WD25A XL crossover question

[Cycleallday]

Afraid my electrical knowledge is minimal so I need help in determining if I have a problem or not. I have just bought some used 25A's with the XL tweeters and to aid transport I took out and boxed the drivers. When I came to refit them I needed to check the + / - of each speaker lead to connect them back properly. Also as I intend to biwire I removed the bridges from the tweeter/bass terminals on the outside of the crossover.

Now to the problem; putting a (continuity) meter on the leads I see the the outer terminals on the crossover connect to the base unit. However, the meter indicates both tweeter leads connect to the same (-) inner connector on the crossover; I get no reading from the inner (+) crossover terminal to any speaker lead. This seems wrong to me - is it?. Its the same on both boxes.

The speakers sounded fine when they were together and the tweeter/bass bridges in place. For now I have left the drive units out until I understand what is happening.

[Richard]

Hi,

I think we might struggle with terminology.

If you follow the crossover circuit, does it help if I point out that your meter uses DC to check continuity? You won't get a reading along connections made with a series capacitor in it. (The cap conducts AC so will connect for music.)

Rich

ps I should add you'll get a continuity reading through inductors and voice coils if the drivers are in circuit.

[Cycleallday]

Richard - thanks for lesson 1 (You won't get a reading along connections made with a series capacitor in it) - I am learning already now to the design v the actual board.

Just been checking my actual crossover with that shown in the design pages and it appears different to the one titled stage 3 XL crossover. Is there a stage 4 crossover design as I was told that is what was in there. Also things are making sense now I look at the design articles and read the words. But hey I am a typical man try first, if it does'nt look right ask and finally read the instructions if all else fails.

[petercom]

Production crossovers did take advantage of final tweaks included after the publication of the design articles, so Rev. 4 is correct.

[Cycleallday]

I have now carefully documented my crossover and have also been provided with a design which indeed matches it - well almost and hence a further post.

First is a simple question on reading values of components. On one resistor I see the figures

W21
1R0

which I understand as being a 1.0 ohm value as 1 is before the R and 0 after. I question this as the design I have quotes this as being 0.68ohm and I want to be sure I am reading it correctly. What does the W21 refer to - there appears to be resistors with the same top identifier but of different values below?

Second question is to help my learning. On the diagram attached there are a couple of instances of paired resisters and capacitors across the +/- connectors e.g. R1 and C2. On my crossover these are reversed e.g. the R1 is connected to the + line and C2 to the - line. Is this important as it is the case for every instance of this on my crossovers (the position of the resistor and capacitor are reversed when compared to the design). If it is important what would be the typical effect of this transposition?

What strated out as a simple connect up exercise is now turning into a good and enjoyable learning exercise.

Incidently the speakers are playing beautifully in the background; bi-amped with each drive unit connected to its own Meridian 5 series amp fronted by an Orbe/SME5 and the lovely AT-OC9ML/II cartridge reviewed in the last HiFi World.

Mel

[Richard]

Hi Mel,

First is a simple question on reading values of components. On one resistor I see the figures

W21
1R0

which I understand as being a 1.0 ohm value as 1 is before the R and 0 after. I question this as the design I have quotes this as being 0.68ohm and I want to be sure I am reading it correctly. What does the W21 refer to - there appears to be resistors with the same top identifier but of different values below?

Yes 1 ohm, R21 is the manufacturer's series identifier nothing to do with the value. I wouldn't expect the difference in value there to be very critical and wouldn't rush to change it. Perhaps email Peter to check.

Second question is to help my learning. On the diagram attached there are a couple of instances of paired resisters and capacitors across the +/- connectors e.g. R1 and C2. On my crossover these are reversed e.g. the R1 is connected to the + line and C2 to the - line. Is this important as it is the case for every instance of this on my crossovers (the position of the resistor and capacitor are reversed when compared to the design). If it is important what would be the typical effect of this transposition?

Not important in those connections.

What strated out as a simple connect up exercise is now turning into a good and enjoyable learning exercise.

The best way, have fun

[Greg.]

The crossover is pre assembled by WD before it gets to the customer.

[Cycleallday]

Thanks Greg,

Quite happy now - well at least I can listen to some nice sounds while I get on with making the larger cabinets and will understand the changes Peter is making to the crossovers when I come to buy the upgrade.

Mel