"The Flatback Banned" OmniMet

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Ant
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#121 Re: "The Flatback Banned" OmniMet

Post by Ant »

Id have thought it would be to do with the reflection off the ceiling coming back down, when sat down its around where you are, and when stood up your ears are higher so you are off axis from both the forward firing twatter and the reflection off the ceiling thats filling in too?
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Cressy Snr
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#122 Re: "The Flatback Banned" OmniMet

Post by Cressy Snr »

IslandPink wrote: Fri Sep 29, 2017 4:41 pm I think you're doing exactly what you should - learning what you want and how to engineer it - at the end of the day it's you that uses that system. Also with a lot of the music you have from the 60's it'd be too harsh on many flat-response or up-tilted speakers that others like.

Well thanks for the vote of confidence Mark :)
The problem is that I think that I have, over the years, let my enthusiasm for 60s pop music colour my judgement. After Huddersfield, it really brought it home to me more than ever before, just how much information I have been losing from the picture, because of my single-minded crusade about taming these records.

The crusade I have been on is not about the closest approach to the original recording, but making everything sound nice, no matter what the quality of the source material. And do you know what? Actually listening to some of my 60s stuff, with the omnis as they are now, is not really that bad. Chris educated me on how they used compression, eq, why and what to listen out for - very interesting conversation.

I can say to myself "yes, that was mixed for AM radio" but I am not wanting to turn it off; turn it down a bit maybe, but it doesn't have me fleeing the room. In fact it is quite educational to listen to how these old recordings have been manipulated in the studio for maximum impact. You might think that this lot would make for an intellectual listening experience, and I would be somehow missing out on the music, but it is quite the opposite. The missus has been singing along a lot more and monkey bones have been exercised with plenty of 60s dance music.

Boogie factor on some of my soul and Motown stuff is actually greatly enhanced by the correct reproduction of the famous "Motown sizzle" in the upper mids, that Berry Gordy used to insist was used on the singles to make them stand out on the radio. Motown albums don't have this, so presumably he thought that album buyers were a bit more sophisticated than the single buyers.
One thing from your comments above though - how could an Omni ( I mean if it has an up-firing mid-woofer ) have a stable polar response vertically ? If the woofer's treble is being lost by pointing it upwards, doesn't that mean you hear more of that treble if you stand up, and less if you sit down ? Seems like it would be an inevitable result of the design.
Ah yeah but no but, you forget the forward firing tweeter.
Stand up - fwd firing tweeter loses treble, up firing driver gains treble
Sit down - up firing driver loses treble, fwd firing tweeter gains treble.

Match the roll off/roll in rates and one complements the other, as you move around. Sound stays the same wherever you are (within reason of course) It's one of those things that is only achievable by listening and empirical experimentation.
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#123 Re: "The Flatback Banned" OmniMet

Post by Cressy Snr »

Hmm...
Jeff Cascaro, Love and Blues in the City, solo piano intro to "A Taste of Honey"
What's that on the piano? Distortion?
No, it's the drummer's snare wires vibrating in sympathy with the piano.
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#124 Re: "The Flatback Banned" OmniMet

Post by Cressy Snr »

I now need somebody to come over and have a listen.
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#125 Re: "The Flatback Banned" OmniMet

Post by simon »

I'd love to Steve, but I'm out of the country at the moment. Maybe when I'm back?
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#126 Re: "The Flatback Banned" OmniMet

Post by Cressy Snr »

simon wrote: Sat Sep 30, 2017 9:44 pm I'd love to Steve, but I'm out of the country at the moment. Maybe when I'm back?
Yes, that would be good.
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#127 Re: "The Flatback Banned" OmniMet

Post by Cressy Snr »

I have a cunning plan for future builds of these speakers.
I'll fit a two position switch labelled, "Owston" and "What a relief" along with the associated caps and resistors needed for the required effect.

That ought to do it!

You know it makes sense! :D :D :lol: :mrgreen:
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#128 Re: "The Flatback Banned" OmniMet

Post by IslandPink »

Hooray - the return of the tone control :D
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#129 Re: "The Flatback Banned" OmniMet

Post by Cressy Snr »

Well Mark,

I've thrown the "What a Relief!" switch.

The "WOW, what a lotta harmonics! experiment is over. Sod that! I have stood it for a week, and that's long enough it was all very nice in a hi-fi sort of way, but I want to listen to music, not end up with bleeding ears.

All it needed was the removal of the white tack ring from the main driver. The crossover didn't need touching, so it is back as it was before Huddersfield. Taking out the white tack ring was the trick that restored the harmonics to cymbals etc, I overcooked it by also feeding more upper midrange energy to the tweeter. The resulting sound was very impressive, but ultimately fatiguing.
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#130 Re: "The Flatback Banned" OmniMet

Post by Cressy Snr »

Blu-tac rings installed instead of white tack, and I'm back to where I was, pre Huddersfield.

Balance is now even, once more and the music speaks.

Was watching this video of Art Dudley of Stereophile magazine, yesterday with our Ant.




Art was discussing his speakers, vintage turntables and the art of reviewing. At a couple of points he was pictured sitting, like Ronnie Corbett, in a chair that looked way too big for him, talking about reviewing.
Much sense came from him, he's a top guy. I took his chairborne advice and am now happy again.
Odd how you can make a change, be deleriously happy......then it wears off.

I've decided that if my idea of good sound is not what most people's is then so be it. I value long term listenability it seems.

I've found a lot of omni discussion on DIYAudio and it is veeeeery interesting, so along with these crazies and the users of
NVA Cubes and Shahinian speakers in the UK, I'm certainly not on my own in liking the omni presentation.
Omnis and semis like, mine play music in real rooms like nothing else. For me, they are unsurpassed.
I'm nearly 60 and it's time to stop people pleasing and please myself. :)
This vacillating between one viewpoint and another HAS to stop ferchrissakes!
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#131 Re: "The Flatback Banned" OmniMet

Post by IslandPink »

Cressy Snr wrote: Tue Oct 03, 2017 3:42 pm This vacillating between one viewpoint and another HAS to stop ferchrissakes!
But what would we watch while eating our popcorn, Steve ?
Anyway, I thought the new speakers were going to have a built-in vacillator ?
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#132 Re: "The Flatback Banned" OmniMet

Post by Cressy Snr »

They do, I simply simply strapped out one of the crossover caps. It's a simple matter to put an Owston switch on the back.
Better a vacillator switch than being a tormented, erratic nutter, cowering in my ill-lit, unheated, deathwatch beetle infested garret. :confused2:

I have a bigger omni to get on with after the DHT amp. That too will have an Owston switch to its tweeter.
Everybody should fit one. If Tannoy can fit fancy, ornate brass Owston switches to their big dual concentric models, then why not us mortals. It's the way forward. :wink:
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#133 Re: "The Flatback Banned" OmniMet

Post by Cressy Snr »

OK, further developments.
I've taken out all the damping from the cabs, every last vestige.
A good result so far in terms of inner illumination, harmonic detail, quality of upper midrange tone and "liveness"
Bass boom is conspicuous by its absence.
So again, what I've written in the previous few posts is, as is par for the course at the moment, complete utter bollocks.
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#134 Re: "The Flatback Banned" OmniMet

Post by Cressy Snr »

So what we have now is a semi-omni tapered MLTL, with zero damping in the line. This works.

I've treated zero damping inside speaker boxes with scepticism, since I started building them a long time ago.
In the early eighties, Jimmy Hughes used to talk about the benefits of removing damping, but I never tried it.

More recently,Richard Dunn has argued for zero damping and steel lining wood cabinets and has suffered derision and scorn from certain sections of he industry.

My cabs are not steel lined, but even so, the sound has benefitted, in terms of speed, dynamics and tone by the simple expedient of taking out the dacron fibre from inside the quarter wave line. It is not horn speed and whipcrack bang, but there is a definite horn like quality to the sound, and in a good, rather than a bad way.

Now Scott has argued with several well known designers about what is the exact nature of an expanding line, folded or otherwise. He reckons it is a closed off horn (except for the small port area at the wide end) and is also a variation of a tapped horn, due to the positioning of the driver at a distance away from the throat.

Treat it like a tapped expandng horn, with a restricted exit, ie don't damp it and make sure the construction keeps panel resonances away from the midrange and you seem to get a fast-paced, dynamic, powerful and efficient system.

From what I am hearing from the undamped system I am with Scott on this tapped horn way of looking at an expanding quarter wave line.
Last edited by Cressy Snr on Tue Oct 03, 2017 7:55 pm, edited 2 times in total.
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#135 Re: "The Flatback Banned" OmniMet

Post by IslandPink »

Good work !
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