[SpeakerDoc]

I am new here and I just basically want to get these RM40s into good working order as fast as possible.  I also might want to experiment and compare the different tweeter configurations.  It seems to me that an FAQ would be helpful since I'm sure there are many common questions.  I emailed Brian and he gave me a few quick answers, that I will include here.  Thinking again I'm not sure if he wants his current pricing for spare parts made public so I will not include them - is there a parts price list available online somewhere?

Is there already an FAQ for the RM40 by any chance?

Edit:  I hope to collect some facts here that might someday be the basis for an FAQ.

[John Casler]

I am new here and I just basically want to get these RM40s into good working order as fast as possible.  I also might want to experiment and compare the different tweeter configurations.  It seems to me that an FAQ would be helpful since I'm sure there are many common questions.  I emailed Brian and he gave me a few quick answers, that I will include here.  Thinking again I'm not sure if he wants his current pricing for spare parts made public so I will not include them - is there a parts price list available online somewhere?

Is there already an FAQ for the RM40 by any chance?

Most of the pricing for available parts or upgrades is posted in the price list. (might take some searching)

More specific pricing can be obtained by e-mailing Brian, myself, or your dealer.

[SpeakerDoc]

The bass/midbass sounds like it is coming from the floor or just above the floor, then when I stand it moves to the upper woofer.  I'm wondering if the drivers should be in phase or out of phase, since something does not seem right here.

Just checked with a battery, they are in phase as I think they should be.  I wonder if it has something to do with the upper covering more of the midbass since if they were equally driven it would create an virtual center source.

[John Casler]

The bass/midbass sounds like it is coming from the floor or just above the floor, then when I stand it moves to the upper woofer.  I'm wondering if the drivers should be in phase or out of phase, since something does not seem right here.

That is indeed strange. 

Some time ago someone suggested "swapping" the woofers and placing the low bass woof up top and vice versa.

This, according to Brian would have resulted in less LOW BASS.  Never heard of anyone except the OP doing it, but if your friend was a tweaker he may have tried it.

Yes, the WOOFERS should be in phase which can be checked by applying a 9v battery to the bass leads (these are the upper binding posts) for a quick second.

Both woofs should move out or in at the same time during the test.

[SpeakerDoc]

Thanks for the reply, I did check with a battery and they are in phase.  They are sounding good, but this just seems odd in the bass and consistent across several recordings.

Are the woofers directly in parallel or is there a resistor in series as I thought I read somewhere?

I also heard of a double stack magnet, is there a crossover difference for use with that woofer driver?

[John Casler]

Thanks for the reply, I did check with a battery and they are in phase.  They are sounding good, but this just seems odd in the bass and consistent across several recordings.

Are the woofers directly in parallel or is there a resistor in series as I thought I read somewhere?

I also heard of a double stack magnet, is there a crossover difference for use with that woofer driver?

I'll leave those questions to Brian to answer.

RM40s have not been a "static" design and have been improved and upgraded a couple times since 2002 when introduced.
 

[SpeakerDoc]

I removed the woofers in order to reglue the gasket on one and determine the type of the other.
Both magnet structures are covered in modelling clay, both have woven cones and look identical.
Pushing the clay away in one area reveals a double stacked magnet measured the total magnet
stack height at 1.5".

Can anyone identify these woofers?

One seems to have roughly a .5" hole in the center pole and the other 5/8".

[John Casler]

I removed the woofers in order to reglue the gasket on one and determine the type of the other.
Both magnet structures are covered in modelling clay, both have woven cones and look identical.
Pushing the clay away in one area reveals a double stacked magnet measured the total magnet
stack height at 1.5".

Can anyone identify these woofers?

One seems to have roughly a .5" hole in the center pole and the other 5/8".

That sounds like the stock woofers Brian uses and has manufactured for him. They are not commerically available. 

He does not add modeling clay so it sounds like the previous owner had some fun with damping materials.

Brian does add Dynamat to the woofer basket.

Both Woofers in the newer models should look exactly the same, but are magnetized to different strengths, so make sure you know which is which.

If yours has different sized phase plugs then you may need to consult Brian as to the difference.  I have not seen a phase plug 1/2 inch before on a 10".

[SpeakerDoc]

That sounds like the stock woofers Brian uses and has manufactured for him. They are not commerically available. 

If yours has different sized phase plugs then you may need to consult Brian as to the difference.  I have not seen a phase plug 1/2 inch before on a 10".

Sorry, the hole on the back center of the magnet structure is that size not the phase plug.

And yes there is also Dynamat.

The wiring is silver shielded, do you know the brand off hand?

[ctviggen]

Isn't it Analysis Plus? 

[John Casler]

Isn't it Analysis Plus?

Depending on construction date it could be Analysis Plus or Bolder.

Bolder is more current.

[SpeakerDoc]

The upper woofer is about 2.5 dB more efficient; is it the upper that
should have the stronger magnets?  I'm wondering if they were ever
reversed.

[ctviggen]

I believe it is the upper, or at least I seem to remember replacing that one.  The upper should be the mid-woofer.  You may be able to play some low frequencies (test tones would work well if you have them) and compare the two woofers' outputs.  The upper, mid-woofer should be more prominent as the frequencies increase (and vice versa).

[SpeakerDoc]

I believe it is the upper, or at least I seem to remember replacing that one.  The upper should be the mid-woofer.  You may be able to play some low frequencies (test tones would work well if you have them) and compare the two woofers' outputs.  The upper, mid-woofer should be more prominent as the frequencies increase (and vice versa).

Yes I do have test tones, warble tones, band limited noise etc. 

Edit:  Just spoke to Brian and he confirms that the more efficient woofer
goes at the top and it should be marked .3.  The less efficient woofer
goes at the bottom and is marked .4.  I cannot see any markings
since these are covered in modelling clay.

[SpeakerDoc]

I pulled the 4 midrange panels and found that the top
one is 2.7 ohms DC resistance.  The other 3 are about
4.7 ohms.  The top panel looks identical but newer was
there a revision in the panels?  Is this the correct
configuration or should they all be the same? 
I was very careful in taking the measurements and made
sure that there were no shorts across the traces where
the contact is made.

[Brian Cheney]

It appears the top panel has been replaced.  The 4.5 Ohm panels have been unavailable for about 5 years.  You can add a 2 Ohm series resistor to the top panel to return the array to its former impedance of 4.6 Ohms.

[SpeakerDoc]

Thanks for the info Brian, hope you're having a nice Memorial Day ...

[SpeakerDoc]

I've found that the screws for the input terminals on the
midrange panels are showing very minor signs of corrosion.

I'm going to replace the hardware with 1/4" stainless steel
screws and SS nuts, these will not stick out as much but
are certainly long enough.  I determined that the screws
do not carry the signal current since there is no connection
on the other side.  The terminal lugs conduct straight to
the metal on the film membrane and I plan to use DeOxit
Red there as long as this is safe.

It looks like the point of the nuts may almost touch the
metal frame of the panel if they point straight at it.
I spoke to Brian about this and he said to position the
flat side of the nut toward the frame to avoid shorts.

[SpeakerDoc]

Several of the panels seem to be sunk into the baffle by
about 1/16", I'm guessing due to the foam gasket
becoming over compressed over the years.  I plan to replace
them with 1/8" foam material in order to bring them flush.

[Brax]

I also replaced the foam gaskets while I had mine apart and added more mounting screws for the panels by drilling out the unused holes in the panel’s flange. I was very careful to cover and tap off the driver area because if a metal chip gets in there, I don’t think you would ever be able to get it out.

When I pulled all the mid panels off my RM40s I also upgraded the fill behind the mid panels. While you have the mid panels out, you should consider this also. The tweak is to replace the fiberglass stuffing with lamb’s wool. Not a huge improvment, but cheap enough to give it a try. This can be purchased from Madisound and you only do it in the mid panel cavity. The other thing to look for is that the mid panel cavity is still sealed from the woofer cavity. To be on the safe side, I added a bead of rope caulk to all the inside seams. With a cabinet of this age and all the moves it has seen it’s possible to have broken the seal somewhere.

I am considering buying a few spare mid panels. I don’t ever plan on replacing my VMPS speakers (well maybe upgrading the center to an RM40 once my HT room get built) and the supply of these drivers is limited to what Brian has in stock. With 13 panels total in my system one may just go or get damaged somewhere down the line.