then you're not ready for it, not least because you don't appear to understand that transformers from 1947 aren't readily available
start with a shitty 12AX7 preamp like Pic related and learn from it

[Anonymous No.1331937]

>>1331936
no that amp is super simple, some goofy nerd made it
https://www.youtube.com/watch?v=ak9L4E4BtLY
it's just soldering parts together

[Anonymous No.1331939]

>>1331936
>just the preamp
boring

the transformer just converts the output impedance from 3kohm to 8ohm

[Anonymous No.1331941]

>>1331937
>that amp is super simple
about in line with OP's skills and understanding in this area teebeeaitch

[Anonymous No.1331943]

>>1331941
yeah thats why i want to build it

[Anonymous No.1331948]

>>1331939
babby's got no business building, let alone tweaking, 70 year old designs if he can't figure out how to jam in a tone stack without perforating his anus, let alone not kill himself while playing it
go back and read more theory, cowboy

[OP No.1331951]

>>1331948
ok you demotivated me, i dont want to tweak and mod it anymore.
c'mon its a simple project and i have experience soldering

>>1331943
>>1331939
>>1331937
this is me btw

[Anonymous No.1331976]

Why in gods name would you build an amp that's powered directly from AC mains? How in the fuck is it not going to self-destruct all the caps? Or is the second valve used as a rectifier? That's kind of clever, but a diode bridge is 100x cheaper than half a 12AX7 and works a billion times better. Don't bother with such old designs unless you have a historical interest in old designs. If you want something useful, use a modern design with modern tubes and components like >>1331936

>>1331939
>just the preamp, boring
That preamp could probably drive more power through a speaker even with the provided 30V supply if you replaced the volume pot, R8, and C16 with a transformer than the one you posted, which is rated for 1W. You know that's like absolutely useless as a guitar amp, right?

[Anonymous No.1331980]

>>1331976
>How in the fuck is it not going to self-destruct all the caps?
i dont know, i just know it works, check the vid >>1331937

i dont want something loud i want the cheapest possible tube circuit that i can build. 1w is ideal for me

[Anonymous No.1332119]

>>1331980
>i want the cheapest
Tube amps are not cheap. How much is the ancient 117N7GT? A vendor who has 6 pcs in stock cites $37.85 plus shipping (stay away from untested ebay crap tubes). Then you need the special octal socket, a suitable 3K:8Ω output transformer, a 1:1 mains transformer (unless you're an electrophile who loves the mains tickle your guitar will provide) and a chassis to hold it all together.

If it must be a tube amp, look for a modern, well documented kit like the MOD 102 Guitar Amp Kit. (Click here to order) .. $215 (^_^)

[Anonymous No.1332159]

get:
-8ohm output transformer with around 3k ohm on primary
-resistors and capacitors don't need to match exactly the values
-R2 and R3 have to be 1watt min
-R1 is a logarithmic potentiometer
-the voltage of capacitors should be similar
-for safety have an isolation transformer or at least a residual current device
-you can add 1.5A fuse
see >>1331560 >>1331550

[Anonymous No.1332168]

>>1332119
i found a tested tube for 18 bucks shipping included
found the socket for 15
still didnt find the 3kohm transformer and the circuit doesnt mention the 1:1 transformer

>If it must be a tube amp, look for a modern, well documented kit like the MOD 102 Guitar Amp Kit. (Click here to order) .. $215 (^_^)
i really want the cheapest, simplest, low wattage tube amp (and that doesnt allow guitar buzz, now that you said that amp buzzes). doesnt matter if it's 70yo phonograph amp.

[Anonymous No.1332169]

>>1332159
thank you! noted

[OP No.1332170]

>>1332119
i found a tested tube for 18 bucks shipping included
found the socket for 15
still didnt find the 3kohm transformer.
what specifications to look for on the 1:1 transformer? btw how does it work, if the system works with raw acdc energy

>If it must be a tube amp, look for a modern, well documented kit like the MOD 102 Guitar Amp Kit. (Click here to order) .. $215 (^_^)
i really want the cheapest, simplest, low wattage tube amp (and that doesnt allow guitar buzz, now that you said that amp buzzes). doesnt matter if it's a 70yo phonograph amp.

>>1332159
thank you! noted

[Anonymous No.1332184]

>>1332170
>the 1:1 transformer?
Tube heater has 117V 90mA (about 10W) and the rest has less than that. So a 20 or 25 watt 1:1 (in=out) isolation transformer should do. More doesn't hurt, less may get hot.
>works with raw acdc energy
The original version (your pic) was for AC or DC, either or, whatever you happened to have. DC mains is rare now.

[Anonymous No.1332185]

>>1332170
youre never going to find that transformer
heres a low powered guitar amp i built. sounds really nice.

[Anonymous No.1332186]

https://www.youtube.com/watch?v=mrMGGHp8yLk

>>1332170
might be good to get R2 and R3 close to their suggested values, preferably exact values
>still didnt find the 3kohm transformer.
based on this
http://www.radioremembered.org/outimp.htm
anything with an impedance ratio of 375:1 or wiring ratio of 19.4:1 (and 1 watt min rating) will do
(there are small chink ones on ebay but apparently only for 0.25watt)
>btw how does it work, if the system works with raw acdc energy
nothing special, the tube is just made to work on 100V, it's easier to make a tube for higher voltage and convenient since it wouldn't need an input transformer

[Anonymous No.1332203]

>>1332170
>RAW ACDC ENERGY
the right half of that 117yadda tube is a diode used as a rectifier. the left half is the tetrode used as an amplifier. the tetrode's plate is supplied via R3 and the output T

[Anonymous No.1332204]

If you get a transformer with separate windings then you could rewind it.

[Anonymous No.1332205]

>>1332170
>>1332184
>1:1 transformer
use two doorbell transformers with secondaries connected

[Anonymous No.1332210]

>>1332205
>needs a 1:1
>just use a 7:1
it's for the isolation transformer you faggot

[Anonymous No.1332214]

>>1332205
If the heater is meant for 110V you can't just put 16V on it you faggot just because the transformer is rated on 10W.

[Anonymous No.1332231]

>>1332210
>he thinks double isolation isn't better than single isolation

[Anonymous No.1332338]

tube+output+transformer
3K:8 lundahl.se toroidy.pl
too good to be cheap

[Anonymous No.1332341]

>>1331976
>>1331980
The tube is one of those tubes that has two different components in it. One part is a rectifier and the other is a pentode. That being said, wouldn't OP need at least one other tube to act as either a preamp or output?
>>1332214
I think he means placing them back to back so that the secondaries are connected like>>1332231.

[Anonymous No.1332363]

>>1332341
1 tube amps exist anon

[Anonymous No.1332414]

>>1332341
He wants no more than 1W but asked about adding bass/mid/treble controls, which would require a preamp because even without that the gain is barely enough for a guitar level input.

[Anonymous No.1332442]

>>1332414
1W tube amp is doable for guitar anon.
https://www.youtube.com/watch?v=FK2JCPvDNMg
https://www.youtube.com/watch?v=v_jc6wZnBas

[Anonymous No.1332465]

>>1332442
Can't watch. Is it done with the 117N7GT or some other (single) tube?

[Anonymous No.1332473]

>>1332465
neither is

but they exist.
this one is 1 tube 8W : https://www.youtube.com/watch?v=cVOwkRtO5s0

[Anonymous No.1332797]

u

[Anonymous No.1332965]

>>1332184
the cheapest input transformer i could find is 23 bucks, this little amp isn't cheap anymore. but any other amp design will need a isolation transformer for safety and avoiding noise, so i have no cheaper circuit to chose. is that correct?

>>1332185
>youre never going to find that transformer
>wojak.jpg
i like these "tweaker notes" functions.
that amp is two tubes and quite a few watts, isnt it? 10w is too loud to crank at home, and that circuit looks quite big and expensiver.

>>1332186
thanks, i guess ill have to do a bit of market research for an output transformer

>>1332203
i understand nothing

>>1332204
itd be nice to rewind something. what would be that for?

>>1332338
yeah this is getting quite pricey.

[Anonymous No.1332981]

>>1332965
> itd be nice to rewind something. what would be that for?

Well, let's just say it's not like rewinding a VHS tape. pro tip: you're gonna need a hammer, a flat screwdriver, a steady hand and patience

[Anonymous No.1332982]

>>1332981
ah. i was just curious, i guess doing that wouldnt help on this project huh

[Anonymous No.1332987]

>>1332982
Nothing seems to help, you have so many ppl telling you not to do it, recommending better schematics etc etc but you 're still stuck. I recommend taking the hard route and do more reading.
I did my 1st guitar amp from a published schematic ( ax84.com) but for the next 2 (stereo tube amps) I made my own schematic

[Anonymous No.1332988]

>>1332987
but any other schematic would be expensiver

>Nothing seems to help
is that a complaint

[Anonymous No.1332995]

>>1332988
I recommend taking apart an old tube radio and use the chassis, transformers and loudspeaker.
Pick one that has 2 transformers inside, so it has actually a power transformer. Raid grandma's house?

[Anonymous No.1333011]

>>1332995
the cheapest working old tube radios here are like 200usd

[Anonymous No.1333013]

>>1331550
why adding a transformer improves safety? what the transformer even does, since it's not converting voltage or anything

[Anonymous No.1333032]

>>1332965
I would look for a single tube amp based on the ECL82=6BM8 like the one at http://www.lh-electric.net/projects/tiny3w.html

The output transformer (P-T31) is $13.95 which is reasonable (about the price of the tube) but the recommended mains (also isolation) transformer (P-T261G6) is $43.93 which seems too much because it is too big. The ECL82 heater only needs 6.3V/780mA (not 2A) and the anode current is less than 50mA. There should be a smaller and cheaper mains transformer in the price range of tube + output trafo available elsewhere.

>>1332995
While not exactly DIY this would be the cheapest possible option: a still functioning tube radio that has a phono input.

[Anonymous No.1333033]

>>1333032

>While not exactly DIY this would be the cheapest possible option: a still functioning tube radio that has a phono input.
the working ones on local sites arent actually cheap :(

>>1333013
doesnt an external line filter, like those people use on computers, do the same job of fixing huge shock risks and 60hz noise?

[Anonymous No.1333034]

>>1333032

>>1333013 ??

>While not exactly DIY this would be the cheapest possible option: a still functioning tube radio that has a phono input.
the working ones on local sites arent actually cheap :(

doesnt an external line filter, like those people use on computers, do the same job of fixing huge shock risks and 60hz noise?

[Anonymous No.1333040]

>>1333013
Feeding circuits directly from the mains
http://www.dos4ever.com/TiT/TiT.html

[Anonymous No.1333045]

>>1333034
No, line filters are transparent for the mains voltage.

[Anonymous No.1333048]

>>1333040
does that mean playing guitar plugged to that device is like connecting the guitar strings directly to the power plug?

>>1333045
would it bother you to explain why/how?

[Anonymous No.1333061]

>>1333048
Look at the OP pic and follow the path from the (reversible!) mains plug to the input socket J you can touch. Only capacitor C-1 and resistor R-1 are between you and the line. Have you never felt the typical tickle?

[Anonymous No.1333071]

>>1333061
lol. yeah i feel weak shocks when playing guitar with bare feet at regular guitar amps. idk why it's weaker than 110v. and why a 1:1 transformer fixes the OP circuit?
>reversible!
how

whats with that pic
>attenuate conducted radio frequenies, interference
why does that not fix the 60hz noise

[Anonymous No.1333076]

Good midnight

[Anonymous No.1333079]

>>1333048
>does that mean playing guitar plugged to that device is like connecting the guitar strings directly to the power plug?
Yes if you plug it in wrong (you don't know the right way to stick the plug in, and you have a 50/50 chance of sticking it in right).

[Anonymous No.1333081]

>>1333076
wut

[Anonymous No.1333087]

>>1333079
you mean soldering the jack? what can go wrong? not grounding it?

[Anonymous No.1333132]

>>1331067
I've got a one tube amplifier schematic I traced somewhere OP. It pushed 1-3 watts and had a triode preamp and pentode poweramp in one valve.

Idk if your pentode there is going to be too exciting by itself or safe without isolation.

[Anonymous No.1333134]

>>1333132
preamp and poweramp both in one valve? excuse me my english isnt very good. i'm interested on that amplifier design.
>or safe without isolation
i'm worried about that. you can't isolate it because the guitar strings are metal and connected to the audio signal path that goes to the amp;;; does that mean one will get a 110v shock when playing through that amp or what

[Anonymous No.1333140]

why playing guitar to the OP design isnt lethal as soon as you touch the guitar strings and why an input transformer fixes that?

[Anonymous No.1333324]

>>1332965
>itd be nice to rewind something. what would be that for?
the output tf to adjust the ratio and so the impedance

[Anonymous No.1333350]

>>1331067
>I'm going to build..
An understanding of the dangers of electricity is required to build this amp. It has been built by a number of people with no previous experience. A few survived.

[Anonymous No.1333386]

>>1332965
>that amp is two tubes and quite a few watts, isnt it? 10w is too loud to crank at home, and that circuit looks quite big and expensiver.

its only about 1.5W. I play it through a 10" in my small condo. use the dial on the amp to adjust gain, use the volume knobs on the guitar for volume. you could build it for quite cheap if you just ordered all the cheapest possible components from digikey. the transformers are the most expensive part as usual

[Anonymous No.1333729]

>>1333386
Thanks for posting the TriFly schematic. This is the simplest push-pull PA I've ever seen.

[Anonymous No.1334355]

>>1333134
It's like the other anons have been discussing the power transformers. Aside from stepping up your supply voltage, PTs provide galvanic isolation. So if you have an earth ground properly bolted to the chassis and a PT, your body is not going to become the ground through your guitar.

I'll up the schematic trace later on tonight.

[Anonymous No.1334364]

>>1334355
but on every guitar, the ground is conected to the strings

[Anonymous No.1335240]

bump

[Anonymous No.1335403]

>>1334364
Yeah, you're touching that guitar ground. In modern amps the input jack is insulated so this ground circuit is floating. In older amps the chassis is part of that guitar ground, so it's important that we bolt an earth ground to the chassis. It's good practice in the rare event that a connection were to break inside of the amp and short to chassis. Current is going to pour through that earth ground instead of your guitar and hands.

With a PT, the current in the amplifier has no affinity for earth ground. This is because the amp's current is only a reflected force from the secondary of the transformer. All the main's AC remains on the primary side of the transformer.

In your OP schematic, it's only a capacitor and resistor protecting you from main's voltage. This is not good design for a guitar amp. Anyone who has been bit by something like this, myself included, won't play on this kind of a circuit.

[Anonymous No.1335441]

I copied that practice amp tracing to paint. Sorry I didn't write down the original pin-out voltages. Neither half of the tube wants to see more than 300v. You're going to get around 3 watts if you're up there. Cathode resistors may need adjusted if you aim for lower voltages and output wattage. The original amp used a half wave recto and I just drew up a FWB recto, so instead of 40/40/40uF 20/10/10uF should be fine in the supply (rated 350v or higher of course).

It sounds like the old Harmony and Alamo practice amps. Your epiphone valve jrs, fender 5f1s, and the lot aren't too distant.

[Anonymous No.1335563]

>>1335403
>in the rare event that a connection were to break inside of the amp and short to chassis
Not him but the plugs in my house dont have grounds, does that mean I will die when that happen on my modern tube amp?

[Anonymous No.1335675]

>>1335441
thanks. what exactly i have know that is not on the .jpg? i can't guess by what you wrote.

[Anonymous No.1335743]

>>1335675
>have to know
fixed

[Anonymous No.1335996]

>>1335563
Of course not, that's why they use insulated jacks and don't chassis ground the guitar. So there's the extra layer of fail-safe.

When only a microphone or older guitar rig sees earth ground, there have been issues.

>>1335675
I didn't draw in the most important ground. You'll need to track down some appropriate transformers and a speaker. This amp is kind of a novelty in how simple and compact it is. However, It wouldn't take a lot more time or material to make a larger amp that you could use with a band.

[Anonymous No.1336107]

>>1335441
wtf are 9-2 pins used for?

[Anonymous No.1336130]

>>1336107
Triode section, preamp, anode and cathode.

[Anonymous No.1336131]

>>1336107
preamp

[Anonymous No.1336159]

stop with these silly circuits and build a real tube amp.
start simple with a el84 single ended. like orange ad5 or something.

look at ax84.com.

its not hard, just dont be a retard.
use proper transformers, caps with voltages a good 50v higher than HT or more.

dont power it without a load
step back when you turn it on or the first time.
and wear ear protection self oscillation can be loud.


my first build was a 16w daisycutter.
think my thread on it might still be in an archive somewhere.

[Anonymous No.1336162]

>>1336159
thanks anon but i'm looking for a super weak and small amp that i can turn up to 10 to get saturation. i have a 10w tube amp but can't get poweramp tube saturation at home

[Anonymous No.1336165]

>>1336162
of course you can

[Anonymous No.1336181]

>>1336165
cheaper than the cheapest tube
both amp and speaker always see 8Ω
https://www.parts-express.com/cat/speaker-l-pads/306

[Anonymous No.1336224]

>>1336181
what
i learned good sounding cheap attenuators dont exist

[Anonymous No.1336253]

>>1336224
'good' is subjective and opinions are a dime a dozen
nothing is more convincing than finding out on your own
more about L-pads: http://www.bcae1.com/lpad.htm

[Anonymous No.1336910]

>>1336162
if that's all you want, a two-triode pre running at 24V feeding a fucking 10W Crate solid state PA would do

[Anonymous No.1336943]

>>1336910
>solid state PA
how that would give power tube saturation
thats what i not want

[Anonymous No.1337028]

>>1336943
If you want the sound of power at low volume, you need to produce the power and then absorb most of it on its way to your speaker.

[Anonymous No.1337032]

>>1337028
>>1336910
a solid state PA is solid state it cant do tube saturation

[Anonymous No.1337042]

>>1336943
>>1337032
then TriFly it is

[Anonymous No.1337275]

>>1336162
clipping in the power section is overrated, not practical and a meme.
Getting the sweet tone you want, but only at a specific volume while hammering your outputtransformer is stupid.

build a high gain preamp with the crunch/gain/OD you want and put on a simple SE power section.

you can easily get great overdrive without ever maxing the power section.

[Anonymous No.1337278]

>>1336181
>fucking with the load impedance
>shifted load impedance is reflected in primary impedance of the transformer.
>my is my bias point all fucked up??

[Anonymous No.1337301]

>>1337275
yes the tone i get with my amp at low volume is good but surely the power saturation isnt a meme and i like the effect and want it on my recordings.

[Anonymous No.1337417]

>>1337278
The entire point of the device is that the load isn't effected.

>I was only pretending to be retarded.

[Anonymous No.1337624]

>>1331067
You'll never be able to make this without electrocuting yourself. In electric guitars, one wrong move equals certain death. Have you heard the volume of sound these can put out? I mean Jesus Christ man, at least get life insurance

[Anonymous No.1337747]

>>1337624
>You'll never be able to make this without electrocuting yourself
why

[Anonymous No.1337763]

>>1337747
Because OP cannot be trusted to tell which prong of the outlet is the live one, each and every time he plugs it in.

[Anonymous No.1337765]

>>1337763
can it be tested with a multimeter or something each time instead of touching to see if you'll be eletrocuted or not

[Anonymous No.1337773]

>>1337765
Sure, there are test screwdrivers that light up, too. Simpler. But would you expect a random person to do that every time?

[Anonymous No.1337776]

>>1337765
But there's no need to waste time on that war time wonder. Several better options, including fixed version of OP's circuit, have been posted.

[Anonymous No.1337791]

>>1337773
hed be aware of it and remember to do it every time

>>1337776
what does that fixed version consist of

[Anonymous No.1337821]

>>1337776
I can think of several "fixed" (AKA not retarded) versions that run on 9v with the same result that are completely embedded in the guitar if you want

[Anonymous No.1337831]

>>1331948

>kill yourself
>with 110v

How?

[Anonymous No.1337837]

>>1337773
The input combo 10n/1M of OP's amp has about the same current as a line tester. If you can't stand 0.5mA, reverse the plug.

[Anonymous No.1337894]

>>1337837
Well you see, you get the "line tester" level when you plug it correctly. If you plug it incorrectly.... poof!

[Anonymous No.1337924]

>>1337894
>Well you see
No, I don't. Where's the 'poof' current path to the input J?

[Anonymous No.1337928]

>>1337924
Simplified input circuit.

[Anonymous No.1339262]

>>1337417
how on earth did you come to that conclusion?

[Anonymous No.1339320]

>>1339262
I could explain this to you, but seeing how well spoonfeeding has gone in this thread.


"L-pads adjust the relative volume of drivers connected to them by placing added resistance in series and parallel, KEEPING IMPEDANCE A CONSTANT 8 OHM LOAD. This L-pad is rated at 100 watts RMS, is designed to be used with 8 ohm loads, features a 3/8" shaft length, and comes with mounting hardware."

[Anonymous No.1339397]

>>1339262
www.tedweber.com/webervst/lpad.htm
One use for an L-Pad attenuator is to be able to crank your amp into power tube distortion, and then reduce the power to the speaker to a comfortable level.
Some people add a small treble-boost capacitor (non-polarized, 2µ2 .. 10µ).

[Anonymous No.1339409]

>>1331067
>How to make sure i won't die electrocuted while building it,
don't connect power while building it

[Anonymous No.1339457]

>>1339409
then if i dont want to die electrocuted while playing it, i do the same?

[Anonymous No.1339553]

>>1339457
no need, simply wear rubber gloves

[Anonymous No.1339598]

Holy shit, I wouldn't build that unless I was planning to electrocute myself. Isolation transformers aren't expensive and it could save you from an embarrassing death.

[Anonymous No.1339599]

>AC/DC AMPLIFIER

There's why there's no isolation tx, it's so old it was designed for use where there might be a DC mains supply.

[Anonymous No.1339604]

can someone find a circuit made a few decades later that is just as cheap easy and weak but safe

[Anonymous No.1339611]

>>1339599
Also for saving some money. It was a common practice long after DC mains became obsolete/rare. Typically C-1 would be a safety-rated capacitor so that it fails open instead of zapping the user.

[Anonymous No.1339615]

>>1339611
can a fuse be added to OP's circuit and do that instead of adding a pricey transformer

[Anonymous No.1339682]

Normal people know, from childhood on, what electricity feels like and what it can do. The exception are overprotected ('leashed') children. They have been denied the experience that builds common sense and behavioral repertoire. They live in permanent imaginary fear. Condemned to develop mental autoimmune symptoms they are unable to react adequately to anything unexpected. Unprepared for the dangers of life, they become prime candidates for the Darwin Award. Scroll back to discover examples.

[Anonymous No.1339718]

>>1339682
????
very good text and effort though

[Anonymous No.1339757]

>>1333350
>177 V AC
>or DC
>or whatever the fuck you want really
>I'm just a schematic, not your boss

[Anonymous No.1339807]

>>1339682
you just described social anxiety

[Anonymous No.1340400]

>>1331067
Sam, are you evading your ban you got on /mu/?

[Anonymous No.1341424]

If D.C. voltage is available it may be necessary to reverse the power plug if the amplifier will not operate.

[Anonymous No.1342902]

Could you guys give me some advice possibly? I'm thinking of building an amp based on one of 60's student amps that used aa5 tubes, and am looking for an ouput transformer. The circuit that I plan on using uses a 50c5 as an output tube, and I plan on using an 8 ohm speaker. The 50c5 has a plate resistance of 2500 ohms, sqrt (2500/8) gives 17.68, which is roughly an 18:1 turns ratio. (I got the formula from here http://www.radioremembered.org/outimp.htm).). This also seems to line up with the information over here http://www.eham.net/ehamforum/smf/index.php?topic=97071.0, mainly the 6.3V filament transformer being used. I was thinking of possibly using the tr-006 listed here http://www.philmore-datak.com/mc/Page%20259.pdf or the 12v transformer here https://www.aliexpress.com/item/i/32843121437.html.. Is there anywhere where I fucked up?

Just for reference, this is the type of tube arrangement (same set of tubes) that I am planning on using (my amp will probably have an isolation power transformer though. It's most likely going to just sit in the same corner of my room plugged into the same outlet which I know is wired up properly, but I figure that it is worth the peace of mind getting one).

https://www.youtube.com/watch?v=EatwUtG2wZE

[Anonymous No.1342906]

>>1331951
Don't ask questions, fail to understand the conversation and then say how simple it is. You are playing with mains voltages, you will fuck yourself up. Do something else first before you try to shoehorn a speaker amplifier into a guitar amp.

[Anonymous No.1342963]

>>1342902
I once tried using a normal mains transformer as an output transformer of an old radio. I calculated the required voltage in a similar manner as you did.
It worked, but the frequency response ended in 1.5 - 2kHz. It was very difficult to understand what people were saying. So yeah, it certainly was "lo-fi" like your links say.

[Anonymous No.1343237]

>>1342902
110/6.3=17.5 would be close enough for a 50C5. Real audio transformers sound much better though. I do understand why tubes but I don't understand the attraction of vintage tubes.

[Anonymous No.1343466]

>>1342902
Something like this?

[Anonymous No.1344222]

>>1343466
Did they really need the snubber across the OT?

[Anonymous No.1344357]

>>1343466
Not quite. Pic related is what I'm going for, minus the transformer at the 12au6. There are a lot of circuits based on this set of tubes and similar, and there isn't too much that is different about them. I'm probably gonna experiment a little bit.

[Anonymous No.1344519]

>>1344357
Fortunately all three tubes have the same heating current (150mA).
>>1344222
Not exactly a snubber (= RC network to absorb switching transients). Maybe the amp was originally used in radios where you could get a feedback to the built-in antenna coil when the radio was turned up so loud that the PA generates harmonics up to that range. The 1n capacitor limits that. Even the LM386 data sheet has something about that situation for portable radios.

[Anonymous No.1344755]

>>1344519
I would expect an audible difference in treble with the cap installed.

That thing's interesting. Half wave recto with a chunky resevoir. Then you've got a low load line with the 1M on the first plate. For better or worse, the thread is full of oddities.

[Anonymous No.1344815]

>>1344755
>audible difference in treble
50C5 output load = 2.5 kΩ, C = 1nF, f = 63 kHz.
>Half wave recto
Tube fans love the sound of 60Hz.
>1M on the first plate
1M goes to screen grid I think, not plate.

[Anonymous No.1346818]

>>1331067

[Anonymous No.1347720]

>>1342963
>>1343237
Just wondering, what exactly makes an output transformer more suited for it's job compared to a mains transformer with the same turns ratio? I would guess that it has something to do with the amount of turns, but I haven't been able to find an explanation online.

[Anonymous No.1347782]

>>1347720
They have better core material, more layers, alternate lamination, air gap etc. to extend the frequency range and handle the anode current (see pic). Mains transformers are optimized for 50/60Hz with no DC component.

[Anonymous No.1347828]

I see the thread is changing ways to another builder so I ask what is the consensus for OP?

[Anonymous No.1347880]

>>1347828
He concluded that tube amps are not cheap.