LaChapell Audio 583E, 583S Operating Manual

LACHAPELL AUDIO
583 Series Vacuum Tube Preamplifier Modules for
Microphones and Instruments (Model’s 583E & S).

Preliminary

Operating

Manual

PRODUCT SUMMARY: The LaChapell Audio 583 series modules feature single-ended vacuum tube

preamplifiers designed for use in the “500 series” format. The microphone input configuration is based on the
992EG and consists of an input transformer with a turns ratio of 1:10 and one ECC83/12AX7 vacuum tube.
The instrument input stage is transformer-less with the signal essentially going strait to the grid of the tube. The
output stage utilizes premium Burr-Brown and THAT Corporation line drivers along with an 80% nickel alloy
core transformer to generate a balanced line-level output signal. The model 583E features an ultra-clean
transformer-less three-band EQ section with fully sweeping frequency controls and cut/boost settings of +/­8dB... the EQ can run as an integrated EQ (serving the preamplifier) or separate as its own autonomous module

apart from the preamplifier.

Stated below are a few areas that you must take the time to read before you install and use your 583.
You as the owner/user are responsible for completely understanding how to operate this device
safely and properly.

UNPACKING: Inspect thoroughly. Although we take extreme care at final assembly and packing, things

can happen during transit. It is very important that you contact LaChapell Audio if there is anything broken
or damaged upon receipt of package. Shipping is always insured and we will do our absolute best to satisfy
any legitimate claim as long as it is made within 7 days of receipt. Included in every package should be: (1)
preliminary operating manual, (1) packet of mounting screws, (1) registration card. It is a good idea for you
to retain the packaging (box & foam case) in case there is a need to return the unit for service or repair at a
later date.

SERVICE/REPAIR: With the exception of tube replacement (see below) the user

should NOT attempt to service this unit in any way, due to the risk of electrical shock and the
presents of lethal voltages inside the 583 while powered. Only LaChapell Audio personnel are to
perform maintenance and service activities. The user should also take note that excessive ‘swapping’
of tubes will Introduce undue wear on the tube socket. It is therefore recommended that tube
replacement be performed only when necessary and by technically competent individuals.

Tube replacement: Turn power supply off and remove 583 from the chassis, wait five minutes to
allow the vacuum tube to cool before attempting to remove it. Using your fingers, apply a slight
circular/rotating motion as you pull it away from the socket. It is important to replace the tube
with the same type. When a replacement tube is installed double check that you’ve inserted the
correct tubes into the 583’s tube socket BEFORE powering up.

NOTE: The 583’s standard tube is the JJ ECC803. However, there are many different
ECC83/12AX7 variants that are virtually identical and can be used in either 583 module. These
include: ECC803, E83CC, CV4004, 6057, M8137, C492, 7025 and the 5751 (you will notice a slight
drop in gain when using the 5751).

WARNING: Warrantee may be void if tubes other than those listed above have been used
at any time.

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Controls:

INPUT: Drives more or less

current into the tube stage.

48V: Supplies 48 volts of DC

current for condenser micro-

OUTPUT: Drives more or less cur-

rent into the cleaner output stage.

HIGH: Frequency sweep range:

2.5Khz to 20Khz.

PAD: Reduces microphone input

signal by 20dB.

POLARITY: Reverses the polar-

ity of the output signal

INPUT: Activates Hi-Z or

Microphone input jacks.

All Toggle switches will illuminate red when

their associated function is active.

MID: Frequency sweep range:

325hz to 5Khz.

LOW: Frequency sweep range:

30hz to 400hz..

Each frequency band has

a cut/boost potential of

+ or - 8dB.

PRE + EQ: In this mode, the EQ section is internally

routed to serve the preamp’s output signal; effected
signal is sent out the left bay output jack.

Independent EQ: In this mode, the EQ section is available

as a completely independent module. The corresponding
rear right side connections are now active allowing you
to use the EQ on any external souse while the preamp
remains available on the left bay.

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