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Welcome to Decware


Classic Stereo Preamplifier

OTL headphone amp


Model CSP3


The  CSP3 is a purist audiophile line stage / OTL headphone amp.   Its focus is on sound quality for both preamp and headphone use.  It features two pair of RCA inputs, two pair of RCA outputs and two headphones jacks in the style of your choosing.

There are no circuit boards, everything is point-to-point wired and laid out so that the part leads create the circuit with almost no wire and minimal solder nodes in the signal path.


The circuit uses three single-ended-triodes and tube rectification.  The audio circuit has zero negative feedback and may be configured with audiophile film caps (as shown) or copper foil caps for a small upcharge.


As a preamp the CSP3 is compatible with everything be it tube or solid state -- it won't matter because the preamp is fully adjustable.   You simply hook your amplifier to it, set the volume around 1/2 way up, and adjust these two output level controls           until your system reaches a normal listening level.  That's it.

The switch in the very front is your source select.  It features silver contacts and silver wire.


Behind that is your volume control.  You may choose from several knobs.  Behind the volume knob are the input level controls, one for each channel.  These are used primarily for headphones that get too loud too quick.

The input level controls let you dial in a wide range on the volume control for any set of dynamic headphones regardless of their efficiency.

The headphone jacks can be your choice of 1/4 inch, 4 pin XLR or dual 3 pin XLR.  Only dynamic headphones are compatible.  We recommend 80 to 600 ohms.  Planar headphones will not work on this model.  We have a dedicated headphone amp for planar headphones (model Taboo).

This preamp adds body, density, weight and tone with absolute transparency.  It is a joy to listen to both in front of an amplifier and through headphones!  Works equally well with tube and solid state amplifiers.

What sets thE CSP3 apart?

  • The Sound - it is one of the better sounding tube preamps made.

  • Massive tube rectified power supply 6 times larger than needed.

  • A signal-path featuring 2 resistors and 2 capacitors.

  • Direct-coupled single-ended triodes running in class A.

  • Blended AC and DC heater supply for tubes.

  • 4 revisions spanning 20+ years. 

  • Customer Feedback from many 1000's of sales create a highly evolved product.

  • Exotic internals.

  • Output level controls for each channel

  • Input level controls for each channel

  • Master volume

  • Optional second mono or stereo output for subs.

  • Based on the popular 6922 signal tubes.

  • 1/4 inch and 4 pin XLR headphone outputs available.

  • Point-to-point wiring with no circuit-boards and zero negative feedback.

  • Designed by audio guru Steve Deckert.

  • Parts and Labor from the USA.

  • A Lifetime Warranty.


You may choose from several kinds of wood bases.


The Walnut base is standard, but for a small upcharge you can have Cherry, Maple or Oak.  Additionally we can make them in custom woods and finishes with a more substantial upcharge.  You can choose the wood from within the shopping cart.



Knob choices: ebony, gold, black chicken head, cream chicken head, rosewood



Anniversary Mods

Anniversary mods for this preamp come in three variations:

Level 1 - Poly bypass caps in the power supply increase detail and blacken the    background even further than it already is.

Level 2 - Copper foil bypass caps update the poly caps used in level 1.

Level 3 - Copper foil bypass caps and internal tube regulation are added to bring the unit to the same sonic performance as our anniversary model, the CSP325.

These mods can be done at any time during the life of the product.

You can select which mods, if any, you want during the check out process.

Do you need anniversary mods?  No.  We have sold this unit bone stock for 20 years without any mods because mods speed things up bringing higher resolution.  The world is only now just getting to a place with digital where the jitter is low enough in a similarly priced DAC or Streamer to justify the improvement.  In years past, the mods would just let you hear more of what was wrong with your source.

This means that by nature the unit is laid back with great liquidity, never edgy and that is never a bad thing.  But if you have a great source and just wanting to push what is possible then mods might be great for you.  Between level 1 and level 2 modes the level 1 is by far the better value since it brings 85% of the performance of level 2.


Weight: 17 lbs. ea.

Dimensions: 8.0" H x 8" W x 16.0" D



Inputs: 2 pair RCA with silver selector switch

Outputs: 2 pair of stereo RCA jacks or 1 pair of stereo RCA and 1 mono RCA.

Gain: 20dB into 100K Ohms.

With a 2 volt source at 0dB there is adjustable output from 0 to 30 volts into 100K Ohms



Gain: 11dB into 300 ohms.

Warranty: Lifetime to original owner

Weight: 16 lbs. ea.

Dimensions: 8.5" H x 7.250" W x 14.75" D

Circuit type: Single-ended Class A Triode OTL

Output Adjustable: 0 ~ 30 volts into 100kOhms

Input voltage: Adjustable

Noise / Hum: Less than 0.5 millivolts

Input Impedance: 100k ohms

Output Impedance:  600 ohms with supplied tubes.

Output Impedance can be dropped with alternate 6N6P tubes.

Feedback: ZERO negative feedback used

Rectification: 5U4 tube rectification

Signal tubes: 6N1P-EB, 6N5P, 6N6P or 6922 

Biasing: Self-Biasing circuit - never needs adjustment

Signal Caps:  Audiophile grade film or copper foil

Filter Caps: 500V German F&T

AC: Fused IEC connector provided with removable power cord

Consumption: 65 watts at full power

Input jacks: High Quality RCA type 24K Gold / Teflon

Output jacks: High Quality RCA type 24K Gold / Teflon

Headphone jack: High Quality dual 1/4 inch stereo jack or dual 3-pin XLR or dual 4-pin XLR or one 1/4 inch and one 4-pin  XLR

Warranty:  Lifetime to original owner / 90 days on tubes



CSP / 2002 ~ 2006

The original CSP featured a simple steel chassis, and the output level controls were internal. It was a line level preamp only. 


CSP2 / 2006 ~ 2010. 

The second version featured an upgraded chassis and a completely new circuit featuring an OTL headphone output.  Line level adjustments became external output level increased from 5 volts to a max of 30 volts.


CSP2+ / 2010 ~ 2013. 

Added set of variable input trim controls used to fine-tune the output level from your source. This allows you to adjust for any headphone efficiency.  Internally, there were also come layout improvements.


CSP3 / 2013 ~ present. 

Features a new layout, high-mass steel plate, and an improved layout makes it possible to offer the larger-sized copper foil caps.  Sonically this unit has improved transparency and blacker backgrounds. 


Since we don't have dealer's and we sell our amplifiers directly to the customer, our customers have a direct line to us.  As a result, Decware support is legendary for over 20 years.

Support is not only a phone call or email away at any time, but when you purchase this amplifier you join a huge family of customers who also own one and enjoy supporting each other on the:



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Manual is in a .pdf format



Made by hand in the USA and sold wholesale to the public with a 
L i f e t i m e   W a r r a n t y  !

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These are hand-built to order.  There are presently lots of orders on our real time build sheet.   A 10% deposit secures your place on the list with today's date and time stamp.  Balance is due when it's ready to ship. You will be sent a final invoice with the total price including actual shipping costs by our office during your wait.   


The CSP3

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