Here's your chance to jump on a great condition tube amp...the Ultravalve Tube Amplifier by Van Alstine. THESE ARE NO LONGER AVAILABLE due to supply issues.
In a side by side comparison with the Dynaco ST-70, this amp has a much more immersive soundstage and cleaner, tighter bass. Bottom line, it just sounds better.
***$1499***
**EDIT** Someone contacted me asking about three scratches on the top cover. There are no scratches on the cover. It is highly polished, so it shows everything.
It's a fantastic looking tube amplifier with a polished stainless steel chassis and a double-anodized, bead-blast-finish "champagne gold" faceplate. The amp was designed to be used with no cover/cage. Get this one while you can, because right now, they're not available.
Only reason I'm selling is that I have a Willsenton R8 with upgraded caps and KT77's and I sold my Schitt Freya+ that I had paired with this amp.
ACCOLADES:
• Absolute Sound's Product of the Year in 2010
• 2021 Editors' Choice Awards: Power Amplifiers $1,000 – $3,000 -thevinylcleaner.com
• Exceptional Value Awards for 2013 from tonepublications.com
DESCRIPTION:
The AVA Ultravalve is the ultimate ST-70 derivative. Descended from the Dynaco ST-70, the Ultravalve offers considerable improvements developed from over 30 years of engineering and design experience. What remains of the original Dynaco 70's design are some of the circuit basics (much improved), the biasing scheme (improved and regulated), and the basic 5AR4 vacuum tube R/C power supply (improved and supplemented).
The basic ST-70 internal layout has been maintained, however, all active electronics are now located internally, as you may have noted by the absence of an exposed circuit board like the ST-70. Coupling and feedback circuitry is now incorporated into a proprietary, double-sided ground plane custom designed circuit board. The power bandwidth has been widened to -3dB at 50 kHz and 5Hz while maintaining no feedback-related overload under any condition of use. The basic signal path and tube requirements remain unchanged from the ST-70. A single 6GH8A pentode-triode tube is used per channel. The 6GH8A pentode section provides the voltage gain while the triode section is the cathodyne phase-inverter. The power supply is tube-rectified via a single 5AR4. The push-pull output stage uses a pair of 6CA7/EL34s for each channel in ultralinear mode.
The Ultravalve uses a Dynaco PA060 power transformer and a pair of Dynaco A470 output transformers and is intended for speakers of 87 dB sensitivity or higher in 4, 8 or 16 Ohms. The power supplies are separate, isolated, high current, high speed, and analog, with very low output impedance, all of which contribute to providing the increased bandwidths, thus improving the audio circuit. The inputs also have adjusted ratios so that no input signal short of output clipping can drive the unit into gross distortion at any frequency. This makes the feedback loop work much better and clarifies the signal considerably. A solid reference to the screen grid resistor provides even more stability. The sonic results are noteworthy to say the least, this amp sounds incredible.
Premium "gold" input jacks are located on the back of the chassis. The red illuminated power switch is located on the front panel. The amp uses Pomona 5-way binding post output jacks for 4 ohm, 8 ohm, and 16 Ohm speakers. There is a chassis mounted fuse holder and a grounded heavy duty AC power cord. The top of the chassis has pin jacks for obtaining bias readings and has two manually operated bias adjusters. A voltmeter is needed to adjust bias, but I have set the bias before I boxed it up and the numbers were solid (and stable).
Dimensions: 13" wide, 10" deep, 7" high.
Weight is approximately 32 lbs. Shipping weight is a few more pounds. Shipping is $80 in CONUS via FedEx Ground and fully insured.
Ships insured, properly wrapped, well padded then packed, double boxed. A direct adult signature will be required at delivery. More images available on US Audiomart listing:
https://www.usaudiomart.com/details/649907605-ava-ultravalve-tube-amp-35wpc/
