Tweedle Dee build

[andresound]

Martin, I will try bigger resistor .
Marcus, my buddy is also building the same amp, so he wanted OD on a foot switch.... so good idea thanks

[andresound]

Cabinet Tolexing. My pet hate. But I am improving. Will load everything today, just waiting for a face plate

[andresound]

Calling her done. Thanks for all the help on the forum. Time to try her in a band situation. Fine tuning and tube rolling to come.

[martin manning]

Looking good! Let us know how it does with the band. Did you add any mods to the standard Tweedle Dee circuit? The beer is just for a size reference, I guess ;^)

[andresound]

Thanks Martin. Will let you know, and thanks for the help. Most appreciated . Yes the beer was for size reference

[andresound]

Looking good! Let us know how it does with the band. Did you add any mods to the standard Tweedle Dee circuit? The beer is just for a size reference, I guess ;^)

Martin, no mods yet. Guitarist used the amp last night and loved it. I briefly played it and thought it needed a bit more headroom. We do rehearse in a VERY “dead” room, so that might have contributed. However, I still need to adjust voltages, (bring the B+ up with a GZ34), and increase cathode resistor. I have noticed that when the cathode resistor is hot, it measures higher, which I assume in theory, would cause the tubes to run at a lower dissipation/wattage? Will revisit that.

[andresound]

Put the GZ34 back in and prefer the sound of the amp “hot”. I am not getting any red plating. I don't mind replacing tubes . I’m not a professional player, so the tubes should last a while. I know you guys don't like the bias calculator, but anyway.. this is what I got. My only problem is the heater voltage is 6.9v. Should I “pad” this with series resistors?

[pompeiisneaks]

I don't think slightly higher heater voltages will hurt, it may also shorten the life of the tube a bit, but again, not likely by much, the max heater voltage I remember seeing in some datasheets back when I researched this due to an EL34 being shorted from pin 3 to 2 was like 50V on 12A*7 types and 100V on many power tubes. This is the maximum before pretty much instant death to the filament of course, but anything over the expected rating will shorten the life I'm sure.

~Phil

[andresound]

Deleted

[martin manning]

It’s on the high side, but 6.9V is still within the +/-10% criteria specified in most data sheets so you are ok.

[andresound]

6.9V is still within the +/-10% criteria specified in most data sheets so you are ok.