What impedances do the bass heads operate?
Here is a list bass head impedances:

• SVT-CL/AV - 4 & 2 ohms
• SVT-2PRO - 4 & 2 ohms
• SVT-4PRO - 8, 4, & 2 ohms (stereo), 8 & 4 ohms (mono-bridged)
• SVT-3PRO - 8 & 4 ohms
• SVT-350H/AV - 8 & 4 ohms *V-4B - 8 & 4 ohms
• B-5R - 8, 4, & 2 ohms
• B-4R - 8, 4, & 2 ohms (stereo), 8 & 4 ohms (mono-bridged)
• B-2R - 8 & 4 ohms

Which cabinets are four ohm and which are eight ohm?
The following cabinets are four ohms enclosures:

• SVT-810E/AV (2 x 8 Ohms/4 Ohms)
• SVT-810HPC
• SVT-610HLF
• SVT-215E
• SVT-412HE
• SVT-410HLF
• SVT-18
• BXT-210M
• BXT-115HL4
• BXT-410HL4
• PR-410HLF
• BSE-410HLF

The following cabinets are eight ohms enclosures:

• SVT-810E/AV (2 x 8 Ohms/4 Ohms)
• SVT-410HE
• SVT-210HE
• SVT-15E
• BSE-410HS
• BSE-410H
• BSE-115

What is the impedance when I combine two eight ohm cabinets?
4 ohms

What is the impedance when I combine two four ohm cabinets?
2 ohms

Can I combine cabinets of different impedances?
It can be done, but it will cause a mismatch of levels. This is not recommended.

What is the impedance of an eight ohm cabinet combined with a four ohm cabinet?
2.7 ohms. This is not recommended

When I use my SVT-4PRO mono-bridged the volume is not what I expected for a 1600 watt amplifier. What's wrong?
Check your Speakon plug, it should be wired for +1 (positive) and +2 (negative) on the amp end. The cabinet end should be wired in the standard fashion, which is +1 (positive) and -1 (negative). Be sure to depress the stereo/mono-bridge button

What kind of tubes are in my SVT-4PRO, how many are there, and when should they be replaced?
The first tube in the pre-amp stage is a Groove Tube, as well as two other 12AX7A's found in the pre-amp section of the SVT-4PRO. Tube replacement may become necessary after one to three years, depending on enviroment, usage and care. Generally speaking, a tube does not need to be replaced unless it becomes noisy or microphonic.

What kind of tubes are in my SVT-3PRO, how many are there, and when should they be replaced?
The first tube in the pre-amp stage is a Groove Tube, as well as two other 12AX7A's found in the pre-amp section of the SVT-4PRO and one 12AU7 in the SVT-3PRO. Tube replacement may become necessary after one to three years, depending on enviroment, usage and care. Generally speaking, a tube does not need to be replaced unless it becomes noisy or microphonic. The SVT3-PRO contains 4 - 12AX7's and 1 - 12AU7 tubes.

Can I use an instrument cable (shielded) to connect my amp to my speakers?
No. Using instrument cable to hook up your speakers can cause intermittent power loss, cause your amp to oscillate and damage the amp and/or your speakers. Please use 18 gauge cable or heavier (16, 14, or 12).

Can I run my amp without any speaker cabinets connected to it?
Any Ampeg amplifier with a solid state output (SVT-4PRO, SVT-3PRO, SVT-350H, B-5,4, and 3R) can be used for recording purposes using only the line output to record and without speakers attached to the speaker jacks. The amp must have a speaker load if the amp has a tube output section (SVT-CL, SVT-2PRO, and V-4B), not doing so can result in extensive damage to the amplifier.

How can I obtain a manual for my amplifier?
You can download it from our website.

Where is the nearest Authorized Service Center to me?
Please click here for our Service Center Locator

What kind of speaker cable is required to mono bridge my SVT-IV PRO?
The prefered cable is 12 gauge with Speakon to Speakon connectors. Be sure to wire the Speakon on the "amp" end for +1 (positive) and +2 (negative). On the "cabinet" end wire the Speakon for +1 (positive) and -1 (negative). It is a good idea to label each end so there is no confusion on the gig.

How many cabinets can I use with the SVT-3PRO?
The SVT-3PRO will handle a minimum impedance of 4 ohms. This allows the bassist to use (2) eight ohm enclosures or (1) four ohm enclosure for maximum output (450 watts).

Which Ampeg amplifiers are bi-ampable?
The SVT-IVPRO and the B-4 both have built in crossovers and dual poweramps. This allows the user to operate the amp in bi-amp or mono bridge mode.

I did not receive a warranty card when I bought my amp. What do I do?
Not to worry! As of January 1, 1996 your sales receipt is your proof of warranty. The warranty is transferable by simply passing the original sales receipt or a copy to the next owner.

Who do I contact about becoming an Ampeg endorser artist?
Thank you for your interest in the Ampeg Endorsement Program. To be considered for endorsement, please provide the following:

• a copy of your current CD (and video if available)
• a current press kit including contact and management information
• a current tour schedule
• dates of your next Los Angeles, California performance
• a list of Ampeg products you currently use and product you desire for endorsement.

Send the noted items to the following address:
Yamaha Guitar Group, Inc.
Artist Relations Department/Ampeg
26580 Agoura Rd.
Calabasas, CA 91302 USA

How should I care for my Ampeg product's Tolex?
Ampeg products are covered with a durable, fabric-backed vinyl material. Clean with a dry, lint-free cloth. Never spray cleaning agents onto your Ampeg product. Avoid abrasive cleansers which would damage the finish. Keep out of continued direct sunlight to avoid vinyl seam curling or discoloration.