Trinity OSD Kit


Many people have asked about Trinity Amps developing an Overdrive type kit so we have decided to re-design our OSD  into a builder friendly package that will meet out stringent support requirements.

The Trinity Amps OSD is modelled after the 100W Dumble ODS #124 with just a few less frills. It boasts a nominal 22W / 6V6 or 33W / 6L6 output stage in a compact chassis format of only 17 in W X 2-1/2” in H X 8-1/2 in D . It has two channels – Clean and Overdrive. The amp uses using 6V6 output tubes in fixed bias mode with an option to run 6L6 power tubes. Since most on-stage set-ups are miked, 100 watts power is almost never required and 22 watts is both sufficient and surprisingly loud even for medium gigs, especially in this design. This lower wattage helps keep volume levels manageable and makes it very useful in a studio.

The preamp has three 12AX7 tubes which are used for the Clean channel, Overdrive channel and the Phase Inverter. On the back of the amp there is a control to configure Overdrive channel Trim. The Overdrive channel and Pre-Amp Boost (PAB) are activated with a footswitch connected to the back of the amp. There is also a passive effects loop, like in the originals. This is very effective if, for example, you want to inject some reverb. We have used a Holy Grail Reverb pedal here and it works very well. There is an option for a buffered effects loop.

The “spanky” clean preamp has a percussive nature is extremely inspirational. This preamp stays nice and clean and allows you to crank the power amp to achieve a highly percussive tone that taps into the compression and sustain of the power amp tubes.

The magic of the OSD comes from the Overdrive channel sound. The Overdrive channel provides a very smooth, sweet sustaining distorted tone. Activating the Overdrive circuit adds two additional gain stages and the result is an Overdrive that ranges from clean and harmonically rich to smooth and thick with ample saturation.

The amp has one input going straight to the first tube stage. No FET input.
The first tube triode is followed by a passive tone stack with controls for Treble, Middle, Bass and Volume. There are two mini toggle switches on the front panel for Mid Boost and Rock/Jazz and the Volume control can be pulled out for a brighter sound.
The Treble, Mid, Bass tone stack is followed by another triode stage. The resulting signal is either fed straight into the power amplifier (Clean channel) or into the Overdrive channel circuitry.
The output section uses a standard long tail pair phase inverter utilizing negative feedback. Since there is negative feedback, the phase inverter section of the amp also features aPresence control. This will add sparkle and clarity to your tone. Prior to the phase inverter there is a Master Volume control which is very effective at setting the overall volume of the amp.
The power supply uses a diode full wave rectifier and is somewhat unique in that they use a lot of filtering in the power supply (100uf / 50uf X4) . The large filter capacitors help keep the tone tight and focused because you don’t want loose sounding bass especially in Overdrive mode!
On the back of the amp, there are two speaker output jacks, a 4-8-16 ohms speaker impedance selector and fuses for Mains and High Voltage.

For the Overdrive channel to attain its very smooth, sweet sustaining distorted tone, it is carefully tuned in terms of gain and frequency response.

The Overdrive channel and Pre-Amp Boost (PAB) are activated with a two-button footswitch. Both the channel switching and PAB switching is done by two relays inside the amp. The PAB accentuates midrange frequencies and attenuates low frequencies, making it great for cutting through during a solo. Engaged, you will also notice an increase in gain and distortion characteristics. This is useful for pushing the power section, lead boost and getting a bit of extra dirt from the amp.

The Overdrive channel consists of two cascaded triodes being fed from the clean channel signal. Gain is attenuated before and after each of the two triode stages in the Overdrive channel. This limiting of gain keeps the amp smooth and prevents over the top harsh distortion tones. The Overdrive channel features two front panel controls – Ratio which serves a sort of volume control for the overdrive channel and Level adjusts the amount of gain, and in turn distortion in the overdrive mode. On the back of the amp there is a Trim control that controls the amount of signal sent into the first stage of the Overdrive circuit.

The OSD design is well thought out from a builders perspective and uses a single eyelet board and a single relay PCB. Parts selection, lead dress, voltages and tube selection are critical in getting a good sounding amp.


16Jul17: Design concept complete – single main Board concept; Layout & Schematic complete; BOM with parts selected ; blank Chassis arrived; Heyboer Transformer set arrived.

14Aug17: Prototype Front panels received; selected parts received

17Aug17: Eyelet board built; Transformers located  using headphones to  find quietest position.

Next Step: Design chassis layout and punch chassis. 

Plan is for 15-17Sep to Build and Reveal the prototype!!

Click +Inquire below to RSVP or to get more information.

Coming Fall 2017


Orange Drop 716 series 150 caps; 1 Watt CARBON FILM resistors; 1% Vishay Metal film where required for low noise and precision, CLIFF and SWITCHCRAFT jacks; ALPHA pots; JJ filter caps; BELTON Micalex tube sockets, Tube retainers & shields; 1/8″ t hick GP03 Turret Board with KEYSTONE Eyelets; CARLING switches; 10A impedance switch; GENERAL CABLE 22 gauge solid core hook-up wire and pre-twisted heater wire; BELDEN Co-Ax cable; All Mounting hardware, spacers and nuts; Front Black and Rear faceplates with White reverse engraved lettering; Pre-Cut 0.09″ Aircraft Aluminum Chassis with tapped holes for tube mounting screws; Detailed 90+ page Builders with large 11″ X 17″ sized schematic and colour layout; Real SUPPORT
Kit Includes Custom made Heyboer Transformer set (OT, PT) built to critical specifications.

Tube Recommendation: NOS RCA 12AX7 for V1 (Clean channel); Mullard reissue 12AX7 for V2 (Overdrive channel); Tung Sol 12AX7 for Phase Invertor V3; Tung Sol 6V6 power tubes.

We are targeting the Trinity OSD kit at an introductory price of $650 – $700 USD including a two-button, footswitch with indicators.
Shipping will be $60-$40 USD within North America
Price does not include Tubes or Cabinet.

Custom Head Cabinet $260 USD
Custom 112 Combo Cabinet $350 USD
Active FET Buffered Effects Loop with Preamp Out $80 USD

Click +Inquire below to RSVP or to get more information.


  • Channels: 1
  • Controls Main: Volume/Bright;  Treble;  Middle; Bass; Master;  Presence
  • Controls OD: Trim; Level;  Ratio
  • Power output: 22 Watts / 33 watts
  • Preamp Tubes: 3 -12AX7
  • Power Tubes: 2 – 6V6
  • Rectifier: Solid State Diode
  • Bias: Fixed
  • Choke:  no
  • Speaker:  per customer choice
  • Outputs:  2
  • Speaker Output: 4, 8, 16 switched
  • Voltage Support: 115 V 60Hz – 240 V 50Hz
  • Weight:  Head: 20 lbs., 112 Combo 50 lbs.
  • Switches:  Rock / Jazz;  Mid Boost
  • Other:  Footswitch for PAB (pre-amp boost) /OD; Effect In  /  Out
  • Chassis Dimensions:  17″ W X 2-1/2” H X 8-1/2 ” D
  • Circuitry based on Dumble ODS #124 Skyliner


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