OFF - FOR SALE: CSP2+ Decware Tube Headphone / Preamplifier (got Trades?)
Item #649368211Info: CSP2+ Decware Tube Headphone / Preamplifier (got Trades?)
||Cash, Money Wire, Interac/EMT
||3.63 (kg) Calculate Shipping
||27.94cm x 48.26cm x 25.40cm
||7 - Good (?)
Jul 20, 17 7:06pm (PST)
Edited: Oct 12, 17 9:59pm
Medicine Hat's Where E's At, AB
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I have available for sale (Or Trade for tube-based gear) the unit listed here.
Bought this two or so years ago from 2nd owner, who mentioned that the unit had been sent to the factory for a re-certification from the man himself. I have the invoice for this.
While my asking price is more than what I paid for it then, the reasons for that are several.
This unit has been improved by yours truly to make it possibly the quietest and most reliable CSP2+ available anywhere. The big differences with the factory version are:
- Power transformer has been replaced by a new Hammond 369HX. Smaller in size and offers a voltage that is "only" 100V DC higher than the final B+ requires. Factory X-former put out 180V DC more than B+ needed! New transformer fits the top plate using the same factory-drilled holes.
- Power supply went from a cheap C-R-C filter to a C-R-C-L-C-R-C, with a Hammond 5H choke added under the plate using factory-drilled holes for power transformer.
- The factory dropping/filtering resistor was a 5-watt 10K that ran incredibly hot (at over 4 watts dissipation) and which had been already replaced by Decware at least once. My version now uses one 470 Ohm @ 5-Watt two 2K Ohm @ 7-Watt resistors in the filter section.
- The filtering Capacitors in the p/s filter are now, in sequence: 4.7uf/10uf/22uf/33uf.
- Filaments are now properly referenced or "biased" to B+. No more arching tubes, loud random noises or ugly transients at start up.
- Filaments have also now been fed proper DC voltage within 6 to 6.7 volts, depending on the type of tubes selected. The "filament starving - special effects box" trick is no longer used on this one.
-A 0.75 Ohm @ 10-Watt resistor protects the filaments from over-voltage that these bigger X-formers produce.
- Chassis Ground has been separated from signal Ground using the 0.1uF X2 capacitor + Resistor.
- The Right tube/channel socket has been wired to use pins 6/7/8 as the top Triode and pins 1/2/3 as the bottom Triode. This helped me get a more symmetrical layout and a cleaner-looking build inside.
The latest power supply iteration as listed above (See last image) should allow you to run just about any rectifier tube that you see fit. The 274B tube seen in these images came with the unit, but it starts to "ring" after only a couple of minutes. It has always done so and as I don't normally use it, I will include it in the sale.
All the changes listed have taken me a bit of time to complete. I originally couldn't even use the unit as a preamplifier due to its factory-built short-comings. I never intended to use it with headphones because my ears ring slightly all the time and wearing headphones only makes the noise worse. In the day, my active sub would never shut off due to all the 60Hz hum this thing leaked out, even when turned off!
Partially lifting the signal Ground helped me get rid of the 60Hz hum, and the extra filtering has helped me get rid of the 120Hz hum as well.
Today I can easily pair this preamp with SS or tube amplifiers, set the Input trim two to five clicks down from Max, set the Output trim two, three or four clicks from Max, the gain on the amp at 50-70%, and control it all from the main Master on the CSP without any artifacts like it offered in spades before.
I also have an active subwoofer happily running off it with the built-in Mono output. The active sub plate amp does turn off as normal now.
My normal listening level only calls for a Master volume that varies from about 9 O'clock to 1 O'clock with roughly 50% gain on my amplifier.
Note: *If* I turn all the knobs to MAX I will get tube hiss, but ONLY IF I also turn my amplifier's gain to MAX. Consider that under no circumstances you'd *ever* need to push so much gain out of a gain stage such as this. The original literature lists the gain of the previous CSP version at almost 40dB!
I am letting this one go as I have now built a couple of tube preamplifiers based on Broskie's excellent "Aikido Cathode Follower" design and which fit my system's needs perfectly. I would like to free up some cash for future builds.
My price includes shipping anywhere in Canada.
1X 274B (unknown hours, rings), 1X 5Y3GT (low hours from NOS) & 1X 5U4GB (low hours from NOS) rectifier tubes. I will also throw in an extra rectifier or two from my stash of early American/Russian NOS tubes.
2X Gold Pin EH6922 output tubes (unknown hours, came with unit).
1X Haltron E88CC driver (unknown hours, came with unit).
1X Sovtek 6N1P-EB driver. Low hours from NOS.
1X Sylvania 6DJ8 driver. Japan. Unknown hours.
Free shipping within Canada.
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