BR-1 x-over modification

[panterra]

OK, Dennis, I got my BR-1 kit and the extra x-over components and it's a little rainy today. I got my soldering iron and 1/8th inch pegboard sans holes, so cover me, I'm goin' in!

[panterra]

> OK, Dennis, I got my BR-1 kit and the extra
> x-over components and it's a little rainy
> today. I got my soldering iron and 1/8th
> inch pegboard sans holes, so cover me, I'm
> goin' in!

First snag, the 0.4 Ohm resistor did not get ordered.

[panterra]

> First snag, the 0.4 Ohm resistor did not get
> ordered.
Having looked over the parts list on the Murphyblaster web page, the parts list failed to include the 0.4 ohm resistor that is on the woofer schematic shown above the parts list as R1012. Dennis, you might want to edit that page. I don't know if it needs to be removed from the schematic or added to the parts list. I'm kind of stuck here, now.

[panterra]

> Having looked over the parts list on the
> Murphyblaster web page, the parts list
> failed to include the 0.4 ohm resistor that
> is on the woofer schematic shown above the
> parts list as R1012. Dennis, you might want
> to edit that page. I don't know if it needs
> to be removed from the schematic or added to
> the parts list. I'm kind of stuck here, now.

I got to the tweeter schematic and the 0.25 Ohm (R2021) is missing from the parts list, as well.

[brianwalter]

> Having looked over the parts list on the
> Murphyblaster web page, the parts list
> failed to include the 0.4 ohm resistor that
> is on the woofer schematic shown above the
> parts list as R1012. Dennis, you might want
> to edit that page. I don't know if it needs
> to be removed from the schematic or added to
> the parts list. I'm kind of stuck here, now.
I'm not able to access Dennis' site at the moment, but I suspect those small value resistors aren't listed in the bill of materials because they don't exist. They are probably the DC resistance of the coils in series with them. Check to see if he didn't put a note to that on the schematic somewhere.

Brian Walter

[panterra]

> I'm not able to access Dennis' site at the
> moment, but I suspect those small value
> resistors aren't listed in the bill of
> materials because they don't exist. They are
> probably the DC resistance of the coils in
> series with them. Check to see if he didn't
> put a note to that on the schematic
> somewhere.

> Brian Walter

oh, you mean like this:

"Please note that any resistor shown in line with an inductor doesn't really exist if it's value is below 1.0 ohms. That's just lspCAD's confusing way of telling you the approximate dcr of the inductor itself. But any resistor above 1.0 ohms is very real--and very important." Uh nevermind. LOL

[panterra]

> OK, Dennis, I got my BR-1 kit and the extra
> x-over components and it's a little rainy
> today. I got my soldering iron and 1/8th
> inch pegboard sans holes, so cover me, I'm
> goin' in!

Just bench tested the first speaker, before soldinging and mounting everything. It worked fine, I just may be getting the hang of this. I followed the PE tutorial on building x-overs and translating them from the schematics. The tweeter terminals had one painted red. I assume that is for the positive lead. Neither of the woofers have any markings to distinguish + or -. Does it matter?

[dennismurphy]

Howdy I just flew in from Rome and it's midnight my time, so I'm only partially awake. The polarity of the woofer matters muchly. Are you sure there aren't any faint markings on it? But you have to connect the positive output from the board to the positive terminal of the woofer. Otherwise, you will end up with a big hole in the middle because the tweeter and woofer will be out of phase.

[brianwalter]

> Just bench tested the first speaker, before
> soldinging and mounting everything. It
> worked fine, I just may be getting the hang
> of this. I followed the PE tutorial on
> building x-overs and translating them from
> the schematics. The tweeter terminals had
> one painted red. I assume that is for the
> positive lead. Neither of the woofers have
> any markings to distinguish + or -. Does it
> matter?
Yes it does matter. Are you sure there isn't something stamped into the metal at one of the connection points? If not, connect a 1.5 volt battery across the woofer terminals and see whether the cone moves in or out. When connected such that the cone moves out, the plus terminal will be the one connected to the plus battery terminal. Hope this helps.

[panterra]

> Howdy I just flew in from Rome and it's
> midnight my time, so I'm only partially
> awake. The polarity of the woofer matters
> muchly. Are you sure there aren't any faint
> markings on it? But you have to connect the
> positive output from the board to the
> positive terminal of the woofer. Otherwise,
> you will end up with a big hole in the
> middle because the tweeter and woofer will
> be out of phase.

Well that is what I thought. There is nothing on the speaker that I can see. No stamps no + or _ no color difference. I guess I could pull apart my stock BR1 and see what is on that woofer, but i used that black cauld that was included. What a mess.

[panterra]

> Yes it does matter. Are you sure there isn't
> something stamped into the metal at one of
> the connection points? If not, connect a 1.5
> volt battery across the woofer terminals and
> see whether the cone moves in or out. When
> connected such that the cone moves out, the
> plus terminal will be the one connected to
> the plus battery terminal. Hope this helps.

I'll give that a try. I don't want to open up my other speakers.

[panterra]

> Yes it does matter. Are you sure there isn't
> something stamped into the metal at one of
> the connection points? If not, connect a 1.5
> volt battery across the woofer terminals and
> see whether the cone moves in or out. When
> connected such that the cone moves out, the
> plus terminal will be the one connected to
> the plus battery terminal. Hope this helps.

Hey that little trick worked great. And I didn't get shocked too bad, the positive is the one on the left when resting cone up. Thank you very much.

[Jeff B.]

> Well that is what I thought. There is
> nothing on the speaker that I can see. No
> stamps no + or _ no color difference. I
> guess I could pull apart my stock BR1 and
> see what is on that woofer, but i used that
> black cauld that was included. What a mess.

That is very odd. I have a hard time imagining that PE wouldn't make sure the terminals are marked in some way. I have a pair of 305 woofers here and just looked at them. There is a + and a - clearly marked on the small white fiberboard tab that the terminals are attached to on my speakers. Are you sure there is nothing stamped here on yours?

[panterra]

> That is very odd. I have a hard time
> imagining that PE wouldn't make sure the
> terminals are marked in some way. I have a
> pair of 305 woofers here and just looked at
> them. There is a + and a - clearly marked on
> the small white fiberboard tab that the
> terminals are attached to on my speakers.
> Are you sure there is nothing stamped here
> on yours?

I also had a hard time imagining that they wouldn't be marked. After I told my GF it wasn't marked she picked up the driver and asked if I meant the little + and - on the white fiberborad tab. $#^%#^@*%@!

[bking]

If one of the connecting tabs on the woofer is slightly wider than the other, that's probably the positive terminal.

[panterra]

> Just bench tested the first speaker, before
> soldinging and mounting everything. It
> worked fine, I just may be getting the hang
> of this. I followed the PE tutorial on
> building x-overs and translating them from
> the schematics. The tweeter terminals had
> one painted red. I assume that is for the
> positive lead. Neither of the woofers have
> any markings to distinguish + or -. Does it
> matter?

Last night I put together the other x-over and it tested fine in the speaker, so this morning I finished up placing them on their boards. Then started mounting with wire ties for the inductors and a dab of hot glue for the other components, and broke a lead of the 30-Ohm 10W resistor. No way to solder it, will have to replace it. I suspect that this is something I can get locally in Dallas. Isn't this where they invented the IC?

[blair]

I wondered about your screen name. RIP....

Anyway,

Where are you at in Dallas? There are several places to locate resistors. I can meet up with you and possibly give you a resistor if you want. If not, I can guide you to a location that will have them. I live in Allen. Where are you?

Blair

[panterra]

> I wondered about your screen name. RIP....

> Anyway,

> Where are you at in Dallas? There are
> several places to locate resistors. I can
> meet up with you and possibly give you a
> resistor if you want. If not, I can guide
> you to a location that will have them. I
> live in Allen. Where are you?

> Blair

PanTerra is my company's name, no relation to the band, although we used the same kinko's. I am in Richardson, Coit @ Campbell. i just called Radioshack and they didn't know what I was talking about other than resistor when I said I was looking for a 30 ohm 10 watt non-inductive Resistor. He referred me to All Tex in Carrollton.

[panterra]

> I wondered about your screen name. RIP....

> Anyway,

> Where are you at in Dallas? There are
> several places to locate resistors. I can
> meet up with you and possibly give you a
> resistor if you want. If not, I can guide
> you to a location that will have them. I
> live in Allen. Where are you?

> Blair

I just tried AllTex, and no luck in locating one there.

[blair]

Don't tinker with the Shack. I went to school right by you at UTD. Call Tanner Electronics

<A HREF="http://www.tannerelectronics.com/">http://www.tannerelectronics.com/</A>

or you can follow these directions. Take 635E west towards 35 Take 35 north towards denton, then exit Valwood. Take a left on Valwood under 35 and you will continue until you hit a steep train crossing no longer in service IIRC, but just over this steep crossing you will see a small strip mall type establishment to the right(take a right at first light) Directly on your left will be Tanner Electronics. They are a surplus electronics supply. You should be able to find the value above 5W there for about .20-1.00. If they do not have exactly what you are looking for, just get a 10 and a 20 to make 30 etc. or take the schematic and have Jim take a look at it. They are really good people and very reasonable for future projects.

I hope this helps, and email me if you want to swing by and hear my system or be invited to a DIY in the area.

Blair