Friday, 10 April 2015

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Dyna Hafler Rebuilds

Hafler
Amp

Dyna
Amp

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Preamp

Ordering Information
For help
with your order, Look here. Price lists, order forms, shipping
information and everything you need to know to get the stereo equipment
you want.

Home
Dyna
Amp

Ultimate 70 Vacuum Tube Amplifier
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Price: Factory wired (your chassis): $999

Complete kit: $449

Plans and bare PCB: $149
Circuits:
Ultimate 70
Chassis: Your Dyna St-70
or AVA-furnished Dyna St-70 (subject to availability)
Kit
options
Jack set: $75
Output tubes (set of four): $109/set

Rectifer tube: $25
(The above options are included in the factory wired
rebuilds)

The AVA enhanced pure vacuum tube amplifier for your original
Dyna St-70 chassis.

Over the years, we have gotten many calls and letters asking for
service and upgrade help with the long-out-of-production Dynaco
St-70 vacuum tube power amplifier. A thorough discussion of the
basic operational parameters of vacuum tube power amplifiers in
general and the Dynaco St-70 amplifier in particular was
presented in our July, 1982, issue of Audio
Basics. That issue also included directions to correct
some of the amps worst problems within the context of its
original circuit board. You can
view it online for free from the AVA website.

The Ultimate 70 is a new AVA circuit set for the Dyna
St-70 chassis that 2005 AVA circuit for the Dyna St-70
chassis that goes far beyond what we describe above. It consists
of a brand new motherboard incorporating significant circuit
enhancements, all new modern parts, and an improved layout. The
audio circuit has been carefully engineered for the widest
controlled bandwidth and stability under all conditions. Taking
advantage of what we have learned from our Transcendence Seven
and Fet Valve R-series products, the Ultimate 70 incorporates
five regulated power supplies, including an isolated
regulated bias supply. The result is the purest musical
reproduction possible.

The Ultimate 70 replaces our highly regarded classic Super
70i rebuild that has had a production run of over twenty
years. It was time now, with experience learned from engineering
our acclaimed hybrid preamps and power amps, to see how much
further we could push the envelope of pure vacuum tube amplifier
design, and we have pushed it beyond our wildest expectations. Do you already own a
Super70i?

We think you will love the Ultimate 70 more than any other tube
amp you have ever heard, price not an object. It is just simply
lovely sounding. It takes every last bit of grain away from your
records and CDs, but takes nothing else away at all. The highs just
float. Transparency, detail, definition, range, and dynamics are
wonderful. It's got a midrange to die for and bass extension and
control you would not believe possible at this power and price.
The sound stage is huge, the depth is pure reality, and the emotion
of the music is all there, like you have never heard before.

With a good set of tubes, the Ultimate 70 will output about 33
watts per channel RMS up significantly from a stock St-70.
(Dyna's original 35 watts per channel rating was rarely achieve
under real-world conditions.) It sounds like much more power than
that, driving our 87 dB efficient Biro L/1 speakers easily.

The Ultimate 70 can be delivered to you in three different ways:

As a do-it-yourself rebuild kit (AVA Input-Output Jack Set,
new output tubes, and new rectifier tube available as extra-cost
options).

As a factory-installed rebuild to a Dyna St-70 chassis that
you provide (all new tubes and the AVA Input-Output Jack Set standard).

As a factory-installed rebuild to a Dyna St-70 chassis that
we provide (depending on availability; all new tubes and the AVA
Input-Output Jack Set standard).

You need a wired and working Dyna St-70 to start with, complete
with functioning transformers, rectifier tube, and output tubes.
(Replacement tubes are available from AVA, replacement transformers
are not.) The rebuild replaces the entire audio circuit (including
the small signal tubes), the quad filter capacitor, and the bias
supply capacitors and resistors, and so most old problems will be
thrown away along with the old circuits. Instructions for bias adjustments
and basic troubleshooting are included in the manual. The PC card
is solder masked and silk-screened on both sides to make it easy
to build. Rebuild plans and a bare PC card are available alone for
those who want to furnish their own parts.

An optional AVA Input-Output Jack Set provides heavy-duty 5-way
binding posts for your speaker connections. The new gold-plated
input jacks are spaced further apart than the originals, allowing
modern cable ends to fit better.

The Ultimate 70 amplifier (like all tube amplifiers) runs hotter
than a solid-state amp and will need ongoing maintenance, periodic
bias adjustments and re-tubing. This is because power tubes, unlike
the small signal tubes in our preamp and Fet Valve products work
hard, operate at high voltage and high current, and thus don't
last as long. Our small signal tubes run cool and tend to last for
years and years.

Why the bother? Because a good working Ultimate 70 with a good
tube set, properly adjusted, is a great little amplifier! Because
it is faithful to the spirit of the music, absolutely pleasant,
and rewarding to listen to on any rationally efficient loudspeaker.
Because you will find this carefully engineered AVA project is simply
fun to do.

The AVA-enhanced pure vacuum tube amplifier rebuild for your original
Dyna St-70 chassis available as a kit or factory-wired.

©
2011 Audio by Van Alstine