Owner`s manual

SPEAKER POSTS - The speaker connection posts are on the back side panel and labeled on

the top panel. The RED is positive and WHITE (or black) is negative (ground). Be sure you

have speakers (or a 4 to 8 ohm load resistor) connected to these terminals before powering the

Stingray. Tube amps (unlike solid state) require a speaker if there is any chance there will be a

signal applied.

Watch out for reversing the positive and negative wires either at the amp or speakers (unless

you want to simulate record company executive's office hi-fi). The lows get lost, and the

image is very weird. If in doubt, try reversing one channel, the way with the most bass is

correct.

These terminals will accommodate most thicknesses of bare speaker wire and most U shaped

terminals or banana plugs. The only thing that they don't like is thin wire. You should avoid

thin wire for speaker cables in general. Use at least 18 guage (18AWG) or heavier. Bigger wire

has smaller AWG numbers. Be sure that the top bolts are tight, but avoid over-tightening that

might be difficult to undo or may damage the posts. In other words, firm as "strong finger

tight" but less than "big wrench tight".

These outputs are appropriate for speakers rated between 3 and 10 ohms which includes all

those 4 and 8 ohm speakers. For reference, the amp design and output transformers were

optimized for 5 ohms. You'll get a little less maximum power on either side of 5, but don't

forget that your speaker manufacturer is giving you a nominal impedance figure when he tells

you that you have "an 8 ohm speaker" which means your speaker's actual impedance swings

wildly vs. frequency all over the place. In real life, we have 5 ohms to be a good place to be for

most people. If you have some whacky speakers that hit strange extremes, then you might be a

good candidate to order some custom other-impedance output trannies from our in-house

magnetics department.

REPLACING A TUBE, INDICATOR LAMP or FUSE. You should read pages 9,10 and 16

to 18 for more details. You may need a small #1 Phillips screwdriver and the correct

replacement fuse, tube, or lamp. First be sure the unit is off and remove the IEC mains cable.

Let it sit for 20 minutes to be sure all power supply capacitors are discharged otherwise you

could still get a shock even though the unit is unplugged. Gently wiggle the tube around while

pulling it out of the socket. Avoid bending the printed circuit board. Before putting a new tube

in, look at it. Check to see that the pins are straight and that they line up to the socket. You

should be able to gently push the tube into the socket without excessive force. If it is the

indicator lamp that needs replacing, remove the bottom cover. Six screws near the sides hold it

in place - when these are removed, the cover should slide off. You will see what looks like a

fuse directly behind the black name panel. Gently pry the lamp out and replace it with another

lamp and not a fuse. Replace the cover before powering up the unit. The mains fuse is in the

IEC power connector sub-assembly. The fuse cover is a grey rectangle with a large slot and a

small slot. The small slot is to help remove the cover. A fingernail or small screwdriver in the

small slot is used to gently push or pry the tab towards the bulk of the grey cover. It should pop

open. The two B+ fuses are located under the bottom cover; see pg 8 under "ONE CHANNEL

DEAD" for details on replacing these. Refer to pg 20 for proper fuse types.