The following is meant to provide some feedback on the new Torii MK4 and on my (input) tube-rolling attempts.

I finally burned in my Torii MK4 for 100+ hours.
So, IMHO, the sonics have stabilised enough for me to report on my tube-rolling attempts.

My Audio Chain consists of

Oppo BDP 95
-> Soundsilver Symmetry Interconnects
-> Torii MK 4
-> Clearday Double Shotgun Speaker Cables
-> Alesis Monitor One Mk2 (Passive) Speakers (TEC 1994 Winner)

Tubes Used (Kept Constant during input tube-rolling)

Rectifier : Brimar 5R4GY "D' Getter
VR Tubes : RCA 0A3 "D" Getter,
                RCA 0C2 "0" Getter (any "D" getter versions out there???)
Output Tubes : GEC KT66 Gray Glass "D" Getter

Observations
1. The Torii MK4 is very transparent.
I also have a SE based EL34 tube amp (6 Moons Realisation award winner) which is also very clear sonically.
Both have the same resolution so Steve did not "BS" us when he made the bold claim that the PP Torii MK3 (and now 4) amp has the transparency of an SET based amp.

2. Because of the sonic transparency, in my system, the "best" sounding input tube would therefore be a "warm" one.
I rolled the following input tubes

(a) Philips (Holland) E88CC SQ Gray Shields "O" Getter
(b) Telefunken E88CC <> "O" Getter" Gray Shields
(c) Lorenz Stuttgart 3 Mica CCa "O" Getter Gray Shields
(d) Mullard (Holland) PCC88 Pinched Waist "D" Getter Gray Shields

No major surprises, the best sounding is the Pinched Waist, (d) above.

Tube (a) Had a nice touch of tube warmth but was not warm enough in my audio chain.

Tube (b) Had wonderful mids (and presence) but the bass was really lacking

Tube (c) Turned my Torii MK4 into the "Mystery amp"
High Resolution (HD Tracks) FLAC files sounded fantastic.
Low res Redbook CD FLAC were sonically atrocious.
If I lived on only High Resolution FLAC files, this would be my ticket.

Tube (d) Is the "Best" because it retained the sonic strengths of (a) to (c) whilst it overcame all the various shortcomings the above-mentioned tubes.

The Pinched Waist had
(i) More tube warmth than (a)
(ii) Had the glorious mids of (b) but was not lacking in the bass department
(iii) Was more forgiving than (c) above.
My low res sonic files did not sound like crap.
In fact, they sounded so good and non-fatiguing, I listened to low res files until 4 in the morning during one of my sessions.

Input Tube Recommendations (and musings)
My audio chain consists of pure silver interconnects and speaker cables so a warm input tube sounds best.
Any other CCa (e.g. Siemens) type of tube is likely to create an overdose of sonic transparency.

3. The Torii MK3 was built based on EL34 tubes.
On the new Torii Mk4, if you use a fat coke bottle rectifier (e.g. 5U4G or 5R4G) and 2 of those fat bottle output tubes (e.g. KT66), during installation, the tubes are likely to "say cheers" to one another!
After installation, the ventilation gap was only around 1-2 cm.
I hope this does not affect the tube life of my NOS tubes, I would have preferred a ventilation gap of at least 1 inch.

4. Sonic Depth and Width
The Torii MK4 has very good sonic depth and width.
The input tube also plays a part in affecting the size of the soundstage.

5. Positive Feedback Switch
My speakers did not whistle so it is compatible with this feature.
In my system, when the switch is turned on, it seemed to cause an expansion of the soundstage by at least 2 fold.
However, the sonics were more diffused and I preferred to leave the switch turned off (permanently).

6. Bass Switch
Bass was over boomy if I turned it on, so I left it in the "off" position (permanently).

7. Treble Switch
I left it (permanently) in the middle position cause it sounds wonderful to me.
Did not really experiment with this.

8. Volume Knob
With my current tubes, and my 88db speakers, I never have to turn the volume beyond the half-way mark.

9. Speaker Impedance (aka Epilogue)
This is a caveat to the above.
My Torii MK4 was built with 8 - 16 Ohms speaker taps.

However, despite the fact that
(a) there is a speaker impedance mismatch
(b) my speakers have cross-overs

The 8 Ohms tap sounds so good when paired with my current 4 Ohms speakers (with cross-overs!!!) that I'm seriously thinking of abandoning my original plan to use the amp with the 16 Ohms Zu Soul Superflys.

Hi Scott,

I've been using only the GEC KT66 in my Torii MK4 since the very beginning.

The reasons are due to the following below.

I learnt a very expensive lesson from tube-rolling various NOS EL34s ( on my non Decware SE EL34 amp) and 6DJ8 tubes (on my CSP2+).

For the EL34s, I started out with Mullard Xf2s ( and Other Mullard variants ) and then rolled Amperex "D" getters and finally the metal base philips EL34s.

Likewise for 6DJ8 tubes, I spent a minor fortune playing with almost all the various makes of tubes mentioned in Joe's tube lore and other exotic tubes such as Tungram, Teslas, Russian and Lorenz Stuttgart tubes.

My conclusion is that, most of the time, conventional wisdom applies when it comes to NOS tubes.
If I had just bought a pair of Pinched Waist 6922s or Metal Base EL34s in the very beginning, I would have saved myself a lot of $$$$ in the process.

So when Steve announced that KT66 tubes work better than EL34s, I decided to just get a Quad ( I got 2) of GEC Gray Glass NOS tubes and be done with the tube rolling.

For the rectifier, I also decided to tap on the experience of another tube roller.
He concluded that the Brimar 5R4 rectifier ranks alongside the famous GEC U52 rectifier.
I carried out a simple 5R4 rectifier shootout myself and found the Philips 5R4GYS to be a very good rectifier too BTW.

So some lessons I learnt from tube-rolling are:

1. Always get the "best" NOS tubes at the start
Coz it will work out to be much cheaper in the long run

2. Input tube sensitivity
The Torii MK4 is very sensitive to tube rolling.
By keeping other tubes constant, a Torii MK4 owner should be able to get the required sound he likes or requires just by changing the input tube.

I think this applies to just about any other Decware amp (e.g. CSP3) due to the inherent simple design.
The stock tube configuration should be good enough for most audiophiles but Decware amps will scale upwards sonically if one uses better NOS tubes.

3. Tuberolling can still spring surprises too
This seems to be a contradiction but I've found the Siemens E288CC to work exceptionally well in my CSP2+ and CSP3.
This is despite the bashing from Joe's tube lore.
So despite my current disposition on tube-rolling ( or lack of), I would still encourage anyone to tube-roll, but only if their budget allows for it.

I also sincerely hope that other fellow Decware fans will share their tube rolling experiences.

Lord Soth,  I did a little research this morning and can't find the Mullard PCC88s.  Where do you get these?  I have good results buying from Tube Depot or Upscale Audio and they don't show these.

Scott

If one was on a budget, couldn't upgrade all their tubes at once, or is just a cheap bastard like me, would you recommend putting your money more into NOS input tubes or better output tubes?  Where's the best bang for the buck, or are gains worth the money regardless of where spent?

The Philips 5R4GYS Rectifier for about $50 ea from Upscale Audio is highly recommended as one of those best bang for buck upgrades.

Steve mentioned that the gain of the input tubes for the MK4 was increased over the MK3. So any investment in the input tubes will be worth it,I.e. The MK4 is very responsive to input tube rolling.

Never tried the 5R4 type in the Torii. . . saw a pair of RCA on ebay cheap and went for them. Thanks for the nudge.

I really like the old RCA 5U4 in the Torii now, so they have a lot to overcome. I've never preferred anything but the 5Y3 type in the CSP2 or CSP2+ or ZP3--the larger rectifiers just alter the sound from "neutral" too much for my taste and material.

I have never tried the 5R4 type in the Torii either, but forum member Will has kindly lent me a pair, that I will soon audition. Looking forward to seeing what they do.

I'm with Lon on using 5Y3 types in the ZP3.  It's what Steve voiced the ZP3 with.  I've tried several 5U4 variants in the ZP3, and thought they distorted the sound.  It sounded off.

I like pre WWII RCA 5Y3's in my ZP3, but have found a 40's KenRad 5Y3GT (hanging filaments) that has adds a bit of slam/kick to the sound.

Mike

Got these in. Tried them a few hours. Took them out.

Not for me. Too dry and tight and big sounding, not accurate in my system. Reminded me of the Valve Art 274B. When I can let them burn in for a day or so I will and try listening again.

My findings for the RCA in the Mk III are similar to yours. They may never go back in. . . .

I'll stick to the wonderful old RCA 5U4G that are in now.

Just wanted to share more details about my Torii MK4.

It currently sounds better without the CSP3 in my audio chain.
https://www.decware.com/cgi-bin/yabb22/YaBB.pl?num=1386397153/0#0

At 150hrs, it has really bloomed like a sonic rose.
This will really be the last amp I will ever need.

You have been running your amp 15 hours a day?

I was going to start a new thread but decided to ask my question here.  A few days ago i took out the KT66's and put in some  Siemens/RTF EL34's.  I was surprised at the difference...I prefer the EL34's...at least for now.  My question is, has anyone tried the 6L6 type tube in a Torii.  I'd also be interested in what input/signal tubes people are using in the Torii and CSP3 and their impressions.  I'm using some Amprex 7803's in the Torii which I like.  Mark.

I must agree tube rolling is expensive, I have settled on RCA 5U4GB rectifier Top O Getters, Sylvania OA3, matched quad RCA 6L6GC Black Plate, Mullard gold pin E88CC 6922. I was originally a bit disappointed, but now a few months later the sound is really coming along nicely, especially using my Klipsch RF7ii, at first they were way to treble sounding, I have put a 10 ohm resister between the cross overs to get a bit more bass. I purchsed the speakers same time I got the amp, so both bits of gear sound a lot warmer now, I only play records on this system. It is pretty hard when the speakers have 101db senstivity, I have to buy new or mint condition records, anything less is a waste of time.

Thanks for the update will. Glad you are enjoying the amp so much!

LS,

I imagine you will be impressed with the EL34s, especially since you are a tube guy and can mix and match to refine. What I think I heard was all that is reflected in the MKIV refinements over the MKIII, as well as the long heritage of the MKIV development having been part of an EL34 lineage, the EL34 MKIII being its starting point. I don't recall how it went exactly, but suspect Steve did development of the IV with EL34s, and later, in refining the design and voicing, got to preferring
the KT66 for their many good qualities.

It of course depends on the other tubes, and the stock Ruby 5U4G, OC2, OC3s, and EH 6922s are all sort of big and/or open.

All in all, I suspect there will be a number of folks who prefer EL34s and a number who prefer the 6L6GC/KT66 family, and probably ones like me that like both.

Will

It has been a couple of months since I listened to my Torii MK4.

I have lost track of the exact number of hours in total but I believe that my amp and current tube/speaker combination has reached a new final level of musical enjoyment.

The forgiving nature of the Torii MK4 now applies to every piece of music which I play on the system. I suppose this was the trait of the Torii MK3?
By "forgiving", I'm referring to the aspect whereby one can listen to every single track of any CD and not be put off by any song.
Most amps and audio systems are such that one can only listen to a couple of "favourites" and have to skip the other tracks.
This situation no longer applies to my Torii MK4.

In addition, I'm finally at the ZEN stage whereby I no longer analyze any of the music tracks.
Every music track I play just grabs me and makes me float in the music.

I also mentioned earlier that I was using mismatched 4 ohms speakers on the 8 ohms taps.
Now I really won't consider getting the 16ohm ZUs as originally planned coz I really don't need it any more.

I sincerely hope all other Torii MK4 owners out there will also reach this audio level with their audio chains too!

Just a quick summary of my audio chain:
(No more need to tinker anymore!!!!
Oppo 95 -> SoundSilver symmetry silver cables -> Torii MK4 -> Clearday DoubleShotgun silver speaker cables-> Alesis Monitor One MK2 Passive speakers

Tubes: ALL NOS
(Also finally no more tuberolling required!!! Whew and a tremendous sigh of relief)

Brimar 5r4GY rectifier "D" getters
RCA NOS OA3 "D" getters
RCA OC2 "O" getters
Holland Heerlen made Pinched Waist PCC88 "D" getters
GEC Gray glass KT66 ("CUP" getters??? my guess since the gray glass obscures my view)

Hi Will,

Thanks.

My current Torri MK4 combo now allows me to enjoy redbook CDs, and even MP3s too!
I have some music tracks bought a long time ago from Amazon and they were only available in that format.
The MP3s no longer sound like CRAP.

Hi res files still sound better but I am no longer restricted to just hi res music as when the Torii MK4 first arrived in my home.

My Tony Bennett Duets redbook CD currently sounds like a "live" jazz performance is taking place in my home.
I won't even need to get a hi res version if such a thing exists.

I couldn't be more pleased with the results you're all getting with the MK IV post burn-in and just wanted to drop in to say hi and give you some insights...

My favorite input tube in the TORII MKIV is a Siemens PCC88 / 7DJ8 long bottle.  However, 7DJ8's in general are great due to their high linearity in this amp.  Really tightens the bass on problematic speakers not to mention the transparency and silkiness are amazing.  

My second favorite is the 6N23P and I am trying to ship TORII's with this tube in place of the Electro Harmonix 6922 due to recent noise issues with the current batch of EH6922's.  

The 6N23P tubes are all over the place matching wise.  I bring this up because I found in the TORII MK IV as well as the Mystery Amp, it is important to have both input tubes matched in gain so that both channels put out the same amount of power at any given point on the volume dial.  With dual volume it of course wouldn't matter, but with a single ganged volume control it's nice to at least start with perfectly matching channels.

So using the 6N23P I installed 10 tubes in the MK IV, one at a time and measured the power output from the amplifier to see how big the differences would be.  (iPod as a source with 1/2 volt output) and the amplifier turned exactly half way up, which represents a nice healthy listening level on most any speaker.

The lowest tubes allowed the amp to put out 2 watts RMS, while the highest tubes allowed the amp to put out 13 watt RMS at the same volume setting.  Also the weaker tubes that gave the 2 watt figure limited the max power of the amp to 20 watts, while the stronger tubes held perfectly clean past 30 watts.  

Bottom line is that you don't really want to have 3.4 watts on one side and 6.5 watts on the other because your imaging will suffer as well as dynamics.

And as far as I can tell when studying the amplifier at listening levels there is a PEAK RMS level of 2 watts with the average being less than 1 watt.  However, the peak power at this same listening level is over 17 watts making it's headroom exceed 12db on the weakest input tubes.  Of course if the music wasn't compressed and we had normal strength tubes this same level would yield almost twice that.  Ahh, the magic of tubes... 24dB of headroom is more than most CD's with compression of any kind so the dynamic headroom of the amplifier exceeds the ability of the recordings.

Anyway, if you run your TORII MK IV's with EL34's and haven't tried 7DJ8's be sure to do so.  Same is true for most other output tube choices as well.

I have been listening to Siemens tall bottle PCC88/7DJ8s for a few days now. Not enough for them to be burnt in, but they are really sounding good here too with cryo'd Tungsol KT66s....rich, balanced, warmish, and detailed.

Hi everyone,

I'm a big fan of the Game of Thrones ( "GOT" ) mini-series ( music + show ) .

Wanted to share some more of the great experience I am having using the Torii MK4 in a home-theatre setup.

I am getting amazing 3D holographic sonics with just a simple 2 speaker system without any subs or room treatment .... Blah blah blah.

For e.g., during the opening sequence of the GOT, there is an orb representing the Sun. There is a sonic effect of "sizzling" heat emanating from the Sun from different vantage points from a 3D sonic viewpoint.

The sound of the sizzling heat was so intense and realistic that a family member sitting on the sofa with me jumped slightly coz she thought that she would be burnt to a crisp by the Sizzling Sun!
There is no real heat generated, of course, except from the tubes but this just shows how realistic the Mk4 can render 3D surround sound for home theatre usage!

Hi LR,

I've seen the online pictures of your wonderful setup.
Your listening space is more demanding than mine.

My music / home theatre room is a cozy man-cave whereby my position is slightly further than near field listening - about 12-13 feet away from the speakers.
This is why, IMHO, I could  still get those 3D effects without having to fiddle with room treatments and such , which I believe is required for most listening rooms.

My setup is based on just the simple principle of the audio equilateral triangle.
I also went through a diverse bunch of interconnects etc like most people until I reached audio nirvana.
System synergy was also by luck, I suppose.

6V6 will not work in this amp.

I have not tried 6L6 in the amp. The 6L6 is an older development that the KT66 was meant to improve on. According to Steve's tube comparison chart, a 6L6 offers an overall wetter tone (more lush?), less power, looser bass and muffled highs. Why anyone would want that over the KT66 or EL34 is beyond me.

Just ordered a quad of TAD 6L6 from cryoset. Using the KT66 has made me want to experiment. With the bass control on the Mk III I can fix any loose bass. My recent very positive experience with cryo'd TAD EL84 in my Zen C amp has me wanting to try more TAD tubes.

I have about six hours on a matched quad of cryo'd TAD 6L6WGC-STR in my newest Mk III and I am enjoying the sound. Sort of a cross between the cry'od 6CA7 and the cryo'd Tungsol KT-66 that I have been using recently. Quite dynmic and rich sounding, not quite as big and open as the KT-66 but more so than the 6CA7 and a darker, richer sound. Very promising, let's see how they burn in. I've been quite impressed with TAD tubes, they are very well made and the EL84s I bought for the C amp in my Dad's system sound superb.