Tech Talk 2: The REASON why 2 tweeters wont work!

[@deanrantala]

I recently decided to re-purpose 2 old Bose SoundDock (powered) speakers for use on my computer. Each has a 1/8" Stereo Aux input jack and I initially wired the left output from my PC to BOTH (L+R) Input of the SoundDock on the left side, the the right output of the PC to both L+R speakers of the new "right side" sound dock. Notices some very drastic drop in high-frequency output. What I eventully ended up doing is building a small in-line RC filter that cuts all frequencies above 800Hz to the "outside" drivers of each Sound Dock. So the left speaker only reproduces high frequencies with the right-side driver and the right speaker only reproduces high frequencies with the left side driver. This 100% corrected the issue, and overall improved the entire response as I move my head around from side-to-side by the desk. The bass still comes through both drivers of both speakers and thus the bass response is great (for the size). Comb filtering is very real and impacts sound in huge ways.

[@dannyrichie9743]

Nice job.

[@Audiodreamer192-24]

I wish I found this channel a long time ago! It’s like fresh air! Detailed and so easy to understand. Awesome!✌️🔊🔊🔊🔊👍👍

[@11219tt]

Thanks so much for this content!!! Very interesting! Will definitely help me stop my room bette rams choose future speakers.

[@ratedAD]

This is excellent! I actually understand what you are saying. TY, dude!

[@sumeetlamba4603]

Brilliant. Thanks so much. This series is amazing. Very educational

[@Kareggan]

This was really great information. Thank you verry much. Is it possible that you do a test like this for Woofers and Midranges aswell? Have a great day.

[@dannyrichie9743]

We can, but as frequency decreases, they tend to couple rather than cancel each other out.

[@danashay]

Thanks again Danny. Brilliant.

[@manFromPeterborough]

I have a Foster 12" 3 way speaker with 2 tweeters in clover pattern above the mid driver, they are wired in parallel om one 2.2uF cap, I separated the 2 pos wires and put in another 2.2uF cap so each tweeter has own cap. the mid runs 6.8uF cap, woofer no Xover, these speakers are late 70's and were sold without brand name on the enclosure. My dad's first hifi had 8" Foster speakers with 2 different tweeters, a 65mm cone and 1' dome, the 65 tweeter ran 3.3uF cap and dome 2.2uF, The amp was Audio Reflex TK72. The 12" speakers were found on kerbside in 2008, Mum gave me the 8" speakers in 2005 when hard rubbish time came up in her area

[@edjackson4389]

My old Sansui SP2500s have stacked horn tweeters, and double mids tilted inward towards each other. but they have a zig zag shaped metal diffuser mounted over the top of them that works some kind of magic because they sound pretty good to me. When you remove the diffuser they sound horrible

[@shodan6401]

Danny, you spoil yourself with that MASSIVE computer monitor!

[@Silver_Surfer_1]

Got my answer on beaming with the Neo 8 watching your vid about selecting tweeters. Thanks.

[@tutnallman]

Gosh, how amazingly comprehensible. thanks

[@aaronschen9896]

Always wondered about this for the Dynaudio older confidence and evidence models. They use 2 tweeters right next to each other and a relatively complicated crossover (im told) to control vertical directivity. I can see how they get the destructive interference off axis as intended but not sure how they avoid the peaks at certain angles and frequencies. I know they are a technically competent company and the speakers seem to measure well off axis. One tweeter plays above 2.2kHz and one above 8kHz. Is 8kHz high enough to avoid comb filtering peaks at practical angles? New subscriber enjoying the content.

[@dannyrichie9743]

The higher the frequency the shorter the wavelength and the easier it is for them to be out of phase and cancel in the off axis.

[@shodan6401]

How do the Dali's measure, with the soft dome tweeter and the ribbon tweeter on top?

[@peterandersen4040]

Diff. frequence as the dome does not go high

[@TheZacharySutliff]

Very interesting. Thank you

[@iliascharis5668]

Dear sir does this phenomenon exist with the double woofers or double midrange or even double full range speakers?

[@dannyrichie9743]

It exists with any drivers as frequency increases. So at high frequencies the wavelengths are short and it will cause them to be out of phase and create a huge hole in the response. As wavelengths get longer the change is distance hardly effects them. So they couple and increase output.

[@musicstevecom2]

Danny Richie I always stack speaker in series having 2 speaker for Lt and Rt they sounded good. so is it better to disconnect the bottom tweeter so there's only one tweeter per side. I bought the RP-504 update kit and love them and I'm going to make them into towers any side effect to doing this? Vertical vs Horizontal or even stacking 2-together per side?

[@musicstevecom2]

I disconnected the bottom tweeter on the Rt and Lt (it bi-amp not to hard to do) It sound Terrible w just the top tweeter hooked up. Lol

[@dannyrichie9743]

And soon as you stack them up you will get the cancellation effects shown in this video.

[@mattmackay2973]

Do you work for NASA ?, You are the Man !!!!!!!!!.

[@faverodefavero]

A few questions, if you have time, please: What if the tweeters are exactly the very same and extremely well made and timed to perfection, let's say even hypothetically, would that negate any comb filtering effects? What are you thoughts on things like the BeoLab 90 with three firing tweeters on the same side? Could that be that case of such low tolerances that the tweeters play perfectly timed? I heard many speakers with side, up, or bsck firing "ambience tweeters" (not on the same side as the main front tweeters playing the very same frequencies as the front tweeters at the same time but firing in a different direction. I must say, in that case, I belive it sometimes does make the speakers sound more natural and "humanly better" (as far as my listening goes), not necessary, it doesn't bring more detail or anything to the played sound, just a small "upgrade" to the sound when done right. I belive in this case comb filtering would be negated or not noticeable, right? Since the frequencies arrive at different times to the ears and the tweeters are firing in different directions. An experiment I did was amplifying the top atmos drivers of some atmos stereo speakers to play the exact same thing as the front speakers at the same time (making it basically like a four speaker stereo system, two on each side, two firing to the top, two firing to the front). And to my ears it did sounded better (much better than using any DSP, Dolby, or Atmos filters / effects, and a little better and more natural and spacious than just playing the front speakers. Nothing major, just a little extra). I couldn't notice any comb filtering in such a case, which makes sense since the speakers are firing in different directions, so even though they are playing the very exact same thing it takes longer for the upfiring high frequencies to hit the ceiling and than reflect back to the ears, while the front tweeters reach the ears immediately. I would love for you experiment using good speakers that have atmos upfiring top drivers but playing them all in stereo like I did (top firing drivers playing the same thing as the front ones at the same time), I belive you will find it pleasing, again nothing major, just slight bit of extra spaciousness and sound "naturality ", really interesting. Thanks so much for you time and considerations. Appreciated.

[@Motoralbi]

I'm not him, but i think i can answer a thing or two: -having perfectly identical tweeters (in any aspect, like if they were clones) would not negate comb filtering, because this effect is caused by the fact that sound waves from two close tweeters will always arrive at a different time when you are off-axis (the signal coming from the closer tweeter takes less time to reach your ear, compared to the other): this causes the signals to cancel when the signals are out of phase, and since the wavelengths are in the ballpark of centimeters in the upper frequencies, slight distance changes easily produce out of phase situations at those frequencies. -i heard (maybe from danny himself? i don't remember) ambient tweeters don't cause comb filtering because the delay is too high in comparison to the front signal. I don't remember if it's our hears that perceive those as different signals (delayed) or a thing you can actually measure with a mic (for sure it can be seen in the impulse response). Edit: he wrote this thing in a comment right below (in response to rocifier)

[@Iam-mad]

The comb filter is a result of canccelation of 2 identical waves, when due to the time-difference in physical distance (mic 2" down) the identical waves have 180° phase turn, and cause then noise cancellation with each other. Meaning: as more identical the signals are, as better is the cancellation. Its like the noise cancellation headphones, same method.

[@audioprotaro1338]

best vid on this issue

[@paulpaulzadeh6172]

Great knowledge, great channel

[@johnpastuck352]

The theory behind a focused array is that two sources at equal distance from the listener will sum 3 db higher than the reflected sound. As Danny has demonstrated, the reflected response is always changing as the path lengths will be different. Thus the listener in the sweet spot will hear more of the recording and less of the room. See original Wilson WAMM, alothough I never heard Dave point this out.

[@davidketley5359]

Actually a 2" drop on the single unit gave an excellent response which from a more normal listening distance would equate to comfortable listening window? I had some Urie JBL 813B with the duel concentric drivers, does this solve the problem of integration

[@11219tt]

How does this issue work with two speakers placed left and right? Does the space inbetween each solve this problem since waves are so small?

[@dannyrichie9743]

Left nd right speakers do not receive the same signal (not mono), they are used in stereo.

[@kennetheis3588]

I understand and agree with your conclusions...but what about linear arrays of tweeters like many of the highest end speakers.

[@dannyrichie9743]

That's different. In that cause the line has to be long enough that you are in the nearfield. I did another video on that.

[@jeffhernandez5098]

Would this happen on the horizontal access? Thinking of a soundbar with LCR on the same horizontal access.

[@jeffhernandez5098]

axis, not access. sorry

[@anthonydicola6797]

Hello What's your thoughts on a company called Tekton? There speakers have anywhere from 2 to 5 or more tweeters!!! Thanks

[@dannyrichie9743]

We've upgraded several of their models. They definitely needed a lot of help, but their models with multiple tweeters don't have the issues that you see here. Only one of the tweeters is actually being used as a tweeter. The rest are being used as high mids like a filler driver.

[@bruceferrara3917]

Question...A friend has 4 B&W small bookshelf speakers that he insists on running all at once with a pair on each side about 24 inches apart...with pairs about 5 ft apart and listening position about 6 ft away. This can't be a good set up? Do not the multiple sound sources cause phase issues?

[@dannyrichie9743]

That set up will cause time arrival delays that will cause comb filtering (cancellation).

[@NotSure723]

Can this be alleviated by angling the tweeters outwards, away from each other, like on the old Studiocraft 330 speakers, for example?

[@dannyrichie9743]

Not really.

[@Inabottle]

whats a small amp I can use just for this, just looking for something compact and portable?

[@nyuszi36]

Now that I have learned this I wonder to myself how much of this effect is noticeable on stereo playback, where both channels play identical sound.

[@WateriZgood]

Would this still be an issue if I paired two tweeters but used a bandpass crossover on one of them? Example: A soft dome tweeter that plays 4k- 10K and then an aluminum dome to play 8K+???

[@stephenyoud6125]

kzbin.info/www/bejne/qJLdi6amn5yGZtE

[@endrizo]

well yeah but what about the line arrays like the infinity IRS V they have a tall array of 24 tweeters . time aligment must be a mess. and they are considered as one of the best speakers ever.

[@dannyrichie9743]

Line sources are very different. Watch this video to understand why a line source is different: kzbin.info/www/bejne/bZPahmh-lsyih9E

[@jeffkalina7727]

Does this explain why I found Tekton Double Impacts to sound wrong? By that I mean the sound changed with every small head position change I made from a sitting position? Curious as Tekton has many fanatical followers who don't perceive this. Your thoughts? Thank you.

[@thomasmleahy6218]

J.K. is that the manufacturer that has something like 6 to 9 or more tweets on their speakers? I thought that there had to be a reason why no other manufacturers were doing this. Forgot to mention last post- Thank you, Danny!!

[@Silver_Surfer_1]

Was wondering if this would apply to using two Neo 8 PDR planars? Was thinking of using 2 instead of 1. Is that a mistake?

[@dannyrichie9743]

One is already too long to use as a single tweeter. Two is way too long.

[@Silver_Surfer_1]

@@dannyrichie9743 Thanks for replying Dan. My original Neo 8's I used on top of a pair of 8" kevlar woofers totally open. (no baffle) Used as midrange and tweeter. Plenty of highs for me and sounded very large and airy (very open sounding). One of my better speaker builds. Hence the thought of using 2. But I see now that I should include a pure tweeter. MTM.....

[@iliascharis5668]

I would love at some point if you could measure the trio 15s from pureaudio project and draw your conclusions. Thank you in advance

[@dannyrichie9743]

I already know that is a disaster.

[@rocifier]

Does this still happen due to destructive interference with stereo or surround tweeters?

[@dannyrichie9743]

No, those get different signals and are too far apart. But then again room reflections do the same thing.

[@chadmorris946]

Worst offender has to be Axiom. I want to try some of their models but them passing off center channels with tweeters widely spaced on each end of the baffle just scares me away.

[@markusmathis1811]

How Infinity IRS 5 work? Like Tektron? Sorry for the question, i'm a beginner, seen a lot of Videos from PS Audio and Paul is in love with the Infinity

[@dannyrichie9743]

The Infinity model is a true line source. So the drivers act like one long line that is the same as a single driver of the same length. I think I did another video on that. The Tekton's actually only allow one tweeter to play as a tweeter (the one in the center). The ones around it are actually playing as upper mids.

[@thomasmleahy6218]

@@dannyrichie9743 Ahh, answers my query on other post.👍 Thanks Danny.

[@thomasmleahy6218]

Very interesting. What were those speakers that were very popular at the beginning issues of the absolute sound/ stereophile, where they were advocating 2 pairs placed one upside down on top of one another, just like your comb filtering example. Did anyone back then even notice the comb filtering? A person has to have trained ears to notice these effects, but once trained, they really stick out and are easily noticed. But being a person that doesn't believe in these effects, they also don't notice/hear the effects.

[@Poppinwheeeeellllllieeeeez]

Open baffle all the way mid tweeter mid config, powered sub support or h frame bliss .

[@zapdust2928]

can someone explain resonance frequency on tweeters since i've forgotten the exact meaning and don't know if "Very Low Resonance Frequency - 450Hz extended to above 40kHZ" means 450hz-40kHz i'm assuming it does but not so sure and idk if a tweeter going that low is realistic

[@zapdust2928]

@@badjonatan ok thanks man

[@seoulrydr]

Please oh please someone send this man a pair of Tektons....

[@carlosoliveira-rc2xt]

You obviously don't know how the Tekton tweeter array is implemented. The tweeters don't all play the same frequency range or the same intensity. Ditto for properly implemented multiple mids when handing off to tweeter. Come on guys this is basic shit that has been done for decades. No conspiracy here.

[@seoulrydr]

@@carlosoliveira-rc2xt There is what is said and there is what is measured. If there is a chance to see it, I'd like to see it for myself. You do you.

[@sovkiller]

That theory also has been refuted by another school, using the psychoacoustics, and with extensive double-blind testing, I'm not going into an argument here, just showing that every school has an opposed... Now me asking to get into more details, and not trying to argue, just trying to get more information...At intervals of 2"-3" it may be measurable, and more noticeable, but what about but at 6' or 10' away, can you get the same results measuring the effect? Now if you apply, lets say felt rings on one of the tweeters, will that affect that cancellation, or sum?... Or maybe if you use different tweeter types, horn vs dome, or different domes material, or paper vs dome, that will offer different freq curves and spectrums? What about then the ones who use "super tweeters", that are not even on the spectrum we can hear, and they still claim to listen the differences, and they will always overlap somehow..... The brain is a very complex machine, but unfortunately according to some other studies and articles, mainly in psychoacoustics, the human brain, will not pinpoint isolated frequencies, like these shown on your graph, or groups of so close frequencies like that. The brain works more like summing average machine inside; and for the lack of a better description, lets say: it uses like little "buckets" of freqs, and compensate for the differences. Otherwise, digital music will be unbearable with the steps on the squares waves....or maybe the class D amps, don't you think? See this video, and what do you think? kzbin.info/www/bejne/apOVeoKFna-grtk This is one of the most expensive systems in the world, custom-made, (even while I agree that expensive does not relate to quality in many cases) but this guy is dealing directly with Krell, and custom made even the room, what most of us can even think off...his speakers, has 30 tweeters on each speaker center, left and right, and 10 in the back of each...120 ribbon tweeters, and 7" Scan Speak Kevlar drivers...the subwoofers inside the wall, now is that guy nuts? Combing does not apply here? Also, as a side note, I have a very decent customized headphones setup, indeed I can put together 3 of them, one portable, two desktops...and own some of the best available headphones, and all my amps are custom-made, not cut corners, RK40 black velvets, audio caps, all class A, etc, etc, etc...and the best part, a gift from a friend, so this is not no pissing contest expenditure here... Now while listening both, side by side, I can't see how the combing effect impacts the speakers, as the sound is amazing either way.... Not saying that in other cases it may be more detrimental, but in mine, thanks God, I can't hear it... And I bet someone that does here...!!!!

[@jameshockensmith1119]

Tape some laser pointers on your mic and your get it closer to center

[@dannyrichie9743]

It doesn't matter. We don't fix our ears to a specific height. The comb filtering still causes holes in the vertical off axis response and it will make the room response unbalanced.

[@davidmorgen4558]

Did some one say bose?

[@sveneisenhauer1]

Danny, shouldn’t this video be labeled Tech Talk 3, not 2? Just stumbled across this trying to find #3, but then saw you you had two TT’s labeled with No. 2.

[@scotthullinger4684]

I never met a tweeter which didn't work. If they don't work, then they've been abused, or destroyed, or they were defective to begin with -

[@shodan6401]

Hmmmm.... Feb. 28th - about two and a half weeks before the COVID hits...

[@JF-ut9qu]

How do designers create line sources with dozens of tweeters get around this problem, especially of the electrostatic variety?

[@mikafoxx2717]

He addressed this in another video, but the tweeters have to be a minimum distance to each other for the wavelengths used and they end up beaming vertically due to a huge effective length of the tweeter, meaning you only ever hear one tweeter at a time that you're in line with. The horizontal dispersion is still good because it has a small wavelength in width so it doesn't start to beam until very high frequency in that direction.

[@carlosoliveira-rc2xt]

At a listening distance of say 12' the comb filtering should be minimized and with closer spacing of the tweeter as well.

[@dannyrichie9743]

Not at all. We don't just hear the response that is on axis. We hear a combination of on axis, horizontal off axis, vertical off axis, and all of the reflections of the room. So an uneven vertical response can cause an uneven room response and an unbalanced sound.

[@scottlowell493]

Despite all the hype, I listened to the twin-tweeter models of the AXIOM audio speakers. Underwhelming to say the least. Not just the twin tweeters, but the blah upper midrange.

[@dannyrichie9743]

I've measured and tested three of their models. I can't disagree.

[@scottlowell493]

@@dannyrichie9743 I'm glad you did some mythbusting. I purchased some ADS-l710 from a guy 2 years ago. He had a pair of Axiom M-80's and wanted my impression. I said that the upper mids sound like they have been dropped back, and the speaker is out of balance. I'm a little vague on the imaging too. IMO, the reviews were not accurate.

[@friedmule5403]

But what / why then the line source? It contains 12 Neo3. :-)

[@GlueFactoryBJJ]

No to two? Then how about companies that use THREE tweeters (Miller and Kriessel)? That's got to be THREE times better, right?

[@sudd3660]

three is actually usable, now you can have one of them to the highest frequency only. and the other two act more like upper midranges.

[@GlueFactoryBJJ]

@@sudd3660 That's not how the M&K tweeters work. All three are set for the same frequency range...

[@sudd3660]

@@GlueFactoryBJJ ok, then thats how they do it.

[@GlueFactoryBJJ]

@@sudd3660 I guess I want clear in my OP. What I meant was would the three tweeters over come the inherent phase shift problems that are audibly apparent off axis? I understand how they (the (modern) M&K speakers are constructed, but I don't have the $$$ to see how they sound and no local dealer. It's more of a conceptual question, like at what point does the number of tweeters begin to behave like a line array?

[@sudd3660]

@@GlueFactoryBJJ line array effect start immediately if they close enough center to center, but the nice flat response is limited to the physical size of the line aray, that is 3 tweeters high in this case.

[@johnsnow9887]

all it's called wave interference

[@JodyM2]

Oh No should I throw away my M&K S150 LCR's 3 Tweeters a piece?

[@nabildanial00]

Explain how Tekton Design can make it work, with 15 tweeters per side no less lol.

[@seoulrydr]

I hit send before I saw this... my bad!

[@dandinhofer9240]

Where dies this guy get his information from????!!??? Stacked speakers are CONSIDERED AWESOME BY LEGIONS! Stick to your bar graphs and I'll enjoy my little 😂 unorthodox rig ....

[@dannyrichie9743]

The measurements don't lie. Stacking speakers is a comb filtering disaster.

[@kevonmanuel]

Danny Richie (GR-Research) vs Eric Alexander (Tekton Design) - Multi tweeter hater vs the Multi Tweet lover - $49.99 Pay Per View main event.

[@carlosoliveira-rc2xt]

You're totally off in your understanding of the tweeter array. This is what happens when a viewer comments on something he knows nothing about.

[@kevonmanuel]

@@carlosoliveira-rc2xt Don't assume I don't know about the tweeter array partner. I know that Tekton is not using a bunch of tweeter to play the same signal. Eric is using the array to couple the low mass tweeters to play the mid-range which he can crossover to the woofer at a lower X-over point. A single tweeter is used to the High frequencies. It's people like yourself who cannot see sarcasm in a post. They (you) think that you so ultra knowledgable about things and you must correct to internet.

[@scottlowell493]

@@carlosoliveira-rc2xt He stated the truth...he did not qualify a position, just two opposed POV's.

[@carlosoliveira-rc2xt]

@@scottlowell493Let me explain. Richie is not a multi tweeter hater. Many of his designs have multiple tweeters. This video is not a video about not using multiple tweeters but on using them incorrectly. This is what I mean regarding he not knowing what he's talking about since in reality they're both "pro multi tweeter". His attempt at humour fails since its inaccurate. If he actually knew what he's talking about he would have seen this.

[@IliyaOsnovikov]

@@kevonmanuel Have you seen top Denny's line array designs? They could have more tweeters than any of Tekton models.

[@tommyK7282]

Sorry but this doesn't prove anything when it comes to the human ear and how it perceives two tweeters or multiple of any drivers.....

[@dannyrichie9743]

No, it actually shows exactly what we hear.