Amps: VHT Special 6 Ultra - in depth

Introduction

Note: this entry was already published in my old Spanish version of this blog, around April / 2011. Just revisiting it here. I sold this amp because I need the money to buy other gear but, the new 22W version is in my list.

To be honest, classic or vintage tones had been already covered with my current amps. Maybe, I would need to cover Hi-Gain tones.
So... why that VHT Special  6 Ultra?.

Several reasons here.

Incredible affordable. The cheaper one is the Special 6 combo, that costs just 135 Eur!, and it sounds fantastic. The expensiver one in the line is the Special 6 Ultra head + 1x12 closed cab, doubling the price of the previous one but, this means just 265 Eur!!!. For a tube amp!!!.

What do we get in the whole line Special 6?.
A class A, single-ended amp, point-to-point handwired.
Yes, yes, yes. I am hearing you claiming: "it's Made in China".
Aaaaaaand?. Open your mobile, open your PC, your TV, your MP3, your...

Special 6 series have amps delivery a max of  6W RMS of pure tube sound, thanks to its own 6V6GT power tube. Simple signal path, without IC or transistors.
That's something I was looking forward: a cheap kit that I can use as a base to experiment with different components.
Special 6 series allow you to easily substitute any component with others of higher quality, since everything is visible mounted on an eyelet card. To increase the fun, Special 6 diagram is available in VHT' site and, you can freely download it, if you need to decide to enhance it or just to learn about the amp itself.
More interesting, the own designed point to several mods that you can easily do to change the amp character.

Having a Vox Night Train, from the tonal point of view... do I need a VHT Special 6 Ultra?.
Really not. The NT is somewhat similar, having a simple design but with a different voice (mounts EL84s instead of 6V6GT) and, with double the power of the VHT. NT's transformers are way bigger (responsible for the 80% of the weight of the cab), it's way more portable and takes way less room.

My point is that this amp is really interesting to have some kind of boutique kit (except for quality of components) that you can enhance to your needs, substituting components, step by step.

Any quality kit that you will find in the market, will force you to build everything and, will have a price above any regular production amp. I am seen that VHT as an already mounted kit, which components can be enhanced when needed. But, it sound really nice as it comes.


Differences between Special 6 and Special 6 Ultra

There are some differences between the Special 6 and the Special 6 Ultra:

• Ultra Channel. Version Ultra has two input jacks. First one if for clean channel, while the second is for Ultra channel. Ultra channel stacks one more triode in the cascade gain.
• Ultra Channel Gain. Ultra channel has a dedicated gain control.
• Texture Switch. This 3-way switch gives three different foundational voices to the amp. Position I sounds closer to Marshall, position II sounds closer to Bassman and, the center position is the mos even.
• Depth Switch.  This switch has 11 different positions, that equalize differently the voice. Overall, in the extreme left hand we got the most natural sound of this amp, with more bite and brightness. While rotating the switch to rigth hand, we are removing high end, darkening the tone and increasing bass content and tube' saturation.
• Power selector. This is not a dummy-load attenuator!. In principle, it reduces the voltage to which the Power Tube works, which decreases the output power of the tube and, therefore the final power delivered to the speaker. You notice a rela drop in power beginning at 12:00.
• Line out. Ultra version has a Line-Out post-preamp output, that allows you to send the preamplified sound to whichever mixing desk or audio card.
• Tube-driven Effects Loop. Ultra version counts with a tube-driven FX Loop. This loop is being fed by the preamp and, has not adjustable volume. The signal level depends on the actual gain level of the preamp section, what can make to clip to those pedals inside the FX Loop.

Common characteristics

Both share a basis design, class A single-ended powered with a 6V6G power tube.
Since the design is cathode-biased, you can substitute such a tube with any other octal power tube: 5881, EL34, 6L6, etc.

But, be careful!. The OT is designed for 6V6GT tubes and, the maker recommends to switch off the amp after 1 hour if you load a more powerful tube.

Also, when going to high power tubes, you should substitute the fast-blow fuse with an slow-blow fuse, since the stock fuse will not support the high starting peaks of tubes like the EL34 (note: this is already fixed for currently produced units).

Main goal of the designer was to make an point-to-point handwired amp that could be available at a maximum of 200 USD.
And... they succeed!!!.

But, to achieve this price implies to takes some design decisions to make the price to be the targeted one.
Sure, Chinese labor cost is the first decision but, there are some other compromise solutions inside.

The amp has the typical Tone Stack considered in the circuit but, you will never see their related variable control pot. Instead of those pots, each "tone setting" is being fixed with a substituting resistance with the value that delivers the tone that the designed wanted for this amp.
One of your projects could be to substitute those resistances with 3 pots, to have full control over amp's EQ.

The Boost mode works in a similar was as the mode Thick of the Nigth Train. That is, when you switch on the Boost mode, the signal bypasses the Tone Array and delivers a purest signal, with a clear increase of the output loudness.

Differently from the NT, we have a global tone knob, at the end that allows us to "fine tune" that "pure tube" sound achieved with the boost mode.
This is a smarter approach than the one of the NT.

The General Tone is very efficient and, helps to radically re-EQ the amp, with a broad range that can go from deep a-la-Bassman tones to sparking a-la-vox or a-la-Fender tones, with nuances enough in between.

The amp doesn't seem to need for any booster to raise the guitar' signal. The guitar sounds full bodied.
It seems that humbuckers can saturate in a bad way this amp so, it works better with single coils.

Dynamics are excellent. You can easily control the sweet spot with the strength of your picking and, the sound cleans very well when rolling off guitar's volume. It sounds very organic and dynamic.

Overall, I have the impression that this amp has more floor noise than other amps. Maybe the Chinese tubes that came stock are responsible for that (will check).

About tone, the sound is full, rich and round. It has power enough. Its 6W RMS sound more or less as the NT at 70% or the Marshall 50W at 30% and, therefore, they allow you to krank the amp and get the best of the tubes, at way lower volumes.
But, don't be fulled, even 1W is over the bedroom level (but, for that, we have the Power selector!!!).

The switch High power / Standby / Low power, changes the power amp regimen to Pentode (High) or Triode (Low). Analogically to the Night Train (among other amps), this change of mode means around 50% of drop in loudness but, also, a change in the character of the sound, that goes mellower and warmer.
While the Pentode mode is brigth and powerful, the Triode mode delivers a sound full of smooth nuances, a very silky tone.

Special things in the Ultra

Ultra channel works nice with a reasonable gain level (up to 2:00), beyond that, the excess of gain adds lot of grain to the sound, producing a sonic wall too thick and producing excessive feedback.
This channel makes the sound darker, bassier and compressed.
The achieved loudness with Volume And Ultra controls at max is impressive (what a 6W !).
For settings on noon, it delivers a nice crunch, very rocker.

The broad range of tonal nuances that offer the different combinations of controls Depth, Texture and Tone are huge. From very bassy and dark to trebly and sparkly and even piercing. Those tone-shapers together with Volume and Gain controls offer to you lots of possibilities and, I don't believe that one cannot find a single setting where this amp will be of use.

The Power Selector helps to maintain lower loudness level but, the sound quality drops, since there is no power enough to move the speaker's cone with authority. But, at least, it can be used at dorm levels, with some lack of mojo, but usable.

In my opinion, both channel are good enough to work and, a pedalboard can help to achieve a broader array of sounds. Clean channel is a nice platform for a pedalboard.


Conclusions

For anyone bored of his/her solid state amp that wanted to start his/her adventure with tube amps, without expending a bunch of money, I highly recommend this amp.

As the NT started a new generation of small, highly transportable, affordable and nicely sounding small amps, I consider that this VHT Special 6 models will create a trend of affordable point-to-point handwired amps.
Designer's goals were absolutely achieved.

For those already having some nicely voiced high transportable amp, as the NT, there is no need to purchase this amp.

But, at least, you can krank the volume to max in this amp, something that you cannot do with the NT, before get some ear's pain.

Respect of weight, the head weights way less than the NT head but, the cab weights more, instead. More or less same weight putting all together.

Respect of size, the VHT is way bigger than the NT. The head is more or less double the size of the NT head. The cab of the VHT is bigger than a Koch Studiotone Combo. Huge for just 6W.

For those dreaming on to build his own amp or, those interested in to learn how to modify yor amp, VHT makes it easier for you, with all its components clearly laying over an eyelet card. Even if we finally destroy that amp, we would loose 135 Eur (Special 6 combo).

As it comes stock, I like the sound enough. It can only be enhanced with high quality components.
Well, I will swap the Chinese tubes with higher quality ones.

I am very curious to know which will be the impact in market of this series. Will we have an affordable Hiwatt Class A at this price level?.

Videos

Following videos are a detailed and deep exploration of the possibilities of the VHT Special 6 Ultra.
To compare how the tone changes with different settings, I am using repetitively same riff, what can be boring.

Part 1

In this part, I am introducing the amp, reviewing finishing, controls and connexions. I am giving the reason why did I bought it and, I make a size comparison against other amps.





Part 2

Clean channel, range of volume and boost mode. Power selector.






Part 3

Clean channel. Range of Tone Control, Texture control and combinations between both.




Part 4

Clean Channel, Depth control and, its combinations with Texture control We check the more extreme sounds, the darkest and the brightest, to understand the broad range covered by this amp.





Part 5

Checking Triode mode in clean channel, then we review the Ultra Channel.




Part 6

Checking how it cleans when rolling off guitar's volume and, amp's dynamics. We talk about the excessive floor noise and, end of demo improvising a blues over a backing track.