LaChapell Audio 583S MKII User manual

LACHAPELL AUDIO
Model 583s Vacuum Tube Preamplifier for Microphones
and Instruments
Preliminary
Operating
Manual

Stated below are a few areas that you must take the time to read before you install and use your 583s.
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 583s 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 583s from 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 583s’ standard tube is the ECC83. However, there are many different ECC83/12AX7
variants that are virtually identical and can be used in the 583s. 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.
PRODUCT SUMMARY: The Model 583s is a single-ended vacuum tube preamplifier de-
signed for use in the “500 series” format. Its’ 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 Cor-
poration line drivers with a transformer balanced output providing a typical output impedance
of 50 ohms.
1

SAFETY PRECAUTIONS:
Always provide adequate ventilation by allowing the top vents of your 500 series power supply chassis to
remain unobscured. Due to the vacuum tube and the internal secondary power supply, the 583s will get
warm, blocking or defeating any existing vent is not recommended.
Never position the power supply directly above other heat generating sources such as a power amplifier.
Always provide a source to ground (earth.) Never under any conditions should a power cord that has the
3rd prong for ground missing or defeated be used with the power supply.
Do not place the 583s in an area where there is a potential for fluids to fall, spill into or come in contact
with the 583s. If you notice fluids or moisture present inside the 583s DO NOT turn power on! Contact
LaChapell Audio for direction.
The 583s should only be used with power supply frames that have a >120ma rating per bay.
Controls:
INPUT GAIN: Adjusts gain within the input
stage of the preamplifier and has a typical range of
>30db via a fully variable 100kohm potentiometer.
OUTPUT GAIN: Throttles gain to the output
stage of the preamplifier and has a typical range of
40db via a fully variable 100kohm potentiometer.
48V: Supplies 48v of DC current to pins 2 & 3 of
the input jack for condenser microphones.
-20dB: Places a 20dB pad in front of the micro-
phone input transformer. This feature is defeated
when using the Hi-Z stage.
POLARITY: Reverses the polarity of pins 2 & 3
on the output jack.
INPUT: Allows the user to alternate between
microphone input and Hi-Z input.
All Toggle switches will illuminate red when their
associated function is active.2

2005~2007 LACHAPELL AUDIO
3144 N. G st. #125-354
Phone [phone]
www.lachapellaudio.com
Warranty: LaChapell Audio warrants that for a period of one year after the date of delivery, the Products
delivered hereunder shall perform in accordance with the written product specifications current as of the date of
shipment and under normal use shall be free from defects arising from selection of material or process of manufacture.
LaChapell Audio agrees to repair or replace at its principal business office in California or other authorized repair center,
without charge, all defective parts in the Products which are returned for inspection to said center within the warranty
period; provided such inspection discloses that the defects are as specified above, and provided further that the Products
has not been altered or repaired other than with authorization from LaChapell Audio and by its approved procedures,
not been subjected to misuse, improper maintenance, negligence or accident or otherwise had its serial number or any
part thereof altered, defaced or removed. All shipping and insurance costs for the Products repaired or replaced under
warranty are the responsibility of the party shipping the Products. All defective items replaced hereunder shall become
the property of LaChapell Audio
Internal Gain, microphone: >70dB
Internal Gain, Hi-Z: >50dB
Maximum output: +26dBu (1% THD+N)
Frequency Response: 12hz to >70khz (-3dB)
THD+N: <.25% (@50db gain, 0dBu out) typical
NOISE (EIN): Better than -120dB (rg=150ohm, 22hz to 20khz)
Input Impendence: 1.5kohm microphone, 40kohm Hi-Z
Tube Complement: (1) ECC83/12AX7
Output Impendence: 50ohm
Power Requirements: 220ma, +/- 14 volts (per API power supply)
Specifications:
Microphone
Input
-20dB Pad Control
Phantom (+48v)
Control
Direct Input (Unbalanced)
Input Gain Output Gain
Polarity Control
Polarity Tube Amp Balanced Output
Input
Select
-20dB
Pad
Phantom
3