Congrats.
I describe my Mogwai SE as having authority over the driver and showing it who’s boss.
I’ve recently spent some time with the TT2. With the Mogwai SE, I preferred preamp mode/low gain over DAC mode.
4 Likes
I should know this, but I take it that when you put Hugo in preamp mode it still serves as a DAC? I will check but I believe I am using the settings you suggest.
3 Likes
yup, but adds volume control.
When it was feeding a Bryston BHA-1, I went back and forth on how I liked it. I still believe volume control should be done in analog, cause I am a dinosaur, but the chord seems to have it’s volume control scheme working really well.
It does run a little hot on the outputs in DAC mode, which may have something to do with preferring it in preamp mode.
4 Likes
I was thinking about something tonight in regards to the Nautilus as i listened. Two different analogies come to mind. Listening to the Nautilus is like reading a book next to a fireplace, there’s a warmth coming coming from that fireplace as you read your book. Another analogy is that the Nautilus reminds me of a classic muscle car, also gives off quite a bit of warmth with a lot of power as you enjoy the drive. Can you enjoy the drive in a Kia, i guess you could. All gets you there eventually.
1 Like
Hey everyone,
After nearly four months of living with the Mogwai OG with upgraded Jupiter caps, I thought I’d share my experience with it. I think I’ve finally achieved the magic “synergy” between my DAC, the Mogwai, and my Verite Closed headphones. I need to say that the journey wouldn’t have been as rewarding if I didn’t go through everything I did with tube rolling, and if I would have started out with an amazing DAC and high quality RCA cables. When I bought my Mogwai, the journey began with my humble Monolith 788 THX AAA Balanced Headphone DAC. I thought it would pair well with the Mogwai, and the dual AKM 4493 chips would provide a good balance of clinical detail along with the dynamic slam and warm sound of the amp. But the main reason I started with the 788 was because my finances were so drained after buying Verite Closed headphones and the Mogwai that I wasn’t able to upgrade my DAC for a while.
Following Justin Weber’s advice, the first thing I did was look for a U.S. manufactured NOS input tube as an upgrade over the stock JJ 6SL7 tube that came with the amp. I bought a WWII era Sylvania 6SL7WGT VT-229 input tube for $79. From the moment I popped it in, I was disappointed with how the sound changed from a warm tube sound to a very sterile (almost clinical) sound. I did enjoy the enormous sound stage with the VT-229, but I was really unhappy with the cold sound. I swapped the Sylvania tube to a NOS RCA 6SL7GT, and it sounded okay, but the RCA tube was noisy, and it got much worse as it broke in. I returned the RCA tube and at that point, I remember questioning whether it was worth buying another input tube as the two more expensive input tubes didn’t beat the sound of the inexpensive JJ 6SL7 tube, and it was dead quiet. I decided to spend a little more and bought a Tung-Sol 6SU7WGT. Man, what a difference! The Mogwai immediately sounded so sweet and the vocals, pianos, and horns sounded vibrant and holographic. Best of all, like the stock JJ 6SL7 tube, the Tung-Sol 6SU7WGT was dead quiet too. It was a very big improvement in sound considering the $100 spent for the tube.
Next, I began the frustrating journey of buying KT88 power tubes. After everything I heard about how good KT88s sound in the Mogwai, I had to try them. The first pair of JJ KT88s purchased were microphonic and produced lots of ringing, even if I just lightly tapped my desk with a finger. I couldn’t touch my keyboard at all while listening to music, especially with the VC as they pick up everything. So I exchanged the JJ KT88s for another pair only to find the second pair making an annoying crackling sound that could be heard even when the volume was turned all the way down. I returned the JJs and ordered the Gold Lion KT88s (re-issue) with cryo treatment, which is suppose to help break in the tubes and weed out bad ones. I was so confident there would be no issues, but as soon as I plugged them in, I heard the same static and crackling noise coming from one side of the VC ear cups. I was so frustrated: I couldn’t understand why I had issues with three different pairs of KT88 tubes (from two different brands), and I began to think that maybe there was something wrong with my amp. After explaining everything to Justin, I drove my amp to him and he verified that it was indeed a bad Gold Lion KT88 tube. When the bad tube was switched from the right side to the left side of the amp, the crackling noise switched from the right ear cup to the left side. I’ve said it before and I’ll say it again: Justin is an amazing guy and his customer service is like no other. Thank you again for your help. So I returned the third pair of tubes and was about to give up entirely on KT88s. I remembered nearly giving up on the input tubes too before finding the 6SU7WGT, so I decided to try one last time and bought a pair of JJ KT88 tubes (from a different website) and guess what? There was no static or crackling. Yes, the KT88s make some noise as you can hear slight ticking as they heat up (kind of like the noise an iron makes when you iron your clothes), but it’s nothing like the static and crackling sound I was hearing with the previous sets of KT88s. My guess is that quality control is hit and miss with the two brands I tested.
As far as the sound on the KT88s: the sub bass rumble and dynamic slam is fantastic, and I really enjoy them most with EDM and Pop music. If you love slam and sub bass, the combination of the Mogwai and KT88s will put a huge smile on your face. In my opinion, the KT88s seem to produce a V-shaped sound emphasizing the sub bass and highs, but the the midrange and vocals (to my ears) seem slightly pulled back, except with the Audeze LCD-X, which really pairs well with the KT88s. But with the VC, I think the Tung-Sol 6L6GC STR power tubes that come stock with the Mogwai sound better and produce a much better balance of midrange, good bass, and an amazing euphonic sound that makes me keep coming back to them after hearing the KT88s for a few hours. The one critique I have about the Tung-Sol 6L6GC STR is that I wish I can have a little more detail in the highs without losing the tubeyness (if that’s a word).
After my birthday in May, I managed to put together enough money for a new DAC. And after watching lots of youtube videos and reading through reviews and posts on the forums, I decided to buy a Schiit Bifrost 2. As I waited the 8 weeks for the Bifrost to arrive, I followed Justin’s suggestion and bought Blue Jeans LC-1 RCA cables, which improved the dynamics and seemed to strengthen the lower frequencies of my old DAC. As soon as the Bifrost 2 arrived, I noticed a big difference in the sound. There is now a heft and weight behind each musical note, and as a result, the imaging on my VC seems better as instruments sound more separated. There is also even more dynamic impact of drums, bass, and piano notes. Even though some claim the Bifrost 2 is not as detailed as other DACs, the microdynamics are really standing out, and I can hear more detail than my clinical 788. Best of all, the timbre of instruments and human voices sound more natural in comparison to my old DAC.
And that leads me to the latest upgrade. I apologize for not remembering who suggested this or what forum I read it, but someone suggested that I email Zack from ZMF and ask him which tubes he recommends for the Mogwai. Zach responded by saying the Vintage RCA/Tung-Sol 6550 tubes sound amazing in the Mogwai. So I ordered original Tung-Sol 6550 squat “coke bottle” shape, brown base, smooth “no-hole” greyplates. Yes, they were expensive and came in a box labeled “1962” and the other one “1963”. I assume this is their production date. My Lord! These tubes are exactly what I was looking for…they are even more euphonic than the Tung-Sol 6L6GC STR and have much better midrange. OMG the vocals!!! Music is punchy and has a good amount of sub bass (not as much as the KT88s) but these vintage 6550s are not V-shaped, and the sound stage is HUGE!!! So far, these have more detail than any tubes I have heard and cymbals now have the sparkle to accompany the tube sound. Best of all, they are surprisingly very quiet.
I don’t know where to go from here, but I feel like I’ve reached an audiophile peak, and I need to just chill out with buying and just enjoy music for a while.
Here’s my current chain with pictures below:
Qobuz → iMac → Tripp Lite USB 2.0 Hi-Speed A/B cable → Bifrost 2 → Blue Jeans LC-1 RCA cables → AmpsandSound Mogwai OG with upgraded Jupiter Caps, Tung-Sol 6SU7WGT input tube, Vintage Tung-Sol 6550 “no hole” greyplates power tubes → ZMF Verite Closed (Monkeypod)/Audeze LCD-X/Sennheiser 6XX
-RayRod
23 Likes
Nice setup Ray. I’m using the Tung Sol black plates in my Bigger Ben and experienced a similar upgrade.
I’m using an adapter for the input tube to increase my options. Still haven’t quite settled on an input tube yet.
7 Likes
Congrats and nice setup. One thing to consider is a lower gain 6SN7 or 12AU7 (with adapter) input tube, which may play nicely with your KT88s.
4 Likes
That was a long enough break of not spending money on tubes.
bpcarb: Is there a specific 12AU7 input tube and adapter you recommend? 
2 Likes
Nice setup @Ray. I also use the “no hole” grey plate 6550s in my Nautilus.
Regarding your question about recommended 12au7’s, it’s so dependent on your sound preferences. Since each manufacturer has a little bit of a house sound, I’d recommend trying some cheap NOS 12au7’s to get a feel for what you want, before spending the big bucks.
If you like a bit of warmth in the mids, yellow label Baldwin tubes (made by Raytheon) are very good value for money at about $20 each. The green label Baldwins (made by Sylvania) are less warm, and even cheaper. I personally like warm mids without any roll-off in the highs, and graduated from the yellow Baldwins to Amperex and Brimar 12au7’s, with lots of help along the way from forum members.
Brent Jessee’s site is a good resource for the house sound of each manufacturer. I find Tube Maze to be very helpful if you need info on a particular tube. I also found this chart on the Steve Hoffman forum:
12 Likes
This 12AU7 chart is awesome. Two thumbs up for Brent Jesse tubes too. I bought my 6SU7WGT input tube and my vintage 6550s from him with zero issues. Thank you for the help.
-RayRod
5 Likes
That didn’t take long to resume the journey!
I ordered a 12AU7 9 pin to 6SL7 8 pin tube adapter from: Deyan | Headphone Reviews and Discussion - Head-Fi.org.
As for input tubes, it really depends on your sonic preferences per @PaisleyUnderground. I generally prefer to use tubes that are not warm with my Mogwai SE. I picked up a 1970s Tungsram Czechoslovakia made from Brent J that I’m quite happy with ($40) – Telefunken like sound signature.
5 Likes
Deyan makes great adapters. Way better than the stuff off eBay for sure. I picked up a bundle for my GOTL and I’m very happy with the purchase and look forward to getting more.
6 Likes
Nice. I’m quite happy with his work and responsiveness also.
4 Likes
@bpcarb
Thanks for the help. Should I just PM Deyan about the adapters or does he have a website or something?
You bet. Yes, PM him per @Earmuffs. He’ll be shipping from Bulgaria. I received mine in roughly 3 weeks.
2 Likes
+1 for Deyan’s adapters. He can make you pretty much anything and the cost is very reasonable for custom. Much better quality than the eBay/China adapters out there and he stands behind his work.
Here is the 12au7 → dual 6j5 adapter he made for my BHC:
8 Likes
Indeed. You’re making me BHC curious.
1 Like
