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Old 26th December 2006, 11:26 PM   #21
bjorno is offline bjorno  Sweden
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Old 29th December 2006, 04:07 PM   #22
kyselym is offline kyselym  Czech Republic
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Join Date: Apr 2006
Location: Kojetin
Hi Bjorno

firstly I really want to thank you for time you spent with me. Not many so skilled people like you are so patient with people like me(not so skilled)

is it your opinion you have also 2 L21 subs that are more ‘blameless’ than your L26’s closed subs?

Do you blame the speaker box or the drivers?
I don't blame drivers. I know they are good, they just need proper enclosure and overall design.

fast: it is really a problem to describe. I used to have not a good amp(yamaha rx396) but I tweeked it into very powerfull and fast amp. (high slew rate and high DF with 2x135w to 4ohm). Speakers are same. Before I tweeked it, bass was only huuu huuu and I could easily see cone highly moving. Now bass is realy tight and strict. I think it is because of high DF so dirvers "listen" to amp and do excatly what amp "says". But I have this feeling only with L21 subs. I still can hear some huu huu or boomines, or how to call it, with L26 subs(I'm absolutely sure I made something wrong but it doesn't matter now, I want to redo). It is not so critical but not as prefect.
I don't have all amps for HT complete(amps are not in box and only on testing heatsings). Just this stereo amp. I'm working on amps but I need to solve this subwoofer thing to continue (because it's amp(s) will be in one box with the others... and will work as a stand for other equip, center and TV)
these are the crossovers suggested by Tony Gee that I use (not measured, just simulations) I don't have any measuring euqip.
(I should have posted this crossovers sooner - sorry)Now It is some kind of 5.0 system instead of 5.1 but I would prefer 0.1 real sub(or subs but with separated source and amps). Also when doing all this I decided to build another dd8 (add rear centrer) to have 6.1 as more films are coded in 6.1 and it will not cost me much as I have drivers at home.

I use subs as stands you are right. The rear wall of sub enclosure is about 30cm from rear wall (dd8's about 50cm) side is about 30-40cm. L26 subs are 465mm deep, 740mm tall and 360mm width. L21 subs are 465mm deep, 695mm tall and 295 width(cannot afford more than 1m distance from front baffle to rear wall - now it is less)

Reason why I think that L26 can not do 20Hz is that I made simulations in unibox with clasic reflex box and was unable to get cone excursion in safe range, port length and air speed as well and finaly step response. But this doesn't mean they realy can't...I'm not so skilled as many here(and you) and don't understand all this things so much for now I go through MJK's site but I'm not sure if it is right?: You are absolutely right I haven't done my homeworks well I will redo

I can buy 2 more L26 for rears and there will not be probably big problem to have 4x L26 subs if the outside dimensions will not overcome those 0.942 x 0.442 x 0.438 you suggested, too much. I have no problem to drive 2ohm load (parallel 4 x L26) the maximum power amp I can build is 1200W into 2ohm. I'm able to build only power amps not AV preamp so for this purpose I thought of some AV preamp (for example the NAD cheapest) I can have subsonic filter:15 - 80Hz 24dB/oct, cross to satelites 30 - 180Hz 24dB/oct and parametric eq 30 – 150Hz, +/-10dB Q=4. When I did some simulations of L18 in closed I thought of crossing to sub at 100Hz because of xmax. Is it a good idea? Also I hoped that L26 will have more impact and higher power load so I want to cross as high as possible not to compromise sub localization. I thought if I have 4 subs(one in each corner) this localization wouldn't be a problem even if crossing at 150hz.

ok Bjorno now you know my situation completely It seems you know excatly how to do it so what are your suggestions? What should I do differently and which sub to build?
my current idea is: I let those DD8 closed, build 4 of those 132.5L boxes you simulated with L26. Final integration of DD8s with subs shouldn't be a problem, I agree (active crossovers will make it a lot easier). But don't know how to amp subs. Not sure if build one amp for all and then parallel or build two amps and divide. Also don't know how much powerfull amps should be to supplement 6 DD8 at max power level. I'm not mad if you start to think it is just because I'm doing this HT gear for whole life, I hope, so I want it as perfect as possible. I don't want to change something after 5years when I find out that something is not sufficient. On the other hand, I don't want to do it at all cost
Finaly I would like to have as big impact and strong, tight bass as possible. I'm sure of strong and tight when looking at simulations you posted but have no idea what impact to expect. I realy like the sound of kick drum but I never heard it with such impact on my speakers as I can hear them on liveshow or concert This started my idea with profi sub with beyma 15K200 but wasn't sure of quality.
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Old 30th December 2006, 09:26 AM   #23
kyselym is offline kyselym  Czech Republic
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Join Date: Apr 2006
Location: Kojetin
Hi Bjorno

I searched MJK's site to better understand what is ML TQWT and found (for now) only this article (design) :
I'm not sure if I got it right. I understand ML is mass loaded(like port or passive) but the short TQWT means tapered quater wave length tube and when looking in galery
many projects marked ML TQWT doesn't seem to be tapered as well as the your simulation for L26. I think I have some idea aboout mltqwt but I thought that this tapering has effect on performace (S0 and Sl and modes) how should I read those cabinet drawing in your simulations?

have more questions but I think it will be better to go step by step
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Old 30th December 2006, 01:12 PM   #24
kyselym is offline kyselym  Czech Republic
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Join Date: Apr 2006
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hi again
I'm going through that article whole day again and again and still don't understand this:
MJK searches the differences between tapered transmition line, folded TQWT (tapered quater wavelenght tube) and straight TQWT. (page 9 of 76 in ML-TQWT.PDF - original design options followed by figures 3,4 and 5) I understand why the first one is tapered transmison line(it tapers from S_0 to S_L) abut the second (figure 4) should be extended transmition line because it extends area towards terminus. And I'm absolutely lost with the figure 5. (straight). I think it is also extended one or not? can somebody explain me this? what are the differences? why the L26 simulations bjorno did is ML-TQWT (why it is tapered?I can't see any tapering)? tapering acording to MJK shortens length of line but he finaly selected the longest option that brought resonances down to 40Hz. why? if he did that with tapered he should get there with smaller enclosure. What I get worng?
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Old 5th January 2007, 01:28 PM   #25
kyselym is offline kyselym  Czech Republic
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can somebody answer my stupid questions please? I don't want to ask MJK with this.
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