Do it all 15" driver

[agedhorse]

I assume you know what this is.

The hardware it connects to let's me view ir's, phase, frequency, and several other things like a host of electrical signals IN REAL TIME.
I tune stuff for fun

Ooooh, it's a consultant's wanker tree...

 

[B-string]

Sincerely asking... What is it that you like about the Altec 421H ? When I was kid in the 1980s everything Altec was already considered to be 'long in the tooth': suited for Seeburg extension cabinets but too easy to blow to be suited for bass or PA use.

I sure blew my share of "200 watt" JBL E140s with a bass guitar, never liked their voicing anyway and thought they sounded horrible for anything having to do with human vocals. In the old days I really liked the tone of EVM 15Bs for mid-bass in a PA system (say 100hz to 1000hz), and still like them for bass guitar, ...but again too easy to blow to rely on for regular use: the occasional situation where levels may get intemperate (guest bassist perhaps) will sure risk frying them. ...Sorry for the swerve.

As someone who cut their teeth on 421A's and D140F's I really disliked JBL's offering and though not lived with the E140 series it's more limited frequency response and Xmax of 3.5mm would likely leave me back in the fart zone even when I powered them with a SUNN 2000S (120 watt all tube. I was an Alte 421(A in those days) for tone and never burned or farted one. Those days were low output power tube equipment in the ranges of 40 to 120 watts until the SVT arrived.

 

[Drop1]

That's exactly what I was wondering, I thought he was asking a question yet if he already knows it all, why ask us mere mortals question. If you might have noticed, the more he says the less doubt he leaves.

I asked 1 simple question. A few of you answered it. Others started shoving their opinions in. All I wanted was some recommendations for fairly neutral 15s. I didn't ask for any of the rest of this. At all. People keep telling me what I ought to do when I already know stated I "what" to do.
This thread should have died after you made your recommendations on the first page. Yet here we are in typical tb fashion.
I've stated this this project is for fun and I'm using 215 because I like to feel it yet so few are actually listening. So yeah, I may have been kind of a prick. It's taxing around there sometimes.

 

[Drredplate]

In order to do the experiment you describe here is a suggestion.
Make a cab with a removable back panel
This will allow you to easily add or subtract materials from within the cab.
Make a few removable plates to accommodate. Sealed/ various ports or aperiodic if you desire.
You could even have a selection of variable back plates to accommodate ports etc.
(I don’t have the knowledge to comment on what you should and shouldn’t do)

 

[crazyBassClown]

Others started shoving their opinions in. All I wanted was some recommendations for fairly neutral 15s

Well in my opinion, IF you want fairly neutral 15's and live gigs and absolute volume is not your goal Musical instrument and PA speakers are not the correct choice. Home Stereo speakers are much more neutral in general than any PA or MI speaker.
What makes a speaker suitable for live instrument amplification is high sensitivity as a higher preference than frequency response.
You asked for the opinions and then don't like it when offered and tried to show us all how smart you are and failed miserably.

My final bit of advice is if you have the money to buy professional frequency and phase response equipment just go buy a few 15's and test them all till you get what you want. There are literally dozens or probably hundreds of threads here you could have searched for with 15 inch driver recommendations and avoided all of this.

 

[amper]

I have one beef with Celestion: they don't provide any guidance as far as compatible cabinet design. They don't even say if the speaker is good for sealed or ported applications.

These are screenshots taken this very moment from Celestion's product info page. If you don't know how to use this information to determine whether or not this driver will work in the application you have in mind, you should leave loudspeaker system design to those who do, or at least study the subject until you realize that Celestion has already given you everything they should and can give you to enable you to design a loudspeaker system using this driver.

 

[amper]

Here, Let Me Google That For You:

Loudspeaker System Design Books

Loudspeaker System Design Software

 

[Drredplate]

What you say is correct and software is readily available. But it wouldn’t hurt to say in the product description “ suitable for use in abc type enclosures “ and give a broad cabinet volume range like many other manufacturers

 

[Drredplate]

Just for the record the best alignment for a celestion pulse 15 is
125litres with twin ports 75mm x 142mm

or for a sealed enclosure 70litres sealed