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Amplifiers known to be reliable for <4ohm speakers

ex brickie

ex brickie

pfm Member
I have an ATC all in one CD/DAC/amp (SIACD) which runs quite hot with my Boenicke speakers . Boenickes are known to be a trickier load - sometimes dipping below 4ohms.

I’ve only listened at fairly low volumes and the amp hasn’t shown signs of cutting out yet (it has a thermal switch) . But I may want to turn it up occasionally

My understanding was that ATC make amps that are very durable even under a bit of stress? The manual doesn’t specify that only 4-8 ohm speakers can be used

Just in case, what makes/models are out there that are very reliable under a difficult speaker load?

I only know of Linn Klout or LK280 used to drive very difficult Linn Saras

Has to be in a £1k to 1.5k ish second hand price range .

I might be worrying unnecessarily of course! If there are ATC amp users out there they might be able to help!
 
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ex brickie said:
I have an ATC all in one CD/DAC/amp (SIACD) which runs quite hot with my Boenicke speakers.
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Has it blown up yet?

If an amplifier is working hard it can get hot. It's not a fault, it's a characteristic. My NAP250 used to shut down regularly and get so hot you couldn't keep your hand on the top. My Meridian 105s also get very hot at high volume and shut down occasionally, they're more powerful so much less often. No damage is done, they're designed to do this.

ACT build studio gear, so it's tough. I'd be very surprised if your amp wasn't totally fine with running hot and has a thermal trip to protect it.

And 4ohms is not that bad. Old Linn speakers can drop to two.
 
Paul Hindle said:
I had the same problem during the summer months. Feeding a pair of “Old Linn speakers” :). Solution……..A pair of 135s :rolleyes:
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I used to have a pair of NAP135s, but they struggled to drive a pair of DIY loudspeakers that dipped to 3R2 around 100Hz - especially when I wanted a bit of volume. The fans came on, and you'd hear the crack of the SOA circuit kicking in on bass transients.
 
The ATC will be absolutely fine at 4ohms or below.

If you want more grunt look to Bryston, Musical Fidelity, or even a bigger ATC (SIA2-150 / P1).
 
My Marantz SR4300 and a SR7300 AV Receivers used to go into protection mode when driving 4Ω speakers. Fitting a computer fan externally on the top grille blowing air downwards into the unit instantly fixed the problem, it never happened again. Some say this was the wrong approach and the fan should have been fitted under the unit to aid convection but this was impractical as I had limited space above the amp so wouldn't have had enough ventilation if I had raised the amp up to accommodate a fan below. If you do get a computer fan get the largest diameter possible so it can be run at a lower speed (less speed = less noise) and invest in a wallwart with variable voltage so that you can find the sweet spot where the fan provides enough cooling without being audible (IIRC the wallwart I had could be set to 3V, 4.5V, 6V, 9V and 12V).
 
Parasound A21. About 400W/4ohms, and 700W/2ohms on music. And it goes into standby after 5 minutes of no music, so energy saving too! I mainly listen late at night at very low levels, but also run an 80mm computer fan at 5 volts (linear PSU), which is high enough to get it to start, but low enough to be silent. With valve amps I run multiples.
 
ToTo Man said:
Fitting a computer fan externally on the top grille blowing air downwards into the unit instantly fixed the problem, it never happened again. Some say this was the wrong approach and the fan should have been fitted under the unit to aid convection but this was impractical as I had limited space above the amp so wouldn't have had enough ventilation if I had raised the amp up to accommodate a fan below.
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Turn it round so it sucks!
 
Most of the components inside those amps can withstand temperatures of 80C and more so if the casing goes up to around 60-65C, it’s still fine.
 
ex brickie said:
I have an ATC all in one CD/DAC/amp (SIACD) which runs quite hot with my Boenicke speakers . Boenickes are known to be a trickier load - sometimes dipping below 4ohms.

I’ve only listened at fairly low volumes and the amp hasn’t shown signs of cutting out yet (it has a thermal switch) . But I may want to turn it up occasionally

My understanding was that ATC make amps that are very durable even under a bit of stress? The manual doesn’t specify that only 4-8 ohm speakers can be used

Just in case, what makes/models are out there that are very reliable under a difficult speaker load?

I only know of Linn Klout or LK280 used to drive very difficult Linn Saras

Has to be in a £1k to 1.5k ish second hand price range .

I might be worrying unnecessarily of course! If there are ATC amp users out there they might be able to help!
Click to expand...

Radford STA
 
James said:
I used to have a pair of NAP135s, but they struggled to drive a pair of DIY loudspeakers that dipped to 3R2 around 100Hz - especially when I wanted a bit of volume. The fans came on, and you'd hear the crack of the SOA circuit kicking in on bass transients.
Click to expand...
Agree, most Naim amps will struggle with high current loads.
 
Multiple pairs of output devices, plenty of heatsinking and power into 8R kept reasonably low are the things to look for in an amp to drive low impedance's safely.

Sadly many hi fi amps have completely inadequate heatsinking and rely on most people not thrashing them most of the time and a thermal cutout for if they do... Naim, older Exposure, older Meridian, some Onyx etc etc. Often penny pinching but styling even comes into it:eek: The not wanting heatsinks to "spoil the lines" of the thing...

Note that ability to drive low impedance awkward loads and ability to do so without blowing up are very different things (yes Avondale...) and many SS amps will drive without holding back until they go bang, hence protection circuitry. Valve amps OTOH will not be damaged by even the most awkward 2R load.... not that they would drive it much good either unless there was a 2R tap available.
 
Here you go:-

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Arkless Electronics said:
Multiple pairs of output devices, plenty of heatsinking and power into 8R kept reasonably low are the things to look for in an amp to drive low impedance's safely.

Sadly many hi fi amps have completely inadequate heatsinking and rely on most people not thrashing them most of the time and a thermal cutout for if they do...
Click to expand...

In use this also depends on the kind of music the user tends to play. The stats on variations in signal level and crest factor will be very different if you contrast Bach solo harpsichord with Def Lep doing an eyes-down-no-nonsense-thrash. 8-]
 
Jim Audiomisc said:
In use this also depends on the kind of music the user tends to play. The stats on variations in signal level and crest factor will be very different if you contrast Bach solo harpsichord with Def Lep doing an eyes-down-no-nonsense-thrash. 8-]
Click to expand...

Obviously:rolleyes: 5WPC would usually be more than enough to reproduce a harpsichord at realistic level whilst worst case would be heavily compressed music close to clipping.
 
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