Ultimate midrange shootout - evaluation of impedance graphs

Find the data here:
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This video is a collaboration between people all over the world, thank you to them for making this happen:
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www.bladeice.com/
audiostatus.lt/
hepaking.com

[@nonsuch]

To get rid of the impedance rise in any driver, I always create a simple 2 component "Zobel Network" which is basically an impedance equalization that consists of a resistor and a capacitor in series placed parallel between the terminals of the speaker to counteract(flaten) the rising impedance. The rise is caused by the inductive reactance of the voice coil. It's easy to calculate but there are plenty online Zobel / Impedance Equalization network calculators.

[@PeterMMMMM]

Amazing explanations. Extremely usefull data for builders. You are a gem!

[@NackDSP]

Great work here. Very few look interesting to me. Linearity is king for me. So only three green. To get that, requires piston like behavior with no cone flex. That eliminates all those light weight, high sensitivity Fostex style drivers. I want a Qts below 0.8 or so. This indicates a good strong motor that can move the weight around. After that I want a large Xmax to give a good SPL at the low frequency end of the response, and low harmonic distortion. It is possible to systematically judge the linearity by plotting the theoretical impedance response from the TS parameters and then subtracting the theoretical impedance response from the measured response. The difference is all the small bumps caused by harmonics. It would be fun to see a Bielsma 3" dome in the comparison.

[@vincenttrottier6053]

Isn't the point of a midrange to let an other driver handle the low end? You can then have a bunch of detail in the midrange (with low distortion), the most audible frequencies. So I don't see the point of looking for large X-max. There is a lot of bad info out there on this subject. Qts characterises the dampening of the driver in an open baffle setting. Qts=1 has the quickest stopping time possible (critical damping). Qts ranging from 0.7 to 1 is concidered optimal for damping a resonant system. Qts=0.1 for example, will resonate a long time after you stop the music or tap it. Qts=1 stops the quickest after you tap it, this implies that a Qts above 1 is pointless. The box you use will add damping to the driver (raise Qts). For a midrange I think a good desing method is to make a scealed box large enought to not affect the driver too much. But you can put a 0.5 driver in a small box to raise it to 0.75. This method has the disadvantage of causing compression, limiting X-max, discortion, coupling with the box resonances... Same principle for ported boxes. So it's not really about the motor is what I meant to say hehe...

[@disienna]

Looking at your data, that ScanSpeak looks like a very nice driver. I mean there are a few others of course, but it doesn’t seem like you show much love for it. The Low Qts makes it nice for a small enclosure. I bet the specs that come with the driver would give you all that you need to know. They are a great company building TOTL drivers for ages as I’m sure you know. Anyway, great into again! I’m loving this series. Just seeing this many drivers side-by-side is enlightening. All things are some sort of compromise.

[@tomsettles6873]

Great job! Much appreciated. I'm going to build a pair of 3 way speakers with 8" or 10" woofers and will use your results to purchase the midranges.

[@kewlbug]

I appreciate these. I have more fun tuning, so I don't always look at speaker performance enough.

[@sadclown304]

You did a great job sir. And I liked the explanation, quite detailed and easy to understand as always

[@666nacirema666]

I just got these neat little 75mm drivers. Pretty high qts but very very smooth between 180 and 3000 hz. Printing a temp baffle for them and my tweeters and gonna mess around with them in the car this weekend

[@salientram]

Incredible precise and detailed video.

[@kartesian5737]

Thanks for this review. Just some information about the one you name « Crouton ». It isn’t a midrange but a wide band dedicated to pro audio ultra compact line array. We usually produce it in 32 or 64Ohms but the distributed version is 8Ohms for DIYers using it in compact home cinema, 2 units in parallel in each satellite. The brand name Kartesian is linked with the French mathematician Mr R Descartes who set up the 1st scientist method to improve the understanding of any physical topic.

[@RAW-CAt]

I do apologise for this "pun" with the name, It will be addressed and corrected in the future video, no bad intent, just having fun. And I will make sure to address the intended use case for this particular driver. Thank you for clearing that up👍

[@kartesian5737]

@@RAW-CAt Do not apologise, it’s OK.

[@Mark_5150]

A lot of the Le graphs show why you should run these drivers in a 3-way setup, crossovers will keep most of the wiggles out, which is what people should notice in their tuning sweeps.

[@squirtmph]

Crossover vs SPL Regarding (3) way In highest. Audio Which way it's the best regarding only on sound quality ? Thanks allot 🎉

[@Mrhifitunes]

Drivers with a polevent at the back can not be placed on a solid surface for impedance measurements but should be raised so the venthole is free to breath

[@RAW-CAt]

All drivers were measured in free air, holding in hand, not on a surface👍 The video is just a demonstration of the principle.

[@disienna]

Brilliant work! Very much appreciated. I can’t wait to download these particularly after you do the FR. Hopefully you’ll do off axis as well. Thank you again

[@shawnbrennan7075]

Well done sir

[@vincenttrottier6053]

Hey great vid, can't wait to see the rest. Personaly when it comes to midranges I prioritise detail. Therfore id be interested to compare mms to find something low. I also want the driver to shut up quickly so qts=0.7 to 0.9 is best. Ideally we could take a look a spectral decay charts to compare the clean ranges of the drivers and chart them. Max Spl (taking the power into account) could also be interesting to many ppl. Keep up the good work!

[@ZZPxFTW]

I wonder if the Scanspeak 10F would perform better in a sealed dash enclosure or pillar pod with its low Q... very interesting.

[@solow970]

I just ordered the d4s wide bands specs were good and reviews were good too. Fingers crossed

[@chriscuthbertson]

Do you have a part number for them?

[@RAW-CAt]

I might have them coming for this test🙃 Need to wait a couple of weeks.

[@eliseoquiroz8321]

I wonder how T/S and impedance changes after drivers are installed in their final state? Measuring the wires at the amplifier outputs

[@chrishuyler3580]

Really curious to see how the Fostex plays out over the remainder of your tests. They are a hidden gem in the home audio world, and many will modify them further (coating cone, etc).

[@napatencie4421]

What about Rms (mechanical resistance) and details of sound with low levels?

[@RAW-CAt]

What do you mean about details of sound on low levels? Rms is something that needs to be measured with added mass or an enclosure. Not gonna do that.

[@neilziesmer6109]

WHAT IS YOUR FAVORITE CLEANEST 100 ISH WATTS X 4 CHANNEL AMP FOR A PILLAR MID AND TWEET USE ?

[@RAW-CAt]

IMO 100W is way too much. 30-50W is plenty enough. I have Alpine F409 and F305 that are super clean.

[@danielgarcia3452]

Exelente video. Quisiera preguntarte que valor de resistencia usas para hacer las mediciones.? Gracias de ante mano

[@RAW-CAt]

I believe it's a 47ohm resistor.

[@seanbrown8269]

It's possible the Chinese driver is good. Time will tell, but remember that a huge majority of drivers are manufactured in China and there is no reason one of those oem manufacturers couldn't sell a clone of one at lower cost directly.