Octals are internally factory biased for push-pull amplifiers, which accounts for about 95% of commercially available amplifiers.  A single-ended variation should be coming down the road.  

There are special cases to consider, please see below for more on that.

...

Why do we need Octals?

Nearly all new vacuum tubes are made in just three places: Russia, China, and Slovakia. This limited production makes the supply chain fragile and prices more unpredictable.

After they are made, vacuum tubes have to be sorted, matched, and tested for things like microphonics, transconductance, and stability. Over time, they wear out from heat, use, and vibration, so they need to be replaced regularly.

In my opinion, tubes also handle high temperatures well, sound awesome and I hope they never go away!  But as an alternative to counter some of the issues with vacuum tubes, we came up with the Octal. 

...

How much will they cost and when/where will the Octal be available?

Yet to be determined.  The goal is to be able to offer these to end users, retail outlets, and wholesale distributors alike.  Please sign up for our mailing list, check back here and/or our instagram page for updates.

...

Will the Octal change the tone of my amp?

I am making as many comparison demos and reaction videos as possible to answer this question.  I realize that a recording can only paint so much of the picture.  

My impression is that the additional power can feel like an increase in body to the sound.  The increased headroom can feel like a less compressed version of the sound at high volume.  

When starting this project, a fundamental question was…

How much of a tube amp’s sound is the actual tube responsible for, and how much is driven by the additional circuitry, specifically the output transformer?

After the last couple of years experimenting… we've learned that tubes are an important part of the picture but not solely responsible.  The signal still smears through an output transformer en route to your speaker… that transformer is a reactive component that does much to color the sound of your amplifier, arguably more than the tubes themselves.

Short answer, changing from tubes to Octals is comparable in scale to changing from one tube type to another.  If you’ve ever replaced the EL34 in your Marshall to KT88, for example… on par with that.  

By all accounts your tube amp loaded with Octals will still have your tube amp's personality. 

...

Will the Octals improve headroom in my amp?

Likely yes, though different amplifiers have different power supplies/output transformers and the Octal will respond to each a little differently.  Thus far, we’ve seen clean power increases up to 50% in different amps.  

...

If my amp is capable of putting out more power when loaded with Octals, do I need to consider the power handling of my speaker cabinet?

Yes. If your amp experiences an increase in available power with Octals, your speakers may be subjected to that additional power. Thus, suitable power-handling speakers will need to be used with your Octal-loaded amp to ensure that they are not overloaded.  

It's worth noting that a "100 watt" amp pushed into full power actually puts more power into your speakers than 100 watts.  For example, a common Marshall 1960 412 cabinet is rated for 300 watts and paired with a "100 watt" amp that puts out some amount beyond 100 watts as the output waveform is distorted. I'd expect an Octal loaded "100 watt” amp experiencing a 40% increase (around 140 clean watts) to still be a safe match for a 300 watt Marshall 1960 cab.  

...

Will there be a version for 9 pin tubes such as EL84 amps (some Vox, Matchless, etc…) in the future?

Possibly down the road, depending on demand. 

...

Will the Octals physically fit in every amp?  

The Octals need at least 1.05” From the tube socket center to any neighboring physical obstructions (other tubes/transformers, etc…), this spacing is compatible with the vast majority of amps.

...

Warning!  Nerdy Technical Deep Dive Below

Is the Octal specifically modeled after a particular tube type, ie. EL34 or 6L6, etc…?

The Octal is a suitable replacement for all standard 8 pin tubes.  It isn’t designed to emulate any specific tube model, but rather to do a good job of safely making your speakers wiggle and maximizing the output potential of your amplifier.  

...

What if my amp uses obscure pinout 8 pin power tubes?

If your amp uses a rare 8-pin tube with a different pinout, such as the 7059S, the standard Octal is NOT a fit, but there could be a modified version for such amps down the road if there is enough demand.  

...

Can I use a combination of Octals and vacuum tubes in my amp?

Not recommended.  Early experiments with this have shown that the Octals can dominate the workload unbalancing the power amplifier.

...

Do I need to bias my amp for Octals?

No, the Octal is internally factory biased for safe operation and zero crossover distortion in a push pull amplifier.  

...

What sort of “tube lifespan” can I expect?   

Unlike a vacuum tube, the octal experiences no degradation with continued regular use.  So long as it isn’t physically damaged or exposed to extreme conditions, it should continue to work indefinitely.  

...

Do Octals experience microphonics?

Octals don’t experience microphonics. 

...

What plate voltages can Octals handle?

So far, the Octal has been stress-tested long-term in amps running plate voltages as high as 700 volts.

...

Do the Octal work in cathode-bias amps as well as fixed-bias amps?

Octals are designed to work in both.  There are lots of configurations out there so we’ll keep testing to find and expose any compatibility issues. 

...

Any issues with amps using ultralinear output transformers? 

Early tests with a vintage Sunn Model T, which uses an ultralinear output transformer, have been great.  

...

How about amps that use 8 pin tubes as triode-connected devices?

The Octal doesn't support the rare triode connected configuration, but we will consider a compatible device option depending on demand.

...

How do the Octal’s improve the clean output of my amplifier?  Is this safe for my amplifier? 

Octals are capable of delivering much more drive current than vacuum tubes. Combining this with the fact that Octals don't need a hot heater filament, this allows us to drive more output power per socket than a standard tube.

Other benefits include precise bias current that doesn't need adjustment, and precise transconductance on each Octal.  Also, the Octals don’t have current hungry filaments that need heating, so this gives your amp’s power transformer a little break.

...

What are the small signal parameters/“plate curves” for the Octal?

We will be putting together a data sheet to allow for designers to use the Octal in their creations.  Stay tuned. 

...

How has the Octal been stress tested?

• We ran them clipping in a 700V supply amplifier for hours straight.  

• Ran them below freezing at 30 degrees (F) and above earthly ambient temperatures at 200 degrees.  

• Power cycled 10,000 times.  

• Idled for days on end.  

• Extreme impedance mismatches.  

• And maybe most importantly drop tested at 8 feet.  

Octals survived all of the above at safe operating temperature and maintaining a consistent idle current.  

...

Does my amp need any modification to use Octals?  

Some tube retainers can be a little awkward.  I recommend removing them to prevent scratching your Octal.  The Octal pins have had a healthy grip in every amp socket I’ve tested thus far. 

...

Do Octals get hot? 

The Octal doesn’t use a heated filament, but it still uses a significant amount of power to drive your amp. That power handling generates heat — just like with any component working at high voltage and current levels. The warmth you feel is completely normal and part of the Octal’s safe, efficient operation. We’ve designed it to manage heat reliably, even under demanding playing conditions. For comparison, they don’t get hotter than 300°F, vacuum tubes can reach 500°F.

...

Is there a warranty for the Octal?

We are seeing great results with the Octal in the dozens of amps that we have tested so far, and we are constantly testing more. 

We've designed the Octal to be compatible with all standard push-pull 8 pin amplifiers, but we will never be able to directly test in the 1,000's of amplifier designs that are out there.

Furthermore, for each amplifier circuit out there that I do test, I can’t speak to the many variations of that circuit that may have been built by the different manufacturers over the years. Much less, all the tweaks and experiments each company may have tried along the way. 

Then there’s the issue of who might or might not have performed any number of unexpected mods and repairs.

So for all these reasons, just like a new set of tubes, though we can guarantee Octal functionality, we can't guarantee a specific sound in your specific amp. 

I’ll spend the coming months testing as many amplifier circuits as possible and showcasing—through an obnoxious quantity of documented demos and reactions—how many amps the Octal works well in, along with what firsthand users have to say about their experience with them.

We are excited to launch these after we finish our general compatibility experiments. Our hope is that these extensive tests and demos will give confidence.

...