Bracing, Damping, Acoustic foam for Monitor series (10, 7, 5, etc)?

spenrock

First time post, although I have been following you very knowledgable posts for some time.

I am about to start upgrading the crossovers in a pair of Monitor 5jr I recently picked up. While I have them opened up, I thought I might either brace and/or damp the cabinets since they seem relatively thin. I think I read some discussion about this some time ago, but I can't find the thread. My questions are:

Does bracing help improve the sound of 5jrs (and Monitor 10s that I plan to do later)?
How about damping with Dynamat or something similar on the cabinet walls?
Finally, what about changing the white, cheap looking fill to something else?

Any advice you can provide would be appreciated, or if this has been addressed, pointing me to the discussion would help to. Thanks and cheers!

F1nut

Do not put Dynamat on the cabinet walls and leave the not cheap poly fill where it is. What you can add is Blackhole 5 to the back wall directly behind the mid-driver(s). Use something like a 4" wide by 6" long strip behind each driver.

spenrock

Ha, ha. "leave the not cheap poly where it is." I stand corrected, will do. Wow, and Blackhole 5 is not cheap. From your comment I assume it is worth it? I guess I will have plenty left to do the Monitor 10s. Thanks for the advice, F1nut, I plan to put it to good use.

westmassguy

You can also use Sonic Barrier: http://www.parts-express.com/sonic-barrier-1-1-4-3-layer-acoustic-sound-damping-material-with-psa-18-x-24--260-535

xschop

How does one sonic barrier the 5Jr where the crossover network sets directly behind the midwoofers?
P.S. I left the not-cheap poly where I found it in the upper cabinet.

westmassguy

xschop wrote: »

How does one sonic barrier the 5Jr where the crossover network sets directly behind the midwoofers?
P.S. I left the not-cheap poly where I found it in the upper cabinet.

Carefully

xschop

I looked around and only saw where someone stuffed some Monitor 4's with fiberglass.

westmassguy

No fiberglass, just the Dacron. Keep what's in there originally. You can cut a couple sections of BH5 or Sonic Barrier 4" X 4", and put one above and below the crossover.
That should clear up the mids that are bouncing around, without over damping the enclosure.

xschop

Thank you WMG. Sonically, would it make much more difference if the X-over was recessed where a 4" x 12" sheet of Sonic barrier was placed on the back wall?

RandyCroissant

I used sonic barrier in my 2b build and noticed a big difference in the mids. I used 3- 2" wide strips with a 1" gap cut to fit behind each MW. I will warn you If you use to much you will diminish the bass

westmassguy

xschop wrote: »

Thank you WMG. Sonically, would it make much more difference if the X-over was recessed where a 4" x 12" sheet of Sonic barrier was placed on the back wall?

Not sure what you mean by recessed, you mean cut a round hole in the Sonic Barrier where the crossover is? If so, you're creating more work for yourself, just put the two pieces in there.

Agree with Randy, too much and you suck the life out of the music.

xschop

I have the tech drawing at shop, essentially an adapter that sandwiches between X-over and cabinet effectively pulling the X-over out and creating more cab space.

xschop

I ordered some of the Sonic Barrier to play with. I'll go with WMG's suggestion of two ea. 4x4" in my shop 5jrs. Looks like I'll have some material left over for my next home office set too.

akajimmy

This interests me greatly. I have a pair of 5jrs that are going to get some new veneer and that Sonic Barrier might be the way to go. Should I remove that not cheap polyfill if I add the Sonic Barrier? Should I still Dynamat the midwoofer basket too?

spenrock

So, if I understand the experienced heads here, to summarize:
1. Bracing not required. (Stiffer cabinet does not help in this case?)
2. Different poly fill not required; original not cheap stuff does the job.
3. Blackhole 5 (or cheaper option Sonic Barrier) in 4" x 6" strip opposite the midwoofer helps and recommended.
4. Damping (Dynamat) the midwoofer basket should help.

If I got it wrong, please correct me. I plan to upgrade the caps and resistors (likely Sonicraft & Mills), and add a little Blackhole5 or Sonic Barrier. If I'm suitably impressed by the sound, I might veneer the cabinets.

Thanks again guys.

RandyCroissant

All of the upgrade items you list will improve the speakers themselves. However you should consider the whole package from source, to amplifier, cables etc. In my rig I had a 15 amp daisy chained outlet feeding my HT that really messed with my amp.