[Brax]

I have an older set of RM-40s w/TRT caps and spiral tweeters. I am gather the necessary components to rebuild these great speakers and bring them to the next level. Here is what I plan to do.

1) Midwoofer upgrade
2) Vitrifying the PR
3) Check and reseal the Neo pannel enclosure
4) replace stuffing in pannel enclosure with lamb's wool
5) reseal all drivers with 1/8" speaker foam seal
6) add internal bracing to cabinet

I do have a few questions,

1) Is adding damping foam to bass enclosure or pannel enclosure worth the expense?
2) if so, how much is needed?
3) how much lamb's wool per speaker?

Is there something I missed or any advice that can be given on these upgrades?

John C., I'll be calling next week to order the midwoofers.

[john1970]

Brax,

I don't know if it is possible, but I would upgrade the ribbon tweeter if it is at all possible.  Hopefully, John or Brian can let you know if this is possible.

Best,

John

[Brian Cheney]

Replacing the spirals with the FST requires considerable cutting of the 1.5" thick front baffle.  If you can do that the upgrade is worthwhile.

About 3lbs total of wool are needed for the subenclosures.  The crossovers require an additional cap when the midwoofer upgrade is done.  Everything else is straightforward.

[Brax]

I would probably wait on the FST upgrade, at $400 a little too much right now with all the upgrades (to include a new Per/pro). The cutting would be no problem, I am pretty handy at woodworking, so this will have to wait until round two.

[Early B.]

Brax --

I'm interested in how you're gonna add internal bracing to the cabinets. I would assume the RM40 is already well braced, although I haven't seen a schematic. Where will you place the braces? What impact will it have on the internal volume? What benefits do you anticipate?

Thanks.

[Brax]

Early B,

I have an older version of the RM-40, the newer speakers are well braced. Reading past posts, they used 1" hardwood dowels cut to a tight fit to the internal cabinet. Then "pounded" into place. One X brace (a dowel going both front to back and one side to side) below the mid woofer and one above the main woofer. Posters that have done this, say it does improve the bass.

As for the Blackhole 5, I read that Brain recommends placeing it behind the mid driver enclosure on the sides of the cabinet. I assumed it would be installed in the cabinet near each woofer but this may not be the case. I'd like a better description on where the BH5 should go.

I also read that on older versions of the 40, you should check to be sure the mid driver enclosure is air tight, I can see where if it were not, the pressure from the woofers would effect the Neo panels. If you are going to remove the Panels and tweeters to seal this enclosure, you might as well replace the fiberglass with lambs wool, it's cheap and easy at this point. I just wonder if using a small tube of silicone would be easier than trying to get a caulking gun in there. I think Brain also mentioned rope caulk, that might be the easiest to use.

[John Casler]

I have an older set of RM-40s w/TRT caps and spiral tweeters. I am gather the necessary components to rebuild these great speakers and bring them to the next level. Here is what I plan to do.

1) Midwoofer upgrade
2) Vitrifying the PR
3) Check and reseal the Neo pannel enclosure
4) replace stuffing in pannel enclosure with lamb's wool
5) reseal all drivers with 1/8" speaker foam seal
6) add internal bracing to cabinet

I do have a few questions,

1) Is adding damping foam to bass enclosure or pannel enclosure worth the expense?
2) if so, how much is needed?
3) how much lamb's wool per speaker?

Is there something I missed or any advice that can be given on these upgrades?

John C., I'll be calling next week to order the midwoofers.

Look forward to talking to you, and you might want to consider one other "upgrade".

If you're going to be on the inside of that speaker pair, you might want to re-wire it for the D-OXO.

This would make it an RM40 SDE, and for a pretty reasonable price make it sound about as good as any new RM40.

The good thing is B, can program the D-OXO for the "spiral ribbon" and wring as much out of the SRT (Spiral Ribbon Tweeter) as can be had. 

[Brax]

John,

I won't be upgrading to the D-OXO. I wouldn't mind upgrading to the FST but that will have to wait. does the FST upgrade also require a cap change?

After this round of upgrades I need to save my pennies for a LRC (or bigger VMPS center).

I pulled off one of the Neo Panels to take a look inside. Those small screws have got to go! A couple are bent and half stripped. I will redrill the screw holes in the panels for a #8 socket head wood screw.

I picked up the glue for the PR and some rope caulk to seal the mid driver enclosure. Still need to order the wool and screws from Madisound, then then some new speaker gasket material from Partsexpress.

Still looking for feedback on dampening material (BH5 or similar) for the woofers and or mid driver enclousure.

[Brax]

I did a search on this board for Black Hole 5 but the results are a little fuzzy.

Is it (4) 12" x 18" sheets per speaker or per pair? I have seen it both ways on this forum.

If it were per pair, then I assume you would cut each sheet in half creating 9" x 12" pieces. Two of these pieces on each side of the speaker in the middle of the cabinet basicly covering 9" x 24" of the sidewall on each side.

If it were 4 sheets per cabinet, same as above but the coverage would be 12" x 36" of the sidewall of each speaker.

At 4 sheets per speaker that would come to $180 each, is it worth the money?

[audiochef]

Hi Brax,
at Parts Exress the 1 and a quarter inch sonic barrier 18x24 inch sheets are $24.93 each. Yes it's worth the time, money and effort.

[John Casler]

I did a search on this board for Black Hole 5 but the results are a little fuzzy.

Is it (4) 12" x 18" sheets per speaker or per pair? I have seen it both ways on this forum.

If it were per pair, then I assume you would cut each sheet in half creating 9" x 12" pieces. Two of these pieces on each side of the speaker in the middle of the cabinet basicly covering 9" x 24" of the sidewall on each side.

If it were 4 sheets per cabinet, same as above but the coverage would be 12" x 36" of the sidewall of each speaker.

At 4 sheets per speaker that would come to $180 each, is it worth the money?

This is from what B, had me post to the Price List:

Suggested sheets for the following speakers (sheets per cabinet)

RM 40 (4)
RM 30 (2)
RM 2 (2)
626 (1/2)
Subwoofer (any) 2
RM1a (2)
LRC (1)

[Tyson]

Just curious, if the mid-panels subenclosure is not airtight, what would the effect be on the mid panels?

[Brax]

John,

Here's why I was asking. In the first thread, john1970 said he ordered 4 sheets of BH5 for his RM40s. Harvey also stated he ordered 4 sheets for his 40s.

http://www.audiocircle.com/index.php?topic=30620.0

http://www.audiocircle.com/index.php?topic=38311.0

You posted once that the SR71 upgrade was bases on 4 sheets in an answer to a Poster.

http://www.audiocircle.com/index.php?topic=25126.0

If it takes 4 per then that is what it is, just wanted to clear up my confusion. From what I have read, the BH5 is added to eliminate the cabinet resonance and is placed on the sidewalls at the center of the cabinet. With my limited budget (2 kids in college) I need to watch my spending. I am going to add the internal braces when I do the midwoofer upgrade and I know it would be easier to add the BH5 before the braces. It's a cost verus benefit issue.

Audiochef,

From what I have read, an air leak in the midwoofer cabinet created back pressure from the woofers on the panels causing distortion

[Brax]

I have come up with a bracing method that I think may work better than the wood dowels.

I have purchased some 11/16 steel hex bars. I will tap both ends and put in 3/8 hex bolts withy lock nuts and washers. Then I can reach deep into the cabinet (toward the middle) and expand them like turnbuckles but in a spreading motion. I will epoxy the end of the bolts so they bond to the sidewalls. I may even coat them with a compound similar to plastic dip once installed. The advantage of this is I can brace the cabinet from side to side near the middle where it is most needed. The hex bars are small enough not to take up much interior cabinet space and are solid steel so they will not "ring".

I'll post the results once I complete the project.

[rblnr]

Hi Brax,
at Parts Exress the 1 and a quarter inch sonic barrier 18x24 inch sheets are $24.93 each. Yes it's worth the time, money and effort.

You used the 1 /1/4"?  BH is no longer avail.  And where did you put it exactly?  thx.

[inRMsway]

Hi Brax, I tweaked my RM40's by sticking BH5 pieces behind the midwoofer and mega woofer, then removed the fiberglass and foam lined the unstuffed cabinets with mattress topper foam to give a clearer airway path to the passive. I caulked my neo box seams, lined them with foam and chose Acoustuff over lambswool in my own tests behind the Neos and I made careful Neo gaskets for a tight seal on them too. The result was greater impact and weight overall for a satisfying improvement worth the effort. My RM40's already had FST's, and I don't know what the spirals sound like, but my feeling is to stay with the spirals so your treble power can keep up with those 4 neos. I never felt the FST was keeping up with the Neos and actually removed the low pass to the Neos and let them go all the way and just let the FST fill in the air at the top. To me the FST is very delicate sounding for top clarity in the quiet moments, but sounds overwhelmed by the louder treble parts of music. Another radical thing I did later was to try all midwoofers and set aside the mega woofs, so I would have a symmetrical soundfield, rather than the higher soundstage of just a top midwoofer. Have fun!  JAY

[Brax]

I received the mid woofer drivers, they are VERY nice drivers can't wait to install them. I also picked up Early B's LRC he was selling. Although the center was damaged in shipping (the tweetwer is not working) I hooked it up while waiting for the FedEx claim to be resolved. Even in it's condition, this speaker rocks. It has changed my whole sound stage and I couldn't be more impressed. I can't give the LRC a fair review until it's repaired but at this point I can't see how anyone would pick another model or brand over the LRC. There's still work to be done, upgrade the 40's, have the LCR repaired, replace my pre-pro and get some RM2's for surround duty. The last will need to wait till the dust settles on money already spent or the market rises sharply, but I will not settle for anything less than a full VMPS system.

[John Casler]

I received the mid woofer drivers, they are VERY nice drivers can't wait to install them. I also picked up Early B's LRC he was selling. Although the center was damaged in shipping (the tweetwer is not working) I hooked it up while waiting for the FedEx claim to be resolved. Even in it's condition, this speaker rocks. It has changed my whole sound stage and I couldn't be more impressed. I can't give the LRC a fair review until it's repaired but at this point I can't see how anyone would pick another model or brand over the LRC. There's still work to be done, upgrade the 40's, have the LCR repaired, replace my pre-pro and get some RM2's for surround duty. The last will need to wait till the dust settles on money already spent or the market rises sharply, but I will not settle for anything less than a full VMPS system.

That's the spirit!!

The LRC is certainly a great Center, and much LARGER than many realize (but it is called LARGE RIBBON CENTER)

The bargain of the year is the LRCjr at $549!!

* Spiral Ribbon Tweeter
* Standard Neopanel Midrange Driver
* 6.5" poly/mica woofer 20oz magnet 4 layer VC
* Piano Black, Light Oak, Dark Oak, Cherry = Bud Baily Cabinet (limited to stock on hand)
* SR71 Cabinet Damping
* Fully equalized polyprop x-over
* Power Handling 200W
* 4 Ohms, 90 dB/1W/1m
* Front Ported for easy placement
* 10.5H x 32W x 13D

How can you beat that?

But I have a few VMPS'ers who are taking a pair of RM40's and laying one down (horizontally) for the CENTER, and then placing the other in the rear (6.1) to OUTSTANDING results.

[Brax]

Well, I finished all my planned upgrades on the 40's. The bass is improved and the midrange seems a bit clearer. I haven't had the chance to really play with them though and the new woofer should be given a little time to break-in. I actually also upgraded to a LRC that I bought from Early B (now fixed from the damage FedEx did). I listened to the Blu-ray of Heart live in Seattle and it sounded fantastic! Music on Blu-ray is the future, I can't wait for them to start offering Best of disks of my favorite artists. I also just picked up a Meridian 565 to replace my Pioneer Elite receiver running as a pro/pro. The Meridian (due in Wednesday) should make a huge difference with the ability to crossover the 40's properly and the use of better DACs.

Brian, you know this is all your fault! If I hadn't bought that first pair of RM40, I wouldn't be consumed with taking my system from mid-fi to Hi-fi. You really should put a warning label on your speakers, "WARNING: One taste and you will be completely addicted"

[LosGatosSTI]

Can I revive an old thread?