Tubes are now back in stock!

Is it a Vacuum Tube or Electron Valve?

Did you know that Americans and English have different names for vacuum tubes? What Americans call "Tube," the English call "Valve."

This may seem a bit odd to us Americans at first, but while "vacuum tube" refers to just the physical nature of the device, the English are referring to what it does.

A vacuum tube conducts electricity by creating a stream of electrons in a vacuum. To do useful things with this (like amplifying signals), we have to be able to control this stream, to make the flow higher or lower.

You can think of this as a valve controlling a stream of water running through a pipe. Water (current) runs from high-pressure end to low-pressure end, and you control this like a valve.

Hence the name "Valve."

So now that you understand how a tube works, the name "valve" kind of sticks, doesn't it? Leave it to English to be precise about the names of things, but in this case, we think the English have it right.



About 12AX7LPS Vacuum Tube

Sovtek 12AX7LPS is underrated. And by that I mean, way, waaay underrated.

Let me explain what we mean.

Sovtek 12AX7LPS was one of the first modern long plate 12AX7 tubes. The long plate Sovtek 12AX7LPS is quiet, well made, has nice thick low-mids that translates into that warmth that we all seek.

12AX7LPS tube is designed with low noise in mind. Longer plate tubes such as 12AX7LPS can be more prone to microphonics. In order to address this, the plate assembly is crimped precisely onto the supporting rod. Also, the micas are cut clean, and sized just right, so the plate assembly is well supported.

Despite the tight fitting of micas, we hardly ever see bits of mica floating around in a Sovtek 12AX7LPS. The tube heights are very consistent since the plate assembly is brazed to the pins at a constant height.

Considering a lot of the assembly is done by hand, we take our hats off to the people working at the Xpo-pul factory in Saratov, Russia. All of these details require precision and skill that make Sovtek 12AX7LPS such a solid reliable tube.

The best attribute of Sovtek 12AX7LPS tube is that it is a great value. Sovtek 12AX7LPS is not the cheapest 12AX7, but is definitely one of the cheaper choice and a great value.

One small quirk of Sovtek 12AX7LPS is that the filament is completely encased in a metal tube. This makes it hard to see if a Sovtek 12AX7LPS is turned on or not. This was done so as not to expose ends which can cause noise. If you don't see the filament glow on a Sovtek 12AX7LPS or its brother Mullard 12AX7, there is no need to worry as this is perfectly fine.

As you can probably tell by now, we are big fans of Sovtek 12AX7LPS, especially in audio applications. Being sellers of vacuum tubes we probably should be trying to promote more expensive tubes, but we think Sovtek 12AX7LPS is such a great performer and value that we can't help keep recommending it for audio applications.

You can find our Sovtek 12AX7LPS offering on the following pages:

Also feel free to check out other 12AX7 tubes we carry:


Little Dirty Secret About Tube Prices

If you ever shopped for vacuum tubes for your amp, you must have noticed that the prices can vary significantly for the same type. In fact, it’s not uncommon to see price differences of 5 or even 10 times between the least and most expensive tube of the same type.

Why is this, and more importantly, is the expense worth it?

Well, we have tried to provide some answers below.

Quality and Scale

Over many years of testing and selling tubes, we found that assembly quality does correspond with the price to some extent. Why would that be?

Well, it takes skilled labor to assemble the intricate innards, braze many pins and pull a strong vacuum when melting the glass tubes shut. And it takes a very skilled workforce to do it consistently well. All of this comes at a cost.

This is not to say that lower priced tubes are always of less quality. Some tubes are quality build and priced lower. This is often the case with tubes that are shipped in amps from the factory. Amp manufacturers demand tubes that won’t cause costly warranty issues. Amp manufacturers require lower cost too. Tubes that are shipped in amps are made in high enough volumes that allow the scale of economy to drive the price down while keeping quality high.


There is another more obvious reason why some tubes are priced much higher. It’s them gold plated pins.

Gold is often used on electrical contacts for reliability. Vacuum tubes are installed in sockets where pins make contact with socket receptacles, and the same applies here. In fact, when vacuum tubes were used in mission-critical equipment that required high reliability, they plated the pins with gold for the same effect.

Gold, as we all know, is not cheap. It’s also not easy to plate the vacuum tube pins consistently with the correct thickness of gold. We once had a stockpile of gold pin tubes that we couldn’t sell, because there was just… **too much gold**. The gold plating of the pin was too thick, and they wouldn’t fit into a socket. This was a costly mistake for the manufacturer who had trouble with quality control in general. That manufacturer has now been defunct for some time.

Now, here’s a question though. Is gold plated pin really worth the cost today? Tube amps are not used in an extreme environment, so from a practical standpoint, it doesn’t seem so. Here is the thing, though. For us tube amp aficionados, it’s not always about being pragmatic. Aesthetics and the pride of ownership is a big part of the pleasure of owning such a piece of equipment, too. If you own a beautifully designed amp that incorporates gold plating on every contact and socket, why wouldn’t you get tubes with gold plated pins also? It only seems proper for such a piece of equipment.


Vacuum tubes were mass produced in the US, UK, Germany (both) and other European countries from the 1940s until 1980s. Once tube factories in these countries shuttered, these American/British/German/Dutch tubes were no longer being manufactured.

There were stocks of these vacuum tubes, especially by the military in each respective country that stockpiled enormous volume. These stocks supplied the market for many years. As the years went on and these vintage American/European tubes became scarce, the ones in demand have entered more or less collectible status.

Prices of such tubes are entirely driven by market pricing. It may be hard to justify some of the pricing on these tubes, but on the other hand, you are likely to get similar pricing should you decide to sell it. So perhaps it may not cost you so much in the end if you only want to try. YMMV, of course. We don’t deal much in such tubes but there are tube vendors who specialize in it, and they can tell you more about it.

What's The Secret, Kenneth?

If you haven’t set your heart on collectibles or high-end tubes, one secret we can share is that re-tubing worn out tubes, especially the power tubes regularly is more important than what brand you replace with. The sonic difference between different tube makes is subtle compared to what you lose with worn out tubes.

The tubes wear due to heat, and heat dissipation is governed by the laws of physics and not so much by price. You just don’t get extra longevity by paying extra. A set of worn out pricey power tube can easily be eclipsed by a new less expensive set. So you are better off re-tubing more frequently with tubes that offer good value rather than tubes that carry top-of-the-line pricing.

To help you make such a selection, we have several pages to help you guide which tubes to buy below. We hope it would be of some help. Oh, and may your tube amp live long and prosper.


Added a page about Emission Tester

Hello, and oh boy, we haven't updated this blog in a long time....!

We just added a page about Emission Tester and 12AX7.

The TL;DR of this page is that vintage Emission Testers have problems testing current production 12AX7 tubes. The page is our attempt at explaining this. You can find the same info on other sites as well.

This is a topic we have been wanting to cover for some time, and we recently had a few inquiries in a row. One was from a customer who purchased 12AX7 from us over a year ago...! This made us realize that this is a good information to have on our site, as it can result in a poor customer experience if this information is not known in advance. We hope the page can be of some help.


Marshall Tube Set

We added Marshall Amp Tube Set to our site some time ago. We are offering TungSol tubes (except for JJ EL84) for tube sets.

Why TungSol? Well, we have been shipping TungSol tubes for many years. And TungSol tubes have not only sounded great, but have been solid and reliable. If you are looking for tube sets for your Marshall Amps, you should definitely check them out.

Now, you may have noticed that all the photos on our site are unique to us. That's because we take all the photos ourselves. It took us many years to get the tube photos right. Glass is hard to photograph especially if you want to overexpose the background. If you are trying to take photos of tubes and not having luck, we'd be happy to let you know how we do it.

For tube sets, we are photographing our own amps as well. For the Marshall Tube Set, we asked our very own glamorous classic JMP to be our photo model.

Marshall JMP Photo Shoot

Now between you and me, JMP was actually very difficult to shoot. We wanted to feature her lines and show off her gorgeous dark surfaces. But the black British Tolex bounces off a lot more light than you might expect. This made her surface look like they are covered with tanning oil.

In the end, it took a lot of adjusting the lights, and liberal use of polarizing filter to see through her glow. We're happy how she came out in the photo.

What do you think?

Marshall JMP with Tubes For Amps


Guide Pin and Octal Base

We added an article about broken guide pin and what you can do about it.

Let's talk a little bit about octal base. On octal tubes, the base serves important functions.

Octal tubes like EL34 actually have wire leads coming out from the glass. The leads are soldered inside the octal base pins. These pins are what makes contact with the socket receptacles.

This pin soldering is tricky to do well. Quality of this soldering work tells a lot about the quality of the manufacturing.

The octal base has to meet a lot of demands. Octal base insulates high voltages between the pins. Octal base is cemented to the bottom of the glass tube. The octal base also needs to conduct heat away. Octal base must be flexible enough to accommodate thermal expansion of glass tubes. And octal base has to be cost effective.

For these reasons, tube manufacturers use plastic in octal bases. Even the metal bases use plastic, as seen on this Svetlana KT88.

Kt88 Svetlana

Being made out of plastic makes an octal base more prone to blemishing and, of course, guide pin breaking off.

Octal base itself does not affect the sound of the tube at all. But you want to exercise some caution when installing/removing the tube from the socket. Guide pin on the octal base happens to be the most fragile part of the tube.


Welcome to 2017

New Year
New Day
New Month
New Hopes
New Resolutions
New Aspirations

and of course, the world is a better place with

New Tubes For Amps

Happy New Year!

PS: We are closing down our old BOI AudioWorks site. If you got redirected to and don't see what you are looking for, please feel free to contact us at info at

Also from Mari to Japanese visitors:



One year report

So, we didn't update the blog for almost a year....! Our apologies, our old site at BOI AudioWorks is attracting quite a bit of traffic still, so we have been quite busy serving both.

Now with that out of the way, we thought we'd share our reflection of our first year.

TFA is 1 year old

We'd like to take this opportunity to thank all those who ordered from us, we hope you are enjoying the glow and sonic warmth of your tube gear.

Those of you who reached out to us, you know how we enjoy hearing from fellow tube gear users.

Mobile is Awesome

This site has been doing quite well. It is serving traffic from all over the world, and has stayed up for months at a time with no unplanned downtime.

As we continue to make improvements to cater to users who visit this online store, there is one thing we noticed. There is a definite continuing shift to mobile devices.

It's fascinating to think that we are using a handheld device to browse and purchase vacuum tubes of all things...!

This is amazingly futuristic, modern and retro at the same time.

Awesome Journey

When we started selling vacuum tubes online back in 2003, we never would have imagined our customers would be reading our sites and purchasing vacuum tubes using phones and tablets. We have come a long, long way.

On the other hand, as technology keeps changing, here we are using that very technology to more easily access things that enriches our lives.

Things like vacuum tubes that have provided the same enjoyment to us all since decades ago.

And we think that's about the most fabulous thing.


One Month Report

TFA is 1 month old

It has been a month since we took the new site online. We had a few glitches here and there, but overall things have been working great.

We are now seeing steady stream of customers and orders. Btter yet, some who are long time customers on boiaudioworks site have come to order on It's such a great feeling.

Here are a couple of thoughts we'd like to share from our first month on

Cloud is Awesome site is a custom built eCommerce site running on the latest cloud technology. That sounds fancy, but this technology is closer to us than we might think. This technology is what companies like Amazon and Netflix uses.

We get the same performance, capacity and security as these familiar companies do. This means that we are able to keep IT cost (and hassle) to minimum. All in all, pass on the savings to our customers.

Twitter is Awesome

Although we aren't promoting it much yet, we created a twitter account and started to tweet. Yes yes I know, merchant twitter accounts are boring. That's not what we wanted to do.

We have always been interested in connecting with musicians. Not only that, we also have been interested in connecting with craftsmen/women who build music instruments and components.

And in just one month, we found a number of people on twitter who build beautiful guitars and hand wind pickups. We can only hope to connect with more greta people so we can see all the wonderful work they produce.

So that's our 1 month report.


Futuristic Vacuum Tubes

This is a picture of racked MacPros, the beautifully designed Apple's top of the line lightning fast computer.

This company does CG rendering, so it doesn't have a whole lot to do with vacuum tubes, but it's amazing how closely the racked MacPros resemble a tube amp with a matched quad power tubes...!