GM said:
I did put an equation into the worksheet to re-calculate Qts, but I got a different number, so I'll check my formula.
[Added a few minutes later] Actually, I just copied the formula from a worksheet on Martin's web page. The worksheet is for the Fostex fe206e. (Of course I changed the original Q to the one for the fe107e.)
Here is the formula:
Qed' := Qed*(Re)*(Re-Rs)**-1
Is that right?
I'm probably already reaching the limit of what those little drivers can do, even in a small room. For a given SPL, cone excursion quadruples every octave, right? And the xmax on those is tiny. Still, I'll play around some more.
Dave
"Nothing vented nothing gained."
>For a given SPL, cone excursion quadruples every octave, right?
====
Correct.
====
>And the xmax on those is tiny. Still, I'll play around some more.
====
Yeah, and I don't know how much excursion it has before either popping out of the gap and hanging, or bottoming out. For sure I wouldn't drive it past 1/8" until you find out what Xsus/Xmech is.
====
>I think I have the Qes figured right now, and I put in the numbers exactly as you said. Here's the function, assuming a total added resistance of 5 Ohms:
====
Hmm, don't know what you're doing, but you're not getting the right response. Notice that the IB response hasn't flattened out so it's not plotting the higher Qts response, ergo the higher Q vented response.
GM
====
Correct.
====
>And the xmax on those is tiny. Still, I'll play around some more.
====
Yeah, and I don't know how much excursion it has before either popping out of the gap and hanging, or bottoming out. For sure I wouldn't drive it past 1/8" until you find out what Xsus/Xmech is.
====
>I think I have the Qes figured right now, and I put in the numbers exactly as you said. Here's the function, assuming a total added resistance of 5 Ohms:
====
Hmm, don't know what you're doing, but you're not getting the right response. Notice that the IB response hasn't flattened out so it's not plotting the higher Qts response, ergo the higher Q vented response.
GM
GM said:
It actually is flattened out a little bit, but very little. I'm probably not calculating the new Qes correctly. See the attachment.
Yep, now it looks like mine. I have the same problem with Mathcad too, but I just assumed it was my machine since it's so outdated 'n slow.
GM
GM
GM said:
I tried it both ways. I liked it better across only the 4 Ohm. ... a little less treble boost than BSC boost. There's not a big difference of course.
Fair enough. Not having heard this driver, I was just curious. Yeah, they impress me too. I've been designing tower speakers (now ML-TL) since the late '60s, but no formula I could ever find would accurately predict vent length, and not having the math skills to wade through all the gas law formulas I never could come up with any calc or even rule-of-thumb to figure it. And of course stuffing was trial n' error.
GM
GM
Ahhhhhhhhhh!!!!!!!! Blaspheme! MathCad is a big part of my pathetic life!
I have never had the problem you describe. Sometimes if the screen gets confused, try hitting "control-R" to refresh.
Rather than doing a stretch Locust 34 inches tall, it would make more sense to do an even taller floor-standing speaker using the fe127e. That one has a lower Fs, higher Qts, and bigger xmax.
GM, would you care to try your magic on that one?
I'll give you something to shoot at:
GM, would you care to try your magic on that one?
I'll give you something to shoot at:
At a glance, I doubt I can improve on it without going large flared. I did an extended max flat alignment awhile back for someone that a false bottom filled with kitty litter/whatever can be added to get the driver up high enough, but AFAIK it wasn't built:
L = 39.46"
SO/SL = 43.785in^2
driver down 14"
1.875" dia x 0.5" long vent near/at the bottom
BTW, does the view/refresh or ctl-r work for you?
GM
L = 39.46"
SO/SL = 43.785in^2
driver down 14"
1.875" dia x 0.5" long vent near/at the bottom
BTW, does the view/refresh or ctl-r work for you?
GM
The phase plugs arrived and I installed them. I did one side first and listened A/B. The plugs made a very distinct improvement. Not only was the treble distortion almost completely gone, but even the bass seemed to be better defined. I did the other side, then listened to them a long time last night. I think these little things may be sounding about as good as the Ariels now.
Sorry for that OT-question that just comes to my mind.
GM, I "re-simulated" a lot of designs you´ve given (thanks a heap)
to hopefully learn something from them.
It´s going well so far but what still puzzles me is the driver position.
You always seem to have the ratio around 0.35xx.
I know (at least I think I know) that one should damp out resonances like the 3rd harmonic.
But especially there where you seem to set the driver the overall resonances seem higher to me.
I always get good results at around 0.45 +-0.02.
In the recent FE-127E design for example at 0.45.
Isn´t it advantageous to get a TL with overall minimized resonances
or am I completely on the wrong path?
Best regards
Jens
BTW: THIS one is on the way (the 42"). If it´s not gonna work out I´ll come over.😉
GM, I "re-simulated" a lot of designs you´ve given (thanks a heap)
to hopefully learn something from them.
It´s going well so far but what still puzzles me is the driver position.
You always seem to have the ratio around 0.35xx.
I know (at least I think I know) that one should damp out resonances like the 3rd harmonic.
But especially there where you seem to set the driver the overall resonances seem higher to me.
I always get good results at around 0.45 +-0.02.
In the recent FE-127E design for example at 0.45.
Isn´t it advantageous to get a TL with overall minimized resonances
or am I completely on the wrong path?
Best regards
Jens
BTW: THIS one is on the way (the 42"). If it´s not gonna work out I´ll come over.😉
- Status
- Not open for further replies.