The Rel subs have two parametric filters that I will try once Rel gets me the proper instructions. My guess is that the built in EQ may be enough. The X4 has a 60 day trial so wanted to test the DSP route also.
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My experience is, it needs a most suitable 3 or more band parametric EQ (possible in analog or DSP), variable phase adjustment and low pass crossover frequency (should be available in any sub) and flexible low pass filter/slope.
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Now you just need to spend time with an REL sub to understand why your rules may not be good rules for everyone. I prefer REL subs to simple rules.
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Velodyne is getting back into the market. My dealer is big on Velodyne, I might try them out some day. The best Velodyne Subs are DSP driven, with some models the DSP can be bypassed.
The one big issue I have with DSP subs, that make me hesitant:
- DSP Control is one way of making subwoofers work in the low frequency range where the drivers work in and beyond their resonance frequencies with a reasonable limitation of distortion. Small subs going to 20 Hz can only be realized by DSP
- DSP always comes with time delay, meaning they will never fit perfect in a system with analog amplification and crossovers, only if the mains speakers can be delayed by a smart algorithms and DSP, these subs can be time aligned for clean integration
My pre amp and integrated amp both offer Dirac with low frequency cross over features. This feature is known to not work with DSP driven subs. Two different DSP logics that seem to apply counter productive algorithms and cause undefined delays.
But small DSP driven subs are the only ones that fit our rooms, so I need to try them one day.
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Indeed I don’t doubt that especially REL subs are great.
I’d even agree that not using EQ is theoretically preferable to using it (one always has this choice even with an EQ’able sub).
But to not have that choice of EQ’ing, given there’s no room without strong peaks in the sub area (even with complete flexibility of sub placement), seems a bit like buying a tonearm without height adjustment. It may be good enough and feasible to play any cartridge with a fixed height, but it’s part of the basic idea and function to adjust an arm to the cartridge…just like imo the basic need to adjust a sub to room nodes (even if it might be good enough in certain situations - or even better - to use it flat).
I’d make a bet that if one has EQ available and certainly the option to run the sub flat, EQ would be used to 90%. It’s simply an option, that should be available imo, especially in deep bass. and especially because most are not even completely flexible in placement. One still has the option to use any EQ’able sub flat like for example a REL without this option, I just doubt anyone would finally do so.
Rega delivers the matching cartridges for their non adjustable arms. They have the SRA built in that doesn’t need further height adjustment, As far as I remember they have a center screw that even fixes it in a pre aligned position and they have a round stylus shape that makes them less sensible for non adjustable azimuth. So with their cartridges, their concept of rigidity first, works. But one can’t deliver a matching room with a sub.
But the nice thing is, one can even make the experiment with such a REL nowadays. Simply add a mini DSP configuration and see what’s preferred. My sub has multiple analog parametric EQ, which some prefer to going digital even in deep bass, but I’m not sure if this is really important compared to the general advantage of adjustability and the even higher flexibility of DSP. However, I’m not sure how the time delay for DSP is compensated. Possibly one has to place the subs ahead of the main speakers? Would have to read/Podcast listen into Darren’s config and experiments with his mini DSP setup.
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LOL
I bought a Tonearm without a height adjustment. It came with my REGA RP10. It’s a great Tonearm! When I ordered it without the assumed REGA cartridge I was well aware of the availability of shims. They come in various thicknesses so have a ball. It just amuses me that you caught me.
I have full range speakers in my main system, no subs needed. In my home theater setup I have two REL subs and my Anthem ARC works it’s magic to tune all my speakers with little effort.
My SUV uses rubber tires in case you were wondering.
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So if you conclude having a Rega arm qualifies to use a sub without EQ, you might be correct 
But as you use room correction with your EQ-less REL‘s, you’re not the best advocate for „no EQ“ anyway, you’re rather a concept-breaker
But then with shims you’re breaking Rega’s rigidity concept, too, even with a spacer at the arm basis for VTA adjustment you would, as they strongly propagate and follow their one-piece strategy and therefore decided to make most everything non-adjustable.
To stay in in concept-breaking you should think about using solid rubber tires on your SUV … you would have my blessing
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These rules can true for many setups. I wanted analog (even though I stream) integration with my sub and the speakers and I do find benefits with DSP. Since I use Roon, I can do DSP there in digital world before it hits the DAC. DAC to Pre and between pre and amp/sub I have the JL CR-1 which is a pure analog xover. Takes a bunch of boxes for what is really a 2 channel system but works wonderfully. So it can be done. I use the L/R as fronts and sub for HT as well. JL supports that mode too.
I actually was thinking of going with RELs using the speaker level wires and integrating that for 2 channel, but I was thinking I would need another sub for HT LFE unless I sent the LFE to the L/R channels which brings in own issues. Plus I dont have room for another big speaker box. So I went with Rythmik GHP25 and use for both.
Subwoofer integration is tough to get right, but when you do with 2 channel it makes a big improvement. EVEN IF YOU HAVE FULL RANGE SPEAKERS. I know many dont think its needed, but until you try it with a good sub, you dont know what you are missing.
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I think that experimentation is the key. No one solution fits all. Biggest take for my system/room is that the main speakers Must be in the right position for best room response for bass and upwards, then the subwoofer integration can be done following via either placement of sub at seating position and finding the best room/speaker integration or by measuring the response at various positions in your space. It can be done all in the analog domain if one wants to put the work in, but it takes days or weeks of tweaking/measuring/listening. Eventually one knows what works and what doesn’t. I have all those tools(miniDSP, REW, room simulation, and even employed Roon DSP). Subwoofer to main speaker integration/room and timing to me is the most important and secondly the room mode response. Finally the room acoustics should be addressed and that makes the largest difference.
My 0.0002 cents.
Cheers!
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I cannot and will not disagree with anything you said. You have a perfect understanding of all of this.
I’ll do my best to work on some cruder statements that are more attackable
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I had solid rubber tires on my tricycle. I sang soprano until my father stepped in and got me a Schwinn with balloon tires.
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I just got my DSD back from getting the transformer modifications done. It also has Jeff Richards power board installed. This DAC is absolutely fantastic with all the years of evolution. I have a Waversa VDac that I love too. Things have evolved over time and the Waversa has the edge on details and layers most music more effectively. However the DSD sounds almost analog to me in a good way.
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I’ve been the tire business for going on 30 years. Started out in retail and now I’m in commercial and industrial applications. As for industrial applications, solid tires are quickly increasing in their useage. Forklifts, front end loaders, and skid steers are ideal platforms; low speeds, stable under extreme loads, and puncture resistant. Most are press-on applicatios.
Tweels have yet to really catch on due to the limited number of producers and high prices. They tend to be more forgiving then the solid tires, but my experience is that they still get destroyed by careless operators. Michelin had even pitched this as future technology for use on cars and such, but I think they still need to research this a lot further before it becomes a practical option for consumers.
As for a SUV/car/light truck application, it would destroy the suspension and drive train in no time fast due to the extreme weight and rigidity.
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After speaker success, I decided to go for the IsoAcoustics under my turntable. The much cheaper pro ones, about $100 for 4 of them, which are pretty much the same but less shiny (a good thing). They can’t take spikes, so I had to blow another $15 on some 10mm black acrylic discs.
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I think this is an interesting technology to observe and see how it unfolds. But for the time being, I’m leaving my nitro filled Pirelli’s on my XC70
One other thing about these Tweels, there’s more nooks and crannies to clean. I am not a fan of that at all. I’ve never been a fan of spoked wheels either.
How do you like them? I have both and could not tell much difference between the pro and shiny ones.
They work. The floor is springly and I can walk around happily, plus with them under the speakers as well (the larger Iso-Puck 76) they are well isolated from each other.
I called IsoAcoustics and they freely said that the consumer market prefers the metallic finish, there are small design differences, but the effectiveness is marginally different and plenty of consumer users use the pro ones.
The Townshend Podium does the same job, but is big and ugly and I can’t use my stylus guard with it. It will be up for sale.