I don't know if I can take anymore, as I can't stop thinking about the last one.
L0rdGwyn's DIY Audio
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The chassis for this amp just arrived today! Had to put them together after work.
The lighting is poor, so you can't really tell in the photo, but the side panels are a very deep, dark green. The smaller of the two chassis is for the autoformer volume control, the larger for the amplifier.
A separate chassis for volume control! Wow, this must be next level.The chassis for this amp just arrived today! Had to put them together after work.
The lighting is poor, so you can't really tell in the photo, but the side panels are a very deep, dark green. The smaller of the two chassis is for the autoformer volume control, the larger for the amplifier.
I can't wait to see this one completed.
So basically it’s a headphone power amp with a passive preamp!
Exactly! The autoformers go from -52dB to +5dB, so they actually can provide some gain at the top of the volume dial.
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whirlwind
Headphoneus Supremus
This will be a fun build!
It will be nice to see those beautiful HY69's in an amp.
I could not tell the chassis was a dark green, it kind of looks gray, but after clicking on the pic, to make it bigger, it is much easier to see.
It will be nice to see those beautiful HY69's in an amp.
I could not tell the chassis was a dark green, it kind of looks gray, but after clicking on the pic, to make it bigger, it is much easier to see.
A separate chassis for volume control! Wow, this must be next level.
I can't wait to see this one completed.
Me too, going to start this weekend but have some stuff going on so not likely to finish it. This is a somewhat weird amplifier, I'm optimistic about the result, but never seen something like this before, so we'll see. Overall, the circuit is much like Aegis, but interstage transformer coupled and using directly heated pentodes as opposed to indirectly heated. And an autoformer volume control as I mentioned.
I had extensive discussion with Dave Slagle on what I needed for the output transformers for this build. A first time request for him, but ultimately he nailed it down. 6.5K primary and 300ohm, 75ohm, and 16ohm secondaries. The primary DCR is 360ohms, so no added series resistance needed for biasing. With a 300ohm B+, the HY69 will bias around 60mA. The output transformers are rated for 2W peak output, 18H primary inductance at 60mA. Based on my models and the cathode impedance of the HY69 as a cathode follower, will achieve roughly 6:1 damping ratios at those secondary impedances, so this amp should be able to drive just about any headphone.
miketlse
Headphoneus Supremus
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Yes, I could see the green tinge on the top edge of the side panels, but the panels themselves looked grayish.
miketlse
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I think you are fighting the tendency of phone cameras etc, to adjust images according to 'average criteria'.
Absolutely and in low light. I'll take other photos with a real camera.
I got some parts mounted, I think the green is easier to see in these photos, it gives you an idea of where things are going aesthetically. I wanted the amp to look very DIY, I call it "tastefully mismatched".
miketlse
Headphoneus Supremus
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Sorry, but that is a very vague green.I got some parts mounted, I think the green is easier to see in these photos, it gives you an idea of where things are going aesthetically. I wanted the amp to look very DIY, I call it "tastefully mismatched".
Sorry, but that is a very vague green.
It still looks washed out in the picture, looks much better in person. This is another phone picture because...I'm lazy lol pics of the completed amplifier will be taken with my Fuji.
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