• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required. There are many reviews of audio hardware and expert members to help answer your questions. Click here to have your audio equipment measured for free!

Revel M106 Bookshelf Speaker Review

JustIntonation

Senior Member
Joined
Jun 20, 2018
Messages
480
Likes
293
I actually think speaker designers think about this a lot, and is why a dip at the crossover around 2-3 kHz off-axis isn't terrible, as in many rooms it won't be very audible.
I stronly disagree with this. I think it's very audible. It's exactly the thing that has bothered me for so many years and last year I dove in deep and tested this extensively and confirmed this was exactly the thing that bothered me with most speakers.
I modelled it also with computer sims and ran audio through it. I may still have some of those audio files online and posts about it on this forum, I can look them up later if you want.
To me, there isn't a worse place to place a crossover than between 2-5kHz (and actually slightly below that still too as a crossover will have a bit stronger effect above the crossover point when not fully at the cancellation axis yet). To me, errors there make the treble untransparant and harsh. Perhaps this is another reason why people often prefer a sloped response as it will warm up and hide such errors a bit.
Btw, crossovers aren't the only thing to blame here, diffraction effects can be bad as well in this area.

edit: btw, you can do this test yourself easily as well, a simplified crossover test.
Set up a Linkwitz Riley lowpass on one stereo channel in your daw and a Linkwitz Riley highpass on another stereo channel in your daw. You can make a Linkwitz riley filter slope by simply combining two 6dB or 12dB or 18dB etc lowpass or highpass filters (for instance with Fabfilter ProQ) set at the same frequency (usually with Q=1 though it depends on the EQ used, it'll work with Fabfilter ProQ) and set the EQ to natural/minimum phase.
Then combine the two channels again. The result should be a 100% flat frequency response with group delay shifted according to the filters. (if you're making a 12dB/oct LR or 36dB/oct LR this way then phase reverse one of the channels for the flat result)
Then simply put a delay on either the highpass channel or on the lowpass channel to simulate vertical off-axis. Calculate the delay needed for which off-axis degree based on wavelength of your crossover fr, where half wavelength = the cancellation axis.
Then simply run audio through it and listen to the results. Hear the bad effect of a crossover at for instance 3kHz.
And you can take the modelling further too, you can EQ in the off-axis response of your mid-driver (also in natural/minimum phase) for the particular off-axis you're simulating and hear how this affects the crossover.
Btw, you can also do all of this visually by running an analyser on the results, or as I found out only recently the easy and free modelling program VituixCAD will model the above all correctly too and gives nice visuals (though you can't hear the results with that program ofcourse).
 
Last edited:

BYRTT

Addicted to Fun and Learning
Forum Donor
Joined
Nov 2, 2018
Messages
956
Likes
2,452
Location
Denmark (Jutland)
.....it will be with Bliesma T34A-4 tweeter (which has the off-axis response that is better than most 1" tweeters) crossed at 1300Hz with very close spaced SB Acoustics SB15CAC30-4 mid driver (CTC spacing is half wavelength of the crossover freq), and Seas L26ROY XM001-04 woofer (closed), on a wide baffle with 10" diameter roundovers. It should indeed put all two-way bookshelf speakers to shame :) Finally building it now, will share buildplans once finished.
Sounds really great i love that wide baffle and 10inch roundover plan :)...

Below animation is pure spacing simulation for 132mm @1300Hz LR2/4/8/16, pure for spacing in that used drivers directivity are a homebrew model that is perfect omni 20Hz-20kHz so that we get to see in isolation what vertical spacing is doing and thats why spinorama plot looks so borring because all curves is mostly laying upon each other, horizontal plots are ommited because they simply perfect and XO in example is of linear phase.
JustIntonation_1000mS.gif
 

JustIntonation

Senior Member
Joined
Jun 20, 2018
Messages
480
Likes
293
Sounds really great i love that wide baffle and 10inch roundover plan :)...

Below animation is pure spacing simulation for 132mm @1300Hz LR2/4/8/16, pure for spacing in that used drivers directivity are a homebrew model that is perfect omni 20Hz-20kHz so that we get to see in isolation what vertical spacing is doing and thats why spinorama plot looks so borring because all curves is mostly laying upon each other, horizontal plots are ommited because they simply perfect and XO in example is of linear phase.
View attachment 71228
Nice, thank you :) Yes I've made those sims too. I'll likely use LR6 crossover. In minimum phase but this doesn't matter at all for the fr effects in the graphs you made.

Btw, developing it for DIY build too. The 10" diameter roundover will be made with a 10" (25cm) PVC pipe of 6.1mm thick with a few tricks to cut it easily (PVC pipe will not make the inner enclosure, that will be a normal rectangular box and the PVC pipe halves will 'slide' over it partly).
 
Last edited:

CDMC

Major Contributor
Forum Donor
Joined
Sep 4, 2019
Messages
1,172
Likes
2,321

Newman

Major Contributor
Joined
Jan 6, 2017
Messages
3,449
Likes
4,209
Nice spin
 

Xyrium

Addicted to Fun and Learning
Forum Donor
Joined
Aug 3, 2018
Messages
574
Likes
493
Nice, thank you :) Yes I've made those sims too. I'll likely use LR6 crossover. In minimum phase but this doesn't matter at all for the fr effects in the graphs you made.

Btw, developing it for DIY build too. The 10" diameter roundover will be made with a 10" (25cm) PVC pipe of 6.1mm thick with a few tricks to cut it easily (PVC pipe will not make the inner enclosure, that will be a normal rectangular box and the PVC pipe halves will 'slide' over it partly).

Not that this isn't too far off topic already, but your build reminds me of the Linkwitz design, with all of this mention of PVC pipes and that Seas woofer. :)
 

pozz

Слава Україні
Forum Donor
Editor
Joined
May 21, 2019
Messages
4,036
Likes
6,825
I can remember (but I’m not completely sure) an interview with ME Geithain founder, Mr. Joachim Kiesler, that he is not a fan of waveguide systems because of their unnatural soundstage and short time reflections within the waveguide.
Some historical speakers of them seem to have had small “waveguides“, but their current line up is avoiding them completely.

ME Geithain has very high reputation in the pro business. In many German forums user often state that with ME Geithain their search for the right speaker was over.
I once heard a big system of theirs at High End Munich and I can follow such statements.

Unfortunately, their prices are quite high.
Do you mind looking for the interview?
 

Chromatischism

Major Contributor
Forum Donor
Joined
Jun 5, 2020
Messages
4,765
Likes
3,703
I stronly disagree with this. I think it's very audible. It's exactly the thing that has bothered me for so many years and last year I dove in deep and tested this extensively and confirmed this was exactly the thing that bothered me with most speakers.
I modelled it also with computer sims and ran audio through it. I may still have some of those audio files online and posts about it on this forum, I can look them up later if you want.
To me, there isn't a worse place to place a crossover than between 2-5kHz (and actually slightly below that still too as a crossover will have a bit stronger effect above the crossover point when not fully at the cancellation axis yet). To me, errors there make the treble untransparant and harsh. Perhaps this is another reason why people often prefer a sloped response as it will warm up and hide such errors a bit.
Btw, crossovers aren't the only thing to blame here, diffraction effects can be bad as well in this area.

edit: btw, you can do this test yourself easily as well, a simplified crossover test.
Set up a Linkwitz Riley lowpass on one stereo channel in your daw and a Linkwitz Riley highpass on another stereo channel in your daw. You can make a Linkwitz riley filter slope by simply combining two 6dB or 12dB or 18dB etc lowpass or highpass filters (for instance with Fabfilter ProQ) set at the same frequency (usually with Q=1 though it depends on the EQ used, it'll work with Fabfilter ProQ) and set the EQ to natural/minimum phase.
Then combine the two channels again. The result should be a 100% flat frequency response with group delay shifted according to the filters. (if you're making a 12dB/oct LR or 36dB/oct LR this way then phase reverse one of the channels for the flat result)
Then simply put a delay on either the highpass channel or on the lowpass channel to simulate vertical off-axis. Calculate the delay needed for which off-axis degree based on wavelength of your crossover fr, where half wavelength = the cancellation axis.
Then simply run audio through it and listen to the results. Hear the bad effect of a crossover at for instance 3kHz.
And you can take the modelling further too, you can EQ in the off-axis response of your mid-driver (also in natural/minimum phase) for the particular off-axis you're simulating and hear how this affects the crossover.
Btw, you can also do all of this visually by running an analyser on the results, or as I found out only recently the easy and free modelling program VituixCAD will model the above all correctly too and gives nice visuals (though you can't hear the results with that program ofcourse).
Easy to model, but does this manifest at the seat of the listener at 3 meters in a small room? Let's find out. But first, I am in no way doubting your experience.

See here for detailed measurements, including the "floor bounce" early reflection at 2500 Hz. There is a smaller dip in the horizontal axis which I would expect to hear. Does this show up in the in-room response, at your seat? Let's see:

S400 Pair In-Room 1-6 Smoothing.png


Well, it looks like it can't be picked out from the rest of the ups and downs created by the room. Is the little dip at 2600 Hz our culprit? Or is that acoustical interference from the room? We can't really tell from here. Either way, we certainly aren't registering a huge dip at our seat once all of the direct and reflected sound is combined. So I would argue that on this particular speaker, it may be only barely audible. This is a carpeted room so that may be helping. Walls are bare painted drywall, no treatments.
 

JustIntonation

Senior Member
Joined
Jun 20, 2018
Messages
480
Likes
293
Easy to model, but does this manifest at the seat of the listener at 3 meters in a small room? Let's find out. But first, I am in no way doubting your experience.

See here for detailed measurements, including the "floor bounce" early reflection at 2500 Hz. There is a smaller dip in the horizontal axis which I would expect to hear. Does this show up in the in-room response, at your seat? Let's see:

View attachment 71272

Well, it looks like it can't be picked out from the rest of the ups and downs created by the room. Is the little dip at 2600 Hz our culprit? Or is that acoustical interference from the room? We can't really tell from here. Either way, we certainly aren't registering a huge dip at our seat once all of the direct and reflected sound is combined. So I would argue that on this particular speaker, it may be only barely audible. This is a carpeted room so that may be helping. Walls are bare painted drywall, no treatments.
I would be the first to say that actual in room measurements do say a great deal. Though 1/6 octave smoothing is too much smoothing in my opinion. The most smoothing one can do would be psychoacoustic smoothing I think, otherwise stick to 1/12 or 1/24 octave.
But a mic in a room and a static graph do not say how our ear hears. There's the direct sound which hits the ear from a different angle than reflections and therefore the direct sound gets quite a different head related transfer function equalized sound than a reflection from the ceiling, floor, back wall and even side walls. On top of that modes and reverb / longer reflections arrive at a different point in time and this can psychoacoustically matter. So what your mic pics up is not the same as what your ear pics up.
Having said that, I've never heard great sound in a small room. Tried it myself once with quite a bit of treatment but couldn't get there back then (early days, was naive in many ways so not best attempt ever). Don't know if what I wrote earlier applies to a small room, quite likely other things matter more.
 

KaiserSoze

Addicted to Fun and Learning
Joined
Jun 8, 2020
Messages
699
Likes
592
I'll be using the Hypex Fusion plate amps in my design so I'm not limited by the natural Fs in my design as the Fusion amps have built in DSP I'll be using a Linkwitz transform to lower the -3dB point. My design is primarily for a nearfield / midfield monitor, it will provide enough SPL for me even after the Linkwitz transform.
With this in mind I think the new XM001-04 L26ROY is just about the perfect woofer for closed appication. What is important in the woofer is the SD and the xmax ofcourse but also especially how linear the motor force is under excursion (so how clean it stays under excursion). The new L26ROY excells in this. It will really give clean bass up till right about its limit also under Linkwitz transform in a closed box.
I have the woofers here already and tested them and they are amazing, truly clean and deep and in control. Had looked into other woofers before that but they dissapointed.
Btw here are Klippel test results of the new L26ROY: https://audioxpress.com/article/test-bench-the-l26roy-10-subwoofer-from-seas They are truly good.
Also the L26ROY is not just a sub, it can be used as a woofer as it stays clean enough and doesn't have fr problems >100Hz or too high a inductance (which modulates with excursion) like many subwoofers. I plan on crossing mine at about 180Hz still soubting between LR4 or LR6 (will determine final crossover freq and steepness from testing).
If the driver you're looking for is for sub duties only then many more drivers become available, but for my application I don't think there are many other options which are as good as the new L26ROY.

About the T34A-4, the way he got the off-axis so amazingly good is by the geometry of the tweeter, it is extremely curved / round. Though I think the real magic was how can such a large tweeter behave so well up to 20kHz, this was achieved by making it very light and unequal thickness across the membrane this is really a tweeter from the future :) It is a bit expensive (I paid about €265 per tweeter inc shipping) but indeed as you say not crazy for the things it does (I think it's even cheap for that actually haha).
Btw, don't mind Dickason's measurements of the T34A-4 he did them badly I think under not good circumstances and his measurements show that, Troels and Hificompass made much more clean measurements.
I also have already tested the tweeters myself and they sound jaw dropping amazing :) The transparancy and dynamics are the best I've personally heard and that was only on a test baffle yet which still had diffraction.
One other thing which is not often looked at in speaker design is that our ears are so much more sensitive between 2-5kHz and I've found that any crossover effects in this range sound the worst, they make for harsh sounds and destroy transparancy for me and just totally mess up the whole smoothness and balance of the treble to me. With the T34A-4 one can cross low enough that all crossover effect are not just very far off-axis but also stay below 2kHz. Our ears have a sensitivity dip between 1-2kHz and I've tested the effects of this and the crossover dip is just so much less noticeable between 1-2kHz and doesn't make the treble sound bad (I find it mostly makes things sound a bit further away which isn't that bad a thing). In my personal view of things the treble "sits" on the very important 2-3kHz range, I personally call that the lower trebble. I make sure that part is completely flat and smooth also off-axis. Completely unaffected by the crossover or mid-driver dropoff or by diffraction. I have heard the effect of this only in simulations on the computer (where I run audio through it and listen with headphones to the sim), to hear it for real I have to finish my speakers :)

Edit: oh btw, about intermodulation distortion. Since there are almost no measurements of this one must go by the standard HD measurements. There are two general rules here. If the driver has a rise in its fr this will also amplify IMD products, and one can deduce IMD amount by the relation between the 2nd harmonic and 3rd and 5th harmonics. It is especially important that the 3rd and 5th harmonics are very low. not so much for the 2nd harmonic. So the T34A-4 may not look to be too impressive with its 2nd harmonic level, but that is inaudible in reality what's important is that its 3rd and 5th harmonics are the lowest there are, and that it's cone breakup / rise is above the audible range.
And for the mid driver this is where it most often goes wrong. Most mid drivers will have levels of 3rd and 5th harmonic which are not particularly low and rising a bit till the crossover point and then they often have a beakup mode or rise close to 5kHz. Even though you cross the driver below 5kHz this does not matter at all for the HD and IMD products falling around 5kHz they get amplified all the same. The SB15CAC30-4 is simply amazing in this, it has extremely low 3rd and 5th harmonic, and a small drop in sensitivity around 2-5kHz no rise at all. The result is the cleanest mid driver I've ever heard, also extremely linear. On a wide baffle where the baffle step occurs below where you cross the mid driver it can go plenty loud too / plenty of dynamic range. I think it's a steal for the price when used this way :) I'm so happy with it. (for a higher more normal crossover point it's perhaps not the best, it has a bit of a dip at around 2.6kHz in the off-axis for instance, etc. but that's all not a problem when crossing it at 1.3kHz with the T34A-4)
Btw, the SB15CAC30-4 has it's main cone breakup / rise in the 9-10kHz range. This is where we find another dip in the ears sensitivity / equal loudness curve, and it's far enough away from the crossover point so that hardly any distortion product fall on that anyway so this is really the most perfect metal mid-driver there is in my opinion :) It's like it's psychoacoustically perfectly made for the human ear.

It is apparent that you are cooking up something very special there. I am most certainly envious. When I looked at the distortion curves for the T34A-4 my thoughts were the same as yours, but I did notice that H3 started to climb at about 1.5 kHz, however H2, H3, H4 and H5 all remain low enough for the tweeter to sound clean even if crossed over at around 500 Hz, where it would probably give a good directivity match directly to a woofer. It seems weird that it could work that way, but depending on the diameter of a woofer, somewhere around 500 Hz where wavelength is appreciably greater than the diameter of the woofer the dispersion of a woofer is about as good as it is for a tweeter. Not exactly of course but close, which says that the real reason for the directivity mismatch between a typical woofer and a typical tweeter is that the tweeter can't play low enough to interface to the woofer before the woofer becomes very directional.

Anyway, you obviously are cooking up something very special, and it is going to be interesting to see how it spins. Although I can't imagine that you'd be done with it before the end of summer.
 

KaiserSoze

Addicted to Fun and Learning
Joined
Jun 8, 2020
Messages
699
Likes
592
Sounds really great i love that wide baffle and 10inch roundover plan :)...

Below animation is pure spacing simulation for 132mm @1300Hz LR2/4/8/16, pure for spacing in that used drivers directivity are a homebrew model that is perfect omni 20Hz-20kHz so that we get to see in isolation what vertical spacing is doing and thats why spinorama plot looks so borring because all curves is mostly laying upon each other, horizontal plots are ommited because they simply perfect and XO in example is of linear phase.
View attachment 71228

Excellent visual there. It is very apparent that so far as smoothness in the polar response vertical axis is concerned steeper slopes are better. No question about that, and it is probably the best argument I know of for steeper slopes. Still you end up with those two holes and the only thing you can do short of going with concentric is to keep the vertical spacing as short as possible so that the nulls will occur at +/- big angle as opposed to +/- smaller angle. I've decided that I like concentric, but Amir has urged AJ to stop messing around with concentric drivers.
 

JustIntonation

Senior Member
Joined
Jun 20, 2018
Messages
480
Likes
293
It is apparent that you are cooking up something very special there. I am most certainly envious. When I looked at the distortion curves for the T34A-4 my thoughts were the same as yours, but I did notice that H3 started to climb at about 1.5 kHz, however H2, H3, H4 and H5 all remain low enough for the tweeter to sound clean even if crossed over at around 500 Hz, where it would probably give a good directivity match directly to a woofer. It seems weird that it could work that way, but depending on the diameter of a woofer, somewhere around 500 Hz where wavelength is appreciably greater than the diameter of the woofer the dispersion of a woofer is about as good as it is for a tweeter. Not exactly of course but close, which says that the real reason for the directivity mismatch between a typical woofer and a typical tweeter is that the tweeter can't play low enough to interface to the woofer before the woofer becomes very directional.

Anyway, you obviously are cooking up something very special, and it is going to be interesting to see how it spins. Although I can't imagine that you'd be done with it before the end of summer.
Thanks :) Will keep you posted! It won't be crazy expensive to build yourself too, less than 3000 euro for a pair incuding everything (amps wood drivers taxes shipping paint glue screws damping material etc etc).

As for the T34A-4 crossover point. The HD shown at https://hificompass.com/en/speakers/measurements/bliesma/bliesma-t34a-4 is relative to the SPL produced at the voltage driving the tweeter. So you must look at for instance 2v83 in the 'axial magnitude frequency response' graph to see which amplitude the tweeter produces at which frequency at that voltage. I wouldn't take it down to 500Hz as you will need quite a high voltage down there to reach for instance 90dB (which would give 96dB at the crossover point) and if you then look at the 'HD frequency response' graph you'll see quite high HD which also indicates quite high IMD which will be audible.
For a 1300Hz crossover the H3 is already rising as you say, but it will be 6dB down at 1300Hz from the Linkwitz-Riley crossover so it will be fine there (especially with a dedicated NCore amp in the Fusion plate).

I'll see how fast I get finished, I do hope in less than 3 months :) I already have the drivers, amps and PVC tubes. Will order pre-cut wood this week and start building the thing :) Will start a new thread here on ASR for my build soon.
 

Newman

Major Contributor
Joined
Jan 6, 2017
Messages
3,449
Likes
4,209
....One other thing which is not often looked at in speaker design is that our ears are so much more sensitive between 2-5kHz and I've found that any crossover effects in this range sound the worst, they make for harsh sounds and destroy transparancy for me and just totally mess up the whole smoothness and balance of the treble to me..... Our ears have a sensitivity dip between 1-2kHz and I've tested the effects of this and the crossover dip is just so much less noticeable between 1-2kHz and doesn't make the treble sound bad ....
I think it's very audible. It's exactly the thing that has bothered me for so many years and last year I dove in deep and tested this extensively and confirmed this was exactly the thing that bothered me with most speakers.
I modelled it also with computer sims and ran audio through it. I may still have some of those audio files online and posts about it on this forum, I can look them up later if you want.
To me, there isn't a worse place to place a crossover than between 2-5kHz (and actually slightly below that still too as a crossover will have a bit stronger effect above the crossover point when not fully at the cancellation axis yet). To me, errors there make the treble untransparant and harsh. Perhaps this is another reason why people often prefer a sloped response as it will warm up and hide such errors a bit.
I agree about the 2-5 kHz range but not the 1-2 kHz range. AFAICT the 1-2 kHz range is just as sensitive to artefacts, probably more so. This is backed up by the general understanding of the sensitivity of the ear.

So, 1-2 kHz might be the only worse place to put a crossover than 2-5 kHz. :) You probably need that XO point around 500 Hz or less. Good luck!

cheers
 

KaiserSoze

Addicted to Fun and Learning
Joined
Jun 8, 2020
Messages
699
Likes
592
Nice, thank you :) Yes I've made those sims too. I'll likely use LR6 crossover. In minimum phase but this doesn't matter at all for the fr effects in the graphs you made.

Btw, developing it for DIY build too. The 10" diameter roundover will be made with a 10" (25cm) PVC pipe of 6.1mm thick with a few tricks to cut it easily (PVC pipe will not make the inner enclosure, that will be a normal rectangular box and the PVC pipe halves will 'slide' over it partly).

According to Siegfried the corner round-over begins to be effective for wavelengths where 1/8 the wavelength matches the radius of the round-over. I recall this because a couple weeks ago it came up here with mod a member had made to Sony SS-CS5 and I couldn't recall what Mr. L had written exactly so I went and looked at it again. With radius 5", it will start to be effective at 40" wavelength => 338 Hz and will be increasingly effective as frequency goes higher. Which means that if the baffle is as wide as it apparently will be, the round-off will be effective by the point where frequency reaches the strong 1st peak in the diffraction ripple.
 

JustIntonation

Senior Member
Joined
Jun 20, 2018
Messages
480
Likes
293
I agree about the 2-5 kHz range but not the 1-2 kHz range. AFAICT the 1-2 kHz range is just as sensitive to artefacts, probably more so. This is backed up by the general understanding of the sensitivity of the ear.

So, 1-2 kHz might be the only worse place to put a crossover than 2-5 kHz. :) You probably need that XO point around 500 Hz or less. Good luck!

cheers
I don't see why 1-2kHz would be worse? Look at the equal loudness curve. There's a dip in our ears sensitivity between 1-2kHz.
And I've also tested the exact effect of crossovers on fr with simulations and actual audio. It is quite apparent that crossover between 1-2kHz is way less objectionable than the crossover between 2-5kHz. And I've shared my audio sims with various music with various people and they all agreed. Would also stand up to any blind test without any problems it's quite apparent.
You can do a very simple test of this yourself. Simply put a notch filter on your audio and put it at 1.3kHz and A/B with and without it. And put it at 3kHz and A/B with and without it. And then A/B between the notch at 1.3kHz and 3kHz. No comparison, 1.3kHz will sound way less objectionable.
Make sure you make the notch about the right width / Q though to model for instance a LR4 cancellation axis.
 

JustIntonation

Senior Member
Joined
Jun 20, 2018
Messages
480
Likes
293
According to Siegfried the corner round-over begins to be effective for wavelengths where 1/8 the wavelength matches the radius of the round-over. I recall this because a couple weeks ago it came up here with mod a member had made to Sony SS-CS5 and I couldn't recall what Mr. L had written exactly so I went and looked at it again. With radius 5", it will start to be effective at 40" wavelength => 338 Hz and will be increasingly effective as frequency goes higher. Which means that if the baffle is as wide as it apparently will be, the round-off will be effective by the point where frequency reaches the strong 1st peak in the diffraction ripple.
Yes, that's the idea :) The baffle will be 29cm wide + the 12.5cm of the roundover on each side so in total 54cm wide. It will indeed reduce the first peak which sits on the top of the baffle step (though not completely eliminate it, it will be very smooth and insignificant, and pretty much no diffraction above that at all).
 

KaiserSoze

Addicted to Fun and Learning
Joined
Jun 8, 2020
Messages
699
Likes
592
Thanks :) Will keep you posted! It won't be crazy expensive to build yourself too, less than 3000 euro for a pair incuding everything (amps wood drivers taxes shipping paint glue screws damping material etc etc).

As for the T34A-4 crossover point. The HD shown at https://hificompass.com/en/speakers/measurements/bliesma/bliesma-t34a-4 is relative to the SPL produced at the voltage driving the tweeter. So you must look at for instance 2v83 in the 'axial magnitude frequency response' graph to see which amplitude the tweeter produces at which frequency at that voltage. I wouldn't take it down to 500Hz as you will need quite a high voltage down there to reach for instance 90dB (which would give 96dB at the crossover point) and if you then look at the 'HD frequency response' graph you'll see quite high HD which also indicates quite high IMD which will be audible.
For a 1300Hz crossover the H3 is already rising as you say, but it will be 6dB down at 1300Hz from the Linkwitz-Riley crossover so it will be fine there (especially with a dedicated NCore amp in the Fusion plate).

I'll see how fast I get finished, I do hope in less than 3 months :) I already have the drivers, amps and PVC tubes. Will order pre-cut wood this week and start building the thing :) Will start a new thread here on ASR for my build soon.

I did notice all of that and also that when you select the higher voltages on the little buttons the distortion doesn't increase too much. Also, since the graph shows dB relative to the fundamental (doesn't it?) the dB numbers should have the same significance irrespective of frequency. Or so it seems to me. But I'm uncertain because he does not show the fundamental. I'll have to ponder this a while.
 

BYRTT

Addicted to Fun and Learning
Forum Donor
Joined
Nov 2, 2018
Messages
956
Likes
2,452
Location
Denmark (Jutland)
Excellent visual there. It is very apparent that so far as smoothness in the polar response vertical axis is concerned steeper slopes are better. No question about that, and it is probably the best argument I know of for steeper slopes. Still you end up with those two holes and the only thing you can do short of going with concentric is to keep the vertical spacing as short as possible so that the nulls will occur at +/- big angle as opposed to +/- smaller angle. I've decided that I like concentric, but Amir has urged AJ to stop messing around with concentric drivers.
Agree :) myself bought some KEF Q150 couple of months ago to canabalize the driver array for diy fun and lol i haven't yet had time and energy to listen how they sound stock, for me its okay Amir try stop AJ relative in relation to what he heard in his sessions so far for coxials ;) but pretty sure myself can get that Q150 array combined some woofer and unlimited DSP engine at 192kHz to perform over avarage or maybe more.
 

JustIntonation

Senior Member
Joined
Jun 20, 2018
Messages
480
Likes
293
I did notice all of that and also that when you select the higher voltages on the little buttons the distortion doesn't increase too much. Also, since the graph shows dB relative to the fundamental (doesn't it?) the dB numbers should have the same significance irrespective of frequency. Or so it seems to me. But I'm uncertain because he does not show the fundamental. I'll have to ponder this a while.
Nope that's not how it works. You see the HD generated by the frequency in the graph. And the level (SPL) of that particular frequency you see in the 'axial magnitude frequency response graph'.
So for instance if you select 5v6 in the 'axial magnitude frequency response graph' you'll see that that voltage gives 102dB SPL at 2kHz, but only 91dB SPL at 500Hz. Then you look at the 'HD frequency response (315 mm distance)' graph and select 5v6 there and you'll see the HD generated at which frequency. But it means that if you look at the HD generated at 500Hz you're looking at the HD generated by 500Hz at 91dB SPL, and if you're looking at 2kHz in the same graph still at 5v6 you're looking at the HD generated by 2kHz at 102dB.
edit: in other words, the 'axial magnitude frequency response graph' is the fundamental for the 'HD frequency response (315 mm distance)' graph.
edit2: and if you see in the 'HD frequency response (315 mm distance)' for instance H2 at 500Hz at 5v6 at -44dB that means that this H2 product will actuall fall on 1kHz (500Hz * 2) with an amplitude of 91dB - 44dB = 47dB SPL.
 
Last edited:

Andreas007

Active Member
Joined
Mar 11, 2019
Messages
137
Likes
353
Location
Germany, Bavaria
I see that you don't have a lot of humor man. German perhaps?
Yes, I’m German. Are your stereotype believes now satisfied?
Maybe you can also help me what was so humorous about your first post? I’m eager to learn humor. Ha, ha! Or should it be three times? Germans don’t know... Ha, ha, ha!
 
Top Bottom