Simple Model 19 plans available

[martyh45]

I finished a simple(ish) 1 box plan for the M19 clones. They are available for download at http://www.filecrunch.com/file/19n in the form of a 3 page PDF file. It prints well to 8-1/2" x 11" paper on my home printer.

The goal was to duplicate the sound of the originals in a cabinet that is easier to build. Height, driver location and offsets match the original design. I did not include the 2? base of the original but there is enough material left over from the three sheets of MDF to build them. Sorry, you need to wait 15 seconds before you can hit the download button. Link to pdf

[sekess]

Hi MartyH45,
Thanks for the download. I have a question about the 2.5"x11" slot. Is that just a rectangular opening cut into the front? There is no length (depth) to it?

I've never seen a Model 19. So, I am not familiar with the construction of one.

Thanks,
Steve

[martyh45]

Hi,
Yes, that is just a slot. The original plans can be found at http://home.earthlink.net/~jmarkwart/id13.html. They have more information on stuffing etc. You can also find the crossover schematic at the same site.
Link to original plans

[martyh45]

Hi GM,
Thanks for the inpu. It should be a simple matter to add the port to the interior. I am thinking a 2-3/4? extension around the cutout in the horn shelf should be close but I am not sure if it would be better to make it a bit longer so that the volume inside the port matches the original or to keep the length and entrance exit areas equal. What do you think?
Thanks,
M

[martyh45]

Ummmm..... that shoud read "thanks for the input" but I apreciate the the inpu too, just didn't think to mention it the first time

[sekess]

Thanks everyone. And thanks for the picture gamalot. The model 19 seems very well built -- especially in the top section.

That's interesting about the slot opening though. I was going to eventually build a seperate simple vented box for the 416 woofer and build a seperate top section for the horn(I would then just set the horn box on top of the 416 cabinet). I was trying to attain the internal box volume and the port area and length.
The box volume I see is around 9.4 cubic feet (from another thread). And if I am to understand correctly from this thread, the port could just be a 2.5" x 11" opening without any length? Is this correct? Or, is there some other porting factor involved here?
Thanks,
Steve

[gamalot]

I would certainly rely upon the info from GM on this.
My thought is that the vent you see on the front baffle of the 19 Factory cabinets will work perfectly as long as you build the cabinets with the exact same internal volumes, build two seperated boxes and open them to each other just like pictured.

I don't do cabinet designs but I do believe once you change the basic design then all bets are off as far as porting size.

Allow GM to chime in with his thoughts on this but I would not consider the rectangular ports dimensions for cabinets other then those pictured.

Gary

[martyh45]

I believe GM was talking about the space between the top and bottom boxes in the original plan. The effect should be easy to simulate in the simple box by adding an extension around the cutout in the horn shelf. The vent to the outside air is the same as the original.

[gamalot]

I think there is some confussion here!

Factory 19s have one port to the out side air and it is 2.5" W X 11" H.
If you are considering the cutout between the top and bottom boxes as a port, it is NOT to the O/S air. It merely provides additional interior volume to the mix by opening the two boxes to oneanother.

I think for a single box design the ports would be much simpler with 4" holes and port tubes that could be adjusted to suit user desires or tune to particular cabinet frequencies.
Keep in mind that once a hole is cut it is pretty hard to fill it in if this becomes necessary. Port tubes are inexpensive and infinately adjustable while rectangular ones are not quite as easy to adjust or tune.


Gary

[martyh45]

According to what I have gotten out of GM?s post, the opening between the boxes may have an effect on the sound beyond the simple addition of volume. That makes sense to me because of some of the double bass reflex designs I have seen. If this is the case, then it should be included if the goal is to get as close as possible to the same sound. Even the location of the vent on the panel can have an effect but it is possible to tune to the same frequency using round ports of whatever size you like. It is also possible to make a bigger box and tune it differently to improve the performance in certain areas like group delay, flatness of response and LF cutoff but you would be changing the balance of the whole.