I've explained the background to my question a few times, no problem, I know it was a general question, I wasn't after a one size fits all answer from you, it was to start a discussion about the real relevance of square waves once they are launched into the room.
what has been alluded to by myself which is snake oil? Lets clear it up.
THx-RNMarsh
Now we are narrowing down your question...
Keeping intact a sq wave can be done a couple ways after launched from the driver(s).... near-field listening and related is a narrow, controlled dispersion speaker.
Neither it sounds like you are doing. Listening in far field... back into the room will have serious affects on the waveform. This I assume you know and see on the scope.
So, in order to have any meaning of accuracy you have to keep the acoustic signal intact -- without reflections, etal interfering all the way to your ears. otherwise, you are listening to corrupted waveform... which can be pleasant and likeable, but not accurate. I always recommend listening in near-field only.
The point then depends on what you wish for.
THx-RNMarsh
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Basically yes. Without filler, any transient perfect XO with at least one slope (acoustically, electrical is irrelevant) steeper than 6dB always has peaking (which means destructive summing) and overlap, one can trade one for the other, though. At least with conventional techniques, the woofer and tweeter diaphragms aligned in the same plane, and no allpasses used. A most general statement is that any transient perfect XO of this kind always has non-zero phase offset, which means they can only be used, if at all, for symmetric W-T-W designs or coaxials.
Once driver offsets and group-delay compensation allpasses are factored in, things change. It then is possible to have something like 4th order slopes with tracking phases throughout the XO region, no peaking, and summed response with zero phase. See here, for example.
At this point circuitry and design process get truly complicated. Today it makes zero sense to strive for linear phase speakers (and compromise other aspects of speaker design) with analog means when it's so trivial to apply an overall phase-correction to the playback source. Assume you have a Linkwitz-Riley-XO at 2kHz, just calculate its phase response (no need to use measured data as that introduces unneccessary errors, rather use curve-fitting), invert it in time, and stuff it into a convolver plugin, done.
I never said you had. I asked for an example of someone's 'experience' being ignored for theory. I was just pointing out ignoring someone because they are spouting audiophool BS is not the same. There is still data on one side and buckets of anecdote on the other. Lots of anecdotes does not make data.
yes. we know and all here agree about this....
I may debate that careful experience can be useful data as well.
But, I know what you are looking for which qualifies for Data.
I tried to illustrate why LLNL only hires the most experienced EEs.
I can give many real world examples of things going awry by in-experienced but otherwise bright EEs.
I had to watch a wonderful young bright EE get let go from LLNL for costly mistake which a more experienced EE would not have made...... he asked me if it was going to end his career... I said probably. [he didnt work for me] A reminder to management Not to hire inexperienced EEs for high risk, high cost projects.
-Richard
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I am sure LLNL also hires graduates and fresh PhDs and trains them up, but that is not the point. I'm just not sure I've seen real experience being ignored. Howie isn't ignored, Ed when he isn't being silly isn't etc.
Keyboard warrior opamp rollers on the other hand I do not consider as 'experience'
Keyboard warrior opamp rollers on the other hand I do not consider as 'experience'
Silly?
How else is one expected to treat the arrogance and ignorance around here?
BTY can you reproduce square waves in a non rectangular room, such as one that has curved walls?
(Actually a comment on some theories of acoustic design!)
They have mentor summer programs. No they otherwise dont hire them. Only senior experienced people. Not limited to USA hire. Just find the best in the field and pay what ever it takes to get them.
A top 1 percenter PHd could come in as a junior scientist and work for a senior scientist on his project if his speiality matched the needs. This occasionally happens. Very rarely. It is not a teaching place. My point is, experience matters, too. lets all try to respect that.
But, why are you pointing out such things as opamp rollers? and the like? We keep hearing Snake Oil sales men etc. Did something here trigger that? Why does that keep coming up?
Thx-RNMarsh
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Could you please answer my question or give a link
John Curl's Blowtorch preamplifier part IV
Even better would be if you could show your FR measurement before and after having adjusted the AC line voltage that you mention.
Sorry for the "annoyance of being questioned" to quote Chris719
Hans
FWIW, this thread has just has appended an LR4 crossover with a "filler driver" option that allows instant switching between the "transient perfect" and otherwise optimal LR4 alignments so you can hear for yourselves that it is probably not worth the effort 🙂 There are better means to provide phase linearisation as and when there is a benefit...
PASSIVE Linear Phase (Quasi Transient Perfect) XO s
PASSIVE Linear Phase (Quasi Transient Perfect) XO s
Sorry, no I cant. I missed your question somehow... I dont do my experiments for the benefit of others so i dont usually document it. Lately, I have started to do so because of this DIYAudio who ask for such info. I still have the ESL in a storage room over here. So, its a remote possibility i could do it again. I have never seen anyone discuss this before. Maybe tell an ESL DIY group who has such current interest to do it?
The speaker has leakage..... it 'should' have a long time constant so i dont know why it was happening other than increased leakage... It was in LA near the ocean. ?? Humidity affects these speakers a lot with increased leakage. The problem is worse in Bangkok. I can now hear the leakage hissing in Bangkok. Have to tear into it and see what can be done or sell them to an Arab country (dry). Its a real issue with ESL speakers. Humidity/leakage/HF roll-off.
THx-RNMarsh
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I was just qualifying so we understood what 'experience' meant in preparation for you giving an example of it being ignored in favour of half a theory.
We are on the same page so ready for the example.
hahaha OK Right. Ignored.. .. maybe experience is discounted is more what I had in mind.
I am going to look up How-To quantify experience..
-Richard
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I've auditioned once a LS built according this principle and the sound reproduction was quite pleasing.
So now I took the time to read the paper from the above link carefully and must conclude that I overestimated the benefits.
But this crossover world is obviously not my thing and I don't have to bother with my ESL's.
Hans
Actually it happens quite often (in various degrees, though).
Think about experience when it comes to controlled sensory experiments (obvioulsy, it doesn't matter even if it is backed up by scientific evidence)
Reports about controlled listening with results contradicting the "usual" wisdom about possible audibilty are routinely ignored or - if the personal animosity kicks in - the trash talk starts.
You know, total crap, wrong people, hidden agendas, wrong journal, nonqualified reviewers, paid by the wrong sponsor; whatever is thinkable will be brought up (I've listed some parts ofit already in the past).
If you are referring to the to the ESL, it would exactly show whether the FR is dependent on the AC Voltage level.
If so, it could be the start of further investigation to find out why and what effect this might have on audible sound reproduction.
Hans
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