Why Use A Tube Buffer?
- Improve the sound quality of your existing preamp
- Sand some of that hard digital edge off your DAC’s output
- Add some tube euphonics to your solid state system
- Allows you to use long cable runs between your passive preamp and amp.
- Resolves most impedance mismatches between components
- Drive a subwoofer amp from your passive preamp
- Put more authority and punch into your system’s dynamics
Tube Rolling Is Here!
The TBP.V1 tube preamp buffer allows you to substitute the stock 6H30 tube with any tube from the 6DJ8 / ECC88 / 6922 / 7308 family of tubes which opens up a big wide world of tube rolling possibilities. More info on tube rolling the buffer can be found here.
More Than A Buffer
The TPB.V1 tube preamp buffer is more than a conventional unity gain buffer.
Whereas most audio buffers have only a unity gain buffer stage, the TPB.V1 is a hybrid tube preamp/buffer with an adjustable gain tube preamp input stage as well as a solid state buffer output stage.
Like all buffers, the TPB.V1 tube preamp buffer has no volume control of its own and thus belongs downstream of an existing preamp or source device that has its own integral volume control.
The TPB.V1 is a great match for anyone with a passive preamp who is looking to improve their system performance via tube euphonics and more authoritative dynamics but wants to avoid going back to a conventional active preamp.
For those looking to better understand what a buffer is and what it does, we invite you read our article entitled: Is A Preamp Buffer Right For You?
Put Your Passive Preamp on Steroids
The TPB.V1 tube preamp buffer is ideally suited for use with passive preamps such as Tortuga Audio’s own line of LDR passive preamps but works well with any type preamp.
For passives, the buffer makes impedance matching issues moot and allow the use of long runs of interconnects between the buffer and the amplifier. Moreover, the buffer will drive practically any amplifier load with authority and power and will overcome any weakness that your source(s) may have had driving a passive preamp.
For those driving multiple amplifiers from a single passive preamp, the TPB.V1 will eliminate any impedance issues with driving multiple loads in parallel.
Elegantly Simple Signal Path
The challenge with any active line stage component, including preamp buffers, is delivering a satisfying listening experience that remains true to the source material while simultaneously enhancing the audio signal with minimum ill effects.
The TPB.V1 achieves this through a unique hybrid tube/solid-state design that keeps the signal path short and simple without compromising performance.
Tube Input Stage
The incoming audio signal to the tube input stage connects directly to the triode’s grid with no input coupling capacitor. A 100k ohm input impedance makes the buffer extremely easy to drive.
The input stage uses the 9 pin 6H30Pi Gold triode tube from Electro-Harmonix. We chose the 6H30 because of its growing reputation for sonic excellence, robust long-life, and the fact that it’s a contemporary tube that isn’t likely to go out of production for a long time to come.
We run the 6H30’s at a much lower plate voltage than most other tube preamps. This lowered voltage reduces tube stress and together with its already robust design all but guarantee that the 6H30’s will last indefinitely.
Most importantly, the 6H30 is a delightfully smooth yet muscular sounding tube with just the right amount of tube euphonics.
A Little Gain But Only If You Need It
Most buffers are inherently unity gain devices. Indeed the default gain of the TPB.V1 is also set at unity gain (0 dB) but can be adjusted by the user (via internal jumpers) for either a +3 dB (~1.414 Vo/Vi) or +6 dB (~2 Vo/Vi) fixed gain for audio systems that need a more volume headroom.
Independent Tubes For Each Stereo Channel
Each stereo channel has its own dedicated 6H30 tube to ensure the best possible channel separation. When configured for single-ended audio, only half of each triode is utilized. When configured for balanced audio, each triode handles both phases of its own stereo channel.
Available for Both Single-Ended and Balanced Audio
The tube preamp buffer is designed from the ground up for balanced audio. When configured for singled-ended audio there’s a reduced part count but otherwise everything is the same including the power supplies.
Robust Power Supply
The TPB.V1 has two independent oversized DC power supplies with one dedicated to running the tube heaters and the other providing clean DC power to both the tube and solid state stage signal path.
Because the 6H30 tube draws considerably higher heater current than most triodes, we opted for an oversized 40VA toroidal DC power supply combined with a switching DC-DC regulator capable of powering a pair of 6H30’s with a substantial design margin while minimizing noise and thermal issues.
Given its high current capacity, the TPB.V1 is able to handle the current requirements of almost any 9 pin tube available today. Power supply will not be a limiting factor for those who consider tube rolling to be an official audio sport.
Solid State Output Stage
The actual output stage of the tube preamp buffer is a solid state design capable of delivering the audio signal with ample current at a lower output impedance and using less complex hardware than is possible with tubes alone.
The proprietary Class A output stage uses a field effect transistor (FET) in combination with a constant current source. This low impedance output stage delivers the type of compelling robust dynamics that can really enhance your music listening experience.
The core of the output stage is itself encapsulated in a 4-pin removable and replaceable plug-in module. Future improvements in the output stage module design may be realized by simply replacing the existing output module.
Upgrade Options
The TPB.V1 is designed with numerous potential upgrades in mind for the discriminating audiophile. Current and future upgrades include the following:
Matched Tubes
Matched tubes are now standard and are included in the base price.
For a modest additional cost, we offer a matched set of tubes for the ultimate in channel and tonal balance. Tube matching is performed by our suppliers and as such is subject to availability. An excellent discussion on tube matching can be found here.
Output Coupling Capacitor
A good yet modest stock polypropylene output coupling capacitor can be upgraded to an excellent high performance V-Cap oil impregnated metallized polypropylene capacitor. More info on the V-Caps can be found here.
Output Module
As discussed below, alternative plug-in output stage modules may eventually become available that can be easily swapped out for the stock module.
Specifications
These specifications reasonably reflect the current model but are subject to updating and modification without notification.
| Criteria | |
|---|---|
| Buffer Type | * 2 stage hybrid * 1st stage | direct DC grid input triode with adjustable gain (see Gain) * 2nd stage | Class A solid state FET with AC coupled output |
| Gain | Switchable gain via inconvenient located internal jumpers * 0 dB (default) * +3 dB * +6 dB |
| Input impedance | 100k ohms |
| Output impedance | ~26 ohms |
| Tubes | 2 x Electro-Harmonix 6H30Pi Gold triodes One tube dedicated to each left & right channel |
| Power Supply - Heater | * 40 VA toroidal transformer * 3 amp switch mode DC-DC converter regulated @ 6.3 VDC |
| Power Supply - Plate | * 10 VA shrouded dual bobbin transformer * Linear regulated 30 VDC * Optional Belleson Super Regulator |
| Power entry | * IEC type 3-pin C13/C14 coupler * 120 VAC or 240 VAC switchable via inconvenient internal jumpers * Integral on/off switch with green "on" light * fuse drawer with 1 active fuse plus 1 spare fuse |
| Fuses | * 4 amp external access fuse in power entry fuse tray * 3 amp internal access fuse for tube heater power supply * 0.2 amp internal access fuse for tube plate power supply |
| Controls (rear panel) | * Main power on/off switch (see Power Entry) * 12V trigger input - turns tubes on/off remotely * Trigger manual override switch - local control |
| Indicators | * Green light on power switch indicates unit is powered (see Power Entry) * Blue light on front panel indicates tubes are powered/on |
| Inputs/Outputs | Single Ended Model | * Single RCA input * Dual RC outputs (Cardas jacks) |
| Inputs/Outputs | Balanced Model | * Single XLR input * Singe XLR output (Neutrik Type A XLR connectors) |
| Total Harmonic Distortion @ 1 kHz | 0.6% |
| Dimensions | * 6.0 inches (xx mm) wide * 3.25 inches (xx mm) tall including feet but excluding tubes * TBD inches (xx mm ) tall including both feet and tubes * 8.5 inches (xx mm) deep |
| Weight | * unit weight | (TBD) * ship weight | (TBD) |