I was thinking of your setup since the morpheus is basically a Dac/ preamp, I’ve pretty much set the volume knob on the Bigger Ben and left it there. Mainly because I’m too lazy to get up to adjust the volume on the amp when the Morpheus has a remote.
But it made me think “one less thing in the audio chain”
2 Likes
Cool! Being able to choose between an active and passive preamp suits me where I use the Mogwai SE for both headphones and speakers (with powered subwoofer).
I’ll keep you posted. In the past, I’ve preferred headphones without the MZ2, but that was primarily with the more highly revealing Verite Closed. The HD6XX is less sensitive even if not reflected in the specifications.
I’m a chronic optimizer and am aware! I’m not so lucky. Even if the noise went away, I prefer the more controlled presentation of the 32 and 8 ohm outs. The 300 ohm out is a candidate for instrumental and more mellow genres for me.
It’s nice that the Morpheus has a preamp and remote functionality. I used to have a Topping DAC with built-in preamp. I got better sonic results by deactivating the preamp and using it as a DAC only; you may have more success with the elevated Morpheus and Bigger Ben.
I’m generally a proponent for simplifying the audio chain and signal path, but have found that the Mogwai SE benefits from an active preamp with speakers (and most recently the HD6XX while running the lowest power/gain tube roll and DAC output voltage). The difference is subtle and we sometimes make a big deal of things. I trust Justin’s builds and am pretty sure that similar enough performance can be reached without a separate preamp by optimizing the tube roll and/or power supply management.
10 Likes
This morning’s listening was without the MZ2 and the afternoon was with the MZ2. If the differences were smaller, I’d celebrate being able to sell the MZ2. However, the enhancement with the MZ2 using headphones is more significant than I recall. Previously, I mainly used the Verite Closed, which fared better without the MZ2. I suspect the HD6XX is not revealing or sensitive enough such that the MZ2 can successfully be introduced to the signal path.
While the MZ2 is a tube preamp, it avoids sins of commission and unwanted coloration likely due to its push-pull OTL design and linear power supply. Besides being an active preamp, there also is the impact on impedance matching where the Qutest’s output impedance is 0.025 ohms, the MZ2’s is 2 ohms, and the Mogwai SE’s input impedance is 10k ohms.
Most sonic elements are elevated to my ear: clarity, resolution, black background, longer decay, larger sonic images, more discernible imaging and layering. The HD6XX’s and Mogwai SE’s native tonality, timbre, tonal density, speed, dynamics remain unaffected.
In comparing the HD6XX to the HD800 SDR mod, with this configuration, the latter still prevails in detail retrieval, soundstage, speed and general technical performance. However, the more balanced tonality of the HD6XX may be preferred for certain/most genres.
I generally hold that the simpler the system and signal path, the better. However, Justin did mention during discussions of my build that the Mogwai SE could benefit from some additional gain being introduced by an active preamp.
I’m uncertain about how close an active preamp and Mogwai SE chain gets to the performance of the Bigger Ben or Rockwell. I’d suspect the higher tier amps with larger output transformers and overall elevated builds will still prevail. However, it is possible that adding an active preamp to a chain with the Bigger Ben, Rockwell, Kenzie Ovation, or Nautilus may elevate such amps even further. It would be nice to confirm.
3 Likes
I agree that adding an active preamp will most definitely change the sound. whether that coloration or change is good or bad is really up to the exact situation and components picked. If you changed out the mz2 for something like a Shindo preamp you would be in very natural musical heaven but would ultimately lose some of that clarity you find with the mz2.
I plugged my mogwai into my LTA VTL 5.5 Signature 2 and got a very very warm tubey sound after adding a tube dac, used the external all tubed phono pre
and that warm tubbiness dialed up even higher. I used the mz2 after and also got a exact opposite with a more smoothed out detailed clarity to the mogwai.
It would be safe to assert that the other amps with similar circuitry like the BB and Nautilus would have very similar characteristics given each preamp selected.
This brings up the question of why does headphone audiophiles prefer integrated amps with very simple external preamps inside versus 2 channel audiophiles that most likely climbs up the upgrade ladder to separate components selecting external active preamps?It seems in the headphone world that they tend to love to externalize the power supply but keep the rest very simple and not go down the rabbit hole of mono blocks and separate pre’s.
I think its really cool how you built your mogwai because the sky is the limit to directing how you want your sound, based on what type of preamp you want. something like the Freya would be fun so you have both directions all in one.
For some fun, I would think going to a local hifi shop like upscale audio and doing an in house demo (if they do such a thing) of a full function tube preamp and a solid state preamp and see what your boundaries are in selections
5 Likes
Interesting findings and good observations!
I agree. With the Verite Closed, I preferred sonics without an active preamp.
Thanks, with the right headphones/speakers and electronics, my custom Mogwai SE should reach its full potential.
While I don’t see a need to move on from the MZ2, I’m inevitably brainstorming about options: Freya +, Freya S, PrimaLuna, Spring 3 with built in preamp, TT2 with built in preamp, Parasound, Elekit TU-8500, Bryson BHA-1’s preamp, GS-X Mini’s preamp. I need to remember to check myself and consider the inflection point for cost where it would be more favorable to move on from the Mogwai SE and get a better tube amp.
3 Likes
And the countdown begins… 
Had the extreme pleasure of meeting Justin on the phone today and ordered up the Nautilus. We’re going to be running this with the Rad-0, ZMF VCs, and a set of older La Scala speakers.
13 Likes
Congrats! Welcome to the Nautilus family, joining me and @Roikyou. I hope you enjoy it as much as I do.
The stock tubes that Justin provides are very good, but I have to say I wasn’t a big fan of the stock JJ 12ax7. I ended up replacing it with a 12au7 to lower the gain. Hopefully you like the JJ tube and also don’t need to reduce the gain, in which case you’ve saved some cash on tube rolling.
8 Likes
Congrats! It’s nice to see the proper full deployment of his amps for speaker duties as well.
By chance, did you guys discuss how the sonics of the Nautilus compares to the Rockwell?
4 Likes
We sure did! I was trying to decide between the Rockwell, Bigger Ben, and Nautilus. My takeaway was that the Bigger Ben and Nautilus offer a similar “more balanced” sound signature and the Rockwell is a bit more colored. The Rockwell can take some pretty old tubes if that’s your style. I personally made the decision less on sound and more on the available tube options. The Bigger Ben and Nautilus run a ton of tubes. I’m sure they all sound great and the subtle sound differences probably don’t matter that much if you don’t have multiple amps right next to each other to compare.
7 Likes
Awesome! I have a Mogwai SE and use it for both speakers and headphones. I would agree that the Bigger Ben/Nautilus (same family based on power tubes) are “more balanced” and versatile with many tube options. The Rockwell’s sonics interest me as it uses directly heated power tubes; I’m not aware of any impressions out in the wild other than Marcello’s introductory livestream. The Nautilus may also be a better choice for someone needing the additional power to drive speakers (and planars). I’m waiting for a RAD-0 myself.
6 Likes
Are there any amps in their line up that do not encounter noise issues such as transformer hum, ground loop, and antenna like sounds?
I recall the Pendant, and Mogwai have these especially with the High Z outputs of 300 ohm, and 100 ohm.
2 Likes
My Kenzie Ovation is very very quiet. No pops, squiggles, hum, or other odd sounds my OG and SE Pendants produce. It’s one of the quietest tube amps i’ve used.
3 Likes
Thanks, so why is the Kenzie ovation quiet, does it have the 300/100 ohm taps too?
2 Likes
The why is definitely a question for Justin, the tech of amps is way above my head. I know the 1626 tubes it uses are fairly low in power, and from what I’ve read about the other models, seems like as the output power increases, so does the noise. The Ovation is pretty sick, it has five impedance taps, 8, 16, 32, 100, and 300. All are very quiet thankfully, even 100/300. Comparing the 100ohm taps on the Pendant SE and Ovation, the Ovation is much quieter, with no hum or popping or anything noticeably broadcasting. The Pendant has a low level hum and occasionally makes some odd squiggle sounds, especially with my phone anywhere near it. It seems pretty sensitive to my monitor as well. I’ve raised it up very high off the desk with a long arm mount, and that has helped. But overall the Pendant is the noisier of the two by a large margin. That being said, it’s not horribly noisy to me. The noise floor is low enough that even with the VC, it’s easy to ignore. It’s a huge improvement over my early gen OG Pendant. That thing was very noisy.
3 Likes
I guess that is where I find any noise not easy to ignore, especially on any amp that is over $2k. I was also using the VO and at 300 ohm and 32 ohm the noise was very present, especially during softer passages of music.
So essentially the Kenzie Ovation would be the amp to go with if one wants a dead silent background?
2 Likes
I’ve not heard the other iterations of the Kenzie (OG and Encore), those might also be quiet. But yes, from my limited experience the Kenzie Ovation is the only ampsandsound amp that’s been completely quiet.
3 Likes
I went back through and read some of the previous posts. Found this post on the Ovation, he seems to experience a similar noise issue:
Now that leave my head scratching a bit more, inconsistent findings…
A lot of the issue can be the environment the amp is in.
I had similar issues with my pendant, nothing I tried addressed the background noise on the high impedance tap, I just stopped using it.
I sold the amp, the guy who bought it has no noise through a Verite on either tap, same amp, same tubes, different environment.
I think Justin’s amps just tend to be prone to environmental noise.
I’ve got 7 other tube amps here from a few hundred mW to 135W Monoblocks and none of them have the background noise issue.
I just wish I could have tracked down the root cause in the environment.
3 Likes
I had Auris amps before A&S. They didn’t have the static in the phone line as I like to call it or hum from the power supply but were susceptible to ground loops. So power issues outside the amps were big issues. The power supply was separate and could be kept under the desk, plus they were sealed, so they were quiet. (I’ve mentioned in the past where the Mogwai SE is noisier than the Bigger Bigger, the Bigger Ben is noisier than the Nautilus, which is the most quiet of the bunch I’ve used and it’s transformers are sealed behind steel) My point, I bet every amp has some kind of issue and I bet all have some kind of vulnerability to power issues and if dirty power is common, which I guess it is, how do you control it from the street and get good, clean power from the street? And filter noise from throughout your house from being amplified in these amps we use? Just my thoughts from listening to people, vendors and owning these amps, amps I’ve passed on to other people who have had issues with these amps where I have no. Again, my two cents.