Electrodyne Audio 2501 Preamp User manual

2501 PREAMP™
Owner’s Manual

WARRANTY:
One Year Internal Parts And Lab r Warranty.
Your Warranty begins on the date of purchase. To activate your Warranty, please fill out and mail the Warranty Card to:
Pete’s Place Audio
P. . Box 4255
West Hills, CA 91304
U.S.A.
Also, your name may be placed on our mailing list for future updates and new product announcements (unless otherwise
requested).
Pete’s Place Audio reserves the right to make improvements and/or changes to this product at any time.
Y ur Warranty Is V id If:
1. This product has been opened by unauthorized personnel.
2. The product serial numbers have been removed or tampered.
3. The product has been damaged by misuse or abuse.
4. Modified and/or repaired by unauthorized personnel.
There Are N User Serviceable Parts Inside.
Pete’s Place Audio warrants that our hardware conforms substantially to the specifications contained in this manual. When used in
accordance these specifications, Pete’s Place Audio warrants for a period of one year from the date of purchase to the original
purchaser if purchased from Pete’s Place or its authorized dealers. In the case of a valid warranty claim, your sole and exclusive
remedy is Pete’s Place. Pete’s Place Audio entire liability under any theory of liability will be, at its option, to repair or replace the
product without charge or, if not possible, to refund the purchase price to you. This warranty is not transferable and applies only to the
original purchaser of this product.
For warranty service contact Pete’s Place Audio at 818-716-4153 to obtain a Return Merchandise Authorization (RMA) number. After
obtaining the RMA number, ship defective product to Pete’s Place Audio, P. . Box 4255, West Hills, CA 91304. Write the RMA number
on the outside of the shipping box. Be sure to include your name, address and phone number with a copy of original sales invoice and
detailed description of the problem. Pete’s Place Audio will not accept responsibility for loss or damage in shipping.
Pete’s Place, Pete’s Place Audio and ELECTR DYNE 2511 EQ are trademarks of Pete’s Place Audio and Electrodyne,
respectively. All other trademarks are the property of their respective owners.
Published by: Pete’s Place Audio
P. . Box 4255
West Hills, CA 91304
U.S.A.
Edition 1.0 2005
Copyright 2013 Pete’s Place Audio
All Rights Reserved.
LEGAL NOTICE
THIS WARRANTY IS IN LIEU F ALL THER WARRANTIES WHETHER RAL R WRITTEN, EXPRESSED R IMPLIED.
PETE’S PLACE AUDI MAKES N THER WARRANTY EITHER EXPRESSED R IMPLIED, INCLUDING, WITH UT
LIMITATI N, ANY IMPLIED WARRANTIES F MERCHANTABILITY, UNLESS F R A PARTICULAR PURP SE R
N NINFRINGEMENT. PURCHASERS S LE AND EXCLUSIVE REMEDY UNDER THIS WARRANTY SHALL BE REPAIR R
REPLACEMENT AS SPECIFIED HEREIN.
UNDER NO CIRCUMSTANCE WILL PETE’S PLACE AUDIO BE LIABLE FOR ANY DIRECT, INDIRECT, SPECIAL, INCREMENTAL
OR CONSEQUENTIAL DAMAGES RESULTING FROM ANY DEFECT IN THIS PRODUCT. THOSE DAMAGES INCLUDE BUT NOT
LIMITED TO LOST PROFITS, DAMAGE TO PROPERTY AND, TO THE EXTENT PERMITTED BY LAW, DAMAGE FOR PERSONAL
INJURY; EVEN IF PETE’S PLACE AUDIO HAS BEEN ADVISED OF THE POSSIBILITIES OF SUCH DAMAGES.

Intr ducti n
wner’s Manual | 3Electrodyne 2501 Preamp
™
Pete’s Place Audi
Intr duces...
The Electrodyne Audio 2501 Dual Mono Microphone Pre Amplifier was designed for both
Professionals and Home Recording Artists.
After the serious demand for the 501 Electrodynes' 500 Series Preamp, we found that not all
people in the recording industry want 500 Series and many are much more attracted to 19"
Rack Mounted gear.
Most companies will introduce 19'' rack mount products first, and if they have any success,
only then they will dive into the 500 Series Format. We have done just the opposite and
taken the 500 Series Electrodyne products to Dual Mono 19' rack mounted versions with all
the same tone and features,. Instead of sharing the limited resources of many 500
“lunchbox” power supplies, we paired them with their own powerful dedicated supply modules
ensuring top performance under any conditions. So, the qualities you fell in love with using
the Electrodyne 501 Preamp (and 511 EQ) are now even more accessible.
The 2501 is a 100% original Electrodyne design, not a clone or a copy. Electrodyne products
are still made here in the USA by Electrodyne Audio LLC, handcrafted the same as they were
in the 1960's and 1970's with the same proud workmanship and design that made them
collectable classics then, and today over 60 years later.
All current designs are built following actual original Electrodyne proprietary factory lab and engineering
notes. We have even gone to the trouble to have the designs reviewed and approved by original
Electrodyne engineering staff for accuracy and adherence to company design criteria.
So, we invite you to experience the rich tone that the 2501 delivers to any recording and the
limitless possibilities that will open creative doors to any project you work on.

4 | Electrodyne 2501 Preamp
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wner’s Manual
Features
All discrete transistor, transformer input/output design
Custom wound Input Transformers
Custom wound utput transformers
2db per step Gain Control for easy recall
Continuously variable utput Level control
Phase Reverse Switch
48v Phantom Switch
Active Class-A Fet DI
Dual Impedance Selector Switch
iginal design knobs and control levers (original manufacturer)
Rugged powder coated steel chassis
Heavy-gauge Anodized Aluminum Face Plate
All XLR I/
n/ ff Power Switch
Red LED Power Indicator
In line with our company policy of continuous development, the above features are subject to change without notice.

Specificati ns
wner’s Manual | 5Electrodyne 2501 Preamp
™
TECHNICAL DATA
Inputs:
Microphone: Custom wound original Electrodyne design multi-Impedance input transformer
DI: Active Fet impedance converter directly feeding the microphone input transformer.
utput: Custom wound original Electrodyne design large format multifilar transformers
Microphone transformer impedance: switchable 50 and 200 ohms
Fet DI impedance: Approximately 7 megohms
utput impedance: 600 ohms
Preamp section gain control: 12 positions, 2db per step
utput section gain control: continuously variable.
Maximum gain: 68db
Distortion: 0.007%typical.
Maximum output: +30dbu at less than 0.8%thd, +29.5dbu at 0.06%thd. (measured with +/-16v power
rails)
Frequency response: +/- 0.25db, <10hz to >70khz typical (no filters engaged).
Noise: -85db typ.I
In line with our company policy of continuous development, the above specifications are subject to change without notice.

6 | Electrodyne 2501 Preamp
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wner’s Manual
Functi ns
Fr nt Panel
1Signal Present Indicat r (green led)
2Input Gain C ntr l (stepped)
3Output Level C ntr l (c ntinu us)
4DI Switch (press t activate DI input)
51/4" Jack f r DI input
6Impedance Switch (switch ut=200 hms impedance, switch in=50 hms impedance)
7-20dB PAD f r Mic/DI Input (switch ut=pad ut, switch in=pad engaged)
8Phase Reverse Switch (switch ut=n rmal, switch in= ut f phase)
948v Phant m P wer with red led indicat r (press t activate)
10 P wer Switch with red led Indicat r

Functi ns (continued)
wner’s Manual | 7Electrodyne 2501 Preamp
™
Rear Panel
11 P wer Supply C nnect r
12 Balanced XLR Output, Channel B
13 Balanced XLR Input, Channel B
14 Balanced XLR Output, Channel A
15 Balanced XLR Input, Channel A
ALWAYS USE G D C MM N SENSE WHEN PERATING ANY ELECTR NIC EQUIPMENT.
IF Y U HAVE QUESTI NS, PLEASE C NTACT Y UR DEALER R THE MANUFACTURER BEF RE D ING
ANYTHING!!!!!

Dual gain stages:
Two stages of gain and a huge original Electrodyne design output transformer allow you to change the
character of each stage and ultimately your tone. Although the 2501 is a finely crafted studio
preamplifier the multi-stage design allows you to control the input and output gains separately,
simultaneously affecting the final drive level to the output transformer, to get tonal effects not possible
with single stage preamps. We carefully selected the original Electrodyne design output transformer to
respond very flat when presented with normal preamp levels, but provide warmth and desirable
harmonics in a controllable manner when driven hard.
“Z” switch: (Selectable Microphone Impedance)
The “Z” switch is a selectable impedance tap for the 2501 preamp microphone input transformer.
Impedance is one of many critical factors for determining how microphones will sound when
connected to a specific preamp. riginally, this Electrodyne preamp was designed for different
impedances by changing the input wiring. We have taken advantage of that and placed it as a front
panel “Z” switch.
Depending on each microphone components and internal design, changing the Z switch may
change the way the 2501 preamp and microphones interact, and as a result gain and frequency
response can change in wonderfully creative ways.
Imagine being able to press a button and get two or more different tones from one mic. From flat
response to various combinations of gentle peaks or roll-offs at high and low frequencies, or both -
you may be able to add extra sparkle, silkiness or control sibilance or harshness, add needed body
or warmth or remove unwanted boom or woolyness, all without touching an equalizer. Experiment
with the impedance switch settings with your favorite microphones to see what new tones are
possible.
Gain change when switching preamp impedance is normal and will be different for each mic type.
Some active, non-transformer output microphones may not change character or level with preamp
impedance change and this is also normal.

I
PETE’S PLACE AUDIO
P. . Box 4255
West Hills, CA 91304 USA (818) 716-
4153
www.petesplaceaudio.com