[Niteshade]

NS-40 with optional faceplate


The Niteshade Audio NS-40 6L6 tube stereo amplifier is based on a reduced component circuit that was developed to provide exceptional articulation, a low noise background and enough power for superb dynamic range even with difficult loads.

I thought it would be a good time to re-introduce this amplifier because it has far exceeded my expectations. This amp was designed specifically for the 6L6 family of tubes, both new and vintage. Vintage tubes work great because our circuit reduces plate dissipation, which greatly extents tube life as well as making the use of "GA" and metal 6L6 tubes possible. 40 watts from a pair of 6L6GA's? Absolutely! The 6L6 in general has long been my favorite tube because they are rugged, inexpensive and have a clear, clean sound with late breakup and compression. It's as close to the ideal audio output tube as you are ever going to get and our NS-40 demonstrates that well.

What is the difference between the sound quality of a NS-40, 813, 845 and 805 based amplifiers? I am comparing it to moderate power single ended amps because that is what this model reminds me of the most sonically. The NS-40, in my opinion, breaks the mold regarding push-pull amplification. It's powerful, liquid and expressive of minute details. It has a sound stage that is non-fatiguing, presence that's realistic and a linear frequency output that doesn't leave anything bloated or attenuated. Variable feedback and tunable biasing provide an unequaled, unparalleled method of peaking the amp's performance as well as acclimating it to your existing system. Tube rolling is fun, biasing is ridiculously simple. 

There are several upgrades available. Here are a few:
1] Regulated D.C. Filaments: Completely eliminates ALL filament-based EMI for a super low noise floor.
2] SE Upgrade: The D.C. package + an enhanced voltage amplifier for double the resolution.
3] Tube/Solid state rectification: Flip a switch convert from one to the other.
4] Wood wrap: We have around 30 wood types to choose from. Dove tail joints!
5] Faceplate: Solid aluminum faceplate in black, gold or aluminum.
6] Color: Custom colors are free of charge!

Interesting features:
1] Point to point wired
2] Made in the USA with primarily USA made components.
3] VERY low heat output
4] Internal components operate cool and are not stressed
5] Extended tube life
6] Not excessively heavy @ 30lbs
7] 240 watt HV power supply (loafs along at full output)
8] All electronic components are chosen for optimum operational synergy

If you have any questions, please ask!

Small revision: It has a 240 watt B+ power supply.

[Niteshade]

Different enclosure options:




Shown is a rack mount, our new anti-resonant, bi-metallic enclosure in American Chestnut and a NS-60SE in quilted maple.

Wood side panels can be installed on the rackmount enclosure too.

[targa02]

I am the owner of the amp at the top of this thread.  This amp puts a smile on my face everyday.   There is great separation between instruments and it is very clear and detailed, all the while being very musical. 

[Niteshade]

Some favorite upgrades for the NS-40:

1] DC Filaments
2] Dual rectifiers (or single rectifier) complete with switchable solid state rectification

There are several options available, however I believe that with the base configuration of two driver tubes, the ones listed above are ideal.

What these features can do:

DC Filaments drops the noise floor considerably. In fact, it can be lower than many solid state amps.

Switchable tube/solid state rectification makes it possible to change the amp into more of a soft tone. Dual rectifiers stiffens the B+ considerably over a single rectifier, yet it's still a bit softer than diode rectification. Diode rectification offers the most neutral output and is necessary for full output, which is nearly 50 watts per channel. The NS-40 is under rated.

[jtwrace]

What's the output impedance of your amps?

[Niteshade]

There is a switch on the back for speaker impedance. Either 4 or 8 ohm speakers can be used. The variable feedback setting can be used to reduce output impedance to nearly any load, as long as the speakers' nominal impedance is either 4 or 8 ohms.

That's not a precise answer, but I would have to say as low as a one ohm dip is permissible on the 4 ohm tap and around 3 ohms on the 8 ohm tap.

[Jed]

I see the amplifier is 20hz-20khz in the specs, but what is the tolerance and do you have THD ratings?

Also looking forward to the EL84 super amplifier version of this amplifier.   Hopefully that is still in the cards?

Jed

[Niteshade]

Plans for the Superamps are going forward! A Superamp is one which uses four tubes per side to obtain the same wattage as two tubes. The only model which will actually provide more wattage with extra tubes is the EL84 Superamp, which will provide 40+ watts per channel.

Idea behind the Superamp models: Using more tubes to obtain the same wattage, such as 4 6L6's to produce 40 watts greatly increases tube life. It also provides a better current source to the speakers since the power tube section (primary of output transformer) will have a 50% lower impedance. It is akin to using whole milk to make your hot chocolate instead of water. This design brings complex passages and/or ones that are the most demanding more up front for a fuller, richer sound stage. Our standard models do a superb job at this due to beefy power supplies, however, I wanted to provide another step up.

Specifications other than those published are not available. My own tests are for peak and RMS wattage plus frequency response. Each individual amplifier is thoroughly tested for perofrmance before it's packed and shipped.

[Jed]

Specifications other than those published are not available. My own tests are for peak and RMS wattage plus frequency response. Each individual amplifier is thoroughly tested for perofrmance before it's packed and shipped.

What is the frequency response tolerance, +/- ? db?  Do you think the EL84 version will have equally flat response as the 6L6 versions?

What quality output transformers are used in your amplifiers?  Sorry for all the questions but the EL84 superamp has my attention.  You're not that far away from me, and I could possibly try your amplifiers on some of my loudspeakers that I've been developing.  I should be done with most of them in March.

[Niteshade]

I'd like to try my amps with your speakers!

The only two measurements I have ever published are frequency response and power output. Reason being: Other measurements do not convey how the equipment sounds.

I have listened to multiple amps with the same written spec's and could never find two that sounded alike. That is why I never went forward with other specifications. Power and frequency response numbers plus a written description (review) on the amp's performance provide the most accurate way to determine if an amplifier will work positively in a system if it can not be listened to.

The El84 version  (NS-40SA) will have the same frequency response.

If you would like, we can talk about amplifiers when you have the chance.

Note: One of the specifications I recently started posting is power supply wattage, specifically for high voltage. This number provides a very good indication of performance. Delivery quality is enhanced when there is an abundance of good, clean, stable DC to modulate. As the impedance of a speaker system drops at specific frequencies, it puts a heavy load on the power supply. A big power supply also aids greatly with cone control. Third, it provides headroom for transients.