[drcruz]

Mike,

I'm SO happy w/ my pair of Force subs (prefer the old look by the way - but you can't please everyone as they say, no biggy ) I have to ask, is ACI every going to make a >90 db High Sensitive speaker w/ a Flat Impedance response that never dips below 6 Ohms?

As for the Force subs my only regret is that I didn't go for a pair of old Titans instead - I've changed my audio goals and the Titans would have been better for me. My loss  - but the Forces are still GREAT for the money.

Just curious...

Thanks in Advance

[EProvenzano]

RAW LXII would be another option.

[Mike Dzurko]

I'm guessing the reason is because of a desire to use with specific amplifiers? 

[konut]

Visaton B200, now.

[JoshK]

This seems to be a often requested product, monitors that are small, moderate efficiency and tame impedance curve.  However, we must not forget Hoffman's iron law.  I will quote a paragraph from a HT mag review that said it succintly:

Hoffman's Iron Law, described by Henry Kloss in the mid-1950s and later turned into an exact mathematical formula by engineers Thiele and Small, governs the behavior of woofers. Essentially, it says that a woofer's efficiency is proportional to the volume of its cabinet and the cube of the lowest frequency it can produce before losing relative level (aka the cutoff frequency). Take, for example, a woofer whose response is flat down to 40 hertz in a 2-cubic-foot enclosure. To make its response flat down to 20 Hz, you must either increase the cabinet volume by eight times (to 16 cubic feet) or use eight times the amount of amplifier power to achieve the same listening volume. Given these requirements, you can see how difficult it can be to get respectable low-frequency response from small "full-range" speakers.

link

Those here who have read some of Dave Ellis's threads on subs and 3 ways will be reminded of the 'triangle' he likes to refer to.  With apologies to Dave for murdering his words, I'll paraphrase.  If you have a triangle with Small Size, High Efficiency, Extends Deep in the corners, choose any two you won't get the third.  That is what Hoffman's iron law says. 

So what does this mean?  It means that you have to give up a few octaves on bottom at minimum to acheive reasonably high efficiency with a small monitor, or you need to accept a very large speaker in your room. 

[Mike Dzurko]

90+dB/6 ohm minimum allows the use of lower powered amplifiers....in my case specifically lower powered tube amplifiers (say in the range of 20-50 wpc).

Thanks for sharing, but heck, we've already got that covered . . .the Sapphire XLs absolutely sing with a good 30-50 watts of tube power. Last two CES used the Primaluna 35w/channel ourselves with excellent results. A number of customers use various tube amps in this power range with the XLs. For even greater dynamics and larger spaces consider passive hi-pass and using sub(s) for the bottom end.

[Mike Dzurko]

This seems to be a often requested product, monitors that are small, moderate efficiency and tame impedance curve.  However, we must not forget Hoffman's iron law.  I will quote a paragraph from a HT mag review that said it succintly:

Hoffman's Iron Law, described by Henry Kloss in the mid-1950s and later turned into an exact mathematical formula by engineers Thiele and Small, governs the behavior of woofers. Essentially, it says that a woofer's efficiency is proportional to the volume of its cabinet and the cube of the lowest frequency it can produce before losing relative level (aka the cutoff frequency). Take, for example, a woofer whose response is flat down to 40 hertz in a 2-cubic-foot enclosure. To make its response flat down to 20 Hz, you must either increase the cabinet volume by eight times (to 16 cubic feet) or use eight times the amount of amplifier power to achieve the same listening volume. Given these requirements, you can see how difficult it can be to get respectable low-frequency response from small "full-range" speakers.

link

Those here who have read some of Dave Ellis's threads on subs and 3 ways will be reminded of the 'triangle' he likes to refer to.  With apologies to Dave for murdering his words, I'll paraphrase.  If you have a triangle with Small Size, High Efficiency, Extends Deep in the corners, choose any two you won't get the third.  That is what Hoffman's iron law says. 

So what does this mean?  It means that you have to give up a few octaves on bottom at minimum to acheive reasonably high efficiency with a small monitor, or you need to accept a very large speaker in your room. 

Josh:

Very well said. However I don't think the OP said anything about size. So it is possible for example to build a larger two way box with a larger woofer and gain efficiency and keep the same bandwidth. However, that larger driver will certainly sound different in the midrange than a smaller driver will . . .  and IF we were able to keep the quality level of drivers/cabinet constant, the cost would have to go up as well. No free lunch.

Regarding impedance, it isn't just the nominal load and the min. It is the reactive component, the phase angle as well. For example, two summers ago we were doing a demo with the Sapphire XL where a factory rep of a SET tube amp was present. He proclaimed that there was no way it would drive the XLs because "mini monitors all present too difficult a load". He had a pretty tough time a few minutes latter when the two were happily playing together. I'm not saying it would blast us out of the room, but at moderate volume it was pretty respectable and he was shocked.

[Mike Dzurko]

Mike, are you at CES this year? If so what hotel and room?

Nope, decided to do RMAF yearly instead . . .

[opnly bafld]

Nope, decided to do RMAF yearly instead . . .

And all of us that attended RMAF are glad that you did.

Lin

[Mike Dzurko]

Nope, decided to do RMAF yearly instead . . .

And all of us that attended RMAF are glad that you did.

Lin

Thanks Lin    I really enjoyed RMAF and meeting so many fun folks (like you) . We'll be back this year for sure!