Cressy's Banned Omniset

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Chunk McDaniel
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Re: Cressy's Banned Omniset

Unread post by Chunk McDaniel » Mon Sep 25, 2017 11:39 pm

Glad you got it sorted Steve. Sometimes these things are staring us in the face and we can't see them.

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Hemmo1969
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Re: Cressy's Banned Omniset

Unread post by Hemmo1969 » Tue Sep 26, 2017 11:54 am

Would be good to here them again fella now you have 'tweaked' the tweeter.
I did think something was amiss when you were chuntering "f'kin background music' to yourself :) Glad it led to you ruminating a path forward AND a solution.
Good to meet you on Sunday.

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SteveTheShadow
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Re: Cressy's Banned Omniset

Unread post by SteveTheShadow » Tue Sep 26, 2017 2:03 pm

Hemmo1969 wrote:
Tue Sep 26, 2017 11:54 am
Would be good to here them again fella now you have 'tweaked' the tweeter.
I did think something was amiss when you were chuntering "f'kin background music' to yourself :) Glad it led to you ruminating a path forward AND a solution.
Good to meet you on Sunday.
Yes, good to meet you too.
I was not best pleased with the speaker's performance on Sunday. When that happens I shut down and go into an intense problem solving mode, to the exclusion of all and everyone else, including such social norms as not being a miserable bastard in public :naughty:
I went and found out the other Chris, plus Colin and told them straight up, that IMO the sound was fooking shite and what did they think.
They didn't think it was as bad as I was making out, but both were pretty constructive about the performance and were in agreement with me about the dismal lack of lower treble tone and space in the sound.

My view is that you have to be pretty ruthless in your analysis of the sound and need to be prepared to say so up front, without trying to make excuses, when something isn't working as you think it should be working. Granted, speakers are very much a personal thing, but nevertheless, there is a minimum standard of performance that should be taken as read, and in my opinion, on that day, in that environment, the damned things were not meeting that minimum and, as I said in the previous post I made, it simply wasn't good enough.

There are ways of telling people and on Sunday, exactly the right methods of "telling" were employed by both Chris and Colin, and constructive ideas were bounced around between us as to what could be done about the problems with the speakers. The result was that I eventually discovered that the crossover was way out, due to human error ie misreading the tweeter impedance spec.
The methods were correct but I had been working from the wrong base. :oops:

These semi-omnis are a mash up of ideas from Roy Allison, Richard and Martin J King. It is a bit "outside the box" to be using such disparate ideas as semi-omni operation and quarter wave bass loading, so there is not much available in terms of help if problems are encountered; you are a bit out on a limb with stuff like this, but I enjoy being outside the mainstream, though it can cause a hell of a lot of grief and you need to be highly self critical of very step, whilst at the same time, believing absolutely in what you are doing; a difficult, often potentially explosive mixture.

It was great however on the day to hear the speakers in that dem room. Listening past the obvious top end problem, it was good to hear the against-the-wall, quarter-wave loaded, down-firing bass policy, demonstrating a quick, clean, even, performance at the bottom end, and the uncoloured vocal performance was gratifying. Now that the correct tweeter cap value is installed, the performance further up the range matches the rest of the frequency spectrum.

I certainly have no qualms anymore about their performance. :)
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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Dr Bunsen Honeydew
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Re: Cressy's Banned Omniset

Unread post by Dr Bunsen Honeydew » Tue Sep 26, 2017 2:12 pm

I am also at fault I should have listened more closely but I made a presumption that they were going to be Cube like as the first few bars told me and I got caught up in a conversation so didn't give them the attention they deserved, sorry rude of me.

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SteveTheShadow
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Re: Cressy's Banned Omniset

Unread post by SteveTheShadow » Tue Sep 26, 2017 2:20 pm

Dr Bunsen Honeydew wrote:
Tue Sep 26, 2017 2:12 pm
I am also at fault I should have listened more closely but I made a presumption that they were going to Cube like as the first few bars told me and I got caught up in a conversation so didn't give them the attention they deserved, sorry rude of me.
Not your fault Richard, as I said earlier, the fact that 70% of the audience switched off and did something else was not down to rudeness, but down to the speakers not really doing anything to make anyone take notice. IOW they were background music; not necessarily a bad thing, but hardly hi-fi :lol:
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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Re: Cressy's Banned Omniset

Unread post by SteveTheShadow » Tue Sep 26, 2017 7:01 pm

image.png
image.png (200.74 KiB) Viewed 671 times
Above is a third octave, pink noise, in-room spectrograph of the speaker, with the correct cap value, taken this afternoon:
That'll do very nicely, thank you. 8-)
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: Cressy's Banned Omniset

Unread post by karatestu » Tue Sep 26, 2017 7:44 pm

Very good Steve. What frequency did you crossover ?
Naim, Linn & Harbeth fanboy

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SteveTheShadow
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Re: Cressy's Banned Omniset

Unread post by SteveTheShadow » Tue Sep 26, 2017 8:26 pm

3.5 KHz.

2x5.6uF in || to tweeter. Bass/mid is running wide open.
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".

Simon Hickie
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Re: Cressy's Banned Omniset

Unread post by Simon Hickie » Tue Sep 26, 2017 9:21 pm

I make that about 3db down at 3.5khz into a 4 ohm load. Does that sound about right?
“The reasonable man adapts himself to the world: the unreasonable one persists in trying to adapt the world to himself. Therefore all progress depends on the unreasonable man.” George Bernard Shaw.

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SteveTheShadow
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Re: Cressy's Banned Omniset

Unread post by SteveTheShadow » Tue Sep 26, 2017 9:51 pm

Yep, that's about the size of it.
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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