Lower Wattage Small Special

[wattsup]

I'm contemplating building a lower wattage Small Special. I know there are 20 and 40 watt Fender style transformers but I'd really like to get 30 watts. If that's even possible, what would be a good PT/OT combination? I've been looking at Magnetic Components. They have a wide variety and it looks like everybody I've read about using them likes them a lot. Thanks in advance.

[lord preset]

There's not a huge difference between 30 and 40 watts but you could look at one of the less beefy 40w Classictone sets (for ex. the Vibrolux PT/OT). The original Vibrolux was rated at 35 watts and has significantly less headroom and runs at lower plate voltages than most other 2-6l6GC Fenders. That could be a starting point assuming that lower headroom is what you are after.

[wattsup]

There's not a huge difference between 30 and 40 watts but you could look at one of the less beefy 40w Classictone sets (for ex. the Vibrolux PT/OT). The original Vibrolux was rated at 35 watts and has significantly less headroom and runs at lower plate voltages than most other 2-6l6GC Fenders. That could be a starting point assuming that lower headroom is what you are after.

Oh yeah that might be very good. I'm not really well versed in all the transformer stuff and am trying to understand what works and why. Could it make sense to take the vibroluxe PT and marry it with something like the 30 watt OT from the Trainwreck Express? Or would something like that even work? I've noticed some of the PT's have a rating listed in milliamps and all are different. I don't really know what the significance of that is and what it might affect.

[Synchu]

I am currently using Russian 6p3s-ev tubes in my small special. They are rated 19 watts. At 60% dissipation it is around 23-25 watts and if you want less headroom, you can always make the NFB loop switchable.
Niki

[lord preset]

Oh yeah that might be very good. I'm not really well versed in all the transformer stuff and am trying to understand what works and why. Could it make sense to take the vibroluxe PT and marry it with something like the 30 watt OT from the Trainwreck Express? Or would something like that even work? I've noticed some of the PT's have a rating listed in milliamps and all are different. I don't really know what the significance of that is and what it might affect.

I'm learning this as I go along but in general terms the PT is sized based on the number tubes you want to run and their current draw. OTs are selected on the basis of the expected wattage of the amp and the primary impedance needed for whatever set of power tubes you are using. There is an online calculator that is helpful in seeing how this works for PTs:

http://www.dreamtone.org/Calculate_Current_Form.htm

Selection of OTs seems to have a higher voodoo content. Many different OTs will "work" for a given output section design but will sound different in ways I wouldn't presume to understand. The TW Express has a primary impedance of 6.6k which is not typical for EL34 pairs but I can only assume Ken Fisher knew more about this than I do.. On my part I just pick OTs that are known to work in a given configuration and hope for the best.

[wattsup]

I'm learning this as I go along but in general terms the PT is sized based on the number tubes you want to run and their current draw. OTs are selected on the basis of the expected wattage of the amp and the primary impedance needed for whatever set of power tubes you are using. There is an online calculator that is helpful in seeing how this works for PTs:

http://www.dreamtone.org/Calculate_Current_Form.htm

Thanks that will definitely help!

[wattsup]

Ok so the milliamps is what the current draw on the PT primaries will be, depending on what type of power tubes you are using - is that correct?

[lord preset]

Ok so the milliamps is what the current draw on the PT primaries will be, depending on what type of power tubes you are using - is that correct?

Not exactly - PT primaries are AC input (120v, 240v, etc). Secondaries are the transformer outputs ( for ex 325-0-325v B+, 6.3v heater, etc). The Dreamtone calculator tells you the HV. (B+) current draw inclusive of both power and preamp tubes.

[wattsup]

Not exactly - PT primaries are AC input (120v, 240v, etc). Secondaries are the transformer outputs ( for ex 325-0-325v B+, 6.3v heater, etc). The Dreamtone calculator tells you the HV. (B+) current draw inclusive of both power and preamp tubes.

Uhm yeah. I can see that now - thanks! I'm learning

[groovtubin]

Not exactly - PT primaries are AC input (120v, 240v, etc). Secondaries are the transformer outputs ( for ex 325-0-325v B+, 6.3v heater, etc). The Dreamtone calculator tells you the HV. (B+) current draw inclusive of both power and preamp tubes.

Uhm yeah. I can see that now - thanks! I'm learning

A Allen amps princeton ( BEEFED UP heyboer) it`l even take EL-34`s, and a deluxe reverb OT would be nice! I get 450 B+ on that tranny with a full wave!

jim@omegaamps

[wattsup]

Uhm yeah. I can see that now - thanks! I'm learning

A Allen amps princeton ( BEEFED UP heyboer) it`l even take EL-34`s, and a deluxe reverb OT would be nice! I get 450 B+ on that tranny with a full wave.[/quote]

That sounds like it may be what I'm looking for. Definately going to take a look. Thanks!