LunchBox WWA Instrument Amplifier
Now that covid is over, a lot of the users of the smaller wattage LunchBox Combo were looking for more power. They loved the format of the single volume control but maybe a bit more power.
The idea came to me in this design. Something you could use now and then use after you start to go out and play again. The requirements were as follows:
a) Volume Only, make the amp full range so it would work with any instrument.
b) A power supply that will work in any conditions world wide = WWA World Wide Amplifier.
c) Optional transformer coupled DI would give you connection to your DAW or House PA system
d) 9V Stomp box supply to you can power a small low current board.
e) Light weight with a cover.
f) All Tube design, 12-15W. Typically not found in amps of this size.
So for 12-15W that requires either a real hefty single ended design like a 6550/KT88 or a Push Pull amplifier. Well if I am going to do a PP amp then we have to do it my way, magnetically. So many companies struggle with what is called the phase inverter stage of the amplifier. You take the positive signal and create a single that is 180 degrees out of phase. They do this with tubes but never is it really 100% success as that is just not possible with tubes. I use a center tapped inductor. You feed the positive side on the input, ground the center tap and a 100% 180 degree out of phase signal comes out the other side. This gives you two things: (1) perfect signal on both sides (2) a super low resistance on the output tubes which gives you 20% more power! The output of the magnetic phase coupling (MPC) goes to a matched pair of 6AQ5 tubes. The input goes to a 12DW7 (12AX7 + 12AU7) with the input going to the AX driving the volume control and then the heftier AU side of the 12DW7 goes to the MPC. Warehouse 8” speaker would be in this design? Well it sounds incredible in both the Ceramic and Alnico versions.
So what's this WWA power supply. Well it's a switching power supply with both 6.3VDC for the filaments and 280V for the high voltage. When you turn this on, the 6.3W comes up to heat the tubes and about 20 seconds later the 280V slowly comes up to full voltage so the tubes don't get an immediate blast of voltage.
I would classify this amp as an instrument amp. It would work great with any instrument, Harp, Guitar, Fiddle anything with a pickup. It is full range and wide open, nothing specific to guitar. But it really is killer for guitar!
There are 2 versions of this amplifier. The standard 12W version comes with Mercury Magnetics output transformer and a standard set of high quality components. The turbo version comes with the SourSound outputs (about 20% larger than the MM) and Black Gate VK capacitors in the power supply (look em up on eBay $$$).
LunchBox WWA standard 12W version $1000.00, 15W Turbo option $1250.00.
Options: You can add the transformer coupled DI output for $250.00 and receive the cables for a TRS to XLR conversion.
The LunchBox comes standard with a high grade power cord and the CoverAmps fitted cover.
