This is Not Your Grandfather’s 300B
- The NiWatts continue to amaze people with their ability to drive difficult loads. Check this blog post to read about their encounter with a pair of Von Schweikerts.
- If you love the tonal beauty of the 300B tube, but long for more dynamic authority and rhythmic speed, the NiWatt is your amplifier.
- If you are trapped between the delicacy and beauty of a 45 or a 300B, and the sense of unrestrained power of a 20 watt 845, the NiWatt is your amplifier.
- Your grandfather’s 300B was about tonal beauty. The NiWatt pays respect to this aesthetic while building on it.
Shown at the left is the simulation of the chassis drawings submitted to our fabricator.
Not shown is a removable tube cage which will be provided to both comply with European Union requirements, as well to provide protection for owners with small children and pets.
Old Meets New
To accomplish this, the NiWatt combines a classic circuit, fastidious attention to layout, and an extreme approach to power supply design. The power supply design was heavily influenced by Lynn Olson and his legendary Karna amplifiers (see below for details).
Shown at the right is a pre-production prototype. Final construction will be metal as shown in the concept drawing, above.
Open the tabs below for more details on topology and design philosophy.
Grace and Power
Visualize the “ideal” ballerina – someone who is a perfect expression of finesse and power – a dancer with precise footwork who is always in time and in perfect balance. A dancer who can bring you to tears.
This is the aesthetic of the NiWatt.
The NiWatt’s calling card is tonal beauty without compromise.
The NiWatt breathes life into your music.
Auditioning
Shortly after going into production, we will be taking the NiWatt on the road, to demonstrate at key locations in the Midwest, Eastern Seaboard and South. Check in with us for details or follow the links posted above for updates.
Click the tabs below for design and construction details.
Mirror imaged pairs
We go to this extra expense in support of implementing the shortest signal path from input jack to speaker terminal.
Short signal path
5″ of solid core silver wire in the positive side of the signal circuit – total! This circuit is so revealing that auditioning various samples of a 3″ length of this wire was clearly audible.
Copper Ground Plane
No expense was spared here. This copper ground plane, along with the extremely short signal path is a key contributor to the NiWatt’s remarkably low noise floor and speed.
Hybrid, point to point wiring / turret board construction
Ease of maintenance, and immunity to shock. This is the same construction method used in guitar amplifiers which are almost impervious to abuse from “roadies”.
Parts matter
Every part must justify its place in the NiWatt – from the 3″ length of wire referenced above, to the smallest resistor, and as noted above, the NiWatt is extremely responsive to parts changes.
The most expensive part was not necessarily the best suited to the task. For example, our NOS supply of Black Gate power supply capacitors did not fare as well as power supply capacitors which could easily have been overlooked if one specified parts based on price or reputation.
Of course, there are places in the circuit demanding of premium parts. The copper ground plane is but one example of this. It’s also no surprise that premium output transformers justify their place in the NiWatt. We are currently specifying output transformers from both Magnequest and Intact Audio.
The key distinguishing feature of the NiWatts are its four independent power supplies (and transformers). This was inspired by living with Lynn Olson’s personal Karna amplifiers for three months while Lynn was relocating to Colorado.
- A pair of power transformers (B+ and filament supply) are dedicated to the 300B output tube.
- A second pair of power transformers (B+ and filament supply) are dedicated to the input and driver tubes.
Separating the output tube’s power supply insulates the input and driver tubes from the harsh demands placed on the output tube. This contributes to the perception of a dramatic increase in power, because the driver tube is never under stress.
It is for this reason that we encourage you to compare the NiWatt with both push-pull 300B amplifiers as well as “transmitting tube” amplifiers like those based on the 845 tube (20 watts). We think you’ll be surprised at how authoritative the NiWatt sounds in comparison.
Damper diodes (tubes) are specified in place of conventional rectifiers. Their high current capability conveys rhythmic speed and their reduced switching noise contributes to delicacy and nuance. Refer to the tube section for more details.
Principle #1: when you listen to music through your hi-fi, you are listening “through” your amplifier’s power supply.
Principle #2: with directly heated triodes (because of their low distortion), you are actually hearing your driver tube. This is the key reason for the four independent power transformers discussed above.
RC coupled
A classic circuit topology which has withstood the test of time.
Direct coupling has its advocates, but we’re not fans because of the benefits conferred by independent power supplies (discussed in the power supply section).
Three stage design – input, driver, and output stage
We are firm believers in separate input and driver stages, because the input tube’s job (voltage gain) and driver tube’s job (current delivery) is very different.
Asking a single tube to perform both functions is like asking your BMW to haul a cord of firewood.
Phase inverting (3 gain stages)
An amplification (gain) stage (either a tube or a transistor) inverts phase, so an even number of stages is non-inverting and an odd number inverts phase. Simple, huh?
Ask your manufacturer, because you can’t just count tubes (and it’s really hard to count transistors). Some tubes have dual sections (which may or may not be used), and other tubes may not perform amplification functions (i.e. cathode follower).
7 tubes:
- 4 damper diodes (6AU4, etc.) in place of traditional rectifiers (2 for the 300B & 2 for the input/driver supply)
- 1 6SN7 (input tube)
- 1 6SN7 (driver tube)
- 1 300B (output tube)
The musical benefit of damper diodes
Most individuals are unfamiliar with damper diodes. They have much lower switching noise, which translates into a less “hashy” sound than even the best new old stock rectifiers.
They also have much higher current capabilities than normal rectifiers. All things being equal, damper diodes follow musical transitions with more finesse and speed.
They are in plentiful supply in new old stock, and as an added bonus, they are priced lower than what you’d pay for current production 5AR4’s from Sovtek, JJ etc.
How does it get better than that?