Preamp Tube Spots (V1, V2, etc.)

[theapprentice]

Hello everyone, I just got my very first tube amp, a Laney LC50-II, which has 4 12AX7s and 2 EL34Bs. I was browsing through the manual while checking out some jemsite threads, when I found a page in the amp manual about the tube sockets being labelled V1 through V4 for the preamp tubes and V5 and V6 for the power section. Now, I found some threads here talking about how 'this' 12AX7 is good for V1 while 'that' 12AX7 is better for V2 and so on.

What exactly do these positions do for a tube amp? I admit that I am a complete beginner when it comes to more technical aspects of the tube amplifier, so please enlighten me.

[guitar-turk]

Originally Posted by theapprentice

Hello everyone, I just got my very first tube amp, a Laney LC50-II, which has 4 12AX7s and 2 EL34Bs. I was browsing through the manual while checking out some jemsite threads, when I found a page in the amp manual about the tube sockets being labelled V1 through V4 for the preamp tubes and V5 and V6 for the power section. Now, I found some threads here talking about how 'this' 12AX7 is good for V1 while 'that' 12AX7 is better for V2 and so on.

What exactly do these positions do for a tube amp? I admit that I am a complete beginner when it comes to more technical aspects of the tube amplifier, so please enlighten me.

first the similar manual is here

at laney site lc50-112
download manual

you could see it easly that your amp is similer to this amps manual.go to page 13(block diagram)
and walla....
half of v1 is v1b:is common part for both drive and clean chanel
half of v1 for(v1a) and v3 tubes for drive chanel
v2 is for clean chanel only...
v4is phase invertor section for power amp

now if you like puncy distortions and chimmy cleans---i have an advise for you about tubes

for v1--use ultra low micraponics and noiseless tube this means low noise and micraphonics selected and tested jj ecc83-this tube gives you hi gain apart and musical defination on both cleans and drive but expecially drive channel...

for v2--use much more musical tubes for this chanel it doesn't matter hi gain or not..but my advise is tungsol ecc83 or jjecc 803 tubes.both of them are dynamic but ecc 803 is little bassy

forv3--use hi gain selected tungsol ecc83-thats the way to get an hi gain drive cascade..or you may pick eh 12ax7 lps for less his.but you absolutly lose the mids and defination.all the time i chose tungsol for drive channels.low noise hi gain and much musical balanced tones

for v4-this is an importand point..v4 is a signal diveder and drives the power tubes.this tube must be mached triod.because mached triod tube could drive power tubes at the same ratio..this will increase the power tube life-much musical sound and better defination.
and you may use 12 at7 or ecc82 for this state if you can not find mached triode 12ax7 or ecc83.you get lower volume from amp but you will be in the security and quality area..

stay cool and experiment with your own..welcome to the tube jungle
cihan

[theapprentice]

Hey guitar-turk, thank you so much for taking your time looking for the amp's manual and explaining to me the purpose of each tube socket! I actually wanted to use Tung-Sol tubes on all preamp sockets, but the V4 position made me worry and think a bit. Doesn't power tube biasing already solve the matching issue?

[guitar-turk]

Originally Posted by theapprentice

Hey guitar-turk, thank you so much for taking your time looking for the amp's manual and explaining to me the purpose of each tube socket! I actually wanted to use Tung-Sol tubes on all preamp sockets, but the V4 position made me worry and think a bit. Doesn't power tube biasing already solve the matching issue?

tube biasing is all about the current flow on the power tubes(both of 2 or 4 etc.. power tubes but not separetly)but mached triode phase invertor divides the pach to equal forms for each tubes or each tube group(sometimes there are 2 groups of power for each 4 tubes in 100 watt amps).so if something wrong in v4 your amps performance sucks..maybe alot of people don't care this situation but have to.i have many many tubes amps in my home and built lot of tube amps for my friends.we play 4 hours a day and power tubes last 2 years for us.thats why mached triode phase invertor (named v4 in your amp) is important..

use mached triode tungsol ecc83 or 12 ax7..if you could not find ---use 12 at7 or ecc82 also this tubes are esed for phase invertors..another idea they are pre mached tubes for their situation..low gain balanced triode..

and you welcome..all of us are here to help eachother so no need to thank