Midtop Clash FR Data
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URL: https://forum.speakerplans.com/forum_posts.asp?TID=11586
Printed Date: 27 March 2026 at 11:10am
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Topic: Midtop Clash FR Data
Posted By: Rog
Subject: Midtop Clash FR Data
Date Posted: 02 September 2007 at 6:31pm
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Cabs on test were.
Boke MA912 with P Audio SN 12B & B&C DE 250. The 12" horn had no rear chamber cover fitted but the driver did have a sealed rear chamber because of the cabinet. I called this cab Boke MA912 Adam.
Boke MA912 wth P audio C12 300 MB and P Audio WM 44 (I think). The 12" horn had the correct rear chamber cover. I called this cab Boke MA912 Florian.
MT 121 with P audio SN 12 MB and P Audio BMD 750. This is basically one horn from the MT 122 design and a BMD 750 on P audio horn above it. I don't know which P Audio horn was used. I called this MT 121.
MX12 with P Audio SN 12 B and P audio BMD 750. This is a horn designed by Mykey and is available from the Jan Audio website. The measurements were taken without any rear chamber cover, but should not make much diffrence to the data above 300Hz. In fact the lack of a rear chamber means no reflected sound can re-emerge though the cone and add colouration, so it acted like a dipole. The response below 300Hz would have been effected by having no rear chamber cover fitted. The data for the HF section would be the same if the rear chamber cover was fitted or not.
Porn Horn V2 with P Audio SN 12 B and P Audio SN 740. The HF horn was designed for the Beyma CP 755 Nd. The SN 740 seemed to keep up with the 12" horn in level but not in terms of sound quality were the Beyma is a lot better. The CP 755 Nd's measurements would have been a lot better too, especially the distortion tests.
Measuring equipment used was a Bruel & Kjaer 4939 mic, which has a response from 4Hz to 100KHz and a M Audio Preamp. Sampling rate was 24 BIT 48KHz as no design had any output above 22KHz. The measurment program used was Ease. This sends out a test signal and then records the result. The recording is then used to deduct over 50 measurment types. The test signal use was swept pink noise from low to high. The range was 7Hz to 24KHz, but I stated the plots from 20Hz as there is nothing present that low, apart from wind noise.
The measurments were taken in a slightly diffrent way. I did this as I wanted to see what would happen if an average DIYer got hold of some cabs and drivers and throw it all together. Instead of measuring the LF and HF sections seperately, I measured the combined output of the whole cab. Again this was done to see what the whole cabinet including crossover settings from a LMS would be like. 2.83v, or 1 watt was applied to the 12" driver and the HF horns output was then set to be level wth the 12" horn. There was no HP filter set on the 12" driver for measurments, it was applied when doing the listening tests. For most of the cabs the 1" drivers were crossed over at 2.2KHz with a 24dB Butterworth slope on the HP filter. 1.5 and 2" drivers used a 1.7KHz HP filter with 24dB Butterworth slope. The LP filter on the 12" drivers was mostly 2.2 KHz 24dB when used with a 1" HF and 1.7KHz 24dB when used with either a 1.5 or 2" HF. But what we did was to set up each cab to give the best response we could. It meant that most of the time the above settings were used, but for some cabs the 12" drivers LP filters slope and type was adjusted to give the flattest response. Delays between HF and LF sections were also adjusted to give the flatest response. There would have been no point in using the same settings for each cab as the different components used dictated different settings. All we wanted to know was how good you could make 2 components put togther in a cabinet sound and perform.
First off is the frequency responses. The lower limit on the plot is 20Hz the upper is 30KHz. The accuracy of the sensitivity is within +/- 0.1dB. All easurments were taken at 1 meter.
 This is for Adams MA912. You can see that the 12" horn only goes to 800Hz. The phase plug in this design does nothing. You can also see a lot of SPL below 100Hz, this is due to the high winds were experinenced earlier in the day.
 This is Florians MA912. Again the 12" horn goes nowhere near high enough to match with the 1" driver.
 This is an overlay on the 2 MA912 cabs. You can see that the B&C DE250 goes a lot higher than the P Audio 1" driver. Also note that the P Audio SN 12B plays lower and higher than the C12 300MB.
 This is the plot for the MT 121. There is lots below 400Hz and it plays higher than the Boke MA912's, so fills the gap a bit better. The HF is a 2" unit and you can see the limited response above 12KHz.
 This overlay of the MA912 and MT 121 shows the better output below 400 Hz and the better midrange response.
 This is the plot for the MX12. Don't pay any attention below 300Hz. But its worth noting that this horn doesn't like the BMD 750 driver, as the response is very weak around 6 to 10KHz.
 Overlay of MX12 and MT 121
 Plot of the Porn Horn V2. This is the only design in the group that uses a phase plug on the 12" horn and you can see the diffrence it makes.
 Adams MA912 against the Porn Horn V2.
 MT 121 against Porn Horn V2. Note that the MT 121 has the same output below 400Hz.
 MX12 against Porn Horn V2.
 An overlay of 4 cabinets. I didn't put Florians plot on here as the response was not as good as Adams MA912.
I will post all the THD and harmonic distortion plots, group delay and water fall plots later in another post.
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Replies:
Posted By: Rog
Date Posted: 02 September 2007 at 7:15pm
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My concusions were that the Porn Horn V2 is around 3 to 4dB more efficient than its nearest competitor and as it can handle a lot more power with its bigger compression driver can play a lot louder. We didn't take maximum SPL readings but it was very obvoius that the Porn Horn was louder. In fact you could stand around 3 to 5 meters away from all the other designs and alomst talk to each other when playing flat out, but with the porn horn 10 meters out was on the point of pain and we decided to listen from 15 meters where it was still so loud you could not talk to each other. The B&C DE 250 sounded very nice on the Boke MA912 horn. The P Audio 1" driver didn't sound as good or have the HF extension. The trouble with the MA912 was that its phase plug did nothing and only extended to around 800Hz. This left a gap between the 12" and 1" and theres nothing that could be done to get a flat response. I could have taken the crossover point of the 1" driver down to below 1KHZ, but this is not a good idea if you want to keep the driver working for more than a few mins. The MT 121's 12" horn would have nearly kept up with the porn horns if it had a phase plug. You can see its response below 400Hz is good, but it drops below this. Theres still more output around 1KHz though with the MT 121 12" horn and with its lower 1.7KHz crossover point the 12" horn nearly met the 2" driver. I quite liked the sound of the MT 121, but its poor HF extension was evident and made it sound a bit flat. Distortion was also high with the P audio 2" driver. The MT 121 was also quite loud, but I think you would need 2 to keep up with 1 porn horn v2. I also liked the sound of the MX12. It would have be nice to have had the rear chamber cover to give the low end a bit more extension. The HF driver didn't like the MX12's horn, but the dip in response around 6 to 10KHz kind of smoothed out the sound and it was quite easy on the ear.
So from best to worst here is my list.
Porn horn for quality, everyone said it sounded like a Hi Fi and for max output. Maybe not the cheapest build but I think less would do more and also give you better reliability too.
Boke MA912 Adams. I liked the HF on this cab. The mid was a bit lacking but the lovley top made up for it. Max output was ok but not as good as the MT 121. Dispersion was very tight in the horizontal plane and this cab would array quite well.
MT 121. Good output from the 12" horn, nice smooth sound and good punch. The HF lacked fidelity and extension. More output than the MA912, but its poor HF perfromance puts it below Adams MA912.
Floirans MA912 had a better midrange sound than Adams, but the HF was not so good. Output was simular to Adams MA912.
MX12. Mid sounded very good but I didn't like the HF. I think there is a great cab just wating to happen here. I would love to hear one with a better HF, maybe the SN 750 or even better the CP750 Nd. Would have also been nice to have the rear chamber cover next time.
So what would I choice.
For me the whole event reconfirmed one thing and thats that home built DIY cabs can't compeate with anything comercial. I know that if I had brought any pro midtop that there would have been a massive difference in sound quality and output from the DIY designs. The porn horn also showed this up for me too. While the porn horn is not a comercail design, that fact that it has had a lot of R&D meant that nothing in the group came even close in my opinion. I know I would say that, but if you were there I think you would of had to have said the same thing. Also using chinese amps and the berry crossover was very limiting. It got so bad that I had to swap to a digidrive just to get the test done. The bery was just too inflexable, slow and kept droping out when changing either crossover points or EQ. This made it impossible to use for the real time RTA we were doing. I also managed to distroy 2 of the X1 drivers withing mins of arriving with my test tracks. These are tracks I know most pro equipmet can survive and it was just another thing that proved to me that DIY is a masive compromise.
So I could use the porn horns if I had too. The MT 121 is an ok choice if you are good at building. The MA912 is ok if you don't expect too much output and maybe reliablity. The MX12 with the right drivers is a good choice too as its an easy build and dosen't cost too much. I think by the time you have fitted an HF driver worth having in an MT 121 and also taken into account the time it takes to build one it offers the worse price to perfromance ratio.
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Posted By: norty303
Date Posted: 02 September 2007 at 10:14pm
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One question i wanted to ask was about the change to the recommended drivers for the MT122. When the spec changed to P-audio, was there a lot of difference between the sound quality, particularly the high end extension of the Beyma P800ti and PD123ER combination? ------------- My laser stuff: http://www.facebook.com/SubsonicSystems" rel="nofollow - Frikkin Lasers |
Posted By: super-hero
Date Posted: 02 September 2007 at 10:29pm
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Hi Rog, your coments about the cabs are really interesting.
You say that a diy build cannot compete with commercially available cabs. But as you know, a lot of us go for the diy cabs because of cost and the satisfaction of building.
What commercially available cabs, new or old, would you rate as the best mid high.
Also do you have a spare copy of your test cd
 Oh, and also, when you were testing the cabs, did you apply any eq to them.
Cheers Percy. ------------- I'm not an animal, I'm a human being. |
Posted By: tb_mike
Date Posted: 02 September 2007 at 10:37pm
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Interesting to see how the 12"s reach up to the compression drivers,good one! Its always good to see good measurements AND subjective thoughts aswell to make sense of things. The critical midrange 300hz - 3khz also looks like the most troublesome area,right in the crossover range,and where the phaseplugs make the most difference. Wonder how these units compare with 6/8" midrange eg XTRO/TMS style. Liking the skeletal enclosure. What 18"s were in the X1s? |
Posted By: Heathrow_B_line
Date Posted: 02 September 2007 at 11:36pm
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thanks for making time to attend Rog! you are the man! ------------- Produce a killer sound. Take no prisoners. |
Posted By: Heathrow_B_line
Date Posted: 02 September 2007 at 11:58pm
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also Rog is there any chance of overlaying my porn horn with the p audio hf comp driver and shonky sealed bowl to one you have tested... i just think it would be quite interesting to note the differences ------------- Produce a killer sound. Take no prisoners. |
Posted By: Rog
Date Posted: 03 September 2007 at 12:03am
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No, I'm a horrible little sh*t that knows f**k all. Drivers in the X1 were P Audio C18 650EL. Yes norty, if you spend more it gets better. Everyone felt that this weekend, but won't say it. PD 123ER and Beyma costs more and sounds much better. Can't believe it took this long for people to know this. Look at the plots and listen to the reports. More expensive = better. Always. So who's going to own up and say they want to own some sh*t then. Buy the bokes, they're the best. 16 porn horn mk 1 owners can't be wrong right. If I tell you it cost £20 do you want it. Ha ha, told you this a long time ago Mykey. You belivin it yet. You know why you left. Nothin changes. |
Posted By: LostGrayCat
Date Posted: 03 September 2007 at 5:09am
| Define "sh*t". |
Posted By: mykey
Date Posted: 03 September 2007 at 5:24am
Rog! I didn't design the MX12 and the 2'' horn is a B&C
everybody has seen the link to the drawing, its available for everyone.
If any of my designs were there! I would have been there too like you were
congrats anyway my friend, and kick some butt at the show mate. ------------- ......just all them hanging there like giant bananas. |
Posted By: adambomb
Date Posted: 03 September 2007 at 11:13am
| Great report Rog, honest and accurate. |
Posted By: adambomb
Date Posted: 03 September 2007 at 11:14am
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Also.. there was no EQ (that I was aware of) applied to the cabs.. that's as they are with a flat EQ.... so some holes could be filled.
Also learnt alot from Rog on this... set the dealays and polarites first.. it makes such a huge difference to the FR! I need more time to play.
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Posted By: norty303
Date Posted: 03 September 2007 at 5:28pm
I'm curious why the plans were changed to the P-audio's then, with no mention of the Beyma/PD combo now, not even as an alternative option. As any designer would want their cab to sound the best, why remove the best option? Was this linked with a P-audio distribution deal or something to do with PAP sponsorship of the site?
Wish i coulda brought my combo down to compare directly ------------- My laser stuff: http://www.facebook.com/SubsonicSystems" rel="nofollow - Frikkin Lasers |
Yes norty, if you spend more it gets better. Everyone felt that this weekend, but won't say it. PD 123ER and Beyma costs more and sounds much better. Can't believe it took this long for people to know this.Posted By: josh
Date Posted: 03 September 2007 at 8:06pm
| when you say the mt121 lacked extension do you mean the HF didnt play high enough, or that it didnt play low enough....or did you mean the mid horn didnt play high enough to meet the HF?? |
Posted By: adambomb
Date Posted: 03 September 2007 at 8:20pm
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The P.Audio comp was used as it was the only driver Rog had to hand at short notice... was not planned like this. |
Posted By: Heathrow_B_line
Date Posted: 05 September 2007 at 12:47am
the high freq response dropped off rapidly. in terms of the lower limit it almost matched the porn horns output which surprised me.
its a shame we didnt have time to test it with the correct sn12b instead of the sn12mb that was in there
 maybe one for the future clash ------------- Produce a killer sound. Take no prisoners. |
Posted By: Tekasis
Date Posted: 06 September 2007 at 3:05pm
So would using a Beyma 2'' comp instead of the P.Audio one made that much of a noticable difference ?
What combo is that Norty ?
Is it the fact that the SN12B is more powerful than the SN12MB why you'd expect better results or is there other reasons ?
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Posted By: norty303
Date Posted: 06 September 2007 at 4:49pm
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Well the 800 is well respected as a 2" comp driver and is one of the ones people seem to speak about when they talk of spending proper money on a top end, and seeing the results. given that it's nearly 3 times the cost of the P-audio it really should be better, which is why i questioned why it had been removed as one of the recommended drivers, why not simply add the P-audio's as the cheaper option as well
Ive got PD123ER's with Beyma 550's and a pair of Fane slots for the sparkle. Obviously not so good at range, but they sound nicely detailed to my ears at mid ranges. ------------- My laser stuff: http://www.facebook.com/SubsonicSystems" rel="nofollow - Frikkin Lasers |
Posted By: mylesound
Date Posted: 14 December 2007 at 4:14am
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i know im kinda late but do you think the HF roll off in the mt 121 can be solved with some EQing or would that put too much strain on the driver?
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Posted By: josh
Date Posted: 14 December 2007 at 3:05pm
| So if the better p audio option arent the best drivers for the mt122 plan then what are? |
Posted By: levyte357
Date Posted: 20 November 2009 at 12:35am
Sorry to wake this up again peeps, but few questions for the eq masters... To attempt to flattening this out with Ultradrive param eq I'm guessing, 1. +8db, approx Q factor=3 @ 1.1khz 2. +3db approx Q factor=2 @ 1.5khz 3. +6db approx Q factor=2.5 @1.8khz? Qfactor might be well out, cant be bothered switching on DCX 2496  @Adambomb, please feel free to correct above guesses... ------------- "Who am I? I'm the guy who does his job.. You must be the other guy". |
Posted By: adambomb
Date Posted: 20 November 2009 at 1:48am
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Do the delays before you move to the eq... This made a big difference (I know I delayed the comp - but I could not tell you by how much)...
Also, the plot above is with the first settings off the top of my head - no eq and xo at 2.2khz I think, no delay. Try bringing the comp down to 1.8khz (the DE250 was fine at this as it's on a pretty long horn in the ma912). E.Q wise, again I did it with a laptop, easera and ecm8000... Took me all day, I'll fire up the deq and get the info for you, but to get it flat took quite a few nudges (tried to bias to turning things down rather than up). ------------- http://www.freespeakerplans.com" rel="nofollow - www.freespeakerplans.com |
Posted By: adambomb
Date Posted: 20 November 2009 at 1:49am
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Once I had the eq right I noticed the difference mainly on vocals.. Much warmer and smoother. ------------- http://www.freespeakerplans.com" rel="nofollow - www.freespeakerplans.com |
Posted By: levyte357
Date Posted: 20 November 2009 at 11:14am
Thanks for that.
Can see lowering x/o to 1.8-2K would achieve much already.
I have an ECM8000 somewhere, and mate has 8024, and this do the analysis and auto delay/eq, or is there free s/w to do this?
Obviously settings will be stored in ultradrive, once acquired.
Cheers. ------------- "Who am I? I'm the guy who does his job.. You must be the other guy". |
Posted By: darkmatter
Date Posted: 20 November 2009 at 8:20pm
| re. software - Room EQ Wizard |
Posted By: JaKe
Date Posted: 21 November 2009 at 12:02pm
| Try removing the "fudge bungs". |
Posted By: adambomb
Date Posted: 22 November 2009 at 12:54pm
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+1 always wanted to try that but never got round to it. ------------- http://www.freespeakerplans.com" rel="nofollow - www.freespeakerplans.com |
Posted By: levyte357
Date Posted: 22 November 2009 at 1:25pm
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Thanks for the replies chaps, but got let down by seller. He said cabs were loaded with DE250s, but they where actually loaded with the cheap Paudio '44 nonsense. So I'll have to settle for unmodified MT121s instead.  ------------- "Who am I? I'm the guy who does his job.. You must be the other guy". |
Posted By: adambomb
Date Posted: 23 November 2009 at 2:29pm
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That wasn't Trebor was it? as they were defo DE250s when they left me.
------------- http://www.freespeakerplans.com" rel="nofollow - www.freespeakerplans.com |
Posted By: levyte357
Date Posted: 23 November 2009 at 2:40pm
Nope, someone else... Probably better off now anyway, as I'm using ME60 horns, and can attach whichever comps I choose, within reason. ------------- "Who am I? I'm the guy who does his job.. You must be the other guy". |
Posted By: Ryan94
Date Posted: 06 May 2013 at 5:46pm
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Sorry to bring up such an old thread, Ive just bought a pair of the Boke MA912s of Trebor which adambomb used to own, just having a play about with them and was wondering if anyone new what delays where needed for them. |
Posted By: Ryan94
Date Posted: 13 May 2013 at 5:22pm
| Anyone? Got them out Friday and would like to have them set up properly. |
Posted By: Henner242
Date Posted: 06 January 2014 at 11:03pm
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Ryan mate you got boy'd!! ------------- make cabs not war |