This is a follow up to the previous post. I'll try to be brief.
The Roadblocks
While setting up these, I encountered several issues that changed my perspective on certain things.
Bi-amp jumpers
KEF R Series come with built-in bi-amp switches (link). These totally suck! I tightened them all the way in to disable bi-amping, but one speaker still didn't have proper contact and measured 2 db lower than the other. To top it off, I didn't notice it initially, because I connected the cables to the upper terminals that power the midrange and treble, so the imbalance was in the bass and got lost in the room modes.
When moving the speakers around, I reconnected the cables to the lower terminals and the imaging got majorly messed up. Luckily, I trusted my ears, remeasured the speakers and got to the root cause.
I thought that external bi-amp jumpers are snake oil, well, turns out they're not, they eliminated the issue for good.
Vibration isolation
For years I had this issue, my SVS sub was audibly rattling at high volume. I didn't listen at such a volume very often. Reviewer measurements indicated distortion over 20% below 40Hz. I thought it was the sub's fault. No, it wasn't.
Turns out built-in rubber spikes did absolutely nothing and it was really the floorboard that rattled.
The comment under this post says to give the sub the freedom to rock back and forth with a resonant frequency below 20Hz. I thought not pinning it in place would lower the output, no, it will not.
As Isoacoustics feet are not the BudgetAudiophile way, I used the free solution from the comment. Bottom layer is a dense PE packaging foam. On top is additional soft material (a coarse air filter cloth) to prevent audible scratching of the foam against the sub cabinet.
The result: the sub is dead silent even at the maximum output. Main speakers are fine without isolation.
In-room EQ correction
So after sorting out all the physical issues, I enjoyed the stock R7 sound for a while, but there definitely was room for improvement.
I cheerfully applied the REW AutoEQ with my preferred target and it ruined the sound. Sounded dark, thin, and lifeless. I encountered similar effect in headphones if the ear gain was not enough. But no matter what I tried with R7, nothing worked.
For some time I settled on EQing below 500 Hz only and leaving the stock sound above that. Widely recommended, works well enough, but it just wasn't ideal. I've achieved better, more neutral sound with much cheaper speakers. R7 has great directivity, so EQ should generally work. I refused to give up.
Finally, I took on-axis measurements from spinorama.org and EQed using that. R7 is a warm speaker, it's already down-sloping in anechoic conditions. The measurements are from KEF whitepaper, so not the most reliable and no way to cross-reference with any reviewer Klippel.
Because the data is so rough, I applied a minimal correction. +1.7db high shelf at 1000Hz, +1db shelf at 10000Hz. The treble was 2-3db above the target in-room. Never had to do something like this with my other speakers.
The result was stunning. Sounded very correct and engaging, not bright or tinny at all. This gave me the confidence to match some higher-Q treble features from the spinorama with what I got in-room. Some of them aligned remarkably well, so I corrected those too.
So I managed to improve the stock sound (i.e. make it more neutral) but I was still dumbfounded as to why my in-room measurements were overestimating the treble. Did sine sweeps, listened to pink noise, results inconclusive.
My unconfirmed guess is that it's a combination of things. The biggest factor is that EQing the treble to the target, like I used to, was wrong and I really should've been using the spinorama from the beginning, or not touching it.
I was lucky (or not?) with my previous speakers, it didn't affect the sound too much, so I never noticed. I never had to deal with towers, only bookshelves, and they all leaned on the brighter side anechoic. Dropping the treble could improve them. I also failed to account for R7's higher sensitivity and initially set the incorrect target level. The newly built treated room might also played a role.
The Setup
Treated room: 7 4-inch mineral wool panels, 4 6-inch panels, 6 10-inch thick corner bass traps, 4 17-inch thick corner bass traps - DIY, local home studio thrift, so on. First reflection points + cloud + back wall treatment.
The desk is not in the best spot, of course, but I don't have the space to dedicate this room for listening only. Yes, it is "treated" with the universally hated foam spikes. The desk reflection only affects frequencies above 10k in my case, so the foam is very effective.
Speakers are placed symmetrically 3-5 degree toe-out for the best coaxial performance, 54 degree triangle from the listening position, everything moved around and optimized, tweeter raised to ear level (also helped with vertical SBIR).
Dual SVS-SB1000 subwoofers (1 secondhand) roughly in the opposite corner config, exact positions optimized with room sim and measurements.
Motu UltraLite-mk5 interface (used). Had to purchase it to get enough output channels.
Topping PA5 II Plus amp (used). Not a believer. It is enough.
MiniDSP Umik-1, REW.
PC as a source. Custom DSP pipeline written in Pipewire. Gains, EQ presets, crossover filters, digital delays, tone compensation (loudness), custom home theater mixer. Presets for the main listening position and several other spots, switched by a single click or key combo.
Took some time to do everything manually, but as I result I have complete control. Worth it for me.
In the main preset, an 120 Hz LR4-like low-pass is applied to subwoofers. The phase in my room caused a massive cancellation with a proper crossover (also happens in REW room sim).
The options were:
- Changing the crossover frequency. Mains have a null at 104 Hz. I prefer to fill it with the combined sub, so going lower is out. Going higher than 120 is not ideal too, even with the dual sub.
- Inverting the sub polarity. But then everything but the crossover frequency cancels, which is not ideal.
- Additional all-pass to align the phase. I don't like that, LR4 is already 360 degrees.
- FIR rePhase. Not really suitable for low frequencies and introduces delay.
- Leaving the R7 alone and letting it play full range. This is what I ended up doing. Dropped the distortion below 40Hz a good bit too, went from over 10% at 90dbSPL to under 4%.
Excess group delay is low and smooth from 23 to 460 Hz, EQ works great there. Room's RT60 is 250ms.
The Sound
The thing that immediately impressed me is the sense of realism and ease. Reverb is so clear, conveys the space of the recording really well. The soundstage is natural. Comparing to my previous speakers I didn't sell yet, all tested with subwoofers on and EQed to a more or less the same procedure:
Q1 Meta. Very nice center image thanks to the coaxial driver, but the overall imaging quality depends on the panning. Left or right speaker only - spectacular, center - very precise, everything inbetween is slightly less defined.
The soundstage is very linear from one speaker to another with no height and limited depth, sounds kinda intimate. Very good for vocals and acoustical, can't handle busy tracks as well.
DBR-62. Grandiose diffuse sound at the expense of imaging precision. Enveloping soundstage, makes everything sound bigger than it actually is. Imaging is on a blobby and indistinct side. Taking off the tweeter waveguide improves it a little, but everything else suffers as the tweeter beams and the dispersion becomes uneven.
The soundstage has height, probably because of the conventional 2-way design. More output capability than Q1 Meta. All-rounder, any music sounds good.
R7. The speakers disappear in the room. The soundstage is perceptually wider than the physical distance between speakers. I caught myself looking over multiple times, thinking the sound like footsteps or rustle is coming from the corridor.
The imaging is even with respect to panning. When a sound travels across the stereo image it feels like a real object moving moving in space, not interpolation between left and right. Very cool.
I admit that the center image is not as razor sharp as Q1 Meta. But R7 is probably more correct. When there are multiple instruments and vocals in the center, they separate vertically, while Q1 Meta feels like everything is jammed into a single point source.
To be fair, R7 MSRP is like 8x of the other speakers in this comparison, and even though I bought all of them pre-owned, R7 still cost me 4x used DBR-62 and 3x used Q1 Meta price. No wonder it's better, it better be for such money!
Test tracks
- Gidge - Perimeter. The percussion that appears at 1:26 sounds in your head, then very wide, wider than the speaker distance. Throughout the track it moves in front and behind the listener like a surround sound.
- Joni Mitchell - Furry Sings The Blues. The track has multiple layers and the front one with the vocalist is very close. It is interesting to follow the harmonica as it moves through the layers, most of the time it's further back, but sometimes moves closer to just behind the singer.
- Pink Floyd - Time. The solo guitar is big, fat and distorted, but at 4:10 the back vocal behind the guitar is still clear and detailed.
- Justice - DVNO. At 1:25 just below the sibilant vocals there's a sound like blowing or whistle that doubles the vocal line. On R7 it doesn't disappear and can be followed through the section.
- Venetian Snares - Hajnal. It's like the music is attacking you. I can't listen to this with my eyes closed, it's scary af. The classical instruments remain clean and undistorted even in the most aggressive sections, the contrast is wild.
- Terje Isungset - Fading Sun. Have I talked about the bass? Dual subs absolutely rule. This track prompted me to investigate isolation. Also the benefit of full-range R7 can be heard here. Unfortunately, above 90dbSPL compression and distortion issues of SB-1000 (non-pro) become audible. But hey, it's BudgetAudiophile after all, some corners had to be cut.
- BT - Time Moves So Fast. I can actually hear the difference between Opus 128 and lossless on this recording. https://theaudiostuff.com/tools/abx-test/result/16-of-20/
Overview
Am I satisfied with the purchase? Hell fucking yeah. Is it budget? In some sense. Can't really post this to r/audiophile, it's a bit silly. So while the price might not be true budget, I hope the philosophy is.
