Deathcap X2

[wscrane]

Why would this amp come with one on each side of the power cord then?

The theory behind using two caps is is that you accept some hum (voltage-wise its exactly in-between the worst and best case) for the simplicity of getting the same result regardless of plug orientation and not needing a polarity switch. I've only seen it in cheap low gain amps.

[Structo]

Well,

After a more testing, I really couldn't tell much difference with the cap added back. I guess I wasn't quite awake when I tried it this morning before work - amp was laying with speaker facing the floor which pretty much wipes out the highs.....

I should have mentioned that in addition to rewiring the three three prong plug correctly, I also replaced some coupling caps. Originals were Sprague black beauties,replace with Sprague atoms. I also replaced the rectifier tube - the voltage was uneven and below specs on the first one, changing it put the readings pretty much right on target. C1 and C2 are pretty much dead on spec, but c3 is reading about 189 v should be 200 per the schematics. The voltages were about 10 - 15% low on the original first rectifier.

I had replaced the filter caps a while back, just used three Webers for in place of the original paper can 3 in one type type sprague - really couldn't tell much difference. The ice picky type sound didn't show up until I rewired the plug and replace the some of the coupling caps. Not sure why its so ice picky now.

Will post the results if I find the problem.

thanks.
sunnydaze

The filter caps shouldn't affect the tone per say as long as you replaced them with values that are close.

The coupling or bypass caps on the other hand can influence tone tremendously.
Different kinds of dielectric and other factors as well as the actual value may play a role.
Sometimes we get used to the sound of a worn out amp that has had the values drift with time and heat, turning it into a mellow brown sound.
So we re-cap it and wonder why it sounds different.

Usually most people replace only the electrolytic caps such as the filter, bypass and bias caps.

The coupling caps are usually a film type cap and they aren't as susceptible to failure.

[M Fowler]

I don't where I have been while this thread was going on but better late than never.

Back in the day I was using my Fender and my friend had an Ampeg. We got shocked so many times we had to force each other to take the singing chore on the next song coming up. After the last gig I had enough and said load that crap Ampeg into my truck I am going to put three prong cords on these amps. Never had a problem with the mikes biting back after that.

Mark

[sunnydaze]

Well, I guess I got back to a pretty decent tone.

Ended up going back to the rectifier tube that was a putting out a little on the low side. The amp's got a more round sound with the voltages a little on the low side compared to the schematics.

sunnydaze

[wscrane]

Nobody asked, but some more thoughts...

The reactance of a .02 uF cap at 60 Hz is about 100 kOhms. So even if you were soaking wet and touched a "hot" chassis, (such as the Alamo mentioned above) the current through the cap shouldn't exceed about 1 mA.

Although its annoying when you get it on the lip, its not an electrocution hazard. OSHA calls 1 mA a "faint tingle."

Also I think johnhenry already mentioned this but for people who may not know, the purpose of those caps is to cut hum by ac-grounding the chassis to the neutral side of of the incoming power line. If you don't do this you will have ac on your supply ground. (Maybe somebody here knows better, but I always figured the source of the ac was asymmetry in interwinding capacitances in the power transformer.)

[Bob-I]

Gee Dad, why do they call it a "death cap"?
I'm not as bright as I pretend to be so I reset the outlet and tried again, same result. O.k.

Reminds me of an old IT vendor joke. I work in a sales company who supplies mass storage for computer rooms.

4 people were driving home from a customer visit. A manager, a sales rep, a software engineer and a customer engineer (hardware repairman)

On the way down a mountain road the car's brakes failed. After an almost deadly ride down the mountain the driver finally found an uphill ramp to stop the car.

The manager got out his notebook and started taking control. "We'll form teams, analize the data, and in a few months we'll be able to fix the brakes.

He turned to the sales rep for his input but he was on the phone with the factory asking when the next revision of brakes would be available

He turned to the CE but he already has his tool out and was under the car fixing the brakes

The software engineer said "Stop everything... we need to push the car back up the mountain and duplicate the problem"

[Bob-I]

And the moral of the story is... if it happened the first time, it's gonna happen the second.

[briane]

The software engineer said "Stop everything... we need to push the car back up the mountain and duplicate the problem"

funny....I'm a software engineer by trade...We always say if you can repo it, you can fix it....

So yes, push the car back up the hill and make sure it was failed brakes, not the driving pressing on the clutch thinking it was the brake.