The PRE IV is a signal output transformer (OPT) de-coupled 71A/45/300B tube output stage based, zero negative feedback (zero NFB global or local), line pre-amplifier design. The DHT tube output stage is similar to the output stage as found in our DAC V. It is a further development of the PRE III power line stage pre-amplifier. The difference in line stage design to power amps is that our goal is the preservation of the signal integrity while minimizing the output impedance and not really signal amplification and reduction of output impedance. Therefore PRE IV only uses 2 x 6J5 single triodes instead of 2 x 6SL9/6SN7 double triode tubes to drive the DHT stage. Consequently, PRE IV offers the sound of DHT tubes plus has very powerful output to drive any power amp, with output impedance below 10 Ohms while having only a very modest gain of 3.
The sound is mature, large & holographic (as one would expect from DHT) with scale, authority and a lot dynamic bite but above everything very transparent comparable to a great passive volume control. It is a great enhancement to any tube power amplifier, driving a sources (DAC or Phono), which has a weaker small signal, indirectly heated tube based output stage.
Available in either double C-core Super HiB transformer version or Pemalloy core version (Special version) and the limited production Signature version on request.
SW1X Audio Design™ PRE IV Line Pre-Amplifier Features:
Tube Compliment: 2 x 6J5, 2 x 45 or 2 x (71A/45/AD1/300B) , 1 x 5Z3/5U4
Note: Due to SW1X Audio Design’s ongoing research and development process, specifications are subject to change without notice.
Dimensions: Height (mm) 250 x Width (mm) 440 x Depth (mm) 400
Weight (kg): 23
Max Power Consumption (W): 80
Output Noise, Unweighted (mVrms): < 0.5
Output Impedance (Ohms): <10
We do not recommend purchasing a key system component without first auditioning it carefully, which is why we have demonstration rooms and a flexible home loan policy.
However in certain situations it can be difficult for people to get to our showroom and for those instances we can offer our mail order service.