mwhouston

Sharp eye Red.

Our blockers are quite different and therefore the pricing difference. Doesn’t necessarily make one better better than the other. I’m happy though mine have worked on the situations they have been used for.

Used these before and the others (PIO). Both with really excellent results. And often such a cheap purchase.

Teflon?

These have been sitting in the da lab for years. Only a few hours of use. Such a shame to have such nice matched tubes (Psvane 12AU7 T series MKII gold pin) unused and not playing music. I have all the parts. Time to make a SRPP preamp with these fine specimens.

Further information: This 233gm DIY portable headphone amp runs on four AAA batteries or AAA rechargeable for about 30 hours of play. More time with better batteries even Lithiums. In two tone ABS and matching knob looks smart and is durable. Perfect travel companions for music on your phone or steaming via the phone. At home will work with any audio source. The HP amp drives 32 and 250ohm headphones to loud levels and an easy to adjust volume. It employs “safe on” which means unless there is a source plugged and and it is turned on no power flows. Meaning it is harder to inadvertently leave on. There is an low level on led light and battery test point. No need to open to test batteries. Battery change only takes minutes and is achieved buy four easy access screws. The chip used is the dedicated PT2308 headphone driver chip which has a very low distortion and excellent drive capability. Because of battery operation the amp is dead quiet, has deep bass response and sounds excellent. The enclosure is Al lined for shielding. http://retro-thermionic.blogspot.com/2019/06/i-have-been-using-oatley-k272c-kit-in.html Photos:

An interesting observation and consideration when making preamp which use low gain tubes or low power power tubes is the gain. Sounds obvious but until you compare a preamp with a high gain tube like a 12AX7 or 6SN7 it may not seem a consideration. With the four preamp I made with high gain tubes a two step volume increase, with my 24 step stepper pot, would give a noticeable increase in volume. Let’s say 2db. But with my 71A 1920s tube based preamp I have to make four steps (four clicks) to get near the same increase or decrease in volume. Two clicks almost has no effect. Though low in gain there is just enough drive and gain to get full power out of any of the powers amps, SS or tube. I just have to keep in mind I have to make big adjustments on the volume knob to get the level I want. Thank the audio God the preamp sounds so good. And maybe that’s because I’m using a low power DHT to do the pre work. https://retro-thermionic.blogspot.com/2020/04/mwh-1920s-ux-171a-tube-preamp.html

Not my system but one from many audio groups on a member of in FB. Being a horn owner it appeals But way too big for lounge room listening.

Pro. finish.

Qwazy.

Qwazy, do it.

Wouldn’t take much to drive them.

OK, except for the price shock I'm impressed to. Sensitivity rating of the speakers?

You hear so much more on headphones compared to even high end Systems/speakers. Reason is there is no room nodes etc getting in the way and the audio is pumped directly into your ear canal and brain. Easier to pick head amp/headphone differences than open system differences. But is is all a compromise, gain something here lose something there. I love my Holton/horn setup but melt when I put in my 2W 6L6 SE UL wine box amp and Beyma 12” concentrics in. Yes I lose bass extension but I gain a depth and natural “take you there” experience. It’s all a compromise. Enjoy each system/component for what it has to bring not what it can’t do. Bit like humans really!

Need a better image. Try some more shots.