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Old 23rd June 2009, 05:47 AM   #1
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Default 90db in 10L f3 of 35hz !?

Hello,

I'm just seek to understand how ProAc have done the TriTower ...

The bass enclosure section is about 10L only. This loudspeaker is 90db efficiency and have deep bass from 35hz with floor port.

I want to build an enclosure of 7L with proportional bass response from f3 of 90db.

But i search while hours on the net and speaker list and WinISD and never find a method to reach this kind of performance.

Is that someone who already done this before ?

If yes, you du he do !?

This subwoofer will be the "stand" of a pair of mini monitor with Fostex at 90db. So i need efficiency like the ProAc TriTour and, again like this product, no active XO or subwoofer amp.

Just try to do something already done but i don,t have enough knowledge to find the secret myself :P

Thank's!
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Old 23rd June 2009, 11:27 AM   #2
Henkjan is offline Henkjan  Netherlands
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35Hz, is that the -10dB point?
90dB with 3 units paralel should not be a problem...
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Old 23rd June 2009, 01:04 PM   #3
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Quote:
Originally posted by Henkjan
35Hz, is that the -10dB point?
90dB with 3 units paralel should not be a problem...

I don't know about -10db.

One thing i know. i own Mission 701 with 60hz specs and when you hear ProAc a lot more lower and better bass.

remember that the important is the feeling and the listening pleasure at the end. Not the specs or curve etc. There is maybe a difference between build a speaker for talking about it and buil a speaker for listening.

I have a good pair of DIY here with good response curve an bla bla specs and nobody like the sound because it's too "high" or "hard".

Firts a tough my speaker have a problem but i build a little pair of monitor with good Fostex flat fullrange and i find the same "signature" in the sound that people dislike.

I have a pair of Monitor Audio RS8 and it's sound amazing to this people but i discover that the mid-bass are atenuate and the sound is modeled to obtain what the customers like.

anyway, return to the topic !

I build a 7 litre box (i can restart with little more volume if absolutely necessary). I want F3 of 60hz and 90db 1w 1m 100hz.

Deeper is better too so if i can do more

Thank's !
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Old 23rd June 2009, 04:35 PM   #4
jbell is offline jbell  United States
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If you can go up to 10liters, instead of 7, things get much better for a MCM 55-2421. I'm sure others can post a better design, but this could be a starting point.
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Old 23rd June 2009, 04:39 PM   #5
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Keep in mind, numbers are used to sell loudspeakers and so presentation and omission is everything.


In acoustics on the other hand where science dictates measurements, one would find that if you used ALL of your 10 L as the enclosure volume and had the port and cabinet walls external, then for a –3dB point of 35Hz, the highest possible sensitivity you could achieve, using the “perfect driver” for the B4 alignment, is about 82.dB, 1W 1M.
You pay roughly a 9 dB per octave penalty in efficiency when you lower the low corner an octave and keep the box volume fixed.

To get an F3 of 60Hz with 90 dB 1W1M in a B4, requires about 12 L and of course the right driver and port.

Low bass is big and heavy even when you can cheat Hoffman’s iron law a little. A B4 alignment (simple ported box) is not your only option.
Best,
Tom
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Old 23rd June 2009, 05:25 PM   #6
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Quote:
Originally posted by Tom Danley
Keep in mind, numbers are used to sell loudspeakers and so presentation and omission is everything.


In acoustics on the other hand where science dictates measurements, one would find that if you used ALL of your 10 L as the enclosure volume and had the port and cabinet walls external, then for a –3dB point of 35Hz, the highest possible sensitivity you could achieve, using the “perfect driver” for the B4 alignment, is about 82.dB, 1W 1M.
You pay roughly a 9 dB per octave penalty in efficiency when you lower the low corner an octave and keep the box volume fixed.

To get an F3 of 60Hz with 90 dB 1W1M in a B4, requires about 12 L and of course the right driver and port.

Low bass is big and heavy even when you can cheat Hoffman’s iron law a little. A B4 alignment (simple ported box) is not your only option.
Best,
Tom
The project look and design is already fixed. I have minimonitor who need stand. If i build stand larger and or deeper than speaker, it will look ugly and good sound and i can do many other big bass speaker in the ugly domain. And marority far more efficiency and low...

The minimonitor with Fostex Fe107e is about 90db. I can do one thing to help me to reach best overall response. I can atenuate the fullrange a little bit.

If a build my enclosure two inches taller and with ½" MDF instead of ¾" (i will grow to 10L cabinet) and i attenuate the Fostex from 90 to 87db ? Can I expect good response with propre driver ?

External dimension : 28 inches high (including about 1in spikes) 5" wide and 8¼" deep. The universe stop to this limits :P

I almoast order the Silver Flute W17RC3804... Few, i say your reply just at time !

The WinISD cure of SilverFlute doesn't look like one in the spec sheet. The Solen guy said that is a good choice for my setup but the MCM 55-2421 curve look better if i use 10L

thank's for your help !
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Old 23rd June 2009, 05:28 PM   #7
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Quote:
Originally posted by jbell
If you can go up to 10liters, instead of 7, things get much better for a MCM 55-2421. I'm sure others can post a better design, but this could be a starting point.

Hô it's almost better than my MTM 5090cubic inches tour ! i,ts like 40hz f3 !
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Old 23rd June 2009, 05:36 PM   #8
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oups i think i will have difficulty to fit 8 inches because my inclosure is 8.25 outise with angled baffle to i can't go bigger than 6.5 inches
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Old 23rd June 2009, 05:57 PM   #9
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Quote:
Originally posted by Tom Danley
Keep in mind, numbers are used to sell loudspeakers and so presentation and omission is everything.


In acoustics on the other hand where science dictates measurements, one would find that if you used ALL of your 10 L as the enclosure volume and had the port and cabinet walls external, then for a –3dB point of 35Hz, the highest possible sensitivity you could achieve, using the “perfect driver” for the B4 alignment, is about 82.dB, 1W 1M.
You pay roughly a 9 dB per octave penalty in efficiency when you lower the low corner an octave and keep the box volume fixed.

To get an F3 of 60Hz with 90 dB 1W1M in a B4, requires about 12 L and of course the right driver and port.

Low bass is big and heavy even when you can cheat Hoffman’s iron law a little. A B4 alignment (simple ported box) is not your only option.
Best,
Tom
Yeah i know the manufacturer use sort of specs playing and sometime fool customer. I don't stiff on the specs here. Just want warm and interesting sounding mini tour speaker. A bit like Rega small tour with side mounting woofer. This boxes are already split volume inside i think. In my case, i only make two separate enclosure.

If you know how to reproduce he bass presence and efficiency "illusion" of the TriTower, i will add it to my sound system because it satisfied me for this kind of project. I prefer to be comfortable in the fake than stay the speaker in my locker because they sound shy and gramophone like.

This is an hybrid project. If a wan, i disconnect the mini-monitor from the base and enjoy a true fullrange hi-fi with no bass. But when i want more warm and relaxing ambience, i plug it trough the base ! And if i want, i can use the mini-monitor anywhere in the house. It's small enough to be transportable
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Old 23rd June 2009, 06:06 PM   #10
jbell is offline jbell  United States
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can you fit the 8" driver on the back side of your stand if it's 8.25" wide? Wall loading will help bass as well from the 55-2421's.
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