Hi Ian,

thank you for your reply.

I am cutting out some of your responses that I have a question on or I do not understand at all, so the back-and-forth does not turn into a mess. The forum software is not the best on such a manner of conversation.

Re. 1

IM: "Yes. You can however manipulate the QES + some series resistance Rs like adding a series 0.2 -.033 ohm resistor and a parallel shunt resister like 80 ohms down to 39 ohms on the woofer."

I am actually aware of the series resistor technique, I used it in shaping the slope of the response. But I am not sure what the parallel shunt resistor is supposed to do. I will ascertain whether the software I use - Unibox - will let me add a parallel resistor.

IM: "You also need to consider how your going to cover the first two octaves. The sealed 515 system will yield a damped mid bass but it has a relatively limited Xmax. Without the support of a bass reflex port or vent the 515 will have subjective limitations on its dynamic output below 100 hertz."

It is my understanding that the room characteristics can help with the lower octaves. And, yes, the limited Xmax will prevent using Linkwitz transform.

In this regard, I have difficulty to understand the concept of the claimed "subjective limitations on its dynamic output below 100 hertz" (not only by yourself). Here is my, perhaps incorrect reasoning. Since I am fortunate to live in a quite environment, my listening level is on overage 75 - 80 dB. A well recorder (classical) music has about 15 dB dynamic range, so the peaks will be 90 - 95 db. In my experience, apart from some organ works, 1815, Also sprach Zarathustra, and the like, there is not much content under 30 - 35 Hz. if the model is realistic, there is about 3 dB reserve. What am I missing?

When I had Bruce Edgar's Titan folded mid-horn that, in my room, did not produce much below 35 Hz, I did not seem to have missed much. Perhaps I am not a golden ear unlike other audiophiles.

I can always build a near-field subwoofer.

Re: 2.

IM: "A driver volume will not have a perceived effect in a 120 L enclosure."

I estimated the driver volume and bracing at about 10 l, so perhaps I should have attached a 110 l enclosure (no fill considered). But there is about 1 dB difference, so in a big picture, you are correct.

IM: "In your situation l think it’s best to try and validate your woofers TL parameters within a model (l can do that for you)."

I would like to learn, how to do that myself, you are already wasting enough time on me. In fat, we had already moved away from the original question, which is fine with me, but I hate to abuse your generosity.

I am rather lucky, because my T/S are withing about 5% of the published data.

Re. 3

IM: "My recommendation is to acquire the Dayton DATS3 woofer tester or attempt TL measurements with REW and an audio interface. See the REW help guides online."

O.K., I will re-measure with the REW.

IM: "In the scheme of things the group or class in which your 515 belongs on the Qts continuum is more important overall. In other words be mindful of what it’s intended purpose is."

I know, all my previous inquiries met with a response that it will not work the 515B was meant to be a horn driver. Maybe I should just forget it, sell the Altec and concentrate on the TAD. Or, reacquire the Titans.

Kindest regards,

M