Switching from 6L6 to 6550 tubes ?

[JB007]

Can i replace my 6L6 tubes for 6550 tubes with proper bias or do i have to do a special mod to make it work ? I think i'll have to change the bias resistor to get in proper range but i'm not sure if thats the only thing else i have to do. Thanks.

[harddriver]

Can i replace my 6L6 tubes for 6550 tubes with proper bias or do i have to do a special mod to make it work ? I think i'll have to change the bias resistor to get in proper range but i'm not sure if thats the only thing else i have to do. Thanks.

You'll need to check and see what bias range your amp has to see if it has enough so the 6550 can operate safely in their specified bias range.

You'll need a digital multimeter or take it to your local tech.

If your running 6l6's now you may have enough of a bias rang to run them but you need to check it out either way. Here's the bias ranges for a Marshall amp. You did not specify what amp you are using.

Bias range for(100watt amp) EL34 is -36 to -45DCV on pin 5
Bias range for(100watt amp)KT-88/6550 is -44 to -55DCV on pin 5
Bias range for (50 watt amp) EL34 is -34 to -40DCV on pin 5
Bias range for (50 watt amp) 6550/KT88 is -38 to -48 DCV on pin 5

[swid]

Sorry for thread necro, but are there any other concerns with regards to doing this? Is it safe to assume my transformers would be able to handle 6550s? I have a Sovtek Mig50 that runs really high plate voltages, so I was thinking the amp might do better with 6550s (assuming they can fit in the headbox!).

[zaphod777]

Just checked a few spec sheets. 6550's draw a fair amount more heater current(1.6 -1.8 ) than 6l6's(.8-.9), its likely not safe unless the PT has the current to spare.

[motorhead_6]

Why do you want to? What kind of change in the sound are you looking for?

I'm only asking because I have switched from 6550's to 6L6's before and liked the 6L6's better.

[demonufo]

MOST IMPORTANTLY....
What type of amp are we talking here?

[motorhead_6]

I think you were probably asking him but in case you were asking me it was a Marshall MK2 Superlead 100 watt. Somebody told me it is a 1973 but I don't know for sure. If I give you the serial number will that tell you what year it is?

[demonufo]

Yes I was asking the original poster. Just making sure we were talking Marshalls here, and not a fender circuit! Otherwise socket re-wiring may well be in order.