670 dripv3 few issues left

Hi guys!

I got a few issues left with my drip 670v3.

Trying to find a solution for the noise my HV choke makes in my 670 (dripv3).
(rattles when current increases/decreases more or less compression)

Sowter told me to make the resevoir cap (4,0uf) bigger. and add a parralel 0.5uf for hf.
or to open up the tranny and fill it with rubber, because sometimes the casing could
be resonating.. maybe the JJ tubes draw a bit more current then the original ones?

what about customizing attack times, i'd like to have an option for longer attack times?

what about inserting a highpass filter, where in the sidechain?

seems that the unit rolls off about 1.5 db from 60hz and down. drip told me to try
put a 1UF across the high windings of the control amp tranny. i cant follow the schematic
with the pcb very well, anyone knows where that is located?

last week i switched the unit off and fairly quick back on, that blew some fuses!
from the heaters and it's mains fuse. i replaced them and its fine again. Do
tubes draw crazy current when they're hot?  it was kinda scary...

schrobbelbop said:

Trying to find a solution for the noise my HV choke makes in my 670 (dripv3).
(rattles when current increases/decreases more or less compression)

last week i switched the unit off and fairly quick back on, that blew some fuses!
from the heaters and it's mains fuse. i replaced them and its fine again. Do
tubes draw crazy current when they're hot?  it was kinda scary...

Click to expand...

When tubes are cold they draw more heater current , but the current in the tube will not start to flow until the heaters are warmed up. It sounds like your tubes are drawing more current then they are supposed to, putting a strain on the choke. Not the heaters mind you but the current through the tubes. Measure the current at the center tap of your output transformer and ask drip if the value is correct.

I don't know if you know but measuring current is different than measuring voltage. You must "break" the circuit and put the multi-meter between the "break". Make sure the multi-meter is set to amps first and hooked up in the circuit before you turn it on.

With the multi-meter inserted between the B+ (high voltage) and the center tap of the output transformer, you should see the multi-meter reading start to go up in mA's as the unit warms up. it will eventually stop going up and that's your reading.

On most multi-meters you will have to move the test lead from volt/ohms to amps.

Be careful, and good luck...

Don't i need to measure between the HV choke?

d.c. distortion while compressing on one channel was fixed by shuffling the 6368's and rebalance them..

schrobbelbop said:

Don't i need to measure between the HV choke?

Click to expand...

You could do that too. Measuring the individual output transformers separately can tell you which side is drawing more current.  You can compare one side to another.
But If you just checked the over all HV current draw, like you suggest,  I'm sure Drip could tell you if it was excessive or not.
You can also just check the voltage at the tube grids. Maybe they are more positive than they are suppose to be at idle which would cause the tube to suck more current than they are supposed to.
I would think they have some voltages on the Drip schematic you can compare with?

If your using JJ 6386 They can be a little off. Triodes not matched as good as they should be. So yes switching them around till you get the least "thump" or "flutter" with a lot of compression on a drum track is a good way to match them.