Aegis DIY Headphone Amp

Saw a DIY and ZMF Aegis at the last Head Fi So Cal meet.

Edit: I believe @theveterans owns the first one.

 

So far only NOS Sovtek 6SL7, new production EH EL34, and a new production Sovtek 5AR4.

I figured Sovtek was a safe bet for some starter tubes as I enjoy them on my Stratus as well (5U4G and 691P-EV.).

I appreciate your posts and tube impressions. I will most likely try and score similar NOS tubes as far as the rectifier and input tubes go. The possibilities are overwhelming with this amp.

 

I settled with the Tung Sol 6SU7GTY, Tung Sol 7581A and Mullard GZ32 rectifier tube.

The DIY Aegis with this tube combo results to more neutral and airy signature focusing on fast transients when compared to the stock tubes (JJ El34 + JJ 6SL7) that the commercial ZMF Aegis comes with. Interestingly, when @insidious meme demoed the Aegis from High Z out using the VO, the sound became lush and intimate, and switching to Low Z mode, VO opened up significantly. The opposite is what I observed with Atrium Open where High Z out is more open sounding than Low Z out

 

Never heard an Aegis, but I can also recommend the 40’s RCA JAN 5R4GY. Really great tube in Studio B - warm and tooby but with a good stage/euphony and doesn’t sacrifice detail too much. Liked the 40’s double D getter better than the 50’s single D getter version (former is more tooby and throws a bigger stage/holography), but they’re both good.

 

The guy I bought my RCA JAN 5R4GY from said basically the same thing. He said the early double D getter version is the one to get. I tried 3 other rectifiers in my Aegis, but I always came back to this one.

I know too little about what a rectifier does to the sound to speak to why I prefer this 5R4GY, but it sounds “just right” to me. I expected to like the more-expensive Mullard GZ34, but it sounded a little more solid-state to me than this RCA. I also really dig the looks of the old coke bottle RCA rectifier tube!

As far as input tubes go, the 3 most popular choices of Aegis owners seem to be the RCA red base 5691’s, Tung-Sol 6SU7GTY’s and Mullard ECC35’s. I also like the 1940’s RCA smoked glass 6SL7’s. They are a bit warmer and tubey than the 5691’s I use most of the time.

 

Yeah I had come from a Fat Base 1959 Blackburn Mullard GZ34 in Studio B. Definitely more solid state. Good detail but it’s more anemic than the RCA and more linear. The RCA goes well with the other tubes I’m using though (Elrog 300B’s aren’t very tooby, needed more body), and I say that even as a guy who likes detail and sharpness over toobiness, generally.

I think the RCA is the oldest tube I’ve used. Was a trip to get it in the box with “Accepted April 1945” printed on it. Same month Hitler offed himself and Eva Braun. Feels like using a piece of history, lol.

 

You guys are the worst. Lol. Found a pair of 1940s double D getter RCA 5R4GY on the bay and said screw it. Only need one, but they were pretty damn cheap together.

Any advice on where to find a decent pair of RCA red base 5691? I see Brent Jesse has pairs for $200. Everyone else seems to be asking for more for used pairs on ebay, etc.

 

Sorry to be such a bad influence! I always check eBay, Reverb, Etsy, Brent Jessee, Vintage Tube Services, USAudioMart, and Head-Fi classifieds when I’m looking for specific tubes. Unfortunately, you never know where the best deal is going to be.

 

The 6L6GC (7581a is a 6L6GC type tube) power tube is one of my favorite tubes for the Aegis.

As you described @theveterans it's airy, more neutral (most of the other tubes like EL34s, KT66, and KT88 (which is more neutral than the rest but doesn't sound as open) are midcentric or warm).

Favorite driver tubes are the Tung-Sol black glass round plates 6SL7s. Keep going back to them even with some really nice NOS tubes.

 

Ok, so after extended listening I'm finding my current tube loadout to be a bit unforgiving and a bit harsh / fatiguing.

Switching back to Stratus was a breath of fesh air. But, I remind myself it took nearly 4 months of tube rolling to bring that amp to exactly where I wanted it. It could also be a bit much with bright or lean new production tubes.

I have a NOS loadout coming by this weekend that I hope will relaxe things a bit. Includes a 1940s RCA 5R4YG for rectifier, a pair of RCA 5691 red base for input tubes and a pair of Sylvania 6L6G for power.

I'll report back after I have time to listen / swap tubes around. Granted what I'm using now is on the very cheap end of NOS and new production so I'm not making any conclusions on this amp until I can hear a bunch more tubes in it.

 

If anyone has the 6V6 pentode and the 5Y3 rectifier, could you please try that combo and let me know what that sounds like? People also have been meme-ing the 807 tube.

 

One of my favorite combos is a Bendix 6106 with a pair of Fivre 6V6. Not the last word in detail and bass extension, but very enjoyable and organic.

I got a pair of Cossor 807, and they are very good.

 

Popped in a 1940 RCA JAN 5R4GY and this amp is on another level. Can't wait to get the other NOS tubes.

Compared to El cheapo Sovtek 5AR4 the amp is way more dynamic and hits like a truck. More ethereal sounding at the same time. Sounds more natural and correct, especially vocals. No harshness and I can crank the volume without discomfort.



Also finished shortening wires, cleaning up the routes and zip tying to tie downs today. Looks a hair cleaner.

 

Hell yeah. lol hopefully we don’t get some speculation going and the eBay sellers don’t jack up the prices on that tube, but there definitely is something to it. Brent Jesse I think is the one who started to hype it a bit, he compares it favorably in his stock list description to the WE 274B, which is one of the practically unobtanium WE tubes and goes for like 2k a pop. Anyway, glad it moved the needle for you. Toobs!

 

I personally love the GZ34 rectifier which is equivalent to your 5AR4. Makes the amp quick and solid state like. Hate to add another recommendation, not really, but if you decide you like the 5AR4, but need a power tube that is more forgiving, try out the KT66 from TAD or Genalex Lions. Great tubes that are warm.

 

Those 1940’s RCA JAN 5R4GY’s are the real deal. The fact that they are still priced reasonably is just icing on the cake. I liked it more than my Mullard GZ34 no matter what input and output tubes I rolled in the amp. I’m tempted to grab a back-up now in case they get too popular!

 

Ok boys, I went ham on input tubes from Brent Jessee, and also got some decent matching Sylvania 6L6GC power tubes on ebay.

Unsurprisingly the rectifier made the most difference by a long way. Input and output tubes in this combo still have the same amount of slam and bass, but there is an added refinement to everything. Top end is more airy and extended, which I'm totally into (Thanks to 6L6?).

Going to stay with this tube roll for a while as I can't really find anything I don't like. A bonus is the amp is quieter now. I suspected the Sovtek input tubes and can confirm they were the reason I would get some hissing occasionally and would have to give them a light "wtf bro?" tap occasionally to quiet down.

Thanks all for the tube recommendations! Especially on the rectifier.

Really not missing Stratus at all with this combo of tubes. This amp is absolutely exceptional. There are a lot of jaw dropping moments listening to old albums.

I know this amp has got the hype going but damn if it isn't warranted.

 

My Aegis is back in action! I ended up tearing it down while I waited for a professionally cut and powder coated top plate. I also got the same sturdy extruded aluminum panels for all 4 sides. The front and rear were previously a semi-removable thin section of aluminum that rattled a bit and was not very sturdy.

This thing is a solid hunk now and finally looks the part. (My attempt at drilling was ugly from closer than 6 feet).

A big thanks to @gaspasser for helping get the cad files sorted for this specific chassis.

Now it's time to sit back, tube roll and enjoy!

(Zeke helped supervise the build).

 

I’m in the process of building mine too! With the help of my wife who is awesome at AutoCAD and with the killer suggestion by @yotacowboy of using SendCutSend there is now a real alternative to Landfall for an excellent case for this amplifier. Please feel free to PM for the CAD files and information if needed. @RestoredSparda and I have been working in this for a while lol. Hopefully this amp is worth all of this, but all of the drilling aluminum was a good learning experience. A huge thanks to @yotacowboy for all of your wisdom, help and encouragement!

 

It’s been quite a journey but I finally finished this beast of a project which birthed a beast of an amp. I wanted to build this amp because after getting and enjoying the pentode-based Elekit TU-8800, I was looking for a reasonably priced headphone amp that utilizes these same power tubes.
The main problem with sourcing and building this amp this summer was the enclosure supplier (Landfall Systems) was shut down since the spring and just reopened and AFAIK aren’t even taking new orders yet. I learned a lot about buying and drilling aluminum enclosures and AutoCAD. The case work was not easy but thanks to help from @yotacowboy and @RestoredSparda I got it done.
I can’t say a lot about the sound yet other than this is definitely a big boi amp that drives my JAR600, JAR580 and KISS 6XX as well as anything from EC or DNA that I’ve owned or heard.