[traderz]

I have a pair of RM/X and I believe I burned the tweeter on one of them. The potentiometer in the back gives no resistance and furthermore it is loose, I can push it in an inch or so. Few days later woofer and midrange stopped working as well. Anyone familiar with anybody in SE Florida who would be able to take care of this? Thanks!

[Brax]

Your tweeter is probable okay, the pot is more than likely shot though. You can get new pots at madisound.com

[traderz]

Yes, tweeter looks fine and woofers are playing when wired only to the upper binding posts. Pot? Do you mean the L-pad? I checked the madisound.com, but couldn't find any VMPS parts there. Do you know where to buy an L-pad for the RM/X? Could you, please send the link? Thanks!

[TAFKA Steve]

I also have a pair of RM/X's.  Parts Express #260-265 appeared to be the L-pad used when I opened up my speakers.  It is a mono 8 ohm 100 watt unit with a 1" shaft length.  You'll need to keep the small knob from your old L-pad when you remove it, as the knob on the PE part is much larger and won't fit in the small cabinet recessed hole.  Your L-pad is also missing the locking nut that held it to the cabinet, which is why you can push the L-pad into the cabinet leading to possible shorted wires and no sound from some drivers.

To do the replacement, carefully lay the 350 lb. speaker on its side on top of large cushions covered with a soft cloth to protect the ebony finish.  Remove both front and side woofer grills, then remove the front woofer first.  Note the wire connections to the woofer terminals before detaching the wires.  Remove some stuffing.  Remove screws from the side woofer, then stick your hand through the front hole and push the side woofer out by pressing up on the back of
the magnet.   Detach side woofer wires and remove the rest of the stuffing.  Now you have enough room to use tools and a light through both woofer holes to locate the bad L-pad. 
Mark the wires on the bad L-pad and mark their respective locations on the replacement.  Clip the wires closely to the soldered terminals of the bad part.  You should be able to remove the old part at this point.  Use wire strippers to remove 3/4" of insulation from each cut wire end.  Insert the new L-pad with one nut on its shaft and use that nut to adjust the depth of the shaft protruding from the rear of the cabinet, then add the second nut on the rear and the saved old knob to lock it to the cabinet.  Attach and solder wires to the terminals, then attach your speaker cables and do a sound check to make sure the drivers and L-pad are working (don't short your loose woofer wires when you do this).  Replace stuffing, attach woofer wires while remounting woofers and you should be ready to go.

[TAFKA Steve]

I forgot to mention the flat washer and the lock washer on the L-pad shaft .  Going from the outside of the cabinet to the inside, the parts on the shaft should be knob/nut/ flat washer/ cabinet/lock washer/nut.

[Brax]

I called it a Pot short for Potentiometer.

http://www.madisoundspeakerstore.com/l-pads-attenuators/fostex-r80b-100w-l-pad/

[traderz]

Steve, Brax, great info! Thanks! I ordered PE 260-265, will attempt to fix it myself.

[traderz]

I just replaced the blown L-pad with Parts Express #260-265. Woofers and midrange are working fine, but the tweeter is still dead. Nothing else in the cabinet seems to be blown out, the tweeter itself looks undamaged but I can't think of anything else other than replacing the tweeter. Anybody knows of where to purchase a new tweeter and how to install it? Thanks!

[James Romeyn]

I just replaced the blown L-pad with Parts Express #260-265. Woofers and midrange are working fine, but the tweeter is still dead. Nothing else in the cabinet seems to be blown out, the tweeter itself looks undamaged but I can't think of anything else other than replacing the tweeter. Anybody knows of where to purchase a new tweeter and how to install it? Thanks!

You could test the tweeter with a 9V battery across the inputs...you should hear a loud "click" sound.  Alternately, connect music program from power amp directly to the tweeter.  Just make sure the level is very low and make sure the music program is very light in bass energy.  To test conclusively, remove at least one lead from the crossover to the tweeter to positively insure you test the tweeter all by itself. 

You don't want to install a new tweeter only to find out the original tweeter worked fine and the problem is somewhere else. 

Tweeter is Auram Cantus IIRC, sorry model unknown, but likely still available for a couple C notes max.

L-pad maintains constant impedance on the tweeter regardless the rotation (IIRC L-pad comprises two pots, one each series and parallel, which change in opposite magnitude...while one pot increases in magnitude the other pot decreases in magnitude).  If it was a simple pot the impedance and hence crossover pole would change with rotation.

Still remember Brian had three X's early 00s, second time he won Best of High End Award, shared with Bongiorno's Trinaural Processor.  That was Brian's last CES.  They promised him he'd never win that award again.         

[Rocket]

Hi,

Did you check to see if the ribbon is torn.  Try swapping the tweeter with the one from the working speaker.

Good luck with the repair of your speaker.

Regards Rod

[Stimpy]

Brian apparently used Parts Express quite often as a source for drivers.  And since Parts Express is a dealer for Aurum Cantus, I'd contact them, to determine the exact RMX tweeter to purchase.  Parts Express even sells replacement Aurum ribbon 'diaphragms'.  Buying a replacement diaphragm instead of a whole new tweeter, could save you some decent money, if you've willing to repair the tweeter yourself.  Just make sure to remove and test the tweeter(s) impedance first, with a multimeter, to truly determine that the tweeter is dead.

http://www.parts-express.com/brand/aurum-cantus/360

http://www.parts-express.com/contact-us

Plus awesome speakers!  I'd love to just hear a pair, let alone dream of owning a pair!  Brian's most visually impressive single speaker design IMHO.   They look as if they could be the RM30s father, that is, if that father was Darth Vader!!!      "RM, I am your Father!".   


Good luck!

[James Romeyn]

I'm pretty sure there is replacement ribbon panel for that tweeter.  Brian and I frequently listened to tweeters direct-coupled to amps sans crossover.  I'd not be concerned about such audio test damaging the tweeter if you:

• Insure music program does not have intense bass energy.
• Insure all system components are fully on before connecting the tweeter.
• Insure speaker cables never short.
• Insure volume is at zero, then connect tweeter, then start music source, then slowly advance volume, listen for music (stop at moderate level if no music is heard, that tweeter is high sensitivity), then disconnect tweeter (insure speaker cables don't short), then turn off amp.

[Brax]

I had a tweeter stop working on one of my RM-2s. The tweeter would play but only very softly, you needed to put your ear next to it to hear it. It ended up being a "Open Cap" as Brian put it. Brian sent me a replacement capacitor and I changed it out in the speaker which solved the problem.

Also ensure you have the L-pad hooked up correctly.

[TAFKA Steve]

Hi Traderz,

I am sorry to hear that you still do not have a tweeter signal.  The problem can be either an open tweeter capacitor or the tweeter itself.  For your sake, I hope it is the former rather than the latter. 

First, compare  the front of both your tweeters with a flashlight and see if the vertical aluminum ribbon (with evenly spaced  horizontal folds like a rippled potato chip) on the bad one looks similar to the working one.  If it is blown, the ribbon will separate vertically to two pieces and collapse like a folded foil fuse.  The tweeter is an Aurum Cantus G2Si (Parts Express #276-400 listed at $127.88) and the replacement ribbon is also available from Parts Express for $5 (sorry I don't know the part number offhand), along with downloadable instructions.  Warning, I had extreme difficulty replacing the ribbon due to the strong magnets pulling my magnetized tools in awkward directions.  Also it is difficult to center the ribbon evenly in the gap.  Order several replacement ribbons if you choose to do this, because you'll probably ruin the first one.  Ultimately, I decided to just replace the entire tweeter, but this poses several problems (which I'll discuss below).

If the ribbon is not blown, it is likely that the crossover capacitor for the tweeter has opened and failed.  If you have the reddish capacitors in your crossover, these are TRT Dynamicaps (available from Parts Connexion and Michael Percy Audio).  I dunno if Brian ever built RM/Xs with the cheaper Auricaps.  In any case, look for the single cap (not the midrange multiple bundle) that is wired between the lower positive midrange/tweeter binding post and the tweeter L-pad.  It should have the value in microFarads (.XX) handwritten in black magic marker on it.  You need a digital multimeter with a capacitance measuring function or a capacitance bridge to check that it still yields the written value (it can only be measured if at least one end is detached from the speaker crossover).  If it isn't marked, ask for this value at this board because it was a standard parallel 2nd order 7kHz crossover used for this tweeter on several VMPS model (I don't remember the value of mine).  If the cap is bad, you can cut it out and solder a replacement in, but note that these take a lot of hours of play to burn-in before the sound opens up.

If you decide you need to replace the tweeter itself, consider the following.  Aurum Cantus has changed the G2Si, both physically and sonically.  I was so surprised that I thought the older tweeters might have been Founteks, but I was wrong.  The vertically-tiltable tweeter enclosure of the RM/X is milled from a solid block of wood and this causes a tweeter replacement problem unique to this VMPS model.  My original tweeters have a flat rear housing, but the newer G2Si has an extra protrusion in the rear that makes mounting the new tweeter flush to the enclosure impossible without sticking out an additional 3/16".  Unless Brian switched over to the newer tweeters at some point during the RM/X manufacturing run and deepened the milling of the hole in the enclosure, you would need to mill out the recess in the tweeter enclosure to flush mount the new tweeter (I don't have the tools or woodworking skills to do this).  Second the newer G2Si has a lower efficiency than the older version (I measure a 6 dB decrease in efficiency).  Third, the newer tweeters measure with a smoother frequency response and omit the 12 kHz peak that I found annoying  in both of my older tweeters.  The upshot is that I replaced both of my tweeters and you might have to do the same. 

To replace the tweeter or tweeter ribbon, you have to remove the foam "dehorning mask" from the front.  This is messy because it was applied with spray adhesive. Then remove the four outer phillips screws from the tweeter front plate and pull the tweeter out of its enclosure.  Note the wire colors and which goes to which post on the tweeter rear, then cut the wires close to the posts and strip the wires.  Remove the tweeter. 

If you attempt to replace the ribbon, remove the face plate via the four Hex head screws and follow the online instructions from Parts Express, then resolder the wires to the posts (don't use too much heat!) and remount the tweeter.

If you are replacing the tweeter, the screw posts on the new tweeter are too long and need to be shortened to fit the hole in the enclosure.  I did this with large wire cutters, but a rotary cutting bit on a drill would be more suitable.  In either case, avoid twisting or bending the screw post, because this can detach the internal wires which are barely contacting the posts inside the tweeter's plastic housing (you'll end up with a dead tweeter with an intact ribbon and there is no way to fix this as opening the potted plastic housing destroys the tweeter).  Remove the nuts on the posts on the new tweeter before shortening the posts and don't replace them after shortening.  Tin the shortened screw posts with solder (be careful using too much heat because this may also cause the internal wiring contacts to fail).  The outer wires are then soldered to the posts and directed to run sideways because they need to clear the extra protrusion in the rear housing when you remount the tweeter to the enclosure (if you did not remill the enclosure to deepen it, the protrusion should fit directly against the wood in the hole without binding the wiring between them).  The mounting screws must be evenly tightened to avoid tilting the tweeter housing.  You can try reattaching the dehorning foam, but after measuring and listening to mine with and without the foam, I decided to go without the foam.  I have not tried attaching waveguides to my tweeters, but note that this would reduce their efficiency further.

BTW, while you have your speakers open you should spray the inside of both L-pads with Caig Deoxit D5 (Parts Express #341-200) , expecially the older midrange L-pad, followed by rotating the controls back and forth several times.

I'll try to check back later to see if you need additional help, but I'll be unavailable May 30-June 1 due to  T.H.E. Show at Newport Beach.  Hopefully, others like James Romeyn and John Casler can chime in with additional help.  Good luck.

Steve     

     

[TAFKA Steve]

Here's a side view of the original RM/X tweeter (left) and the new Aurum Cantus G2Si (right).  On the right, note the extra height added by the raised rectangle on the housing and the length of the uncut screw posts.  The magnets, housings, and the faceplate thicknesses are also different.  The reduced magnet size may account for the lower sensitivity.  I do not know if the internal impedance matching transformer has been changed.





Here's a comparison view from the bottom.  The positive terminals on each unit are on the left.  Again, note the differences.



The G2Si is shipped with ring lugs and top nuts to tighten down the rings.  These need to be removed before you shorten the screw posts.



The G2Si screw posts are ready to be shortened and soldered.  Do not remove the bottom nuts, but tin and solder the tweeter wires to the remaining screw threads next to the bottom nut.

Hope these pictures help.

Steve

[traderz]

The tweeter is fine, I've just replaced the other L-pad, no sound from the tweeter. So I pulled out the capacitor and it is blown on the side that was glued to the cabinet, so I couldn't see it while it was still attached to the cabinet. This is the photo of it. The only inscription on it is 1.3.. nothing else.... Anybody knows what is this and where can I buy it? Thanks guys!

[Stimpy]

The tweeter is fine, I've just replaced the other L-pad, no sound from the tweeter. So I pulled out the capacitor and it is blown on the side that was glued to the cabinet, so I couldn't see it while it was still attached to the cabinet. This is the photo of it. The only inscription on it is 1.3.. nothing else.... Anybody knows what is this and where can I buy it? Thanks guys!

I would assume that the "1.3" marking is the capacitor value, 1.3uf.  Brian used several brands of capacitors, but mainly advertised Solen, AuriCaps and TRT DynaCaps.

http://pointillistic.com/vmps-audio/pricing.htm

http://pointillistic.com/vmps-audio/technical.htm

Considering their cost, I would hope that the RM/X used TRT's, but that's just a guess on my part.  TRT capacitors can be ordered directly from the manufacturer.  Hopefully, they can match Brian's value requirements?  If not, you might want to order matched pairs of capacitors, a new set for each speaker.

TRT
408 Mason Rd.
Vista CA 92084 USA
Email:

trt-wonder@cox.net

http://www.trt-wonder.com/index.html

The TRT StealthCaps sound interesting too.  It sounds like they'd be a step-up from the TRT DynaCaps.  But, their price is a step-up as well!

Hopefully someone with more direct knowledge of the RM/X will respond too.  I hope.  I do not own RM/X
speakers, and I'm only relaying info that I've read here and elsewhere!

Good luck!

[Stimpy]

What Steve said!!!      

http://www.partsconnexion.com/capacitor_film_dynamicap.html

http://www.percyaudio.com/

http://www.percyaudio.com/Catalog.pdf

If the ribbon is not blown, it is likely that the crossover capacitor for the tweeter has opened and failed.  If you have the reddish capacitors in your crossover, these are TRT Dynamicaps (available from Parts Connexion and Michael Percy Audio).  I dunno if Brian ever built RM/Xs with the cheaper Auricaps.  In any case, look for the single cap (not the midrange multiple bundle) that is wired between the lower positive midrange/tweeter binding post and the tweeter L-pad.  It should have the value in microFarads (.XX) handwritten in black magic marker on it.  You need a digital multimeter with a capacitance measuring function or a capacitance bridge to check that it still yields the written value (it can only be measured if at least one end is detached from the speaker crossover).  If it isn't marked, ask for this value at this board because it was a standard parallel 2nd order 7kHz crossover used for this tweeter on several VMPS model (I don't remember the value of mine).  If the cap is bad, you can cut it out and solder a replacement in, but note that these take a lot of hours of play to burn-in before the sound opens up.

[traderz]

Stimpy, yes, I followed Steve's instructions to the letter. The problem is that the TRT Dynamicap 1.3uF capacitor is not available for sale on any of the suggested web stores. So the only route is to try to custom order them directly from the manufacturer. And yes, they seem to have an upgrade to Dynamicaps, the TRT StealthCaps, so I'll probably try these and replace them in both speakers.

[Stimpy]

Stimpy, yes, I followed Steve's instructions to the letter. The problem is that the TRT Dynamicap 1.3uF capacitor is not available for sale on any of the suggested web stores. So the only route is to try to custom order them directly from the manufacturer. And yes, they seem to have an upgrade to Dynamicaps, the TRT StealthCaps, so I'll probably try these and replace them in both speakers.

As I'm sure you know, most electronic parts are sold at a stated value, with a tolerance stated for that value.  I've seen capacitors sold with tolerances varying from 1%, to 5%, or to 10% and higher.  As such, TRT's 1.0uf cap, with it's tolerance, probably was what was used in your RM/X.  And from what I've read about Brian, the 1.3uf value, that's written on your cap, was the actual measured value of the cap.  Brian's hand writing too.  Maybe recorded so that Brian could match specific cap sets into pairs of speakers. 

So, you'd probably be safe ordering TRT's 1.0 cap, for your RM/X.  But, maybe contact TRT is see if they can provide a cap that measures exactly at 1.3uf?  Also, you could build match sets of caps, using bypass capacitors, to build up to 1.3uf, for each speaker.  Nothing wrong in doing that.