"The Flatback Banned" OmniMet

Dedicated to those large boxes at one end of the room
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pre65
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#91 Re: "The Flatback Banned" OmniMet

Post by pre65 »

Dennis (DQ) I think you are just a shiller for NVA. :lol:
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#92 Re: "The Flatback Banned" OmniMet

Post by Daniel Quinn »

You think of lot of irrelevant , poorly substantiated garbage.
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#93 Re: "The Flatback Banned" OmniMet

Post by Dr Bunsen Honeydew »

Semi omnis as in Cubes and Flatback are based on the design principles of Roy Allison (I posted links to his patents). Normal speakers do not take the room into account and the influence surfaces and size have. The original idea was developed at AR (Acoustic research) with the LST expanded later on with the 10pi to account for the dispersion characteristics of no near surface to one near surface to two near surfaces. The work at AR was by Roy Allison and he took the concept further with his own company. Basically it means the room is incorporated in the speaker design and considered to be part of the system. Normal point and squirt speaker fight the room so you are always trying to integrate and the bigger the room the less problems (Owston) which is why the Doc Mods B&Ws worked there and the flat backs and the Cubes it seems didn't.

There is one thing this is about and one thing only, because Steve has adopted this approach (not mine Roy Allisons) and he now uses NVA amps and cables and Phono stage he is seen as a supporter of me by them. They have failed to get rid of me so Steve has become a secondary soft target for them as they percieve it to be a way to hurt me, they are seriously sick people.

I have posted this at HFS.

Re: Larger Semi-Omni Development
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Post by Dr Bunsen Honeydew » Fri Jun 30, 2017 12:03 am

Just to add a little forum politics to explain Steve bringing this here. At Audio-Talk Noddy and Greg have tried their hardest to get me to leave or for Nick to boot me, it hasn't happened and I still stand up for myself and fight my corner. Having failed they have turned their frustration onto Steve, and an absolutely disgusting attack on Steve and his designs came from Greg, and slimy willy mouthed backing from Noddy, as is his way.

I welcome Steve and his projects that are well worth the investigation, but I am equally sad that he has allowed them to win a small battle and take away *what they* see as a NVA and Doc supporter from Audio-talk. Sadly for them not true as Steve is no one's shill, he is an honest man, which neither of those two can claim.
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#94 Re: "The Flatback Banned" OmniMet

Post by pre65 »

If Steve (or indeed anyone) finds NVA equipment to their liking then I'm happy for them. :)
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#95 Re: "The Flatback Banned" OmniMet

Post by Dr Bunsen Honeydew »

Like fuck you are, months and years of nip nip nip have proved what a liar you are. You are a slime bag who in this incident is acting as Robin to Gregs Batman. You are an insignificant apology for a human being - and yes I am reading your posts again.
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#96 Re: "The Flatback Banned" OmniMet

Post by pre65 »

Dr Bunsen Honeydew wrote: Fri Jun 30, 2017 12:14 pm Like fuck you are, months and years of nip nip nip have proved what a liar you are. You are a slime bag who in this incident is acting as Robin to Gregs Batman. You are an insignificant apology for a human being - and yes I am reading your posts again.
Richard, show me (and everyone else) where I have ever rubbished any product of yours.

The only one I've ever dissed was the cubes at Owston, and as you have said, that was not a good environment for them.

Please keep to facts rather than your ranting delusions.
The only thing necessary for the triumph of evil is for good men to do nothing.

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#97 Re: "The Flatback Banned" OmniMet

Post by Cressy Snr »

pre65 wrote: Fri Jun 30, 2017 10:12 am I'm not getting het up about Gregs comments (re my ears), and I hope Steve can take my comments in the same manner....
Steve (and his wife) accepted me (and Jean) into their home and were most hospitable. If I have betrayed that hospitality by my comments I'd be mortified. :(
Don't worry on that score Phil. It was lovely to see you and Jean and I hope she is on the mend.
The only thing I would take issue with is that your comment on uneven bass, doesn't mean what it looks like it means in print.
It was the fact that there was more bass on the right of the room than the left because of the way the speakers are positioned in the room, not that the bass was uneven and coloured in its response.
As you said, plans are afoot to rebuild the staircase wall and restore the room to its original state during the next year.

I think we can agree that the speakers sounded lovely. Now lovely might not necessarily be hi-fi in the strictest sense of the term but it is very easy to live with and listener fatigue is completely absent from the equation. That was the aim with both the normal Mets and wi these omni designs.
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#98 Re: "The Flatback Banned" OmniMet

Post by Cressy Snr »

Here's an interesting 6th octave spectrum analysis of the Flatties in-room, after I adjusted the feet, in order to raise the cabinets by around 1cm higher above the floor:

Image

The low bass has come up nicely and it is audible. However it is at the expense of a hump, centred around the line tuning freq (100Hz).
This hump has added a bit of punch to the bass and does not seem detrimental to the sound. Also, look at that classic BBC dip between 1K and 4K. The 6th octave response shows the in-room response in much more detail. Nevertheless IMO, that spectrogram looks fine to me, and the sound is excellent, natural and unforced.

The feedback I have had about this design is giving mixed messages. I have to say, I like the natural enjoyable sound and the sense of depth and the huge soundstage.
Some agree and others reckon they are "not bringing things forward enough" for their liking.

With this design I seem to have had in my head, the exact opposite of the sound of a Flat Earth, home PA speaker, and appear to have succeeded in realising that goal. That is good for me, anathema to others. Odd isn't it?
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#99 Re: "The Flatback Banned" OmniMet

Post by Cressy Snr »

The tweeter could do with a fixed LPad potential,divider just to level that shelf down between 1 and 15KHz, a tad.
If they are showing a slight brightness in my heavily furnished room, then they are going to be a bit relentless in a more sparsely furnished environment.

These are almost there.
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#100 Re: "The Flatback Banned" OmniMet

Post by chris661 »

Cressy Snr wrote: Fri Jul 21, 2017 10:51 pm
The feedback I have had about this design is giving mixed messages. I have to say, I like the natural enjoyable sound and the sense of depth and the huge soundstage.
Some agree and others reckon they are "not bringing things forward enough" for their liking.

With this design I seem to have had in my head, the exact opposite of the sound of a Flat Earth, home PA speaker, and appear to have succeeded in realising that goal. That is good for me, anathema to others. Odd isn't it?
Each to their own, Steve. I quite like the flat response approach, but I can appreciate why others might prefer something different.

I suspect some correlation between the dip 1-4kHz and those saying they don't bring things forward enough. Though if I remember correctly, the music you like tends to have quite a lot of content in that area, so having a slight curve to balance those things out isn't a bad thing.

Looks like the measurements roughly agree with what I was saying about the bass - if they were mine, I might want to knock the 100Hz area down a bit and try to bring up the very bottom end. That said, if you like the extra punch from the 100Hz rise, that's fine by me. They're your speakers playing your music in your room, and if that sounds good to you, I'm not going to argue.

Chris
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#101 Re: "The Flatback Banned" OmniMet

Post by Cressy Snr »

OK
By judicious use of an fixed LPad to keep the tweeter impedance the same, so as not to disturb the crossover, I have shelved down by 4dB, the region from 1K onwards. I have not measured anything yet as the ambient noise during the day buggers up my spectrogram measurements like you wouldn't believe. :roll:

But, everything has calmed down beautifully and I'm not "seeing" the tweeters now. Eva Cassidy sounds awesome and sits on the stairs once more, like she did when Paul B came round last year and I still had the big Mets.

The shelving down of the treble region has had the effect of bringing up the midrange a bit, giving more body to the sound, making the semi-omni presentation a bit less ethereal and more grounded. This omni business is a delicate balancing act; not straightforward, but then I like making things hard for myself... well I think I do. Maybe I should just conform and stop being one of those poncy, poofy, arty-farty, highly strung creative types. :geek:

I think the raised treble region was swamping the upper range output from the bass/mid driver, and affecting the direct to reflected sound ratio in a negative manner. Now the things seem to fill the room a bit more effectively; all learning that can be applied to the bigger ones on the other thread.

@Chris, I relented in the end and lowered the cabs again to flatten the 100Hz hump at the bottom. It was impressive for a day, but I became pissed off with it eventually. :)
The very bottom end will be dealt with by the big speakers I'm developing.
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#102 Re: "The Flatback Banned" OmniMet

Post by Cressy Snr »

Here's the in-room analysis with the 100Hz hump flattened, the port tuned lower and the tweeter range tilted down by virtue of the fixed L-Pad.

Image

I'm not going to realistically get it much better than this. A bit of bass coloration has disappeared, the very bottom has joined the rest of the bass range and the project sounds pleasingly musical.. The speed it had has not been lost, but there's a bit more finesse across the musical range, with more midrange subtlety.
Just shows you what can be got out of an efficient 6" pro midrange driver and a decent tweeter, if you are stupid enough to try :lol: :lol:
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#103 Re: "The Flatback Banned" OmniMet

Post by Cressy Snr »

chris661 wrote: Sat Jul 22, 2017 11:44 am
I suspect some correlation between the dip 1-4kHz and those saying they don't bring things forward enough. Though if I remember correctly, the music you like tends to have quite a lot of content in that area, so having a slight curve to balance those things out isn't a bad thing.

Chris
Oh yes, you've nailed it Chris.
I have discovered over the years that if like me, you are a 60s and 70s Stax/Motown/Atlantic soul/R&B fan and are designing speakers, then you absolutely NEED that dip, otherwise you are in for a miserable time with the vocals. It also makes massed voices, opera and orchestral strings sound sweet. I don't care that it is a departure from true flat response; for me it is a compromise worth making.

Also, and perhaps more importantly, the hearing damage I suffered after the middle-ear infection and Bell's Palsy, 18 months ago, has taken a very long time to resolve, and it has left me hypersensitive to peaky midband and upper treble energy. I think there is an offical name for this kind of acquired hypersensitivity; Mr I will know what it is, but this kind of speaker response set allows me to listen for long periods without fatigue, to the music I love.
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#104 Re: "The Flatback Banned" OmniMet

Post by Cressy Snr »

More developments today with the flatties:
Image

Notice the slight forward tilt of the top surface, with the main driver.
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#105 Re: "The Flatback Banned" OmniMet

Post by Cressy Snr »

Here is a cross-section of the cabinet to scale, showing the tilt modification:
Image
Rear legs have simply been made longer than the front, to tilt the top about 5 degrees off the horizontal.
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