SBS Designs SP-1 Valve Expander    


Introduction to SP-1:

The SBS Designs SP-1 (SP-1 = Special Processor #1) is one of the most unique vacuum tube warming devices ever produced, offering flexibility and features that have not been offered before to the Pro Audio & Audiophile market.

The SP-1 is a hand made High Fidelity processor 5 yrs in the making that will let you record and add desired flavor to music in ways never achieved.

Sp-1 was carefully thought out in the original conception and put through years of a prototype testing in different applications. While the opinions and suggestions of numerous individuals who work with audio for a living were considered – all in order to improve this product to make it the most useful vacuum tube warming device available on the market.

The SBS Designs SP-1 will bring a new level of excitement your source material in a club application dealing with substandard MP-3 down loaded and compressed files featured by end users.

Applications for SP-1:

The SBS Designs SP-1 was designed for Professional Recording Studios, Home HIFI Audiophiles, Nightclubs / Dance clubs & the live sound PA Market.

What is SP-1?

SP-1 Valve expander that is user adjustable designed to Sweeten up & expand the source to your personal taste and to improve the dynamic range on any given sound system or source on the fly.

A carefully designed expansion process will bring out exciting detail that is so often masked by recordings that are compressed and engineered to be mono compatible. The SP-1 will also bring back amazing detail to digitally stored / processed recordings which where subject to data reduction processing.

How does SP-1 work?

SP-1 has a sub bass expander and an extended range of top treble expander. These expanders are top quality fully analog which use no vca’s and contain no noise or distortion generators. They add dynamic range by controlling the target frequencies with photo resistors.

Two front panel threshold controls, allow the end user to adjust at what level the low frequency and high frequency expanders begin to increase dynamic range, turning down a control all the way bypasses that expander.

These expanders are subtle and employ control feedback systems to monitor the depth of expansion and prevent obtrusive runaway operation, even if the controls are turned up too high. The low frequency expander has a program dependent release time limit, so it will not add any annoying droning or rolling bass to a source.

The high frequency expander operates relative to the overall spectrum of the music being played, so it will not produce over pronounced highs that sound like someone turned up a treble control too far. These expanders will not create something that is not in the recording. The material must contain low and high frequency information for the processor to work with.

The expansion circuit in turn feeds a two stage zero feedback tube amplifier these tube amplifiers are the same class A types used as gain stages in vintage recording equipment. They are not designed to create tube distortion like a guitar amp, but they will warm the sound by imparting the natural characteristics of the triodes. Part of the reason is that we do not choose exact matched tubes between left and right channels, and the slight natural differences in transfer function between tubes improves the stereo image of an otherwise clinical recording. The warmth of the tube is enhanced by improving the dynamic range of the music ahead of them.

I/O rear panel:

The SP-1 rear panel has a variety of inputs and output choices for the end user.

The SP-1 can be hooked up with the RCA unbalanced inputs and outputs to be used in an unbalanced effects loop or an unbalanced main output of a mixing console. SP-1 can also be used in a home high fidelity sound system for clients that like single ended circuits.

The SP-1 offers XLR Balanced inputs and outputs for mixing consoles, in recording studios and in audiophile sound systems for clients that run fully balanced sound systems.

The SP-1 offers a HIFI Phono preamp stage designed for phonographs, this feature was offered to the end user in studios for sampling & for audiophiles that want to add a really unique flavoring with tube warming to the source.

The SP-1 offers a Line or Phono level selection switch on the rear panel to adjust for line or Phonograph use.

Bonus SP-1 Features:

The SP-1 offers some amazing unique features to give the audio enthusiast many options to playback and record music offering a signature sound & texture like no other component has offered before.

SP-1 Reverse Phono curve:

The SP-1 provides a reverse RIAA curve output so you may use your favorite phono pre amp with a Line level source, for example CD players, Lap tops, Drum Machines, Keyboards or Live instruments that can run line level for more flavor to the source.

You can also use a phono input on a mixer using the reverse Phono curve and keep a line input free for other sources. The SP-1 is the 1st processor of its kind with these features and layout to offer this option.

Line level & Phono level Inputs & Outputs used at the same time.

With the SP-1 you may use the phono & line level inputs and phono & line level outputs all at the same time. The SP-1 was designed to be used with any input on a mixing board.




Recording Studios
Mastering Studios
Live PA
Night Clubs
Touring DJs


Max line level in = + 21 DBu depending on rear pot setting
Max line level out = + 19 DBu
THD thru solid state circuits = .03%
Second harmonic distortion thru tube output section = .3%

Power Requirements

25 watts

Frequency Response

12 Hz to 30 kHz +/- .1 Db
Roll off: low = – 2 Db @ 8 Hz, high = – 2 DB @ 44 kHz



10 years