When and why did the typical floorstanding speaker lose the midrange driver?

[drrdf]

OK: perhaps only a few of us have ever considered it or actually done it.

[drrdf]

OK it is a value judgement; but I don't think most people would want to extend to the extreme of 2 Hz, even if it were practical to do so.

You seem to miss the issue of proper sealing. Whether in a cavity wall or not proper air-tight sealing is necessary between the baffle board and inner and outer layers, and the drive units must not vent into the wall cavity. They must be able to vent into the outside atmosphere only. It is a type of installation only appropriate for larger rooms (not thus for the modern dwarf houses). Provided any windows are properly sealed and that the room is sufficiently large the issues you cite are so small as to be insignificant. As with all things H-Fi (and food) the proof of the pudding is in the eating. If you had heard a properly-executed example of this type of installation you would understand just how good it can be, using the best available LF drive units.

[Pharos]

I agree about 2Hz.

It wasn't apparent to me whether or not you were referring to using the cavity as an enclosure.
If the rear of the driver is exposed (right through the cavity) tyo the external environment that opens up a whole new can of worms.

I also agree about the other issues at least tending towards insignificance.

[majex45]

I believe the switch to two drivers was started by the introdoction of ports to the cabinet.
This meant a driver could reproduce the mids and then resonate with the port for the lower frequencies.
Two drivers equals lower cost.
This was a follow-on from the ABR type of enclosure where they used a speaker less voice coil etc to act as a damped port.

[graham67]

Pretty much like F1 which went from Big 3.5 V8 engines to 1.6 hybrids which are if anything even faster.

Hi Robbie, at the risk of mangling my metaphors, modern F1 cars better the old ones in most objective areas. However, most fans would consider that the big old V8 bangers sound much better and elicit an emotional reaction that eludes the current crop 😉.

But i agree, it is good to have a choice as not everyone wants to live in a recording studio. ☺

[Barry]

Ronald,

How much output (in Phons) at 15Hz did your designs generate and how much electrical power is required?

[drrdf]

Ronald,

How much output (in Phons) at 15Hz did your designs generate and how much electrical power is required?

Hi Barry, I used around a normal maximum of 40 W rms per channel (from an 80 W rms per channel amplifier), producing an output at 20 Hz of around 100 Phons. You will gather that I like my music rather LOUD (much to my wife's displeasure). But that is mainly to cover the large dynamic range particularly of the Romantic period classical music which I enjoy the most, like Mahler; it is only on peak volume passages with much bass content that the music is this loud. I try to reproduce music at the same level and with the same dynamic range which it had originally. I admit that you do really need a relatively large detached house to do this. In modern dwarf houses, all crammed in too close to one another and with cupboards instead of rooms, it is quite inappropriate. Also with the dumb announcers on radio these days who get right up close to a relatively wide-range microphone and thus produce a distorted excessive bass timbre to their voice, that can be a continuous problem.

As I observed earlier G A Briggs of Wharfedale with his corner brick reflex, which had a vent size of 9 inches X 6 inches and a 15 inch diameter bass driver was able to lower the cone resonance down to 18 Hz. That was pretty good and he claimed that at 18 Hz with only 2 W rms drive into the unit a lighted match was extinguished at the vent. I also designed two modified reflex cabinets with more modern drive units and they were excellent and achieved better than this down to 16 Hz. (I prefer KEF drive units and still have several new vintage ones never used in their original packing, left over from when I was experimenting and building enclosures. I am now getting rather too old now for that sort of thing!!) The problem of course was the size of these units. Eventually my wife insisted that I demolish them, sadly. I now have to make do with much smaller units, which I also built, and the infra-base performance of these is of course not as good, but still better than most modern commercially-available units. (I am hoping soon to build some new units to a later design which I had configured, and never yet built, because I have a house in another European country with a large basement, which thus has lots of available room, so that the wife cannot complain so much! She probably will though!)

[Barry]

100 Phon is about 27dB above the threshold of hearing at 20Hz. I'm surprised it only requires 40W to achieve that volume level.

How big is your listening room? Mine is 75m³, so I calculate that for adiabatic expansion/compression to achieve the above pressure level change, the 'speaker' would have to move about 1m³ of air during each half cycle. I don't understand how that can be done with drivers of modest size.

[Pharos]

From drrdf;

"Also with the dumb announcers on radio these days who get right up close to a relatively wide-range microphone and thus produce a distorted excessive bass timbre to their voice, that can be a continuous problem."

The major factors which to me make radio virtually unlistenable are; 1 firstly, as you state, 2 the inane rubbish being spoken, and 3 the poor articulation/enunciation, the latter of course serving to obscure the second one; if rubbish is spoken well, it readily exposes itself for what it is.

[bumpy]

I believe the switch to two drivers was started by the introdoction of ports to the cabinet.
This meant a driver could reproduce the mids and then resonate with the port for the lower frequencies.
Two drivers equals lower cost.
This was a follow-on from the ABR type of enclosure where they used a speaker less voice coil etc to act as a damped port.

Unless I have it all wrong, the internal space in the cabinet is a Helmholtz resonator. any bass that is allowed out is essentially a one note honk. Deep and supportive of the mid band but not very musical.