Changing powertubes Twin Reverb 1974

[Auke Jolman]

Hi All,

I've got a 1974 Twin Reverb which I blackfaced some time ago and did change all the e-caps. I also took out the MV. I'm thinking of changing the power tubes from 4 6L6 to 2 6V6. Furthermore I would like the amp to break up sooner.

I realize I have to change the OT and the bias. What would be the best OT for this. What are the other things to consider.

Any help would be very welcome.

[shooter]

from 4 6L6 to 2 6V6

how confident are you?
what about pulling 2 of the L6's, double the speaker load, re-bias n see if you're going in the right direction

[Ed_Chambley]

I retubed my 66 with with 4, 6v6 JJ's before I sold it about 6 months ago.  I did not change the OT.  The OT was 2K/4 ohm.  This is 4k/8 ohms and 8K/16 ohms too, which was almost perfect for the 4 6v6.  Amp had just over 40 watts.  Has to change speaker wiring of course. 


I am certain this versatility is what helped sell the amp.  It sounded IDENTICAL to my Deluxe Reverb when using the extension cab, but did have more solid bass.


I also would run one of the JBL with 2 tubes which was 8K/16 and never caused a problem.  The JBL measure 8 ohms but state 16 ohs.  Common!  Did not even have to change the resistor on the Bias pot.  I chose this method so I could keep a Twin Accessible since I do play country when asked.  No better am for an outside gig than a Twin.


Just my 2$

[Auke Jolman]

Hi all,

Due to the reactions of Shooter and Ed Chambely I decided to take to not change the amp at this time. I will order 4 6V6's and take it from there.

[Ed_Chambley]

Auke, I hope you are not disturbed.  I have messed with Twins a lot.  If you really want to get sooner breakup, order some Warehouse 10's.  They cost about $50 EACH.  I have a single 10 cab with one and it is not an efficient speaker, therefore it breaks up much sooner than the JBL.


Also, disconnect your NFB.  This is usually good to make an amp breakup sooner.  You can also lower the 220uf filter caps to 80uf.  The amp you have is the 100 water, but the plate voltage is still within the JJ6v6S spec and they do last.


Having the stock OT is fine unless you are looking for OT saturation, but I found it nice because I got tube distortion only.  If you want you can run 2, 6v6s too, just use a 16 ohm speaker.  You can also reduce the first bypass cap to 4.7uf, hell I have even converted one to class A operation.


Would a Deluxe wattage and a single 10 that doesn't get loud do the trick.  It is sort of like a Deluxe with a Princeton speaker.

[Auke Jolman]

Hi Ed,

Don 't worry. I'm not disturbed. The amp was a gift from a friend and was in a very bad shape when I got it. It is just the amp is way to loud even with 2 6L6 pulled.

Your suggestions make sence. I think I'm going for 2 6V6 and rewire the speakers to serial.

Which speaker did you suggest exactly. I looked them up and there are a lot of 10 inch speakers.

[Ed_Chambley]

American 10