Torii MKIV Review Part Two:
Power tubes continued...
In addition to the above, I spent some time with Mullard reissue and Siemens/RFT EL34s, and 80s Russian 6P3S-E. Along with the Psvane 5881, compared to KT66s, all of these have softer bass, tend to a warmer richness to various degrees (even slightly syrupy depending on the rest) and with varying levels of notable clarity uppermids up. In this context, the brighter/cleaner upper mids can feel like emphasis, especially with the EL34s, and then especially the RFTs with their pronounced detail complexity emerging from a rich warmth. This is always seductive for me at first, but a bit of a challenge after the relative neutrality of the KT66s, their tighter bass, openness, and “revealing-enough” upper mids.
Preferences.....But in the end, though it takes some effort to really get the most from any power tube, it is there to be had with all I have tried.
That different power tubes can transform the MKIV signature from within its unified and refined foundation....and quite musically and tastefully, I think this is pretty impressive! Great for a tube lover, this is a testament to how balanced, “real,” and friendly the amp's electronic signature is.
For my personal tastes and system/room, I think I tend to agree with Steve early conclusions that the KT66 is a very good choice in this Amp. And though I would not like to do it, if I had to give the rest up, I would probably be good with the Genalex. That said, they all can be really good with careful tuning and when they are in there, I like them best.
This leads to a revelation about this amp for me. If the source, room and system parts are up to the MKIVs revealing, complex, and sophisticated circuit (not hobbling it), I am afraid to say it, but I think this amp can actually make many tubes better! What can I say? If I am not delusional, I would call this a powerful indicator of how far Steve took this voicing.
The MKIV pulls the beauty of various tubes with great finesse.Inputs: In the MkIII, though 6922 types can be nice, their more solid, extended and articulate nature made them more difficult to tune to my tastes than 6DJ8 or 7DJ8's. I typically fell back on PCC88/7DJ8 for more micro detail, texture and spaciousness. But with the right tube compliments, I would occasionally really enjoy E188CCs/7308s. In general, they bring a nice touch of friendliness and musicality to the 6922 world.
And in the MKIV, it is easier for me to use these tubes, indicating further the care of the MKIV design and how friendly it is with tubes. 6922's, especially E188CCs/7308s can be a real pleasure....the amp circuit bringing out even more of their complex, atmospheric and friendly qualities...along with the expected articulation, extension and accuracy. I still tend to the generally more open texture of good 6DJ8s, and 7DJ8/PCC88s, but not as much as with the MKIII. I think I can say that the MKIV makes inputs bigger, fuller, more solid, yet still spacious, with excellent detail complexity. Though with recognizable traits, in some ways, inputs seem like different tubes in it...better. I loved the MKIII, but something about the MKIV way of using tubes pulls more amazement from me...it becomes less about how good the tube sounds and more how it becomes music.
And More TubesBut it is not all inputs and power tubes by any means. As with the MKIII, every tube counts in its impact on the whole. My main tube set over many months had been Genalex KT66, 50's RCA 5U4G-ST with top/side D getters, 40s Dumont labelled OB3s, Mullard labeled OC2s, and early 60's Amperex Miniwatt PCC88s, occasionally playing with other PCC88s or 6922/7308 types. But based on forum posts, several months ago I replaced the Mullard OC2s with British 7C51s and started exploring more 5V4/GZ32.
Quite similar to the Mullard OC2s, the 7C51s offer perhaps a little more fine detail, and the Mullards have been harder to find. Both are a step or two up in warmth and complexity from the articulate, but a little tight and cool stock Russian OC2s. I would put RCA OC2s closest to the Russians, but more spacious...more complex and lively... then Raytheons do the open RCA thing with a little more warmth...the Mullards take the warmth a little further while remaining lively and fresh; and finally, the 7C51 have a similar friendly “warmth,” not dark or veiled, but textured with good detail.
I will talk some of this later, but the big VR's are great tuning tools also, for me, one of the most important! The OA3 provides the most push on the power tubes, most tonal density, bass and fullness. Then progressively the OB3, OC3, and OD3 make the sound more open and spacious as density and fullness decrease. And within this context, vintage and make of the different tube types can be easily heard if the system is revealing, with variations in warmth, spaciousness and detail. Altogether, very powerful tuning tools!
Rectifiers are powerful as well with loads of variations depending on types, vintage and make. I have mostly explored 5U4Gs, 5R4GYs, and 5V4/GZ32s in the MKIV. The 5R4GYs tend to be very solid and articulate. I like Chatham 5R4WGYs for open articulation with some mild warmth, but they are a tight fit if you use KT66. I may have cracked one of those big crazy bases this way, but you can sort of angle the KT's out I their sockets and the 5R4s in to separate them a bit more...still close though. RCA 40s and 50s 5R4GY are good choices if the tube set needs a high quality, extended and very clean and open rectifier sound.
Of the several 5V4G I have, I generally prefer the even balance and inner detail of my old “standard” Torii Rectifier,
RCA 5U4G-ST's. But the
5V4s...my RCA 5V4Gs and GE 5V4s tend to be a little lean up high, and a bit thick low down. But not the Mazda GZ32s! Sort of bridging a good GZ34/5AR4 in speed, dynamics and tight/open qualities, with the excellent frequency balance and inner complexity of a good RCA 5U4G-ST, the Mazdas give me really nice balance, solidity and enhanced tonal density that is fast, open and warm. Once I get close with a tube set, I often like to roll rectifiers, a great tool for final refinement. My system, but I think these particular GZ32s take the MKIV to a very good level.
Finally, with a moderate variety of quality tube choices, and with the MKIV's refined ability to use tubes well, you can go a lot of places with this amp. It is quite accommodating with convincingly musical signature shifts.Vibration: …is very well handled. The textured steel top plate? Internal parts arrangement? Placement for isocups (and all the other vibration mitigation I use) is still important, but subtler than with the MKIII. And that done, the need for tube dampers is subtler, though I do use them. The MKIV is a good step forward for reducing vibration noise, and big deal if we want all we can get from a system/room.
Amp Adjustments:I thought I might, but I don't miss the adjustments of the MkIII. With impedance and bass switches, treble knobs, and reconstructive feedback, tuning works really well with the MKIV.
Experimenting without EQ, all variations of adapting the amp to my system/room sounded quite good. Changes are clear but also retain the amp's natural voicing. Testing each parameter, though I have definite preferences, once I adapt for a minute, the sound is good. I think the adjustments do what they are meant to do with the integrity of the amp's refined signature.
Bass Switch: I have bass intensity challenges with my body and in my rooms, with the MKIII and IV. Because of this, I learned to love EQ for overall system/room fine-tuning with my MKIII. Once I got the MKIV, I just stayed in the habit. I prefer EQ in part for the richer mids with the bass switches off, selecting bass correction specific to room and tastes.
So until I started writing this, I hadn't used the Bass Tightening Switches much. But without EQ, they do musically reduce bass fullness, but with a still natural balance and impact. Here, depending on how bassy the tube set is, the low bass can still be a little too strong for my tastes and sensitivity to bass…but it is very effective while still sounding “right.” If I used the switches instead of EQ, then I might need to make some tube adjustments with some tube sets. That said, in the end I like having the edge to work with. I can carefully tune the bass to “just right” if it starts a little too much.
I like the sound of the switch in my room, and after experimenting with it some, was even tempted to explore using it with only very minor EQ. When EQ refinements of 1/3 dB, or changing the octave width from .08 to .12 can excite me, I think this is high praise for the sound of the switch.
Without EQ, the MKIII took more serious tube set refinement to get the bass "right" here. And the bass knobs have more effect on the tonal complex of the bass and mids. I like the sound of those knobs, but the MKIV and its bass switch offer better bass control while remaining true to the amp signature, making it better overall in my rooms.
Treble Knob: With EQ, I tend to use the treble knob pretty open. But when I roll tubes, I occasionally use the knob and find it a great tuning tool. By experimenting with an 8K high shelf in EQ, it is clear how useful this knob's range is. There is a sense of fine-tuning the whole of the sound...the mids, bass and the highs. Another excellent design choice by Steve.
Reconstructive Feedback: The circuit depends first on enough burnin...I think I recall 300-350 hours before it stopped sounding diffused. It brings out space, ambient information, and complex detail, so how it sounds also depends on everything from source on. With less of these qualities to begin with, the circuit is less noticeable. And even with a very revealing source it is somewhat subtle, but within that, really kind of huge also, as it effects the overall feel of the music.
Until that “right” place in burnin, I kept it off, preferring the more focused sound. But finally, its sound became tighter, more solid, and very tasteful in my system. Now it stays on.
Good soundstage here is generally similarly saturated both ways, wide and deep. But the sound with reconstructive feedback is different, increasing the sense of micro information and space in very important ways if you like a “live” feel. From note hits to fading trails, it feels like it takes bits of information and divides them into more bits, enlivening all things of natural detail and space. From the sound of wood, air, early and late ambient information..... the increased sense of resolution makes tones and edges more textured and smoother….more liquid and more complex at the same time. It somehow makes all the spacial aspects bigger and wider while retaining solid and saturated soundstage location for each player. It shows best in edges, in air, and in ambience close and far, but it is throughout. The space between and around instruments is richer in all spacial qualities. And really important for my room, the more “awake,” natural ambient information contributes to a convincing transformation from recorded music to “players.” Recording ambience seamlessly integrates with my room ambience.
I clearly really love it, but as with the other adjustments, the amp sounds excellent without.
Finally, though it generally did not change the already really good soundstage itself much here, I do recall as I was adjusting to the new amp, that it helped the soundstage saturation and locations at times. With mixes that had less skillful mixdown focus on soundstage, Reconstructive Feedback could bring out more soundstage definition.
There is a lot good about this design, but with my source and system/room, the Reconstructive Feedback switch is a big deal, in a sense, bringing the rest to fruition. The Mystery:I can say a lot about the MKIV and feel like it is accurate. But its most important traits, the ways it puts it all together, this is harder to describe. Its amazing musical detail, wide tonal balance, complex timbre, natural weight and body, its speed and unrestricted ambience…they are all special. And it is smooth without detail loss, and without being too smooth. It is relaxed and excited depending on the music. It is good at complex musical differentiation in dense recordings. I can hear all these "audiophile" indicators with clarity, but the mystery is in how seamlessly integrated these attributes are as they dissolve into the gift of music. As I listen and write, I am amazed once again at the way the amp integrates all its very articulate musical expressions into one seamless and adept whole.
When I first talked with Steve about the amp, he thought it might be a little less forgiving than the MkIII, and maybe the way my amps are set up is enough different from stock to change this. I don't know, but I consistently find the finesse in which the MKIV presents music more revealing AND more forgiving.
I have been exploring finding this particular balance for years, and my whole system and room is one thing toward the end of revealing with complete tonal balance and without hardness. The MKIV makes this easier and funner, increasing my musical pleasure.
Steve's 20-30% improvement with the MKIV? I am not good at these percentage things, as I feel like no matter how much the system improves over time, I am always working on the last few percent
. But for my tastes, the MKIV does most things in more complete and refined ways, and adding each of its many refinements progressively…I think I see how he got there. The Torii heritage is quite apparent, but this amp takes the lineage to new places.
That said, with the right tuning and setup, I can sit down with my MKIII and experience full engagement! Once you get that good, well….. it is just really good. But the refinements of the MKIV spread across every level of the expression of the amp, and therefore the listening experience. I find its balance of the voicing very flexible and refined.
I suspect there would be MKIII folks with great synergy who would like their amps better. Mid-burnin, I might have been on the fence, my MKIII tending to have an ingratiating, slightly wild character, but very beautiful, and the MKIV tending to being a little too refined, too predictable….. But as I got to know the MKIV, and it continued to reveal itself, I fell for its sophisticated and convincing ways of awakening music.
Final, Part Tree next
Pages: 1
Torii MKIV Review (Read 45466 times)
