That is a shocker for a manufacturer to be so far out with the truth. Same with Tangband response graphs.
btw I really think Zaph's site is the dog's..its good to read so many impartial tests -big fan of Zaph, pls review the new Jordans for us
At the price they cost don't ask for suspensions from Kurtmuller...Each batch will have specs of its own, the important thing being the consistence of the production of each batch ... But they cannot make a new part number and datasheet for each batch ... for a bloody 20$ thing... And btw, you might have some kund of tester too...
Not entirely impartial. He has his own range of drive units (which incidentally from their data sheet are on an Fs tolerance of +/-10Hz)
See above. Not necessarily so surprising. Depends on how they are measured -voltage, whether the suspension was broken in or not, production tolerances & so on & so forth. You want bad, I know of a certain 12in wideband drive unit that was supposed to have a quality factor of ~0.5. The purchaser measured his pair at over 1.0 Even making allowance for these factors, that's ludicrous.
See above. Not necessarily so surprising. Depends on how they are measured -voltage, whether the suspension was broken in or not, production tolerances & so on & so forth. You want bad, I know of a certain 12in wideband drive unit that was supposed to have a quality factor of ~0.5. The purchaser measured his pair at over 1.0 Even making allowance for these factors, that's ludicrous.
Last edited:
Ok GDO, I'm going read that article you linked. Thank you.
So you're saying that when the driver is driven harder the parameters will change. That makes sense, the drivers are dynamic. However, how much is acceptable. Is a 25hz difference in Fs considered within the dynamic shift of the driver? This is all new to me so I'm not theorizing here, real questions.
Bill poster,
I also enjoy Zaph's site. I'm of the objective > subjective mindset, at least until I've matured in my ability to examine audio equipment. At 28 I've only been serious about this stuff for several years. His site has pushed me a lot to get equipment and really understand why something doesn't sound good, or does. I've comparitively measured 3 drivers from his tests and all have lined up perfectly with his results for both impedance and Frequency Response. The manufacture's... so so.
As for the Jordan's, bad data or not, it's good to see the FR industry continue to push product development. I doubt I'll ever own Jordan's given the price, but it's nice to see new products regardless.
So you're saying that when the driver is driven harder the parameters will change. That makes sense, the drivers are dynamic. However, how much is acceptable. Is a 25hz difference in Fs considered within the dynamic shift of the driver? This is all new to me so I'm not theorizing here, real questions.
Bill poster,
I also enjoy Zaph's site. I'm of the objective > subjective mindset, at least until I've matured in my ability to examine audio equipment. At 28 I've only been serious about this stuff for several years. His site has pushed me a lot to get equipment and really understand why something doesn't sound good, or does. I've comparitively measured 3 drivers from his tests and all have lined up perfectly with his results for both impedance and Frequency Response. The manufacture's... so so.
As for the Jordan's, bad data or not, it's good to see the FR industry continue to push product development. I doubt I'll ever own Jordan's given the price, but it's nice to see new products regardless.
The blunt fact is that T/S parameters, mathematical constructs though they basically are, work. Within certain limits. They are not perfect, as has been noted, so ideally, you want to be designing with some allowance built in.
A 25Hz shift in Fo is not typically simply due to a shift in drive level. About 5Hz might be expected. But you need to consider the points I mentioned too regarding whether the suspension is broken in, what the production tolerances etc. are like &c.
What the Fountek is exhibiting in terms of manufacturer published figure and 3rd party measurement is not especially uncommon. As mentioned, according to its data sheet Zaph's own ZA14W8 Midbass has an Fo of 65Hz +/-10Hz, which isn't all that far removed from what you've noted re the Fountek units, if you took samples from either extreme (which can happen unless the units are matched).
A 25Hz shift in Fo is not typically simply due to a shift in drive level. About 5Hz might be expected. But you need to consider the points I mentioned too regarding whether the suspension is broken in, what the production tolerances etc. are like &c.
What the Fountek is exhibiting in terms of manufacturer published figure and 3rd party measurement is not especially uncommon. As mentioned, according to its data sheet Zaph's own ZA14W8 Midbass has an Fo of 65Hz +/-10Hz, which isn't all that far removed from what you've noted re the Fountek units, if you took samples from either extreme (which can happen unless the units are matched).
Last edited:
No.
Fs = f(V, weather, orientation)
Look at the difference in the FE127eN data. Both mine & Mark's numbers are correct.
Typical computer drive is mV, industry standard LMS (or one other?) are more typically a solid volt. There is also the issue of whether the computer can source sufficient voltage to drive the current source measuring scheme most of us use.
dave
... or simply " drive level dependant"... Do you mean that the liters i need for my cabs are also "drive level dependant"?
Fortunately the parameters change such that tuning of a sealed box is not impacted much (particularily if system Q <0.7), but that tightly tuned BR will be in & out of tune with volume control levels & with the dynamics of the music.
dave
Agree, that 's why i said, instead of speculating with silly simulations, build a plausible cheap quick and dirty cabinet for that driver and pour some music in it to make a realistic idea of how it behaves in real life conditions ... and better, build a few different ones...
So what do we need simulations for ? Yes, it's a good question: what the hell do we need simulations for ?
Last edited:
He has his own predudices which add colour to what is there. Still very useful.
dave
Are these the only factors?
I imagine weather would have little to do with it. Temperature in room is fairly consistent among places around the world. Humidity varies. Pressure varies slightly.
Orientation makes sense. I suppose a DIYer could measure upright, on it's side and facing down, then see if there is much change.
Like orientation, a DIYer could measure at varying voltages to determine the max/min Fs.
Thanks.
Simulations are not silly. Far from it. Remarks like that are silly. Software can be an extremely effective tool, but like anything else, its utility depends on how well it is used. As I often say, knowing what software does is important, but knowning what it doesn't do is equally so.
Don't agree. Simulation can be as silly or wise as the guy at the simulator might be... I'm afraid that the level of deep understanding you are talking about is not so widespread among hobbysts ... and logically so... but i find somewhat ridiculous observing how people merely put "faith" in things they simply don't understand...
Probably not the only factors.
The big one with weather is pressure. I have seen 5% or more variance just from the weather. One of the reason i always test all the drivers i am matching in the same session.
dave
The variation of Fs with weather and drive level is very weak compared to its direct dependance on mechanical compliance. This means that breaking in the suspension definitely changes the Fs. Changes in weather are much less important.
While testing, you certainly don't want to exceed the driver's X-max. And, ideally, the measurement must happen under small signal conditions because the T/S parameters are exactly that, small signal parameters. A volt through the driver is still fairly high and may lead to erroneous predictions.
Also, anybody who is measuring the drivers facing up must know something called gravity. You can't expect to get the same result facing up as you would with the driver vertical. These are all basic things and I'm assuming people such as Zaph and diyers who invest in measurement systems must know.
Testing Loudspeakers by D'Appolito is a superb resource.
While testing, you certainly don't want to exceed the driver's X-max. And, ideally, the measurement must happen under small signal conditions because the T/S parameters are exactly that, small signal parameters. A volt through the driver is still fairly high and may lead to erroneous predictions.
Also, anybody who is measuring the drivers facing up must know something called gravity. You can't expect to get the same result facing up as you would with the driver vertical. These are all basic things and I'm assuming people such as Zaph and diyers who invest in measurement systems must know.
Testing Loudspeakers by D'Appolito is a superb resource.
Don't agree. Simulation can be as silly or wise as the guy at the simulator might be... I'm afraid that the level of deep understanding you are talking about is not so widespread among hobbysts ... and logically so... but i find somewhat ridiculous observing how people merely put "faith" in things they simply don't understand...
I certainly agree that blindly following the numbers is never a good plan. You can hardly blame software if people don't learn how to use it properly and get poor results though. That's simply a case of a duff workman blaming his tools. Blanket statements that simulations are 'silly' with no qualifications at all are not likely to result in this thread moving forward in a positive fashion. As stated, software can be an extremely effective tool. It is simply a matter of learning how best to use it.
Last edited:
I think he sells a Zaph design through Madisound, is that what you mean? So you think he's biased in his reviews because of this?
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.