PLEX - Audio Amplifier Friedman - Free user manual and instructions
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| Product type | Electric guitar amplifier head, all-tube, 50 W |
| Brand | Friedman |
| Model | PLEX HEAD |
| Power | 50 watts RMS |
| Technology | All-tube |
| Power tubes | 2 x EL34 |
| Preamp tubes | 3 x 12AX7 |
| Channels | 2 distinct channels (Lead and Normal), each with volume control |
| Channel bridging | Internal channel bridging (Lead/Normal blend) |
| Master volume | Post-phase master volume |
| Tone controls | Bass, Middle, Treble, Presence (global) |
| Bright switch | 3-position Bright switch per channel |
| Inputs | Hi and Low instrument inputs |
| Speaker outputs | 4, 8 and 16 ohms |
| Transformers | Custom-made, manufactured in the USA |
| Assembly | Assembled in the USA |
| Inspired by | Dave Friedman's 1968 JMP Super Lead Plexi |
| Care and cleaning | Clean with a slightly damp cloth; do not use abrasive products; avoid moisture |
| Safety | Do not expose to water or moisture; unplug during prolonged inactivity; call a qualified technician for any repairs |
| Spare parts and repairability | Replacement tubes (EL34, 12AX7) available; tube replacement and biasing by a professional |
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USER MANUAL PLEX Friedman
FRIEDMAN
AMPLIFICATION
PLEX
INSTRUCTON MANUAL
Congratulations on purchasing this incredible new guitar amplifier designed by one of the most well-known amp modders and designers in the LA Music scene for the past 20 years
Dave Friedman's personal 1968 JMP Super Lead "Plexi" kicked off his lifelong quest for tone and inspired the entire Friedman Amplification product line. Friedman has earned the reputation of a master amp builder and capturing the magic of this unique amplifier has been his unrelenting passion-project for years. The Friedman PLEX head is the realization of that dream.
The PLEX is a “verbatim sonic-twin” of Dave’s all-time favorite amplifier - that special ‘68 JMP. Sparing no expense in time and effort, Dave took great care in defining and utilizing the best modern construction techniques, sourcing the exact parts and finding the perfect tubes to reproduce this amp’s character. The Friedman PLEX is, in Dave’s own words “my favorite.”
The Vintage Collection
The PLEX is the first model in the Friedman Vintage Collection – a series of unique amp designs based on the classic amplifiers that influenced and shaped Dave's Friedman tonal signature. The Vintage Collection captures the sonic nostalgia and authenticity of yesteryear, while infusing decades of Dave's knowledge into each design.
Authentic Plexi Tone
The PLEX is a 50-watt, 2-channel, EL34-driven design that meticulously captures the genuine Plexi tone and feel of Dave's revered 1968 JMP Super Lead. Distinct Lead and Normal channels, each equipped with their own Volume controls, replicate the non-master volume performance of its predecessor perfectly. The harder you push these channels, the more the amp responds with increased saturation, harmonic richness and sustained brilliance.
Internal Channel Jumpering
The Friedman PLEX features internal channel jumpering, replicating the external blending technique used with vintage Plexi amplifiers. This feature lets you easily blend the Lead and Normal channels to perfection with the turn of a control knob. It's a seamless and convenient sound-shaping method that pays homage to the amp's history.
Friedman Post-Phase Master Volume Control A modern twist on the PLEX's vintage heritage is Dave Friedman's master volume control. As the Normal and Lead channels' gain increases, so does their volume. Dave's innovative approach lets you bring the amp back to manageable levels, without sacrificing the tone or dynamic feel, he worked so hard to replicate. This unique post-phase master volume design ensured that, whether you're unleashing the PLEX's full power, or dialing it down for quieter settings, the amp's inherent character and tonal richness remains intact.
Tonal Flexibility
Completing the PLEX's sonic palette is a vintage-style tone stack comprising of Presence, Bass, Middle and Treble controls. This tone stack and the inclusion of Hi and Low instrument inputs allows you to sculpt a wide range of sounds and gain levels. The 3-position Bright switch further enhances the PLEX's flexibility, fine-tuning the amp's top end to different guitars, pedals, and pickups.
True to the Friedman standard, the PLEX boasts a bullet-proof design, unwavering build integrity, and top-tier components, guaranteeing that it will be a lifelong companion on your musical journey.
- 50-Watt All-Tube Head
- Inspired by Dave Friedman's favorite '68 JMP Super Lead Plexi
- Channel 1 Volume (Lead spec channel)
- Channel 2 Volume (Normal spec channel)
- Internal Channel Jumpering
● Post-Phase Master Volume Control
● 3-Way Bright Switch Per Channel
● Bass, Middle, Treble, And Global Presence - 2 X EL34 Power Tubes
• 3 X 12AX7 Preamp Tubes
• 4, 8, And 16-Ohm Impedance Jacks - Custom, USA-Made Transformers
- Assembled in the USA
We know you will love your new PLEX. If you have any questions or need help don't hesitate to email us at friedmanamps@gmail.com.
INSTRUCTIONS
Please keep this instruction manual for future reference and for the duration of owning this Friedman Amplifier. Please carefully read and understand the instructions inside this user's manual before attempting to operate your new amp. This instruction manual includes essential safety information regarding the use and maintenance of the amplifier. Take special care to heed all warning symbols and signs inside this manual and those printed on the amplifier itself.

WARNING!
TO PREVENT FIRE OR SHOCK HAZARD, DO NOT EXPOSE THE AMPLIFIER TO WATER OR MOISTURE. DO NOT OPERATE NEAR ANY WATER SOURCE

WHAT'S THE MEANING OF THIS?
The lightning flash with an arrow triangular symbol is intended to alert the user to the presence of non-insulated “dangerous voltage” within the products enclosure, and may be of sufficient magnitude to constitute a risk of electric shock

WHAT'S THE MEANING OF THIS?
The exclamation point triangular symbol is intended to alert the user to the presence of important operating and maintenance (servicing) instructions in the user manual accompanying this amplifier!
- Read Instructions – All the safety and operating instructions should be read before this product is operated.
- Retain Instructions – The safety and operating instructions should be retained for future reference.
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Heed Warnings – All warnings on the amplifier and in the operating instructions should be adhered to.
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Follow Instructions – All operating and use instructions should be followed.
- Water and Moisture – The amplifier should not be used near water – for example, a bathtub, washbowl, kitchen sink, laundry tub, wet basement, or near a swimming pool, and the like.
- Heat – Amplifier should be situated away from heat sources such as radiators, heat registers, stoves, or other amplifier (including amplifiers) that produce heat.
- Power Sources – This product should be operated only from the type of power source indicated on the rating label.
If you are not sure of the type of power supply to your home, consult your product dealer or local power company.
- Grounding or Polarization
- This product may be equipped with a polarized alternation-current line plug (a plug having one blade wider than the other). This plug will fit into the power outlet only one way. This is a safety feature. If you are unable to insert the plug fully into the outlet, try reversing the plug. If the plug should still fail to fit, contact your electrician to replace your obsolete outlet. Do not defeat the safety purpose of the polarized plug.
- Power-Cord Protection
- Power-supply cords should be routed so that they are not likely to be walked on or pinched by items placed upon or against them, paying particular attention to the cord in correspondence of plugs, convenience receptacles, and the point where they exit from the amplifier.
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Cleaning – The amplifier should be cleaned only as recommended by the manufacturer. Clean by wiping with a cloth slightly damp with water. Avoid getting water inside the amplifier.
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Non-use Periods – The power cord of the amplifier should be unplugged from the outlet when left unused for a long period of time.
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Object and Liquid Entry
- Care should be taken so that objects do not fall and liquids are not spilled into the enclosure through openings.
- Damage Requiring Service
– The amplifier should be serviced by qualified service personnel when:
A. The power-supply cord or the plug has been damaged; or
B. Objects have fallen, or liquid has been spilled into the amplifier; or
C. The amplifier has been exposed to rain; or
D. The amplifier does not appear to operate normally or exhibits a marked change in performance; or
E. The amplifier has been dropped, or the enclosure damaged.
F. The amplifier needs tube replacement or biasing
- Servicing – The user should not attempt any service to the amplifier beyond that described in the operating instructions.
All other servicing should be referred to qualified service personnel.
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Ventilation – Slots and openings in the cabinet are provided for ventilation and to ensure reliable operation of the product and to protect it from overheating, and these openings must not be blocked or covered.
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Attachments – do not use attachments not recommended by the product manufacturer as they may cause hazards.
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Accessories – Do not place this product on an unstable cart, stand, tripod, bracket, or table. The product may fall, causing serious injury to a child or adult, and serious damage to the product. Use only with a cart, stand, tripod, bracket, or table recommended by the manufacturer, or sold with the product.
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Lightning – For added protection for this product before a lightning storm, or when it is left unattended and unused for long periods of time, unplug it from the wall outlet. This will prevent damage to the product due to lightning and power line surges.
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Replacement Parts – When replacement parts are required, be sure the service technician has used replacement parts specified by the manufacturer or have the same characteristics as the original part. Unauthorized substitutions may result in fire, electric shock, or other hazards.
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Safety Check – Upon completion of any service or repairs to this product, ask the service
technician to perform safety checks to determine that the product is in proper operating condition.
- FUSES – Always use the correct rating and type of fuse as indicated on the rear panel. Note the proper rating fuse is determined by the AC line voltage in the country this unit is being operated.
FRONT PANEL

POWER SWITCH: Off is center, up is High Voltage, down is Low Voltage (variac mode) Turn ON in position of choice for about one minute before playing for maximum tube life.
STANDBY SWITCH: Leave the amp in standby mode while amp warms up. Switch to on mode to play.
M.V.C. CONTROL: This is a unique post phase inverter master volume. Down is lower overall volume but why would you want to do that!!
PRESENCE CONTROL: add and takes away high frequency content. Will not do much with low M.V.C settings.
BASS CONTROL: This adds or takes away bass or bottom end.
MIDDLE CONTROL: Adds or takes away midrange. Start at 6 or 10, lower settings will scoop the mids, higher levels will allow your audience to actually hear the guitar in the mix.
TREBLE CONTROL: This adds or takes away treble. Start at 8 and adjust to taste.
VOLUME 1: This is the volume for the Lead channel (treble channel). Louder means more gain I say start at 10
VOLUME 2: This is the volume for the normal channel (bass channel). Can be used to blend with the other channel or with a Strat alone for a fatter cleaner tone. Start at 0
BRIGHT SWITCHES: Standard style British amp setup for blending would be Volume 2 bright to the center and volume 1 bright to the right. We have given you 2 bright switches to come up with your favorite sound. There is no really wrong setting if you like it..
INPUT H/ L: Just like it says. These are Input Jacks. Pick hi or low sensitivity your choice. This is where you insert your guitar cable if you want to hear the darn thing.
BACK PANEL




FRIEDMAN AMPLIFICATION
LOS ANGELES, CALIFORNIA
WARNING: DO NOT OPEN OR ATTEMPT TO SERVICE THE AMPLIFIER BY YOURSELF. REFER ALL SERVICING TO AN AUTHORIZED DEALER. REFER TO INSTRUCTION MANUAL FOR ADDITIONAL WARNINGS AND PRECAUTIONS.
CAUTION: TO REDUCE THE RISK OF FIRE OR ELECTRICAL SHOCK, DO NOT EXPOSE THIS AMPLIFIER TO RAIN OR MOISTURE.
WARNING: TO REDUCE THE RISK OF ELECTRICAL SHOCK, DO NOT REMOVE COVER. REFER TO QUALIFIED PERSONNEL. AVIS: RISQUE DE CHOC ELECTRIQUE / NE PAS OUVRIR.
CAUTION: REPLACE ONLY WITH SAME TYPE FUSE.
UTILISER UN FUSIBLE DE RECHANGE DE MEME TYPE.
□ 100V - T3AL 250V
□120V-T3AL 250V
□ 240V - 11.5A 250V 50/60 HZ 175 WATTS

MUST BE EARTHED
4 OHM SPEAKER OUT JACKS (2): Plug in ONE 4 OHM cabinet or TWO 8 OHM cabs here.
8 OHM SPEAKER OUT JACKS (2): Plug in ONE 8-ohm cab or TWO 16-ohm cabs here.
16 OHM SPEAKER OUT JACK: Plug in ONE 16-ohm speaker cab here.
MAIN FUSE: This fuse is in the compartment found below the AC receptacle. Replace with the appropriate fuse as marked on the back panel. If this fuse blows, it is probably the result of a bad tube. Constant blowing of this fuse (even when using new tubes) is an indication that something could be seriously wrong with your amp. STOP and call us so we may help you diagnose.
MAINS INPUT: Plug the supplied IEC power cord here.
FRIEDMAN LIMITED LIFETIME WARRANTY
Thank you for choosing Friedman. Friedman manufactures some of the world's most reliable hand-wired, all-tube amplifiers and speaker cabinets. Friedman takes great pride in an extremely thorough testing procedure which is implemented on each product prior to shipment. In the unlikely event that you have a problem with your amplifier, please refer to warranty below. Friedman stands behind our products like no other and we're here to help you!
AMPLIFIERS: Friedman offers a limited lifetime warranty to the original purchaser that a Friedman amplifier will be free from defects in material and workmanship. A dated sales receipt will establish coverage under this warranty, PLEASE KEEP YOUR PROOF OF PURCHASE TO USE YOUR WARRANTY. This warranty does not cover service or parts to repair damage caused by accident, neglect, abuse, normal & wear, disaster, misuse, abuse, over-powering, negligence, inadequate packing or shipping procedures and service, repair or any modifications to the product which have not been authorized or approved by Friedman in writing. ANY MODIFICATION TO THE AMPLIFIER WILL VOID YOUR WARRANTY. If this product is defective in materials or workmanship as warranted above, your sole remedy shall be repair or replacement by Friedman as provided below.
CAUTION: Do NOT attempt to repair, modify or service your amplifier by yourself!!! Please read the instruction manual for all safety notifications, warnings and instructions. Friedman, like all tube amplifiers, have extremely high voltages that can cause serious injury or death. Do not remove the chassis from the amplifier. All repair and service work must be performed by Friedman or an authorized service center of Friedman.
ANY UNAUTHORIZED REPAIRS WILL VOID YOUR WARRANTY.
TUBES: Friedman warrants the original purchaser that the specific tubes used in Friedman will be free from defects in material and workmanship for a period of 90 days from the original date of purchase. A dated sales receipt will establish coverage under this warranty. This tube warranty will automatically terminate 90 days after the original retail sales date. This tube warranty is in lieu of all other expressed warranties. If tubes fail within the 90-day warranty period, your sole remedy shall be replacement of tubes as provided below.
RETURN PROCEDURES: In the unlikely event that a defect occurs please email us at friedmanamps@gmail.com. In most cases we can help you diagnose the problem. If a product must be sent to us, please follow the procedure outlined below.
- Defective products must be shipped, together with proof of purchase, freight pre-paid and insured to the Authorized Friedman Service Center or directly to Friedman.
- If a product must be returned to Friedman for warranty replacement/repair, a Return Authorization Number must be obtained from our Customer Service Department prior to shipping the product.
- Please contact Friedman Customer Service Department for the Authorized Friedman Service Center nearest you.
- Products must be shipped in their original packaging or its equivalent; in any case, the risk of loss or damage in transit is to be borne by the purchaser.
- The Return Authorization Number must appear in large print directly below the shipping address.
• Always include a brief description of the
defect, along with your correct return address and telephone number.
- When calling to inquire about a returned product, always refer to the Return Authorization Number.
If Friedman determines that the unit was defective in materials or workmanship at any time during the warranty period, Friedman has the option of repairing or replacing the product at no additional charge, except as set forth below.
- All replaced parts become a property of Friedman. Products replaced or repaired under this warranty will be returned via ground shipping within the United States or Canada - freight prepaid.
- Friedman is not responsible for costs associated with expedited shipping, either to Friedman or the return of the product to the customer.
All warranty repairs outside the United States and Canada must be directed to the dealer or distributor from which you purchased the product.
INCIDENTAL OR CONSEQUENTIAL DAMAGE: In no event will Friedman be liable for any incidental or consequential damages arising out of the use or inability to use of any Friedman product, even if a Friedman dealer has been advised of the possibility of such damages, or any other claim by any other party. Some states do not allow the exclusion or limitation of consequential damages, so the above limitation and exclusion may not apply to you. This warranty gives you specific legal rights and you may also have other rights which may vary from state to state.
FOR YOUR PROTECTION: Please complete and send in the completed warranty registration card to: Friedman Amplification, care of Boutique Amps Distribution, 5300 Harbor Street, Commerce, CA 90040. Please send within (10) ten days of the date of purchase so that we may contact you directly in the event a safety notification issued in accordance with the 1972 Consumer Product Safety Act.
CUSTOMER SUPPORT: Our dedicated and friendly staff is ready to help you with any warranty or product questions you may have. Please email us at friedmanamps@gmail.com.
Thank you again for choosing Friedman and we look forward to a long relationship!

AMPLIFICATION
www.FriedmanAmplification.com