Your Grounded...For not using protection. ;-)

Hello All,
In considering fused protection for my 2-Way project, I have some questions for you good folks.

1) Should I protect the entire system via the crossover Negative terminal going to a fast burn fuse?

I have considered taking the Negative from the woofer straight to the cabinet terminal and by-passing the Negative terminal on the board. This based on my unfounded assumptions that only the HF Driver needs protection. :idea: .
2) Is there any risk in doing this?

3) Will doing this alter the performance of the woofer and/or LP Filter?

I plan to provide protection for the tweeter and HP Filter. So curious if I should go ahead and connect the woofer negative into the board or not.
Thanks for you input.
 

infinia

Member
2005-05-15 9:51 am
SoCal
fuses are useful for powered equipment for safety (fire) <full stop>, almost never are they able to protect individual components, esp without interfering with normal operation. FWIW incandescent 12V light bulbs have been useful for protecting high powered tweeters. The amplifier should contain DC protect circuits that disconnect or crowbar the outputs, If not, consider adding one. still these things may only offer marginal speaker protection depending on the entire system specs.
edit BTW entire system = sources /amps + speakers
IDK why do newbees have a such a weird concept for fuses.
 
Last edited:

kevinkr

Administrator
Paid Member
Most likely tweeter protection IIRC.
I'm not a fan of fuses for speaker protection simply because as pointed out by the time they are effective against all forms of abuse they are audible all the time as well.

The best thing you can do for a tweeter is not to overdrive an under powered amplifier in a quest of head banging levels. Amp clipping is the bane of all tweeters as some percentage of the harmonics fall within the tweeter's passband and can be quite high amplitude.
 
Sounds like this is a feature from the seventies. :cool:
The original pair (ESS AMT5) had 2.5A Fast Burn Fuses.
I thought this was a good idea, but sounds like it is not needed.

I would agree with those who said they provide little protection, as I have experienced this little surprise.

Having said that, what about the original question regarding whether or not to ground the woofer negative to the binding post rather than the crossover board? Any recommendations? Suggestions?
 

krivium

Member
Paid Member
2009-10-13 2:43 am
I thought this was a good idea, but sounds like it is not needed.

Well it depends: if your speaker are in a potential situation to be used by a drunk man during a party with a clipping amplifier it can be a good idea (PTC if sized correctly are quite nice in this case), if only used by yourself with an amplifier correctly sized no need to protect them (as long as your are not the drunk one during the party :) ).
 
keep the wiring stock unless you show some schematics of your proposal. BTW using the word "ground" is unhelpful here.

What do you mean by "Stock"?
Nothing stock about DIY projects.
This may be a simple 2nd. order LR. Still haven't decided yet.

To simplify in Newbie terms...
Does it matter if I connect the little black wire with the (-) label coming from the woofer to the little black binding post? or should I provide a terminal on the crossover board (W-) and connect it there?

Does it matter?

Since it sounds like I will not incorporate a fuse, perhaps keep it consistent and run it through the board. Sometimes I think too much. :)
 

krivium

Member
Paid Member
2009-10-13 2:43 am
What do you mean by "Stock"?

Didn't you talked about an ESS model? I think this why stock was used.

Does it matter if I connect the little black wire with the (-) label coming from the woofer to the little black binding post? or should I provide a terminal on the crossover board (W-) and connect it there?

Does it matter?

Without a schem of your cross over it'll be hard to tell (even if you said LR 2pole it may be done several ways i suppose - i'm not an expert about passive crossover).

But from a practical point of view: soldering many wires to a binding post could be problematic if you need to take it out of the box for example, or if really tiny soldering multiple points to it can be an issue.

Does it matter from an electronic point of view? I would say no at first as it could look like a 'starground' schem. But more experienced builder could tell you better.

From what i've seen usually you have one (or more) board(s) and wire are ganged at this point and just a pair is used to the bindings post.
 
Last edited:
Well the AMT5 speakers are toast along with the receiver.
(Don't leave teenagers at home alone for the weekend). :(
And proof again fuses don't help.

I am however, repurposing the Heil AMT Power Ring HF drivers for this project.
And I was using the original crossover design as a guide.
But I've slowly realized a lot of the original design is dated and breaks many modern design rules.

Not sure what made me think to bypass the network for the woofer.
Seemed more streamline I guess.
I'd better stick with running it through the network.
Thanks for all the input.
 
Leaving the kids home unattended caused this blow up of a friends subwoofer amp. The driver's cone had actually caught fire briefly. I repaired the carnage and fitted a suitably rated polyswitch. I guess it's all about the risk factor.

Well the AMT5 speakers are toast along with the receiver.
(Don't leave teenagers at home alone for the weekend). :(
And proof again fuses don't help.

I am however, repurposing the Heil AMT Power Ring HF drivers for this project.
And I was using the original crossover design as a guide.
But I've slowly realized a lot of the original design is dated and breaks many modern design rules.

Not sure what made me think to bypass the network for the woofer.
Seemed more streamline I guess.
I'd better stick with running it through the network.
Thanks for all the input.
 

Attachments

  • DSCF0013.jpg
    DSCF0013.jpg
    524.6 KB · Views: 69

infinia

Member
2005-05-15 9:51 am
SoCal
This may be a simple 2nd. order LR. Still haven't decided yet.

To simplify in Newbie terms...
Does it matter if I connect the little black wire with the (-) label coming from the woofer to the little black binding post? or should I provide a terminal on the crossover board (W-) and connect it there?


If its 2nd order you need to wire the woofers plus AND minus to the crossover network absolutely, even a proper 1st order needs a zobel network on the board. You could add a 2nd wire on the negative direct to input depending on the schematic but I don't see any advantages gained. see "keep it stock" could also refer to store bought Xover PCBs yes> sometimes drawing connections out on a piece of paper helps
 
Regarding the Subwoofer amp - Yikes!!
"Dude, I think your dad's subwoofer is smoking, wait. what?" :cool:

I will provide a negative terminal for the woofer on the board.
I'm fab-ing my own PCB's and there is plenty of space for this.
I have included RC EQ for the woofer.

I have very detailed CAD drawings for the cabinet and PCB's.
I'm just lazy and don't do a lot of social media crap.
Need to create a Photo Bucket account somewhere for URL posting.

Visuals coming soon I promise.
After five years, still in the design process. :magnify:
 

infinia

Member
2005-05-15 9:51 am
SoCal
I'm fab-ing my own PCB's and there is plenty of space for this.

Ive yet to do this, i have purchased the Madisound blank PCBs and mostly just glue and solder parts on a 1/8 or 1/4 piece of wood. IMO fabbing PCB for low volume Xovers w/ simple and big parts just doesn't make sense.
RE CAD > often time drawing designed stuff by hand you can figure things out on your own. putting pretty drawing out in public takes more time than building the darn thingy
 
For me it's all about the journey and the experience.
I'm not sure I'm ready to call this a hobby.
More like an interest with a goal.

I'm trying the Presensitized single side PC Boards from Parts Express.
Looks pretty simple.
Will do mock-ups for testing with perforated fiber boards.
Final product will be on PCB for a professional look.

Trust me, I've gone through pages of grid paper. :)
CAD allows me to draw the components to scale.
Create the Trace paths, then reverse mirror the traces for PCB exposures.
CAD also makes modifications and revision work less time consuming.

You can download free CAD software from Dassault Systems...

Download DraftSight - Dassault Systèmes

DraftSight is an AutoCAD knock off program, which will take AutoCAD commands and convert them on the fly. So if you know AutoCAD you can run this easy.

Cheers!