Agreed; it looks a conflation of 'submultiple' / submultiples of x frequency, so as you say, strictly speaking not the right term, although probably 'near enough' to get the general point over. It's not always easy though, especially if English isn't the first language -as I say, I guess all we can do is try to be as clear as possible about what we're describing, so any slips in technical language don't affect the basic theme.
+1. If the baseline motor linearity is sufficient to ensure the HD peaks are low enough not to be audible at the maximum intended drive level, it's a non-issue. Good enough is good enough. 😉 Unfortunately, it often isn't -unless you've got a heck of a good motor, and / or are able to cross below the first big HD peak, and the former usually (not always, but usually) in my experience means a driver selling for a fairly 'serious' price tag.
As a long time user of SEAS Alu cones, I can say from experience a parallel LC is imperative regardless of xo frequency or slope.
If you don't, as well as not having a flat roll off, you will: not dampen distortion enough, which will lead to artefacts such as a hardness on upper notes of piano for example; it will also impact the phase response making the sound less open.
Once tamed, the L series cones have some of the smoothest responses out there, and, a great sound too.
If you don't, as well as not having a flat roll off, you will: not dampen distortion enough, which will lead to artefacts such as a hardness on upper notes of piano for example; it will also impact the phase response making the sound less open.
Once tamed, the L series cones have some of the smoothest responses out there, and, a great sound too.
I like the 8 ohm L15RLY/P in my 3 way speakers. The tweeter is definitely the weakest link here.
I found I could get away with a XO point of 2300 - steep slope (LR4+), before the HD3 2700Hz breakup (induced from the 8100Hz primary mode) was a problem.
Attached are 2 graphs, one with the raw driver and one with both parallel and series notches. I'll post the notches separately. Of course, impedance will change values for your 4 ohm version
Notice with the XO, the HD peaks are reduced, but still there:
Double whammy - notch overkill:
I found I could get away with a XO point of 2300 - steep slope (LR4+), before the HD3 2700Hz breakup (induced from the 8100Hz primary mode) was a problem.
Attached are 2 graphs, one with the raw driver and one with both parallel and series notches. I'll post the notches separately. Of course, impedance will change values for your 4 ohm version
Notice with the XO, the HD peaks are reduced, but still there:
Double whammy - notch overkill:
AllenB> I have heard a metal cone breakup show up by way of non-linear distortion before, even when that driver's breakup @ 10khz was well down, being crossed at 2.7khz LR4 (with a typical 2nd order electric filter). So I think one should really try to manage these resonances with best practices whenever you can. And the small bypass cap is cheap and easy to do.
As I've always been told and read;
Parts in parallel and then placed in series with driver = parallel notch.
Parts in series and then placed in parallel with driver = series notch.
Parallel LC (tiny tank cap), makes an infinitely peaked parallel notch.
Series LC makes a bottomless trap, or a pit with no bottom, shorting of a frequency region.
Parts in parallel and then placed in series with driver = parallel notch.
Parts in series and then placed in parallel with driver = series notch.
Parallel LC (tiny tank cap), makes an infinitely peaked parallel notch.
Series LC makes a bottomless trap, or a pit with no bottom, shorting of a frequency region.
I would not have a clue how to convert the values here for the 4ohm version. Is there a math solution based on the resistance difference? really hate my ignorance, I am trying to work on that but it is a slow slog as you can imagine anyway it is very helpful to read the post and see the examples of how others have worked on these issues, Your observation that the driver does work NICELY gives me intensive to continue looking for answers.
You May be encouraged to try the driver base on at least some Positive comments
"Once tamed, the L series cones have some of the smoothest responses out there, and, a great sound too." Post 43 Really would like some collective wisdom here ( many tackling the challenges together ) A collective answer may be Interesting and rewarding why not get on board for the ride ?
If I get time later today, I'll trace and load the 4 ohm driver ZMA and see what it does to the frequency response.
The good thing about Seas drivers, is their production consistency. A bottomless series notch (the leg that has the 7.47uF and 0.05mH) needs to be precise - meaning if you have drivers made from a company that has variable consistency - you must measure each driver to precisely hit the breakup.
Therefore a notch designed for one system should work well in another using Seas.
Hmm, being a 'believer' in the audio pioneer's design mentality, using/recommending the 'acoustic solutions to acoustic problems' ethos in this case, i.e. would find the 'problem' if I didn't know from experience and deal with it physically as I started to explain in my post #2, instead just answered the Q as presented since the audio design collective's dictum is one of just 'hammering it down' with a bunch of costly components with its associated insertion losses, etc., though arguably the best solution where time is the dominant constraint, so YMMV, etc..
The passive parts I listed are hardly costly. Very small value inductors and capacitors. In my system the inductor is 20awg and some cheapie mylar caps from memory.
If you know where the breakup is being induced - physically manipulating the driver might be an option, but one has to wonder why Seas didnt' do that in the first place if they knew the solution?
Trial and error physically attaching bits and bobs may trade breakup reduction for other anomalies in the passband. Still, no harm as long as one's trial and error is reversible.
Thanks!
Right, doping and/or some form of 'critical damping' depending on the needs of the app, so spot on for one solution and my first 'go to' since it's so easy to include it in/on the driver(s) protective grill/screen, a 'must have' in my active DIY audio 'career' to cope with various 'critters', pets, liquid/food 'spills', etc., not to mention any sporting event's more overt 'enthusiasms'.
😉
When used in a three way, the L18 can take LR2 quite easily without issue.
Here we have a parallel LC of 0.05mH and 10μF.
Here we have a parallel LC of 0.05mH and 10μF.
I think you mean series LC. To use those values and kill the breakup places it in a shunt position.
M one comment so far does that, works to sort the problem att teh source and not use a band-aid such as a filter.
These MCM Al cone really benefitted from that coat of ModPodge. i don’t use it on the Al alloy FRs a play with, those get a coat ofthinned acriylic gloss. Actually 2 coats.
https://www.t-linespeakers.org/FALL/toobz/index.html
https://www.t-linespeakers.org/drivers/MCM55-1855.html
dave
Thank you for you HELP I am looking forward to the Work, It is work so thank you
Aluminium cones don't seem to be well damped... so, taking paper off the table as a solution makes aluminium an esoteric solution.
It's interesting because paper cones are common with waveguided tweeters, and they need to be crossed right on the cusp of breakup. So, if paper can be used into breakup then what is aluminium providing?
Basically, piston behaviour through the pass and transition band. Seas et al aren't cost saving: they put a lot of time & effort into concentrating bell modes to relatively high Q products at relatively high frequencies, the ideal from that design perspective being a single large initial 'let go' point, with any subsequent peaks being of lesser amplitude. Ideally, units of this type are functioning in purely oscillatory action in a complete design with no surround resonances and no use of TL modes to extend the upper BW, neither of which are technically as precise from the POV of linear & non-linear distortion, although all the usual caveats come into play there, so YMMV as always. 😉 Oddly enough, as far as Seas go, in their 7in category the cheaper L18 arguably has a superior cone design to the cast magnesium Excel, although its motor isn't as good. Name your poison on that front...