Power amplifiers that excel with very low impedance - and low efficiency loads
- Thread starter Jim Smith
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Re: Power amplifiers that excel with VERY low impedance - and low efficiency - loads
Luxman M900u. Stable to 1ohm.
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Luxman M900u. Stable to 1ohm.
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Feanor
Member
Re: Power amplifiers that excel with VERY low impedance - and low efficiency - loads
Well my Purifi amp has an output impedance of 67 microOhms and, per specs, is fine with 2 Ohm loads, delivering 450 watts
Accordingly Damping factor at 2 Ohms = 29,851, which poor if you like flabby bass :cryforjoy:
Well my Purifi amp has an output impedance of 67 microOhms and, per specs, is fine with 2 Ohm loads, delivering 450 watts
Accordingly Damping factor at 2 Ohms = 29,851, which poor if you like flabby bass :cryforjoy:
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a.wayne
Well-known member
Re: Power amplifiers that excel with VERY low impedance - and low efficiency - loads
Whats the load Jim and desired listening levels ...?
Whats the load Jim and desired listening levels ...?
Feanor
Member
Re: Power amplifiers that excel with VERY low impedance - and low efficiency - loads
Ah ... so client endorsements are not hearsay: I'm informed.
Ah ... so client endorsements are not hearsay: I'm informed.
a.wayne
Well-known member
Re: Power amplifiers that excel with VERY low impedance - and low efficiency - loads
Doesn't have enuff heatsinks , outputs or PSU to sink current into a 2 ohm or lower loads , most Class D are really designed for 8 ohm loads with a low z of 4 ohm being optimum.
Regards
Doesn't have enuff heatsinks , outputs or PSU to sink current into a 2 ohm or lower loads , most Class D are really designed for 8 ohm loads with a low z of 4 ohm being optimum.
Regards
Feanor
Member
Re: Power amplifiers that excel with VERY low impedance - and low efficiency - loads
In your OP you didn't give examples of speakers with "very" low impedance combined with very low efficiency (sensitivity). In practical terms, what portion of widely available consumer speakers meet these criteria?
I'd say there aren't very many. Meanwhile class D amps like Purifi, Hypex, and ICEpower typically lead with their 4 Ohm rates and are quite capable of driving such loads in normal consumer practice. Some unusual situation might justify fans for better ventilation but such a resort is not emphasized by the makers.
If you really want to drive very low impedance to high levels and/or with very insensitivity speaker, you ought to look at professional amps by Crown, QSC, et al.; most of these are designed for these circumstances. E.g. the QSC RMX5050A will deliver 2500 wpc into 2 Ohms and will do so all day.
Of course, these amps don't have much audiophile cachet, but they do the job. (If you want euphonic distortion, you can can put a tube preamp upstream.)
In your OP you didn't give examples of speakers with "very" low impedance combined with very low efficiency (sensitivity). In practical terms, what portion of widely available consumer speakers meet these criteria?
I'd say there aren't very many. Meanwhile class D amps like Purifi, Hypex, and ICEpower typically lead with their 4 Ohm rates and are quite capable of driving such loads in normal consumer practice. Some unusual situation might justify fans for better ventilation but such a resort is not emphasized by the makers.
If you really want to drive very low impedance to high levels and/or with very insensitivity speaker, you ought to look at professional amps by Crown, QSC, et al.; most of these are designed for these circumstances. E.g. the QSC RMX5050A will deliver 2500 wpc into 2 Ohms and will do so all day.
Of course, these amps don't have much audiophile cachet, but they do the job. (If you want euphonic distortion, you can can put a tube preamp upstream.)
a.wayne
Well-known member
Speakers which meet such a low efficiency criteria is for a different debate , the focus right now is on amps which do meet the criteria necessary to drive such transducers..!
BTW i have tried most of those class D amps you listed at low Z they do not meet ( not speculating as you are ) the criteria , well not if Proper Timbre and natural sound is important they will work but mostly thinking where the Bel canto Black or Merrill’s element Class D approach may do the trick , Pricey and may not handle the thermal load , which is pretty much.
Regards
PS: Tried both the high powered QSC and Crown, their fans run on High constantly to handle the thermal load and not high fidelity sounding at all ..!
BTW i have tried most of those class D amps you listed at low Z they do not meet ( not speculating as you are ) the criteria , well not if Proper Timbre and natural sound is important they will work but mostly thinking where the Bel canto Black or Merrill’s element Class D approach may do the trick , Pricey and may not handle the thermal load , which is pretty much.
Regards
PS: Tried both the high powered QSC and Crown, their fans run on High constantly to handle the thermal load and not high fidelity sounding at all ..!
Feanor
Member
l
So fair enough. Without specifying speakers that meet the criteria the question is ... uhmm ... academic.
Then too what's "proper timbre and natural sound" is, in my 50 years of hi-fi listening, highly subjective. A majority of audiophiles prefer euphonic to accurate, but not all.
So fair enough. Without specifying speakers that meet the criteria the question is ... uhmm ... academic.
Then too what's "proper timbre and natural sound" is, in my 50 years of hi-fi listening, highly subjective. A majority of audiophiles prefer euphonic to accurate, but not all.
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a.wayne
Well-known member
Everything in audio is euphonic and to preference, it’s why so many colorful choices ..
Regards
Regards
TheOctopus
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McIntosh amps with autoformers. 8,4,2 ohms, same full power rating.
Bench testing reveals obvious, superb performance. McIntosh MC501 monoblock power amplifier Measurements | Stereophile.com
Bench testing reveals obvious, superb performance. McIntosh MC501 monoblock power amplifier Measurements | Stereophile.com
a.wayne
Well-known member
You should read that report carefully ..
TheOctopus
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You should read that report carefully ..
I did and I owned a pair of MC501’s for years. Thermal stability was never an issue. Bench testing at 1/3 rated power continuous makes many amplifiers heat up. McIntosh shuts down to prevent failure of components under thermal stress which is smart.
TheOctopus
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Re: Power amplifiers that excel with VERY low impedance - and low efficiency - loads
I don’t know, do you have something to complain about to Mike?
I don’t know, do you have something to complain about to Mike?
kzhtoo
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Re: Power amplifiers that excel with VERY low impedance - and low efficiency - loads
Do I have to?
Do I have to?
TheOctopus
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Re: Power amplifiers that excel with VERY low impedance - and low efficiency - loads
What is the point of your comments on this thread?
What is the point of your comments on this thread?
a.wayne
Well-known member
W
No they dont , you should stop winging it like this Serge, the 501 heatsinks are woefully inadequate and will have thermal issues on low Sensitivity loudspeakers (can use up to 8 times the avg watts for normal listening) and no the 1/3 power level pre conditioning is very rarely ever failed by competently designed amps with proper SOA parameters ..!
Yes very rare to see a thermal failure like that and worse in such a short order ..
Regards
PS: The 1/3 power preconditioning test became order due to the woefully designed High output SS amps of the time , specifically Phase Linear. The very popular power unit by Bob Carver had a pension for failing into a fireball and was woefully heat sinked and no SOA to talk of..
No they dont , you should stop winging it like this Serge, the 501 heatsinks are woefully inadequate and will have thermal issues on low Sensitivity loudspeakers (can use up to 8 times the avg watts for normal listening) and no the 1/3 power level pre conditioning is very rarely ever failed by competently designed amps with proper SOA parameters ..!
Yes very rare to see a thermal failure like that and worse in such a short order ..
Regards
PS: The 1/3 power preconditioning test became order due to the woefully designed High output SS amps of the time , specifically Phase Linear. The very popular power unit by Bob Carver had a pension for failing into a fireball and was woefully heat sinked and no SOA to talk of..