

©2011 Bruce Clement, BC Audio, San Francisco
Other copyrights and trademarks are the property of their respective owners. Duh.
hand-
Can I buy BC Audio amps with NOS tubes?
Can I install tube types other than those you specify?
Do I need to set the bias when I replace the tubes?
Are BC Audio amps geared more toward humbucker guitars or single coil guitars?
Are they quiet, you know, when I'm not playing?
Will they run on European 220/240VAC power?
What is the difference between the 15w and 25w versions of Amplifier No. 7?
Why not EL84s? You know, like every other 10-
Is 25 watts really enough power? It is much quieter than a 50 watt amp?
Can I use 6V6s and a 5Y3 in Amplifier No. 8?
Is Amplifier No. 9 your take on a Marshall JTM45?
Does it make sense to have an effects loop in a non-
How does the effects loop work? Is it compatible with my gear?
What does “Individual Output Tube Bias” mean?
Is Amplifier No. 10 your take on a 50w plexi?
How does the effects loop work? Is it compatible with my gear?
What does “Individual Output Tube Bias” mean?
Do the ammo can amps get hot? Why don't they have ventilation holes? Or a fan?
Why is everything on the front panel? Why not put the power and speaker jacks on the back?
How did you come up with the ammo can idea?
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Why those funny octal preamp tubes? Why not use 12AX7s like every other guitar amp on the face of the earth?
I'm certainly don’t dislike 12AX7s. They -
Can I buy BC Audio amps with NOS tubes?
Aside from the NOS (new old stock) 5Y3 that I supply with the 15w configuration of
Amplifier No. 7, all tubes supplied with BC Audio amps are new production tubes.
If you really want NOS and don't already have your own stash, I can furnish you
with them. If you already have your own stash of old glass, great! If you are new
to NOS, I would suggest that you do a little research. Get a variety of opinions.
Talk to NOS tube sellers, ask on the forums, read tube shootouts. In the end, everyone's
idea of what is best will vary, and no one knows what is best for you except you.
Which is why I don't offer an option to buy with NOS tubes by default. But, again,
I can work with you on this -
Can I install tube types other than those you specify?
For the preamp tubes, you may substitute a 6SN7 for the 6SL7 in any positions. This
will lower the overall gain of the amp, much like substituting a 12AY7 for a 12AX7
lowers gain in amps that use those. You will get different results depending on
which 6SL7 you replace. Generally speaking, the most noticeable change comes with
swapping V1, the first preamp tube (refer to the Owner’s Manual). Please pay the
extra cost for low-
For the power tubes, some substitutions are acceptable, some are not. In Amplifier
No. 7 and No. 8, 6L6s will work in place of 5881s, but many 6L6 derivatives, such
as the KT66, 6550, 7027 and 7581, as well as other popular types like the EL34, KT77,
KT88, draw too much heater current and may damage the power transformer. Only small-
For the rectifier, you may use a GZ34/5AR4 in with 6V6s in Amplifier No. 7, but understand that the life of the 6V6s will likely be shortened. Do not use other rectifiers such as a 5AU4 or 5U4 in Amplifier No. 7 or No. 8, as they draw too much heater current and may damage the power transformer. Do not use a solid state replacement module in place of a tube rectifier, unless it is designed to emulate the rectifier you are replacing, in which case, why not just use the real thing? If you change the rectifier in Amplifier No. 9, you must heck and adjust the bias. If you don’t know how to do that, take the amp to a reputable tech for that service.
Do I need to set the bias when I replace the tubes?
In Amplifier No. 7 and No. 8, no. These models are cathode biased, and designed
to operate properly with a wide range of hot-
Preamp tubes never need biasing or matching. Yes, you should buy matched pairs of power tubes.
Are BC Audio amps geared more toward humbucker guitars or single coil guitars?
They’re not! I'll readily admit that I am a Les Paul guy. But I also play single coil guitars including Strats, Teles and my lovely 1956 Les Paul Junior, plus guitars with mixed pickups and coil taps. BC Audio amplifiers have a purity an clarity that brings out the character of whatever guitar you plug into them.
A little story: I was showing Amplifier No. 7 at a guitar show. I actually had more than one guy come back to my booth to test out a guitar they were considering buying from another vendor, because they somehow knew they would get a true and accurate impression of the guitar by playing it through Amplifier No. 7.
Are they quiet, you know, when I'm not playing?
Yes. I hate noise. Hiss, hum, crackling -
Will they run on European 220/240VAC power?
Amplifier No. 9 and No. 10 have a voltage switch for 120 or 240 VAC usage. By special order, and for a small additional charge, I can build you a 240VAC version of Amplifier No. 7 or No. 8. Contact me.
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What is the difference between the ammo can version and the head box and combo versions of Amplifier No. 7?
Other than the power inlet and speaker jack locations -
What is the difference between the 15w and 25w versions of Amplifier No. 7?
Nothing. They are the same amp, it’s jut a matter of which power and rectifier tubes are installed. Please refer to the Tube Complement section on the Amplifier No. 7 page.
Probably. Depends on your situation. In its 15w configuration, Amplifier No. 7 can
hold its own playing blues or rock in a club, even if it's vocals-
Remember, you don’t have to decide now. The amp itself is the same in 15w and 25w
configurations -
Again, probably. If you need more that that, you should probably mic up the amps. 25 watts may be louder than you think!
Once more, probably. Again, it depends on your situation. Amplifier No. 7 has about
the same amount of gain as most classic non-
Oh, yeah! I have had great feedback from customers on Amplifier No. 7’s clean tones.
And the magazine reviews gush over its clean sounds. The same factors that give
Amplifier No. 7 it’s amazing rock voice make it a sweet, sweet clean amp, too. And
the transition between clean and dirty is incredibly smooth. It’s not either/or.
There are whole worlds to explore in that clean/semi-
Why not EL84s? You know, like every other 10-
In my humble opinion, 6V6s kill EL84s. Eat 'em for lunch. Blow their doors off. Take 'em to the woodshed... I think you get the idea.
Now, 6V6s have a reputation for having a flubby bottom. So does my sister. (I don't have a sister.) Amplifier No. 7 does not have that problem. It has lots of good, strong low end, and the tone is thick thick thick. But it never "farts out" or gets week in the knees.
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What is the difference between the ammo can version and the head box and combo versions of Amplifier No. 8?
Other than the power inlet and speaker jack locations -
Is 25 watts really enough power? It is much quieter than a 50 watt amp?
You might think that a 50w amp would be twice as loud as a 25w amp. But it’s not. A 50w amp is exactly 3 decibels louder than a 25w amp. That’s not much.
The real beauty of a medium-
Can I use 6V6s and a 5Y3 in Amplifier No. 8?
Yes, you can. I don’t offer that option by default, because you already have the flexibility of having killer overdrive at any volume level via the Volume control.
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Is Amplifier No. 9 your take on a JTM45?
No. Amplifier No. 9 features a pair of KT66s and a GZ34 rectifier for 45 watts.
But that’s where the similarities with the classic Marshall end. The preamp section
is vastly different, not only because of the octal preamp tubes, but because of the
basic architecture, lack of tone stack, the built-
Depth is a control that tailors the low-
Does it make sense to have an effects loop in a non-
The answer is, it depends. Which is why I offer the loop as an option on Amplifier
No. 9. The idea of a loop in any amp is to get time-
If you tend to crank the hell out of the amp for power tube saturation, you will
not get as much benefit from the loop, as the effects in the loop are not after all
of the distortion-
How does the effects loop work? Is it compatible with my gear?
The Effects Loop is tube buffered, meaning it is isolated from the rest of the amp by tube gain stages. So, nothing you plug into the Send or Return will load down the signal within the amp. Send is a low impedance source, so it will easily drive any pedal or rack effect. There is enough gain in the Return circuit to fully drive the power amp from a “guitar level” signal. Translation: It will work with your gear.
The loop is non-
What does “Individual Output Tube Bias” mean?
That means that you can set the bias of each KT66 independently. Setting the bias
of each output tube independently means that you can achieve closer matching than
you can otherwise, since even matched pairs of tubes may be off by several mA. And
you can even use un-
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Is Amplifier No. 10 your take on a 50w plexi?
No. Amplifier No. 10 is a 50w 2x EL34 amp, but that’s where the similarities with
the classic Marshall end. The preamp section is vastly different, not only because
of the octal preamp tubes but because of the basic architecture, the location of
tone stack, the two built-
Depth is a control that tailors the low-
Amplifier No. 10 features a Gain Boost and a Volume Boost. The Gain Boost gives you more gain in the preamp section. The Volume Boost gives you an actual increase in volume. Each boost is independently variable at the amp’s front panel, and switchable via the included remote foot switch.
The two boosts provide for four different combinations of gain and volume, much more
than most channel switching amps. As a gigging guitarist, I know the feeling of
coming to my solo and no matter how much I slam the front end of the amp with a pedal,
it just doesn’t get any louder. That’s where the Volume Boost comes in. You can
dial in a little or a lot of Volume Boost, and when you hit that foot switch, your
overall volume will increase, without changing your tone. The Gain Boost can be
engaged for high-
How does the effects loop work? Is it compatible with my gear?
The Effects Loop is tube buffered, meaning it is isolated from the rest of the amp by tube gain stages. So, nothing you plug into the Send or Return will load down the signal within the amp. Send is a low impedance source, so it will easily drive any pedal or rack effect. There is enough gain in the Return circuit to fully drive the power amp from a “guitar level” signal. Translation: It will work with your gear.
The loop is non-
What does “Individual Output Tube Bias” mean?
That means that you can set the bias of each EL34 independently. Setting the bias
of each output tube independently means that you can achieve closer matching than
you can otherwise, since even matched pairs of tubes may be off by several mA. And
you can even use un-
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Do the ammo can amps get hot? Why don't they have ventilation holes? Or a fan?
A fan? Are you kidding me? Sure, like all tube amps, they get hot. But they never get too hot to put out perfect, beautiful tone for hours on end.
During their development, I put prototypes through truly brutal stress and heat testing.
They never broke a sweat. No burned parts, no melted iron, no weird noises, no fading.
Just unchanging flawless operation under severe conditions for extended periods of
time. And every single amp goes through a burn-
Besides, consider the typical tube amp head. It is closed on the top, bottom, sides and front. On the back it may be somewhat open, or covered with a perforated metal panel. BC Audio ammo can amps are completely open on the front. That’s at least as good as partially open on the back.
As it says on the sticker inside the lid, "Case will get hot. Don't worry about it."
Why is everything on the front panel? Why not put the power and speaker jacks on the back?
Several reasons:
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How did you come up with the ammo can idea?
The idea first came to me when I was a teenager back in the late 1970s. I was already
building amps, pedals and other gear for myself and my friends. One day, I was in
an Army/Navy surplus store and spotted a couple of the now familiar olive drab metal
boxes. I thought, “Wouldn’t it be cool to build some kind of guitar gear in one of
those things?” I didn’t even know what I wanted to put in there -
Some years passed before I acted on that thought. In the mid-
I was working on an idea for my next ammo can tube preamp when it hit me. I didn't
want a preamp, I wanted what my Marshalls and other amps were giving me -
So, you could say Amplifier No. 7 was five years in the making. But it really is more than that. It is the realization of a vague but compelling idea sparked over 30 years ago.
Still have questions? Contact me!
FREQUENTLY ASKED QUESTIONS