04-Mar-2019, 16:11
(04-Mar-2019, 13:21)Confused Wrote: Many questions in one post @awkaplan . I shall try to answer some of them.
Devialet does not impose a 20hz high-pass filter by default. Or at least not on the digital inputs. The RIAA 1976 phono stage equalisation curve does include a high pass filter, intended to remove the low-frequency rumble that you can get with many turntables.
As for SAM, it does provide a degree of bass boost by increasing the gain at lower frequencies. So if a speaker is rolling off by -4dB at 50Hz, SAM will add +4dB, but will ultimately restrict this to avoid exceeding the speakers thermal rating or maximum bass driver excursion. The SAM phase correction works 100% when SAM is enabled, but the SAM % adjustment can be used to adjust the amount of bass gain / boost that SAM applies. As @David A explains above, the room and speaker positioning can have a huge effect on the actual in-room bass response, so the SAM % adjustment can be used to fine tune the overall level of bass to suit your room and taste. One point to clarify, the SAM measurements are taken at close proximity to the speaker using a laser to measure driver movement, no microphones are involved, so the measurements themselves are not influenced by the room. The links to videos below explain this in detail.
https://www.youtube.com/watch?v=AcLYb4sBhwQ
https://darko.audio/2016/09/waiting-for-...ts-samlab/
Upsampling is a very complex topic. Upsampling can be used as a tool to eliminate some of the unwanted side effects of digital to analogue conversion. For example, upsampling to 24/192 is supposed to help remove the unwanted "aliasing" effect created by digital to analogue conversion. This is not a simple topic and relates to the various filters that can be used. As an example, Roon allows you to select four different filters, some software applications such as HQPlayer have many more. I think the filters make only a very subtle difference, so this one is largely to be determined by personal preference or fine-tuning a particular system. Indeed, I know of some that select particular filters depending on the type of music that they are listening to, so there is no absolute right answer here. It is worth mentioning that the Devialet upsamples all digital feeds to 24/192 anyway. One argument for performing 24/192 upsampling in the software is that the Devialet then has to do less work dealing with the incoming signal, thus reducing noise in the amp. This is a controversial area, and I would say the effects are subtle at best, but the is no reason not to experiment to find out what you prefer, if you are so inclined.
Then you mention parametric eq. This is something that can produce some very unsubtle effects! You change the parametric eq, the system will sound different. I have been experimenting with parametric eq, for me though this is to compensate for different recordings. With some recordings, my system sounds superb, just right. With other recordings, it can sound overly bright or thin, so I have some eq settings to produce a gradual drop off at higher frequencies. I am still experimenting with this, but it does seem to work on some of the old 16/44 rips that I have, where the original recording is not the best.
In terms of using parametric eq to make low-level listening sound better, this is something covered by the "Fletcher Munson Curve", which determines how the how human hearing perception of frequency response varies with volume. Or in simple terms, music at low volumes can sound better if you tweak the bass and treble up a touch. This topic is covered extensively on the 'net, so maybe worth some time researching if you are interested.
The Roon parametric eq function is extremely powerful, it is also fairly complex. One suggestion I would make is that you start by experimenting with something far more simple, that is simply using the Devialet's tone controls to tweak the bass and treble slightly. When you start to get some clarity with how this is influencing the enjoyment of your system, then you could move to using Roon parametric eq to fine tune this further to suit your taste and system.
I will sign off by saying that use of Roon EQ and indeed the Devialet's tone controls are for me an interesting area. I have very distant memories as a child of my parents "Radiogram", which featured a "Loudness Button", which invoked some kind of Fletcher Munson compensation, or maybe it just boosted the bass and treble a bit. Then later in life, we had an era when any audio product that featured a tone control was deemed to be inherently rubbish, and the good stuff did not include such nasty devices that would reduce the purity of the signal. Because of this I still feel that turning the treble down by 2dB or something is somehow cheating, but I think I need to get over this, because simple adjustments like this can work absolute wonders with some recordings that I have. For me, it would indeed be very interesting to get a summary from others using the Devialet tone controls, Roon EQ or similar, to fine-tune their systems, what do you use and why?
Yep, a lot to unpack. Thanks for bearing with me. Not sure where I saw the 20hz default in the configurator—could've been a misread. I am familiar with the way SAM profiles are generally created, including the use of laser measurement. Still a little confused about the speaker crossover situation and high-pass filters within the speakers as they interact with SAM.
It's funny, I'm also very reluctant to touch the tone controls within the unit itself. Part of the reason I even started experimenting with the Parametric EQ is that I'm currently doing a few rounds of demos of speaker cable, and while I'm in limbo I have to go back to using my own cables, lower-end AQ, albeit factory-finished and biwired. I was accidentally sent a pair of Shunyata Venoms in an unusual double-biwire configuration, and after a week listening through that much copper I feel like I'm in the penalty box and am looking to reproduce some of what I heard, temporarily.
I've left the upsampling on for the time being, and may experiment more when the next set of demos arrives. Ideally, I'd like to let the hardware speak for itself. My listening area doesn't present much of a challenge, but I may also experiment with convolution and return to the EQ down the road if I'm missing something with my new speakers and cables.
