Now it’s the longest 4-7 day wait ever! I remember when my eikon stalled for a day or two just outside San Diego, I was going crazy!
Aegis DIY Tube Headphone Amplifier
- Thread starter L0rdGwyn
- Start date
Someone on diyAudio pointed out that the 100ohm carbon composition grid stoppers are no longer available on Mouser. I will update the BOM and make a substitution. Unfortunately, it seems carbon composition resistors are falling out of favor with commercial resistor manufacturers. Due to the properties of their construction, they are innately non-inductive and make good grid stoppers. More important for high gm tubes, a 6SL7 is not very likely to have any issues with oscillation, so a substituted carbon film will do just fine.
funch
Headphoneus Supremus
Here's a source for carbon comp resistors: https://www.tubesandmore.com/products/resistors
funch
Headphoneus Supremus
I was wondering what paint that is. It would be perfect for a project I'm re-casing in a Landfall chassis. Thanks.Thanks! It’s a dark green that looks almost black. But under sunlight / room lights then it sparkles a bit
Its called forest sparkle. I mentioned to Dave that I was keen on a dark green and he suggest this. I love how it turned out.
I was taking some measurements of Aegis today when I realized that I had made an error in the build instructions. The intention of the circuit is to maintain absolute signal polarity from input to output. This is done by wiring the primary and secondary of the output transformer in opposite polarity since a cathode follower stage is non signal inverting. However, as built, this is not the case, I wrote the instructions to wire the output transformer primary and secondary with the same polarity by mistake. The audibility of absolute signal polarity is debatable, but it is very simple to fix, so here is what you need to do.
1) If you are thinking about building this amplifier or are acquiring parts but have not yet ordered the ELMA switch PCB, I've uploaded a new PCB gerber file to the diyAudio page. The error is corrected on the new PCB and the instructions can be followed as written.
2) If you've already built or own an Aegis, or have already ordered the old ELMA switch PCB, you will need to do the following.
- Find the screw terminal where the output transformer wires (pins 13 and 18) connect to the main PCB. Loosen the screw terminals and flip the wires such that the red wire (pin 18) goes to the negative (-) screw terminal and the black wire (pin 13) goes to the positive (+) screw terminal. Retighten the screws. Repeat the process for the other channel.
That's it, then the polarity is corrected. As I mentioned, the audibility here is very questionable. I A-B'd in both orientations with alligator clips. I thought maybe the corrected polarity sounded better, but honestly in a blind test I'd never be able to tell them apart. It's just a matter of principle as this was how the circuit was supposed to be built.
Anyway, sorry for the inconvenience, hope it isn't too much of a hassle to do this flip flop. As I said, with the issue corrected on the new ELMA switch PCB, any build going forward can simply follow the original instructions. If you have the old ELMA PCB but have not built yet, you will need to do this fix as well.
1) If you are thinking about building this amplifier or are acquiring parts but have not yet ordered the ELMA switch PCB, I've uploaded a new PCB gerber file to the diyAudio page. The error is corrected on the new PCB and the instructions can be followed as written.
2) If you've already built or own an Aegis, or have already ordered the old ELMA switch PCB, you will need to do the following.
- Find the screw terminal where the output transformer wires (pins 13 and 18) connect to the main PCB. Loosen the screw terminals and flip the wires such that the red wire (pin 18) goes to the negative (-) screw terminal and the black wire (pin 13) goes to the positive (+) screw terminal. Retighten the screws. Repeat the process for the other channel.
That's it, then the polarity is corrected. As I mentioned, the audibility here is very questionable. I A-B'd in both orientations with alligator clips. I thought maybe the corrected polarity sounded better, but honestly in a blind test I'd never be able to tell them apart. It's just a matter of principle as this was how the circuit was supposed to be built.
Anyway, sorry for the inconvenience, hope it isn't too much of a hassle to do this flip flop. As I said, with the issue corrected on the new ELMA switch PCB, any build going forward can simply follow the original instructions. If you have the old ELMA PCB but have not built yet, you will need to do this fix as well.
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Seems a simple and straight forward fix. But I am going to expect night and day differenceI was taking some measurements of Aegis today when I realized that I had made an error in the build instructions. The intention of the circuit is to maintain absolute signal polarity from input to output. This is done by wiring the primary and secondary of the output transformer in opposite polarity since a cathode follower stage is non signal inverting. However, as built, this is not the case, I wrote the instructions to wire the output transformer primary and secondary with the same polarity by mistake. The audibility of absolute signal polarity is debatable, but it is very simple to fix, so here is what you need to do.
1) If you are thinking about building this amplifier or are acquiring parts but have not yet ordered the ELMA switch PCB, I've uploaded a new PCB gerber file to the diyAudio page. The error is corrected on the new PCB and the instructions can be followed as written.
2) If you've already built or own an Aegis, or have already ordered the old ELMA switch PCB, you will need to do the following.
- Find the screw terminal where the output transformer wires (pins 13 and 18) connect to the main PCB. Loosen the screw terminals and flip the wires such that the red wire (pin 18) goes to the negative (-) screw terminal and the black wire goes to the positive (+) screw terminal. Retighten the screws. Repeat the process for the other channel.
That's it, then the polarity is corrected. As I mentioned, the audibility here is very questionable. I A-B'd in both orientations with alligator clips. I thought maybe the corrected polarity sounded better, but honestly in a blind test I'd never be able to tell them apart. It's just a matter of principle as this was how the circuit was supposed to be built.
Anyway, sorry for the inconvenience, hope it isn't too much of a hassle to do this flip flop. As I said, with the issue corrected on the new ELMA switch PCB, any build going forward can simply follow the original instructions. If you have the old ELMA PCB but have not built yet, you will need to do this fix as well.
I was reading the post and he mentioned the elma switch and my first reaction was, "NOOOOOoooooooooooooooo I don't want to solder a new elma board!!!!"
I think I can handle flipping these unsoldered wires. It gives me an excuse to test the readings on the 6889 tubes anyway, which I've been putting off.
I think I can handle flipping these unsoldered wires. It gives me an excuse to test the readings on the 6889 tubes anyway, which I've been putting off.
I've adjusted the Amps section of my signature line to reflect this information.
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Listen to the amp BEFORE the change, and make sure it is after 6pm but before midnight.But I am going to expect night and day difference
After the change, wait until 7am and listen again.
I promise NIGHT and DAY difference!
So I literally begun the journey yesterday and I will not be using the Elma switch as posted before, @L0rdGwyn no change in the instructions in this post: https://www.head-fi.org/threads/aegis-diy-tube-headphone-amplifier.965530/post-17596500 ?
Main pcb board ready, got all parts except the chassi plates from a local laser cutting shop, hopefully get them next week, though then powder coating at a different shop…
Main pcb board ready, got all parts except the chassi plates from a local laser cutting shop, hopefully get them next week, though then powder coating at a different shop…
Last edited:
Toonartist
Formerly known as dAndis67
Ok… small fix but it’s a good job I know someone who can do these things… he should be around later today. I better buy in a couple of beers as paymentI was taking some measurements of Aegis today when I realized that I had made an error in the build instructions. The intention of the circuit is to maintain absolute signal polarity from input to output. This is done by wiring the primary and secondary of the output transformer in opposite polarity since a cathode follower stage is non signal inverting. However, as built, this is not the case, I wrote the instructions to wire the output transformer primary and secondary with the same polarity by mistake. The audibility of absolute signal polarity is debatable, but it is very simple to fix, so here is what you need to do.
1) If you are thinking about building this amplifier or are acquiring parts but have not yet ordered the ELMA switch PCB, I've uploaded a new PCB gerber file to the diyAudio page. The error is corrected on the new PCB and the instructions can be followed as written.
2) If you've already built or own an Aegis, or have already ordered the old ELMA switch PCB, you will need to do the following.
- Find the screw terminal where the output transformer wires (pins 13 and 18) connect to the main PCB. Loosen the screw terminals and flip the wires such that the red wire (pin 18) goes to the negative (-) screw terminal and the black wire (pin 13) goes to the positive (+) screw terminal. Retighten the screws. Repeat the process for the other channel.
That's it, then the polarity is corrected. As I mentioned, the audibility here is very questionable. I A-B'd in both orientations with alligator clips. I thought maybe the corrected polarity sounded better, but honestly in a blind test I'd never be able to tell them apart. It's just a matter of principle as this was how the circuit was supposed to be built.
Anyway, sorry for the inconvenience, hope it isn't too much of a hassle to do this flip flop. As I said, with the issue corrected on the new ELMA switch PCB, any build going forward can simply follow the original instructions. If you have the old ELMA PCB but have not built yet, you will need to do this fix as well.
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