The MK5 uses 3 amp fuses (3.15) not 6 amp.

Welcome Fabio.

I'm a big fan of the Swiss Digital Fuse Boxes--one of the best improvements I've made to the system in the past years--I have three in use with Graphene Sluggos. Though "audiophile fuses" made a difference, these Boxes are a step even further. As I am sure you have discovered they really do assist with resolution and dynamic contrast.

I would strongly recommend using the values of fuse/Swiss Digital Fuse Box that Steve posts for the component and not varying them either higher or lower. So get a Box set up for 3 amp for the Mk III and when the time comes one set for 5 amp for the Mk V.

I had Mk IIIs (three of them at once for a spell--two in my house, one at my Dad's) and before that one of the first Mk II ever made and fuses blew a few times. . . and not at start up. . .rectifier related failures. I think it's best to follow the recommended values. And yes, I don't use the Pigtails either--never tried them, I had on hand and use the same great power cable before and after the Fuse Box--that works well.

Interesting. On another forum two posters said using that adaptor was detrimental to the sound. Good to know it isn't.

Yes, I read that too. I didn’t notice any significant negative effects after sufficient burn-in. For example, if a power cable is terminated with gold-plated plugs and the adapter isn't, there may be a slight difference.

If you have identical cables on each fuse box, that’s the ideal setup. However, if the need for two cables has been holding you back from purchasing additional fuse boxes, give the adapters a try — they’re very inexpensive.

Hi Will,

Thanks so much for the insightful reply. The forum has already proven to be a great source of inspiration and incredibly helpful. Especially when it comes to new gear, it always helps to consult others with more experience. So thanks to all of you!

The missing bass knob doesn’t bother me at all. I have so many ways to adjust the sound by changing signal or power cables, or rolling tubes. Having the treble knob alone is phenomenal. I was very pleasantly surprised by how strong its effect was.

The gain knob would definitely be helpful for gain riding. I can currently adjust gain on my DAC (via the high/low switch) and, of course, on the IcOn autoformer. The MK5 will eventually give me another option.

Interesting how you simplified the “fuse setup.” I think I’ll play it safe and just order two: one each for the MK3 and MK5. Also interesting were your findings about the graphene Sluggos. On the switch, I ended up removing an SDFB and going back to a SR Purple, which is warmer and more musical. Swapping the Sluggo would’ve been another option. I had a similar experience when switching from SR Purples to SR Masters. After the third or fourth Master, the overall presentation became too forced and clinical.

I’ve had fuses blow on me in the past too, and since I’m not able to repair anything myself, I prefer to play it safe.

Speaking of rectifiers. I read on the website that the MK5 uses an 8uF capacitor, which makes it more rectifier-friendly for tube rolling. I assume the MK3 doesn't have that feature. I was wondering whether I could use my Type 80 rectifiers in the MK3. I saw a post where someone used them in some Decware amps (though I’m not sure if that included the Torii MK3). Given the lower output current rating of the Type 80 compared to the 5U4G, I’m worried I might overload or burn them out quickly.

Very good point. I‘ll ask Mark to include a copper and gold sluggo too. Another easy option to tune the system. As you say, he‘s a very nice guy to deal with. Also very open to critical feedback. From what I know he started developing a proprietary adapter to avoid the pigtails which really don’t do his product any justice after having received several feedbacks.

We ended up with the treble knob ~90% open too. With Siemens 6922 we were around 75%. With Tesla Gold Grid which is slightly richer we increased to ~90%. I’m with you in terms of treble quality vs. attenuation. In the end it’s also a question of balance, personal preferences and quality of recordings.

Thanks on the guidance on Type 80. I have globes and coke bottles. I prefer some of them over 5u4, 5y3 and 5ar4 in my DAC. Most measuring strong or being NOS/NIB. But I‘ll probably abstain from  experiments. Even if these are less pushed in MK3, I don’t want to blow these for nothing. There’s plenty of options still.

The globes are usually airier. Especially the very early production RCAs. Some of the STs are meatier with higher tonal density. Also here, all a matter of taste and starting point I guess.

I really look forward to receiving my Torii. Such a wonderful sounding amplifier and such a joy to tune.

Started to look into the ZROCK3. Don’t think I fully understand yet. Will lool for more information today.

I have used several different 5R4GYs without issues. Steve's amps are generally pretty flexible with being able to work well with some variety of tubes in any of the positions. Some exceptions, but generally pretty nice latitude. Sounds like things are getting really good there!

Though I have no GZ37s, having used GZ30, GZ32, GZ33 and GZ34s, your observations make some sense to me. After using mostly 5U4G types for quite a while, I found the speed and dynamics of the GZ family exciting...reminding me, though much less variable, 5R4GYs being one type electronically, I found they can be similar in speeds and opening the soundscape. My setup warmish as a baseline, GZ30s went too far here toward lower power, leaving the sound too lean in general. And 33s and 34s tended too far into signal intensity here, with a bit too much density/concentration, darkness and fullness in my setting.

The ways I hear it, this is a lot to do with how powerfully or not the given rectifier pushes the other tubes. All else the same, if every aspect of the signal is stronger, I find that will increase every aspect of the sound, creating more signal density, fullness and extension. But music reproduction, wave length influences, and rooms being more easy to obviously mess up the bass and how it balances... too much signal power and concentration makes the mids and highs harder, but less obviously "off," but it can make the bass cancel and amp up parts of itself, while making it slower and more smeared... sometimes to a point of feeling like less bass while being too much bass signal for the system/room to "digest" ....slow and thick rather than defined, dynamic, resolved, textured...

All rooms and systems having countless influences on resolution, speeds and space, hard to guess exactly what will be "best" with given tubes, but I am with you, we can compare the characteristics of tubes and try to fit them in by comparison. And all else the same, at some point more tube power, if it goes too far is an important indicator for tuning, the signal so strong and concentrated it can overwhelm the system and room, while throwing off the potential for the amp's complexity of resolution, speeds and spectral balances.

Clearly countless variables within all setups create variable beginnings. But with the Torii's many tubes and adjustments, as you are experiencing, their relatively transparent and resolving nature shows tubes well, and they can allow a lot of ways to experience the beauty of different tubes and tube synergy... each of the five tube positions powerful sound shapers, and mixing and matching tubes that might be too much in some sets, or not enough in others, can result in musical beauty.

But as I have said, I personally prefer to go for relatively resolving, complex, neutral, and fast balances with all the tube choices, less tube extremes and compensations making playing well across recordings easier for me. And each contributing their own influences, with five tube positions in the Torii, and for me, 6 other tube positions before the Torii, even within relatively narrow sonic perimeters, there are lots of ways to experience the music, awakening my perception and experience in different ways, and in doing so, changing me and my life.

So in this particular setting, the power push from the GZ32s was my favorite of the GZ tube types. The whole faster and less smeared than their more powerful siblings, allowed more unaffected complex resolution and immediacy... more space contributing to more defined edges that remained complex...the whole more live feeling. With all levels of resolution and dynamics rising out of more open space across the spectrum, they tended to be mildly warmish, but not overly full or concentrated, the bass fast and complex with just enough warmth to sweeten mids without slowing or darkening. My system and room does tend to be warmish without compensations though, and I especially liked especially transparent and resolving Mazdas with double rectangle bottom getters. And on the other end sonically, some late 50s Mullard GZ32s were quite nice with the right company, but all in all needed compensation in this setup, tending a little too dark, full and slow for me overall. And no doubt, some rooms might arrive at similar balances I get using stronger tubes like GZ33s, or 34s, or 37s.

5R4GYs to me can be nice similarly to the GZ32s, tending toward fast and spacious, while pushing the other tubes (and therefore the signal) less forcefully than some rectifiers. When they work, they can give similarly nice balances with good speed and space throughout, allowing complex fine detail, immediacy and dynamics everywhere. But then, like all the tubes, depending on the setting, some of them could be too open and spacious, some fuller/warmer and less extended, etc.

Of the 5R4GYs I have used, some black base Fivres were the most open and fast... very much about space and clarity (with them you may need to turn the treble down again there), and some NOS Phillips, here, were just too slow, veiled and full for me to enjoy their good qualities. 50s RCAs are always nice at first, but finally a little veiled for me, lacking some top extension, and subtly a little slow. 5R4GWYs can be nice depending what is needed too, with their different shape and added damping, tending pretty open, but also pleasantly smooth and mildly warmish. For me, very fine resolution and speeds, along with subtle musical warmth, a necessity, the GWYs tend toward being a little too smooth and lacking in fine detail complexity, but I recall them as being nice really tubes if their characteristic qualities fit with all else.

To remind myself, not having used 5R4Gs in years, now I put in some brown based Sylvanias labelled 5R4GA, with hanging filaments, ribbed black plates, and a centered side horseshoe getter. I think some of these are called 5R4G-Bs with their semi-fat straight bottles, and compared to my more usual rectifiers, RGN-1064 globes and similar variants of B4, 4V euro tubes I have been tuning with for years, the Sylvanias are a little too full, and a little slow and lacking in dynamic contrasts for me. But this is me and my setup, and the Sylvanias, without notable imbalances with the other tubes I have in, I think they could be beautiful with the right company.... just not as natural, alive, and musical with the rest of the tubes as they are.

Importantly, for reference though, my setup is heavily modified across all components, and tuned for very complex speeds and resolution without concentrations or hardness, making it really easy flow. This makes any tube stronger than in most Decware gear.... so most "normal" tubes that fit well for most people, similarly to solid "sluggos" here, tend to be a little strong for me, especially without compensations.

Anyway, relative to signal power, I use OB3s, for my setup, pleasantly a little milder than OA3s, and OC3s sometimes a lot of fun for their open spaciousness, but they eventually end up being a little clean for me. I used them more often before modifying my components for less smearing and more enhanced resolution and speeds, and I am guessing that if you try your GZ37s with your coming OC3s, OC3s pushing the other tubes less powerfully, the GZ37s may end up somewhere a little closer to the Marconi 5R4GYs with the OA3s you now have. As things were before the Marconis, a strongish GZ rectifier, and the OA3 the strongest VR for signal power, the OC3s will relax half of that, changing the whole a fair bit. Not that this would be "better or worse," but I bet it will be fun to explore!