Noob needs help with Nat P Crossover

[james5]

Guys,

I'm obviously new to all of this, so I need your help. I recently finished the cabinets for my Nat P's, built the crossovers, put everything together, and plugged 'em in...and nothing happened! I think I may have wired the crossovers wrong. Could some of you wonderful people take a look at this picture and maybe tell me where I've gone astray? This is my first project and I know that my skills are nowhere near where you guys are...so help me out please! ;x(

Thanks--J

Here's a link to a pic of the crossover:

[ThomasW]

There was absolutely no sound from either speaker? That seems like something more than a simple crossover wiring error.

Your component layout and connections appear to be correct.





Due to the size of the picture it's impossible to know if the component values are correct or if you have cold solder joints.

[Dave Bullet]

Have you got a multi-meter? you should get DC readings across the resistors and inductors (of course with it all soldered, the connection could route other ways). I'd take a DC measurement across both legs (tweeter then woofer) parts of the circuit, then individual components to check for bad components and connections.

Have you only wired the speaker crossover so far? Also do a DC test across each driver (just raw terminal to terminal). You should read the published voice coil DC resistance.

David.

[StewLG]

Thomas, did you find the link to "large size"?

Here it is, if not:

[james5]

Have you got a multi-meter? you should get DC readings across the resistors and inductors (of course with it all soldered, the connection could route other ways). I'd take a DC measurement across both legs (tweeter then woofer) parts of the circuit, then individual components to check for bad components and connections.

Have you only wired the speaker crossover so far? Also do a DC test across each driver (just raw terminal to terminal). You should read the published voice coil DC resistance.

David.

I haven't got a multi-meter, but I could grab one at radio shack on the way home today.

I have an identical crossover wired to two RS180's and an RS28 in a cabinet. Perhaps I've wired those incorrectly? When wiring the woofers you run one wire with two branches going to the corresponding pos/neg terminals, correct?

I appreciate the help guys.

j

[james5]

There was absolutely no sound from either speaker? That seems like something more than a simple crossover wiring error.

Due to the size of the picture it's impossible to know if the component values are correct or if you have cold solder joints.

Thomas,

No sound at all and I've checked the source with the speakers I already have and had no problems.

What does a cold joint in solder look like? I've never soldered anything before so it's possible I screwed that up.

j

[james5]

grounding?

I just thought of something...am I supposed to have these grounded in any way? I don't have any of the speakers or crossover grounded.

[ThomasW]

Typically speakers aren't grounded like active electronics.

I can't see any obvious wiring errors.

A good solder joint is smooth and shiny like chrome. A cold solder joint is rough and dull in appearance.

Even if you have a few bad solder joints that alone shouldn't kill all the output from both speakers. So I don't know what's going on, but I have a hunch the main problem is elsewhere.

Do you have a friend/neighbor/co-worker who understands electronics? If so have them double check all the wiring in the speakers starting with the input terminals....

[ahaik]

If you have only one crossover assembled, make the other one very carefully using Thomas's image as a reference.
If both are assembled, try connecting one speaker at a time (maybe a cap got shorted causing the amp to shut itseff off).
those caps can be damadged if touched by the soldering iron.

[JonW]

One knuckle dragging, simpleton thing I do to test soldered connections is use a simple ohm meter. Put the leads on each side of a supposedly soldered joint. If there is no resistance, the joint is fine. If you don't get a reading, there is a problem.

[bluewizard]

How about a link to a schematic of the crossover, and/or a link to the source of your project information.

I'm looking at the crossover and it doesn't make sense. The (+) lead of the woofer is tied directly the the (+) input from the Amp. Also, there doesn't seem to be a common ground point.

Are these by some chance, SERIES crossovers?

EDITED:

Never mind, it is a Series Crossover and I did find a Schematic.

Steve/bluewizard

[ThomasW]

Are these by some chance, SERIES crossovers?

It's one of Jon's unique hybrid crossovers. And yes part of it is a series topology.



The NatP design fully documented is a large multiple page thread in the Missions Accomplished section

[james5]

Typically speakers aren't grounded like active electronics.

I can't see any obvious wiring errors.

A good solder joint is smooth and shiny like chrome. A cold solder joint is rough and dull in appearance.

Even if you have a few bad solder joints that alone shouldn't kill all the output from both speakers. So I don't know what's going on, but I have a hunch the main problem is elsewhere.

Do you have a friend/neighbor/co-worker who understands electronics? If so have them double check all the wiring in the speakers starting with the input terminals....

Most of my solder joints are on the shiny side. I did accidently melt a tiny bit of the plastic wire covering on a couple, but it didn't melt into the solder.

Unfortunately, I'm the only person (at least among the people I know) in Dallas that is trying this. Most of my friends think I'm nuts for trying this, but I love HT/Music. I'm sure there are people in Dallas that could help, but I'll probably have to ask around.

[bluewizard]

I saved both crossover images to my computer then loaded them in a file viewing program so I could switch between them easily. Following the reference image and comparing it to your image, all the connections look correct.

Assuming you haven't shorted something or that you don't have an open/cold solder connection.

Are you sure the reference photo you attach is for the FINAL crossover for the project. I'm looking through the thread, but it is 16 pages and that's a lot to sort through.

steve/bluewizard

[ThomasW]

Are you sure the reference photo you attach is for the FINAL crossover for the project. I'm looking through the thread, but it is 16 pages and that's a lot to sort through.

I'm sure it's the final crossover which is why I posted it.

The vast majority of the Missions Accomplished threads have all the data needed for the build condensed into the first couple of posts. The first posts are updated if/when there are changes in the design.

[james5]

Wow!

Ok, so I figured out the problem. When I put the binding posts in the bottom of the speaker I left some wire exposed and when I glued together the PVC for the port I must have dripped some right onto the exposed wire. I removed the binding posts and plugged in the bare wire and I've got sound! :T

My next question: When you play speakers outside of their enclosure are they supposed to sound "tinny" and thin? if not let me know so I can search for my next problem.

Thanks for the help guys!

j

[ThomasW]

When you play speakers outside of their enclosure are they supposed to sound "tinny" and thin?

Of course it's the box and baffles that create the full sound.

Glad you found the problem.. :T

[Dave Bullet]

When you play a driver in free air, the wave from the back of the cone wraps around to cancel the wave being created by the front of the cone. That explains why you need a baffle. An infinitely large baffle obviates the need to have a box. Because we can't have a speaker with an infinitely large baffle for practical reasons, we make the baffle smaller. A baffle / box contains or reduces the backwave cancellation - which means you get the fuller sound. A speaker in a box (whether vented or closed) is a monopole - because the driver is only meant to contribute to the sound from waves created from the front of the cone.

David.

[james5]

When you play a driver in free air, the wave from the back of the cone wraps around to cancel the wave being created by the front of the cone. That explains why you need a baffle. An infinitely large baffle obviates the need to have a box. Because we can't have a speaker with an infinitely large baffle for practical reasons, we make the baffle smaller. A baffle / box contains or reduces the backwave cancellation - which means you get the fuller sound. A speaker in a box (whether vented or closed) is a monopole - because the driver is only meant to contribute to the sound from waves created from the front of the cone.

David.

So I got the baffle back on the cabinet and it sounds better but still very "tinny". I built the enclosure much larger than the plans...the inside dimensions 11.5 wide x 13 deep x 36 tall. BoxyCAD puts it @ 2.1 CUFT. I haven't put any acoustistuff or anything in it yet. Do you guys recommend putting a good amount of that stuff in there to fill in the volume a little bit?

Also, I should have thought of this much earlier, but since the baffle is wider...do I need to adjust anything in the XO?

I appreciate the help fellas!

j

[Dennis H]

Also, I should have thought of this much earlier, but since the baffle is wider...do I need to adjust anything in the XO?

YIKES! Breaking out the beer and popcorn.

[ThomasW]

but since the baffle is wider...do I need to adjust anything in the XO?

Nope not a lot to do other than throw out the crossover you've built and have someone design a new crossover from scratch, OR build the box as it's shown in the NatP plans....your choice....because the crossover is designed specifically for the 9" wide baffle shown in the NatP thread...

[stangbat]

I built the enclosure much larger than the plans...the inside dimensions 11.5 wide x 13 deep x 36 tall. BoxyCAD puts it @ 2.1 CUFT. I haven't put any acoustistuff or anything in it yet. Do you guys recommend putting a good amount of that stuff in there to fill in the volume a little bit?

Also, I should have thought of this much earlier, but since the baffle is wider...do I need to adjust anything in the XO?

I appreciate the help fellas!

j

Okay, I'll try and refrain from freaking out. :B You should have been asking questions here way before this point. By my calculations, you more than tripled the enclosure volume (3.11 cuft vs. 1.0 cuft). Stuffing is only going to make matters worse. No wonder it sounds bad. Your enclosure is so oversized that you can't even put a shelf at some point to lower the volume down to what is required because the drivers will be in the way. You would need to put a shelf and a back in it to lower the internal volume down to what is needed (if you want to use the enclosures you built).

As for the baffle and the crossover, yes the extra width makes a difference. You'll probably have to live with it unless someone wants to take the time to redesign the crossover.

I'd suggest that you take apart what you have, cut everything down to size, and do it right. You can make the cabinets tall, just put a divider inside so that the internal volume that contains the drivers is 1 cuft.

[james5]

poo

I intend on building the Natalie P, but have a question regarding cabinet placement and baffle size. The exact external dimensions of my box are 10.5" (width) x 32" (height) x 8" (deep), which yields an internal volume of 1.03 cf when using 3/4" mdf. That said, I want to mount the cabinets on the wall next to my plasma tv (say 3-4" space between plasma and speaker cabinet edge), will my cabinet design cause any problems (say with BSC, driver placement, etc)? I'm not that all familiar with any simulation software so I would really appreciate your feedback before I order the xover components. (FYI the port will fire from the bottom of the cabinet). Any help would greatly be appreciated as I intend on ording parts ASAP. Thanks

No one responded negatively to this ^guys post in the Natalie P thread. That's why I thought that it didn't matter that much. I also saw several posts with people planning to build floor standing versions with no mention of modifying the crossover. I guess I should have asked before modifying someones perfectly good design.

[james5]

Okay, I'll try and refrain from freaking out. :B You should have been asking questions here way before this point. By my calculations, you more than tripled the enclosure volume (3.11 cuft vs. 1.0 cuft). Stuffing is only going to make matters worse. No wonder it sounds bad. Your enclosure is so oversized that you can't even put a shelf at some point to lower the volume down to what is required because the drivers will be in the way. You would need to put a shelf and a back in it to lower the internal volume down to what is needed (if you want to use the enclosures you built).

As for the baffle and the crossover, yes the extra width makes a difference. You'll probably have to live with it unless someone wants to take the time to redesign the crossover.

I'd suggest that you take apart what you have, cut everything down to size, and do it right. You can make the cabinets tall, just put a divider inside so that the internal volume that contains the drivers is 1 cuft.

Yeah, I'd say I should have maybe asked a couple of questions before now! :E Oh, well...I guess this is how you learn.

I can't cut my cabinets down because I did the whole "translam" thing to get a cool shape. In hindsight I wouldn't recommend trying it for your first project. 8O

[stangbat]

No one responded negatively to this ^guys post in the Natalie P thread. That's why I thought that it didn't matter that much. I also saw several posts with people planning to build floor standing versions with no mention of modifying the crossover. I guess I should have asked before modifying someones perfectly good design.

He kept the internal volume the same (1 cuft). How wide is your baffle (external dimensions)? 13 inches?

I can't cut my cabinets down because I did the whole "translam" thing to get a cool shape. In hindsight I wouldn't recommend trying it for your first project.

Then I'd suggest you make an internal shelf and false back to get your volume close to 1 cuft. You have enough money and time invested that you should at least do this if you want them to have a chance of them sounding somewhat like they should.

[james5]

He kept the internal volume the same (1 cuft). How wide is your baffle (external dimensions)? 13 inches?

Then I'd suggest you make an internal shelf and false back to get your volume close to 1 cuft. You have enough money and time invested that you should at least do this if you want them to have a chance of them sounding somewhat like they should.

The baffle is 11.5 wide externally...I messed up when I said 11.5 internally.

I have enough MDF left to go for the false shelf and back. Could I turn the bottom into some sort of bass bin enclosure? The baffle is wide enough to put something pretty serious in there. What are my options on that end?

[stangbat]

The baffle is 11.5 wide externally...I messed up when I said 11.5 internally.

I have enough MDF left to go for the false shelf and back. Could I turn the bottom into some sort of bass bin enclosure? The baffle is wide enough to put something pretty serious in there. What are my options on that end?

You are in better shape than I thought since you originally said internal dimensions. That is why I had 3.11 cuft for your enclosure volume. I now get 2.3 cuft.

I'm assuming that you used 3/4" material? So your internal dimensions are 10"w x 11.5" d x 34.5" h? If so, you may be able to get by with placing a shelf at the top and bottom of the enclosure to cut your volume down. I.e. no back necessary.

Someone else will have to comment on how big of a deal the extra 2.5" on the baffle width will be.

As for a bass bin, I wouldn't go messing with things anymore than you have. Use the bottom chamber to place the crossover.

[james5]

Could I go with one of these? http://www.partsexpress.com/pe/showd...number=295-368

With one of these"

http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=300-802

Do I need something like unibox to check the size of enclosure to see if I could make it work with the room I'll have left after I "block out" some of the volum of the enclosure for the Nat P?

[james5]

You are in better shape than I thought since you originally said internal dimensions. That is why I had 3.11 cuft for your enclosure volume. I now get 2.3 cuft.

I'm assuming that you used 3/4" material? So your internal dimensions are 10"w x 11.5" d x 34.5" h? If so, you may be able to get by with placing a shelf at the top and bottom of the enclosure to cut your volume down. I.e. no back necessary.

Someone else will have to comment on how big of a deal the extra 2.5" on the baffle width will be.

As for a bass bin, I wouldn't go messing with things anymore than you have. Use the bottom chamber to place the crossover.

Aww...but messing with things has gotten me where I am today.

I'll cut the volume down and report back. Maybe I'll even post some picks of these Fat Nats so you guys can see what not to do.

[stangbat]

I'm not sure I understand what you are asking, but I'd stick with fixing what you have as good as is possible. It won't be perfect, but it will be better than what you have now. Unless you want to start over completely, stick with what you have and fix it.

You can use unibox to check the size. The main thing is to see if you can get the shelves close enough together to lower the volume but also allow space for the drivers in between them.

Edit: We crossed paths with our replies.

[bluewizard]

I'm was curious too, because in the Nat-P thread, it does show both bookshelf MTM and several very nice Tower MTM's.

Quoting from the start of that thread -

For maximum authority in the bottom end, a small tower enclosure is recommended- 50 liters net for the two shielded RS180's, (p/n 295-364) with a 3" port tuned to 28 Hz (28 cm (11") long if not using a flared port kit); this will produce an F6 of about 29 Hz anechoic.

If space and size are a factor, then a slim bookshelf enclosure of ~ 30 liters can be used with a 2" port tuned to 32 Hz, which will result in an F6 of ~ 38 Hz, with some in room extension below that.

50 liters is 1.77 Cu.Ft.

30 liters is 1.06 Cu.Ft.

But, the project then goes on to create the project using what I think is a 1 Cu.Ft. ready-made cabinet from Part Express.

If this is true, then a 1.77 Cu.Ft. cabinet is correct if the port dimensions also follow the 50 liter model.

...with a 3" port tuned to 28 Hz (28 cm (11") long if not using a flared port kits..."

It would seems if James5 has the right port, it would seem he only needs to make a minor adjustment to his cabinet volume. Apparently, he can't do much about the width of the cabinet.

If I've read correctly we are currently at 2.1 Cu.Ft. and we need to drop down to 1.77 Cu.Ft.; a difference of 0.33 Cu.Ft.

Am I right, or is there something I have missed?

EDITED:

If you go to post number #280 (page 8 ) in the 'Natalie P' thread, you will see plans for a 47L tower. 9"w x 11"d x 42" h (o.d.).

I also notice some people saying they were building +60 Liter versions (+2.12 Cu.Ft.) and the only comments were that they tune the ports correctly for the cabinet size.

For what it's worth.

Steve/bluewizard

[james5]

I'm was curious too, because in the Nat-P thread, it does show both bookshelf MTM and several very nice Tower MTM's.

Quoting from the start of that thread -

For maximum authority in the bottom end, a small tower enclosure is recommended- 50 liters net for the two shielded RS180's, (p/n 295-364) with a 3" port tuned to 28 Hz (28 cm (11") long if not using a flared port kit); this will produce an F6 of about 29 Hz anechoic.

If space and size are a factor, then a slim bookshelf enclosure of ~ 30 liters can be used with a 2" port tuned to 32 Hz, which will result in an F6 of ~ 38 Hz, with some in room extension below that.

50 liters is 1.77 Cu.Ft.

30 liters is 1.06 Cu.Ft.

But, the project then goes on to create the project using what I think is a 1 Cu.Ft. ready-made cabinet from Part Express.

If this is true, then a 1.77 Cu.Ft. cabinet is correct if the port dimensions also follow the 50 liter model.

...with a 3" port tuned to 28 Hz (28 cm (11") long if not using a flared port kits..."

It would seems if James5 has the right port, it would seem he only needs to make a minor adjustment to his cabinet volume. Apparently, he can't do much about the width of the cabinet.

If I've read correctly we are currently at 2.1 Cu.Ft. and we need to drop down to 1.77 Cu.Ft.; a difference of 0.33 Cu.Ft.

Am I right, or is there something I have missed?

EDITED:

If you go to post number #280 (page 8 ) in the 'Natalie P' thread, you will see plans for a 47L tower. 9"w x 11"d x 42" h (o.d.).

I also notice some people saying they were building +60 Liter versions (+2.12 Cu.Ft.) and the only comments were that they tune the ports correctly for the cabinet size.

For what it's worth.

Steve/bluewizard

Man, I knew I had seen somewhere that guys were going larger with their cabinets. I tried searching the Nat P forum for a little while, but gave up and went to bed.

So really my question now is how do I make these sound less tinny? Do I put dampening material on the cabinet walls? Do I go with putting a partition in the cabinet to decrease the volume? What are your opinions?

[stangbat]

Thanks for finding that info, Steve.

James, you need to find out for sure if your cabinets are too big. No matter what, you will need to adjust the port length due to the change in cabinet size. Yes, you need to put damping material on the walls, but that alone will not take care of the oversized cabinet.

Based on the info Steve found, I think that the 1.77 cuft cabinet with a 3" port looks like a good bet. You'd probably only need one shelf to achieve that volume.

[james5]

Thanks for all the help guys...I'm going to make some changes and see what she sounds like.

I'll try to post some pics of what I do.

j

[---k---]

There are things you can and can't change with the box design. This question gets asked and answered repeatedly. If we miss it once or twice, it is because it has been asked way too many times. I've discussed briefly with Thomas writing an FAQ. But, my time is limited, and it seems that people don't read the FAQs when they are there.

As for your "tinny" sound. I think the box will do some funky things for you, but it won't destroy the sound. It will likely sound a little lean and have less low bass from the port, and it will probably sound a little forward with too much midrange and top end, and you might get a little mushy. But, "tinny" is not the way I would describe what I would expect. "Tinny" would be the word I would use to describe something that sounded like it was shorting out or just way wrong.

So, if the speakers sound okay, but a little mushy and bright it is likely the box. If it sounds just completely wrong, it is likely you still have a wiring problem somewhere.

There have been other people from Dallas post here recently. I highly recommend putting your location in your profile. If you can't find the problems, then maybe put out a general request for help.

[Dennis H]

James, is your box ported? I missed it if you said one way or the other.

[james5]

James, is your box ported? I missed it if you said one way or the other.

Yes, it has a 3" flared port @ 10.25" long.

[Dennis H]

Okay, double check your wiring to the drivers. For example, if one of the woofers was wired with the polarity reversed, the two woofers would cancel each other. There's got to be a wiring error somewhere -- no way it should sound tinny (which I take to mean no bass at all) in that enclosure. It won't be optimum until you get some stuffing in there but it shouldn't be that bad. Are you sure you found all the places where you slopped glue?

[stangbat]

Good thinking, Dennis. I kind of freaked out when the initial dimensions were given as inside dimensions, meaning an enclosure of >3 cuft and a baffle 13" wide. "Tinny" probably does mean something is mis-wired and the bass is getting canceled. Get that fixed and tune the enclosure properly and things will be much better.

[JonW]

James,

I agree with the others who have said that the box is important to be as designed. So if you can remake the cabinets, that would be best. But if you keep with your "fat Nat" one thing to minimize the damage might be to narrow the effective baffle width that you do have. For example, cut a 45 degree chamfer down both the left and right sides. If you can cut off 3/4" from each side, that would bring your effective baffle width down to around 10". That's a lot closer to the called-for 9" and it should sound closer to Jon's original design.

And just checking: You do have all the drivers the correct distance and orientation with respect to each other. Right? See the diagram Thomas posted.

Also reduce the volume like others said. And use nibox and/or WinISD to figure out the designed tuning so you can have that consistent with your new volume and port length.

[james5]

Ok, so I've "stuffed" fat natalie with a whole 12 oz bag of poly-fil and put 2 inch dampening material along the back of the cabinet. The sound is much much better, but the mid's are a still a bit muddy.

Do I need to take poly-fil out or add more poly-fil? Do I still need to reduce the cabinet volume even though I've put all this stuffing in?

[james5]

James,

I agree with the others who have said that the box is important to be as designed. So if you can remake the cabinets, that would be best. But if you keep with your "fat Nat" one thing to minimize the damage might be to narrow the effective baffle width that you do have. For example, cut a 45 degree chamfer down both the left and right sides. If you can cut off 3/4" from each side, that would bring your effective baffle width down to around 10". That's a lot closer to the called-for 9" and it should sound closer to Jon's original design.

And just checking: You do have all the drivers the correct distance and orientation with respect to each other. Right? See the diagram Thomas posted.

Also reduce the volume like others said. And use nibox and/or WinISD to figure out the designed tuning so you can have that consistent with your new volume and port length.

I think I'm going to to take your advice on the baffle. My baffle is only 3/4" thick so I could stand to double it to make it more rigid. I could laminate another "baffle" of the correct size over the existing one. Would that help?

The spacing of the drivers is identical to the diagram Thomas posted.

Thanks for the help!

[stangbat]

Ok, so I've "stuffed" fat natalie with a whole 12 oz bag of poly-fil and put 2 inch dampening material along the back of the cabinet. The sound is much much better, but the mid's are a still a bit muddy.

Do I need to take poly-fil out or add more poly-fil? Do I still need to reduce the cabinet volume even though I've put all this stuffing in?

I've said this many times before: stuffing the cabinet will not help with the increased volume. If anything, stuffing makes the cabinet volume act as if it is larger. Again, you need damping material inside, and lining the walls is sufficient. Stuffing is not going to cure anything.

Do the following and you'll be golden:
-Double check your connections
-Make sure the port length is correct for the cabinet volume you end up with
-Decrease the baffle size if possible as suggested
-Put damping material on the interior walls.

Edited suggestions per Dennis' comment below. Just make sure the port length is correct for whatever volume you end up with.

[bluewizard]

Don't know about the exact construction details of your cabinet, but would it be possible to add the additional front baffle to the inside to eat up some space, instead of adding a new one to the outside as you suggested?

Then, with the additional thickness, you could bevel the front edges so the width was correct. If I understand correctly, you need to take 1.1 inches off each side. Of course, if there are any nails or screws in the way, that shoots that idea down, unless you've got a first rate saw with carbide blades.

If you do add a new front on top of the old, would it be wise to round the edges of both the old and new front?

Pure speculation here.

[Dennis H]

His box volume is close enough to what Jon recommended that it doesn't need to be changed. If he wants to fiddle with the tuning, he can do it with the port length.