Could someone model these drivers for me?

I already have built this speaker using the plans on the site and they sound great. The problem is there is no bass at all. The t/s was not orig on the site because the designer wanted an outside company from the driver builders to test them. The web site is

http://www.parkeraudio.net/prod03.htm

If you also have the time could you model these driver for the enclosure designs on the site already and see if it is a good match?
 
Given the numbers on that web page. my modeler comes up with something quite strange.

dave
 

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I don't think he was givin correct t/s when he had the drivers made. He recently had them tested by a third party and these are the specs he got back. They have a great midrange but the speakers have little to no bass and sound pretty thin. I am sure there is a more suitable enclosure then the one he designed but I don't have the s/w to design one. Personaly I was thinking about a TL or a back loaded horn but I don't have the tools to see if they would work.
 
I'm not sure that modelling is incorrect; the huge hump in output at ~64hz could be intentional. That way, when you play the live version of "Hotel California," the listener hears that big *THUMP* and feels it in his chest, and says, "wow that's a lot of bass! These speakers are very good!"

What he doesn't realize is that it may be a lot of bass, but it's not actually very good bass.
 
Dave,

I think you converted the .78 Vas to cuft as if it started as liters, but I'm pretty sure it must be cuft. I tried Martin's TQWP worksheet and got what seem to be pretty good results. I do have a question about the inputs. Since this is 2 drivers, is the Vas doubled or cut in half ? I only got good results doubling Vas, so I hope it is correct. The only input changes I made were for Re, Sd, and Vas to account for there being 2 drivers. Do any other T/S parameters change with dual drivers? I came up with a 60" pipe, 56cm top (25% of Sd), 904cm bottom (4xSd), drivers centered at 50% and a 4"dia 8" port. I was trying to get a pipe that looked pretty good with the Parkers and an FE206E, so I can use a changeable baffle.

Also, I couldn't find any examples of folding a TQWP with an MTM set of drivers. I'm guessing that the tweeter will need to go on top, but I'm unsure of that effect since this is a crossoverless MTM design. Can it be folded and achieve the same result as a straight pipe using 2 drivers? It would be nice to avoid a 60" tall speaker.

I bought these things to get high efficiency and low impedance for my Decware amp, but the recommended BR models silly with no bass below 90hz or so. Any suggestions for alignment would be greatly appreciated. Right now I'm leaning toward a TQWP due to the simplicity in build, GM mentioned that 2 drivers is beneficial, and a number of people like their 206's in a pipe, so with the higher Qts and slightly higher Sd, I think these will be even better.
 
Greets!

Right, Vas, Sd doubles, Re, Le halves for parallel wired. BL changes only a tiny fraction so can be ignored. T/S max flat assuming Vas is in ft^3 and ~no series R: ~10.366L, ~111Hz F3, ~92Hz Fb.

I didn't see any dims for the cab other than a too large ~35L net Vb/61Hz Fb, so can't comment on the FR beyond that if driven with an SS amp they are only capable of 'one note' bass centered around ~61Hz.

I assume though that the Zen has significant output impedance so the effective Qts will rise, 'filling' the cab up to some extent, but may not be enough so some series R may still be required to flatten it enough if the XO and cab width doesn't account for any/enough BSC. At a glance it looks like Qts = 0.376 is required.

Anyway, once dialed in, my SWAG is that based on the limited driver specs then a much more 'solid' 40Hz alignment than this one can be had from this kit, though the XO may need to be tweaked.

GM
 
johninCR said:
I think you converted the .78 Vas to cuft

The program does the conversion when i switch between metric & english units... it also automatically takes care of 2 drivers

Also, I couldn't find any examples of folding a TQWP with an MTM set of drivers. I'm guessing that the tweeter will need to go on top, but I'm unsure of that effect since this is a crossoverless MTM design. Can it be folded and achieve the same result as a straight pipe using 2 drivers? It would be nice to avoid a 60" tall speaker.

An MTM would need to be at least as tall as the top driver, meaning you couldn't fold it in half (assumming an ML-TQWT driver placement at half... for a push-pull bipole that 50% is quite convienient, meaning you can place the drivers at the top of the folded in half box (note: the white space at the top of the picture defines the extents of a straight version of the pipe)

[IMGDEAD]http://p10hifi.net/tlinespeakers/TLS/FALL/bipolar/images/folded-tn.gif[/IMGDEAD]

details & bigger pictures -> http://www.t-linespeakers.org/FALL/bipolar/index.html

dave
 
Greets!

According to this it's only 0.8 ohms http://www.decware.com/zpage3.htm, but it's stable into 2 ohms so with two of these nominal 6 ohm drivers in parallel we're looking at a significant Qts increase. Anyway, just crunching some numbers I get an effective 0.337 Qts so it appears the designer did his 'homework' if all our assumptions are correct.

Unfortunately this is counter to DJNUBZ's experience so without more specific info there's not any point speculating further.

WRT measuring the output impedance, if the DF is known then amp resistance = (R Load/DF), where R Load is the tap rating. Otherwise, put in a sine wave at the frequency of interest (low level as to not burn resistance) and measure the AC volts with the outputs open. Don't leave the amp on very long with no load or damage to the amp may occur, or potentially to you if a tube grenades. Find the resistance across the outputs that reduces output by half, this is its output impedance (Zo).

For DF @ 'x' ohm: DF = 'x'/Zo

GM
 
GM said:
Greets!

Yeah, at 4 ohms the pair is a nominal 8 ohms with Qts up to ~0.612, and the calc'd efficiency is still ~93dB/W/m so it really opens up alignment possiblities.

GM

GM,
I use the Select model amp and I'm trying to maximise the performance of the little 2 watt amp than is 4-5 watts into a 2ohm load (which BTW it likes and is supposed to be stable almost to a dead short), so I'll still be limited on alignments. You and Dave lost me with all the electrical stuff (I stick to speakers). Listening to the set on OB, I can hear the higher Qts compared to my FE206, so I think they will perform better than the 206 in one of the resonant enclosures. Is my gut feel on the right track or am I missing whole boat load of things I don't understand?
 
Greets!

The alignments are what they are based on the driver's specs and how much the amp's output impedance impacts it so the > this value is, the > the available alignments.

WRT transient peak capability, this is a function of the amp's power supply (dynamic headroom), so if it's only good for 4-5W then with low 90s eff. speakers it will clip with regularity on dynamic source material unless you sit fairly close. With tubes, this creates a laid back ('soft') presentation that many folks prefer so it may not be a big deal to you.

If SS driven, then you'll need enough power to offset the efficiency loss since when they clip, it's anything but euphonic.

WRT your 'gut feel', if the amp has 4 ohms of output impedance on the 2 ohm tap, or at least has somewhat more than the published 0.8 ohms and you add a series resistor to make up the difference, then OB mounting isn't out of the question, what with an effective ~0.612 Qts if two drivers wired in parallel are used. Otherwise, a resonant cab will be required to offset the fairly low effective Qts.

GM
 
GM said:
Greets!

Yeah, at 4 ohms the pair is a nominal 8 ohms with Qts up to ~0.612, and the calc'd efficiency is still ~93dB/W/m so it really opens up alignment possiblities.

GM


Are you saying that two 93db/w/m speakers run in series is still 93db/w/m and not 96db/w/m? Could you explain this? I thought that for each doubling of drivers you get a 3db increese and that weither they were in series or parrallel didn't matter.

Did we decide if that first graph was modeled correctly on the vas?