My RS180 MTM Design

[kraigo]

I'm about ready to button mine up. Reverse the polarity on the tweeter or not?

[Jeff B.]

I'm about ready to button mine up. Reverse the polarity on the tweeter or not?

Why do you ask? If you are building my design then you should follow the schematic I posted and keep the tweeter in normal polarity. Reversing it would give you a deep null in the response.
Jeff

[kraigo]

I just wanted to make sure that I wasn't missing anything. Thanks Jeff.

[kraigo]

Well, so much for those baffles (other than as a template). I guess I won't be listening to these tonight.

I wanted to do threaded inserts for the woofers to ease the pain should I have to open them up later. As accurate as I tried to be, it wasn't good enough. Add the super glue to the equation plus stripping out inserts while trying to get them out and you've got quite a mess. They'll be good templates for the next set.

Thank God I held off until everything else was done before gluing them in.

KO

[kraigo]

FWIW, that was a relatively cheap learning experience (I think - haven't priced the baffles yet). It's all part of diving into this hobby. The dog is in no danger of getting kicked (not that she'd ever be).

[djg]

Just use the black sheet metal screws PE sells to mount your drivers on your new baffles. Quite secure, so much easier.

In fact, you could probably save those baffles by knocking out the inserts, drilling a hole at each insert location, and filling with wood dowel. Proceed with pilot holes and sheet metal screws or wood screws.

[kraigo]

Yeah, I've even got the screws around. In fact I'd resigned myself to use them on the tweeter because the screw holes were so close to the edge - too tight, IMO. I'll probably try to salvage the existing baffles. It costs nothing.

Thanks!

KO

[wlg]

Sorry if it's been covered already, but, can the non shielded RS180-4 be used in the series design?
Also is there a reduced bsc crossover so these can be used for near wall placement?

Thanks,
Wayne

[ontariomaximus]

Sorry if it's been covered already, but, can the non shielded RS180-4 be used in the series design?
Also is there a reduced bsc crossover so these can be used for near wall placement?

Thanks,
Wayne

I used the non-shielded 4 ohm version
Can't offer anything about BSC. My front baffle is about 26 inches from the rear wall

[AlexRivera]

Hi All,

I'm trying to input Mr. Bagby's design into his PCD 7 spreadsheet but I'm unable to get rid of what seems to be a cone breakup in the woofer (see picture), which I don't see in his chart.

Should I really care about it, perhaps is not audible?

I think this could be resolved with a notch filter but where do I put it in PCD?

Thanks in advance!

[donradick]

Hi All,

I'm trying to input Mr. Bagby's design into his PCD 7 spreadsheet but I'm unable to get rid of what seems to be a cone breakup in the woofer (see picture), which I don't see in his chart.

Should I really care about it, perhaps is not audible?

I think this could be resolved with a notch filter but where do I put it in PCD?

Thanks in advance!

You are learning!

The crossover "magic" in this design is the .025mH coil between the 20uF and ground.
That creates a LC(R) trap that pushes the breakup nodes way down.
Look at the PCD topology help page. Somewhere there is an inductor for that location.
Everyone else used a notch filter on the RS metal cone drivers, Jeff found a better/simpler way.

[Wolf]

Don- I don't know that an LC is simpler/better than another LC. Both series and parallel are notch filters.
Later,
Wolf

[donradick]

Don- I don't know that an LC is simpler/better than another LC. Both series and parallel are notch filters.
Later,
Wolf

Of course you are right. My point was that I've seen a lot of series and parallel traps to handle breakup modes.
Usually this is done separately from the LP topology
Jeff's solution in this case is elegant.

[Jeff B.]

Of course you are right. My point was that I've seen a lot of series and parallel traps to handle breakup modes.
Usually this is done separately from the LP topology
Jeff's solution in this case is elegant.

Thank you Don. I appreciate being called "elegant"

[donradick]

Jeff -

So glad to hear your voice again.
Looking forward to many more JB creations.