Dynaco st70 Custom EL34/6CA7 Vacuum Tube Power Amp W./Tubes
- Condition: Used
- Price: 1938.79 EUR
- Status: unsold
- Item number: 205024897948
- Bids: 0
- Seller: fineg-us2015 (229|100.0%)
- Seller information: non commercial
- Item location: Philadelphia, Pennsylvania
- Ships to: US
- Shipping: EUR
- on EBAY
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Description
This high-power tube amplifier is a custom-built unit from Tubes4 Hifi, featuring a Dynaco ST70 Variant model. With an audio output of 44 W, it has two-channel RCA audio inputs and RCA and banana speaker jacks for maximum flexibility. The amplifier class is AB, push pull parallel circuit with 2 input channels and 4 outputs The unit is designed with an analog signal path and a brown color aesthetic. It was manufactured in the United States in 2023 and includes many tubes, including EL34, 6CA7, and can run the Big Boy power tubes 6550 & Kt88; the original Dynaco ST70 was an excellent , well designed, high quality Transformers and producedhigh fidelity performance from a relatively easy to understand,simple circuit. But it had a number of flaws that are easy to fix, improve or eliminate . If you follow my modifications, you can transform any Dynaco into a superb, compact super amp, capable of embarrassing much more costly amps, even the big names My story : About 20 years ago , I decided to see if tubes actually did sound as well as tube heads claimed. So I did research on tube, amps, preamps, integrated amps, monoblocks; studied the respected names ( Marantz. Macintosh etc. ) but I seeing Dynaco mentioned as a good quality amp, sold as a kit that c tubeheads all seemed to agree that vintage Dynaco equipment was perfect for a new would be tube aficionado. It readily was relatively eazy to find, of quality obtained was very favorable relative to the cost of acquiring, the designs were well thought out , and easy for a novice to understand, and restore. I soon found many vendors of parts, eefeupgrade kits, vintage hard to find tubes , even copies of old schematics! My first tube amp was a prebuilt Velleman k4040 amp., i knew almost nothing about tubes, but this monster had 8 El34 SED Russian power tubes as a complete set of preamp , phase inverter and. Rectifiers included. But the only number that interested me was the power 80 watts per channel. I had recently purchased a pair of Cerwin-Vega 3 way E 710 98 Db efficiency and s massive power capacity of 200 watts per channel. I bought the amp and set it up, but no sound? The directions rsferred to a preamp I loved that velleman ; but i was forced to b sell it becsuse my cat found it fascinsting and was alwsys nosing around. It no doubt attracted to fhs warmth and orange glow from 8 sl34 and eventually get. Burned or shocked So I hooked up a dynaco sd site. Bought a kit to build and enjoyed it for years, but i felt it could be much better with a few key mods. I C ad been studying amps tube , trabsformerz for years. Even as amateur, I spotted serious flaws and camee uoo with a plan to make a good amp superb, I asked the guys at tubes4hifi.co if they could build from the ground up if listed my mods? They agreeed So i pointed all the flaws annd my proposed fix 1) it had a terrible ochassis looked cheap Even when new 2) unput jacks on front cover. Inconvenient 3 rhe whole top plate had too much stuff. It looked likea train wreck 4) quad cap can unreliable, can’t be high quality if you cram 4 elements in tiny can . It’s also an ugly eyesore 5))Too many exposed circuits 6 circuit board exposed on top easy to damage 7)ugly tube sockets built into chassis face solely to measure bias? 8)Power supply not sufficient, amp needs 200 milliamps to operate. This requires the lone rectifier to be running its maximum capacity 100% of the time, not good 10) Triode to pentode not needed. This amp is designed to use pentodes. Tube designers had reason to have 3 grids in pentode. Let the tube operate as it should. My.solutions: While browsing on ebay , discovered a guy selling hand made oak and Chassis for amps. They were tight in space ,but built. Bottom plate had plenty holes to cool hit parts.itseemed too small, the custom made a top plate and i allowed only transformers and tubed on top All electronicd mountrd under fop plate. Installed 2ndfectifief in place of quad cap can. Paralleled rectifiers using 2 Emission labs C mrdh plate. These are hanmade in Czech Republic. Fgey claim tobe electrically identical to olxWestern Electric 274 b . Sfter. After Buying they remain testing good.fhdy have lasted over 20 years.
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