[OctavianH]

I had a feeling they wouldn't work, just hoping I could finally use my little stockpile of odd tubes. Thanks for the reply, I think you're right on the compatibility.

If you have many 12SL7 maybe it makes sense to obtain a pair of 12SL7->6SL7 adapters with external heaters powered for 12.6V. They are like normal adapters but heaters are connected to an external power supply which has to provide 12.6V for them.

 

[L0rdGwyn]

Ok I'm very novice when it comes to tubes and compatibility, so be gentle with what's probably a very stupid question. Can12BH7A or 12SL7 tubes be run with adapters on the Aegis? I ask as I've got a decent stash of them from other amps I've since retired, but held on to all the tubes I bought for them. I honestly have no clue what I was running 12SL7 on, I just have a stash. But the 12BH7A were excellent sounding power tubes on my old Kenzie Ovation.

I think I am the bringer of bad news but these tubes were used at 12.6V heaters on your Kenzie Ovation. While 12SL7 cannot work on Aegis which has 6.3V heaters, the 12BH7A can be configured via the adapter for 6.3V (parallel) but even in that case I would not put a 3.5W plate dissipation tube on output on Aegis. Maybe you obtain some adapters for 12BH7A -> 6SN7/6SL7 and use these in input since they are double triodes, but even in this case the amplification factor of 16.5 might not be suitable for Aegis input stage (see what @L0rdGwyn said here about gain). And yes, wait for the advice of more experienced, I just tried to warn you not to try those before prior approval.

PS. I am no Aegis owner, just tried to help. Take my advice with a grain of salt.
PS2. Some tubes can work via adapters with external power for heater, that is another discussion.

Yeah, 12SL7 and 12BH7 are not compatible. Like @OctavianH said, you could use an adapter with an external power supply for 12SL7 if you'd like, but probably more trouble than it's worth. You can get pairs of NOS 6SL7 for very reasonable prices.

Another tube that can be adapted is the 7F7, which is a 6SL7 with a loctal base. They are pretty uncommon though, much less common than 6SL7.

 

[TheAbyss2022]

I've been wondering the same thing, but the Aegis with the Yggy A2 at Canjam NYC in the ZMF room sounded phenomenal. I don't recall if it was connected directly with RCA, or some sort of XLR to RCA conversion but maybe someone else can chime in. It was definitely the best sounding combo of any DAC and amp I've heard.

interesting as I did not know you can get RCA to XLR cables so this should work nicely when connecting it to my DAC.

 

[Wes S]

interesting as I did not know you can get RCA to XLR cables so this should work nicely when connecting it to my DAC.

I think you will need a converter box, and both RCA and XLR cables to go with it.

 

[L0rdGwyn]

interesting as I did not know you can get RCA to XLR cables so this should work nicely when connecting it to my DAC.

If using XLR to RCA cable, you are essentially just not using half of the balanced signal, making it single-ended. The DAC output voltage will be half of the fully balanced output. And it is very likely the same process is taking place from the single-ended outputs of the DAC. So using an XLR to RCA cable vs. just using the RCA outputs is essentially the same result.

 

[Wes S]

If using XLR to RCA cable, you are essentially just not using half of the balanced signal, making it single-ended. The DAC output voltage will be half of the fully balanced output. And it is very likely the same process is taking place from the single-ended outputs of the DAC. So using an XLR to RCA cable vs. just using the RCA outputs is essentially the same result.

Interesting, and I did not know there was such a cable.

 

[L0rdGwyn]

Interesting, and I did not know there was such a cable.

Well going XLR to RCA there is a cable, RCA to XLR is a different matter. You can get a single-ended signal from a balanced output, but you cannot get a balanced signal from a single-ended output.

 

[khaine1711]

Another tube that can be adapted is the 7F7, which is a 6SL7 with a loctal base. They are pretty uncommon though, much less common than 6SL7.

I've been using 7F7 for a while; very nice neutral sound; pretty darn cheap too, the 7F7 > 6SL7 adapter cost more than my pair ... Another input tube that can be adapted is 6c8g, I've seen many RCA clear glass 6c8g for cheap, while the tung sol black glass one costs as much as a good pair of 6sl7.

 

[Wes S]

The staging with this amp is flat out incredible. I love everything about this thing!

 

[L0rdGwyn]

I've been using 7F7 for a while; very nice neutral sound; pretty darn cheap too, the 7F7 > 6SL7 adapter cost more than my pair ... Another input tube that can be adapted is 6c8g, I've seen many RCA clear glass 6c8g for cheap, while the tung sol black glass one costs as much as a good pair of 6sl7.

Yeah 6C8G should work with an adapter, it is much like a 12AY7. But I have not tried this tubes or measured them in ZMF Aegis, so YMMV. My advice is to stick to 6SL7 at the get go, then if people feel inclined to get adventurous later, you try some of these adaptable input tubes. Anything lower gain than 6SL7 will limit peak power output. The limitation as far as bias current is related to the anode chokes; the input tubes must bias at low current so as to not saturate them. So any adapted tube must be high gain and low current. A tube like 12AX7 has a higher plate resistance than a 6SL7 and may negatively impact frequency response. So 12AY7, 12AT7, 6C8G, 7F7, 6SC7 are all probably a better choice for using adapters.

 

[WarrenS]

The staging with this amp is flat out incredible. I love everything about this thing!

This is not helping me resist temptation!

 

[Wes S]

This is not helping me resist temptation!

To resist is futile!

 

[TheAbyss2022]

If using XLR to RCA cable, you are essentially just not using half of the balanced signal, making it single-ended. The DAC output voltage will be half of the fully balanced output. And it is very likely the same process is taking place from the single-ended outputs of the DAC. So using an XLR to RCA cable vs. just using the RCA outputs is essentially the same result.

Would a converter box resolve that issue? and can I just buy any converter box or do higher priced units have better performance?

 

[JeffMann]

I have noted that Wes has a pre-production model where the paintwork on the transformers have a lot of turquoise (bluish-green) color mixed with brown and black. Do the post-production models that will become available for sale soon also have this turquoise color?

Another question. I am presently using a Cayin HA300MK2 amp to drive my Meze Empy Elite headphone. I own many different brands of CV6/7193/6C8C types of driver tube to drive my WE300B output tubes, but they all make the sound too thin and bright for my taste with an insufficient amount of warmth and tonal density in the midbass and lower midrange area. Would the Aegis headphone amp be better, or worse, from this perspective?

Jeff.

 

[L0rdGwyn]

Would a converter box resolve that issue? and can I just buy any converter box or do higher priced units have better performance?

I don't think there's really an issue to be resolved. Using the XLR to RCA cable is likely the same as using the RCA outs. A balanced output typically has a higher voltage output relative to single ended as there are two amplifying devices, the purposes is to cancel common mode noise. Because there are two amplifiers, you also get a higher output impedance, sometimes even higher distortion. Usually the balanced out is taken to sound better, but that's because it is louder. When level matched, it's likely the sound quality is the same. But if you wanted to convert the balanced to single-ended without the cable method, a transformer is one way to go about it. But you are adding a reactive component to the signal path to achieve that, which probably isn't worth the result IMO.

My suggestion for people who have DACs that have both RCA and XLR outputs is to use RCA outputs for single-ended amplifiers and XLR outputs for balanced amplifiers.