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DS-4 — List: $599.00 Street: $449.00

Signal Chain

  • Ibanez 698MS
  • Dean Markley Vintage Bronze, Medium 13-56 (8 pack)
  • Dean Markley Refill Bag of 72 Medium Tortoise Picks
  • Dean Markley 3018 ProMag Grand Gold Humbucker Pickup
  • Dean Markley DS-4
  • Ibanez 2369B
  • Dean Markley Blue Steel Bass, 45-105
  • Millennia Music & Media Systems HV-37
  • Avid Digi 003
  • Toontrack EZ Drummer
  • Universal Audio UAD-2 Satellite Quad Core

100% All Natural Tone

Dean Markley's Ultrasound DS4 delivers 50 Watts of unmatched acoustic tone, in a lightweight combo package. The DS4 is a 50 watt, 2 x 8" acoustic guitar combo amp. Two instrument channels feature phantom-powered microphone inputs along with volume and active EQ for each channel. Other features include a studio quality DI, Effects Loop, and an additional Aux. Input for Tape/CD, drum machine, etc. To further enhance the DS4, the onboard 24-bit digital effects processor produces studio quality reverbs, delays, and chorus effects, which can be routed to either or both channels. CHANNEL-1 is designed for both MIC level (XLR) or Instrument level (1/4") signals. The 1/4" TRS (Tip/Ring/Sleeve) input jack is suited for equipment such as high impedance microphones, keyboards, and drum machines. It accepts both balanced and unbalanced inputs. (Channel-1 is designed as a generic "flat response" channel that is suitable for any acoustic instrument level or microphone signal.) CHANNEL-2 is designed primarily for acoustic guitar and is equipped with an 18dB cut NOTCH FILTER that is used to control resonant feedback and a mid-cut SHAPE CIRCUIT to eliminate mid range モquackヤ from your guitar or pickup.


INPUT-1: This combo input is designed for both MIC level (XLR) or Instrument level (¼”) signals. (The XLR input provides phantom power)
VOLUME: Controls the overall volume level of CHANNEL-1.
BASS: Adjusts the amount of cut or boost in the low frequency range.
TREBLE: Adjusts the amount of cut or boost in the high frequency range.
Note: When CHANNEL-1 is not in use, be sure to turn all controls to the minimum level to avoid any unwanted noise being passed through the amplifier.


INPUT-2: Combo Input designed for both MIC level (XLR) and Instrument level (¼”) signals. (The XLR input provides phantom power)
VOLUME: Controls the overall volume of CHANNEL-2.
BASS: Adjusts the amount of cut or boost in the low frequency range.
TREBLE: Adjusts the amount of cut or boost in the high frequency range.
Notch Filter HZ: Sets the frequency of the 18db cut NOTCH FILTER that is used to control resonant feedback.
Notch Filter: ON/OFF - Enables or disables the notch filter control.
Shape: ON/OFF This toggle switch enables or disables the SHAPE control. The shape control is a mid dip control. In the on position the mid frequencies will be cut and the high and low frequencies will be boosted.


Effects Assign: This 3 way toggle switch allows the digital effects to be routed to CH-1, CH-2, or if in the middle position will supply effect for both channels.
Effects LEVEL: Controls the amount of digital effect mixed in to the guitar signal from 0% to 50%.
Effects MODE: This is a rotary encoder, which selects 1 of 16 different digital effects. See Digital Effects Program List.
MASTER VOLUME: Adjusts the overall loudness of the amplifier.
Pilot Light/Limit Indicator : When GREEN, this LED indicates that the power is turned on. If the power amplifier reaches full power output, the on board Limiter will be enabled and this LED will turn RED. The Limiter allows the amplifier to be played at full power without unwanted distortion.


EFX F.S. (FOOTSWITCH): This jack is for connection to a shorting footswitch. When the switch is closed the on board digital EFX will be bypassed.
EFX SEND: This jack provides an unbalanced output from the CHANNEL-2 preamp, it does not include effects or tone control signal.
EFX RETURN: This jack provides a signal pre-eq. It automatically disconnects the CHANNEL-2 preamp when used.
LINE OUT: This jack provides an unbalanced out put from the preamp that is post eq and post efx. This send can be used to feed a signal to a recording or sound reinforcement mixer. Additionally this output can be used to drive a slave amp such as the ULTRASOUND AG-50E.
DIRECT OUT: Balanced output signal, post eq and post efx, used to feed recording or sound reinforcement equipment.
TAPE/CD: Unbalanced phono (RCA) input jacks. This is an auxiliary input designed for use with a drum machine, tape player, CD player, etc. and can be used for playing prerecorded music.
TAPE/CD LEVEL: This “inset” control adjusts the volume level of the TAPE/CD input. This control can be adjusted with a small screwdriver. This signal is pre MASTER control which means that the MASTER volume setting will affect the loudness of the TAPE/CD input signal.

Starting with the Ultimate Speaker Demo, an ever-increasing number of the GearTunes audio  clips are being tracked using the Radial JCR Reamp. The Reamp was invented by my good friend and colleague John Cuniberti who engineered/co-produced many of Joe Satriani's most infamous recordings.

For GearTunes, reamping allows me to record a track where the guitar "hears" the amp in the room, but initially only the guitar or guitar and effects signal is recorded. This allows me to spend additional time perfecting amp tones and mic placement once I have the performance I'm looking for. One of the byproducts of this process is the creation of GearTunes DI Clips which enable you to play select guitars and effects through your amp by using your mobile device or computer as a reamp device.

For GearTunes DI Clips - and Gear Tune DI Clips ONLY (always found under the DI clips tab for gear that has one), you can play our guitar and effects through your amp. Simply use an unbalanced cable that terminates with an 1/8th inch jack on one end and a 1/4 inch jack on the other. Connect the 1/8th jack to the output of your mobile device or computer and the 1/4 inch jack into the front of your amp. Start off with your amp volume at zero and your mobile device (or computer) volume all the way up to ensure you hit the front end of the amp with enough signal, and then gradually increase the volume of the clean channel on your amp until you reach a level that is not capable of causing damage to your ears or equipment. GearTunes accepts no liability for the use, abuse or misuse of these clips, and playing them into your amp is done exclusively at your own risk.

I am tremendously excited about being able to share GearTunes DI Clips with you as you journey on your quest to find right gear for the music you play! Cheers ~ Doug:)

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