2 ohm stable amp recomendations please

[rabbit]

Gotta be way lower than 2 ohms. Twice I've asked H/K for the test criteria used to determine the HCC number, but no reply in either case.

The only thing that makes sense is something very low, like 0.1 ohm; maybe even lower.

If we go back to the forumulas, 5,000W at 2 ohms doesn't match up with the 100A HCC spec nor the plausible output voltage for this amp.

Read the paper by Otala and Huttunen entitled Peak Current Requirements of Commercial Loudspeaker Systems JAES, June 1987 or read the section in Doulas Self's book on "Enhanced loudspeaker currents".

The amp will not deliver +/- 100 amps peak into an 8 ohm load. This is not what the HCC specs are eluding to.

You don't have to use a 0.1 ohm resistor to sink or source high currents from an amplifier. The combination of certain waveforms along with certain reactive loads along can indeed draw many times the current with respect to the nominal rated impedance of the load.

Like someone else said the H/K amps are pretty generous when it comes to the quality and the number of output devices used

 

[whoaru99]

It would just clarify things so much if we didn't need to speculate on what +/-100A HCC really meant with respect to measurement conditions. HK knows, but ain't tellin'.

And no, I'm not confusing instantaneous current with continuous current. Either way it behaves basically according to Ohm's Law.

I did read, albeit quickly, through the Stereophile link. Did you have a link for the Otala paper?

What I got out of the Stereophile article doesn't seem to contradict anything I've said, except they've gone into the compleity of impedance vs simple resistance.

However, my basic opinion is still the same. Regardless of what makes the difficult load difficult, the load/impedance numbers still have to be extremely low, likely below any real world occurence, to even get close to being able to facilitate 100A instantaneous current.

 

[automojo]

HK knows, but ain't tellin'.

Perhaps they have little time to do your home work for you?. The info is out there in the above mentioned papers, I will try to find the links.
Again this is all interesting, but it doesn't replace real world testing ,listening and observation of the amp/ speaker relationship-Julian Hirsch rarely met a amp he didn't like-he was more concerned with measurments than a actual listening test, interesting read for sure, but I found over those years not to really trust his "sound" judgement.

 

[whoaru99]

HCC is HK's spec, not mine. HK is making the 100A HCC claim, not me. Why should I have to do any homework to find out what it really means besides asking them? Which, again, I have done twice... with no reply.

I'm merely asking, albeit in a roundabout way, the specifics of how this number came to be. A question nobody has yet answered, nor likely ever will, with cold, hard facts.

This is not about sound, this is not about whether HK amps are good or bad. It's about a published number/spec and understanding what it really means.

The basis of HK's 100A HCC claim/spec is not contained in those papers.

Those papers, at least the article linked to Stereophile, merely describe ways in which speakers can be more demanding than their nominal impedance indicates. That has nothing to do with how much peak power any given amp can produce.

 

[rabbit]

It would just clarify things so much if we didn't need to speculate on what +/-100A HCC really meant with respect to measurement conditions. HK knows, but ain't tellin'.

And no, I'm not confusing instantaneous current with continuous current. Either way it behaves basically according to Ohm's Law.

I did read, albeit quickly, through the Stereophile link. Did you have a link for the Otala paper?

What I got out of the Stereophile article doesn't seem to contradict anything I've said, except they've gone into the compleity of impedance vs simple resistance.

However, my basic opinion is still the same. Regardless of what makes the difficult load difficult, the load/impedance numbers still have to be extremely low, likely below any real world occurence, to even get close to being able to facilitate 100A instantaneous current.

Your assumption is for a sine wave signal only. For non-sinusoidal and asymmetrical waveforms used by Otala the story is completely different for a reactive load.

I don't have the paper by Otala but this issue is discussed a bit in Self's book.

The real issue is whether this type of waveform actually occurs in program material.

 

[automojo]

HCC is HK's spec, not mine. HK is making the 100A HCC claim, not me. Why should I have to do any homework to find out what it really means besides asking them? Which, again, I have done twice... with no reply.

I never mentioned it was your claim. Asking one source (H/K)is hardly a thorough investigation.

And H/K isn't the only one mention high current amps, take a look at the latest Audio Advisor catalog. perhapss you should look into those manufactors claims as well, to have a fair and unbiased look at amplifier current ratings. Maybe those manufactors might help shed some light on their ratings.

When you look at, for example a Citation 12, 16, 21, PA2400, at take a look at their reviews- many people find they are excellent amps for driving low amp, or complex speaker load with no distress. This, regardless of paper specs tells me something. Real world testing.

 

[whoaru99]

[... Asking one source (H/K)is hardly a thorough investigation.

And H/K isn't the only one mention high current amps, take a look at the latest Audio Advisor catalog. perhapss you should look into those manufactors claims as well, to have a fair and unbiased look at amplifier current ratings. Maybe those manufactors might help shed some light on their ratings.
Regardless, looking at paper ratings without real world testing, is agian interesting at best, but not really informative.

Seriously...who would you suggest I ask about HK's HCC spec if not HK? Do you honestly think some other mfg is privy to their testing parameters?

Comparing specs other amps? That means nothing unless you know the test conditions/basis.

That's paramount to two people saying their car goes 100mph, but one means in the 1/4 mile and one means top speed. Unless you know the basis, one cannot assume the raw numbers are comparable.

I am in no way challenging the overall performance of this amp. I acknowledged early on that I'm sure it's a fine sounding and fine performing amp. However, a vague spec has been published and it's often cited in discussion where HK comes up. I want to know what it means, exactly, not speculatively.

 

[automojo]

Seriously...who would you suggest I ask about HK's HCC spec if not HK? Do you honestly think some other mfg is privy to their testing parameters?

Comparing other amps? That means nothing unless you know the test conditions/basis.

That's paramount to two people saying their car goes 100mph, but one means in the 1/4 mile and one means top speed. Unless you know the basis, one cannot assume the raw numbers are comparable.

Find the papers on the people who designed the amps and their theory. You act like H/K is trying to hide something- I really doubt that. My thought would be, with the world wide web and your finger tips -DIY my friend, instead of complaning about H/K dissing you.
I agree about raw numbers, they are just that, and in the end probably have less impact than one might think, on how these amps perform in real world conditions under real world and/or complex loads. Getting some of these amps together with a few low ohm, difficult to drive speakers may be more enlightening than a number/theory search IHMO.

 

[whoaru99]

Believe me, I have searched high and low for solid information on this HCC spec, and there is nothing that I have found so far. My questions span multiple audio forums.

As best I can recall, I have never said I doubted the 100A number. What I do doubt is 100A into any typical, or even demanding, speaker load.

If HK says it produces 100A instantaneous high current it probably does. But, under what parameters? Something that reflects real world usefulness, or under condtions that merely look good on paper?

Again, this "quest" is not about anything except the spec. Clearly HK wants people to think it means something otherwise they wouldn't continue to put the spec in their product literature.

What does it really mean?

 

[automojo]

As soon as I run across those papers I will foward them- I know I have several hard copies somewhere I printed.
Not a very good, or techinal explination- but looking at past H/K literature- they do seem to imply this does mean the ability to drive complex loads, and most of their amps, particuliary the Citation and larger models do this very well with no distress- and I know their idea was to have full power available at the full frequency range without any dips, etc. And this without any current limiting devices which H/K usually stays away from as they think it hinders the sound (similiar to their direct coupled desings-they assume some risk in speaker health with the direct coupled design if you have a transistor failure- your speakers will more than likely be damaged as well. These amps (PA2400-Citation 22) also have to be adjusted periodically, or they may drift. But they feel the lack of extra componets in the sound path is worth the risk.
When the desinger of the H/K Signature 1.5 (built by Levinson)was given what H/K wanted-they wanted this full rated power to extend well beyond this range, for example 5-45 if I recall, but they found the H/K 1.5, and they other amps he was desinging weren't really happy at such a wide frequency range, and had to tone them down on top to 35 or so.
The definitley have taken a different route than for example McIntosh-whose Autofomer seems little different than a 70volt matching transformer on a PA system. Those Autoformer amps always blew my mind, a huge heavy amp with a massive power supply- what are they afraid of?? As I recall over the years, there low ohm perfermance testing was average, if not below at best-but alot of people really like their sound-to me that says something as well. Before you begin, I am well aware of their Autoformer, and tight power supply regulation theories-I don't agree with it, but appreciate their thoughful design.
I wish I could recall the specifics of those papers, but I can't. If there is chance I can't eventually find those copies, I have a pretty good idea on how to find them- I have a due favor from a friend I'm have little doubt can get these in my hands.

 

[rabbit]

Believe me, I have searched high and low for solid information on this HCC spec, and there is nothing that I have found so far. My questions span multiple audio forums.

Like I said the most obvious source is the article published in the Audio Engineering Society.

http://www.aes.org/e-lib/browse.cfm?elib=5198

AES E-Library: Peak Current Requirement of Commercial Loudspeaker Systems by Otala, Matti; Huttunen, Pertti
Peak Current Requirement of Commercial Loudspeaker Systems
Measured terminal impedances of several commercial loudspeaker systems are developed into their equivalent electrical circuits by using the Brune network synthesis method. The synthesized circuits accurately describe the properties of the load as seen by the amplifier feeding the loudspeaker system. A group of non-sinusoidal audio signal sequences, which cause the loudspeaker system to draw momentary currents considerably in excess of what could be expected from the rated terminal impedance is identified using computerized network analysis methods. The maximum value of peak current of peak current reported for a commercial loudspeaker system is 6.6 times larger than that of an eight ohm resistor. The current peaks typically last a few hundred microseconds. The current peaks are caused by simultaneous parallel excitation of several of the drivers of a multiway system, by summation of cancellation currents originating from the energy stored in the mechanical and electrical reactances of the circuit, and by impedance transformation effects in the crossover network. The results imply that for short periods of time, an amplifier should be able to drive, with full output voltage swing and without appreciable distortion, loads equal to a resistor of one ohm.
Paper Number: 2293 AES Convention: 79 (October 1985)
Authors: Otala, Matti; Huttunen, Pertti
Affiliations: Otamation Inc., Helsinki, Finland ; Polarpro Inc., Kuusamo, Finland (See document for exact affiliation information.)

 

[whoaru99]

Again, I see no relationship between these articles and the HK HCC spec.

OK...speakers can draw several times more current than their nominal impedance might suggest. I know that, I have known that, that's never been the point.

The point is HK says the amp can deliver 100A peak current OK, fine, I believe it. What I want to see are the test parameters they used to get the HCC spec. That's all I've ever been after....and still don't have it.

 

[rabbit]

Again, I see no relationship between these articles and the HK HCC spec.

OK...speakers can draw several times more current than their nominal impedance might suggest. I know that, I have known that, that's never been the point.

The point is HK says the amp can deliver 100A peak current OK, fine, I believe it. What I want to see are the test parameters they used to get the HCC spec. That's all I've ever been after....and still don't have it.

How can you say this if you haven't read the AES article ??

 

[SoCal Sam]

"The current peaks typically last a few hundred microseconds."

100A of dynamic headroom isn't out of the question. However, the key spec is what can the HK deliver continuously with a 2 ohm load?

 

[whoaru99]

How can you say this if you haven't read the AES article ??

Spare me the agony. Does the AES article talk specifically about the HK HCC spec?

 

[whoaru99]

"The current peaks typically last a few hundred microseconds."

That reference to peak current demand has no specific relevance to what the HK amp can deliver.

All it means is that's the typical duration of peak demands they observed during the research. What a load demands and what a source can deliver are two completely different things.

 

[rabbit]

That reference to peak current demand has no specific relevance to what the HK amp can deliver.

All it means is that's the typical duration of peak demands they observed during the research. What a load demands and what a source can deliver are two completely different things.

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.

 

[SoCal Sam]

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?

 

[rabbit]

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?

100A momentary.
Impedance = Complex speaker load impedance.
Signal = Non sinusoidal and asymetrical.

 

[Jon_Logan]

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.