The Abraxas Audio Build Story
Darling #8 Designed from scratch to be quiet enough for headphone usage, or the most sensitive of speakers. This amp runs both the 1626 "Darling" tube and the 12V6GT. This is a substantial build, wider and heavier than the seven (7) previous Darlings. That is mostly due the larger output trannys and the heavy duty DC power supply for the heaters. The DC power supply for heaters is not often seen in tube amps, and this design feature makes for very quiet amplification, which headphone listening demands. The builder did a lot of listening to get the heater supply just right. As you know, DC heating is different from AC heating and tubes respond to DC heating differently according to their type. In this case, a final value about 5% below rated seemed sonically the best. While this was being built, I suggested to Jeff that for some amps I owned, lowering heater voltage by 5% improved the sound (subjectively); moreover, it would lead to very long lived tubes. In addition to the 1626 triode-power tube, the amp supports the 12V6 in triode connected mode. A switch changes the cathode bias to accommodate each tubes operating point. In both cases, the tubes operate with the same effective plate voltage and current. From the Builder: “In fact, it is quite amazing how good it can sound, and I am going to put up a page on how to convert a Darling to 12V6 operation as the 1626 is getting scarce.”
The front end tube is the 5965, which is an excellent electronic and sonic match for the 1626 and works quite well with the 12V6. Options are the 12AV7, 12AY7, 12AT7, 7062 and any other of these medium-mu signal tube-families where the 12.6V heater current does not exceed .225A. The 12AV7 worked nicely with the more sensitive 12V6. This amp responds very well to tube rolling of the single front tube, followed by the 5Y3GT. Different 1626 and 12V6 also sculpt the sound. I will include three different brands of 1626, 12AT7/5965-type and 5Y3G. You will have fun and learn the impact of tube rolling in this lovely amplifier. The amp uses a 5Y3 rectifier, and any 5Y3 type may be used, but not other types. The power supply is set up to provide the correct operating voltages and currents, and changing the rectifier to another type may result in exceeding the 1626's power rating.
The amp delivers about 700mW/channel from the 12V6 or 1626. Output speaker impedance is 8 ohms. Small power amps like this won't appreciate a lower load, but 16 ohm loads are fine. As you can see carefully selected high quality parts were used throughout. The output stage cathode biasing is bypassed with a low-loss Nichicon and further bypassed with a high value MKP (polypropylene). PIO caps were chosen for coupling after sampling many others. The final high voltage B+ is also film bypassed. The power supply is the CLC type for lowest noise. Quality metal film resistors used throughout. Even the DC for the heaters is filtered CLC for maximum quietness. The builder feels this is his greatest and final Darling. ‘Eight is enough’. The prior seven were sold to delighted buyers—none have ever come back on sale, insofar as I know. This one is the only one designed from the ground up for headphone use—and I am the original buyer. I have owned it for three years with zero issues. It is wonderful with my Senn 600/650. Dead quiet. I sold my Grado ‘woodied’ SR-225, which I have always regretted. My feeling is this amp would be very synergistic with Grado headphones, which tend to be a bit bright and narrow in sound-stage. The amp is not powerful enough to drive my AKG-702. Sensitive headphones would be best, impedance should not matter. This amp has excellent lateral and depth of stage, and the midrange is as good as it gets. It has great bass and clear and refined highs. There is no upper-mid or treble ‘etch’. Totally non-fatiguing sound.
The pictures are the original pictures on Abraxas Audio webpage. The amp looks great, I can find no significant flaws. Rating it 8/10, due to age and to be somewhat conservative. If you search “Darling D8 Mar 2010 - abraxasaudio Tube Amplifiers” you might come across the build page, but all the info is above. I will include a few 5Y3 rectifiers and 12AT7/5965 type tubes and several pair of 12V6 and 1626 matched tubes, all will be NOS-ANOS and test perfectly on two testers. Note the lead position is ultra-sensitive (as for all of Jeff's amps), but I will check the tubes out before sending and they will all test NOS/A-NOS and be quiet. The hot glass will be excellent types. The serious buyer will get list of tubes via email before we close. BTW, the transformers you see underneath are DC heater supply transformers, I believe. I do know that the old stock Japan-made OPTs are on top underneath the red-casing, separate from the choke and PT on top the case that you can see individually. All in all, a very classy build. The amp is in excellent condition aesthetically and functionally. It is a beautiful and unusual piece. Transaction details: USA sales preferred. Sent FedEx tracked, well packed; 2X boxed. Shipping is extra from 19380. Shipping overseas will be expensive, and buyers from abroad must pay via PayPal Gift. For USA, any payment form is OK, but bank checks and MOs must clear first. I have overall more than 1,000 transactions for tubes and tube gear on Agon and Ebay and HeadFi and here--all perfect. Buy with confidence. Thanks all.
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