Bass management with stand alone preamps

it’s interesting there hasn’t been a Linux-type standard that breaks the rules within the rules being put out there for others to use.

+1  big fan of Linux

Thanx Chris. This is the kind of thing that happens when there is not a strict industry standard. It seems the only standard here is the plug and jack. Planned obsolescence. Now everyone has to buy a new TV and player to stay up to date. Chris, is any of this backwards compatible?  

Thanks for that write up, that’s pretty interesting. I’ve seen at least two companies, McIntosh and PS Audio , come out with their own proprietary methods of passing DSD to their own equipment. I’m guessing this is not an easy thing to do , but it’s interesting there hasn’t been a Linux-type standard that breaks the rules within the rules being put out there for others to use. 

Esthlos13,

Great question about HDMI...

The new spec coming for next year is 2.1 which deals with passing 8K for video.  There are other factors involved, but that is the primary.  You can explore it at:

https://www.hdmi.org/manufacturer/hdmi_2_1/index.aspx  

Keep in mind; Video (TV's) will get the new chipsets put in for 8K TV's first - that's somewhat happening now.  Next will be the source components.  And, finally, the receiver manufacturers will get them last, which as of right now for them, sets around summer of next year when the chipsets become available and that means new receivers will start getting them in the fall/winter 2020 and/or first two quarters of 2021.  

A big reason why higher end manufacturers don't put in HDMI even (Audio Related) is because of the challenges of units talking to one another, the (EDID), and with all the variations of HDMI out there between different brands of products, it can simply pose a lot of problems down the road.  

The single biggest reason is; that in order to have access to the latest chipsets, manufacturers have to buy a certain MOQ (minimum order quantity).  It doesn't have anything to do with how much you're willing to spend or can spend, they simply don't care, it's about volume.  There are only like two or three companies you can deal with overseas to get these chipsets.  That's why many products come out of the same factory (Onkyo/Integra/Pioneer, Denon/Marantz, Arcam, Anthem in one, not necessarily all those brands together, but another factory with Sony, Yamaha, etc.).  Each manufacturer designs things to there own specification, but there in lies the other major issue.  If you want the latest HDMI, you can't just purchase them and they send them to you, it means you have to build that piece of gear overseas in their factory - which higher end products don't want and will not do. 

If there is HDMI in higher end pieces, it's only because it's finally been available long enough to where anyone can purchase them which means they are older and could have issues.  Manufacturers have to forecast how many units they think they can build and sell and have to purchase extra because they aren't really "repairable", they have to be replaced.  When manufacturers spend a year or more in development of a piece of gear, whatever the piece is, and then know they're going to get older HDMI chipsets, it's hard to come to market with a piece that's essentially become a boat anchor the day it launches.

I hope that clears up a bit of the confusion around HDMI?  I've also read a lot of misinformation in this thread about room correction and bass management.  If you have any questions in regards to that, please don't hesitate to reach out in a direct message. 

Thanks,
Chris

Esthlos, The receivers and Blu Ray players are aimed at theater folks and the DACs and Preamps are aimed at Audio folks.  

Interesting thread so far.  I’ll be playing with the bass management settings more in my processor based on some of the comments here. 

One other question - with the room correction equipment I’m holding it’s best to feed a pure digital signal but in the case of sacd none appear to accept hdmi DSD stream to avoid an extra d/a conversion.   Why are inexpensive receivers and Blu-ray players able to support DSD over HDMI but ultra pricey DACs or preamps rarely offer it?  

I scrape by with 2 subs, and think the array thing is cool but impractical for my current setup...I also am a Schiit Loki advocate, used rarely but it's there when I need it. Note that an array shouldn't exceed 14 subs as that is, well, excessive. 13 is the max, look it up. Or no...don't look it up.

No, I meant with the sub woofer.

Yes- Sound Lab used to make the B1 subwoofer, which was a large electrostatic panel. 

These are the best ESLs you can buy at this time.

Agreed. IMO they are also one of the top five speakers made anywhere.

Electrostatic loudspeakers. Martin Logans are ESLs from about 250 Hz up most of their speakers cross over to standard woofers. I think they still make one full range ESL. ESLs run on a different principle than regular dynamic divers. In the middle of the speaker is a charged mylar diaphragm. Charges up to 4-5  thousand volts are not unusual. On either side of the diaphragm is a "stator." This is a wire or metallic grid that is driven push pull by the amplifier through a step up transformer converting current to voltage. Like charges repel opposite charges attract. Thus the diaphragm is moved back and forth to the music. An entire 8 foot by 2 foot diaphragm weighs less than the voice coil of a 10 inch woofer. Every molecule on the diaphragm is driven and controlled 
by the amplifier. There is no cone flopping around.  The only disadvantage is that by design they are much larger than regular dynamic speakers. I believe their size is an advantage especially when they stretch from floor to ceiling producing a perfect linear array at all frequencies. They are typically dipoles ( they produce sound 180 degrees out of phase from both sides front and back.) Which makes low bass difficult but a linear array dipole is the best way to deal with room acoustics because of their radiation characteristics. There is no dynamic loudspeaker that can better the performance of a linear array ESL especially when they are mated to an appropriately designed sub woofer system. It is not IMHO either. Anyone who hears such a system is dumb founded. Anything from a single Block Flute to the Pixies is produced with a dynamic realism that I have not heard produced any other way.
Google soundlabs speakers. These are the best ESLs you can buy at this time. 

What are ESL? Martin Logan speakers?

No, I meant with the sub woofer. I know Dr West. One of my heroes. He has kept the faith and the flame alive.
Making an ESL sub woofer that you could use in an average room is a tough one. My own feeling is that ESLs having to be dipoles have never been good at deep bass and forcing them to do it just ruins the beauty of what they do everywhere else. Any dipole in an enclosed space is going to have the same problems but ESLs do not cross over to other drivers
making it worse for them. I would not ever use a full range ESL without a  sub woofer system unless you just listen to string quartets.

^^ I don't see the B1 listed there either... Dr West is the designer of the Sound Lab loudspeakers.

They are not listed on the site. At least I have not seen them. What does he do?

They project a large as life sound stage. With woofers set up like this the bass sounds just as big and powerful as the SoundLabs except the SoundLabs become cleaner and are capable of another 10 db or so if you care to crack all your windows.

:)

Dr. West has long been an advocate of such as you probably know. Have you ever tried his ESL subwoofer system?

I can do better Atmasphere. It is not far off the distributed array idea but is a more powerful. I have mentioned it before on this site. I have linear arrays which project power differently than point source speakers. Their power drops off at the square of the distance. Point sources drop off at the cube of the distance, much faster. The distributed array idea is using 4 rather small point sources. I use 4 woofers set up as a linear array using the walls as boundaries. The two end woofers must be in the corners and none of the woofers can be further apart than 1/2 the wavelength of the highest frequency they are expected to reproduce. All woofers are right up against the front wall. The two inner woofers are facing each other so that their drivers are right up against the front wall. What you get is 4 woofers acting as a single driver. Since they are using three walls as boundaries the only primary reflection is the rear wall which is delayed and down in volume. I built this house and purposely designed it so that there is essentially no rear wall. The end result is very powerful base that matches the output of my ESLs without any standing waves. You can walk through the room and the base response does not change until you get right up against a lateral wall. This is with room control disabled. The ESLs have their signals delayed by less than a millisecond so that the woofers are exactly in phase with the ESLs. I cross over at 125 Hz 48 and 24 db/oct. You can not hear the cross over. It is entirely seamless. Is is much harder to match sub woofers with speakers at lower cross over points because of the longer wavelengths. 100 Hz is around 10 feet. 20 Hz is 32 feet. You try and cross over at 60 or 80 hz and you have to move your speakers 1/2 way across the room unless you have room control that measures the delays and accounts for them. Most don't yet people are trying to cross at 80 Hz and do not understand why things don't sound quite right. Properly set up you should not be able to tell at all  that there are sub woofers in the system. You should be presented with one powerful whole. I have yet to see an analog system do this. They can come close but not quite there. Digital bass management and phase or time management seem to be crucial to make this work correctly. I am sure you have heard SoundLabs speakers. They project a large as life sound stage. With woofers set up like this the bass sounds just as big and powerful as the SoundLabs except the SoundLabs become cleaner and are capable of another 10 db or so if you care to crack all your windows.

@mijostyn You are correct in what you say, but if you use a distributed bass array you don't have such profound problems with the bass changing as you move the speakers; much of that is due to standing waves. So this makes getting the bass right a **lot** easier!

Atmasphere, I think you are confusing room correction with bass management. Bass management supplies cross over points, slopes and outputs for sub woofers. Room control without careful woofer set up and acoustic management in the room just shifts the comb filtering around at the cost of a lot of power. I do not like the term room control. I like speaker control better. It is to fix response abnormalities of the speakers or woofers in the position they occupy in the room. If you move a speaker from one point in a room to another its frequency response will change. The most important function of room control is not to make everything Flat. Flat actually sounds awful at volume. Way too bright. It is to make the response of the speakers exactly equal at all frequencies. The result of this is razor imaging. If frequencies vary in volume one side to another you smear the image. Then if you have a good unit that allows you can create target curves and tailor the frequency response to your liking. You can also create target curves for specific purposes. I have a curve with a 3 db notch filter at 3 kHz which I use for violins and female voices that are too harsh. Once you are in the digital domain you can do anything you want. Those that think "room control" is only for bass are sadly mistaken. Audiophiles that hear this in action on a good set of ESLs are dumbfounded. The improvement is such that I do the unspeakable of digitizing the output of my phono preamp and input it to the TACT. 

esthlos13, yes Trinnov does 8, 16 and 32 channel units using the same system. The Amethyst is the only two channel unit they make. They make a stand alone room control unit but the Amethyst adds a lot of important features like digital bass management, a great DAC and even a phono stage which frankly I would not use. I need two phono inputs and I'm a dyed in the wool ARC guy when it comes to phono stages. But, if the turntable is a minor part of your system and room is limited it is probably fine. Lyngdorf is an out growth of TACT Audio. For some reason Lyngdorf does not offer a stand alone 2 channel processor/preamp which is a shame. The TACT 2.2X was at the Apex of TACT's development and it is an amazing processor/preamp. Built like a battleship it has very high resolution room control, unlimited target curve management and the best bass management I have ever seen. You can change cross over points and filters on the fly and choices are unlimited. High pass and low pass filters are set independently. You want a high pass filter of 97Hz @ 80 db/oct? Just dial it in and hit the go button. It has Dynamic Loudness Control. A series of target curves simulate the Fletcher Munson curves at various volumes and it drifts from one curve to the next as you change volume. You set the curves to be flat at the loudest volume you listen too then as you drop the volume the compensation increases. So, as you drop the volume the frequency balance of the music does not change down to -48 db. None of us ever liked loudness compensation because it only worked at one volume. It was off everywhere else. This system is  great. The music just sounds the same no matter where you set the volume control otherwise it is totally invisible. So, why did this unit not succeed? As you might have guessed I have one. TACT (Boz) decided to market his units directly. He did not use dealers. He was doing this to try and keep prices down. In his genius mind he did not realize that every one was not as educated in DSP as he was or just not as smart. The 2.2X is anything but user friendly. If you put the microphone close to any object funny things would go wrong with the measurements. You had to know when it was screwing up or you got really sick sounding compensation filters. The user manual sucked and the learning curve was steep. He had no dealer support so he got buried in phone calls and problems. His units got a bad reputation and finally Boz just disappeared. If you are techish and computer savvy and see one of these on the market for anything less than 4 grand buy it! You will have a blast. 

The problem that you often run into that makes people think they need bass management is something called a 'standing wave'. This is a bass note that is of such a frequency that when it bounced off of the wall behind the listener, the result is that there is a bass cancellation at the listening chair.
This makes the listener want to turn up the bass, which might come in the form of 'room management' or 'bass management'. If you have a high performance system, both will degrade the sound.


Another issue is when the standing wave is in phase with the incoming bass, creating something called 'super position'; IOW a massive bass output at a certain frequency. Both can occur at the same listening chair.

If you have this problem, room correction might be able to correct the super position but not the null created by the standing wave. No amount of power corrects that and room treatment doesn't work either.

The solution is called a 'Distributed Bass Array'; the best example being the Swarm subwoofer made by Audiokinesis. The idea is that two subs go near your front speakers, the other two are placed asymmetrically in the room boundaries to the left and right of the listening chair (placement is not critical). This breaks up the standing wave and gives you even bass distribution throughout the room.


Problem solved: no need for 'bass management'. Just a second output to drive the subwoofer amp.

I always laugh when people bash tone controls but then roll in different tubes to flavor the sound. 

Is this Trinnovs first foray into two channel?  I hold them mostly as a home theater type company.  

mike, the Trinnovs fan is dead silent. Very slow speed. It does tell you how much computing power they have in there. A Lot. To call it a preamp is an understatement. It is the best room control available at this point, it is digital bass management for two channels although not quite as powerful as the TACT bass management and it is a DAC. It is also $11,000 with microphone. 

Audiophile preamps with full bass management are relatively rare. Some have been mentioned by others. A few more are

• Anthem STR Preamp (also STR Integrated)
  
• miniDSP SHD
• Classe Delta Pre, not yet released. (Its predecessor, the Classe CP-800, has bass management for 1 or 2 subs.)
• Trinnov Amethyst (warning: has a fan)
• Legacy Wavelet
• NAD C658D (though the bass management firmware may not have been released yet)
  

As noted, many audiophiles (not me) think that DSP, bass management, or any type of tone controls limit the sound quality. In my opinion, the newest DSP products are quite good, and in many practical situations, the benefits far outweigh any drawbacks.

Parasound P7 and others include it.

 Thanks for the replies. For clarity the marantz is a prepro ( I have all my equipment listed in the virtual systems) and from reviews I’ve read holds its own as a two channel preamp but I have been interested in how bug a jump it would be from my current setup to say a levinson 585 integrated  and then from that to a separate levinson pre and amp combo.  The integrated is significantly cheaper, on audiogon probably 1/3 to 1/4 the cost of a comparable pre/ amp combo not factoring in an extra power cable or two and more interconnects.  If one should room isn’t perfect/ treated is this all a waste of $ until ?

Here are a couple.  Also, Micromega make preamps with dual sub outputs that can be used with an DSpeaker Antimode 2.0 for bass management.  

http://www.dspeaker.com/en/products/anti-mode-x4.shtml

http://lyngdorf.com/mp-50/

Yeah most separate preamps omit that because people getting into separates tend to be chasing ultimate performance which tone controls are not. At all.

Stepping up from a receiver you’ll do well to look at integrateds as the next logical step and far more sound quality for the money than separates. Just get one with a single pre-out. All you need.

Subs definitely help but most still have not figured out the answer is several not one. At low frequencies you get a lot of bass modes, which is actually good, you want more, as more is smoother. So its actually better to run the main stereo pair full range, using whatever bass output they have to contribute to that smoothing. Then use four subs spread out asymmetrically around the room. These four can be anything from four speakers with one amp to four separate powered subs, or anything in between. Search for Swarm or distributed bass array and read the threads to see how deliriously happy we all are who have taken this approach.