Duncan 84-50 Tube Owner's Manual - Page 10

Browse online or download pdf Owner's Manual for Amplifier Duncan 84-50 Tube. Duncan 84-50 Tube 12 pages. Tube guitar amplifier

Print Page

comes time for you to replace the whole set, if you get a quartet from us with the same

rating as the set you have, you won't have to re-bias the amp.

MAINTENANCE

Most maintenance procedures for your amp will involve the tubes. Refer any other

necessary work or adjustments to a qualified technician. THERE ARE NO USER

SERVICEABLE PARTS INSIDE. If your amp requires ser-vice, contact the

Seymour Duncan factory for the name of your nearest Authorized Service Center.

PLEASE NOTE: WE CANNOT ACCEPT UNITS SHIPPED TO THE FACTORY

WITHOUT A RETURN AUTHORIZATION NUMBER.

The 12AX7 preamp tubes should last up to 2-3 years, depending on the amount of

use. Symptoms, which indicate failing pre-amp tubes, include:

-Any intermittent noise (sputtering, ringing, etc.) that seems to come

and go as the amp warms up.

-Excessive white noise or hiss.

-Inability to get a clean sound, even a low volume levels.

The EL-84 tubes in the power section of the amp could last up to 2 years, depending on

volume levels and hours of use. High volume playing 3-4 hours a day, 5-6 days a week

could wear out a set of output tubes in a little as 6 months. Symptoms, which indicate

worn power tubes, include:

-Loss of power, punch; amp sounds "mushy" when pushed.

-Excessive hum.

If the outer plates of a tube begin to glow brightly, this tube has shorted. Turn off the

amp and replace the tubes, preferably with a matched set. It's OK in an emergency to

replace only one output tube, but all four output tubes should be replaced ASAP with a

matched set. These are tubes, which have been tested and matched according to their

power and performance characteristics (ex. RAM labs tubes, Groove Tubes, etc.). A

matched set of power tubes will significantly lower audible hum and increase power

output (possibly as much as 10-20 watts). This will offer more clarity on the clean

channel and a tighter low-end response for a punchier overdrive sound. Also, when

replacing the output tubes on your amp, it is good to have the amp's bias control

adjusted to achieve the optimum performance from a set of tubes. ALWAYS REFER

THE AMP TO A QUALIFIED TECHNICIAN FOR BIAS ADJUSTMENT.

Always store your amp in a dry area. Storage in damp areas will cause corrosion of

internal electrical contacts (switches, pots, jacks, etc.) and will in time degrade the

performance of the amp. Amps used in damp environments should be periodically

cleaned by a qualified technician. Symptoms which may indicate corrosion include:

-Potentiometer rotational noise (volume or tone controls sound "scratchy"

when turning). Use of a commercially available tuner spray will work in

most cases.

-Intermittent or noisy jacks.

-Intermittent tube noise that is affected by slightly wiggling the tube in its

socket.

To maintain the tolex covering on your amp, use "armor-all" type cleaner.