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What is a "Tube Cube" Tube Amp Attenuator?

An Attenuator is a device that is inserted into the high power signal path, between amplifier output and speaker cabinet input to act as a "load" and a volume reducer, with the idea that you want to run your big power tubes hard, very high output, into the overdrive zone, then using the Cube's Volume control to reduce the speaker level.

The Tube Cube works equally well with Guitar amps, or Bass amps and is 5 inches by 4 inches by 4.5 inches tall, weighs about 2.5 lbs.

It must "act" like a speaker with appropriate impedance so the amplifier is happy, and it must pass signal and allow for adjustment of sound pressure levels at the speaker.

You may also use the Cube as a cabinet impedance matcher.  Say you have a 4 ohm amp but an 16 ohm cabinet you want to use, just hook the Cube up, set the switch to 4 ohms, plug in your cabinet and have a blast.

A portion of the power that leaves the amplifier tubes is "used up" inside the attenuator circuit, and the remainder is passed on to the speaker cabinet.

The position of the volume control on the attenuator determines just how much power is "used up" and how much is passed to the speaker.  On the Tube Cube, turning the control clockwise (CW) makes the sound grow louder.

It does NOT go in the effects loop, the send-return path or any other place, it goes between the amplifier and the speaker, end of story,

oh, and it doesn't have a 9 volt battery in it!! (be very very scared of 9 volt battery tube attenuators!!).

Unlike transistors, Vacuum Tubes exhibit a warm bluesy type of sound when driven hard into the region of distortion.

This is a highly desirable sound and one that is easily achieved by turning the volume control on the Tube amplifier to maximum.....  Simple.

The problem is while you get this nice bluesy crunchy type of sound, it is WAY too loud.   The cats and dogs run away, your family runs away, the neighbors call the cops on you...

I don't know if you noticed, but 40 watts of tube power is just a huge amount of SOUND.  To me, it compares more closely to at least 100-200 watts of transistor power.  My 40x12 watt Fender Blues Deluxe puts out more "sound" than some 120 watt big name tranny heads feeding a 4x12 cabinet.  If you don't believe this, then you probably don't have a tube amp yet!  :-)

Enter the "Attenuator", its only purpose* is to allow your tube amp to play loud and crunchy, but dispose of some of that volume/power  before the speaker gets to blow your eardrums with it.....

*Cube as an impedance matcher, ....  Have an amp that needs 4 ohms, but only have an 8 ohm cabinet?  Or an amp that needs 8 ohms, but you have a 4 ohm cabinet (or want to hook up 2 cabinets)....Great, use the Cube as a impedance matching box...plug it in and turn it all the way up, connect up your cabinets..all of them if you want,  and forget it.

One customer contacted me after getting his Cube hooked up and said,...and I'm not making this up,...  "When I turn my amp up all the way, the sound is distorted." ...  uhmm....ya... I understand.. better send that Cube back right away!

Another customer wanted to used it WITH his MarshL power brake, Why ???  I couldn't figure this one out at all, but he didn't like the sound quality of the MarshL power brake and thought adding a Cube attenuator inline with it would "fix" things...    Nope.. 
I think he said "sounds broken  and clipped unless used alone"     .....The Cube wont fix a bad sounding setup...  The Cube makes the sound smaller and passes it through otherwise untouched.   Please use it "alone"  :-)

If it isn't obvious already,    Here it is again...........  An Attenuator is used to allow your amp to create a distorted sound by driving the power tubes hard, while reducing the volume level of that distorted sound from your speaker.  The Distortion is beautiful, obvious, and desired!  It is the whole idea behind this whole Idea!   got it?    Good!

 

There are many good choices of attenuators available, generally, they are quite expensive, usually $299 to $699 and more.

 Tone is a big feature and one that is highly subjective.

10 people will hear 10 different things, when listening to the exact same sound.

Tone is created in your environment by your source, ie, Guitar, your amp and amp tone settings of course, but other things affect the sound also like the:

1. "volume" of sound bouncing around inside the speaker cabinet and off the speaker cone.

2. "volume" of sound waves actually make the tube vibrate internally, which changes the tone.  (take a 50 foot speaker cable and move your head in to the other room from the cabinet...it WILL sound different!)

3. "volume" of sound bouncing around inside the room, off objects nearby.

4. The amps style of rectifier and design, which can affect the sound when operating at high volumes due to current sag.

 5. Different Tubes behave differently when overdriven, some flatten out on the bottom end, and some flatten out on the top end, don't be afraid to move your tone controls around to get the exact sound you seek.

6. Note, some amps sound better than others when cranked up, for the slackers, work with em to experiment as long as it takes to get the great tone you seek.

What happens to this tonality when you introduce an attenuator into your speaker path and lower the volume?...

Lower volume coming from the speaker cone, causes different interactions between cone & cabinet and you hear a different tone.....

Less Volume causes less vibrations within the tubes, causing a different tone to be heard.....

Less Volume causes a different tonal relationship to be heard in the environment you are playing in.....

Playing the amp at max power, accentuates the rectifier sag. It is a design feature, not a defect but is much more apparent at max amp output and lower volumes.....

Because the LOUD earsplitting sound is now much smaller, and you can detect much more in the way of subtle differences in the sound

Remember, you still  have tone controls on your axe as well as your amp..dont be afraid to adjust things to make the sound perfect.

If your amp sounds sweet when cranked, you will like what you hear, if your amp sounds raspy/ugly when cranked..well, an Attenuator will not help matters! (but it will be quieter!)

The exact same sound played at a lower (or higher) level will sound different to your ear.  The ear is non linear and this is why "Loudness" buttons were invented on audio amps.  At lower volumes, the circuit boosts the low frequency's alot more.  To your ear this is normal and sounds better, but it is "different"  or non-transparent, than the actual source.

So, in summary, tonality is quite difficult to explain and measure, it remains one of the most frequently asked questions to me, and one that is the most difficult to explain and predict.

In the reviews.harmony-central link near the bottom, you will find this statement.

"I've changed my setup so much because of the Tube Cube that I really can't comment on it's transparency other than to say that I reckon I've found the express lift to tone heaven. If it colours my tone, so be it, the results are amazing!"

 

WILL AN ATTENUATOR HARM MY AMP OR WEAR OUT MY TUBES?

A better question is "will a well built attenuator harm my amp......"

Guess what? Tubes are light light bulbs, when they are on, they are getting slightly older..yep, its true, using your tube amp will wear out your tubes. If you run your amp at max volume, the tubes will wear out a little bit faster. That is one advantage to transistors I guess. The good thing is Tubes wear out very very slowly, I have a 1995 Blues Deluxe with original Tubes, and a Ephiphone Junior that is only 2 months old, with new JJ's installed, (my choice) .....

My advice...find your great tone you seek and fergeddaboudit..don't worry about the Tube replacements every few years or longer even.

Using an attenuator will not wear the tubes out any faster than the same volume or usage patterns without an attenuator.

Same goes for output transformers, driving a speaker or attenuator really makes no difference to the transformer.  But if you run the transformer at maximum power forever, it will probably not last as long as the same transformer run at 50 percent power.

Years ago, I laid my amp over on it's face to simulate an attenuator...   Dont do this   :-)

The difference..at least for me, is I am more tempted to crank my amp max with the Tube Cube each time I practice, because the sound is just so very fine.....

By the way, if you have weak tubes or other components on the verge of failure, cranking your amp to max and playing it for hours will probably not end well...Into a speaker or Attenuator..no difference!!  

Keep in mind that most people never operate their amps at the boundary of high power output.  When an attenuator gets involved, maxing out your amp creates more risk of course.  Also, some amplifiers are not designed well enough to  be running at the ragged edge of the power limit.  If only there were a list somewhere of weak amps.. :-)

Not a weak amp by any means, but I have a recent customer with a brand new amp, 3 letters, begins with E and ends with H, and he said it sounded pretty ugly, bad tone, flat and lifeless, when playing into the Attenuator.
He tested his Cube by trading with a friends Cube and had same results...both sounded great in the friends Marshall and no good in the E  blank H amp.  I have no experience with this particular amp, but might want to proceed cautiously if you own one and are considering an attenuator.

 One more thing, after connecting your attenuator, suggest turning on your head LOW and carefully, (Cube full up-CW, and amp to 1 or Low),
Then listen for a small but correct sound....to assure that you connected everything in the proper fashion. 
Each time you turn it on, best to check in this same fashion, in case someone else messed around with your setup and got it hooked up backwards.

If you hit the power button and crank the volume to max, and the for some reason, you are not connected correctly....your amp will not be happy. 
Pay careful attention to the proper connection methods,   amp to attenuator input, then attenuator output jack goes to your speaker or cabinet.
A word of WARNING, Getting this part wrong will not end well.

On the subject of Phony Attenuators:

If you see a product that claims to be an attenuator, but is just too low priced (10-60 bucks), its probably a "low level" signal attenuator.  Sometimes known as a  volume control box, or effects loop attenuator or tone booster.  They will not indicate a power rating, because they do not absorb "watts".

These are to be avoided if your goal is to drive your tube amp's output tubes to maximum power output and sweet tube distortion.

Sometimes called a Loop signal attenuator, works with the 'effects loop'..... These low level things operate by turning down the INPUT signal to the amp, similar to turning down the volume control on your guitar or bass. Doing this causes the amp input signal to be reduced, which reduces the output of the power tubes, which lowers the volume, AND and the distortion disappears as a result.....  The little bit of pre-amp distortion this creates is pretty ugly..

Oh, most guitars and basses come with one of these..it's call a VOLUME CONTROL!!  (It's the same thing, just in a different place in the circuit)

If you're going this route, probably much better sounding to use a screamer or a DS1 box instead, and maybe a transistor amp.  :-) 

Since you are here reading this, you know what you need, So save your money   :-)

Also, beware of phony Tube Cubes out there seen lately for sale..amazing isn't it?

Summary,

Does the world need yet another $500 attenuator..I think not.  The Cube is simple, reliable and sounds great, it's also very affordable.

You can get into one for just under $120, This was my goal.  I spent a lot of years doing without, or borrowing a friends brake, this is why I worked to create this  little Cube.

Reliable, it is designed to be reliable.  The 80 watt model is not running at the ragged edge when consuming 80 watts.  Same for the 160 watt model.

Works equally well with Bass Guitars.

And yes, you may run your 5 watt Epi Jr, or any other low power amp into the 80 or the 160 watt models, just make sure you can play into the appropriate impedance.

Tube Cube: My Tube Cube attenuator uses a impedance matched module that passes signal in a "flat" or very transparent method from input to output

It is designed to have minimal tonality change taking place during this signal transfer through the device.

It is considered an audiophile quality device that is both resistive and reactive combined..exactly as a speaker is.  Said another way, this attenuator is not just a big resistor ladder network like a few of them on the market are.

It will put off a little bit of heat if driven hard for a long period of time, but is designed for continuous operation at maximum power rating without failure.

It is designed to operate transparently tone wise (flat)  from 20hz to 20,000hz, which makes it perfect for both Guitar AND Bass amplifiers.

Lastly, it requires no grid AC 120volt power, it is self contained and is completely powered by the amplifier output.

The connection scheme using standard 1/4 plugs is the following:   AMP to Cube INput , Cube OUTput to Speaker.  Included with your Tube Cube is a 3 foot long speaker cable, each end is fitted with standard 1/4 plugs.

Remember that the Tube Cube has multiple impedance settings.  This factor alone is pretty important, especially if you have more than 1 amp and want to use it between them.   Many of the other attenuators available are for a single impedance only, and you must specify what you want at the time of purchase.  Later if you buy a new amp with different requirements..kiss your attenuator goodbye, or sell it on Ebay :-)

I get this question alot...  "Do I need to double the rating of my amp head, when I consider which power rating attenuator to buy,  In other words, will my 50 watt amp require a 100 watt attuenuator?"  A:  For some attenuator brands, yes, but Not for the Cube, it is very conservatively rated and the 80 watt Cube will handle an 80 watt head without concern, Same for the 160 Cube matching up to a 160 watt head.    Keep in mind that if you have modified or hot-rodded your 80 watt head and it puts out more than standard rated power, then obviously yes, you need to consider this extra power, as your 80 watt head isn't really an 80 watt head any longer :-)

Also, if you have a 120 watt twin and pulled 2 of the output tubes, now you are down around 60 watts...go ahead and get an 80..no problem,

One more thing, I ship FAST,  "After you pay, it is on the way." usually the next morning, often sooner.  :-)

The Tube Cube comes in 5 different configurations to meet your needs:

"Pro160" model:

160 watt single channel, double output, With a Line out jack.  (adjustable 8ohm 12ohm 16ohm and 20ohm)
Plus RCA low level output (sometimes called a Send or Line Out) for recording or driving another amp, ** or mixing console, LED signal indicator, Carry Handle.   Also note, you may use a single output or both of them interchangeably.
** Yes, you could use the line out jack to drive a 2nd transistor amp, enjoying some of the benefits of cranked tube tone,    :-)

With the Pro 160, you can record yourself into a digital, reel to reel or any kind of recorder that uses an RCA jack.  
Line out Specs. 30db attenuation, 33k input load, 1k output load, 20-20k flat response.


Deluxe160 model, & BassDeluxe160, (exactly the same)  
160 watt single channel double output, (adjustable 8ohm, 12ohm, 16ohm and 20ohm), new style enclosure with carry handle, Large Knob. 
(same exact product, with 2 names), for Ebay listing purposes to reduce the questions from bass players asking if I have a "bass model"  :-)


"Basic80" Model,
80 watt single channel, single output,  4ohms, 8ohms  adjustable.
The most affordable in the newest line is the "Basic80", Single input, Single output, 4,8 ohms adjustable, new style enclosure with carry handle.

"Stereo80" Model,
2 input channels, 80 watt  each channel has a single input single output,  Single knob, 4ohms, 8ohms adjustable.


You can find these in my ebay store at   http://stores.ebay.com/vspeeds    Also, at auction occasionally for a small discounted price.

I have been asked about using an attenuator for a pure transistor amp...

 I have always resisted selling my product to transistor customers...after considerable thought, maybe I have been too hasty....

The simple answer is that, in my humble opinion, transistors sound horrible when driven into distortion, also, the hostile signal shape they produce (square) can damage your speakers.  If you want to produce this transistor distorted sound for some reason, and have it play at a lower volume to protect your speakers, then, an attenuator will do just exactly that for you, go ahead and buy one.

Want to make your monster transistor ampstack sound like a tube amp?   
Get yourself  a $99 Epiphone Junior tube amp (sweet sweet amp for the money), hide it down behind the monster tranny stack,  and hook up the Pro160 to the Epi, and connect the line out to your Monster Transistor amp head input.  ..yep!..it works.., real tube crunch from a monster tranny stack :-)

Questions of interest:

Q:  Hi, technical i'm close to zero, therefore next question: What is the effect or better said the advantage of your powersoak when the chain is guitar/effex/input-amp.I hope your answer is what i'm looking for. thanks,

A: Thanks for asking, It is another tool in the toolbox..some of the efx are pretty good, but none come close to emulating a true tube-in-overdrive condition. A couple good reasons to use my attenuator, first, you can run multiple cabs without hurting your amp. secondly, if you work at it some, you may find that sweet tube overdrive sound and be able to control the volume from the speaker while maintaining the perfect overdrive condition. Some musicians are happy with a tube screamer or a Boss DS1 for their distortion sound. With these, you sound like every other player using them...and then there are those that just keep on looking for the perfect sound, these folks will cross paths with an attenuator sooner or later, mine or someone elses. :-) regards JS

I get this question alot, so it's here twice!...  "Do I need to double the rating for my amp head, when I consider which power rating attenuator to buy,  In other words, will my 50 watt amp require a 100 watt attuenuator?"  A:  For some attenuator brands, yes, but Not for the Cube, it is very conservatively rated and the 80 watt Cube will handle an 80 watt head without concern, Same for the 160 Cube matching up to a 160 watt head.    Keep in mind that if you have modified or hot-rodded your 80 watt head and it puts out more than standard rated power, then obviously yes, you need to consider this extra power, as your 80 watt head is'nt really an 80 watt head any longer :-)

http://reviews.harmony-central.com/reviews/Effects/product/Jim+Sanders/Tube+Cube+160w+Dual+Output+-+Tube+Amp+Attenuator/10/1

          My guide exceeded Ebay max length sorry, See part 2 for additional information, customer comments and feedback. http://reviews.ebay.com/Tube-Amp-Attenuator-Tube-Cube-Part-2_W0QQugidZ10000000004693696

Click below for guide part 2
Guide Part 2


Thanks for reading my guide part 1. If you found it useful, please click on the yes button just below..thanks!

Of course all of this is my personal opinion based on my life experiences as well as my professional experience, thanks for stopping by.... Kind Regards...Jim Sanders