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Ohayo from Japan
#1
Adam Smith, proud father of two; one about to graduate high school and the other is not far behind his big brother. 

I am also the proud the owner of two VHT Special 12/20RT amps. What's so special about them (my amps)?

First, they are more affordable than the brand suggests. Before the VHT Specials, I had a Little Lanilei, another very special tube amp with its own unique approach to power scaling designed around a 12AX7 power-amp and an LM386 driving a 6" speaker in a cute cabinet women often mistook for a handbag thanks to the hand embroidered mermaid on the grille. I'd tote that around the greater Tokyo metropolis to rehearsals and gigs where I'd use it like a head to drive a larger cabinet. Eventually I had a friend build me my own full sized cabinet, and we went to a distributor showroom not far from Narita International Airport to audition different Eminence speakers in a cool 4x12 with a selector switch. The amp on top of that cab was a VHT Special 12/20 but there was no way I could afford a VHT amp! 

So I checked the design specs to try and find something similar for less...but there isn't anything like that for less except maybe low-wattage amps also made in China for JET City or ENGL (probably the same factory even!) You don't get a boutique amp from LA for $500...unless it's a Little Lanilei. Like that amp, the VHT Specials have their own solution for "real tube tone at bedroom volume" that sounds compromised.  

So I bought a VHT Special 12/20RT head on the spot because tube driven reverb and tremolo for a few dollars more. Why not!?!?!?
That's another thing that makes this amp special: the reverb driver is a 6V6. This along with the power tubes can be swapped for 6L6GC extending the power (headroom and bandwidth, really) from twelve to twenty watts hence the uncool name of this consumer product.
Unfortunately VHT Specials are inconsistent from one to another. Head #1 is truly special but the non-RT head (#2) I later bought didn't sound as great as the one in the showroom, and stopped working one day because of a loose fuse!

More recently I got a 12/20 combo (#4) for $100 that died shortly after I got it. The 3-watt resistor between B+1 and B+2 eventually burns out in these amps when I play loud through 6L6GC tubes with the amp's internal switch set to HI (20 watts.) That amp is gone now but shortly there after I got a Special 12/20RT combo (#5) that works...for now...

My dream is to use them both in stereo but the power scaling circuit also fails more than one would expect a properly built amp to fail...but of course these amps were probably built by Chinese country girls (not like the detail-oriented Japanese women working at the Roland factories) after being muntzed by the Germans (AXL) who bought the VHT brand, and then tried to turn it into Bayringer. 

When the WATTS controlled failed a SECOND time, I had already bookmarked London Power. Unfortunately modding/repairing the Special 12/20RT is not as easy as the ad copy suggests because of the reverb+tremolo daughter board mounted directly over the parts that most often need replacing! Big gobs of solder take forever to melt. The wiring looks like someone in the factory thought it would be cute to throw a party for the mice before turning on the power to electrocute them. Still I love these amps. Find me another tube amp that can drive a 2Ω load.

Love is circuit where commitment to something produces positive vibes. That's why I dropped another $100 on an SV2+VCK for this amp! 
Of course I would love to have a Carr amp (and a more powerful amp for my car, too) but my son wants a $1000 camera for graduation...
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#2
Howdy, and welcome!

I have a friend who owns the VHT Ultra Special 6, or whatever it's called, also with the WATTS control. I'll be following your adventures with interest to see if I can preemptively help my friend out in any way. Good luck!
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A warm welcome to tube amp modding fans and those interested in hi-fi audio! Readers of Kevin O'Connor's The Ultimate Tone (TUT) book series form a part of our population. Kevin O'Connor is the creator of the popular Power Scaling methodology for amplifiers.
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