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Old 13th May 2012, 01:47 PM   #51
jimbro is offline jimbro  United States
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Nice. I'm also a little surprised it work so well in that small of a room. Mine's about 1/3 smaller than that so don't know.
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Old 13th May 2012, 02:03 PM   #52
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Quote:
Originally Posted by Bob Brines View Post
Of course you insulted me. You insult people on this forum as a modus operendi. You have no clue what my system sounds like. Woof heard it. But Woof is obviously wrong because he contradicts you prejudices. Perhaps you have heard of F.A.S.T. Get's discussed here every once in a while. Little driver over a big bass. My system is an extension of this.

Perhaps you might tell us why my system won't work. Obviously you are far more expert than I.

Bob
I have not insulted you because the simple Logic don't allow such thing, but if I knew that your ego is so big, then I would not say anything... with that "modus operandi" claim you tried to insult me, but I'm not insulted because you have no proof for such claim(it's simply not true- you can browse trough forum)... And my attention was not to insult you, what I allready said... Forum communications can be problematic as we saw it.

But again my opinion about units dimension is that it has to be relatively in Size(at that XO) if you want it to sound authenticaly the best it can...

I apologize(for posting in your thread it won't happen again), and no hard feelings

Cheers
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Old 13th May 2012, 08:54 PM   #53
DogStar is offline DogStar  Europe
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Is it all it takes for somebody to be insulted. I must say that I am quite surprised how little it takes before people around here becomes defensive.

Quote:
Originally Posted by woof View Post
Live or behind the shield of a computer, you just insulted a very respected & knowledgeable designer, WITHOUT even hearing the design. I had the opportunity to hear this design at LSAF last week. It does not disappoint. Bob freely played any genre of music that visitors requested.
Is it so that because a designer is respected and knowledgeable, no one should dare to question or criticize his (or her) work? As far as I know, people on this forum frequently express opinions about loudspeaker drivers and design they haven’t heard.

I hope i didnt insult anybody

Last edited by DogStar; 13th May 2012 at 08:59 PM.
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Old 13th May 2012, 09:38 PM   #54
mightym is offline mightym  United States
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I heard these at the Lone Star Audio Festival.

I also heard the MLTL's Bob had on hand.

I thought both sounded wonderful. Perfect, no, but then we are talking about a hotel room here. There were a large number of exhibitors in attendance who had ~6.5" w/ Tweeter either in MTM or TMM arrangements that just drove me out of the room with the bass bloom in the lower mid bass. It's difficult to bring a combo that will work well in these rooms.

I would rank Bob's efforts as some of the best of show.

I was unaware that this thread existed until today, I actually went to the show hoping to hear his MLTL's, and was not dissapointed. The OB's were like icing on the cake.

I've met Bob at the show a couple of times now, and enjoyed each one. LSAF is unique in it's blend of high end botique and DIY, it's become a ritual for me to attend, and I've enjoyed every year more than the previous.

John
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Old 13th May 2012, 10:37 PM   #55
T101 is offline T101  Bulgaria
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Since page 1 I’ve been thinking of how to replicate the original sound of the bigger baffle, but with narrower one.
I did it too. First, I made an even bigger OB, which was terribly ugly and a waste of plywood too as FR driver choice was poor
Then I made a smaller 8x12 in baffle and suspended it in order to have four open edges as I had only the Tolvan Data EDGE (didn’t had the MJK Mathcad sheets then as the sole Idea of Math%$@0# was frightening), which is unaware of boundaries, or floor, so I had to have a dependable simulation - voala the suspended OB was born.
Then I put on it a more efficient Fane 6 inch midrange and had the required headroom to fill in the hole.
Then the problems began, the system became more sensitive to placement, the bass was not quite the same. Then I read more and then it came to me... The OB is an integral part of the H frame... some self education follows... Then it is either 6db eq@<30hz or the bigger OB, then the placement... Then it struck me, why don’t I have a look at the original design simulations just to see where, how and why the H-frame extends.
And finally:

Well, small baffles do exist, you just have to make them work for you
You don't follow the same guidelines with small baffles, it's just the opposite, you must flaw them to have the room to shave the excess and be left with the proper performance.
Right now, I fired up the edge, just to recall.
See what happens if you center the FR@125x125mm relative to the lower left corner on a 250x350mm baffle (centered 4.9in above the lower edge of a 10x13.78in baffle).
- you get 200 Hz@-5 or -6db relative to 2 kHz, and a 4 db peak with ~4db/oct slopes - e.g. solvable with LC 1st order notch with lowered Q such as higher dcr inductance, both centered at 1 KHz.
Maybe 1st order passive crossover, L-Pad or a single series resistor, RLC notch and a Zobel. Or maybe there is a more elegant way for achieving the same, but I’m not an engineer so this way serves me as a listener.
Then maybe a properly aimed LR-4 and it should be beautiful or since you already have the -6 db point, you can add 1st order cornering lower (175hz?) and a greater order cornering at FR driver Fs?
Then the H frame, my system is passive and I am completely happy with 13 mh and 150uf, just adjusted the OB to it with some additional crossover work, padding, the padding required impedance equalization and etc., but the musicians were given permission to enter the room

Slightly on another track, the H frame told me that the saying for the non-directional ever protruding never reflected bass were just that sayings. You have to hear them with the original big OB's to know how much of a shield it actually is, not only an aid for the FR.

Best regards!

P.S. almost forgot welcome to the Goldwood community... And... I originally wanted to protest about the dead under 30 claims, but you heard Organ I purchased the Bach Complete Organ Works, never mind it's at least 1/2 German funeral music, it's deep! And there are some well recorded bass drums across my collection which light the 20 Hz bulb on my EQ and it makes a difference to have the 1858 on the other end of the wire maybe smallest match amongst known speakers are mine 15 in 16.6 Fs Daytons in 200+L EBS doghouses
Beat regards again!

Click the image to open in full size.

Last edited by T101; 13th May 2012 at 10:58 PM.
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Old 13th May 2012, 10:52 PM   #56
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When i made my ob's nobody believed that they would reach below 700hz.
I managed to push mine down 350hz before doing the tweaking with a frequency within +/- 3db, before putting in a xover.
In Norway we have this constructor who have been pushing boundaries with putting elements in builds they shouldn't been working. I believed he said that there were no fun in trying out things that already had been tested.
I believe that there are some x-factors, things not possible to figure out.
Building speakers is one of them.
When a element is tested and measured, its done in "dead-chambers".
No reflections make it not possible to know for sure how it will work out in an OB.
I guess doing equations conserning how a speaker would act is safe, but i believe there are many kinds of truths.

So saying that Bob is wrong is not right, unless uve tried it yourself.
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Old 13th May 2012, 11:49 PM   #57
woof is offline woof  United States
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Quote:
Originally Posted by DogStar View Post
Is it all it takes for somebody to be insulted. I must say that I am quite surprised how little it takes before people around here becomes defensive.



Is it so that because a designer is respected and knowledgeable, no one should dare to question or criticize his (or her) work? As far as I know, people on this forum frequently express opinions about loudspeaker drivers and design they havenít heard.

I hope i didnt insult anybody
Quite the contrary - opinions are and should be welcome for a forum to be useful. But statements of fact such as "no way", "you simply can't" and "that is far from what realistic sound production should be", without actually hearing the design, are insulting to any member that has shared his knowledge & designs to many on this and other forums.

Martin King's spreadsheets are used by hundreds of DIY'ers. On his web site is an H frame sub, full range driver on top combo that has been built by quite a few people. Jim Griffin's H frame sub with an Alpair full range which he has posted, was voted best in it's class at a major DIY event. The concept does work. As Bob pointed out, there are numerous threads about the F.A.S.T. concept.

But to be fair, this is my opinion - that I supported by hearing Bob's design, and several others that use the concept. I also referenced several other successful designs by some of the other respected contributors to our hobby.
Any opinion that does the same would and should be welcome on this and any other forum.

As I feel that this has become unproductive to Bob and his design, this is my last post regarding it. And no, you did not insult me.
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Old 13th May 2012, 11:54 PM   #58
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Although it sounds against logic or more correctly against "conventional practice" to match a big heavy woofer with a light 4" or 3" wideranger, the whole concept of a FAST is based on this: a light full range driver with a helper woofer. Many, starting with the founder of this concept , Martin find this configuration to also provide benefits of full range sound with no crossovers in the critical range.

Looking at typical crossover points around 300-400Hz, it is noteworthy that the woofer actually does not have to move very fast even if when reproducing the highest frequency it is asked to play at i.e. ~400Hz. On the other hand the widerange driver is light enough to move fast to reproduce 20 KHz, but at the same time should not have any problem moving as slow as the woofer at ~400Hz.

So I fail to understand the concern about matching hugely different driver sizes of different weights. The only area of concern might be the narrow polar response of a large woofer when asked to play at very high frequencies. However if crossing at 300Hz the shortest wavelength produced by a 15" woofer is 1/3rd of the woofer diameter, and only 1/4th for a 12" woofer, that should not cause obtrusive beaming at higher end of the woofer bandwidth.

I dont know if my above understanding is wrong or I am missing something here ?!
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Old 14th May 2012, 01:10 AM   #59
Bigun is offline Bigun  Canada
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Quote:
Originally Posted by Godzilla View Post
I like Dynablasters artwork.

He just doesn't think this kind of setup will work great.
I just checked out the website, looks pretty cool. I don't think there are many of us 'technical types' on this forum that create that kind of art. Reminds me that there is a diverse range of people on a forum like this and it can be difficult for all of our 'styles' to adjust to the local on-line 'culture'.
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Old 14th May 2012, 01:42 AM   #60
kevinh is offline kevinh  United States
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Quote:
Originally Posted by DogStar View Post
Is it so that because a designer is respected and knowledgeable, no one should dare to question or criticize his (or her) work? As far as I know, people on this forum frequently express opinions about loudspeaker drivers and design they havenít heard.

I hope i didnt insult anybody

First I haven't heard these speakers and know nothing about them.

In reading thsi thread, today for the first time I would observe the following, the designer pointed out the faults of the first try at thOB, other posters offered suggestions and where they think problems could be. Bob seemed receiptive to the suggestions while pointing out the constraints he is placing on the design.

Bob then found problems and was happy with the results while again acknowledging what the shortcomings of the speaker are.

For someone like me to come here and say something can't work and basically can or cannot do without hearing the speaker seems a bit rude and yes insulting. There was nothing that Bob said that called for that sort of abrasivenes.
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