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2 ohm stable amp recomendations please

Jon_Logan said:
It would be nice to have the test method, so apples could be compared with apples. How unusal is the HK really?

I have an arbitrary waveform/burst capability. I can shoot whatever uglieness the test requires, into the amp. I don't know how much detail Matti gave on the AES paper, and my AES subscription has been fallow a couple years. I'm not paying for the download.
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There is a brief description of it in Douglas Self's Handbook on Audio Power Amplifier Design.
 
rabbit said:
Sorry what do you mean ??

If the instantaneous current drawn by the load is 100 Amps then this is what the amplifier is supplying to it in accordance with Kirchoff's current law and the conservation of charge.
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What you say is correct, but it assumes the source can supply that much current.

When I start my car, the peak current draw is hundreds of amps. The car starts because the large 12V battery can supply it.

Now, replace that large 12V battery with eight AA batteries in series to get the same 12V.

Does the car start? No, it does not. Why not? Because the starter demands hundreds of amps but the small AA batteries cannot supply it.
 
SoCal Sam said:
OK, let's get to the bottom of this. Who is claiming the HK can deliver 100A at what impendance and is this figure continuous or momentary?
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HK claims this in their product literature. 100A instantaneous high current capability.

The bold text has been my point all along. Those quantities are undefined so there is no way to know whether this "100A HCC" has any real teeth, or is merely paper tiger.

What is the defined load for the test?

Instantaneous/momentay is too vague. Does that mean 1 microsecond, 1 millisecond, or what?
 
rabbit said:
100A momentary.
Impedance = Complex speaker load impedance.
Signal = Non sinusoidal and asymetrical.
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Those are assumptions on your part for the HCC spec (except the 100A figure given by HK).

The whole point is that we do not know what methodology HK used to determine the 100A HCC rating.

Virtually all amps are rated by the mfg using only simple resistance. I suspect, no I'd wager, the same for HK's HCC rating.
 
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whoaru99 said:
HK claims this in their product literature. 100A instantaneous high current capability.

The bold text has been my point all along. Those quantities are undefined so there is no way to know whether this "100A HCC" has any real teeth, or is merely paper tiger.

What is the defined load for the test?

Instantaneous/momentay is too vague. Does that mean 1 microsecond, 1 millisecond, or what?
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It means they have a great marketing department... :thmbsp:
 
Jon_Logan said:
Maybe they were calculating the short duration current that could be delivered by their caps into a screwdriver?
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This is basically what I'm trying to ascertain, and it is my feeling that is essentially what the answer really is. Something on the order of a 1-cycle tone burst into a dead short.
 
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I am late to this thread but I just got this amp from ebay after some reviews on other sites. this is a so called pa amp but it is very musical and capable of driving almost any load. Here are some top off pictures of this sweet 750 wrms per channel @ 8ohm amp.
Full specs and where to buy here...
Specs
◆ 1500 Watts RMS @ 8 Ohm Bridged Mono
◆ 2 X 2250 Watts RMS @ 2 Ohms
◆ 2 X 1250 Watts RMS @ 4 Ohms
◆ 2 X 750 Watts RMS @ 8 Ohms
◆ Inputs: 1/4", XLR ,
◆ Outputs: Banana Binding Post, Speakons
◆ Left / Right Level Controls
◆ Dual Fan cooling System
◆ Ground Lift
◆ Protect LED
◆ Peak LED
◆ Rack Mountable
◆ Power Supply: 110 Volt
◆ Dimensions ( W x H x D ) 19" x 4" x 17"
◆ Weight: 48 lbs






http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=190284060887&ssPageName=ADME:X:AAQ:US:1123
 
For the instantaneous current that HK is bragging about: if their rail voltage is 70volts, and the Vsat of their output transistors was 0 ohms, the load would have to be 0.7 ohms for 100 Amps.

R=E/I I= the 100A, E would be the rail voltage. I know that the capacitance in the HK's are "okay".... pretty normal. I know the number of output transistors and the Vsat is "okay" ....pretty normal

It would seem to me, they found an Esoteric way to measure, beating other manufacturers to the marketing punch. Emperors new clothes. I've seen HK's blow up in the normal fashion. ...sometimes worse. I really don't think they've got any edge on anybody else.
 
drz01 said:
I am late to this thread but I just got this amp from ebay after some reviews on other sites. this is a so called pa amp but it is very musical and capable of driving almost any load. Here are some top off pictures of this sweet 750 wrms per channel @ 8ohm amp.
Full specs and where to buy here...
Specs
◆ 1500 Watts RMS @ 8 Ohm Bridged Mono
◆ 2 X 2250 Watts RMS @ 2 Ohms
◆ 2 X 1250 Watts RMS @ 4 Ohms
◆ 2 X 750 Watts RMS @ 8 Ohms
◆ Inputs: 1/4", XLR ,
◆ Outputs: Banana Binding Post, Speakons
◆ Left / Right Level Controls
◆ Dual Fan cooling System
◆ Ground Lift
◆ Protect LED
◆ Peak LED
◆ Rack Mountable
◆ Power Supply: 110 Volt
◆ Dimensions ( W x H x D ) 19" x 4" x 17"
◆ Weight: 48 lbs






http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=190284060887&ssPageName=ADME:X:AAQ:US:1123
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RMS! Now that is what I look for. I wonder at what THD?
 
Unfortunatly this thread ended up being more of a H/K bashing than sound amp recommendations.
Regardless of one memeber not getting his H/K HCC answers, (what this has to do with the OP is beyond mebest suited for it's own thread) the point of the thread was amps they can drive stable 2 ohm loads. Very few are out there, and perhaps a pa style amp is the answer. There seem to be a number of units, such as in the PE catalog that will fit that bill, and more likely your budget.
You will have to deal with posible fan noise- hopefully they sound decent, but it probaly your best choice, to avoid melting down a traditional audio amp.
Regardless of all the mathmatical stuff, is really how the amps sounds, and how well it drive the speakers that is important-I agree the rest is marketing stuff that the unwary get caught up, and feel a need to prove or justify.
Personally, I could care less about the numbers, I'm not a engineer, but a music lover, and it's the sound that matters.
 
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While it's true that questions were raised about HK's Current spec, published specs for an amps performance at 2 ohms don't hold much water for me. The manufacturer's reputation adds a lot along with their published specs. 2 ohms is one thing on a resistive (only) load. While I believe Crown is one of the more conservatively rated amp companies out there, I've repaired plenty of their amps that drive shaker tables ...Techron 7650. 2 ohms is difficult, no matter how you slice it. It's impossible to say that an amp is stable, or reliable into a mostly 2 ohm complex load. The greater the distance from a 2 ohm load you can stay, the more reliable the amp.
 
Jon_Logan said:
, published specs for an amps performance at 2 ohms don't hold much water for me. .
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I agree. The reputation of the manufactor, and a quick physical look at the power supply are probably your only clues as to it's potential.
That was my main agrument, going along with the OP. You can get all worried about how a manufactor rates this or that amp, (HCC, contstant, momentray amps etc) or be ticked off you don't get a response (they ain't telling-etc) but all of this has little or nothing to do how said amplifier will perform under real world listening conditions, with a complex or low ohm speaker load.
You can't examine a amplifiers published specs, and then say, with out a doubt, how exactly that amplfier will perform.
Get a model of the amp, and give it a try under varing conditons you expect, and then report your findings.
In my experience, many H/K amps do a wonderful job with Infinitys (many are hard to drive) along with a number of the Yamaha M series amps, and Kenwoods Basic M2, and that was the question of the OP-not the validity of HCC, or other manufactor current specs for their amps.
Those amps would be my recommendation, the Kenwoods and H/K can usually be had a realitively bargin prices too boot. The rest is best started in another thread IMHO, beciase it has little real world realivency to the subject at hand.
 
whoaru99 said:
Those are assumptions on your part for the HCC spec (except the 100A figure given by HK).

The whole point is that we do not know what methodology HK used to determine the 100A HCC rating.

Virtually all amps are rated by the mfg using only simple resistance. I suspect, no I'd wager, the same for HK's HCC rating.
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If you are that interested in it why don't you get the Otala paper and read it instead of speculating about it because you are just going around in circles. The paper will most likely discuss the conditions of which the tests are made including the simulated loudspeaker load.

I don't have any problems about the H/K claims whether they are real or imaginary. The simple fact of the matter is that I have used the HK PA2400 with my RS4.5's since I got them and I have had no problems with premature clipping or over current protection muting or any other intrusive limiting. You can tell by their circuit topology that they are no lightweight contender.

These amps can be picked up for a bargain price because people don't know about their capabilities of driving difficult to drive loads. They are a much better proposition than many larger and much more expensive amps and receivers designed to deliver lots of power into 8 ohm loads only and which can literally destroy expensive emit tweeters even at low volumes ;)
 
rabbit said:
If you are that interested in it why don't you get the Otala paper and read it instead of speculating about it because you are just going around in circles. The paper will most likely discuss the conditions of which the tests are made including the simulated loudspeaker load.

I don't have any problems about the H/K claims whether they are real or imaginary. The simple fact of the matter is that I have used the HK PA2400 with my RS4.5's since I got them and I have had no problems with premature clipping or over current protection muting or any other intrusive limiting. You can tell by their circuit topology that they are no lightweight contender.

These amps can be picked up for a bargain price because people don't know about their capabilities of driving difficult to drive loads. They are a much better proposition than many larger and much more expensive amps and receivers designed to deliver lots of power into 8 ohm loads only and which can literally destroy expensive emit tweeters even at low volumes ;)
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I agree Rabbit-your experience with the PA2400 driving Infinities tells way more than speculation or a need to find out H/K "ain't tellin" specs-in reality they are irrealivant-the proof is, as they say in the pudding, and your experience speaks volumes.
I agree the PA2400 is a wonderful amp, one of the top five amps I have heard, period. And I have had it driving several models of Magnapans, Klipsch, DLK, B&W and Canton, and have come to the same conclusion.
The H/K Signature 1.5 (built by Levinson) improves on it, very slightly though.
A improvement in clarity, slightly more transparent, but otherwise the two amps are very similiar. The 1.5 is better spec wise on paper, particuliarly it's rating into 4 ohms, as it doubles it's rated 8 ohm power. into 4 ohm loads.
And I have yet to compare it driving 1.6 maggies, but I imagine the difference to be slight. To me this clealry validifies the specs have little to do with the actual listening experience-and are some what meaningless without having the equipment in front of you.
Unless you have actual experience with these amps driving similair low ohm, or complex loads, speculating on how H/K, or any other manufactor rates their amps isn't particuliarly useful to the original thread- *amps capable of driving Infinites* (which aren't 2 ohm, if at all at any frequency, but are probably in the 3 ohm range, as well as inefficient-a double whammy), and comes off kind like bashing for no useful reason.
Perhaps interest in H/K's rating practices is better suited to a original thread.
 
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