within +/-4db for 5 octaves……..widely available from a manufacturer producing drivers for over 40 years…….
My vote goes for the Seas L22RN4X/P H1208.
My hero Albert Von Schweikert (R.I.P) chose it among many tested, and he was a geinus in designing speakers inc xovers, and he used them in the upgrade for the VR-4 to VR 5-7.
Owned a upgraded pair for 20 years, and it uses 2 pieses H1208 per side in about 37 liter each reflex, and loved them
I also use the fantastic Mundorf ATM29 by the way, from 1850 hz.
Here is old and newer version of the H1208, it´s quite different..
I blow 4 of them a 5-6 hour long wiskey-night, when the 5,6 ohm resistor say "god by", and the xover was glued like hell.
Albert used 3 coils for the filter.
(vart bor du i Sverige Theo ?)
Regards John
Attachments
My suggestion is the Eighteen Sound 8 MNB 420 (16 Ohm) https://www.eighteensound.it/en/products/lf-driver/8-0/16/8nmb420
in 10 liters sealed with a Qtc around 0.77 (vary with available box volume) . A single driver Sim below... One driver holds 101 dB at 1 meter with 250 watts and 5.8 mm cone movement. Sd = 225 square cm.
With your amps and DSP you can easily Eq to cover the 40Hz to 300Hz band.
The have a superb low Mms (17g) to Bl (12) ratio of 1.41 with a fabric round so they have a super clean low distortion upper bass / low midrange performance ie the opposite of heavy coned/weak motor/rubber surround drivers in ported boxes with muddy male vocals and low end piano.
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No need to worry about any SPL, Xmax or Eq / power handling issues with 6 of these per side... 6 drivers have an Sd of 1,350 square cm which is more than than a single 18 inch driver.
I have done a Sim and increased VAS and driver diameter appropriately showing the six drivers (each still in under 10 litres and same 0.77 Q) with the same 250 watts power. The 6 drivers will hold (continuous, not just peaks!) 111dB at one meter... !
A pair of speakers (twelve 8 inch drivers in total) will hold 114 dB at 50Hz.... And thats before any boundary reinforcement and line array throw advantage over point source (a single 18 inch driver).
Plus they can do this with just +/_ 2.75 mm cone movement... This is vital as the less a cone(s) have to move the less they distort.
I have done a Sim and increased VAS and driver diameter appropriately showing the six drivers (each still in under 10 litres and same 0.77 Q) with the same 250 watts power. The 6 drivers will hold (continuous, not just peaks!) 111dB at one meter... !
A pair of speakers (twelve 8 inch drivers in total) will hold 114 dB at 50Hz.... And thats before any boundary reinforcement and line array throw advantage over point source (a single 18 inch driver).
Plus they can do this with just +/_ 2.75 mm cone movement... This is vital as the less a cone(s) have to move the less they distort.
Look´s like a real good driver, but maby 5,8 mm xmax will be a problem at 40 hz if you lso need headroom.
How connect 4 x 8 inch woofers with 16 ohm version ?
2 x 2 in paralell and the other 2 x 2 , and paralell to 4 ohm at the filter?
Regards John
As per my Sim with the six drivers Xmax is not an issue... One speaker (six eight inch drivers) holds 106 dB at 40 Hz, a pair of speakers (twelve 6 inch drivers) holds 109 dB at 40 Hz and this figures are before any room gain/boundary reinforcement which will typically be around 4 dB... All these figures are with just 2.75 mm cone movement.... Less than 50% of the drivers XMax... Size matters! 😉 🤣
TheoSweden,
Overall I think its a great design / project and will sound awesome with a wide range of good drivers.
The one slight "theoretical" issue (which I have no experience of) but I only mention so you can account for it when measuring / voicing / Eq'ing is the difference in "SPL throw" between point source (your MTM mid/high are a point source) and your bass/low midrange which will act like a line array.
A point source reduces by 6 dB per doubling of distance.
A line array source reduces by 3 dB per doubling of distance.
For example:
Assume your point source measures mid/high frequency drivers have a measured SPL of 100 dB at 1 meter, they measure 94 dB at two meters, 88 dB at 4 meters and just 82 dB at 8 meters.
Now assume you adjust your bass/low midrange drivers and amps/levels/crossovers to get the same 100 dB SPL measured at 1 meter... At 2 meters they will measure 97 dB, at 4 meters 94 dB and 91 dB at 8 meters... An 11 dB mis match!!
Of course this does not allow for reflections/room gain etc which usually reduces the effect a fair bit, but its at its worst in open air live sound where there are no walls and the bigger the room the worse the issue gets.
If you measure and "voice" the system at your listening position you will be ok, but just have to live with a less accurate sound as you move closer to the speakers.
Hope this helps and good luck, I will be really keen to hear if you have an issue in your room with your system.
All the best
A.
Overall I think its a great design / project and will sound awesome with a wide range of good drivers.
The one slight "theoretical" issue (which I have no experience of) but I only mention so you can account for it when measuring / voicing / Eq'ing is the difference in "SPL throw" between point source (your MTM mid/high are a point source) and your bass/low midrange which will act like a line array.
A point source reduces by 6 dB per doubling of distance.
A line array source reduces by 3 dB per doubling of distance.
For example:
Assume your point source measures mid/high frequency drivers have a measured SPL of 100 dB at 1 meter, they measure 94 dB at two meters, 88 dB at 4 meters and just 82 dB at 8 meters.
Now assume you adjust your bass/low midrange drivers and amps/levels/crossovers to get the same 100 dB SPL measured at 1 meter... At 2 meters they will measure 97 dB, at 4 meters 94 dB and 91 dB at 8 meters... An 11 dB mis match!!
Of course this does not allow for reflections/room gain etc which usually reduces the effect a fair bit, but its at its worst in open air live sound where there are no walls and the bigger the room the worse the issue gets.
If you measure and "voice" the system at your listening position you will be ok, but just have to live with a less accurate sound as you move closer to the speakers.
Hope this helps and good luck, I will be really keen to hear if you have an issue in your room with your system.
All the best
A.
As per my posts.... Used in singles Xmax is a factor... Used in multiples it is not... I cant explain it any simpler than that... Its crystal clear in the Sims I posted... 2.75mm cone travel at 40Hz at high SPL... There is no issue.
yeah, with 6 x 8" woofers per side, there is so much Sd to the system that other problems seem to go away. He does not need a lot of Xmax, and he does not need a lot of individual driver efficiency either.
Almost any decent 8" woofer would show dramatically good results. 6 drivers will have 7.8 dB increase in efficiency over a single, and a 15.5 dB increase in total SPL capability relative to a single. The voltage sensitivity increase will depend on how they are wired up: 2 parallel set of 3 in series (+6 dB), or 3 parallel sets of 2 in series (+9.5 dB).
Tjena!
That driver is probably really nice! Now it feels like I want a more sensitive one.
I have no hurry so time to think about it and I might change my mind. I talk more about the cabinets soon, there are som volume limitations.
(Uppsala, du?)
I also have 1400 cm2 per side for my woofers ( 3 x 12 inch), and also have a big room 10,2 x 5 meters.
My room eat´s dB, and i have mesaured 124 dB from 3,4 meters (don´t know at what hz ), but you can never get "to much"
And that with 25 mm linear xmax, but can take över 30mm.
And i don´t exactly now what theosweden is after, but if he want´s to build a "monsterspeaker" may he leave nothing to chance.
Haha, jag oxå i Uppsala län, fast bor i Bålsta!
/John
Hi Alex, many interesting things from you, thank you for your efforts.
This driver seems to work really good, I can imagine they have a beautiful transients! Excuse my limited knowledge (thats why I need helo with this) but I was thinking drivers with such high fs wasnt able to play this deep.. Looks promising.
What do you think of this driver? https://faitalpro.com/en/products/LF_Loudspeakers/product_details/datasheet.php?id=101030204
Could you do a simulation to compare the two? or comment what you think about the Faital PRO..
Theo
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Interesting to. When I was reading you post i was thinking like you say in the end "
If you measure and "voice" the system at your listening position you will be ok, but just have to live with a less accurate sound as you move closer to the speakers."
I usually measure in the listening position so I bet its going to be great 🙂
Will do, got a few things to do but later tonight I will do some more sims to compare.
Cheers
A.
Cheers
A.
I agree.... you can suddenly do many things, when you have many drivers - opposed to having one. But still, it's a midrange driver, and as one of my good friends always say "if you use a PA driver, you have to translate it into HIFI, by roughly looking at a PA subwoofer = HIFI woofer, and a PA woofer = HIFI midrange.
PA drivers did not invent some magic to achieve higher sensitivity. So a PA woofer has the given high SPL at around 1kHz, not at lower frequencies like HIFI drivers. So when EQ'd flat, you actually get almost the same sensitivity for a PA driver as a HIFI driver - at below 150-200Hz in closed boxes, because.... there is no hidden magic in PA drivers, just a different compromise. Also, most often, measurements of PA drivers are shown with ported designs, and HIFI drivers are often shown with closed or open baffle designs. So again, be careful when comparing them - IME.
Though.... we are talking around 70 liters for 4 x 8" drivers. I would not try and squeeze in 6 drivers. But most HIFI drivers would fit the bill pretty well... especially because there are 8 of them, and he can use EQ to flatten the "bump" that he might get from the higher Q, since the volume is a bit too small.
Again, we're talking 250Hz and below.... this is not midrange territory... and almost any 8" HIFI driver should behave very nicely here - for pumping air.
How much distortion do you think we can hear, from 8 x 8" woofers in two big speakers.... at low frequencies? My guess is - not that much. Tweeter and midrange on the other hand - that is very important... but that is covered absolutely fine by his AMT and Purifi's.
@jawen
Det var inte långt bort! Du får höra av dig om du vill lyssna på ett skapligt öppen baffel-system, spelar inte 124db men låter rätt okej 🙂 bor strax norr om Uppsala.
What I try to achieve... Build two nice looking speakers playing 40-50 hz and up, LOUD if I feel like it.
Much headrom have always been my philosophy.
Det var inte långt bort! Du får höra av dig om du vill lyssna på ett skapligt öppen baffel-system, spelar inte 124db men låter rätt okej 🙂 bor strax norr om Uppsala.
What I try to achieve... Build two nice looking speakers playing 40-50 hz and up, LOUD if I feel like it.
Much headrom have always been my philosophy.
If you only measure in the listening position - you could end up with way too much high frequency, since those fall with distance, as explained earlier on.
@TheoSweden, I agree completely. Any speaker with an f3 anywhere near 50Hz will sound very good on almost all music. Would a lower range sound better? Yes, for some music. But one will be very surprised how very good a 50Hz lower limit can sound. I make this statment from experience.
So.. I now got the cabinets home. Got a really nice feeling when I first saw them! Really nice in reality, more heavy and more solid than I expected 🙂 🙂 🙂
I think I stiffen them up more with a few (1 or 2) walls in every section mor isnt needed.
I have some plans for the outer layer and that will make them stiffer to.
I measured the boxes with some chips for parcels (dont know the english word) and that wasnt as fun. Only around 53 litres in the upper and lower sections and 32 litre in the middle.
Not yet sure now much space the Purifi speakers need, but if possible its easy to take some of the volume from the middle section.
I think I stiffen them up more with a few (1 or 2) walls in every section mor isnt needed.
I have some plans for the outer layer and that will make them stiffer to.
I measured the boxes with some chips for parcels (dont know the english word) and that wasnt as fun. Only around 53 litres in the upper and lower sections and 32 litre in the middle.
Not yet sure now much space the Purifi speakers need, but if possible its easy to take some of the volume from the middle section.
