It may come as a shock to audio purists but part of the work of a crossover is level matching as well as tonal adjustments of individual drivers. Ahem. That's what we call equalization.
This is true whether the speaker uses active or passive crossover, and may be in place just to adjust phase matching in the crossover range.
Also, curiously, while companies may brag about the number of parts in their crossovers, more parts does not indicate more quality. It may just indicate more equalization had to be done to the drivers to get them to match.
@elliottbnewcombjrI’m with you 100% on the AR’s, I used to listen to the Nightbird on AR 4’s. I restored the 2 AX’s and they help reinforce that hi-fi hasn’t changed as much as some people think in the last 50 years. :-) I had to recon the woofers, but the mid and tweeters were fine. What tweeters did you choose to replace yours with and how do they compare with the originals?
nice thread Nigel and I like your blog, but I wish it were a little easier to navigate the related articles in the order in which you wrote them. @erik_squires DIY And another nice layer of fun to this hobby and can save a heck of a lot of money.
Eq is the great equalizer. It’s true. Most all room acoustics + imperfect gear performance means things will almost always come up short to some degree until some form of correction is applied. Not only that, but chances are you won’t even know it until things are finally corrected properly and compared.
I would have a very difficult time replacing a variable L-pad instead of just soldering in fixed value resistors. I’ve seen too many of them go bad. Maybe with high efficiency horns that have very little power applied this could be reliable, but not for me.
One theme that comes up a lot when I look at old speakers and the crossovers is that we have much better tools but also different tastes in sound reproduction. Part of what makes new crossovers (especially for Infinity) better is we have tools to simultaneously track impedance and frequency response. Part of it is that sometimes (ahem, Infinity) makers just didn’t care that much about slapping in different drivers. It’s also true though that our listening tastes have changed and mastering engineers along with them.
Then there's the Kef Reference 1 Meta and..... WTF????
I just restored two pairs of them. 1st sounded so good I got a second pair. restored the crossovers and replaced the L-Pads for tweeter and mid volume adjustments. they sound terrific, using in both my office and garage/shop systems.
2nd pair came with new tweeters, I replaced the tweeters on the 1st pair.
I have Altec 604Cs. Good speakers but they were not known for the crossover. I got a pair of Mastering Lab crossovers and had them refurbished with new caps. They have mid and upper shelving. Made a difference.
@dougsatI agree. Since building two pairs of open baffle, single driver speakers with no crossovers, I have found that they have virtues that sit them equal to my LS 50s, Klipsch heresy, ones, and AR 2AX’s. I also have measured my hearing and have a slight rolloff beginning at 4000 Hz and continuing through eight and above. Using Roon, I crafted a compensation curve and have been switching it in and out and come to the conclusion that I rather like it on most recordings. So a “flat response “is appealing in some cases butI have found that there are also things to be gained by allowing one self to move away and explore other avenues.
Although many people attest that the analog EQ does not alter the sound trait in general, I am suspecious if that is true.
@lanx0003- Fan though I may be of tone controls, this is not the blanket statement I would make. There are in fact bad tone controls and bad EQs. Sometimes this happens when a manufacturer takes excellent care in the audio circuit, but skimp in design on the extra parts for the tone controls. I had a Parasound P7 that was like this. An otherwise excellent multi-channel pre with a veil that would come over it when tone controls were engaged.
That’s one of the cool aspects of outboard actively configured speakers and controlling the filter parameters with an external DSP at the listening position, on the fly from your network connected laptop; every filter tweak here is done via the already installed digital crossover, so no added tone controls other than what was there actively to begin with - in the digital domain, and with all filter parameters at your fingertips to be adjusted individually. I still prefer going about the settings manually with the aid of measurements, but with a good microphone and digital correction software this can also be done "automated" in both the amplitude and time domain. Have a bunch a presets made, and compare the different equalizations/adjustments to each other. That’s "tone controls" par excellence from my chair.
The prime takeaway here is tailor fitting your speakers to your room and your taste from the sweet spot. Vital aspects of setting the filter parameters aren’t "taste" per se, but the minute fine tuning from that framework I believe mainly is, and is where those subtle treats are found. I’ve never much cared for slightly tilted up highs and lows (kind of a mild loudness effect) which may evoke a "likeability" to the sound, certainly at lower to moderate SPL’s, but is rather more drawn to absolute coherency and a strong center core/sphere - perhaps something akin to (a more hypothetical) widebander or Quad-like ESL (i.e.: acting as a point source) on mean steroids, or the "musical monitor."
When I auditioned it, I primarily used the low end adjustments but unfortunately it also affected the high end, making bright recordings sound brittle. And I’m not going to use an equalizer to correct problems introduced by the equalizer. I was disappointed. High quality equalizers shouldn’t do that.
Digital eq is the way to go for most. Studio quality PEQs can sound great but are best used for production, not reproduction. Most studios stopped using room eq long ago because of the issues you mentioned.
Although many people attest that the analog EQ does not alter the sound trait in general, I am suspecious if that is true. Essentially, all analog equalizers were electronic circuits with inductors and capacitors which shift the phase of AC signals passing through them to alter the frequency response in different bandwidths. These physical electronic components have the potential to influence sound quality as @mashif has mentioned. For instance, a larger capacitor tends to perform better than its smaller counterpart, producing a bolder and cleaner sound.
On the other hand, the PEQ allows for the adjustment of the Q factor, enabling tone shaping. In contrast, analog EQ is fixed with a Q factor usually set around 1.5. When used judiciously, the digital EQ tool tends to do a better job of tweaking the sound to my liking compared to analog EQ. I rarely notice any degradation in sound quality with the digital EQ.
It affects the sound alright...It fixes Bad recordings......Listened to a Doors Live album last night...Weak bass and a little bright....Loki fixed it...Sounded great and great music that’s now very listenable when it Wasn’t before. Makes sense....yes and it doesn't affect the sound when you turn it off and the signal just runs thru the turned off unit...that's the way Schiit designed it..call them.
I should add that I tried a Schiit Lokius in my system. It’s not bad, but it does change the sound even set flat. The bypass works, but engaging it immediately affects the sound. I returned it.
My favorite speakers, JBL 4311, have a simple dividing network with volume controls. 2 capacitors and Lpads. Yes, over time the Lpads need cleaning, but devoting a couple of hours every 10 years isn’t a big deal.
The drivers, cabinet, and crossover were designed to work together as is. The 3 drivers overlap in frequency response above 1500hz with no inductors choking them off. Additionally, the midrange driver is built with polarity reversed. This is a common technique JBL engineers used in various models.
These were the most popular studio monitors among recording engineers of all genres during the 1970s. They fell out of favor for mixing because they sounded too good and didn’t translate well to average consumer models, but many engineers used them at home for that very reason.
JBL engineers eventually succumbed to the marketing department and designed more complex crossovers in future models. They sound great but don’t have the dynamics of the 4311. It’s a unique and special speaker.
Why not, as long as you avoid making adjustments that are too high or too low, which could cause clipping, and the quality of the sound such as dynamics and microdetails remains unaffected. Especially during low-volume listening, it is desirable to apply EQ adjustments to compensate for highs and lows to achieve an equal loudness contour.
However, the questions that concern me are:
Will the quality of sound genuinely remain unaffected with EQ?
Should I opt for digital EQ (especially PEQ) or analog EQ?
"I have a 30K rig and use a $150 Schiit Loki Mini....why, Because I like to tweak bad recordings . Don't put it down until you actually try one."
I started with a Mini, it is now in the garage system. The middle one is in the HT. I finally got the Max in the main system - there is no going back now. I can fix a bad recording in seconds.
"@audiokinesis can you expand on how low, or how much of the phase curve that’s low inductance, at low impedance is acceptable for most tube gear?"
The interactions between the speakers’ impedance curves and the tube amps’ output impedances have too much variation for me to make a general recommendation of a specific minimum impedance value.
In general, a tube amp will put out LESS power (less wattage) into an impedance dip than a solid state amp; and MORE power (more wattage) into an impedance peak than a solid state amp will. So it’s not just the dips you have to be careful of; if there is an impedance peak in the crossover region (for example), you can end up with a frequency response peak in the same region when switching to a tube amp.
In fact when you read about someone trying a tube amp and it made their speakers sound worse, it’s very often because the interaction between the speaker’s roller-coaster impedance curve and the tube amp’s output impedance resulted in unwanted frequency response peaks and dips.
So I can’t really answer your question with specific numbers. The higher the tube amp’s output impedance, the more benefit from minimizing swings in the impedance curve and from keeping the average impedance fairly high.
Note in particular that the amp’s output impedance modifies the woofer’s effective electrical Q, raising it as if the speaker’s DC resistance was increased by the same amount. This has a greateer net effect on vented boxes than on sealed boxes. But it is also a potential "free lunch" that can extend the bass lower than it would have gone with a solid state amp, if the speaker was designed taking that higher output impedance into account.
Imo the thing to do is, use a modelling program that allows you to specify the amplifier’s output impedance, so you can get an idea of what the net result will be up and down the spectrum. It is possible to design speakers that work well with a wide range of amplifier output impedances, but woofer choices will be reduced, and you may need to make provisions for changing the port tuning frequency or for sealing up the port(s) completely.
@audiokinesis can you expand on how low, or how much of the phase curve that's low inductance, at low impedance is acceptable for most tube gear? I don't want to hijack the thread but isn't this the crux of amp/speaker "synergy" save perhaps efficiency? Also, every XO has a resistor value on at least one driver so the designer is making an "eq" choice for us (other parameters notwithstanding) whether we know it or not. Lots of speaker DIY sites will show final responses with different R values for the builder to mull over. Not all ears and rooms are equal.
How about single driver speakers sans any crossovers.
I think there is a purity and simplicity there that is another avenue to pursue.
Your hearing also has some inherent frequencies deficiencies especially as we get older. The pursuit of audio perfection is something you can chase your whole life. I guess that’s why it’s a hobby.
Some people are in it for the love of the equipment and that continued quest. Others are more in it for the enjoyment of the music. The constant upgrading can sometimes get in the way of enjoyment of the music.
I know I am guilty as charged.
As one who occasionally dabbles in crossover design, often with one eye on the frequency response curve and the other on the impedance curve, I’d like to toss out an observation:
Equalizing a frequency response anomaly without introducing an impedance curve anomaly often calls for twice as many crossover parts as equalizing the frequency response curve alone. The impedance curve is arguably of greater consequence when designing with tube amps in mind than when optimizing for solid state amps.
It would never occur to me to hand over my crossover parts count to my marketing department lest they attempt to ascribe virtue to the sheer number, but I got a chuckle out of something that happened at an audio show:
This guy came into the room and sighed as if he was finally hearing something relaxing, and said to me, "I can tell you’re using a very simple first-order crossover." He was close! There were actually twenty-seven elements in that crossover, but the acoustic rolloff WAS first-order for about 2/3 octave on either side of the crossover frequency.
vintage AR-2ax, two pairs of speakers, 3 way: two 8 ohm L pads each pair. Also renewed the AR-2ax crossover capacitors. Electrovoice crossover is components in a metal can full of tar. I’ve been advised by custom crossover makers to leave them alone.
then I use a microphone, ear level seated position, with tracks 9 to 28 from this GRP/Carver test tone CD
@carlsbad2Oh, I prefer a smooth and objectively neutral treble as well.
OTOH, Dali for instance, is making big strides by lifting up their treble response. I think there is a market for that, for hearing loss but also for low-level listening.
@erik_squiresI'm not saying you are misusing the term. I'm saying the term when it was coined last century was and is a bit of a misnomer.
My speaker manufacturer brags of a flat frequency response. Indeed. some very expensive speaker manufacturers tune their speakers to be bright because the target market who can afford expensive speakers tends to be older and have frequency loss in the higher frequencies.
I won't derail the thread by explaining why I, at 67, can still appreciate the flat response instead of the boosted treble.
I hope I'm positively contributing to your interesting thread.
The goal of a good crossover is a flat frequency response from bottom to top.
@carlsbad2I'm not sure all speaker designers share that flat goal. A speaker thatsounds good in a room and will sell may very well be their goal. The term speaker designers use in fitting different drivers together, and matching them to a cabinet is equalization.
The goal of a good crossover is a flat frequency response from bottom to top. This is the "equal" part of equalization. The term "equalizer" is actually a misnomer. it allows frequency response to be unequal to suit one's listening preferences.
@james633- That may be true. In most designs the raw sensitivity of the tweeters is higher than the woofers and/or the woofers need EQ to boost the bass by cutting the top of their response down, all of which forces us to lower the tweeter levels considerably.
The end result is a speaker which needs considerably more watts than it would otherwise, but we usually compensate for this with monster amps... so... 😂
@overthemoon- There are actually bad tone controls. Manufacturers would implement excellent analog stages and then glue on tone controls (or headphone amps) as after-thoughts. So, I can understand that there have been bad examples, there is also gear with consistently good examples. Luxman for instance makes excellent transparent tone controls (but not headphone amps).
@erik_squiresI appreciate your enthusiasm for tone controls. Early in my journey I appreciated the option to by-pass tone controls; why, I appreciate simplicity.
And in this journey personal preference makes a difference and its wonderful there are so many options.
I tend to think drivers that need a lot of smoothing through crossover parts get robbed of some of their sensitivity which results in heat build up and loss of dynamics. Good drivers are super important, far more important than fancy box materials and crossover parts (all things matter though).
As for target curves I am on board with Harman’s studies of about 5db in room slope from 200khz-20khz. That seems to work well in my room. Oddly I think Harman’s headphone curve is crap and far too bass heavy.
Sadly, those speaker level adjustments were often unreliable over time and the cause of much frustration.
Modern speakers are not designed for an anechoic chamber, but the measurements may be done that way in order to properly set crossover points and alignment. No competent speaker designer I know of would build a speaker for an anechoic chamber.
I do however agree that good tone controls in your preamp are wonderful. I’ve had gear with good and bad tone controls, so I can understand the reluctance of some listeners to use them again, but good ones exist!
No one's room and no recording or hearing is perfect. Let's be good to our enjoyment of music and use tone controls!
And those calculations/crossover designs are for the speaker when in a large padded cell.
'In the Beginning', speakers came with Level Controls, so they could be adjusted for your listening space, your preferences, your particular hearing including 'typical' age related, progressively reduced ability to hear highs.
'In the Beginning' Preamps/Receivers came with important features i.e. Stereo/Mono/l+r to r; l+r to l; phase; balance; low and high filters, tone controls. These days those controls can be 'in' or 'out', no reason not to have their potential benefit(s)
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