Fabulous Free Factory-Authorized Tweak!

zybar · « **Reply #20 on:** 13 May 2004, 05:38 pm »

Brian,

Thanks for the tip, much appreciated.

George

ekovalsky · « **Reply #21 on:** 13 May 2004, 11:46 pm »

Quote from: zybar

Eric,

I will wait to hear from you before I take apart anything.

Are you going to do both sides or leave the PR in place and do the single side?

George

I removed the PRs and applied glue to both sides. Avoided the spider and surround without any problem using a 1" brush.

Glue dries fast here in the desert, I'll be putting the drivers back in shortly and report back with listening impressions.

Per Big B no listening until six hours after glue application (about another hour).

Brian Cheney · « **Reply #22 on:** 14 May 2004, 12:07 am »

Give them at least six hours to harden fully.

ekovalsky · « **Reply #23 on:** 14 May 2004, 02:44 am »

Just fired the system up, after letting the glue cure for about 6.5 hours, and listened for about 30 minutes. I removed another lima-bean sized chunk of putty from each passive before I put the bases back on. The mass of the glue (applied to both sides of the paper cone) is more than the amount of extra putty I removed, so more putty may need to come off.

I do perceive more bass in the bottom two octaves, and what I hear sounds cleaner. I can feel my chair vibrating a bit more when the program has a lot of very low frequency sound, almost like I added a sub crossed over at 30hz to the system. Mid- and upper bass sound a bit cleaner too.

So far, I notice no detrimental effects from the glue application. I'm glad, because once it dries there is no way of taking it off without destroying the driver!

Thanks to Big B for an easy and very cheap tweak. Glue and paintbrush cost a total of $4

I'll report back after more experimentation with the mass loading. Since the mass of the driver has significantly changed with the dried glue on both sides, best thing to do may be to put it all back on and start from scratch ...

tkp · « **Reply #24 on:** 14 May 2004, 02:58 am »

Eric,

Did you get the carpenter elmer wood glue from Homedepot?

Thanks,
TKP

ekovalsky · « **Reply #25 on:** 14 May 2004, 04:20 am »

Actually I got it from Ace hardware, but I'm sure you could buy it at Home Depot or Lowe's, probably Walmart and Target also .

Brian Cheney · « **Reply #26 on:** 14 May 2004, 05:01 am »

Listen again after 24hrs as the cone material vitrifies. Amazing.

ctviggen · « **Reply #27 on:** 14 May 2004, 12:11 pm »

I always had the impression that the passive radiator was there simply to allow the woofers to move in and out. In this way, I thought that the PR acted like a port. I didn't realize that it affected the sound. Does it actually "radiate" sound as the name suggests? It would seem to me that it would produce sound opposite in phase to the woofers (when the woofer moves outward, the PR moves inward). Interesting. Well, this will be my first tweak after I receive my RM40s, although I'm going to wait quite a while to perform it, after I figure out placement and break in.

Xi-Trum · « **Reply #28 on:** 14 May 2004, 04:28 pm »

Brian, can the glue be applied to the 10" cones in the rm40? Or is it strictly for the passive radiator?

SCUBADON · « **Reply #29 on:** 14 May 2004, 05:17 pm »

OK, I applied the Elmer's to both sides of the PR on my RM40's last night. While I was at it, I replaced the puddy with factory shipped amount and set the pots back to factory original.

Listened this morning, sound great, about as good as they did when the pots and puddy were "set correctly". I am looking foward to seeing how good they will be once I have time tonight to do the adjustments again.

Thanks Brian for this "tweek"!

zybar · « **Reply #30 on:** 14 May 2004, 05:41 pm »

Well ,looks like I know what I will doing later on this evening or first thing in the morning...

George

Brian Cheney · « **Reply #31 on:** 14 May 2004, 09:25 pm »

The glue is for the paper-cone passive only. It won't stick to WCF which is plenty stiff to begin with.

ekovalsky · « **Reply #32 on:** 14 May 2004, 09:30 pm »

Quote from: ctviggen

I always had the impression that the passive radiator was there simply to allow the woofers to move in and out. In this way, I thought that the PR acted like a port. I didn't realize that it affected the sound. Does it actually "radiate" sound as the name suggests? It would seem to me that it would produce sound opposite in phase to the woofers (when the woofer moves outward, the PR moves inward). Interesting. Well, this will be my first tweak after I receive my RM40s, although I'm going to wait quite a while to perform it, after I figure out placement and break in.

Play something with a lot of low bass and put your ear close to the slot. You'll have your answer

JDoyle · « **Reply #33 on:** 14 May 2004, 11:37 pm »

Brian, Will you be coating the PR's on all future orders right at the factory?

JD

Brian Cheney · « **Reply #34 on:** 14 May 2004, 11:55 pm »

Yes, as of today.

brj · « **Reply #35 on:** 15 May 2004, 12:38 am »

Brian, did you ever get around to evaluating the lambs wool tweak? Is that tweak going to make it into your speakers as well?

Thanks!

ctviggen · « **Reply #36 on:** 15 May 2004, 01:47 am »

But if the woofer is moving outward and the PR inward to compensate, isn't the PR actually producing opposite phase and therefore detrimentally affecting the sound? (You'll have to excuse me -- I'm a patent attorney/engineer, and I think about how things work all the time. Incidentally, this is why I've gravitated to VMPS speakers -- they make sense to me. They seem like a great design, good enough so that I'm willing to buy them without ever hearing them.)

At least when Brian thinks something is important, he acts by immediately adding the tweak to the speaker.

Brian Cheney · « **Reply #37 on:** 15 May 2004, 02:31 am »

The PR is in inverted polarity to the rest of the bass range, true.

Fortunately the ear is relatively insensitive to polarity inversions below 80Hz, so we can get away with this (ports and vents also have output of inverted polarity).

The PR, not restricted by the requirements for motor and low moving mass of the active woofers, are excellent sources of first octave bass particularly when tunable. And as it turns out, when the cones are also very rigid.

tkp · « **Reply #38 on:** 15 May 2004, 03:06 am »

Brian,

How long should I wait after painting the PR with Elmer carpenter glue before putting it back in the RM40?

The instruction on the glue bottle says the drying time is roughly 30 minutes. I will not be playing the speaker until the 24th hour but it is pretty tough leaving the RM40s laying on the living room floor. My wife hates it and my kids are tempted to jump on the speakers.

Brian Cheney · « **Reply #39 on:** 15 May 2004, 03:11 am »

After the glue is dry enough to not run or drip you can install it in the cabinet Give the PR about 24 hours before play so the cone can vitrify.