Need the best amp

[PENG]

We had been through with this before. The claim that the impedance an amp sees could be less than the dc resistance of a speaker can be confusing if not misleading. An LC circuit at resonance may in theory have impedance of either zero or infinite depending on how they are connected, so in that sense it can in fact be less than the LC circuit's own dc resistance but the overall impedance of the speaker presented to the amp will not be less than the overall DC resistance of the speaker. So again, I am not clear what TLSG is saying other than it can be misleading. I know I may be adding to the confusion right here but hopefully not so, for those who have a background in EE principles.

 

[Send Margaritas]

Out of curiousity, what do the Legacy Focus HDs run for, street price? The originals, and the HDs look like beasts.

Even with two massive subs, my brain always tricks my ears into liking speakers with a bunch of substantial drivers like those.

Part of me would like to DIY a pair, as a bi-amped design using two 3-way cross-overs and some TC sounds 12's. (Hey, not all of our tastes are the same!)

I'd love to go demo some of those, or the HDs, in the Chicago area. Anybody know where?

...I feel the need to another 20 amp circuit already....

 

[Irvrobinson]

Out of curiousity, what do the Legacy Focus HDs run for, street price? The originals, and the HDs look like beasts.

Even with two massive subs, my brain always tricks my ears into liking speakers with a bunch of substantial drivers like those.

Part of me would like to DIY a pair, as a bi-amped design using two 3-way cross-overs and some TC sounds 12's. (Hey, not all of our tastes are the same!)

I'd love to go demo some of those, or the HDs, in the Chicago area. Anybody know where?

...I feel the need to another 20 amp circuit already....

Legacy is in Springfield, IL, so my recommendation would be to just drive to the factory for an audition.

Used HD prices seem to be in the $5K range. The original Focus is in the $3K range, the few times you see them available. Supposedly the new SE version is simply extraordinary, but they list for just under $10K.

 

[GranteedEV]

Or this
Crown XLS2500 DriveCore Series Power Amp | GuitarCenter
The 2500 is stable into two Ohms and can be bridged for mono, and you can get $100 off with code SAVE100 hard to beat as stereo or mono amps for two at around $1100 or less.

I would not use it in bridge mode driving an ~ two ohm speaker. But that would be my recommendation in stereo mode, unless OP had the budget for the upcoming amplifier from Mola-Mola.nl

 

[KEW]

In practice, how should we view a speaker like this?
With an efficiency rating of 95dB, one would assume not that many watts are required for plenty of SPL (even in the large room), but with an impedance that dips below 2 ohms, we have got to have an amp that can put out serious current!
Would this mean that an amp like an Aragon 2004 MkII (100wpc into 8ohms, 200wpc @ 4ohms) is a good fit?
Indy Audio Labs - Aragon 2004 MKII

Unlike almost all other amplifiers, Aragon doubles its 8 ohm power when driving a 4 ohm load, and the continuous output power continues to increase into 2 and 1 ohm loads.

The above type of performance seems to be in line with TSLGuy's comments for the Quads.
I gather, since the XPA-2 is generally being discouraged, that power is not the issue (since it makes 300@8ohms and 500@4ohms), but the concern is whether or not it can comfortably sustain a 2 ohm load.
Is this a correct viewpoint?

 

[GranteedEV]

In practice, how should we view a speaker like this?
With an efficiency rating of 95dB, one would assume not that many watts are required for plenty of SPL (even in the large room), but with an impedance that dips below 2 ohms, we have got to have an amp that can put out serious current!
Would this mean that an amp like an Aragon 2004 MkII (100wpc into 8ohms, 200wpc @ 4ohms) is a good fit?
Indy Audio Labs - Aragon 2004 MKII
....
Is this a correct viewpoint?

Is this speaker actually 95db/w/m ??

What if they're rating a 91db/2.83v/m speaker, and adding 4db as an "in-room" rating.

And what if that 91db/2.83v/m is taken from a ~2db peak around 1-4khz and the speaker is 2db less efficient at 100hz. So it's actually 89db.

And if that's per 2.83v/m, and the speaker is actually 2 ohm, that means it's closer to 83db/w/m

To get a 83db speaker to 100db, you probably need ~~500 watts. Double that for 3db more.

Just a thought - I don't klnow a thing about the legacy focus. But it's entirely possible that you need more power into 2 ohms to get the desired SPL than the ~300-350 the aragon can provide.

 

[fuzz092888]

That would be fine, but the aragon MKII is a mondial design that hasn't been made in over ten years. It's still a great amp and you can find them used every now and again, but still. I wouldn't recommend the klipsch version of the aragon amps. They're good, but not as good as the mondial design.

You can still get aragon amps brand spanking new, but they're 8008 only and put 50% more power into 4 ohms. Plenty of wattage, but raises the same current concerns about whether it can sustain a 2 ohm load. Oh yea, and they're 4 grand.

When an earthquake cinenova grand 5 channel amp can be had brand new for about $2500 I'd take that over the aragon. Just my 2 cents

 

[KEW]

When you calculate the load the amp actually sees from the impedance curve and phase, it is 1.6 ohms at 20 Hz and 1.5 ohms at 70 Hz.

I doubt the EMO is robust enough for this speaker.

TLSG,
Are you referring to the XPA-1? If so, I hope you will elabrate!
My understanding of the XPA-1 is, while it may not be the most elegant or modern amp design, it is so outrageously overbuilt that it's end performance is extremely rigorous. I mean, as a monoblock:

Transformer size: 1,200VA
Broadband frequency response: (-3 dB): 5Hz to 150kHz
Power output:
1,000 watts RMS @ 4 ohm (0.1% THD)
500 watts RMS @ 8 ohm (0.1% THD)
Secondary capacitance: 120,000uF
Output devices: 24

To me the big issue with the XPA-1 is, because it is not efficient, plugging two into the same AC circuit makes household wiring into a limiting factor.

Thanks!

 

[KEW]

Is this speaker actually 95db/w/m ??

What if they're rating a 91db/2.83v/m speaker, and adding 4db as an "in-room" rating.

And what if that 91db/2.83v/m is taken from a ~2db peak around 1-4khz and the speaker is 2db less efficient at 100hz. So it's actually 89db.

And if that's per 2.83v/m, and the speaker is actually 2 ohm, that means it's closer to 83db/w/m

To get a 83db speaker to 100db, you probably need ~~500 watts. Double that for 3db more.

Just a thought - I don't klnow a thing about the legacy focus. But it's entirely possible that you need more power into 2 ohms to get the desired SPL.

Well the 95dB figure was thrown out as a guesstimate by IrvRobinson. But I am not necessarily asking in reference to this particular speaker.
My interest is developing a conceptual understanding of how this works. So let say if a speaker has 95dB efficiency.

One thing I gather from your response is that the efficiency spec is like the impedance spec in that a manufacturer may spec an optimistic nominal rating while in actually it is frequency dependent and can be all over the place. Is this right?

Fuzz,
I should have mentioned that amp was discontinued. I did not mean to be suggesting it as a solution to the OP (though a used one might be a pretty decent option). I'm just trying to get my head wrapped around the demands of efficient speakers which drop below 2ohms. And the old Aragons came to mind.
Thanks for making the clarification that I should have.

 

[GranteedEV]

One thing I gather from your response is that the efficiency spec is like the impedance spec in that a manufacturer may spec an optimistic nominal rating while in actually it is frequency dependent and can be all over the place. Is this right?

Right. In fact the "efficiency" is pretty much a function of impedance along with the sensitivity. Lower impedance generally implies lower efficiency (IE more power is required!). Higher sensitivity generally implies higher efficiency ONLY if impedance doesn't change. A 90db stated speaker may be less efficient than a 87db stated speaker.!

 

[Irvrobinson]

Is this speaker actually 95db/w/m ??

What if they're rating a 91db/2.83v/m speaker, and adding 4db as an "in-room" rating.

IMO the Focus really has a sensitivity of about 95db/2.83v. It was rated by Legacy at 96db/2.83v. For a short time I had the Focus and the Salon 2 in the room at the same time, and there was no comparison in sensitivity between the two. Over the 12 years I had it the Focus was also incompatible with certain electronics, because the volume control would need to be turned down so far that the range for low-level listening was too limited.

We must also remember that 2.83v into 2 ohms is 4 watts. In the lowest two octaves I doubt one could call the Focus efficient.

To KEW, don't confuse sensitivity with efficiency. The Focus was probably one of the least efficient speakers my friend ever measured. I'm not on the same page with TLS Guy on this speaker, but he is right that it is a torture test for an amp.

My issue with the Emotivas is only the potential noise level. Highly sensitive speakers make it more apparent. One really odd thing though, the Levinsons hissed more with the Salon 2s than with the highly sensitive Legacys. Hmmm. The Legacys are not rolled off in the upper two octaves either. Very curious behavior.

 

[Irvrobinson]

Right. In fact the "efficiency" is pretty much a function of impedance along with the sensitivity. Lower impedance generally implies lower efficiency (IE more power is required!). Higher sensitivity generally implies higher efficiency ONLY if impedance doesn't change. A 90db stated speaker may be less efficient than a 87db stated speaker.!

Ha! We posted at the same time. Obviously I think you got it right with the efficiency factor.

 

[Hocky]

That would be fine, but the aragon MKII is a mondial design that hasn't been made in over ten years. It's still a great amp and you can find them used every now and again, but still. I wouldn't recommend the klipsch version of the aragon amps. They're good, but not as good as the mondial design.

You can still get aragon amps brand spanking new, but they're 8008 only and put 50% more power into 4 ohms. Plenty of wattage, but raises the same current concerns about whether it can sustain a 2 ohm load. Oh yea, and they're 4 grand.

When an earthquake cinenova grand 5 channel amp can be had brand new for about $2500 I'd take that over the aragon. Just my 2 cents

I have an 8008 powering speakers that see .6 ohms (albeit at the other end of the frequency spectrum) in a large room and I can hit any spl I want. Pretty killer amps - I rolled a lot of very expensive amps through and nothing else intrigued me enough to keep them in place.

 

[fuzz092888]

I have an 8008 powering speakers that see .6 ohms (albeit at the other end of the frequency spectrum) in a large room and I can hit any spl I want. Pretty killer amps - I rolled a lot of very expensive amps through and nothing else intrigued me enough to keep them in place.

Don't get me wrong I think they're killer amps as well. I've been keeping an eye on a few 8008's and 4004's rolling through ebay and audiogon and seriously considered picking one up. The only reason I didn't was because I decided on a different amp that, while I'll have to save up a bit more for, I've wanted for awhile now.

But agreed, great amps. IMHO, the brand new ones aren't a great deal at $4000, but a great used one would work out pretty well.

 

[Hocky]

You can find 8008 BB for sale fairly regularly for not much more than $1k. That is a solid deal as long as you're comfortable buying older hardware. I would like to come across a couple of palladiums.

 

[fuzz092888]

The 8008's and the Palladiums are nice. There's an 8008 on ebay for $850 and two 4004 MKII's on audiogon. Both are great, especially since all of them are the Mondial designed ones and all are well under $1K. Might be crazy, but I've always thought the Mondial designed ones were superior to the Klipsch designed one, especially since the 4004's doubled down and the Klipsch did not.

I will say the Klipsch had the better aesthetics though. Very pretty and that V heat sink was always pretty cool to me.

 

[PENG]

Is this speaker actually 95db/w/m ??

What if they're rating a 91db/2.83v/m speaker, and adding 4db as an "in-room" rating.

And what if that 91db/2.83v/m is taken from a ~2db peak around 1-4khz and the speaker is 2db less efficient at 100hz. So it's actually 89db.

I agree, that is highly possible.

And if that's per 2.83v/m, and the speaker is actually 2 ohm, that means it's closer to 83db/w/m

Well, if they are even half honest, if they rate their speaker impedance 4 ohms and then say sensitivity X dB @ 2.83V, they should expect people read that as X dB @ 2.83V at 4 ohms when calculating the power required so the equiivalent sensitivity to a speaker rated 8 ohms would likely be just 3 dB less, not 6.

Still, one could consider the overall equivalent sensitivity be in the neighborhood of 86 to 88 dB/W @ 1m, or lower if Grant guessed more right than wrong. In order to cover impedance dips down to 2 ohms or less, XPA-1 should be fine but not the XPA-2. Not to say the XPA-2 can't do the job, but for peace of mind the 1 is much better because it can definitely do 500 W into 2 ohms, 250 W into 1 ohm, guaranteed..

 

[PENG]

TLSG,
Are you referring to the XPA-1? If so, I hope you will elabrate!
My understanding of the XPA-1 is, while it may not be the most elegant or modern amp design, it is so outrageously overbuilt that it's end performance is extremely rigorous. I mean, as a monoblock:


To me the big issue with the XPA-1 is, because it is not efficient, plugging two into the same AC circuit makes household wiring into a limiting factor.

Thanks!

A dedicated 20A circuit for the XPA-1 will provide 2400 VA for the 2 EMO's 1200 VA transformers, while marginal, it is not a bad match.

 

[PENG]

My issue with the Emotivas is only the potential noise level. Highly sensitive speakers make it more apparent. One really odd thing though, the Levinsons hissed more with the Salon 2s than with the highly sensitive Legacys. Hmmm. The Legacys are not rolled off in the upper two octaves either. Very curious behavior.

I never thought of that, is the EMO's noise specs that bad?

 

[Irvrobinson]

I never thought of that, is the EMO's noise specs that bad?

No, actually they look pretty good, but I remember reading that someone (ADTG?) heard hiss through his speakers on an Emotiva amp.