More dual secondary questions...

[1blueheron]

Since we seem to be on the topic of dual secondaries... I pulled out the Conn amp that I put away several months ago with a burned out 5y3gt.  I found another 5y3gt in it and powered up to take some readings on the PT.  This amp has dual secondaries.  One feeds a 5u4 and appears to be 300-0-300 (311-0-311VAC on 121V primary).  The other one feeds a 5Y3GT and I am seeing 384-0-384VAC (345-0-345 adjusted for 121V?)

Rectified output without load measured 400/400VDC on the 5U4 and 458/430VDC on the 5Y3GT.

Originally I was going to make a Reverberocket out of it, now I am wanting to build a Marshallesque 2204ish type amp.  It seems like this PT is a closer match for this purpose than the PT from the Wurlitzer which is kicking out 460VAC.

I am thinking I could actually build an all octal version ( V1=6F5, V2=6F5, V3=6SL7, V4=6SN7, V5=6L6, V6=6L6)  and a standard version with 3-12AX7A's and 2-EL34's on the same chassis and be able to switch between the two depending on the tone desired.
It might be kinda cool?  Has anyone tried this using a dual secondary PT or does it sound like a bad idea?   Chassis was originally set up for a quad of 12V6 and a pair of 6V6 as well as 4 noval sockets.  The chassis has a pretty similar layout to a marshall plexi.

About the time I got the voltage readings off the rectifier tubes a capacitor decided make like an Indian and let out some smoke signals.  Things got a little exciting. Sent wife went running. At first wisp of smoke I pulled the power but it had enough heat in the cap to blow the bottom out and spew oil.   Stunk pretty bad and was a mess to clean up but don't think any damage was done.  Will definitely need a re-cap.   

[PRR]

> the Conn amp

Which Conn amp?

[1blueheron]

Once again I left out a key piece of info didn't I.

OK, It is out of a Conn "Serenade".  Model #621-F.

It was exactly a year ago yesterday I picked it up and have had it stashed beside the bench.

Here was the original thread with pictures etc.. 


https://el34world.com/Forum/index.php?topic=23884.msg257462#msg257462

Project was abandoned when Sluckey encouraged me to get more experience with a simple amp first and so I went that direction rather than cutting this one up.  Now I am ready to take another stab at it and now I feel like the chassis layout and transformer would be better for a marshall than Ampeg.  Felt it would be better to start a new thread.

[PRR]

Schematic of related amp:
https://el34world.com/Forum/index.php?action=dlattach;topic=23884.0;attach=73660;image
That one runs two 6L6 and the flock of V6es. Is yours actually 6V6es in the main channel? (The 400V argues this amp was 6L6.)

[1blueheron]

Schematic of related amp:
https://el34world.com/Forum/index.php?action=dlattach;topic=23884.0;attach=73660;image
That one runs two 6L6 and the flock of V6es. Is yours actually 6V6es in the main channel? (The 400V argues this amp was 6L6.)

Chassis was originally set up for a quad of 12V6 and a pair of 6V6 6L6 as well as 4  5 noval sockets.  The chassis has a pretty similar layout to a marshall plexi.

See edit above...

I began verifying the schematic against the actual amp last night.  I got through the main section and only found 2 things different other than the single 15" speaker.

R15 = 2.7K
R22 = 15K

Hope to get through the rest of it tonite when I get off work.

[PRR]

> R15 = 2.7K  R22 = 15K

R15 is slightly lower minimum volume (for some reason the volume does not go to zero; you might decide it should).

R22 may be slightly better P-P balance, but depends on tubes (or tube-lot for a manufacturer), and balance is not a must-have in a guitar amplifier.

With the new tube line-up it does look like you could run four 6L6. Or six (or eight!) 6V6 (with appropriate heater connection). Sadly not four EL34.

[1blueheron]

Thanks PRR, 

I verified the rest of the schematic and it checks out.

So if I do one side all octal 6F5>6F5>6SL7>6SN7>2- 6L6GB fed off the red green pair and the other side 12AX7>12AX7>12AX7 > 4- 12V6 or 2-EL84 fed off the red pair, with only one half the amplifier being driven at any given time (channel selected with a foot switch and directing input from one side to the other),  would this be reasonable?

  I realize the OT for one side may be inadequate and require an additional OT be purchased unless the 6L6 OT could be shared somehow.