Eye Catching Amplifiers

Niteshade · « **on:** 16 Mar 2009, 12:04 pm »

Niteshade Upgraded Single Ended Series

Remember that Niteshade Audio is flexiable. The model shown is a 10 watt per channel single ended amplifier using F2A power tubes and special high quality wafer sockets. The best sub for an F2A is a 6550. There is little, if any difference sonically.

Special Features:
One Electron output transformers
Choke Filtration
Zero feedback design
Tunable Biasing
The most efficient circuit available
Tube rectification
Color of your choice

Price as seen with 6550 tubes is $1,800.00 with shipping included.

We're always open to questions!

stereocilia · « **Reply #1 on:** 16 Mar 2009, 02:06 pm »

I have a question:

I have seen a number of solid state amplifiers with a signal-sensing auto-on feature. Most amplifiers with this feature are mid-fi, but some high-end amps have a 12v trigger. I know, this is not exactly the audiophile way, but I wonder if a tube amp would benefit from such a thing.

This would appeal to me, and what happened to me today is a good example why: as I'm getting ready for work I like to have some tunes playing, or the radio on. I forgot to turn off the amp on my way out.

richidoo · « **Reply #2 on:** 16 Mar 2009, 02:16 pm »

Good idea. I hate discovering that I left the tubes running for hours after the music stopped. An external accessory to control the power cord connection, maybe with a tube hour counter would be cool.

CSI · « **Reply #3 on:** 16 Mar 2009, 04:29 pm »

Interestingly, some tube preamps (Cary SLP-03 for example) have 12v triggers for turning remote amps on/off. Of course, you have to remember to turn the pre off and some folks think it best to leave preamps on all the time to avoid tube aging power surges....

Niteshade · « **Reply #4 on:** 16 Mar 2009, 10:49 pm »

Tube Amp timers...

There's two ways to do this:

1. Put your amplifier on some kind of digital timer so the entire unit turns off after so many hours
2. Put the high voltage on a timer circuit so the filaments stay warm, yet the amp is 'off'.

Option #1 would be the least expensive since any electronic timer could do this. Option two would have to be installed inside the amp and that could get expensive.

A 12V trigger: Not a bad idea- just as long as your preamp can produce the control voltage.

stereocilia · « **Reply #5 on:** 17 Mar 2009, 01:58 am »

What about the signal sensing strategy used in some solid-state amplifiers and subwoofers? The reason I think this would be an ideal solution from a convenience point of view is that a source such as a squeezebox could be left on all the time with no need for a trigger other than the presence or absence of music. It's weird to think of how that might work in a tube amp. I am guessing that the time constants would have to be really long for that to make sense, maybe several minutes. Also, tube amps, if I understand correctly, don't just start and stop on a dime.

Sorry if this is sort of a silly question, like maybe I'm missing the point. (Like saying the Ferrari Enzo would be a better car if it had bigger cupholders. Yeah, it would -- but that's missing the point).

Niteshade · « **Reply #6 on:** 17 Mar 2009, 10:31 am »

All nifty ideas!

The big question: How much are these extras worth to you?

I like the signal sensing idea for manipulating the high voltage power supply. If there is no signal for around 10 minuets, turn the HV off. Leaving the filaments on will not harm a tube.

We're open to a host of tube amp topics- jump in!

stereocilia · « **Reply #7 on:** 18 Mar 2009, 12:35 am »

I'm going to say between $200 and $500. I think the price I'm willing to pay also depends on how many competitors have this feature -- right now no other tube amp I've ever heard of has it. There's no way this idea is unique, surely some amplifier designer or two has considered this and scrapped it for some reason or another.

Niteshade · « **Reply #8 on:** 18 Mar 2009, 10:58 am »

That's a good price range. You're right about the idea not being unique. Any uniqueness will be in the circuit used. It probably hasn't been used because there are marketing concerns. I believe it's a GREAT idea! I don't like leaving amplification equipment on unattended, whether it's solid state or tube. If nothing else- there's the electric bill. Imagine- an Energy Star rated tube amplifier! (It could happen- maybe..)

Niteshade · « **Reply #9 on:** 20 Mar 2009, 11:36 am »

Some tube amplifiers can take either 6L6 or EL34 tube varieties. All it takes is a bias adjustment at times.

How many of you have tried either tube in your amp? I believe how the tubes react has much to do with the driving circuit, but there are most likely some underlying basic qualities that seperate them.

For example: The NS-50 will take either tube. 6L6's produce a more vibrant tone than a El34 in this amp. The EL34 is more forceful, produces more power and it seems to favor the bass region and provides a fuller (wider) midrange.

I thought the differences were very interesting and enjoyed the tone of either tube.

jman66 · « **Reply #10 on:** 20 Mar 2009, 03:43 pm »

Blair,

Are you saying EL34's produce more power than even the 6L6WXT+'s when used in the NS-50 ?
Can you comment about EL34 vs. 6L6WXT+ vs. KT88 power comparisons ?

-jim

Niteshade · « **Reply #11 on:** 20 Mar 2009, 11:22 pm »

The WXT+ is a very good, high dissipation tube. It works about the same as a EL34 in an NS-50. If you are looking for a different tone, then try the El34.

jman66 · « **Reply #12 on:** 21 Mar 2009, 02:11 pm »

Quote from: Niteshade on 20 Mar 2009, 11:22 pm

The WXT+ is a very good, high dissipation tube. It works about the same as a EL34 in an NS-50. If you are looking for a different tone, then try the El34.

Blair,

I asked about power differences.

So "works about the same" infers the 6L6WXT+ and EL34 produce the same amount of watts in the NS-50
but what exactly is that figure?

-jim

Niteshade · « **Reply #13 on:** 21 Mar 2009, 04:37 pm »

Jim,

I have noticed around a 5 watt difference with your transformers and the EL34 or WXT+ tubes vs standard 6L6GC's. It's worth it to give the EL34 a try. I think you'll like them.

jman66 · « **Reply #14 on:** 22 Mar 2009, 12:54 pm »

Blair,

Thanks for the info!
And certainly beneficial to mention a tone difference between the WXT and EL34 tubes.
With your minimalist and straightforward design, the tubes and their characteristics can really shine.

What's your opinion on tone & flavor being more influential up front in the driver tubes versus the output tubes?
Or would you say they both go hand-in-hand in achieving a desired tone and output?

-jim

Niteshade · « **Reply #15 on:** 22 Mar 2009, 11:22 pm »

I would have to say there will be more of a noticeable change between power tube types than driver tube types in the NS-50. A customer of mine likes TungSol 6SN7GTB's, but they are much noisier (cathode leakage) than the Chinese 6SN7GT's. I have noticed that cathode leakage is what produces the most noise in tubes such as the 6SN7, 12AX7, etc... ( I threw that in there to see what others thought about it...)

Niteshade · « **Reply #16 on:** 24 Mar 2009, 02:09 pm »

I was talking with a customer regarding tube choices for the NS-50. Here is what we agreed on:

1. The 6L6GC by JJ/Tesla is forward and brighter sounding (not overly bright)
2. El34's (I didn't ask what kind.) Are more 'organic' and not as forward

My experience with El34's was exactly the same as my customer's and I used Electro Harmonix El34's.

During the tests, the NOS General Electric 6SN7GT's were never exchanged for a different pair. Rectifier tube used was a 5U4G.

I want to share these notes as a means of describing how easy it is to tailor a NS-50 to your requirements. The easy biasing setup as well as variable negative feedback are tools that can make it a cinch to customize the amplifier yourself.

For more information and other view points, check out the Limited Edition's reviews.

NOTE: Tube amplifiers run better with forced air cooling. A small 4 inch or 10 inch desk fan running on low, angled so the fan's output catches the power tubes and power transformer WILL improve sound and increase tube life by at least 50%. Tubes and audio gear run better cool. The same rules apply to warm running solid state gear. HINT: Lube the fan bearings with a high quality machine/electric motor oil. It will operate quieter.

Niteshade · « **Reply #17 on:** 26 Mar 2009, 11:10 am »

What does gas do?

1] Hissing Noises
2] Unexpected popping noises
3] Grunts & Groans and maybe one big "POP!

" during warm-up
4] Constant white noise when there wasn't any before

Power tubes can do all these things, but most people hear them in small signal tubes. A power tube will most likely start to glow red while its siblings remain cool-plated. Sometimes a tube can start oscillating as well due to gas.

Gas comes from warming up the metal within a tube. If you think about it, this is true of just about anything that's heated up.

My suggestion is to run your tube equipment as cool as possible. Air flowing over a tube amplifier can greatly extend the tube's life. A small quiet fan of some sort that can be directed at your equipment is the ideal way to promote better sound and dramatically increase tube life.

NOTE: As I make a new topic, the main topic will be changed as well. It may not match everything else that's being posted.

Niteshade · « **Reply #18 on:** 28 Mar 2009, 04:12 pm »

One of my favorite amplifiers to design is the 5 Tube Variety. Here's a 1940's rebuild I did last year:

The above amplifier is one of my favorites! Interestingly, output power is around 8 watts per channel. I kept it there so the decades old iron would not be taxed and for one other important reason: It sounds unbelievably good! She's running around 40% of her rated output capacity. It takes two hours for the power transformer to go past mildly warm. This amp should easily last another several decades. Note: I called it a phase-splitterless design. Below I will refer to it as self-splitting. They are one in the same.

Getting back to the sound: A clean, vibrant, realistic sound stage is immediately noticed. An assuredness typically found in much more powerful amplifiers is witnessed during demanding movie scenes. Superior resolution insures nothing is missed during critical listening sessions. The self-splitting circuit we use insures Class A operation all the time. Class A without the heat dissipation is a pleasure to the ears AND easy on the tubes and power supply. Why does it work so well? It's considerably more efficient than a single ended design yet contains 50% of the circuitry of a conventional push-pull setup. The output tonality is not as 'organic' as a single ended amp, but it's absolutely cleaner when pushed. This is a unique design and it deserves more recognition than I have been giving it.

I hope this topic brings up some comments and questions!

An amp that sits in between single ended & standard push-pull topologies is exciting technically AND to listen to.

Niteshade · « **Reply #19 on:** 28 Mar 2009, 11:55 pm »

I forgot to mention that the 5-Tube circuit works best with the configuration pictured in the above post: Output iron should be rated for at least 25 watts. The power supply should have a large choke installed and tube rectification is ideal. I have made these up to 20 watts per channel with terrific results.