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I’m new to this outstanding website and I found it has really educational value and antimoronizating information

I’m still in the world of direct radiators and I’m looking for the ultimate midbass channel solution. At this time it’s still impossible to build a horn of this size so my purpose is to find the next most good sounding solution. Some time ago I found very appropriate driver for upperbass reproduction – ScanSpeak 18W/8535. It has smaller magnet system (and little lower efficiency) compared to 8545. The cone material is the same as the famous 25W/8565-00 bass drivers and it has very good tone up to 600-650Hz. But then I read this:

Romy  the Cat wrote:

Ironically, among all enclosures and topologies that I have heard I found that a properly done bass-reflex enclosures can do the  “the melody range” quite adequately. What, the ported speakers? Are you out of your mind, Romy? This what you are proposing after the years of bitching about the “ported sound”? Yes, I do. Here is what I mean…. If a port is properly implemented then the port might do a phenomenally good upper-bass, almost as good as a “horn-loaded” upper-bass horn. The problem is that NO ONE uses the ported design properly. If do not let the ported design to go all the way down and to cut off the channel very slightly lower then the port begin to EQ the bass then it is possible to get a very-very good Sound using the bass-reflex enclosure. Paradoxically the driver in this case should be not really “ported” and an extra one or two LF channels would be mandatory for the lower octaves but with all those incontinences we gain “quality” of sound… using a port. A typical cut off of a bass-reflex enclosure in order to work properly should be somewhere around 110Hz-180 Hz and it done so then the “ported sound” does not manifest itself at all. Quite in contrary, the properly done bass-reflex might be very live, very dynamic and very musical.

It’s a quite interesting idea and I’m going to try this type of midbass loading very soon with SS 18W/8531 driver I don’t own yet.

Romy the Cat wrote:

The only one problem that I can see with properly done port channels that they are effective only in a VERY narrow bandwidth. Bring frequencies too low and the noise form the port compromises the entire “melody range”. Bring it too high that the driver being to sound like an open baffle….

I absolute agree with that statement! I made experimental enclosure for SS 18W/8545 tuned to 36Hz line high passed at 140Hz first order. The problem is that it sounded like open baffle even filtered at 300Hz…. And still it’d just one octave operation bandwith. If I lower the upper frequency point to 220Hz this effect evaporate but effective radiation is only 140-220Hz and it sounds like a little peak in the frequency response.

But later you said

Romy  the Cat wrote:

“Commandments of Mandatory Middbas Compliance”: 1) A middbas driver shell handle at least one octave below it lower cut off frequency 2) A dipoleness shell not be used anywhere near a middbas channel The next candidate for middbas reproduction would be all versions of the box-reflex design.  Everything in ported sound is wonderful accept the fact that the ported enclosures kill all sound under 700Hz -800Hz. The third rule of “Commandments of Mandatory Middbas Compliance” said: 3) You shell run away from a speaker if you see a port

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