Carol-Ann British Series 67-18H 18 Watt Plexi Head
Carol-Ann British Series 18 Watt Plexi Head - Only 10 available - Very Limited!
A while back we went to Alan Phillips to see if he would be interested in us commissioning him to build a few different Marshall style amplifiers for us. One of the amps we wanted was an 18 Watt Plexi available as a head and a combo. At first, Alan wasn't so keen on the 18 watters. He said of all the ones he played on, they were just so hit and miss. He said some sounded great, but others very bad. If he were to do this for us, he wanted to make absolute sure they sounded absolutely phenomenal.
Alan said he had a friend with the best sounding 18 Watt Plexi combo he'd ever heard. He was generous enough to lend it to Alan in order for him to replicate it tonally. Bear in mind, this is no easy feat. Components have changed a good bit over the years and copying a schematic part for part WILL NOT give you the same results as they did in 1967. Alan had to do a good bit of tweaking to the circuit to get it to sound right.
We had originally suggested the Tremolo circuit be omitted from this amp altogether, but Alan insisted the Trem is a crucial part of what makes this amp sound the way it does. The Tremolo circuit has historically been a bit difficult for amp builders to tame (which is one reason you rarely see highly reputable amp builders offering this amp) but Alan made the proper adjustments in order for it to be stable and reliable.
Construction: All Handmade, all Handwired here in the USA (by a stellar Brit!)
Power: 18 Watts
Power Tubes: 2 x EL84
Preamp Tubes: 3 x 12AX7
Rectifier: EZ81 (New NOS from Late 60's)
Controls: Channel 1: Speed, Intensity, Tone, Volume, Channel 2: Tone, Volume
Switches: On/Off , Standby/On
Dimensions: 26 1/8" W x 8 1/4" D x 9 3/4" H (with feet)
More History of the Carol-Ann British Series (from the Carol-Ann Newsletter):
Recently, Humbucker Music approached me and asked if I was interested building a couple of models that were tonally authentic to some of my favourite amps from back home in England. Given the wide array of awesome British amps from the late 60's, I thought it would be a lot of fun and a change of pace and so chose my own two favorites to base the models off. A '67 JTM50 head with EL34's and GZ34 rectifier and a '67 18W Plexi with Tremolo.
Despite the following and the number of clones out there doing one of these amps 'properly' was a little different, I had serviced and played many over the years back home in England and I certainly remember there were good ones and some not so good ones. After a couple of calls to friends in the business I managed to borrow a 'very special' original '67 18W. I was taken aback how great this amp sounded and found myself lost in it just playing for about an hour. Lovely amount of gain, very thick and harmonically rich, not at all bright and harsh and incredibly tight but bouncy in the low end, even when on full volume. I'll be honest, this was the best 18W I've ever heard.
The goal of this project was to aim for the tones of both these amps, not a 'component for component visual' clone. Theres' also 48 years of improvements on electrical safety and a much much wider selection of components theses days so to restrict onself in such a way would be a backwards step.
Once I had taken the measurements to determine the basic operating points, the amps were pretty much closed up. It's important to let your ears do the listening , not your eyes when you are trying to replicate tones. If you focus too much on the exact values you will end up straying off the tonal path. Tonally replicating a specific amp is way more than just cloning the sum of its parts. That said there were a number of 'stock' component value differences in the 18W to the schematics you find for this model. One of the differences was actually very important and explained why this particular amp sounded so good.....but that little gem stays with me :)
One thing that did become obvious when trying the 18W with different speakers and cabs was that the actually grille cloth used on these combos, the original 'Pinstripe', had a massive bearing on the tone, in a very positive and pleasing way. However, finding that grille cloth was no mean feat. After much searching I found one person on the entire planet that made this cloth and he had gone to the absolute extremes of detail replicating it. The Gentleman's name is Eric Collins (http://bluesbreaker-pinstripe.com) Anyone that knows me, knows that I'm an Engineer and a Guitar Player, I don't live in a world of 'Mojo' and 'Snake Oil'. Thankfully for Eric I had done my own testing and knew there was nothing I could do with the circuit to replicate the frequency specific reflections and attenuation this grille cloth has and it is so critical. Over $200 for a piece of grille cloth for a single one 1x12 may seem a lot of money and it is......but this isn't any grille cloth, its a critical component of the amplifier. Additionally the period correct look is awesome and a very rare sight on any modern amplifier.
With regards to other interesting component ventures. I tried no less than eight different coupling capacitor, types including some of the ones that are sold as specific replicas of the original Philips Mustard Capacitors used in these amps. While all of these Polyester Metal Film Capacitors sounded great, I found one less commonly used type made by CDE that to me nailed the Mustard tone better than the others.
I even went to the extremes of ordering the correct gauge wire and colors from RS Components in the UK...including the infamous 'Pink' wire that is impossible to buy in the US. Getting this wire in my shop was like being reunited with an old friend.
Tube selection took a similar venture to capacitor selection. I found modern ones that best represented the Mullard originals. The only tube I ended up going NOS was the EZ81 rectifier tube for the 18W. I didn't like any of the new production versions of this tube. As with the rest of this project, if it truly needed to be NOS, then it would be.
The cabinets use period correct tolex and fittings and are the exact dimensions of the original.
I did make improvements to the 18W tremolo circuit and the grounding schemes of both models for a lower noise floor than the originals.
All in all this was a fun diversion from my normal amps and I found myself working on this project in leisure time as well as work time. I'm very happy with the final product and I feel anyone who is very familiar with these model would agree I have managed to replicate the tones of these specific great examples of these classic amps with the benefits of lower noise levels and reliability.