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So I have a pair of heresies and a pair of la scalas. Both of which are rated at 100 watts rms. I currently have a power amp rated at 100 watts rms per channel, with a channel A and channel B speaker switches. My system gets to go outside on occasion. to play so I want a full 100 watt power to both pairs. Do I need a second amp, one for each pair, I'm thinking maybe when I use both the A and B switches only half the power goes out to each pair. I'm using a SAE rack with the A202 amp; would I get more volume using separate amps for each pair

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First thing is if you were going to play them both at the same time very loudly (which I assume from the statement that you want 100 watts to each), you should use two amps.

 

The impedance is dynamic (not just 8 or 4 ohms) and the music is dynamic so there really isn't a "100 watts to each".

 

Now that said, most of the time your speakers will be running under 10watts or so when playing quite loudly so you should be able to hook them up together and not blow anything up.  If you demand ridiculous volumes then all bets are off.  This is all provided the amp has been serviced and is in new shape.  Considering the possible age of the amp, you could blow up one or all of your equipment.

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Those speakers are so efficient I couldn't imagine any amp being driven to clipping, even if both pairs were on the same amp.

 

I'd run both on the same amp and as long as the output isn't distorted, you're not dangerously overdriving your amp.

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Hi Paul, If you haven't tried using both A and B speakers outputs at the same time with your two sets of speakers, what's the hold up :-) From my experience, you will find the La Scalas outshine the Heresys, but still sound good. If you can run a long test of loud volume and monitor your amp and all is good, you are set. If you still want more volume, then yes, separate amps would be necessary. You may also want to consider a subwoofer or two.

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14 hours ago, paul of hot springs said:

I want a full 100 watt power to both pairs. Do I need a second amp, one for each pair, I'm thinking maybe when I use both the A and B switches only half the power goes out to each pair. I'm using a SAE rack with the A202 amp; would I get more volume using separate amps for each pair

 

Use a separate power amp.  Get one with an input level pot.

 

If your amp has the A and B channels wired in parallel, the impedance will be cut in half, making the speakers harder to drive. 

 

Do you have the original Heresy models ("Heresy I")? 

 

The Heresy and the La Scala are very different in sensitivity.  To achieve a volume level requiring 6.3 watts into a La Scala, it takes 45 watts into a Heresy.  The resulting SPL from either (6.3 watts into a La Scala or 45 watts into a Heresy) would be about 105 dB max in a 3,000 cu.ft. room.  With a full 100 watts (each speaker pair with its own 100 watt amp), you would get a little more than 108 dB (each doubling of power in watts provides 3 dB of increased sound pressure level).   Outside, who knows.  Without room gain, you would loose at least 6 dB, I think.  It's conceivable that backing up the speakers against an outside wall of the house might help, providing the wall is near where your guests, and the police, will gather.

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How much power? Bwhahaha... :lol: Good one.

Seriously though I have 250 Watts on each Bell's and they seem to handle them without issue. However,  I'm barely using the fraction of that power even at unhealthy listening levels. As a test I turn up the volume closed my front door walked out to the street in front of my house and I could clearly hear the music playing. It was insane.  You'll never be in the same room at that music volume. I bet you I was barely hitting 50 Watts if that.

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6 hours ago, Rxonmymind said:

How much power? Bwhahaha... :lol: Good one.

Seriously though I have 250 Watts on each Bell's and they seem to handle them without issue. However,  I'm barely using the fraction of that power even at unhealthy listening levels. As a test I turn up the volume closed my front door walked out to the street in front of my house and I could clearly hear the music playing. It was insane.  You'll never be in the same room at that music volume. I bet you I was barely hitting 50 Watts if that.

 

I had an amp with a power meter on it.  I once fed the Klipschorns 25 watts, at the end of a Mahler symphony.  It was ultra loud in my room, with a Rat Shack SPL meter, "C" weight, "Fast" hitting 110 dB, and a bit more.   The Belle and the La Scala have the same efficiency as each other, and about 2 dB less than the Khorn (only when measured with full range pink noise, rather than the typical 500 to 2kHz; the efficiency difference is caused by a deeper bass reach of the Khorns).  As I said, the La Scala would need only 6.3 watts to produce 105 dB in a average room.   That is THX/Dolby/Audyssey Reference level for Full Scale (fs; peaks, above 80 Hz ... actually, THX's original specs were "108 dB for "infrequent but recurrent peaks" above 80 Hz ... perhaps they've lightened up a bit.).  Below 80 Hz, subwoofer level, fs 115 dB.   Outside, any speaker might need many more watts, if you consider bass frequencies.  Both the Belle and the La Scala are a bit light on the bass (below, maybe, 60 Hz) anyway.  The temptation to turn up the bass at an outside event is considerable.  The Heresy needs 7 times the power in watts as either the Belle or the La Scala.

 

As others have said, the OP might consider a powered subwoofer (a powerful one!).

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Just don't mistake any of these post to mean you can turn up your 100 wpc stereo full blast, if you do you will be posting looking for replacement parts you toasted.  

Also if it were me, I would leave the Heresy's inside and build yourself a horn sub to go with the LaScala's outside, or inside.

 

And Welcome................................LaScalas sound great outside

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NORMALLY, when  you have speakers "A" and speakers "B" running at the same time, from the same STEREO amp which uses one power supply, OR one power supply PER CHANNEL, and you run pairs oif speakers on both "A" and "B" at the same time, what you are "in effect" doing is reducing the ohms going to each pair of speakers...for example, if the output for one pair of speakers on (for instance) speaker "A" is nominally 8 Ohms, then with speakers running on Speaker "A' and another set running on speaker "B" cuts that nominal ohm rating down to all the speakers being driven.

 

SOME amps (not many but SOME!!) do NOT have that issue, though,  because they incorporate totally separate amplifier sections within them...one section for Speaker "A" and one for speaker "B".

 

Because the LaScala is way more efficient than the Heresy, the LaScalas will be much louder than the Heresys because all four speakers will be getting the same input power.

 

There is a way around this, though, using One amp and one preamp....but the preamp will be the key to this puzzle, and the amp needs to have two sets of "pre-amp IN" connections.  If the power amp has that, then you can use a FOUR CHANNEL preamp, with a "joystick" balance control...OR separate front/rear balance controls...and have all four speakers running at the some listening level so that the LaScalas do not "drown out" what the Heresys are producing.

 

Make sense?

 

You accomplish the same thing using a quad preamp section with a PAIR of stereo amps.

 

ADDITIONALLY, you can use a quad pre-amp and two stereo amps...to run one stereo source to one set of speakers while using another source to play the second set of speakers....by using the quad source inputs on the preamp...front left and right for one source, and rear left and right for the other source...and connect the outputs for the front to one stereo amp preamp inputs, and rear to the other stereo amp preamp inputs...which is nice for having the Lascalas play something in one room (or outside), while the Heresys are playing something else in another room (inside).

 

Make sense?

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I cringe thinking about taking my meager-but-cherished  Heresys 'outside' - especially with the rapid onset of summer rains. Have you considered buying a pair of dedicated molded enclosure passive PA speakers, like Behringer B212XL/B215XL with their 12"/15" LF driver and Ti 1.75" horn-loaded driver? They reportedly sound pretty decent, the 15" version has an SPL of 96 dB, weigh less than 40lb, and are reasonable cost - $160/$220 shipped/ea (Amazon). I still wouldn't get them wet - the molded handles make them easier to move - quickly. There is a 135 pg thread on AVSforum on their HT use. They look like they'd almost enjoy being scuffed up a bit.

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