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-   -   Need sub suggestions <150l, directional! (https://www.diyaudio.com/forums/subwoofers/209301-sub-suggestions-150l-directional.html)

bjorno 17th September 2012 12:28 AM

1 Attachment(s)
Quote:

Originally Posted by KaffiMann (https://www.diyaudio.com/forums/subwoofers/209301-sub-suggestions-150l-directional-post3162353.html#post3162353)
:)

The difference is where the first room reflections originate.

I have no good explanation for it, other than with the TH, I had mainly 40hz and nulls although it was designed 0db at 80hz evenly down to -5db at 19hz, works well in other rooms. Now I have a very even response, and a minor boost at 80hz.

Hi Kaffimann,

A late sim. contribution I couldn't post earlier than now : See the picture.

Questions: How many T-TQWT subs have you built? and have you tested your set-up with(without) the TH?: What's your impression of the SQ?

b:)

KaffiMann 18th September 2012 07:53 PM

Quote:

Originally Posted by bjorno (https://www.diyaudio.com/forums/subwoofers/209301-sub-suggestions-150l-directional-post3167662.html#post3167662)
Hi Kaffimann,

A late sim. contribution I couldn't post earlier than now : See the picture.

Questions: How many T-TQWT subs have you built? and have you tested your set-up with(without) the TH?: What's your impression of the SQ?

b:)

I have built 2 of these T-TQWT's, the brief tests I have conducted so far seem to give way much higher SQ than from the TH. A lot faster response/better timing. But I have not had the time and/or opportunity to test with both at the same time yet, I will take some pictures and post them along with a short comment on the sound when they are finished.


They are currently at a car paint shop, I just got 1 of them sanded down yesterday, took me the whole evening, I have never seen wood shine with no oil, varnish or coating before. It is beautiful. The harder parts of the wood reflect the light differently than the softer parts, we tried sanding the top up to 800 paper, it is very smooth and good looking.

I am torn between finish choices here, the original idea was to use a chestnut+ cherry varnish mix to get a darker and warmer glow, then coat with silk-matte clear finish. I was considering going black metallic for a while (will do that for the amp boxes and the access lid on the T-TQWT's), and now I am considering just adding a silk-matte clear finish to show off the somewhat rough ply boxes sanded down beauty more.

Edit:
I forgot to mention.
I build two for myself, and a friend of mine is also building 2 for his HT.

KaffiMann 22nd September 2012 09:31 AM

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Bjorno:

Is this feasible?

I've been playing about with OD designs and I've seen you post some of them as well, have been thinking about how low can you go with a reasonably flat response, dreaming of 15hz at <150L... :-)

This is scalable up or down in frequency, just keep all the lengths at the same ratio to each other.

Edit:
I experimented with lengths and sizes A LOT to get to this point, it seems that if you find the correct size for S1, it can be scaled down and not impair frequency extension much, this seems only valid if you have similar lengths at L12 and L23, but I have no idea if it will work.

Edit2:
there is nothing in the way of adjusting L12 to reduce size, but smoothness, extension and phase will be heavily influenced.

bjorno 22nd September 2012 02:12 PM

1 Attachment(s)
Quote:

Originally Posted by KaffiMann (https://www.diyaudio.com/forums/subwoofers/209301-sub-suggestions-150l-directional-post3174407.html#post3174407)
..Is this feasible?.. but I have no idea if it will work..

Hi Kaffiman,

Your design is feasible and will work fine! The submitted picture:

I've made quite a few of very similar designs starting ~ 30 years ago.. ended using the Peerless 830452 when first released with designing a IME very good sounding Sub used from ~ 15 Hz to~ 50 Hz that I had tailored to fit a huge bookshelf, placed at the dead center in the system set-up.

Later I started to use Aluminium drivers in OD-TL and recently( a few years) only in T-TQWT's/T-QWP's or T-MLQWP's that sounds IMO superior and act like point-sources.

b:)

KaffiMann 22nd September 2012 04:33 PM

Quote:

Originally Posted by bjorno (https://www.diyaudio.com/forums/subwoofers/209301-sub-suggestions-150l-directional-post3174650.html#post3174650)
Hi Kaffiman,

Your design is feasible and will work fine! The submitted picture:

I've made quite a few of very similar designs starting ~ 30 years ago.. ended using the Peerless 830452 when first released with designing a IME very good sounding Sub used from ~ 15 Hz to~ 50 Hz that I had tailored to fit a huge bookshelf, placed at the dead center in the system set-up.

Later I started to use Aluminium drivers in OD-TL and recently( a few years) only in T-TQWT's/T-QWP's or T-MLQWP's that sounds IMO superior and act like point-sources.

b:)

Very interesting.

Since I am getting rid of my TH I have nothing to put my TV on, considering building something "extra" to act as a stereo and TV bench :-)

Not sure if my wife will approve yet, but she was the one complaining over moving out the over 300L TH in the first place :-P She likes it, and it keeps the kids away from all the wires.

So all in all I have about 200-250L worth of space if I fold it right + materials(preferably 150x60x36 cm or less including material, a little bit higher than the TH), looking to press out a little extra in the lower regions if possible. Goal is basically as low as possible from 30hz down at 110DB or better in halfspace, max power 300W regardless of impedance. Silly and near impossible, but still a goal.

So I am just going over the options. Waste of time?

KaffiMann 23rd September 2012 03:43 PM

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Acoustic peak at 12,22hz, the simulation is below xmax all the way down at 40V.
Maybe a 10hz HP would be smart, I imagine LP at 50hz, phase=0 there.. May also be a benefit to glue the driver tight to the enclosure, I've found this to reduce needed xmax before.

I do not have enough room for this, but a guy can dream.

Edit:
Not bad for 490,2L?

KaffiMann 14th June 2016 06:41 PM

2 Attachment(s)
Sorry about the bump.

I got some questions regarding the beyma 12br70 and thougth I'd better post some pictures of their current life. Works pretty well, certainly given me a reputation in my new neighbourhood.


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