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Solid State amp for High-Efficiency Speakers

andrew

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I’m running 2-way active speakers comprising a Unity Horn (>350Hz) and 18” Mid-Bass Bin (80 - 350Hz) which are complemented with subwoofers (<80Hz). The set-up uses two Crown XLS 1502 amps each supporting a Unity Horn and Mid-Bass Bin. I’m now looking to get a dedicated amp for the Unity Horns that has less distortion etc. and allows me to bridge the Crown XLS amps to deliver more power to the Mid-Bass Bins as there is considerable EQ on these units.

So, basically, I’m after advice on an amp for a high-efficiency (~100dB/W/m) horn with a nominal 8 Ohm impedance. The mandatory requirements are that the amp has no noise and isn’t a heat machine. It’d be preferable to have mono-blocks so as to co-locate with the speakers (but I could take a stereo amp.). I’d assumed that the answer would be a Purifi-based amp but the emergence of the Topping LA90 Discrete has opened up another well-measured option. I'm still leaning towards the Purifi-amp option on the basis that the additional power, and ability to drive low impedance speakers, offers some flexibility down the track but am struggling with whether there are real differences between these options in my scenario. Is there any technical reason to prefer LA90 Discrete or Purifi for high-efficiency horn speakers? And what other solid-state amps are worthy of consideration?
 

GXAlan

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andrew

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Why not the Benchmark? It’s got proven reliability, customer service, etc.
Good point. It’s more expensive than the other two options (here in Australia) but might well be a good option. Your points re proven reliability and customer service are well taken.
 

Chrispy

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What do you expect to be improved upon over the XLS amps?
 
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andrew

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What do you expect to be improved upon over the XLS amps?

Good question. I’m hoping to get cleaner mid-bass as a result of being able to bridge the XLS amps into the mid-bass bins (as these have considerable EQ) AND reduced distortion on the horns (as a result of having an amp with low distortion at low power). If, of course, this is an illusion then I’ll do nothing.
 

Chrispy

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Good question. I’m hoping to get cleaner mid-bass as a result of being able to bridge the XLS amps into the mid-bass bins (as these have considerable EQ) AND reduced distortion on the horns (as a result of having an amp with low distortion at low power). If, of course, this is an illusion then I’ll do nothing.
I'd think the distortion in the speaker will outstrip any advantage in the amp.
 
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andrew

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I'd think the distortion in the speaker will outstrip any advantage in the amp.
So that just leaves having extra power on the mid-bass bins. I’ve not seen the red lights that indicate clipping but am applying a lot of EQ to get the 18” drivers down to 80Hz for x/o to the sub so thought that headroom might be a real benefit.
 

Chrispy

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What is the particular setup for eq/bass management you're using?
 
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andrew

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What is the particular setup for eq/bass management you're using?

FIR filters created in Audiolense (and, on occasion, swap to Acourate) which are processed within computer running Audiolense convolver. The current generation of filters implement steep x/o at 80Hz and 350Hz, with the 80-350Hz region having fair bit of EQ
 

Chrispy

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FIR filters created in Audiolense (and, on occasion, swap to Acourate) which are processed within computer running Audiolense convolver. The current generation of filters implement steep x/o at 80Hz and 350Hz, with the 80-350Hz region having fair bit of EQ
How is it applied to each cabinet, tho?
 

kemmler3D

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The LA90 is about as clean as you can get and at 100dB sensitivity the only thing more power from a Purifi module is going to get you is more deaf. For running horns I'd prioritize noise / distortion above all personally.
 
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andrew

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How is it applied to each cabinet, tho?

Not sure that I understand the question but here goes. Computer processes stereo into 5-channels - LHS Mid-Bass, LHS-Horn, RHS Mid-Bass, RHS-Horn, and Sub. These signals are sent via USB to a multi-channel audio interface which does D/A before passing the LHS line-level signals to one XLS1502 and RHS line-level signals to the other XLS1502. The sub line-level goes straight to an active sub.
 

Chrispy

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Not sure that I understand the question but here goes. Computer processes stereo into 5-channels - LHS Mid-Bass, LHS-Horn, RHS Mid-Bass, RHS-Horn, and Sub. These signals are sent via USB to a multi-channel audio interface which does D/A before passing the LHS line-level signals to one XLS1502 and RHS line-level signals to the other XLS1502. The sub line-level goes straight to an active sub.
That's the detail I was looking for, thanks, was just trying to picture the hardware involved. Seems it's not five channels particularly, but 2.1, tho.
 
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andrew

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That's the detail I was looking for, thanks, was just trying to picture the hardware involved. Seems it's not five channels particularly, but 2.1, tho.
Yes - 2.1 but 5 channels as the stereo speakers are active with separate power amps on the mid-bass and horn drivers. Any view as to potential benefits on extra headroom on the mid-bass?
 

Chrispy

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Yes - 2.1 but 5 channels as the stereo speakers are active with separate power amps on the mid-bass and horn drivers. Any view as to potential benefits on extra headroom on the mid-bass?
Well, still just a left/right channel with some active crossover.....not even an actual LFE channel for that matter, just a summed response for a sub I assume. I'd think your amps are sufficient already. Is this a home system? What kind of spl are we talking about?
 
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andrew

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Lower noise may also be a real benefit for the horn section (assuming you can hear some hiss with the XLS1502 currently).

I forgot to mention this topic but, yes, it's possible to hear a hiss from the horns at the listening position and getting rid of this background noise is important.
 

sarumbear

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I’m running 2-way active speakers comprising a Unity Horn (>350Hz) and 18” Mid-Bass Bin (80 - 350Hz) which are complemented with subwoofers (<80Hz). The set-up uses two Crown XLS 1502 amps each supporting a Unity Horn and Mid-Bass Bin. I’m now looking to get a dedicated amp for the Unity Horns that has less distortion etc. and allows me to bridge the Crown XLS amps to deliver more power to the Mid-Bass Bins as there is considerable EQ on these units.

So, basically, I’m after advice on an amp for a high-efficiency (~100dB/W/m) horn with a nominal 8 Ohm impedance. The mandatory requirements are that the amp has no noise and isn’t a heat machine. It’d be preferable to have mono-blocks so as to co-locate with the speakers (but I could take a stereo amp.). I’d assumed that the answer would be a Purifi-based amp but the emergence of the Topping LA90 Discrete has opened up another well-measured option. I'm still leaning towards the Purifi-amp option on the basis that the additional power, and ability to drive low impedance speakers, offers some flexibility down the track but am struggling with whether there are real differences between these options in my scenario. Is there any technical reason to prefer LA90 Discrete or Purifi for high-efficiency horn speakers? And what other solid-state amps are worthy of consideration?
One the best amplifiers on the planet is Benchmark AHB2. The support is also exemplary.
 

Chrispy

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I forgot to mention this topic but, yes, it's possible to hear a hiss from the horns at the listening position and getting rid of this background noise is important.
I've used relatively sensitive speakers as well as less so with my XLS amps and hiss hasn't entered as an issue. High efficiency bins, particularly at very high levels I don't know....
 

Musicastherapy

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I forgot to mention this topic but, yes, it's possible to hear a hiss from the horns at the listening position and getting rid of this background noise is important.
I also am using Crown XLS, via RCAs. I've heard that switching over to the balanced inputs can remedy the hiss a fair bit. Just thought I'd mention that, incase you were using yours via RCA. I'm planning to try an ART Cleanbox pro for the XLR 4v connection to see is the minor hiss is helped, also supposed to be a nice bump in headroom with the higher voltage input.
 
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