How to fix my detailed, accurate but BRIGHT system

Another thing to remember about the so-called doubling down amps. Some of the manufacturers' amps don't exactly double down. The simply make the 8 ohm output higher than the advertised power. For example a 200/400 watt amp can have 300 watts at 8 ohms instead of 200 and the 4 ohm output is 400 wpc. In this way they get to claim it doubles down (all amps that double down must be better!) when in fact it doesn't. Nobody complains because the 8 ohm power is higher than rated but in this case it's a marketing choice - double down is better than the value of 8 ohm power. In the audiophile market this marketing technique is likely to hold more weight with buyers.

The Krell 400xi is a great example of this although they seem to take both marketing routes - advertising doubling down of power and not quite truthful specifications. Adverstised 200wpc 400 wpc. Actual: 290 wpc 350 wpc. It's a good amp if you like that sort of forward sound and have great sources.

Just realize that all this talk of doubling down the power to drive speakers has wrinkles. And frankly I don't see how it affects the speaker output as long as the amp isn't being driven hard. If the amp can deliver the current that's drawn across the impedance across the frequency range then what's the problem? Of course an amp has to deliver more at 4 ohms but up until the limit of the amp is reached it should do that without affecting the sound.

I'm not disagreeing with your discussion of low output impedance. However, in rereading Harley's discussion of power output into varying impedance loads, and the resulting loudspeakers' varying dbW (decibel watts) measurements, he makes no mention of low output impedance negating the effect. Perhaps this is an issue of voltage paradigm versus current paradigm?

I don't have Harley's book, and so I don't know exactly what he is saying, but yes the question can be considered in the context of the two paradigms of amplifier and speaker design. Those being the voltage paradigm, and the power paradigm, which is more accurate terminology than "current" paradigm, as explained in Ralph's (Atmasphere's) excellent paper on the two paradigms.

Consider the output stage of an amplifier to be a theoretically ideal voltage source (zero output impedance), the voltage being proportional to the amplifier's input voltage, in series with a resistor (equal to the amplifier's output impedance).

In a voltage paradigm amplifier, by definition, the value of that resistor approaches zero (i.e., it will be a small fraction of an ohm). The result is that the speaker will see a voltage proportional to the amplifier's input voltage, regardless of what the speaker's impedance may be at the frequency that is involved (as long as the amplifier is capable of supplying the required current, the required current being higher as the speaker's impedance decreases -- recall Ohm's Law). Nearly all amplifiers with solid state output stages work this way, and the majority of conventional box speakers are designed based on the assumption that they will be driven this way. Many tube amplifiers approach this model, although only approximately because their output impedance is typically higher. Other tube amplifier's, with even higher output impedances, fall into the power paradigm category.

As Ralph's paper mentions, a significant downside of voltage paradigm amplifiers is that they typically (but certainly not always) require more feedback than power paradigm amplifiers, increasing the well-known side-effects of feedback.

In a power paradigm amplifier, the output impedance is much higher, for instance 4 ohms or more in the case of many of Ralph's designs. That will cause both the voltage that is seen by the speaker and the current that is drawn by the speaker to depend on the impedance of the speaker at the particular frequency that is present. The higher the speaker's impedance at the particular frequency (or frequencies), the more voltage it will see (because it represents a greater fraction of the total impedance that is in the path, meaning its own impedance plus the amplifier's output impedance), but the less the current that will flow (because the total impedance in the path is greater). Since, if we neglect the effects of inductance and capacitance, power is equal to voltage times current, the power that is delivered to the speaker (as opposed to the voltage) will remain fairly constant as a function of variations in the speaker impedance.

As I said, most speakers, especially box-type speakers, are designed with the expectation that they will be driven with voltage-paradigm amplifiers. But Ralph's paper includes this statement:

Loudspeakers that operate under Power Paradigm rules are speakers that expect constant power, regardless of their impedance. Examples include nearly all horns, ESLs, magnetic planers, a good number of bass reflex and acoustic suspension designs. Horns, ESLs and magnetic planers do not get their impedance curve from system resonance and so benefit from a constant power characteristic and indeed, many of these speaker technologies are well-known to sound right with Power Paradigm amplifier designs.

So that is some background. Returning to the original question, I think all of this should make clear that a tonal imbalance can result from a paradigm mismatch between amplifier and speaker, such as the excessive brightness that would undoubtedly result from using a power paradigm amplifier (high output impedance) to drive this particular speaker (4 ohm impedance in the bass, 8 ohm impedance in the treble). But a voltage paradigm amplifier (near zero output impedance) would deliver essentially the same voltage into both the 4 ohm and 8 ohm impedances, which is presumably the expectation the speaker was designed based upon (or it would not sound right with just about any solid state amplifier). And the ability of the amplifier to deliver twice as much current into 4 ohms than into 8 ohms has no direct relevance to tonal balance; its main relevance is to maximum volume capability. Although, of course, for any of many other possible reasons one voltage paradigm amplifier may sound different with the particular speaker than another, and it stands to reason that an amplifier that can double current into 4 ohms will, everything else being equal (which of course they rarely are), be more comfortable dealing with a speaker like this.

I'll add in closing that although I haven't read Harley's book, I have read a lot of his writings over the years in TAS and Stereophile, and I suggest that you do not exclude the possibility that anything he says of a technical nature may be flat-out wrong.

Best,
-- Al

Al,

I suggest that you do not exclude the possibility that anything he says of a technical nature may be flat-out wrong.

Best,
-- Al
Almarg (Answers)

On the other hand, we can also not exclude the possibility that he is right. In the acknowledgments section of his book, Harley thanks several experts in specific fields of audio who provided technical review of his manuscript. I am going to take the viewpoint that they know their fields, and that therefore the information provided in the book has been determined to be correct.

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Blindjim,

TVAD
My statement regarding your truncated list of options is quite valid, nonetheless. It didn’t contain all of the avenues listed herein to that point…. Merely those paths and people you felt were more appropriate to the mix.

The list was intended to illustrate the wide range of suggestions to one problem. It was not intended as a comprehensive resource. I did not intentionally include only the avenues I felt were appropriate in an attempt to diminish the contributions of others, as you suggest.

I agree with you in general about restocking fees. It's up to each individual to decide if the cost of shipping and a possible re-stocking fee is worth the price of an in-home trial. I believe there's no substitute for listening to a component in one's system prior to buying, so for me the cost of shipping and a restocking fee can be worthwhile. When I had the opportunity to home-trial the Pass Labs XA-30.5 amplifier, I gladly agreed to accept a possible 10% restocking fee in the event of a return. For me, the ability to hear what that amp could do in my system was well worth the price of admission.

My present ownership of Pass Labs, SMc Audio, and my prior ownership of Moscode products were all results of in-home trials. In-home trials have also afforded me the opportunity to audition Audio Horizons, NuForce, and CI Audio products. Only CI Audio, and the Pass Labs dealer charged a re-stocking fee, and I paid it in both instances (the XA-30.5 was returned because a used pair of XA-60.5 became available during the third week of the demo).

The Portal Panache is available with a *60* day home trial, and there is no restocking fee mentioned on the Portal Audio home audition policy page. While there are no specifics of the Ice H20 Audio home audition policy on the H20 Audio website, I doubt Henry Ho (owner of Ice H20 Audio) would charge a restocking fee. He's happy to have more people hear his components.

Those who believe the cost of shipping and restocking is too high to allow experimentation should definitely look at other alternatives.

There is no sure-fire, cost-free method to solving the OP's brightness problem (the most common complaint in Audiogon threads). If there was, we'd all be doing just that one thing and these threads would be really, really short.

Again, thank you for all your input and your time doing it. Blindjim, The situation with me and my gear is this. Several months ago, maybe 6, I decided to get back into the hobby. I had an old NAD preamp tuner and a cheap audiosource amp3. I still had my KEF 103/4 speakers from 20 years earlier and decided to buy everthing new (to me). I started reading the forums here and several audio reviews to try adn decide what I should buy. I know this isn't the best way to put a system together, but we just don't have the retail stores around here in Seattle like we used to. And, although I grew up here and have many friends I don't have a single one that's cares about gear or music for that matter. This is why after several months of listening to my system and continuing to read what many of you have to say on these forums I decided to reach out and ask for help. I will say that I did not have the brightness problem with my old set up. That being said, the system was very closed in and I'd say even muffled to some degree. I can say one observation is that I did play my NAD with the Butler amp and also my surround sound Denon 990 and the system was not bright. But it was also very closed in without a lot of detail and the Denon just sounded bad. When I added the Capri which was slightly used it also seemed closed in. Then after a couple of weeks bam! While I was listening it just completly opened up. That's when the brightness started. So much for me not believing componants break in. Yes, the sytem is brighter, but I can hear everything now like a veil was lifted. So, my thinking is that any quality pre would probably do the same thing.
I do listen to my system pretty loud around 70 to 95db depending on my mood and the music I'm playing or how much I've had to drink :). And yes, I do have to turn up the system to get the speakers to fill the room, otherwise the music just feels like it's not forward or engaging enough. I've thought about a sub and also wondered what another speaker that dives a little deaper in the base might do for me (Aerial 10T?). I expected the 7B to do the job, but they seem to mostly do a really good job at tight fast base which I do like. TVAD, I've been contemplating raising my speakers up already, but for a different reason. Mabe I can solve two problems at the same time. The ends of my two identical couches are very close to the front of the speakers and yes, this does effect the base to some degree. I've moved the couchs out of the way along with my coffee table and know what the differences are so I didn't bring that into the mix here. That is not the heart of the problem. When lifting my speakers up, are there some general rules to follow? Do I use wood covered in carpet, concrete, how high do I lift them ect? I really do want to get to the bottom of this, I hate a bright system. I'd rather go the other way and lose a "little" detail. Thank You All Again!

When lifting my speakers up, are there some general rules to follow? Do I use wood covered in carpet, concrete, how high do I lift them ect?
Gregfisk (Answers)

You'll receive a lot of good suggestions and techniques to try.

I have used 1" threaded, brass spike footers, Sistrum SP-101 platforms that allow height adjustment from about 1" to nearly 8", and presently I use 2" thick maple platforms flat on the carpet and with no spikes on the speakers. In my room with my nearfield listening position, raising the speakers by 2" has proven beneficial, and simply raising the speakers seems to have made a more consistently positive difference than has the type of device used to raise them.