Trinity OSD Kit
After many inquiries about an Overdrive Special Design kit, we re-designed our OSD into a builder friendly package that meets 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 one foot-switched channel – Clean and Overdrive. The amp uses 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 a Presence control to add sparkle and clarity to your tone. There is a Master Volume control prior to the phase inverter which is very effective at setting the overall volume of the amp.
The power supply uses a diode full wave rectifier and is unique in that it employs a lot of filtering in the power supply (100uf / 50uf X4) . The large filter capacitors help keep the tone tight and focused especially in Overdrive mode!
On the back of the amp, there are two speaker output jacks, a 4-8-16 ohms speaker impedance selector, passive effects loop, OD trim control and Mains and High Voltage fuses.
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 – Rati, an OD master volume control and Level which adjusts the amount of gain and 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 great sounding amp.
16Jul17: Design concept complete – single Board concept; Layout & Schematic complete; BOM with parts selected ; blank Chassis & Heyboer Transformer set arrived.
14Aug17: Prototype Front panels received; selected parts received
17Aug17: Eyelet board built; Transformers located using headphones to find quietest position.
19Aug17: Completed chassis design and laid out the main parts. Ready to punch out chassis for build # 1 mid-September!
18Sep17: Prototype OSD completed using kit design. Layout & schematic tested while Chris Moir built the protoype. We have a working amp – no issues!
28Sep17: Successful Player Testing with Shawn Dore. He owns an original OSD & said the feel was virtually identical & the controls behave the same. He is very comfortable with and the ‘new’ tone which was basically the same. Check out Shawn playing his OSD Shawn Dore Band – OSD Demo
13Oct17: Costing completed; amp is tweaked and ready to roll. Using 25% larger output transformer.
25Oct17: Heyboer Transformers and Chassis have been ordered.
1Nov17: CAD design finalized and submitted for production.
13Nov17: Eyelet boards built; Parts being packed up for kits
27Nov17: Finish Packing kit parts
3Dec17: Finishing off Builders Manual; Transformers shipped by Heyboer
12Dec17: Expected delivery of Transformers
13Dec17: Expected Chassis pick-up
14Dec17: Packing for shipping begins!
Coming 2017. Order Below at Introductory Pricing!
Orange Drop 716 series caps; 1 Watt CARBON FILM resistors; 1% 1W 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″ thick GP03 Eyelet Board with KEYSTONE Eyelets; CARLING switches; 6A impedance switch; GENERAL CABLE 22 gauge solid core coloured hook-up wire and pre-twisted heater wire; BELDEN Co-Ax cable; All Mounting hardware, spacers and nuts; Front Black faceplate with White reverse engraved lettering; Silk-Screened rear chassis; Pre-Cut 0.09″ Aircraft Aluminum Chassis with tapped holes for tube mounting screws; Two-button foot-switch with LED indicators and 15′ DIN connected cable; Detailed 90+ page Builders with large 11″ X 17″ sized schematic and colour layout; Real SUPPORT
Kit Includes Custom Heyboer Transformer set – PT & OT (over spec’d) Made in USA to our 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.
- Channels: 1 switched – Clean / Overdrive
- Controls Main: Volume/Bright; Treble; Middle; Bass; Master; Presence
- Controls OD: Trim; Level; Ratio; internal control for PI balance
- Power output: 22 Watts with 6V6 / 33 watts with 6L6
- Preamp Tubes: 3 – 12AX7
- Power Tubes: 2 – 6V6 or 2 – 6L6 (switched transformer impedance)
- Rectifier: Solid State Diode
- Bias: Fixed, externally adjustable with test points
- Choke: no
- Combo Speaker: per customer choice
- Outputs: 2
- Speaker Output: 4, 8, 16 switched
- Voltage Support: 100V, 120V, 200V, 230V, 240V @60Hz / 50Hz
- Weight: Head: 20 lbs., 112 Combo 50 lbs.
- Switches: Rock / Jazz; Mid Boost
- Footswitch for PAB (pre-amp boost) /OD
- Passive Effect – In / Out. Optional FET buffered effect loop with pre-amp 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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All prices are listed in US dollars. Orders ship from Brighton, Ontario, Canada, applicable taxes not included. Specifications and prices subject to change without notice.
Trinity Amps Inc.
+1-613-438-5854 Canada EST
14656 County Rd. 21