VHT Special 6 – modded

At the end of last summer I splashed out and treated myself on a new amp, my very first ‘new’ amp!

I was on the look out for a small tube amp that would suit my needs – i.e. plodding away in the front room, and not for gigging. The VHT Special 6 kept popping up with very favourable reviews, so I bit the bullet and went for it. I opted for the head and cab version.

This is a great little amp, straight out of the box, hand-wired, with a  12AX7 preamp tube and a 6V6 output tube. There is a boost feature, which is footswitchable, although the huge jump in volume isn’t the most practical. It can get pretty loud when pushed, in a home-practice context. There is also a half power option for late night playing.

Simple controls – one tone pot and volume pot. Hi and Lo inputs, and on the back three speaker outputs for 4,8 and 16 Ohm respectively.

The cab is a closed-back 16 ohm with a VHT Chrome-Back speaker.

The finish on both the head and cab are top notch.

One of the attractions of the amp is the ease of access to the hand-wired board, which makes it ideal for modding. Heck, they even say it on their website:

“The mod-friendly Special 6 is easy to customize for home amp builders and tube amp enthusiasts.”

VHT seem to be actively encouraging mods with this range of amps, so I thought it would be rude not to.

2012-10-27 19.18.46

VHT Special 6 internal shot.

As this was my first AMP mod, and first experience with tubes I decided to get some expert guidance, so I got myself a mod kit from Alnico Magnet

Here’s a description of the mod kit, taken from the Alnico Magnet website:

“The stock Special 6 circuit is loosely based on the classic Fender AA764
(mid-sixties Blackface) circuit, (also used in the Champion 600), but biases
the preamp tube to sound dirtier. In place of the Blackface Champ’s Bass and
Treble controls is a fixed value tonestack network. My mods keep the typical
Fender mid-scoop sound, but bring more clarity and less preamp distortion. I
also remove the “LO” input jack, and change the control layout to give separate
Bass, Treble, and Volume controls as per the original Blackface Champ.”

I cannot recommend this kit highly enough. High quality components, a very detailed 19 page instruction manual, and 50 or so photos detailing every step.

Each of the mods were broken down separately as well so you could pick and choose which ones to do if, for example you decided not to do certain ones.

Perhaps not for the complete novice, but for me, with a good understanding of electronics, and competent soldering skills it was a great introduction into the world of valve amps.

2012-10-28 21.27.35

Modded VHT Special 6

The above picture is an after shot, with most mods in place, just the Negative Feedback mod to be installed.

As you can see on the board a lot of the components have been upgraded, with Orange  caps replacing the original.

Also there has been a Bass knob added, so instead of the original (black knobs) Tone, Volume and hi/lo inputs the modded version has Bass, Tone, Volume and one input. I could have kept the lo input as well, but I don’t really have a use for it.

All the original pots were upgraded, and the push/pull volume pot, used to engage the boost was replaced by a standard pot. Instead the Boost option is engaged by a switch next to the boost pedal input.

2012-10-28 21.28.21

Back of head, showing boost switch next to foot switch input.

While I was at it I changed the stock 6V6 output tube. Instead of a straight swap for a known-brand 6V6 I took the opportunity to re-bias and fit a 6L6 in it’s place. These tubes mean that there’s a little more clean headroom in the amp as they don’t break up as early as the 6V6. I don’t often get the opportunity to crank this amp to the max, so I was more concerned with getting a good clean tone out of it. A tube screamer in front adds my overdrive when desired.

The pre-amp tube I changed to a JJ/Tesla ECC83S

2012-10-29 10.20.25

2012-10-29 10.20.19

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2 Responses to VHT Special 6 – modded

  1. russellwriter says:

    Reblogged this on Rob Russell Music and commented:
    Hmmm … An amp project might be cool?!

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