We give up perspective to avoid tone controls

Hello All,
    There are times when I tweak the heck out of even well recorded music.... Sometimes I listen to music at very low volumes and I max out the tone controls and the ‘compensate’ circuit of my Accuphase E-470. I’m surprised that listening at low volumes and the need to boost certain frequencies hasn’t made this discussion. 
    Also, I feel like I have very sensitive hearing and even at normal listening levels I can’t perceive any degradation to the sound when using the tone control on the Accuphase. I will never by an integrated or preamp without them again.

~Oran

I believe it is all personal Taste.
Our ears are as individual as we are.
Everyone is different.
What you like the sound of i may not etc.
Also a big factor is your Audio Knowledge and experience.
A well seasoned recording studio engineer would pick out stuff that we would not even think of.
A lot of factors to consider.
One is Volume.
What your listening to another.
Your systems EQ changes with volume.
Read about The Fletcher /Munson Equal loudness curves.

Hey Vintage Heath, good for you. I like your keep-it-fun attitude! 

When first starting out in what may be considered higher end equipment, I was told EQ is a four letter word. After years of incorporating different room treatments and still having issues with too much mid bass, I decided to try a Samson S curve 231. It's helped tremendously. I know it's best to have as little equipment in the signal path as possible, but for me, it's really helped. 

After 5+ decades of heavy DIY audio experience, I conclude that conventionally implemented (preamp) tone controls introduce too many inaccuracies to prove generally acceptable. Virtually all such circuits cause significant channel tracking imbalance, and some add other phase and distortion anomalies that seriously degrade any aural benefit.

In those cases (like mine) where the primary objective is to implement convenient variable control of the low bass-to-main speaker balance, there's a better/cleaner way: Add a pair of (sealed, not ported*) self-powered subwoofers. Operate them in "bypass mode" (internal low-pass filters deactivated), and control them through an EXTERNAL active crossover (Linkwitz-Riley, 4th order) control unit, e.g. Marchand's XM66. Fully variable control of the crossover point AND the main/bass input level is then available at a convenient single, central location. This makes it easy to set/reset your desired main speakers-to-subwoofers output ratio, using accurate plus/minus 1dB stepped attenuator front panel level control switches. It's an easy, elegant, and very accurate way to control the relative low bass-to-main speaker acoustic blend—and you can alter or restore a desired mix with optimum convenience.

*Sealed-subs can be more accurately phase-matched with your main speakers than when using ported subs. It's also helpful to use sealed (not ported) main speakers.

Virtually all such circuits cause significant channel tracking imbalance, and some add other phase and distortion anomalies that seriously degrade any aural benefit.

vtvmtodvm:
That's pretty breathtaking in it's scope. While I do agree: I wish manufacturers paid more attention to the quality of the tone controls, in general I have to disagree. I think the convenience factor needs to be weighed in. Like loudness controls for instance, being able to "convert" my speakers from medium to low-volume listening is a good thing, not to mention transforming them into party mode speakers.

Also, placement. Being able to adjust for speakers too close or too far from the walls is a case where tone controls are a lot cheaper than buying new speakers.

*Sealed-subs can be more accurately phase-matched with your main speakers than when using ported subs.

Since the ports contribute only to the bottom end, and the phase matching must occur at the top, I don't follow your logic.

There are many who feel sealed subs have the best transient responses though. In my experience, this is more a matter of integration and EQ than any absolute technical superiority of port vs. sealed.

It's also helpful to use sealed (not ported) main speakers.

This is often true. This is what THX tried to do with the satellite specifications, and has to do with phase and amplitude matching. They were big fans of LR4 alignments, and sealed sats + 2nd order HP electrical helps achieve this rather consistently.

One of my full-range listening systems is my home studio where I have access to 3 different hardware equalizers, each in the 3k-$5k price range, (no not graphic EQs).  They all sound great, and they each sound different from one another.  Each can make music sound better when it's lacking in some area.   I will use EQ when playing vinyl that's had the lows and/or highs rolled off to fit the format..... and make mediocre pressings sound far more entertaining.    So what's the alternative?... To sit there bored to tears with flat sound and my purist morals intact?  Life's too short for boring sound.  My bypass button works just fine for the great stuff.

I have this problem with my main speakers-not my subs and dot ant to lose my good sound, going thru my subs as a crossover. I have a Casablanca 3, (just taking up space) I guess I could put in the tape monitor loop?? It's very versatile. Guess I need to invest in a good parametric EQ. I'm considering building a new sound room, if I move. Don't have the bucks to do it the acoustic fields way. Think I'll start a new thread. 

 @ erik squires—Phase matching of subs-to-mains should always be optimized at the applicable crossover frequency, and the measurement point to define the match should be located (precisely) at the intended listening position. When ported speakers are involved, crossover frequency waveform propagation becomes more indistinct, diverse, and increasingly affected by room-induced peaks and nulls that muddy the matching precision. (I use instrumented-means to accurately accomplish phase matching. If interested, request my related white paper. I am at geyer.bryan@gmail.com)

Sustained wide area phase matching is a fantasy, and any expectation that synchronized phase can persist over more than a small part of the home listening room, or beyond the limits of a given test frequency, is misplaced. This reality should not be construed as a significant shortcoming; refer 4.8.1 of Floyd Toole’s epic “Sound Reproduction”, 3rd edition (Routledge, 2018, ISBN 978-1-138-92136-8).

Phase matching of subs-to-mains should always be optimized at the applicable crossover frequency, and the measurement point to define the match should be located (precisely) at the intended listening position.

OK, with you so far...

When ported speakers are involved, crossover frequency waveform propagation becomes more indistinct,

<< cough >> No it doesn’t. The crossover frequency doesn’t move around depending on the sub's cabinet type.

diverse, and increasingly affected by room-induced peaks and nulls that muddy the matching precision.

Which is why you should deal with the sub’s overall response first, and then the crossover matching second.

Peaks and valleys are easily dealt with by use of bass traps and EQ, regardless of whether the sub is sealed or ported. Again, if you like sealed, that’s fine. However, the crossover frequency and how it matches the subs is at the top of the sub’s range, not the bottom, where the room modes are (hopefully) less frequent and severe.

What often confuses listeners is that the same speaker, ported, will go deeper, and therefore is more likely to run afoul of those room modes. The peaks and valleys you mention.

Sustained wide area phase matching is a fantasy, and any expectation that synchronized phase can persist over more than a small part of the home listening room, or beyond the limits of a given test frequency, is misplaced.

Which is weird, because this is the very opposite of what you are attempting to discuss in your first sentence. It’s also a point no one has brought up, but since you have ... this all depends on how co-incident the sub and main speakers are, the measurement area, and the crossover frequency. If the sub is directly underneath the satellites, this is hardly an issue in most listening rooms.

At 80 Hz, 1 wavelength is 14 feet long. A quarter of that is around 4 feet. That’s how much the distance must vary from ideal before you have significant change.  So if you have two subs and satellites are right next to each other, so that in the center of the room, they are equidistant, you'd need to find a place in the room where the sub was 4 feet closer  or further away to you than the satellite.  On the other hand, if you use a single sub, located in the center, then yes, listening directly to the sides is probably this far. 

And like I think you are trying to get to, those peaks and valleys will make a much bigger deal than microsecond phase matching of the sub. However, they are just as hard, or easy to deal with in a ported or sealed speaker which covers the same range. So far it seems to me you are conflating phase/amplitude matching at the crossover frequency with the rest of it, which I don’t really get.

Best,


E

E—Thanks for such comprehensive clarity; I generally concur. But my simple comment (that it's easier to phase-match subwoofers-to-main speakers when all speakers are sealed, not ported) was never intended to apply to idealized environs filled with bass traps and EQ correction. Nor did I intend that phase matching be conflated with time-of-arrival correction. It's generally not possible to accomplish the latter in the average home living room because decor dictates that the subs go into the room corners and the mains go up front, more centered. Given these typical limitations, it will always be easier to synchronize the phasing (at the xover frequency, at the prime listening location) if the speakers are sealed—not ported.

The extent of the phase convergence will be determined by the prevailing acoustics. In my own living room (no bass traps, strict WAF control), measurements indicate that closely matched phase won't prevail beyond a few feet from the prime listening location. Regardless, accurately phase-matching the subs/mains yielded significant audible improvement, and an instrumented means to accomplish the match was lots less tedious than doing tweak-and-listen trials.

I generally don’t feel the need for tone controls in my system. I have a nice sounding room, nice accurate speakers, but my CJ amps and pre-amp add a touch of romance.

But I also sometimes use my old Eico HF-81 14W integrated amp. It has basic treble/volume control and I have no problem using them. I used them to dial in the sound I like for that amp. (But once dialed in, I don’t feel any need to bother touching the tone control again).

I personally don’t care to get in to the mind set of trying to tweak my system to every, or most recordings. That to me is too distracting.

That said, the ONE area in which I wouldn’t mind some tweaking control is in adding subwoofers to my system. I haven’t got them set up anything near perfectly, but I love the effect of full range for lots of tracks, but the occasional tracks I prefer without subs. I’d like a pre-set or two that dialed back the sub, or at least the lowest frequencies, at the touch of a button. (And if I implement the DSpeaker Anti-mode unit that I have, I should have such a control).

prof—I'll try to help. It sounds as if you've got TWO separate subwoofers. Correct? What make/model are these subwoofers? And are these subs self-powered, with their own (independent) internal power amplifiers? If not self-powered, how do feed audio signals to them, and from what source?

I use 2 unobtrusive beautiful sounding REL subs (inexpensive bought used) and their volume pots are accessible due to chicken head knobs, and until recently they were my only "tone controls"....and that was fine, and mostly still is. I have a Schiit Loki that is also unobtrusive and seems to have zero impact when bypassed (click it on and off and you can see what that's all about...no sign of it). Other than the fact that, in my case anyway, it makes for longer cables runs to the amp (and is single ended only). I checked very carefully to see if the longer cable runs (a couple of meters instead of previously one) had any negative effect on my preamp-to-amp signal and was happy to notice it doesn't. In any case, those who are anti "DSP electronic nanny" (they remove some of the soul from music, and I should know as I have no soul at all) should order a Loki immediately. Although it stays bypassed most of the time, it's an extremely useful little el-cheapo gem. Look for a balanced version eventually, although that should be somewhat more costly...still...

vtvmtodvm,

Just noticed your reply.

I have two JL Audio E110 subwoofers, and the JL Audio CR-1 outboard crossover, as well as a DSpeaker Anti-node sitting in a box if I want to use it.

I have tube preamp, tube monoblocks, and intend to use the crossover to send signal to the mains and sub.   If I feel the need, I'll use the anti-node on the sub frequencies (I don't care to digitize the entire signal if I can help it).

prof—I certainly CAN help you with this; I own a pair of JL Audio E110 subs myself, and use a Marchand XM66 active crossover, which is functionally equivalent to JL Audio's CR-1, but lots cheaper (has lower quality internal components). 

However, I now have a dentist appointment to attend, and it involves some major stuff, so I probably won't be in shape to respond further today. I'll get back to you tomorrow for sure.

prof—OK, let's go: First, make certain that both of your e110 subs are free of a common component failure (bad or intermittent input level pot) that plagued many e110 plate amplifiers. Turn the input level gain all of the way down, and connect an input sine wave signal of 80 to 100 Hz at 1 Vrms to an input jack. Then turn on the e110 sub and slowly, smoothly advance the input gain pot to assure a steady increase in the acoustic output. If operation is normal, good. But if the output gain is not seamless—if it suddenly jumps to full gain—you have a JL Audio warranty repair claim to lodge.

( I purchased my own e110 subs in mid-2016. One plate amp input pot went bad a year later, and the other plate amp went bad in early 2018, This is a known issue to JL Audio. If your pair is affected insist on free warranty repair, and firmly insist of free pre-paid shipping. Do not return the entire e110; just ship them the plate amp. Disassembly is obvious.)

Let's get to setup:  (1) Placement: In most situations, the best acoustic results will be assured with the subs flanked outside the main speakers and near the room corners. That's also consistent with most decor options.  (2) Crossover Frequency: Pick your xover point based on the capability of your main speakers. If you're using small mini-monitor main speakers (like my own Spendor S3/5R2 units, with little 5.5 inch Ø mid/woofers), pick a high xover, I use 94Hz. If your main speakers are big floor-standers, use 80Hz. And don't go any higher than 96Hz, nor any lower than 80Hz.  (3) Set your (absolutely terrific!) CR-1 active external xover controls at the desired xover frequency (set subs/mains same), select full 4th order Linkwitz-Riley 24dB/octave operation, stereo operation, and set the CR-1 balance control at zero, straight-up. Set both of the CR-1 damping controls at ≈ +2.  (4) Set the e110 subs for (manual) power off, polarity switch at 0, phase angle set at 0˚, and select "bypass mode" operation, thus assuring that the internal low pass filters will be bypassed and out-of-circuit. All subsequent crossover control, except for initial setting of the e110's input gain and phase angle adjustment, will then be accomplished at the CR-1. This represents a major convenience advantage: It will allow you to readjust the subwoofer-to-main speaker acoustic output ratio from one centralized location—no need to crawl to each individual subwoofer.

(5) Verify that your preamp/main system volume control stereo outputs are fed to the CR-1 input jacks, and that the CR-1 high-pass stereo outputs go to your main speaker's power amplifier, with the CR-1 low-pass stereo outputs routed to the left & right channel e110 subwoofer input jacks. (Do not use a Y-connector at the inputs; just route the CR-1 low-pass left output to left sub's left input jack, and the right output to the right sub's right input jack.)

(6) Adjusting Subwoofer Input Gain & Phase-Angle: The desired objective is to…
(a) Set the subwoofer's input gain so that the acoustic output level of each subwoofer will be +3dB greater than the related main speaker's acoustic output at the specified xover frequency, at the prime listening position.
—and—
(b) Set the subwoofer's phase angle so that a xover frequency sine wave signal from the subwoofer is fully phase-synchronized with an equivalent signal from the related main speaker AT THE PRIME LISTENING POSITION.
Both of these adjustments can be readily accomplished in a direct, single step process. First, drive BOTH main speakers alone (subs off) to a high acoustic level (at xover frequency, SPL 82-to-84dB, C-weighted), as measured at the prime listening position, from a fixed sine wave signal source, using the main master volume control to adjust the output level. Then, set one sub (other sub off) for REVERSED POLARITY operation, and turn that sub on. Assure that the master volume control is at the same (loud) level as previously set. Now, ALTERNATELY adjust the subwoofer's input gain and phase angle controls to achieve a minimal null of the combined acoustic output, as determined at the prime listening position. This null will be very sudden, distinct, and pronounced. Alternately adjust both input gain and phase angle for minimal output. When done, switch off the subwoofer and return the polarity switch to its normal zero position.

Repeat the above procedure for the other subwoofer. When done, assure that both subs are properly reset for normal polarity output, and that their power switches have been reset for normal "auto-on" mode operation.

I have available a detailed two page white paper that describes the above process in detail. It also provides info on how to accomplish this setup with a basic dynamic microphone and the use of some simple instrumentation. This instrumented-means for handling this job provides helpful visual guidance, and eliminates the need for any assistance when conducting the testing. I can e-mail a pdf of this paper to you if you will provide me with your e-mail address. My own e-mail is: geyer.bryan@gmail.com

Advise if you have further questions.

Brevity warning: Buy a sub, adjust the phase if possible so it works properly, move it around until it sounds good and turn it up or down to blend with the main speakers. Done. 

@vtvmtodvm

I completely missed your extended lesson on setting up the JL subs!!!!

Thanks a billion for taking that time! I will go through it more carefully when I’m about to set up the subs. I also have the Soundoctor tracks and the set up advice pages that came with that CD.

Every time I think "ok, this weekend I’ll set up my subs" I look at the steps to get it right (using a crossover) and it looks so damned daunting I can never find the time. I first tried using the high level input method, taking a line off my speaker terminals. That didn’t seem to work so well (lost dynamics and tone). So I went on to buying the CR-1 crossover to "do it right" as all the subwoofer fanatics insist.

The problem is once I’m doing things like crossing over main speakers way up at 80Hz it seems like I’ve then tossing out what the speaker designer did and I’m designing a new speaker. And who the hell am I to design a speaker? It takes years and years for speaker designers to learn how to conquer crossover design, and I’m going to toss out what they did and do better over a weekend? Doesn’t compute for me. The potential for utterly screwing up the sound seems massively more probable than making things better.

But...somehow others do it all the time. So...in I plunge...at some point.

One issue for me is all my source equipment is down the hall from my speaker room, so I can’t easily have the CR-1 in the same room to dial things in. Thus I’ve bought long interconnects to be able to bring the CR-1 into my listening room just for the set up procedure.

At the moment I do have my two JL subs flanking just outside and behind the main speakers by a couple feet or so. Given the limitations of my room space, that is literally the only option EXCEPT I’d actually like to keep the right sub where it is and place the other on the room diagonal which puts it behind my listening sofa to my left side. Supposedly this is one of the good set ups for smooth bass and the other bonus is getting one more sub out of sight (I hate the look of subs).