Smash DHT Preamplifier Kit Specs


Introducing: Smash DHT Preamplifier Kit

The Smash DHT includes:

  • Three pairs of inputs
  • Two pairs of outputs
  • Separate volume and balance controls
  • Shunt regulation of the high voltage supply
  • Regulated filaments
  • now includes Smashup Upgrade kit

The Smash uses directly heated 4P1L tubes wired for triode operation as voltage amplifiers. Cathode bias is achieved by our tried and true HLMP6000 LED method. Shunt regulation of the solid state high voltage supply (using ultrafast recovery rectifiers) is via a 0D3 gas regulator and filament supply regulation is via an L200C regulator. The audio circuit is completed with the simple addition of high quality plate resistors and output capacitors.

Three pairs of inputs allow for multiple sources and two pairs of outputs allow for the connection of two amps per channel for multi-amping speakers, or a single power amp for speakers and a separate subwoofer amp or dedicated headphone amp. RCA jacks are gold plated.

We have had many requests over the years to incorporate a balance control into our preamps. We introduced a balance control in the BeePre 300B preamp and we have carried that implementation over in this preamp.

The chassis arrangement is similar to our other kits. We provide the usual high quality level of American made transformers, an American manufactured 10” x 10” chassis panel with our cool new random brushed artisanal finish and lovely Pacific Northwest milled alder wood base that glues together easily and looks great with a wide range of builder-applied finishes. Sockets are ceramic.


Gain @1kHz: 10dB
Maximum output: 7Vrms
S/N: -88dB
Channel Separation: 120dB @500Hz
Input impedance: 56Kohms with volume and balance controls centered
Output impedance: 1.6 Kohms

So how does it sound? Just as its price indicates the sonic character of the Smash falls between the Quickie and the BeePre in terms of resolution. It has the same “DHTness” – that sense of delicacy and realism – as our other two preamps. It will make a great match to the Reduction phono preamp, and it works great with our Seductor SE EL84 power amp.

Why Smash? One day Grammy winning mastering engineer Paul Stubblebine came to Bottleheadquarters for some listening, and he asked to hear the new preamp prototype. Josh brought the preamp up from the lab and on the way to the listening room it slipped out of his hands and Smash! It looked pretty sad with a big bend in the chassis but it fired right up and sounded great.


SMASHUP – In the stock configuration of the Smash, priority was given to having complete regulation of both the filament supply and the high voltage supply. Accordingly, a balance was struck between grid bias, plate current, and load resistance to achieve good distortion performance with adequate gain and a useful amount of output. With the Smash-up upgrade, high voltage regulation is taken over by our hybrid shunt regulator technology, fed by a C4S constant current sources and a 6SN7 dual triode. This is the same shunt regulator technology found in our premium products: BeePre, Paramount, and Mainline. Unlike the single 0D3 in the stock Smash, the Smash-up dedicates one shunt regulator to each channel for enhanced noise performance and channel separation. In addition, by adding a C4S load to the 4P1L’s themselves, we are able to increase the gain, lower the distortion, and bump up the bias on the tube to allow it to accept more source voltage and provide more drive voltage from the preamp. We feel that this kit is such a great upgrade to the stock Smash kit that we now include it in the standard Smash preamp kit. You should build the kit in stock form first, and add the upgrade whenever the mood strikes!