First time DIY XO build, random questions

[ryanosaur]

When coming up with a crossover board layout, I find it useful to print a copy of this diagram and keep it nearby. Use alignment examples 1, 6, or 7. In your small 2-way, you might have a tough time finding 20 cm (8") as shown for #1. Do the best you can with the available space.

Align iron or steel core inductors with other inductors on the board the same as you would air core inductors. The iron or steel bar goes through the coiled wire hole in the same direction as you would look through the doughnut hole of an air core inductor.

You can find it here: http://www.troelsgravesen.dk/coils.htm
View attachment 39683

Still as good as it is from way back in post #5!

If you're really worried about that extra ¼" internal cabinet depth...

I'm not really worried, though Dennis suggested in the BR-1 cabinet, it will affect the lower end.

The cabinet I'm planning out right now will be .55 cu.ft instead of .52. Nothing more than that. Rough accounting for the new port and other internal losses to volume should bring it back to even. I'll get it modeled soon, I hope, for conformation.

 

[Swerd]

Still as good as it is from way back in post #5!

I completely forgot I posted that way back in January. It's been a long strange year.

 

[ryanosaur]

That’s putting it mildly.

 

[ryanosaur]

Funny thing @Swerd , I saw a Gravesen build that did not have the Inductors 10-20 cm apart...

I gotta ask everyone... I know you don't want inductors side by side, but what is the actual minimum distance you would place safely place them?

(Mind, as I got the originals out, there were 4 inductors on a 5x7" board... 20cm is roughly 8".)

Anyway... one other technical question...
Connecting all paths to ground: can these all combine at one point or do they need to connect in order as shown in the diagram?
(I've seen two different diagrams: the more common seems to trace the Neg lead back to the "Binding post, so any short in the XO connects at different points along that path. The less common diagram I have seen just shows those shorts terminating "to ground" with out the Neg lead drawn from Speaker to binding post.)
(It seems to me, that the connection back to ground can all occur at a single point. Please confirm, if so.)

Thanks!!!

 

[Swerd]

Funny thing @Swerd , I saw a Gravesen build that did not have the Inductors 10-20 cm apart...

I gotta ask everyone... I know you don't want inductors side by side, but what is the actual minimum distance you would place safely place them?

(Mind, as I got the originals out, there were 4 inductors on a 5x7" board... 20cm is roughly 8".)

If you go to http://www.troelsgravesen.dk/coils.htm you can see various arrangements of two coils where each coil is 0.56 mH. They're wired in series with each other resulting in 1.12 mH. Figures 1-3 show the inductances as the distance between the coils varies from 20 cm, to 10 cm, and as close as possible. You can see the minor differences. Sometimes, with limited space, I've had to vary from the ideal. It doesn't seem to make a major difference. Figure 4 shows a useful trick, if you need it.

Anyway... one other technical question...
Connecting all paths to ground: can these all combine at one point or do they need to connect in order as shown in the diagram?
(I've seen two different diagrams: the more common seems to trace the Neg lead back to the "Binding post, so any short in the XO connects at different points along that path. The less common diagram I have seen just shows those shorts terminating "to ground" with out the Neg lead drawn from Speaker to binding post.)
(It seems to me, that the connection back to ground can all occur at a single point. Please confirm, if so.)

The two different diagrams you described are simply different ways of drawing schematic diagrams. They both result in the same thing. Humans may care about the perceived differences, but electrons don't.

 

[ryanosaur]

Humans may care about the perceived differences, but electrons don't.

Just to clarify... connecting all grounds to a single common point is OK. (Forgive, Physics 1 in high school was a long time in the past. *blushes)

Re: the Inductors, I can't find the page, but it was a discussion about the TQWT and DTQWT designs... not any one in particular, and he had an air core and a c-coil in close proximity. Regardless, I do get it, and am strategizing my own way forward to keep as much space as possible between them and away from the magnetic fields of the drivers.
I tend to be very deliberate in my actions. The Lady says I over-engineer. I say quite simply that I aim to get it right once so I never have to redo it!

Thank you!

 

[Swerd]

Just to clarify... connecting all grounds to a single common point is OK. (Forgive, Physics 1 in high school was a long time in the past. *blushes)

I found two schematic diagrams to illustrate. The first one shows a 3-way speaker, where a single pair of binding posts are used. A number of different ground points share the same wire.

The next schematic three different looking paths to ground. They are drawn as separate paths, but they are no different than a drawing showing all three connected by one wire that goes to ground.

 

[ryanosaur]

Finally: progress!

It only took leaving my job... but I am assembling these XOs!
Pics soon.

 

[ryanosaur]

Two days of re-learning the ins and outs of basic soldering. FML. Ha! I'm pretty glad to be doing it. When I get the pics up, you'll be able to see the brutal progression... when I changed the tip on my iron... and hopefully nothing else.
Tweeter Circuits were finished yesterday; Woofer Circuits today. I also scraped out some glue from the original XO boards.
Tomorrow will be getting some hook-up wire and various connectors all attached. If all goes well, I'll have the Speakers fully assembled too! *fingerscrossed

I will have my Philharmonic AAs (with the original Dayton Tweeter) upgraded to the AA+ (Morel Tweet). ...Just as Dennis released his Quick Kit for these. *sadtrombone

Alas, I will have the satisfaction of having done this myself, though. A year in the making.

Whee!

 

[Alex2507]

It only took leaving my job

You quit your job to work on speakers? I'm concerned.

I tend to be very deliberate in my actions.

I thought I was too. And I am. But the battery polarity test said that was a lie.

A year in the making.

So it's the fast track for you.

TQWT and DTQWT design

The T and DT have me stumped. I understand QWT to be quarter wave transmission line?

My first foray with a soldering iron (since high school) was the Dayton BR-1s. That was the Golden Age of DIY when you could buy nice cabs from PE and Radio Shack was still open for soldering supplies.

 

[ryanosaur]

You quit your job to work on speakers? I'm concerned.



I thought I was too. And I am. But the battery polarity test said that was a lie.



So it's the fast track for you.



The T and DT have me stumped. I understand QWT to be quarter wave transmission line?

My first foray with a soldering iron (since high school) was the Dayton BR-1s. That was the Golden Age of DIY when you could buy nice cabs from PE and Radio Shack was still open for soldering supplies.

First, I left my job to leave my job. I’ve been in Service Industry well over 25 years... enough so that counting doesn’t even matter. In that time I have done just about everything except own/open my own restaurant: I have served (some), bartender, am a trained barista, done dishes, cooked every station in the kitchen from garde manger to pastry, trained and managed staff, been Executive Chef at a premier winery, and am a Private Chef (though I am not booking any engagements during the pandemic)..
COVID put an uncomfortable twist on life to be certain. In the end, it was the combination of the owners I worked for and the guests I served which left me no confidence in the safety of my staff and I. A few too many close calls with positive COVID tests among coworkers and a population of Covidiots thinking it’s ok to doff their masks to drink coffee in the cafe... just got to be more than I cared to keep handling.
In the end, there are several opportunities before me which I would otherwise not be able to pursue effectively as an employee, and so...
Like a bad habit, I dropped it. (And, being an employee... well IT IS a bad habit! )

Fast track, fo’ sure! The important thing is that I’m doing it.

Tapered Quarter Wave Tube... and Double. There is a link hidden in Troels website that shows his designs in this area. I only seem to stumble on it by accident when I look for other information.
...so maybe it doesn’t exist: it’s all just a dream. Go back to sleep.


Ah, the BR-1s. Cheers! To shared experiences!!!

 

[ryanosaur]

Day 3 offered slowdowns and setbacks. All minor.
Changed orientation of the Final Resistor in series to the Tweeter and lopped off about 1.5" of length from the Board. (Some was going to go, anyway, but this made it more compact.
I found a weak solder joint on one of the shunts to ground on the Tweeter Circuit. Repaired.
Played with all the connections to make certain nothing else broke loose.
Fixed some Solder Tag Strips to make common connections easier to manage (a trick I saw on Troels' site).
Got hook-up leads connected to each of the In and Out points.
Might be complicating things, but I am using Molex connectors to allow me an easier time of playing with this in the future. Those are each connected to the respective leads between Driver:Circuit and Terminal Cup:Circuit. (My goal is still to use this as my first cabinet build, which I've already measured for, and have rough panels cut and ready to go.)

Today will be: final preparation of the spots where the boards will fit, securing all components to the boards, and finishing the leads to the terminal cups and the drivers.

The only further complication I am aware of is that the Molex connectors came in a pack of 6... I need 8. I had originally bought them when I was still planning on using a single board for all the components. My acquaintance's insistence on me trying the 2mH and 100uF components changed that to two boards. *shrugs
All that will do is slow me down on final installation pending receipt of those connectors in two days. (Though given my track record, that might mean another 6 mos! )

 

[ryanosaur]

In various order:

The tweeter boards, drilled.

Woofer boards.

Tweeter Circuit, basic placement, all parallel components soldered.

Tweeter circuit, all components connected.

Same as above, but added the solder tag strip for the common ground.


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[ryanosaur]

Soldering under the influence. Good thing no one from OSHA came around! Though I would have offered them a delicious Monte Carlo if they wanted to join me!

Oh... woofer circuit rough layout on the board.

Both woofer circuits roughed in with solder tag strips. Mirrored because the BR1 cabinets have offset tweeters and the tweeter circuit will go on the sidewall opposite where the Tweeter is located. This gives an extra inch or so of space to separate the big woofer inductor and the first tweeter inductor.

Soldered woofer circuit.

And the other.


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[ryanosaur]

What it looked like originally.

And there you can see the lead popping out to the far left (under the inductor lead). This has been repaired.

And this is where I stand today.


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[ryanosaur]

The last pair of Molex connectors on one of the Tweeter Circuits.

Completed Tweeter Circuit, glued and strapped.


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[TLS Guy]

The last pair of Molex connectors on one of the Tweeter Circuits.

Completed Tweeter Circuit, glued and strapped.

That looks fine to me.
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[ryanosaur]

Completed Woofer Circuit, glued and strapped.

Here’s a closeup of one of the solder tag strips I mentioned earlier, bridged with some copper wire.


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[ryanosaur]

Had to do some Jigsaw Surgery today.

The old terminal cups were fouled with gobs of solder. I had a new pair of terminal cups I bought for the cabinet experiment, and so:

After carefully measuring, I traced the outline onto the cabinet, used 1/4” brad point bit to get the corners, and then set to work with the jigsaw, freehand.
Will have to repeat that process tomorrow.

Got creative with the wiring once I got the terminal cup fit. Was able to crimp two leads for each binding post onto the QDs. Split those off as + and - pairs to feed directly to each XO board with the matching Molex connectors.

In the end, I have fully completed the guts for one speaker:

Checked with the ol’ multimeter and got 6.5 ohms, so the whole system seems complete.

Tomorrow will catch the second speaker up as far as I can, pending delivery of that new set of Molex connections. Then, I will put this first speaker together!

Cheers!


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[ryanosaur]

Sad trombone moment.
Wa-wahhhh

In trying to get the tweeter board installed, one screw broke clean into the cabinet, and in the process, I cracked a resistor.

What’s one more delay?!

Time to go see about ordering that part, and clearly finding better screws!!!

I’ll be back next week to report: holding pattern until the parts arrive.

Cheers!


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