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HF81 on the Scope 20Hz to 20Khz


NOSValves

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What model do you have, Tony? Old vintage or new? I have owned a few 72 BMWs and they ranked as some of my favorite cars. This preceeded the "yuppie" connotations attached in the 80s... It's a great marque despite a few ups and downs. That original 6 of theres was an all time great engine.

My two sh!tboxes....

http://www.progressive-engineering.com/klipsch/stable.jpg

kh

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new....330i...it was my mother-in-law's...she thought it too much to handle so...I had to take it off her hands...lol, nice ride...though down here you are much better off with 4X4 SUVs, I use the Pathfinder most of hte time and the bimmer for a sunday cruise around town...tony

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Oh no, that's a terrible idea.

I suggest someone send in a "good" sounding one instead. Test it, compare to the other, and post the results.

Paul, if it "feels" faster, then it "is" faster. Perception is everything, and probably doesn't just involve the ears.

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If you remove the upper harmonics from a square wave, with no phase skew or amplitude degradation of the remaining harmonics, you get something that looks like overshoot at the start and end of each pulse, and some ripples in between. A smooth, no-overshoot approach at each transition, is indicative of phase and amplitude deviations of the upper harmonics included. If your amp is good out to 100KHz, maybe that doesn't matter. Still, smooth, no-overshoot approach at each transition makes a good time-domain picture, and is also good for video transitions, but in a bandwidth limited situation, such as a transformer-coupled amplifier, it may not be as good as it looks.

The nature of impact that analog electrical components have on a time domain signal is called "causal." That means they take place only after an event (such as a voltage transition) has taken place. A causal system cannot produce a perfect bandpassed square wave. However, one with some wide bandwidth overshoot (possibly critically damped) may make more sense in the frequency domain (where we hear) than one that is overdamped as the smooth approach is technically called.

A nice overdamped amplifier is a technical achievement, and if it has a very wide bandwidth, it probably sounds great. However, in a more bandwidth limited situation, I would bet that people would find some overshoot sounds more natural .. and I think it is technically reasonable.

By the way, digital systems can implement non-causal systems (filters that impact the sound before it happens), and most cd players implement them. It's done with a pipeline structure that has half of its elements in what is technically negative time. Such a filter will produce a square wave that has what looks like overshoot at the start and end of each pulse, and some ripples in between.

no easy answers folks.

leok

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On 11/6/2003 11:56:07 AM mdeneen wrote:

I'm a bit surprised at the negativity expressed toward Craig for posting this "data." Well, more than surprised, it bewilders me. I'm always a bit non-plussed when people involved in a highly technical pursuit (depending wholly on the proper operation of physics) get defensive about 'data."

The best thing that could happen now, is for some of the EICO afficiandos, who know the sound of these units inside and out, to listen to THIS unit and report back whether it is one of the "good" sounding ones, or the "bad" sounding ones. This would allow for some crucial understanding of those sonic preferences. I doubt this will happen though.

mdeneen

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Not too sure if you are refering to me here...

In case it's me I think I summerized earlier in this thread in some lines what you wrote in a much more detailed fashion. At no point I did say measurements were useless, only that they do not tell the whole story.

I prefer to come up with a simpler "in case of inconsistencies between what you see and what you hear, trust your ears over the scope". Other will choose to come up with some esoteric explanations like the MSc Thesis I once posted a link to trying to explain why SET are superior to PP amps. This kind of "measurement twisting" in order to prove a pet theory is not helping objectivity in amp measurement (besides I just do not buy the concept than one topology is inherently superior to another). And this for me is much more "fairy dust" than a simple "I don't know but sit here and listen".

As for the Eico measurement project. Craig and Ryan are the best person to do it. I personally do not recommend any vintage amps to my immediate entourage as they always lend on my bench for repair before these can be used. I just don't have the patience to work with these old things. Craig and Ryan should see enough of them to gather a meaningful and useful database on Eico, Scott, etc. (measured as is, after parts replacement and after tuning).

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On 11/6/2003 11:36:01 AM rtaylor wrote:

.... Jazman is a very angry man about something.
11.gif
I hope he gets better. Randy

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Randy,

Are you having a hard time with the truth? Craig's past remarks in his continuing "Scott is beter than Eico" pursuits, and the comment I cited from the other post is what started this post by him. As usual, his agenda is very transparent. I don't know where you get anything "angry" from my post. It's simply amazing to me that when BS is being spread around by him, people like you can't smell it, or just don't want to. I do not gain one penny if a person buys a Scott or buys an Eico. It's simply time for Craig to stop pushing his cash cows, and if someone finds an Eico's sonics superior to a Scott, so be it. The same goes for someone who prefers a Scott over an Eico. There seem to be enough who like them that he does not need to go through these measurement gymnastics. Measurements in audio can be indicators, but not the final word in how something sounds. I can think of at least one European mag that doesn't publish measurements with it reviews. And Randy, Have a nice day.

Klipsch out.

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"At no point I did say measurements were useless, only that they do not tell the whole story."

Duh! Why does this OBVIOUS point have to even be made over and over and over by so many here. It is obvious that those who look at the physics also have ears, they are ADDING this information to what EVERYONE including themselves can experience in their own subjective way. IT GOES WITHOUT SAYING and only belies some insecurity that some hardcore "mystics" have about their traumas in school with math and science. Give it a rest, we all know that numbers don't absolutely predict subjective response, it doesnt need to be said anymore and the implication that those who can handle numbers are somehow deficient in the subjective area is totally bogus and insulting.

Facts are uselful in audio and politics.

C&S

 

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I have noticed many participants in this forum who have what might be interpreted as "vested" interests possibly connected to some aspect of their livlihood. Personally I have absolutely no problem wlith this. I was grateful to have my "bad" Eico HF-81 converted into a "good" one by Craig, learned a bunch about crossovers from Al, and have been led to numerous informative websites designed by others who participate here. I have seen many grab some good deals offered by sellers of equipment. I don't see any problem really, given that we all can decide for ourselves of what to partake . I don't see anyone in this regard any more "transparent" than anyone else. By far the most useless and energy draining is flaming those we disagree with, but we are all human and this seems to be inevitble occasionally, and have been guilty myself, when I forget to take the meds. Or is it when I do take the meds....I forget....

Just my opinion.

C&S

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Hi Jazman,

Here is hoping you're having a good day also.

No, I believe that the truth is self evident. Some people have an axe to grind and maybe you are one of them. I'm not a shrink and don't profess to be but your words do lead me to believe that you are angry about something. You seem to go off for no apparent reason alot. Again, just my opinion and sorry if I have offended you somehow.

Randy

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On 11/6/2003 2:39:50 PM Clipped and Shorn wrote:

Duh! Why does this OBVIOUS point have to even be made over and over and over by so many here. It is obvious that those who look at the physics also have ears, they are ADDING this information to what EVERYONE including themselves can experience in their own subjective way. IT GOES WITHOUT SAYING and only belies some insecurity that some hardcore "mystics" have about their traumas in school with math and science. Give it a rest, we all know that numbers don't absolutely predict subjective response, it doesnt need to be said anymore and the implication that those who can handle numbers are somehow deficient in the subjective area is totally bogus and insulting.

Facts are uselful in audio and politics.

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For your information, I just finished writing my PhD thesis draft on discrete numerical modelling of gravity flow in ore passes. Mathematics and physics are not much of an enormous problem for me. Though I'll confess Laplace transformations and Fuzzy sets always got me in trouble trouble in my maths courses.

I think what is deficient here is your ability to read (or my english is that poor). Where the heck did I say that anything that implies that "those who can handle numbers are somehow deficient in the subjective area". Don't put words I haven't said into my mouth.

Having a bad day at the job or what?

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