Quote:
SteveCallas wrote:
 The RLp15 LLT design doesn't suffer from this because I accounted for it in the design. 260 effective liters with a ~15hz tune minimizes the discrepancy in the tie in of port output to driver rolloff enough that it isn't a significant issue. |
Right, it isn't a significant issue...thats exactly right. If the issue can be resolved with proper volume and tuning frequency, then its totally possible to take the same precautions with another driver that may also suffer from the effects of high Bl and low Qts in this alignment obviously. But keep in mind, we were talking about the driver itself and how it effects the entire allignment...not one of your designs.
Quote:
SteveCallas wrote:
That's because an it's an in room measurement  room gain and/or reflections easily mask any small FR changes. |
That pretty much goes without saying...and I never said in-room measurements should or normally do look like simulations. This was said only in reference to a comment you made about port output and driver rolloff... at this point its a non-issue even with drivers with high bl and low Qts because we account for them in the design phases, except for those extreme situations...like a Tc-5200 for example.
Quote:
SteveCallas wrote:
To match the simulations, you'd want to do a ground plane measurement.....since that's not very easy, close mic measurements of the drivers and port with no crossovers in play is the next best option. Ryan happend to do something close to that, except he left the 100hz crossover in play. 
You take out the crossover and the upper frequency bass will be even higher in magnitude. In the case of Ryan's specific design, max output should be somewhere in the neighborhood of 110hz. You combine the close mic driver response with the port output and you have a response that looks VERY similar to the simulation. All said and done, the simulations are very accurate. A ported sub response is no more difficult or no less accurate to predict than a sealed sub with an EQ boost (the EQ boost is replaced by port output). |
The above also goes without saying, and is certainly good information for people to know
Quote:
SteveCallas wrote:
Aside from the issues a resurgence in port output will create if left unattended to, the bigger problem is that such drivers that are prone to that want smaller enclosures to get away with lower tunes. This goes against being able to create an affective LLT, and this is why the RLp15 is ALMOST not a good choice. Much smaller than 260 effective liters and you'd fall into port troubles as well as reduce low end efficiency to the point that in room response probably wouldn't be as flat as it is. |
Whether or not the Rl-p 15 is or isn't a good choice for an LLT alignment was never questioned..............not by me or anyone else in this thread IIRC. There are many other great things about the driver that make it suitable for this use but having a relatively high bl and low qts isn't its strong point for reasons already discussed here.
Will, **** thats huge :raped: