After 20 years in the bass amp business, EBS launches another debutante. Meet the first ever all-valve EBS amp, the Classic T90.
One could name the T90 a world news item. EBS of Sweden, now a global brand known for its quality products, has now completed its product line by moving from all-transistor amps via hybrids and to the T90, the manufacturer’s first all-valve amp – not a transistor in view. Having in mind their innovative and user friendly previous products and my fondness for valve amps, my expectations were high.
DESIGN
The aim of the T90, according to EBS, was to build a high quality, all-valve bass amp for studio use and smaller stages with a reasonable price tag. When developing it, EBS has employed designers with experience from guitar and hifi valve amps and major efforts have been made to use quality components, some of which were specially developed.
As proven by the photo, the exterior design lends from old valve amp classics. It is a practical design in regards to the need to cool the valves, but the glow of them also enhances the look of it.
If one looks through the ventilation grid, one can see to the left the huge specially designed output transformer, which is an important part of the sound. According to EBS, it is over-dimensioned in order to deliver to the max regardless of strain or time. To its right are four smaller valves. There are two separate inputs for passive or active basses and the preamp is driven by a 7025 valve (a low noise version of the 12AX7/ECC83) which also drives the passive filters with bass and treble controls. The filter part is designed to work as a boost/cut filter. Normally such filters have a feedback return, which EBS excluded in order to enhance quality. The entire preamp is designed as a Class A unit, which to many is thought of as better than other designs but also less energy efficient – an aspect that may not be of high importance when choosing an amp.
The Presence control is not part of the filter stage, it is located in the feedback circuit ahead of the power amp so that it can affect the distortion character of the power amp. The choice of power valves stood between 6550 and KT88, both common in bass amps. Both transmit bass well, but EBS chose the 6550 because of its more focused and tighter low end. On the back of the amp are 4 ohm and 8 ohm outputs, both with Speakon connectors. They cannot be used in parallel, though, and using a load beneath the one chosen with the output may damage the amp. Keep in mind that stacked cabinets often are run in parallel, which gives lower total impedance.
Just to make us valve freaks even happier, the balance XLR output, too, is valve-driven. There is an earth lift switch but no pre/post filter selector. Apart from that there is only the power connection and a few contacts used for biasing the valves. Upon delivery, the valves are not only matched, but EBS has given them a 24-hr burn to confirm their quality. The component quality is overall high and up to EBS top standards.
BASIC SOUND AND FILTERS
As you have already concluded, there isn’t much room for tweaking on the T-90. Hit the power switch, wait a few minutes before you hit the standby switch on or off and turn up the volume for a good traditional bass sound. The basic sound has an organic, alive quality and reproduces the instrument in a natural, uncoloured manner.
The low end is airy and transparent without being fuzzy or unfocused and the bass control is surprisingly potent. The filter circuits of valve amps are often a bit more subdued than those in transistor amps but this here delivers a powerful low end and a compression that gives a meaty sound when pulling up the volume.
The top end has a natural sound, open in a way that few transistor amps can match. The treble control is very good for either taking some edge off the sound or diminish plucking noises, or to open up for flat picking sounds. The presence control is a bit more anonymous than the bass and treble filters, but it does offer a presence useful for bringing out aggressiveness in the sound when flat picking. The control also affects the performance of the power amp when pushed and it gives more bite to the sound.
For those of you thinking that the filter section is on the lean side, I must point out that the basic sound is so good that very few will feel the need for more filters. If you’re into a more high-tech sound, you may miss a midrange sweep control and the brightness in the upper highs.
WATTS, VOLUME, WARMTH
The pair of huge transformers makes the T90 weigh substantially more than a transistor amp, and since valves are expendables, the amp requires more maintenance. It is also more susceptible to damage if the speakers are not properly connected, and repair is more expensive.
On the other hand, valve amps use their output power more efficiently. This is because one can select between different output impedances, thus match the impedance with that of the speaker cabinet and achieve maximum effect. With an 8 ohm cabinet hooked up to a tranny amp’s 4 ohm output jack, one loses up to half the power. In addition, our ears perceive the distortion of a valve amp as more harmonic and natural, which means that you can drive it harder than a transistor amp, where the same amount of distortion is perceived as unpleasant.
One could find 90 watts being too little power in a bass amp, but I mean that it sands up more than well to a transistor amp of twice that power. At gigs on smaller stages, the T90 will sound clean and warm unless you pull up the volume too much. If you play raunchy rock´n´roll, just twist the volume knob a bit more and you will have a slightly distorted sound that will be thought of more as livelier than as overdriven. With the volume control halfway up, one hears an overdriven sound that still sounds good, and if you turn it up even more, it will not appear louder, just more overdriven. The overdriven sound is really great; fat, meaty, compressed and nicely held together. One can really hear the power amp sweat from the efforts of pumping out the sound. Not to say that the T90 cannot perform cleanly on a larger stage – it is just a matter of miking or DI´ing it, then feed the sound into the monitor system.
The valve driven XLR output sounds really good and manages to reproduce the lively, organic character of the amp, while at the same time keep the transparent high end. The flat-picked sound with a meaty low end and an upper midrange bite became my favourite. One must add that it can be hard to judge what adds the most to the sound; the input stage, the filter section, the output valve, since one cannot choose the pre/post input stage and filter. But this may be of little consequence, it all sound great.
CONCLUSION
What are the alternatives when buying a valve amp for club or pub gigs, which is where most of us can be found? When it comes to new valve amps, they are heavier, more expensive and offer more output power than necessary. With some luck, one can find 2nd hand amp tops with the same output and price as the EBS Classic T90, but hardly with the quality to match. The T90 is in a segment of its own, and will appeal to those who value quality, and especially those who have missed a genuine valve amp with not a trace of transistors or IC circuits.
For the valve amp die-hards, the limits within the filter section are neither a surprise nor a problem, and if you have never played through a valve amp, do go and see your local EBS retailer. The T90 sounds gorgeous, it has all the qualities one could ask of an all-valve amp and the filter section as well as the distortion fulfilled all my expectations. The idea of using a T90 for session work is good, too, especially with the valve-driven XLR output and the moderate output in mind. I predict that we will see more valve amps on the smaller stages next year.
EBS CLASSIC LINE 410
The Classic Line 410 is made of plywood and covered in black vinyl with a silvery speaker-front cloth. The corners are protected with metal and there are two recessed metal handles. The cabinet has four removable wheels, four rubber feet and holds four 10” speakers and a 2” treble horn with an attenuator.
The sound has a more rounded vintage character than the EBS Evolution Pro Line and aims more at those who look for a more traditional performance and sound. The attenuator of the treble horn also makes it possible to fine-tune the top end.
Classic T90 Facts
Type: valve-driven bass amp
Inputs: 2 x tele (Passive -20 dBv, 1 Mohm; Active -8 dBv, 100 kohm)
Outputs: 2 x Speakon (4 and 8 ohm), valve driven balanced XLR Direct Out with earth lift (-10 dBv)
Controls: Volume, Bass (+- 12 dB shelving @ 80 Hz), treble (+- 12 dB shelving @ 8 kHz), Presence (0 to +12 dB @ 5 kHz), Standby on/off, Power on/off
Preamp: Class A, Input/filter 1 x 7025, Bal Output buffer 2 x 12AU7, Power amp dirver 1 x 12AT7
Power amp: 2 x 6550
Effects loop: no
Output power: 90 W RMS
Land of origin: China (Hong Kong)
Size and weight: 537 x 267 x 243 mm (HxWxD), 17.1 kg
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Good quality
Good sound
Valve-driven XLR output
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None
