New Liverpool build, first fire-up

[plook]

I will make sure all ground bolts are tight.

Can you tell me a bit more about that elevated filaments wireup.

I was under fluorescent at the time of testing, but will try another location today.

[Noval_novice]

If you currently have your 6.3 V winding center tap grounded, you can move it to the cathode of one of the El84's. This will allow the 6.3 VAC to "float" on top of the ~10VDC present at the cathode. Sometimes that will reduce hum related to the heaters.

[plook]

Still no joy. Some things i have noticed:

1. When i switch the power on the hum is bad even before i throw the standby switch and before a guitar lead goes in.

2. When i switch the standby on there is hum and some hiss and something i can only describe as like a small firecracker, which is intermittent.

3. Far too much treble and not much gain, but then i am very out of practice with playing anything over 20 watts and i don't have MV or VVR on this as yet.

If i could just get rid of the hum and harsh treble it would be great.

[Fischerman]

Stupid question of the day - Where are the rectifier diodes? I'm not seeing any sort of rectifier in that pic posted earlier.

[Cliff Schecht]

Not a stupid question, I can't see 'em either..

[plook]

There are four of them but they are kind of hidden by the big filter cap. i used IN4007. Check the picture to see where they are hiding.

The amp is driving me a bit nuts. Hummmmmmmmmmm

[passfan]

Still no joy. Some things i have noticed:

1. When i switch the power on the hum is bad even before i throw the standby switch and before a guitar lead goes in.

2. When i switch the standby on there is hum and some hiss and something i can only describe as like a small firecracker, which is intermittent.

3. Far too much treble and not much gain, but then i am very out of practice with playing anything over 20 watts and i don't have MV or VVR on this as yet.

If i could just get rid of the hum and harsh treble it would be great.

Check your input jack. I'm not a big fan of the fender style shorting jack and have had them not work properly right out of the gate. If you've no cliff jack then at least star washer it to the chassis and make sure the contact shorts when you pull the jack. Your amp should be quiet with no guitar cable.

[Fischerman]

Shouldn't be getting any noise whatsoever when on Standby. Should be dead silent. Are you sure the Standby switch and power supply are wired correctly? Measure voltages while in Standby, you should get heater voltage and DC voltage up to the Standby switch but no voltage anywhere else. OT center tap should not have voltage while in Standby.

[plook]

I thought i had isolated it to the mains tranny because when i disconnected all the secondaries the tranny was humming in what i thought was a loud way, but it's within margins. When i reconnected it the noise was more profound.

When i turn down the volume pot the noise goes and all you can hear is standard tranny hum. Turn the volume up and it's noisy as hell. I'm at my wits end with it.

The input jack is good.

[plook]

I think i will take it apart and start again, maybe re-route wires. Would anybody be able to supply me with some pictures of a tidy example of a Liverpool inside the chassis so i can use that as a guide.