18Watt.com

Cathode resistors still at 150 ohms. I have 220 ohm I can try. I meant SCREENS are low sorry, ie, pin 9.

Toasty as in, I can feel warmth on my face leaning over the amp and can smell heat. No sparks or smoke. I don't know what a normal amp feels like. Should there be an increase in heat maybe thirty after flicking the amp off standby? I feel like if I patiently take all the pin voltages something bad might have happened by the time ive finished...

I'd been sort of ignoring the preamp side as ive never had any off measurements there but I will add them as ive never taken them with a full set of power tubes.

I did take ABC
A 339
B 312
C 269

About the toast.. EL84 tubes are really hot by nature. There’s no comparison with 12ax7 operational temperatures.

Maybe toast is actually ok. Took all these turning off the standby between each one.

They all look right to me. Everyone asleep now, I'll give it a blast in the morning, maybe a bit of chopstick on the lead dress is all that's needed?

Those voltages are fine. With your 150 ohm cathode resistors, you're about 90% dissipation, which is also fine. I think 220 would be too high, and we usually shoot for 85%, so you're close enough.

Play it in the morning and see how it sounds. If there are noise issues, deal with them. If not, record a demo and share it!

Something nasty/ cracky/ trashy going on in the sound. Gets worse after a few minutes, much worse higher volume. Definitely accompanied by increased heat and a smell of hot electrical stuff but maybe this is irrelevant. Eurrrgh. Anyone link me to a good trouble shooting guide to work through?

Im assuming as my voltages are good then everything is wired up in the right order at least?

Am I looking for a bad solder joint?

Tried different pre amp and pi tubes, same deal. Chopstick produced no crackling sounds of any sort with volume at 2 or 3, lead in, but no guitar connected. Some change in hum/tone moving wire to pin 2 V2 but nothing dramatic.

Power tubes glowing pretty bright, voltage doesn't seem to change, could they be red plating at the voltages posted? I know I'm flailing around in the dark now...

Pin 2 v3 and 4 is 0.16V

Pin 2 v5 and 6 is 0.03V

Doesn't seem right.

They all measure 480-490 K to ground.

chaliapin wrote: ↑

Fri 02/03/23 7:20 am

Pin 2 v3 and 4 is 0.16V

Pin 2 v5 and 6 is 0.03V

Doesn't seem right.

They all measure 480-490 K to ground.

Those are slightly high, which means the quality of the soldering between Pin 2 and the path to ground could be improved.

For your other issues, it sounds like you might have some oscillations causing trouble. Try moving more wires with the chopstick and see what response you get. Posting high res photos of your build could help too.

These are the power tubes at work. 3 and 4 are angled differently to 5 and 6.

chaliapin wrote: ↑

Fri 02/03/23 10:08 am

These are the power tubes at work. 3 and 4 are angled differently to 5 and 6.

I meant photos of the inside of the build. Photo color accuracy makes it unlikely we can tell you anything about the tube glow color. If it looks orange to you, it should be fine. The voltages implied the power tubes should be fine also.

Ok I'll stop panicking about frying my tubes.

Inputs and preamp

Pa and outputs

If it would be of some assurance : when tubes are redplating… you just unmistakably know, trust me.
Those grey metal bands plates start to glow hell fire red and look like they are being torched…

Bu the way.. didn’t you buy more than just 4 from Ukrain? Try swapping some and see if that cures the crackling

Crackling is often because of a bad solder joint. Unfortunately, a lot of what I see in the photos needs attention. Please watch the soldering videos linked in my signature, and revisit your build with a magnifying glass. Watch them again if you already have.

Im working through the joints, I'm just not convinced im making them any better...

It's not like a loose connection crackle it's a nasty noise.

Ok, did some more work with the chopstick and changed the power tubes. Plugged in and played. No nasty noises. Son was off to bed but very little overdrive with volume halfway, hb guitar (guild starfire) volume 8 or 9. Good loud clean but not what I was expecting.

With nothing in the input Jack the amp is now pretty quiet up to ten. Which is good right?

Chopstick on the p2 v2, the pi is pretty sensitive on the pin, the turret and also the 22nf cap, much more sensitive than pin 7. Is this telling me about a bad solder joint around there?

chaliapin wrote: ↑

Fri 02/03/23 4:29 pm

Ok, did some more work with the chopstick and changed the power tubes. Plugged in and played. No nasty noises. Son was off to bed but very little overdrive with volume halfway, hb guitar (guild starfire) volume 8 or 9. Good loud clean but not what I was expecting.

With nothing in the input Jack the amp is now pretty quiet up to ten. Which is good right?

Chopstick on the p2 v2, the pi is pretty sensitive on the pin, the turret and also the 22nf cap, much more sensitive than pin 7. Is this telling me about a bad solder joint around there?

Sounds like you made a lot of progress. Sometimes pins are sensitive. Look at your voltages and see how things sound. If the nasty noises are gone, move on.

You're running a 36W amp, you're going to have more headroom than an 18W amp. You'll need to crank it a bit to get the dirt, or use a signal booster on the guitar.

Thanks Josh, pretty excited, it still works this morning!

Ears ringing but at seven or eight volume it's roaring pretty nicely but I remember getting more and smoother and creamier distortion with 18 watts, and that with single coils. Also Could be hearing something a bit crunchy, treading on broken glass type sounds, in the back of the distortion but it's so loud it's hard to know what im hearing! I need a longer lead so I can play in the next room! I'll get the strat out later and see how that works.

Thanks for all the help as ever, I'm pretty close now!

You're welcome. Take your new voltages and post them again.

I recommend building an attenuator for home use: files/JMPGuitars_Break_Wind_Attenuator.pdf