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The DPA-300B Mono Block Power Amplifier

The dpa 300B is an unique Highend Hifi poweramplifier. It is not Single Ended or
Push Pull, but uses a differential (balanced done correctly) amplifier circuit topology
to provide the best sonic attributes of both, without their weaknesses.

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Using the 300B tube in monoblock configuration, it has twice in a row won the
Product of the Year Award from

Product of the Year 2003, Audiolics Anonymous Chapter 52

Blue Note Best Of 2004 Award, Audiolics Anonymous Chapter 63


Allen Wright's excellent DPA 300B amplifiers with the MaxxHorn Immersions share the spotlight in a mini review by Roger S. Gordon, Positive Feedback, Issue 21., scroll down to Rhino Acoustics/Vacuum State. This is a partial extract:

"The combination of the Vacuum State dpa300Bs with the MaxxHorns was a marriage made in heaven. All the problems that I had heard on my initial listen disappeared. With the dpa300Bs, the sound was coherent, detailed, dynamic. This was easily the best sound that I had heard at the show. After half an hour of listening I had to leave in order to meet some friends for dinner. I had just left the room and was saying good bye to Allen out in the hall where he had been conversing with one of the Rhino people when I suddenly heard Bela Fleck's Flight of the Cosmic Hippo coming from the room. I know and love this bass guitar piece and use it as my test track when demoing subwoofers. Back into the room I went. What I heard was the best sounding Cosmic Hippo I have ever heard and I have heard it on quite a few systems including my own."

Thank you Allen Wright, Vacuum State Electronics for your very special efforts to bring your amplifiers to our room for a very special audition.


Bob Spence

Bob is the prime mover behind the Rhino Acoustics Horns, their URL is:


Amplifier Product of the Year for 2003

The revolutionary dpa300B monoblock Power Amps are now in production!

Available as both kits and fully finished products, the dpa300B brings a radically new topology and sound quality to the world of Tube Power Amps.

This amplifier was first shown publicly at the 2003 VSAC Convention ( won an Amplifier Product of the Year 2003 award in December 2003, and (as we understand) is in the running for the same award in 2004. Read also Lynn Olson's VSAC Report ( including the dpa300B.

In previous announcements, several versions of this amplifier using KT88 output tubes were described, but over the intervening year these designs, while spectacular, were proven to be sonically inferior to the extreme qualities of the 300B based model, and as they would cost almost exactly the same to produce, have been quietly dropped from our production plans. This allowed us to optimise the circuit for 300B tubes, and further increase itís sonic virtues.

The dpa300B can use all 300B tubes from the classic Western Electric 300B (and itís lower priced clones) right up to the monster Ď52 variants from the Prague consortium of Kron, Emission Labs and EAT. Classic 300Bís produce 18 watts of output power, the biggest tubes easily make 25 watts. Unless otherwise client specified, dpa300Bís are built to use the classic 300B tube, but to gain the extra power available from the bigger tubes all one needs to do is change the value of one resistor per monoblock. This is easily done by your deale