Larger Semi-Omni Development

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SteveTheShadow
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Re: Larger Semi-Omni Development

Unread post by SteveTheShadow » Sat Jul 29, 2017 7:19 pm

One pair of roughed up bass boxes:
Image
Bracing etc will be installed later this week.
BTE Designs modified Lenco L75 idler turntable, Rega R200 Tonearm, Goldring E3 MM cartridge, NVA Phono1 phono stage.
Mac-Mini music server with iTunes, AppleTV4 media streamer, Musical Fidelity M1 DAC,
NVA A20/P20, 25WPC stereo power amplifier/passive control unit,
own design, semi-omnidirectional, transmission line speakers- "The Flatback Banned".

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karatestu
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Re: Larger Semi-Omni Development

Unread post by karatestu » Sat Jul 29, 2017 8:04 pm

Hi Steve,

This is a fascinating thread and one i am following closely because of the project i have on the go.

I have never heard an omni or semi omni but whilst doc modding a pair of Marantz imperial 7 (3 ways with 12" woofer) i decided to make up a very small box for the mid and tweeter so i can play around with having the mid up firing. Of course what i am doing is just using an old pair of 70's speakers, ripping everything out and shoving in some of the docs ready doped drivers and a ton of steel. If i dont like it then i will not have butchered my cabs for no reason.

I am very excited about trying the semi omni version and if i like it i will then cut a hole in the top of the Marantz's cabs and then i am fully committed.

Bracing myself :clap: for your next installment

Stu
Naim, Linn & Harbeth fanboy

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SteveTheShadow
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Re: Larger Semi-Omni Development

Unread post by SteveTheShadow » Sun Jul 30, 2017 11:15 pm

Been researching 1960s and '70s radiogram images this afternoon, and the speaker grille variations from this era are fascinating in either their beauty or their sheer hideousness.

For the bass boxes, I'm going for a two part front panel trim; the upper half being plum coloured rexine in the grand Dansette tradition, whilst the lower grille covering the bass driver is a cream coloured basketweave, behind 2" spaced, half inch dark hardwood square section, polished vertical slats. Veneer will be blonde wood.

I'm going all out for the early 1960s look for these speakers, because the wider than deep profile is never going to compete with the tall, slim, line arrays normally found in today's hi-fi rooms. These will be the polar opposite of everything that common sense says the modern listener wants.

Forensic dissection of the music is out, hyper detailed sterility is out, pinpoint imaging is out, hi-fi is right out.
Warmth is in, room filling widescreen presentation is in, fun is in, music is in. Hi-fi can go stick itself where the sun don't shine. I no longer care about hi-fi. I'm building for me and if others like what they hear, that's great; if they don't then whatever. I am building what I believe in, I'm not about to be second guessing all the time, playing non stop fecking catch up. That modus operandi is just a recipe for mediocrity.

Have cut the depth down to 11.5 inches which has pushed the internal volume of the bass box down to 2.3 cu ft, pushing the bare box qtc to 0.95, however the stuffing, if done properly, should pull the volume seen by the driver back up a bit.

Fitting the back on with duck tape, laying the box on its back, shoving a BAF filled cushion inside and dropping the driver in, it passes my cone tap test beautifully, giving just a dull thud, with no echo and that without any bracing or lining, so things look good for the bass boxes.
BTE Designs modified Lenco L75 idler turntable, Rega R200 Tonearm, Goldring E3 MM cartridge, NVA Phono1 phono stage.
Mac-Mini music server with iTunes, AppleTV4 media streamer, Musical Fidelity M1 DAC,
NVA A20/P20, 25WPC stereo power amplifier/passive control unit,
own design, semi-omnidirectional, transmission line speakers- "The Flatback Banned".

Chunk McDaniel
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Re: Larger Semi-Omni Development

Unread post by Chunk McDaniel » Mon Jul 31, 2017 4:57 am

Sounds as though these speakers will be a thing of beauty Steve. Good on you building for yourself and leaving the stade boring ultra fussy and narrow minded hifi rules behind. It is often the Mavericks of this world who go on to do great things. Just look at the world's great musicians I wonder how many sat down with the hit record for dummies book. No they went out on a limb did their own thing and did things their way. Good on you fella!

antonio66

Re: Larger Semi-Omni Development

Unread post by antonio66 » Mon Jul 31, 2017 6:00 am

Another great read for a non DIY'er. :)

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SteveTheShadow
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Re: Larger Semi-Omni Development

Unread post by SteveTheShadow » Mon Jul 31, 2017 12:00 pm

Aye,
There's no in between with mavericks. You either become a zillionaire or starve in your ill lit garret. :lol:
I'm at the time of life when I couldn't care less now though.

I've been a bit of a misfit for most of my life and have spent decades fighting with the maverick impulse. Perhaps that's why I like it here, as maverick characters tend to be welcome, whilst jobsworth conformists can't handle it, stick out like sore thumbs and are usually given the heave-ho.
Nothing annoys me more than conformist tossers, pontificating and passing judgement from on high as if they have the monopoly on what is good music reproduction and what isn't. "Its nothing personal" is the favourite cop out that these people will use to try to assert themselves when they feel threatened by left field ideas. 'Course it's bloody personal!

I don't know for sure whether it is the maverick impulse, or the fact that I've been forced (sometimes threatened into) toeing the line for much of my life and consequently have had to attempt to suppress said impulse, that has been the cause of my recurrent depressive illness over the past twenty years.

Now I can do what the hell I like, the depression has lifted. :mrgreen:
BTE Designs modified Lenco L75 idler turntable, Rega R200 Tonearm, Goldring E3 MM cartridge, NVA Phono1 phono stage.
Mac-Mini music server with iTunes, AppleTV4 media streamer, Musical Fidelity M1 DAC,
NVA A20/P20, 25WPC stereo power amplifier/passive control unit,
own design, semi-omnidirectional, transmission line speakers- "The Flatback Banned".

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terrybooth
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Re: Larger Semi-Omni Development

Unread post by terrybooth » Mon Jul 31, 2017 4:28 pm

SteveTheShadow wrote:
Mon Jul 31, 2017 12:00 pm
Now I can do what the hell I like, the depression has lifted. :mrgreen:
And long may it be so. :grin:
Pioneer PL71/DL103/ Phono2/HiFiPi/P90SA/TIS/CubixPro two-up

Chunk McDaniel
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Re: Larger Semi-Omni Development

Unread post by Chunk McDaniel » Mon Jul 31, 2017 10:27 pm

Nice one Steve. Now go blaze that left field trail.👍

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SteveTheShadow
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Re: Larger Semi-Omni Development

Unread post by SteveTheShadow » Tue Aug 01, 2017 11:31 pm

Aye, sod that po-faced conformity. I ain't working like that no more
I'm hoping to resume the build tomorrow.
BTE Designs modified Lenco L75 idler turntable, Rega R200 Tonearm, Goldring E3 MM cartridge, NVA Phono1 phono stage.
Mac-Mini music server with iTunes, AppleTV4 media streamer, Musical Fidelity M1 DAC,
NVA A20/P20, 25WPC stereo power amplifier/passive control unit,
own design, semi-omnidirectional, transmission line speakers- "The Flatback Banned".

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SteveTheShadow
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Joined: Thu Sep 12, 2013 5:24 pm
Location: the Aether
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Re: Larger Semi-Omni Development

Unread post by SteveTheShadow » Wed Aug 02, 2017 2:25 pm

Here is the finalised retro design drawing for these speakers.
all sorts of influences there.
Top box smacks of Mr Exeter's Interocitor.

Image
BTE Designs modified Lenco L75 idler turntable, Rega R200 Tonearm, Goldring E3 MM cartridge, NVA Phono1 phono stage.
Mac-Mini music server with iTunes, AppleTV4 media streamer, Musical Fidelity M1 DAC,
NVA A20/P20, 25WPC stereo power amplifier/passive control unit,
own design, semi-omnidirectional, transmission line speakers- "The Flatback Banned".

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