[JLM]

I use 8 inch Fostex F200A drivers (90 dB/w/m at 8 ohms, fs=30 Hz, Qts = 0.32).  The maximum input power is 27 watts (rated) and 80 watts (music).  My amplification comes from 40 watt Channel Island Audio VMB-1 monoblocks (chip amps).

My first question is:  What do you think is meant by "rated" versus "music" power?

My next question is:  What should the minimum ideal power rating of the amp be?


Note that the drivers are in transmission line cabinets, in a 2,200 cubic foot room where I do critical listening nearfield at "reasonable" spls (typically below 90 dB).  OTOH I am a big believer in having plenty of power for dynamic headroom and to provide a commanding grip on the drivers.

Also note that I've replaced the vendor supplied baffle step/zobel with DEQ and honestly may be pushing more bass/treble boost than I should.  As a result the monoblocks seem to have lost some of that commanding grip, however I'm also of the opinion that cabinet, internal circuitry, even the room all provide a form of EQ.

My last question is:  Do the various forms of EQ add to the capacity of the driver to accept power?

TIA

[chlorofille]

  My next question is:  What should the minimum ideal power rating of the amp be?   TIA

  The minimum ideal power for your listening session would probably be about 10 watts since you're not needing >90dB SPLs nearfield. Your current amplifier is more than sufficient to drive the speakers far louder than you actually need. 

  My last question is:  Do the various forms of EQ add to the capacity of the driver to accept power?  TIA

  This will in fact reduce the power handling of your Fostex's as the cone excursion will be increased upon bass boost EQ'ing. Basically for the same SPL(90dB), the cone will be moving a great deal more and distorting.  IMO I don't see the point of using a extended range driver with an active crossover since it basically defeats the purpose of an extended range driver. From a purist's point of view, Zobel + baffle step would be ideal. 

[roymail]

I love the sound of the LM3886 amps, the texture and the way they grip the drivers.  Although they have their limits, they are amazing within those parameters.  Otherwise, you may want to give the Class D Audio amps a try, especially the SDS series.

I've got a feeling that your current setup sounds very nice just the way it is... but I understand what you're saying.   

[rjbond3rd]

Wow, 2,200 square feet is pretty huge.  It must feel like a warehouse.

[Mariusz]

If I had that space-
PHY Drivers in open baffle and one of John Kalinowski's 31.5 inch subs.

As to power requirements - quality 20wpc with matching preamp should be more then enough.

(no EQ for me either)


Cheers
Mariusz

[JLM]

Oops, I meant 2,200 cu. ft.  The room is 8 ft x 13 ft x 21 ft.

Thanks for the feedback.  I had the same idea (that pushing low frequency EQ would actually further limit how much power the drivers could handle).  Since posting I've have a couple of instances where furnishings in the room have exhibited midrange vibrations from sub-sonics coming from the speakers, so I really need to back off the low frequency EQ. (I had 6 cu. ft. 3-way transmission lines years ago that were rated 114 dB at 17 Hz, those were total beasts, still this impresses me for a driver rated out to 20,000 Hz.)

And thanks Roymail, it does sound pretty good IMO.

There has been much discussed even published regarding dynamic range and how high instant peak sound pressure levels can reach.  But I'm trying to achieve dynamic peaks of at least 105 dB (a fairly popular number) in my nearfield setting.  That would require about 30 watts a side for a pair of 90 dB/w/m speakers.

BTW DEQ sounds far better than the baffle step/zobel circuit (the presentation just makes more sense when you can achieve flat in-room response).  Even Bob Brines (the creator of my speakers) uses DEQ too, even though he sells speakers with the baffle step/zobel circuit.

[rjbond3rd]

Hi JLM, have you considered front-loaded horns?  Those would be the ultimate in dynamic range.  They just "breathe" and in my experience, nothing else even comes close.

Of course they can be loaded with a single driver.  http://www.azurahorn.com/pages/David%20Wong%20PM4a_JPG.htm

The difference between FLH and regular single driver is as great as single driver is from multi-way.  And actually not terribly expensive!

[JLM]

Thanks for looking, yes I thought about lots of things when we were building the house 5 years ago. 

I've heard similar horns, but the common complaint is that they never integrate well with the required bass units.

Front loaded horns are the ultimate, but to go as deep as these transmission lines would have required that I give up our only storage room in the house (and pour lots of concrete to achieve the required size/stiffness).

And how could I sit nearfield with horns that big?   

[rjbond3rd]

Hi JLM,

Oh you  can totally listen to those horns near-field, if nearfield means 6 feet?  I've never heard the complaint that horns don't integrate with the bass units.  In fact, integration is a snap around 200Hz (those horns have a cutoff of 140-160).  For me, "hard to integrate" is when you're trying to blend in a sub at 60-120Hz and the room modes are in the same range.  That alone made me give up on subs completely.

[JLM]

I'm not interested in speakers that don't reach the bottom 3 octaves without help.