Best technique to install crossover inside cabinet?

BobPM

Member
2005-08-15 8:29 pm
I am building the Zaph L18 design and after searching the forums, I have not seen a good discussion on how to install and secure the crossover inside the speaker cabinet.

Some guides, (partsexpress and speakerbuilder.net) suggest just using hot glue or silicone to secure the crossover board in the box. My concern, however, is that the better quality (read heavy) inductors that I am using will be too much weight for the glue if the cabinet is moved or turned on its side. Would it be better to screw the crossover to the base of the box?

I have also read in this forum that there is a benefit to isolating the crossover. Does this mean building a box within a box or just using isolating material (such as the glue) to absorb some of the internal resonance that might impact the performance of the crossover parts.

I would appreciate any suggestions or experiences of forum participants regarding the securing of their crossovers inside the cabinet. If a missed a thread on this topic in my search, please point me in the right direction.

Thanks for any suggestions.

BobPM
 

Ron E

Member
2002-06-27 10:41 pm
USA, MN
I use pegboard and tie-wrap large inductors. I hot glue everything else to the board. Velcro is nice way of mounting the crossover to the walls that is not subject to rattles, like loose screws or standoffs. I usually put the XO on the bottom of the cabinet.

Mounting outside the box is more of a convenience issue while a design is in the tweaking stage, IMO. While capacitors and inductors can be slightly microphonic, it is way down in the noise floor - microphonics are more of an issue with active electronics, where they are being amplified along with the signal.
 

BobPM

Member
2005-08-15 8:29 pm
I am using ties and hot glue to attach the inductors and capacitors to 1/4 inch plywood as a base.

Can you tell me if the velcro is strong enough to keep the crossover in place when the cabinet is moved? Also, if you wanted to mount the tweeter portion of the crossover higher in the cabinet, how would you secure it to the sides?

Thanks for your comment.

BobPM
 

Ron E

Member
2002-06-27 10:41 pm
USA, MN
I haven't used velcro for side wall mounting. No worries about the velcro coming loose if you use enough, but the glue could fail. I suppose for insurance you could staple the velcro. With Velcro you can pull the XO out without using tools in a cramped box.

If you shipped your speakers UPS and they dropped them off a conveyor, it might shake something loose, but it also might bend your driver frames or break off a magnet....

Planning on multiple transcontinental trips with speakers?
 

BobPM

Member
2005-08-15 8:29 pm
I appreciate the velcro suggestion, but after spending hundreds of dollars on speaker and crossover parts, i'm a little reluctant to just velcro the crossover. Is this just not an important part of speaker construction?

I expect that these may eventually end up in my son's dorm room and could be moved around fairly regularly.

Is there a better or more secure way to secure the crossover than velcro or glue?

Is there a downside to screwing the crossover board into the cabinet itself? If you do attach it with screws should you put any type of resonance absorbing material between the crossover and cabinet?

Thanks for taking the time to discuss.

BobPM
 

Ap

Member
2002-05-06 1:51 am
Sydney
Heres what I do.
Cut two identical boards - 1 for the xover & 1 to go in the box.
Drill holes in both for bolts, on the one that goes in the box mount the bolts. Screw/glue 1 in the box (with bolts & nuts).
Now you can just slip your xover board onto the installed one over the bolts, tighten down nuts - done!
Now you can easily remove your xover, tweak & re-mount.
I dont recommend hot glue - if you want to change components its a pain, I use cable-ties for all components.
 

soongsc

Member
2005-03-26 2:31 pm
Taiwan
BobPM said:
I appreciate the velcro suggestion, but after spending hundreds of dollars on speaker and crossover parts, i'm a little reluctant to just velcro the crossover. Is this just not an important part of speaker construction?

I expect that these may eventually end up in my son's dorm room and could be moved around fairly regularly.

Is there a better or more secure way to secure the crossover than velcro or glue?

Is there a downside to screwing the crossover board into the cabinet itself? If you do attach it with screws should you put any type of resonance absorbing material between the crossover and cabinet?

Thanks for taking the time to discuss.

BobPM

One way of doing it is to use piece of MDF about 12mm thick, counter bore a hole to bolt the inductor to the board, us a staple gun to staple straps to the board and tie the caps and resistors on it, then glue the board to the enclosure and ad a few nails with a nail gun if you like.
 

BobPM

Member
2005-08-15 8:29 pm
Ap:

On the board that you permanantly mount, how do you connect it to the cabinet?

Would it work to use both a small amount of glue and short screws to attach the base as solidly as possible to the cabinet to effectively make it part of the cabinet structure.

Also, is the glue for the countersunk bolts sufficient to keep them from spinning when you apply torque to the nut, or do you countersink with at least two flat edges so the bolt won't turn?

This technique seems like and elegant and very secure approach to creating solid removable crossover installation.

Thanks for the suggestion.
BobPM
 

soongsc

Member
2005-03-26 2:31 pm
Taiwan
BobPM said:
Ap:

On the board that you permanantly mount, how do you connect it to the cabinet?


Glue it as yu would clue you cabinet together, use a nails if you don't feel it's secure enough. You can use screws if you use solid wood or plywood.


BobPM said:

Would it work to use both a small amount of glue and short screws to attach the base as solidly as possible to the cabinet to effectively make it part of the cabinet structure.


If your cabinet is made of particle boards or MDF, it's not good to use screws. Otherwise the concept is good.

BobPM said:
Ap:


Also, is the glue for the countersunk bolts sufficient to keep them from spinning when you apply torque to the nut, or do you countersink with at least two flat edges so the bolt won't turn?


The countersink is used to sink "clawed" type bolts, I'll post a pic later.
 
Hi BobPM,

Any reason the x-over must go inside the enclosure? Would a separate enclosure for the x-over be an option? Unless the x-over is extremely simple in design, I'd prefer to have it outside the speaker enclosure.......much easier and always easy to access for tweeking or repair etc.

Cheers
 

Ap

Member
2002-05-06 1:51 am
Sydney
For the base board (mounted in the box) I just glue it to the inside.
I use two nuts on each bolt:
bolt/washer/base board/washer/nut/xover board/washer/ nut.
You can use split washers which will help lock nut to the base board.
The only reason why I dont use externals is tidyness.
I have been using monoblock amps, two subs with thier own amps + an HT setup with more power-amps - there are already enough boxes lying around.
Ideally external xovers are the way to go (for sound quality), but for me its not feasible.

FWIW:On my latest project I have switched to using Speakon connectors. You can get 4ways which are great for bi-wring.
I am mounting all xovers in my bass enclosures. Using two connectors, one input & one output to connect to mid-high box on top. I think its quite a neat solution.
 

Ap

Member
2002-05-06 1:51 am
Sydney
I dont use hot glue for the componets for one simple reason, if you want to remove a component to change it, the hot glue can damage it. I recently had this happen to a resistor - the 'sand' just poured out onto the floor!
I know they are cheap to replace, but now I have to make another trip/order to the store.
 
tade said:
very good point. Maybe dont use hot glue. You could use project circuit boards.
Most will agree hot glue could damage components upon disassembly.

Project circuit board is overkill, more expensive than other types of mounting materials.

Pegboard gives you convenient holes to run wire ties thru. While using pegboard I tend to spread out components taking up too much flat area.

I like 1/8" hardboard. Layout componets as tight as possible, drill a few holes where needed to mount components, strap down components with wire ties. DONE. The back surface of the hardboard is raised off the enclosure surface by the wire ties, one screw in the center of the board is all I use to secure to enclosure wall. I never hear anything from my installations.
 

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Can I add my weight to the external crossover idea? Put it in a non-metallic box (cheap plastic or wood would be fine), preferably close to the amp, held firm with cable ties. Then take separate cable runs to the drivers. The inside of a speaker cabinet is about the worst possible place for a crossover -far too many vibrations. Going the external route means you can optimise things more easily if you find, say, a caps value is off or one packs up on you. You could even fiddle with the cables -no fan of voodoo I, but selecting ones with optimised electrical characteristics won't hurt, though it won't make much of a difference either. A run of heavy-guage for the bass / mid drivers is usual (ring mains or 10AWG zip cord) and a cable with greater surface area for the tweeter (think on the lines of a good coax). I first did this with a pair of Acoustic Energy Aegis One standmounts a couple of years back (brilliant speaker for the money) and it made a worthwhile difference. I measured a fair bit less distortion afterward, which is always nice. There's even an article on doing this in this month's Hifi World Magazine.
Cheers
Scott