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Learning oppurtunities...

So I like to think I always learn something as I go, with each project. As an example, the recently completed DSA175 project. While the woofer is not the best sounding driver - it is an obvious improvement from the paper cone version. The specific learning moment was noting the reduction in distortion due to the metal cone, the shorting ring, or both. 

The impedance curve does not indicate the presence of a shorting ring - but there are other ways of lowering distortion and I suspect the shorting ring was doing its job regardless of noticing it on the impedance sweep. I also feel the aluminum cone contributes to the reduction in distortion between the paper and aluminum cone versions. I consider it a learning moment because we are generally conditioned to correlate the shape of the impedance curve with an expected distortion profile and this is not always the case. 

So what say you? What have you recently learned or realized or had affirmed?
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MzissersonJasonPkennykD1PP1N

Comments

  •      Despite (Channing! ;)) reading it in a couple of different places, I finally succumed to the fact that errors in the T/s parameters of 20%-30% from the mfg data typically amount to a hill of beans regarding cabinet design.  This was after looking at the DA115's I just measured and again having mfg. Data be somewhat off.  In fact, save for the real high quality drivers, most are off in some form or another by at least 10%-20% in one form or another. I have never come a cross a driver that was SO far out of whack I needed to mod the cab, or change tuning. 

    The shape and anomlies in the Z curve are far more important, as or the rest of the measurements once in cab. 
    greywardenJasonPkennyk
  • I often hear that sibilance is caused by the woofer breakup not being pushed down enough.  I agree, but on a recent project I couldn't get the S sound to go away.  I finally traced it to the ND28F tweeter.  I was asking the tweeter to play a lower than 2K.


    So my learning or reaffirmation was to remember to listen to the drivers individually if possible.


    I had learned that earlier with the Mini PT planer tweeter, but some how discounted that learning with a 28 mm dome tweeter.

    JasonPkennyk
     John H, btw forum has decided I don't get emails
  • My very very first build, I learned that it's not easy to learn how to build speakers. It was with Dayton Euro series woofers, Peerless tweeters from the same era, and never even bought the premade crossovers, didn't finish building them, and told my dad to just drop the drivers off at the goodwill.

    Second build a few years later, I bought measuring equipment and did 4-5 different versions of the enclosure, finally settled on a fully active setup with MiniDSP. That was the deadhorse. Great drivers, "meh" sound with lots of boxes left unticked in the fully active department. 

    Next build was the Leviathans, I learned a lot about building large enclosures and finishing in this build. I forgot to use filler on the subwoofer box butt joints, and it's night and day between the two. These were also fully active - what a huge waste of money on cables, DSP and Amps. Sounded "good" and flat to 13Hz, but not exactly a flawless design. 

    Next was the Harbingers, did some "precision" work with real wood in this build, as well as my first passive crossover speaker, marked improvement on measurements, construction, damping, etc. on this build. Great sound, great off-axis FR, too. The finish was intentionally flawed and looked great. FWIW I really prefer passive crossover speakers. 

    WIP is the Shockwaves doing a 3-way with a coaxial driver and a passive radiator as well. These will have passive crossovers and be nearly full-range for music. Also, they have a constrained layer panel enclosure. I'm wanting to make some distortion measurements on these and I want them to have great off-axis performance like the Harbingers did. 

    Next build isn't really planned, but if the coaxial thing works, I want to build another 3-way coaxial with a veneered, constrained layer, passive crossover, <35Hz F3, and great off axis FR. Maybe even powered with diy amps? With every build I try to focus on learning a new aspect of the hobby.
    JasonP
    deadhorse - leviathan - harbinger - shockwave (wip)
  • I often hear that sibilance is caused by the woofer breakup not being pushed down enough.  I agree, but on a recent project I couldn't get the S sound to go away.  I finally traced it to the ND28F tweeter.  I was asking the tweeter to play a lower than 2K.


    So my learning or reaffirmation was to remember to listen to the drivers individually if possible.


    I had learned that earlier with the Mini PT planer tweeter, but some how discounted that learning with a 28 mm dome tweeter.

    Good stuff! 
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  •      Despite (Channing! ;)) reading it in a couple of different places, I finally succumed to the fact that errors in the T/s parameters of 20%-30% from the mfg data typically amount to a hill of beans regarding cabinet design.  This was after looking at the DA115's I just measured and again having mfg. Data be somewhat off.  In fact, save for the real high quality drivers, most are off in some form or another by at least 10%-20% in one form or another. I have never come a cross a driver that was SO far out of whack I needed to mod the cab, or change tuning. 

    The shape and anomlies in the Z curve are far more important, as or the rest of the measurements once in cab. 
    I generally agree with this - but the Aurum Cantus drivers I bought were so far off of mfr data (and each other) that they were unusable in pairs. 1-1/2db difference in sensitivity, despite modeling similarly in the bottom end. 

    Taught me a valuable lesson about the oft-repeated "modeling shows a similar F3, you will be alright" mantra. Something has to give when two drivers with wildly varying T/S parameters model with a similar F3. 

    I am willing to accept 1/2db difference in sensitivity - but 1-1/2db is pretty excessive for unit to unit. 

    That being said, other than those AC units, it has been awhile since I have come across any other drivers with outright bullshit advertised specifications. In fact, I am consistently surprised at the level of QC in even cheap drivers these days. 
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  • jr@mac said:
         Despite (Channing! ;)) reading it in a couple of different places, I finally succumed to the fact that errors in the T/s parameters of 20%-30% from the mfg data typically amount to a hill of beans regarding cabinet design.  This was after looking at the DA115's I just measured and again having mfg. Data be somewhat off.  In fact, save for the real high quality drivers, most are off in some form or another by at least 10%-20% in one form or another. I have never come a cross a driver that was SO far out of whack I needed to mod the cab, or change tuning. 

    The shape and anomlies in the Z curve are far more important, as or the rest of the measurements once in cab. 
    I generally agree with this - but the Aurum Cantus drivers I bought were so far off of mfr data (and each other) that they were unusable in pairs. 1-1/2db difference in sensitivity, despite modeling similarly in the bottom end. 

    Taught me a valuable lesson about the oft-repeated "modeling shows a similar F3, you will be alright" mantra. Something has to give when two drivers with wildly varying T/S parameters model with a similar F3. 

    I am willing to accept 1/2db difference in sensitivity - but 1-1/2db is pretty excessive for unit to unit. 

    That being said, other than those AC units, it has been awhile since I have come across any other drivers with outright bullshit advertised specifications. In fact, I am consistently surprised at the level of QC in even cheap drivers these days. 
    Even where displacement limited? I guess thats only part of the picture and could be the reason sims dont change much.  Makes me think that 1-1/2 could be a big issue in the pass-band though. 

    I heard a while back (may have been from you)  that AC drivers were paticularly bad. Scary at the beads and trinkets traded for them. 
  • I for sure learn something new every build. Weather it be a tip for the x-over design, or learning to measure 3 times and cut once, or writing down my game plan for the build before even thinking about cutting any wood. Probably the biggest thing I have learned, especially with this last build is to NOT RUSH ANYTHING! I am an instant gratification kind of guy - hate waiting to see how something turns out and it shows in some of my earlier builds for sure. But I took my time with this last build and didn't rush any steps and I am very happy with how it turned out. Plus I couldn't afford to screw up my piece of wood that I used ;)  
  • Patience. This last year I built a lot of speakers and not one set for myself. I allowed myself to get rushed, set difficult to accomplish deadlines and my family paid for it. That won't happen again. 
    JasonPduanebro
  • Patience. This last year I built a lot of speakers and not one set for myself. I allowed myself to get rushed, set difficult to accomplish deadlines and my family paid for it. That won't happen again. 
    This is a big one I didnt grasp until.about 2 years ago. You are making something that will last 30+ years. The extra time to tie everything up tight is worth it. 
  • Patience is indeed a virtue.
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  • I learned from the thread "over there" that nobody's dream build uses Dayton, MCM, or buyout drivers LOL.
    jhollanderJasonP
  • I have a dream build in mind (and early planning) that uses Radio Shack drivers, so that's something.

    I am also thinking of doing a dream build with all MCM drivers because I suspect the new KB will be good enough to qualify as high end.
    PaulCarmody
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  • jr@mac said:
    I have a dream build in mind (and early planning) that uses Radio Shack drivers, so that's something.

    I am also thinking of doing a dream build with all MCM drivers because I suspect the new KB will be good enough to qualify as high end.
    I'm right there with you. 

    I try to learn something new with each build. Whether it's in the drivers, crossover, cabinets, etc. I've learned to expect consistency with Dayton woofs, but not necessarily great sound. 

    I've learned or tried to at least improve on taking criticism  (constructive and otherwise). That helped me enjoy this hobby again. 


  • I've learned or tried to at least improve on taking criticism  (constructive and otherwise). That helped me enjoy this hobby again. 


    Seems hard to give constructive criticism via the internet.  Few people assume positive intent.

    I'm guilty as well assuming people are not being helpful.  Seems like the new criticism is ignoring.

     John H, btw forum has decided I don't get emails
  • I've learned or tried to at least improve on taking criticism  (constructive and otherwise). That helped me enjoy this hobby again. 


    Seems hard to give constructive criticism via the internet.  Few people assume positive intent.

    I'm guilty as well assuming people are not being helpful.  Seems like the new criticism is ignoring.

    The problem with criticism is I have seen (anf had try on me) people get buried because they are breaking some rule a sacred cow set forth that has ground, but is not the only way you can do something. How knowledge is applied is as, sometimes more, important than quantity of knowledge and there is ZERO rwspect for that. Or the fact that we are a loudapeaker's iterface, NOT another peice of electronics. 

    Sugguestions are great, and I have learned a lot from MANY, even from "noobs" who see things with fresh eyes, but to tell someone they are wrong when they are simply different can be the cause of many issues. 

    The science is the science. Period. How we apply and use it....Well, that's the rub. 
  • I've learned or tried to at least improve on taking criticism  (constructive and otherwise). That helped me enjoy this hobby again. 


    Seems hard to give constructive criticism via the internet.  Few people assume positive intent.

    I'm guilty as well assuming people are not being helpful.  Seems like the new criticism is ignoring.

    Absolutely John. I try to give all the benefit of the doubt. Those I know on a more personal level, I enjoy getting feedback from. Some others, not so much lol
    jhollander
  • I think the one way, blind feedback system such as the internet can definitely be tricky to learn - from both sides of the issue. 

    "If it were me, I would have tanked the breakup and tuned it lower"

    "Not tanking the breakup and tuning it so high is a mistake"

    "In some cases, otherwise unexplained hiss and/or overall impression of brightness can be attributed to untamed breakups or not tuning deep enough"

    All three are different ways of telling someone they may have made a mistake - all three are well intentioned but almost impossible to receive easily due to some massive assumptions made on the part of the critic. 

    Perhaps a better way is to lead off with "How did the overall tonal balance sound relative to some other speakers you have listened to?" - and pursue it further if the designer says something like "Kind of bright - but the tweeter level measures pretty much in line with the mid".

    I no longer really listen to that type of feedback, and I rarely offer that type of feedback any more unless directly asked to do so by someone. There is nothing to be gained by publicly proclaiming someones design to be a piece of shit - in DIY that is. I figure commercial guys are open game, for the same reason McDonald's is open game and movie studios are open game and pop singers are open game. 

    The above being said, the type of feedback that drives me up a wall is... "Crossover needs better integration" or "Can't quite put my finger on it, but it seems like the bass is slow" or "I feel like there are some notes rounded off in the 3kHz region" or other such nonsense. Absent knowledge of said crossover and expanding on the particular issue and offering specific advice intended to correct any perceived issues - that advice is absolutely meaningless, and does nothing but make the critic sound a bit pompous. 

    Ultimately, I guess I am fairly jaded these days in that I suspect a lot of people with very public opinions on audio in general just have an urge to beat people up. When I make comments like "Led Zeppelin" is over-rated, I receive a lot of shit from people who, you would think based on their comments, must believe I personally consider people who like Led Zeppelin (which I do - they are just over rated) to be pieces of shit. Like - if I said Justin Bieber is a piece of shit, I would get high-fives and hell yeahs from the crowd. Never let people tell you the hive mind does not exist in all areas of life. 

    So I guess what I have learned over the years is that telling someone their god isn't real is or their taste is inferior is just asshole behavior. There are ways to lead into constructive criticism, and the one-way blind nature of the internet, unfortunately, makes it difficult to convey criticism without coming across an ass. 

    TL;DR telling someone their speaker should be shit because of something they did you disagree with or telling someone their speaker is shit without offering advice and support makes you an asshole, whether intentional or not. 
    jhollanderJasonPD1PP1N
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  • edited October 2016
    One of the most surprising learning opportunities was a post a guy did on HTGuide years ago... I really wish I could find the thread.  He made lots of sample song files where he would rotate the phase 180, 360, 540, etc degrees at 2000 Hz (to simulate crossover orders).  He didn't tell which files were which with regards to phase rotation; you had to guess. 

    I tried multiple ways, with multiple speakers and headphones, and couldn't hear a difference on any of them. The only way I was able to finally tell the difference was to run them through the Liberty Audio DiffMaker program. 

    It was proven to me then that this whole obsession about "linear phase" or amount of phase rotation at the crossover point just is not audible--to me, anyway.  And don't get me wrong, it's not that I'm going to go out there and slap 1st order crossovers out of people's hands... if achieving perfect time alignment and linear phase is an exciting design goal for you, have at it.  But it was a relief for me that I didn't have to worry so much about it, or time aligning drivers to achieve perfect phase coherence was going to make an audible difference in the final product. 

    Again, I REALLY wish I could find that thread.  If anyone has it, or can find it, PLEASE SHARE.
    FaceJasonP
  • PaulCarmody said:

    Again, I REALLY wish I could find that thread.  If anyone has it, or can find it, PLEASE SHARE.
    Here you go: http://www.htguide.com/forum/showthread.php?t=32280

    jr@macJasonPS7910kennyk
  • Face said:
    PaulCarmody said:

    Again, I REALLY wish I could find that thread.  If anyone has it, or can find it, PLEASE SHARE.
    Here you go: http://www.htguide.com/forum/showthread.php?t=32280

    You da man!
  • Something I learned a few builds ago is that "works on paper" and "works in practice" don't always go hand in hand. Stuff that looked like it should play nice together didn't and a planned TMWW is going WTW because the M isn't actually needed unless chasing power handling.
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