5e3 build super low output??

[mbailey]

okay I just finished my 5e3 kit from Triode. everything went smooth all the way thru start up. but it has very low output. what I can hear sounds okay it's just way to low. voltages check out I'm checking to see if I missed something but any help will be preciated!!

[tubeswell]

triple check your wiring and componentry against the layout diagram and use your DMM R-meter to check for continuity (with the amp switched off and unplugged) between all the points that should be connected. You may've missed a wire somewhere or possibly wired it wrong. Also you may need to reflow the solder on some of your eyelets/turrets.

[mbailey]

ok I figured out my problem. I put individual jacks for the 4,8,and16 ohm output and tied the switches to ground anyway the amp sounds killer but hums like a MOFO. I've spent the last few day moving grounds fooling with lead dress but to no avail. still trying to figure it out! any thoughts I'll listen.

[dwhutchens]

Does your power transformer have a center tap to ground for the 6.3v heaters. If not did you put a 100ohm resistor from each side of the heater circuit to ground or to the top of the power tubes cathode resistor?

[mbailey]

yes it is center tapped I have it connected to the power tube cathodes

[dwhutchens]

Have you tried grounding it to a PT bolt to see if it makes a difference. Is the hum affected by the volume control? Does grounding the first preamp tube grid make it go away?

[mbailey]

Have you tried grounding it to a PT bolt to see if it makes a difference.

yes,no difference

Is the hum affected by the volume control?

yes goes away when volume is lowered

Does grounding the first preamp tube grid make it go away?

no!!
I just re did my filament wires and it made no difference. It's gonna feel real good when I figure this out

[loudthud]

Does the hum instantly go away when the amp is put in standby mode, or does the hum fade out over a period of a second or two? (If you don't have a standby switch, use a rag to pull the 5Y3, while the amp is operating.) Are all the filter cap's grounds connected together on the eyelet board (that can cause hum).

[mbailey]

Does the hum instantly go away when the amp is put in standby mode, or does the hum fade out over a period of a second or two?

it goes away instantly

Are all the filter cap's grounds connected together on the eyelet board (that can cause hum).

the preamp filter is at a seperate ground point than the b+ and screen grid caps but the last 2 are connected together
I've shielded the input wires from the jacks to the 68k res. and from said res. to the tube still hums. I've lifted the inputs from the chassis also no change.
as I said before its gonna feel real good when I figure this out!!

[loudthud]

it goes away instantly

This suggests that the hum comes from the rectifier current pulses that flow from the transformer, thru the rectifier, the standby switch, the first filter cap, thru the ground wire of the first filter cap, thru the chassis and back to the red wire with the yellow stripe.

Any hum that comes from the heaters or input wiring will fade out when the amp is placed in standby mode.

In general, move the ground of the first filter cap and the red/yellow wire closer together (or at the same point) and the ground for the preamp filter further away. At the same time one would like the ground wire from the first cap to the chassis not to be any longer than necessary.

[mbailey]

In general, move the ground of the first filter cap and the red/yellow wire closer together (or at the same point) and the ground for the preamp filter further away. At the same time one would like the ground wire from the first cap to the chassis not to be any longer than necessary.

Ok I tried what you suggested changed all my filter cap grounds still hummin' do you think this could be a bad component and if so where would you start? I've tried different tubes of course!

[mbailey]

I don't know how much this helps but I'm pretty sure it's 60 hz

[loudthud]

Many times hum is a combination of 60Hz and 120Hz. Moving the heater CT to a positive voltage like the cathodes of the 6V6s will only reduce the 60Hz component. It sounds like a low organ note. 60Hz can also be picked up by wires too close to the heater wiring. But the 60Hz will fade slowly when you put the amp in standby mode.

The 120Hz is usually a buzz type sound that comes from the power supply. Sometimes moving the red/yellow wire from the chassis to the ground side of the first filter cap will reduce the buzz.

The next place to look is how the input stage and the rest of the preamp is grounded. Can you post a picture or a link to a diagram you followed?

For bad components the first place to look besides tubes is the filter caps. If you have a spare, tack it across the first filter to see if it changes anything.

[mbailey]

here is a link to the layout I started with but I have moved alot of grounds around trying to get rid of that hum
I tried the extra cap trick and it made no difference
http://site.triodestore.com/5E3_Layout_Diagram.bmp

[loudthud]

Please look thru the following threads. They deal with some of the issues that can cause hum. Pay attention to ground and input jack problems.

http://music-electronics-forum.com/t12663/
http://music-electronics-forum.com/t13912/
http://music-electronics-forum.com/t13689/