After a few weeks burn-in period of this little beast, I found it's very relaxing to listen to. I can hear more juices coming out and the STAX 009 just doesn't have that analytical sounding cliché to my ears. It also enhances the soundstage and life-like of Focal Utopia makes it way more enjoyable to hear.
This is a push-pull design tube Headphone Amplifier/Preamplifier attempting to achieve the true high-performance of headphones from Dynamic, Planar Magnetic to Electrostatic models.
I've gotten a few PM's asking about the schematics and stuff so I decided to open a thread to discuss more here.
a few interesting measurements of the amp at R = 6Ω
DT-HWT Headphone Amplifier/Preamplifier schematic:
DT-HWT Power Supply schematic:
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Inputs – it has two sets of RCA inputs.
Output – it has different outputs, provided on a number of different connectors. On the amp front is a TRS ¼” unbalanced jack, and balanced headphone outputs on a single 4-pin XLR and a pro bias 5-pin Stax headphone jack. On the amp rear, there are two sets of 3-pin XLR and RCA preamp outputs. Both sets can be used at the same time if desired – for example, you could feed a power amplifier from the XLR connectors, and a subwoofer amp from the RCA connectors.
The bias voltage settings on the separate power supply unit are used only with electrostatic ear speakers (> 100K Ω impedance). You can select whichever bias level sounds better to your STAX/HE90 models from 230-500-580 up to 620 V DC bias.
Tube complement for the amp unit is: matched pair of EF86/E80F/6D8 & matched pair of 12AU7/5814A/E80CC/E82CC & matched quad of EL95/6AQ5
Tube complement for the power supply unit is: matched pair of KT66/KT77/KT88/6550/6L6/EL34/350B/350A & one 6080/5998/6AS7/6H13C/2399
Look forward to those next iterations/variants from you guys soon... For the meantime, I keep on rolling 11 tubes to find the best combination that suits best for different music genres