Replacing Drivers, Redesigning XO

[TNRRClassic]

I am going to reuse the cabinets and woofer from a NOS pair of Cerwin Vega VS120's that I was given. I am not really impressed with the mid and tweeter, but would like to reuse the cabinet. I was planning to do some minor cutting and install a RS150S and a RS28A, and redesign the crossover. Up until now, I have not done a crossover design of this magnitude. These aluminium cone speakers seem to call for higher order crossovers than I am accustomed to, and I want to account for everything I can in the crossover. I would really like to use the RS drivers as they are what I am using in the Modula MTM and Modula MT projects that I am working up. I am embarassed to say that I have always used freeware crossover design software, and don't have anything too useful. Thank you for any advice you might have.

[cjd]

What are the box dimensions?

There's a thread with a handful of crossover options for a TM with RS150S-8 and RS28A (or Seas 27TDFC). I'll try to find it.

here it is.

C

[TNRRClassic]

enclosure dimensions

The box is 32"H x 16.5"W x 14.75"D, and is 3/4" materiel. After I install the new tweeter, it would be vertically centred 4 1/8" from the top of the enclosure and horizontally offset 1/2" to the right of the centreline looking on from the front. The new woofer would be vertically centred 9 7/16" from the top of the enclosure and also be horizontally offset 1/2" to the right of the centreline looking on from the front. I could adjust the horizontal orientation of the drivers to some degree when I enlarge the mounting holes, so that measurement is not necessarily fixed, should there be a more optimum placement. The enclosure is double ported to the rear with two 4" ports.

[cjd]

Meh. You're trying to re-use the least likely part to be re-usable. Not at all getting a clear picture now. Can you sketch something up? What exactly are you looking for from us?

FWIW freeware is not a sign of anything other than the choice of a software developer. Some superb tools in this arena are free.

C

[TNRRClassic]

Sorry as to not make myself more clear. I am trying to conduct a feasability study here. The basic question I am asking is, using the RS line of drivers, can I replace the midrange and tweeter in the given enclosure without having to resort to a crossover on the order of a Jon Marsh special? With the baffle width, enclosure volume, and other issues, is there any potential expectation of success, or is this a colossal waste of time and effort?

I am not expecting something in the realm of a $5000 speaker, nor even a $1000 speaker, but I would like some imput. I am simply asking for the more experienced members to kick in their opinion and/or ideas.

[Dennis H]

The biggest problem is the 16" cabinet width. Most of the 'stock' designs here are for a narrower cabinet so the baffle step compensation will be different. You'd need to modify the crossover for best results with the wider cabinet.

[cjd]

Ahh. Well. Starting with the box is going to work best only if you get lucky. So not impossible, but... it's a strike against the thought.

None of these drivers are exactly a walk in the park to work with, so aren't beginner friendly. The RS150 is the most forgiving, but it's still picky. Another strike. And triply so if you're hoping to re-use an existing woofer, since it is (at the moment) a relative unknown and may or may not work well with the RS drivers. Not sure if you've got a 3-way or 2-way on your hands. Box size is big...

The way a lot of those are put together is, well... kinda crazy. Your dislikes may have nothing at all to do with the drivers, and everything to do with the implementation.

So, I see a large potential for disappointment. And very possibly for learning quite a bit, which is not a bad thing at all if you're interested in that. A lot of the learning may be possible with the drivers already in the speaker.

If you have measurement equipment and can get accurate results, you've a LOT more power to get adequate results (or better) - in part because you can then model and post/ask questions along the learning curve.

Otherwise... well, IMHO it's time to accept them for what they are, and find an existing project that meets the desires you were hoping these might manage to meet.

C