RS Microbe

[yamworld]

I have built a RS Microbe as

http://www.rjbaudio.com/Microbe/Reference_Series_Microbes_v3.pdf

when i was building it, my friend gave me a subwoofer, so I went for a sealed box instead a ported

Now, I have glued the mdf and when I tested it, the sound was very boxy and blurred. I am sure the speaker sounds worse than cheap computer speakers.

I want to know will there a big difference because I made a sealed cabinet. The only thing i didn't do is to round off the cabinet edge or drivers edge and apply damping materials.

thanks

[jerryanderson]

Re: RS Microbe

Have you installed any damping material in the cabs? IE: Acousta Stuff/Accoustic Foam or Poly Fill! This may help!

[yamworld]

Re: RS Microbe

I tried to apply 1" poly filter (uses in fish tank) at rear of the cabinet and not much help.

[djg]

Re: RS Microbe

Could you post a picture of your project?

[yamworld]

Re: RS Microbe

[djg]

Re: RS Microbe

Looks pretty good. I would put in the port, and do the roundover on the woofer backside, that looks pretty tight to me. Then you would have an exact duplicate of the original. Some sort of damping on the interior walls like acoustic foam or fiberglass too. I read the link you posted, and the builder did use somewhat unconventional material for interior damping.

And, not to insult you, check the crossover to make sure it is correct, and speaker polarity.

Also, woofers will change sound as they break in.

[donparsons]

Re: RS Microbe

If they sound that bad, something is definitely awry.

The Microbe is a very highly regarded design and should sound better than you would expect. I'd check the crossovers first. Also, if the enclosure is not glued together it can make a significant difference in sound.

[djg]

Re: RS Microbe

Here's some really cheap stuff I'm using on my latest project, acoustic fiberglass ceiling tiles.

[yamworld]

Re: RS Microbe

to make sure the crossover connection
i want to make sure in the RS28SA , the red dot is the positive
and there are six connections to the ground

as in the pdf

http://www.rjbaudio.com/Microbe/Reference_Series_Microbes_v3.pdf

[djg]

Re: RS Microbe

Red is universally positive.

[tomzarbo]

Re: RS Microbe

do the roundover on the woofer backside, that looks pretty tight to me.

I agree, there is not enough room for the woofer to breathe. The back side of the baffle needs to be scalloped for better airflow.

TomZ

[romanbednarek]

Re: RS Microbe

I haven't actually "heard" the RS version of the Microbe but I don't think that it should sound as bad as you are currently claiming.

I think that two issues that have been mentioned (scalloping the woofer hole to allow for more air flow and making sure the crossover is correct) are the most likely culprits.

I've used the original Microbe design with the Cerberus subwoofer design and sealed the ports without any issues, but I don't think I've ever listened to the Microbes alone (no sub) with the ports sealed. I always recommend that people put the ports in just for versatility because they are quite impressive as a ported speaker.

Now there is a slight chance that you have everything correct and are noticing the minor peak in the upper bass/lower midrange region that is inherent to the RS125 driver. This is something that I noticed about the Microbe designs that seems to give vocals a bit more warmth than usual but often compliments the sound in a musical way for that type of speaker (one of those cases where a slight stray from absolute neutrality can enhance the sound of a speaker).

I would first look into those two issues mentioned and then make another evaluation. I hope things work out for you in the end and expect that they will because I have yet to get a complaint from anybody who has built any of the Microbe variants (and I've lost count as to how many have been built overall).

[johnastockman]

Re: RS Microbe

to make sure the crossover connection
i want to make sure in the RS28SA , the red dot is the positive
and there are six connections to the ground

as in the pdf
http://www.rjbaudio.com/Microbe/Refe...icrobes_v3.pdf

I was going to make the same suggestion that Tom did about rounding-over the backside of the woofer hole...like this:



Some 1" thick quilt batting, or some of the other suggestions about damping material lining the interior walls. Also, the egg-crate type open-cell foam that PE sells lining the interior surfaces works also.

John A.

[romanbednarek]

Re: RS Microbe

I was going to make the same suggestion that Tom did about rounding-over the backside of the woofer hole...like this:



Some 1" thick quilt batting, or some of the other suggestions about damping material lining the interior walls. Also, the egg-crate type open-cell foam that PE sells lining the interior surfaces works also.

John A.

For all of the Microbes that I built (about 10 total) I used the 1/2" Sonic Barrier self-stick foam to line the cabinets. I was worried that if it was too thick that it might interfere with the air flow from the woofer in the relatively narrow cabinet.

[critofur]

Re: RS Microbe

I would be willing to mail you some superior "stuffing" material for free, as a kind of a public service. What I would send is Dow "Safe Touch Acoustic and Thermal Insulation" which has been tested by an actual speaker company to be almost as good as their proprietary material which I am not at liberty to disclose the details about.

It costs about $50 for a bundle of six sheets and what I would send you would be about 1/8 of one sheet (or however much I can stuff in a flat rate large Priority Mail envelope and it would cost me just a couple $ to ship. Interestingly, this material is only available in Columbus, OH as a "test market".

One of the reasons I would do this is because another user on here sent me a nice tube amplifier absolutely free - I simply need to replace one burnt out resistor and buy a new set of tubes for it.

Another option, if you don't wish to send me your address, would be this:

http://www.mcmelectronics.com/product/DISTRIBUTED-BY-MCM-LS00916-/LS00916

I would use spray contact adhesive to secure that to the top, bottom, side, and rear walls.

Also, definitely do as the others have suggested and give that woofer some breathing room by chamfering the inner edge of the cutout, except for small areas where the screws go in to the baffle to attach teh woofer.