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Our Notes: This unit is in excellent condition.
The SMS Classic Tube Preamp has become a popular favorite in our line of vacuum tube instrument preamplifiers. It is ultra simple and pure with just the essentials; gain, EQ, and reverb. The circuit is a highly upgraded version of the most famous of the all-tube "reverb" amplifier preamps from the '60s and '70s. The sound is flexible and familiar yet with an added degree of detail, dimension, and expression not found in the vintage originals.
As with all of our products, we continue to maintain our constant commitment to quality and attention to detail with the SMS Classic Tube Preamp. Combining a sturdy, lightweight, single rack-space aluminum chassis, with only the finest boutique quality signal path components, the SMS Classic Tube Preamp will provide an undeniable pristine, clean, warm and sweet tone. Whether you play pedal steel guitar, bass, electric guitar, or even electric piano, this preamp is the finest tool for the job.
For nearly all of his career, Jerry Garcia used the all-tube preamp section of a '60s Fender Twin Reverb amp as his main tool for gain and tone shaping. Of course, along with high precision quality component upgrades made to his personal amps to ensure extremely clean, reliable, and low noise operation, his rig also had a number of key components that helped achieve "his" tone.
From the guitars themselves, the choice of pickups, along with on-board guitar buffer amps, to the 12" JBL's, the heavy picks, the McIntosh power amplifiers, and most importantly, his personal touch, with only a couple of minor exceptions, one virtually constant factor in his rig was the Twin Reverb preamplifier.
The JG version of the SMS Classic preamp is only slightly modified from our standard guitar & pedal steel version. In addition to the ultra pure circuit, it includes a few component changes that to the best of our knowledge and our ears help to make this preamp deliver that elusive sound as closely as possible.
This is an instrument level input with a typical 1MegΩ input impedance. It should comfortably handle most any guitar, steel guitar, bass guitar, or acoustic instrument levels.
This knob controls the loudness, obviously. One thing to remember is that this preamp is very much designed as a clean machine, and it is not meant to be cranked up and overdriven like other preamps. So keep that in mind as you put the "Classic" to use.
The up or "bright" position is just like what you'd find on many classic tube amplifiers. The middle position of the switch is off or neutral. The down or "dark" position on your particular SMS Classic Tube Preamp JG provides various functions depending on your particular model.
Controls the amount of treble
The midrange control on this preamp is a cut-only function. Cranking the "MID" knob will approach a flat response but never boost mids. The voicing of this preamp will always tend to have some degree of midrange dip, just like any classic guitar amp. Mid settings below 12-noon will have subtler changes in the sound compared to settings past noon.
This knob controls the amount of bass frequencies in the sound.
This knob controls the amount of reverb that gets blended in. The internal reverb is a high quality 24bit "hall" type that has a realistic and natural sound that blends well with just about anything.
Up is on, down is off. The little blue light will tell you it's on. Remember that these are tubes, and they typically take about 12 to 15 seconds to warm up and start working. Also, tubes will sound much better after 5 minutes of being warm, and reach their optimum tone after about 20 minutes. It's recommended that you generally leave the preamp on once it's on. Too much powering on and off can age the tubes prematurely. Also since it's just a preamp, the unit consumes very little power and creates very little heat (unlike a tube "power" amp), so don't be afraid to leave it on for many hours at a time if you know you'll be using it frequently throughout the day or night. Don't leave it on 24/7, but you get the idea. If you're on set break at a gig and want to mute your rig, just turn the gain down to zero instead of turning it off
On the back of the preamp there is an output jack. This jack is an unbalanced type output which means you should use a simple guitar-type cord to make the connection. It's best to keep the length of your cable run as short as possible. The output level from the preamp can be very high if you drive the preamp hard enough, so keep that in mind when you connect the preamp to a power amplifier, a DI box, an effects unit, or a recording interface.
The knob next to the rear output jack is the "pad" control. This preamp naturally has a very hot output level, too strong for many inputs on power amps and other line level devices that may follow the SMS Classic. For starters, leave this knob set a bit below “noon”. See how this works with your particular setup and adjust from there. Quite often, the front panel "gain" knob will sound best in the "noon" to "2 o'clock" range. With that in mind, you can then dial in your ideal "pad knob" setting. This will allow the most flexibility with the controls on the front panel.
|TUBES (2 total)||: 12AX7|
|DIMENSIONS||Width: 19” Standard rack mount width
Height: 1-3/4” Standard single space rack unit height (1 RU)
|FUSE||Internal 1/2-AMP Slo-Blo|
|MAINS||Internally set for either 115VAC (North America)|
|OUTPUT IMPEDANCE||25kΩ (approx.)|
|CHASSIS||Anodized aluminum face, powder coated aluminum chassis|
|POWER||Standard IEC AC power cable (SVT style recommended)|
|REVERB||24bit “spring” algorithm|