Read the full article
This article was originally published in issue #34
To read the article in its entirety, view the digital magazine
Ashdown's custom shop is based in the UK and it seems offers an array of handbuilt and often innovative amplifier designs to suit just about every taste and need. The range runs from amps like the new Retroglide-800 'D Class' amplifier featuring an 800 Watt power amplifier and 12 band graphic equaliser, to the big beefy BTA 400 all valve/tube 400 Watt head that is guaranteed to quake your boots with luscious bass tone. But that's not all. Hats off to Ashdown for listening to its customers and offering up something a little different from the main product line. An all valve 15 Watt bass head? Known as the CTM-15, I really wouldn't mind having one of those in my practice room!
Filling the gap between the CTM-15 and the big BTA are four – yes, four high spec 'Classic Tube Magnifier' valve heads. There is too much to explain in detail here, but the choices include a pair of 30 Watt valve heads, a 300 Watt valve head and the fine 100W that we are pleased to see in for review. Naturally, we were going to need to hear it shake the rafters a bit, so it was only natural that Ashdown would send us a big cabinet in the form of the CL-610, also from the custom shop.
The CTM-100's signal path is all valve - even the D.I and effects loop are driven by valves - so even if you are taking an audio feed from the D.I or effects loop send, there's nothing but valve tone being fed. Choose your instrument input and away you go: high and low inputs tackle any input gain issues you have from low or high output instruments. The 'low' input is for instruments with a low output. What is also interesting is that the inputs are also impedance matching. This is important, more so for passive basses, and put simply, helps to ensure you get the best tone from your instrument to the signal path under that cool exterior.
When it comes to tonal options, well there's quite a lot to get through! The first thing I should mention though, is that the EQ knobs and related push buttons are all fairly interactive due to the use of passive circuitry. The 'mellow' button for example essentially reconfigures the EQ curve on each of the controls, giving you a smoother bass sound with less aggressive top end and to me what sounds like a resultant boost in the low mids. With it engaged, all of the controls react differently – so it is not just a narrow mid boost. This is something to take in to consideration when trying out this amplifier. Similarly, the Deep and Mid shift controls actually seem to change the range of adjustment in the Bass and Middle controls too. Again, being passive, the tone controls are more subtle than say that of the EVO heads with active boost and cut across a 'graphic equaliser'. Some will love this, others will prefer more dramatic tonal changes. The inherent tone of the valve head is there to stay though and it is good. Deep and rounded and almost bell like in the chime of my low notes.
A bright switch provides top end boost and this was very useful when playing in to the provided CL-610 bass cabinet that does not feature a tweeter. There's a nice enhance there for slap playing and also adding bite when using a plectrum. Ah, I can see it now - P Bass slung low, plectrum in hand and a stack like this being pushed hard! The CTM-100 will take it too. There's dirt available from the pre-amp section and careful tailoring of the controls will reward you with an aggressive edge up to a gritty distortion. What will please your audience though, is that this head will 'break up' at a more reasonable volume than say that of the BTA 400!
There are some really nice additions to the basic bass head format, for example a mute switch, the previously mentioned valve driven D.I, effects loop and of course the now famous Ashdown power gauge that provides a visual indication of your actual output level from the amplifier. There is more though as I mention in the video. Flick the Audio/BIAS switch and the head allows you to be the technician too. Those used to taking valve amplifiers to be 'biased' after installing new power amp valves often are expected to pay for the service - well, with the CTM, switching to BIAS mode allows you to do the technical stuff yourself (refer to the manual first!) and the meter on the front will give you a very accurate reading so that you can set your amplifier up correctly! This is clever and thoughtful.
Round the back of the amplifier there are the usual connections for mains power and a set of connections for your speakers. Again, refer to the manual as it is very important that you connect the correct value load to a valve amplifier. Sockets for 2, 4 and 8 ohm loads are catered for.
Power and standby switches are round the back too, out of the way of the front panel. Unless you are in a tight space on stage, I suspect you'll be able to get round and reach these when the CTM is sat on a cabinet. Well, unless it's a tall cabinet on a dark stage!
Talking about cabinets leads us to the CL-610, one of many models available from Ashdown. This Eminence custom speaker loaded brute handles 1200W RMS and is made from Birch Ply. It features a tilt back design with wheels on the back edge (with a grab handles) to make manoeuvring easy. Well... easier! There are kick plates to protect the finish when you give it the boot over to the wheels and slide rails protecting the finish when it comes to loading the band van.
The CL is a substantial cabinet and weighs in at 42Kg and is rated at 4 Ohms. Plenty of 'oomph' there as this could satisfy your one cab solution requirements.
Paired together, the tones were 'classic' and vintage with lots of mid presence and surprisingly a lot of volume when rated at 100W output from the amplifier. I'd have loved to have placed the head on to a 'hi fi' or 'monitoring' style cabinet too as I am sure that the head is capable of dialling up some sweet top end clarity - certainly taking a DI feed off to our in-house monitors showed up some top end richness. So don't expect this to be a two dimensional amplifier head that does one thing only. It will please hi-fi listeners too.
If a traditional handbuilt valve head is your dream bass amp, this has to be the place to start. It’s got all the extras you could ask for, it’s built like a tank and it produces a huge amount of surprisingly versatile volume. The only downside might be getting used to the way passive EQ means your tone controls interact with one another - but anyone who has used vintage valve/tube gear will have experienced that. Consider it part of the charm! There's no doubt this is a cracking combination from a bass specialist who can still show most others a clean pair of heels.