When in doubt, compare to other sim programs. RM does have a function of applying all sorts of FR manipulation but this affects the main curve also, and sloping in FRD does only extend the curve in a desired direction. Regarding slopes I used, I think the LF was 18db/oct and HF -33dB/oct, but you will decide once you have it visually there in FRD. Tweeter and midranges in phase, woofers out of phase.
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Lojzek
Right. PCD doesn't allow you to invert the woofer, requiring inverted mid and tweet in the program. But yes, in real world, invert woofer and you're done. When I get the time, I am going to dig into FRD. Thank you
FWIW (and you are probably already aware) I got to the bottom of the PCD Z offset misinformation debacle. Bagby changed the required setting from positive to negative between versions 6 and 7, to align with convention of other modeling software, but never changed the instructions. In any statements made on line - if before version 7 he said positive - if after, negative. So I was getting mixed information. Thanks for helping me understand the correct way.
Right. PCD doesn't allow you to invert the woofer, requiring inverted mid and tweet in the program. But yes, in real world, invert woofer and you're done. When I get the time, I am going to dig into FRD. Thank you
FWIW (and you are probably already aware) I got to the bottom of the PCD Z offset misinformation debacle. Bagby changed the required setting from positive to negative between versions 6 and 7, to align with convention of other modeling software, but never changed the instructions. In any statements made on line - if before version 7 he said positive - if after, negative. So I was getting mixed information. Thanks for helping me understand the correct way.
He only changed it to negative to reflect that of other programs and eliminate confusion comparatively. When in fact, the (-) itself doesn't make sense as Z is further away from the listener and a larger number the further toward the front wall it goes.
Convention triumphed over reality this time, reflecting Z in relation to the loudspeaker baffle, and not the listener.
But yes, this info is correct relating to PCD release; PCD6 (and earlier) Z = +; PCD7 (and later) Z= -.
Still a powerful program, albeit slightly restrictive in circuit layout.
I use it a lot still to model xovers.
Wolf
Convention triumphed over reality this time, reflecting Z in relation to the loudspeaker baffle, and not the listener.
But yes, this info is correct relating to PCD release; PCD6 (and earlier) Z = +; PCD7 (and later) Z= -.
Still a powerful program, albeit slightly restrictive in circuit layout.
I use it a lot still to model xovers.
Wolf
Steve,
how much did you enter for Re of one woofer (coils in parallel) when simulating vented enclosure? According to datasheet Re=4, yet it says Zmin=3.2 at 159Hz. Normally Re is lower than that.
how much did you enter for Re of one woofer (coils in parallel) when simulating vented enclosure? According to datasheet Re=4, yet it says Zmin=3.2 at 159Hz. Normally Re is lower than that.
Lojzek,
I used Re=4, but have always been suspicious of the number. I've attached another data sheet where the TS parameters are based on an individual coil at 8 ohms, and says 2 at 8. Since consistent with the 4 with 2 in parallel, I went with it. The driver has been out of production for maybe 20 years. I bought them as NOS 8 or 10 years ago after blowing out the original DVC 8/8 drivers (another brand). It was a well regarded driver back then, and cheap, but very little information available. I have considered replacing them as well, but this rebuild has gotten a bit pricy.
On another note, I've stared looking into FRD Response Blender. Instructions seem to indicate the input FRDs should be a combination of near field and far field measured response data. Of course, I can't measure anything, and don't have the mid range drivers yet anyway. Am I just inputting the raw driver FRDs?
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Re=4 is very likely a typo. Peerless was always a well respected brand name, and their practice of producing nominally 8 ohm units had Re in the 6R range.
Even though FRD Response Blender was designed to merge near and far field measured data, you can use it as a phase extractor without any other concerns. Prepare the files in RM and then extract phase with FRD.
Even though FRD Response Blender was designed to merge near and far field measured data, you can use it as a phase extractor without any other concerns. Prepare the files in RM and then extract phase with FRD.
Not sure about the typo, but I agree it doesn't look right. I would have expected something in the 3.1 range. Could roll the dice, and just go that way, based on that min Z and the rest of the IMP curve. Spent many hours looking for more information on that driver, hoping to find somebody that had actual measurements. But this is a "vintage" driver, and nobody was doing that back then, and internet was still young. I'm more concerned about the correctness of the crossover than the box. I can't do much about the existing box, other than reducing the volume (wrong direction) or messing with the port lengths.
I figured as much on importing the files into FRD from RM, but wanted to confirm. As you can tell, I only know enough to be a dangerous nuisance. Your help is much appreciated.
I figured as much on importing the files into FRD from RM, but wanted to confirm. As you can tell, I only know enough to be a dangerous nuisance. Your help is much appreciated.
Crossover will be correct as much as input data is, and by default this isn't optimal, but the rusults could be satisfying. We will know that once you report the findings, if you choose to do so. Beacuse of the uncertainty of the outcome, it would make sense to avoid expensive x/o parts. These midrange units are "difficult" to design a simple LP filter for, though inevitable for its properties dictate so.
Thanks, Lojzek (and AllanB).
Yes. This was understood from the beginning. I've just been trying to avoid the "big miss", which is why I came to this forum when I got stuck. Thanks to you guys, I've learned more about reading phase traces (rather than just checking reverse nulls), more about minimum phase, and the Z offset thing would have been a huge miss, now averted. Forever grateful.
As you were going through this exercise, was there another mid range driver that came to mind, that you thought might be more appropriate? I have modeled several, and intend to go back through them now with the Z offset corrected. Hard to find a reasonably priced true mid range out there - they all seem to be mid-bass drivers these days, with cone breakup and/or off axis dispersion issues above a 2k cross with a simple low slope. Maybe I'm being too conservative on that (?). I gravitated toward the SB15NBAC because of its high breakup point and relatively high dispersion point (based on factory specs/curves, of course, and some independent test results out there that seem to corroborate). But I have no particular allegiance to it otherwise.
Regarding the Peerless Re: I don't know why it didn't dawn on me until yesterday, but that is one spec I can check with a simple multimeter. I'm going to pull one or two of them and do that.
Thanks, again
Yes. This was understood from the beginning. I've just been trying to avoid the "big miss", which is why I came to this forum when I got stuck. Thanks to you guys, I've learned more about reading phase traces (rather than just checking reverse nulls), more about minimum phase, and the Z offset thing would have been a huge miss, now averted. Forever grateful.
As you were going through this exercise, was there another mid range driver that came to mind, that you thought might be more appropriate? I have modeled several, and intend to go back through them now with the Z offset corrected. Hard to find a reasonably priced true mid range out there - they all seem to be mid-bass drivers these days, with cone breakup and/or off axis dispersion issues above a 2k cross with a simple low slope. Maybe I'm being too conservative on that (?). I gravitated toward the SB15NBAC because of its high breakup point and relatively high dispersion point (based on factory specs/curves, of course, and some independent test results out there that seem to corroborate). But I have no particular allegiance to it otherwise.
Regarding the Peerless Re: I don't know why it didn't dawn on me until yesterday, but that is one spec I can check with a simple multimeter. I'm going to pull one or two of them and do that.
Thanks, again
If it were me, I'd definitely stick to Peerless PPB cone midwoofers, either 4" or 5.25" units. These are now still available at PE for a great price. Their truncated frames can come in handy with mtm's to further reduce ctc distance.
I am glad you rembered having a multimeter. Perhaps you could go a little further and use a sound card of some sort, just about any half decent would do for impedance measurements under REW.
I am glad you rembered having a multimeter. Perhaps you could go a little further and use a sound card of some sort, just about any half decent would do for impedance measurements under REW.
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Thanks. I'll model them, and see how they fit. Since 8ohm should I wire in parallel for nominal 4ohm paired?
FYI, Peerless woofer DCR measured 5.0 ohm single coil, and 2.5 ohm both coils in parallel.
Lojzek,
I checked into this driver and found two different data sheets out there. Parts Express has one, which matches the older Peerless data sheet. Tymphany has another, which does not match the other on a number of criteria, including the FR and IMP curves themselves. The driver is in the Tymphany HDS line now. Do you know which is correct? I'm guessing there might have been a driver update at one time (?).
To be clear I’m referring the the 830860, 5 1/4”. I’m mobile and don’t have them in front of me. If you look at the data sheet in the PE website and compare to the one on the Tymphany website you’ll see the differences. The Fs and impedance curve in general is quite different.
Lozjek,
Interesting that the Peerless P830860 seems to play nice with the other drivers in either paired in series or parallel configuration, without a lot of component changes. Even system impedance is good either way: Peak at 12 ohms (middle of driver) in series. Peak at 10 ohms (tweeter side) in parallel. And nothing below 5 ohms in either case. Does this seem right? I guess I was expecting more variance.
Are you familiar enough with this driver to know how accurate the Peerless spec sheet and curves are? (Sounds like you've used or at least modeled it before).
Interesting that the Peerless P830860 seems to play nice with the other drivers in either paired in series or parallel configuration, without a lot of component changes. Even system impedance is good either way: Peak at 12 ohms (middle of driver) in series. Peak at 10 ohms (tweeter side) in parallel. And nothing below 5 ohms in either case. Does this seem right? I guess I was expecting more variance.
Are you familiar enough with this driver to know how accurate the Peerless spec sheet and curves are? (Sounds like you've used or at least modeled it before).