Big coaxial with RCF CX12N251

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#141
Thank you for clarification about bass. Your(s- i include Rallyfinnen) approach makes sense.
I like to model and know approx final Q of loudspeaker beforehand. But i admit it can be seen as OCD, as reality rules anyway.

I wondered about boundary distance relative to your push push arrangement but you answered without having to ask:
low end will see boundary coupling.

Ps: whish you'll recover fast and nice Juhazi.

Edit: Rallyfinen, yes the hump. Could be done passively at line level: since i play with LT i keep on telling me the overall shape is the same that can be achieved through the use of passive eq Pultec Eq1p low band circuitry ( using boost and cut at same time it gives the same curve's shape for LT with native driver/box 's Q in the 1.1-1.2 range). Driven through a pro DAC ( +24dbu) and using a power buffer ( like an F-4) and some line level buffer stage for impedance matching purpose, you could drive sensitve loudspeakers ( or couple or groups) without voltage gain involved in the chain and no fear of distortion before amplifier.
 
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#142
Juhazi said:
Speaker B's inner box was glued today. I had time to fit some supporting studs too. 4 hours work, all big plates were cut beforehand. Volume of the box for two SLS-12 is roughly 50 liters. I could get 15-20L more by making cutouts to sides.

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I'll have to keep an eye on this thread! I am [very slowly] building a similar speaker design. I'm using a 12" coaxial, plus 2 woofer/ subwoofers. The difference is that instead of dipole, I'm treating each low frequency driver like an individual subwoofer, and using delays between them to flatten out in room response.

I have opted for a more "monolighic" design. Like a square column 16x16x54".
 
#143
^This speaker will not be dipole! Woofers are in same phase/polarity, but opposing and thus will have force cancellation. They will play below 300Hz so they behave like a true omnipole. The mid on the frontside will make some cancellation with the sound coming from the backside, depending on the xo F and steepness. Front wall will reflect and reinforce the low bass and makes placement of this kind of speaker a bit tricky.
 
#144
Juhazi:

I guess I missed that. Was skimming through the thread....

Then I'm curious about the choice to take this approach! The way to get guarantee results is to use independent drivers + DSP delays, because then speaker placement is irrelevant. But as it is, I wonder if the location where the low frequency drivers need to be positioned will result in a standard stereo speaker arrangement?

I'm interested to see measurements! Do you have a quantifiable result you are hoping to achieve? Or are you happy if it looks good and sounds better than what you currently have?
 
#145
Actually I don't know what to expect exactly. Basically omni woofers and 12" mid with horn tweeter will (should) give DI like JBL M2 and similar. In the opening posts you can see some speakers that made me go this way. At least I hope to learn something, and doing mistakes is the best way!

https://www.erinsaudiocorner.com/loudspeakers/jbl_m2/

I hope to start taking measurements and setting xo/dsp in April!
 
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#146
Sunday morning here, -10C and clear sky!

Greetings Rallyfinnen and krivium,

Openings to side panels should not introduce port noise, because air flow is minimal, all chambers are closed. Helmholz resonance could be an issue, we will see... Here my pic of the statue of prof. Helmholz in Berlin

helmholz statue.jpg


My epilepsy has been well in control with medication. I just visited neurology clinic and next visit wil be in August and I hope to get my driver's licence back then! My knee joint is healing well too, but I must rest it often. I have hurt it many times since the first bad injury in '75... so it will never be totally OK.
 
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#150
You seem to have a lot of time and experience.
Have you thought about turning this coaxial into a multi entry horn to make a full range driver?
It could be a big horn with a cylinder in the back to enclose the woofer, like a big field coil driver.
It would not look like a typical meh.
 
#153
^I guess that you are mixing me with some other person. I have never had any horns, big or small than this coaxial. However a friend had huge diy MEH 3-ways (900mm), and I didn¨t like the soundstage of them - almost like wearing headphones.

Actually I detached the horn last weekend (and it's aluminium, not plastic like datasheet says) to see how easy it would be to make a minimal throat adapter so that the cone acts as horn. I forgot to take pics, but the coil former is extruding so much that it's impossible to make transition smooth. This 12" cone has 14mm travel and thus would introduce IMD for the tweeter (CD). The benefit of a fixed horn is avoiding IMD and response variations per cone position, and this is the thing that made me to choose this model, this time.
 
#155
Juhazi said:
This 12" cone has 14mm travel and thus would introduce IMD for the tweeter (CD). The benefit of a fixed horn is avoiding IMD and response variations per cone position, and this is the thing that made me to choose this model, this time.
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This is a quite common misthinking with large cones. Coaxials have part of horn that is not moving and in home use cone movement is small. It is especially small when there is separate woofer. More like under 1mm than 14mm.
 
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