Built 1st of 3 Zaph ZDT3s...

[WillyD]

Hey all,

Don't know if this thread is kosher or not, but I figured I didn't know of a better place to start it.

Since I already had a 1ft^3 PE cabinet I decided to build the WMTW center first. Zaph had posted a rough center channel crossover, and I followed it exactly.

Now, it sounds like to me that dialog is a bit hollow when playing 5.1 tracks. Could this be due to not enough BSC? Phase wired incorrectly internally? Or maybe I am simply not used to the revealing RS52...

Otherwise, the center sounds fine.

http://www.zaphaudio.com/ZDT3.html

http://www.zaphaudio.com/ZDT3-options-3way-reducedBSC-FR.gif

[jkrutke]

Well, too little BSC usually comes through as "glare" or "forwardness". "Hollowness" might normally be attributed to insufficient absorption/damping material or a flipped polarity driver causing a null. Could you post an impedance curve to help verify the crossover by chance? If not, there's not much I can do to help with only subjective terms guiding me.

[WillyD]

Sadly I cannot. I don't have a WT3 or anything of the sort. When I have some free time later today I check the polarity for the drivers. I am pretty certain I have the tweet and mid wired out of phase as you had indicated, but oh well.

Thanks for posting John!

[WillyD]

Well I took the xover out and checked the wiring. The drivers were wired correctly. The problem has to be with how I assembled the components but even then I can't any glaring error(s).

I am close to just disassembling much of the xover and redoing the layout. It definitely sounds like there might be a big null in the midrange/lower-midrange.

[---k---]

I've had my polarity flipped on my last two builds. And just like you are describing, the vocals sounded a bit hollow. I would double / triple check that. Though, with the much higher crossover point of the ZDT3, not sure if this is a fair comparison....

You could also try posting a good photo of the crossover. I haven't built them, but it is a simple enough crossover that maybe someone here could spot the mistake. (Though, last time I told someone to do that, it was with a ModulaMT. I tried to review the photo and the diagram. wow, that is one confusing crossover to try and check with photos. not sure the guy got help...)

[jkrutke]

A polarity flip between the mid and tweeter would be much less noticeable. A polarity flip between the mid and woofer would cause a large null at 900 Hz. I'd ignore the markings and check polarity with a 1.5v battery.

Just to confirm: both the mid and tweeter should be out of phase with the woofers, but in phase with each other.

You might try describing how you have the system setup to see if there's any issues there. Maybe compare notes with Heatmiser who just completed the same center channel.

But mostly, I have to say it's hard to help folks without at least an impedance curve. I've got years of experience trying to troubleshoot speakers where someone though they heard a problem, but I'm sorry to say it's mostly been a waste of time even trying.

[WillyD]

I've had my polarity flipped on my last two builds. And just like you are describing, the vocals sounded a bit hollow. I would double / triple check that. Though, with the much higher crossover point of the ZDT3, not sure if this is a fair comparison....

Well, I noticed on some songs that the guitar parts are very quiet, that shouldn't be.

You could also try posting a good photo of the crossover. I haven't built them, but it is a simple enough crossover that maybe someone here could spot the mistake. (Though, last time I told someone to do that, it was with a ModulaMT. I tried to review the photo and the diagram. wow, that is one confusing crossover to try and check with photos. not sure the guy got help...)

Alrighty. I took some, don't laugh. ops:

Tweet/Part of mid board:



Part of mid/Woofer board:

I'd ignore the markings and check polarity with a 1.5v battery.

I just checked the xover with a 1.5v battery and everything looks right polarity wise.

Just to confirm: both the mid and tweeter should be out of phase with the woofers, but in phase with each other.

Gotcha. Thats how they checked out.

You might try describing how you have the system setup to see if there's any issues there. Maybe compare notes with Heatmiser who just completed the same center channel.

As the center in a 5.1 setup, using a Panasonic XR-55. I ended up moving it to L duty on a stand so I could more easily listen to it using music. I looked for Heastmiser's thread but couldn't find it. I'd like to speak with him for sure.

But mostly, I have to say it's hard to help folks without at least an impedance curve. I've got years of experience trying to troubleshoot speakers where someone though they heard a problem, but I'm sorry to say it's mostly been a waste of time even trying.

Absolutely. You've been more than helpful as it is. I didn't expect you to even post.

[Dennis H]

Will, I can't quite follow what's going on there. What are the two loose wires on the woofer board?

As an aside, I'd build 3 separate boards in the future, each with input connectors/wires that run all the way to the terminal cup on the back of the speaker. It makes troubleshooting much easier than daisy-chaining boards/signals.

[nate1r]

Those inductors are way to close, you are definitely going to hear that. My suggestion would be to reasemble the entire crossover putting the inductors on opposite sides of the board. If there is another problem you have a good chance of finding it when you reasemble the crossover.

[servicetech]

To make things simpler mark on the boards which each component should be "L1, C1" etc. It appears that you have a polarity reversal from the tweeter board to the mid/woofer board. If when you hooked up the battery to the speaker terminals the woofer moved out, then I must have missed a wire somewhere.

I've always preferred to put all the components on one board, but I've never built a complex crossover.

[---k---]

the inductors are fine:

[---k---]

This is the crossover, right?

Image not available

EDIT: I was looking at the wrong crossover.

When I built my crossover, I kept it simpler. I ran three red wires from the terminal and 3 white wires. One to each board. This way, the 3 boards were all separate. You just have a + in and a - in and a + out the the driver and a - out to the driver. Then, run a wire from the - in to the - out. Connect all your grounds to this wire. You can do this by cutting the wire in the middle with the strippers and just push about 1/4" to move the sheathing. The wire all your positives up. To keep the reverse polarity straight, tackle this last by just flipping the wires on the driver itself, rather than on the crossover. If you use crimp on terminals with the red and white booties, you can make this more obvious. Otherwise, if you try and do it at the board, I find it confusing.

[---k---]

I'm confused by the mid. I see you come in to R6, I see the two 16uF caps for C7 and C11, and I see the notch filter, but then there is only 1 inductor where there should be 2. I think you got 1/2 the mid on the tweeter board and 1/2 on the woofer board. this is just too confusing. Got no clue. But your tweeter looks right.

[Dennis H]

I've always preferred to put all the components on one board, but I've never built a complex crossover.

Yeah, it gets really complicated to keep everything straight (at least for me) when you get tons of components.

[ThomasW]

As the center in a 5.1 setup, using a Panasonic XR-55. I ended up moving it to L duty on a stand so I could more easily listen to it using music.

Are you saying when used as a main speaker it don't have the 'hollow sound' it did when used as a center?

[WillyD]

Are you saying when used as a main speaker it don't have the 'hollow sound' it did when used as a center?

No, it sounds the same whether it is used as a main or center.

Will, I can't quite follow what's going on there. What are the two loose wires on the woofer board?

Its hard to tell from the pic but they aren't loose. One is hooked up to the large 60uf cap and the other is for the resistor. I had left it out so I thought I could fit it in the way I did after the fact.

As an aside, I'd build 3 separate boards in the future, each with input connectors/wires that run all the way to the terminal cup on the back of the speaker. It makes troubleshooting much easier than daisy-chaining boards/signals.

You're absolutely right. I should have done that. When I was preparing to build it I thought of just making two boards that could fit through the bracing holes in the 1ft MTM cabinet. This being my first 3-way xover, I kind of forgot about the difficulty of using just two boards (I obviously did my Modulas this way).

I am going to redo the xover for 3 separate boards tonight.

Those inductors are way to close, you are definitely going to hear that. My suggestion would be to reasemble the entire crossover putting the inductors on opposite sides of the board. If there is another problem you have a good chance of finding it when you reasemble the crossover.

As Ryan pointed out, I tried to follow the inductor placement 'rules' here. Since I'll be moving to three boards now, I'll definitely try to improve the situation, but I know that even still, this problem wasn't cause by the inductors being a bit too close.

When I built my crossover, I kept it simpler. I ran three red wires from the terminal and 3 white wires. One to each board. This way, the 3 boards were all separate. You just have a + in and a - in and a + out the the driver and a - out to the driver. Then, run a wire from the - in to the - out. Connect all your grounds to this wire. You can do this by cutting the wire in the middle with the strippers and just push about 1/4" to move the sheathing. The wire all your positives up. To keep the reverse polarity straight, tackle this last by just flipping the wires on the driver itself, rather than on the crossover. If you use crimp on terminals with the red and white booties, you can make this more obvious. Otherwise, if you try and do it at the board, I find it confusing.

That sounds like a good idea for a noob like me. :T

Got no clue. But your tweeter looks right

:rofl: And it sounds right. Its the rest that doesn't.

[jkrutke]

Being a "neat freak", sometimes when I look at other people's crossovers, I just cringe. I like organization that's easy to follow. Solder connections that look clumpy have a higher probability of a poor connection, and large clumps mean high heat. Caps and resistors can be damaged from heating up large clumps of solder too close to the component. Once the damage is there, it's very difficult to troubleshoot.

I always mount mine on boards and use backside jumpers to keep things tidy. This arrangement also allows for longer component leads, which keeps the hot solder further away from sensitive components.

Here's a set of SR71 crossovers as an example of how I typically do it. (I don't have a picture of a set of ZDT3 crossover boards unfortunately) If the crossover is complicated enough, it's good advice to do separate boards.

[HeatMiser]

I looked for Heastmiser's thread but couldn't find it. I'd like to speak with him for sure.

Hi. Thread here, but I honestly doubt there's any pertinent info in it. My crossover pics are worse quality than yours, and I chose to place the woofer and tweeter crossovers on a single board so the layout is almost as inscrutable too 8O My layout choices did give me more space between inductors than yours, but it seems we both used the coil alignment suggested by Troels' chart posted above, so I doubt that's the problem.

I did find my implementation of this speaker to be quite sensitive to over-stuffing, but I don't know as I'd call the overstuffed attempt "hollow"; more, umm, stuffy and lifeless. And mine's crammed into a .75 cu ft box so if not apples and oranges, at least red apples and green apples.

If I think of anything or see something odd in your crossover pics that isn't already mentioned I'll be sure and speak up.

[WillyD]

Being a "neat freak", sometimes when I look at other people's crossovers, I just cringe. I like organization that's easy to follow. Solder connections that look clumpy have a higher probability of a poor connection, and large clumps mean high heat. Caps and resistors can be damaged from heating up large clumps of solder too close to the component. Once the damage is there, it's very difficult to troubleshoot.

I knew you would cringe upon seeing mine. I took care not to damage any of the components, and some look clumpy because of the way I wrapped a wire around the component leads. At any rate, I'll redo them. They aren't up to par...aesthetically and aurally.

You'd be happy to know that my dad thought the baffles you built were machine made.

[WillyD]

I won't bother posting the pics of the rebuilt crossover. Needless to say, the speaker sounds dead on now! Even before the dialog started I knew it was significantly better. I need to hit the sack now, but tommorow I will finally put it all together.

I followed your recommendation to the t Ryan, thanks.

[jkrutke]

You'd be happy to know that my dad thought the baffles you built were machine made.

Now you're appealing to my obsessive / compulsive side. :B Too bad I can't do veneer nearly as well as cutting baffles. Time to go into machine mode, I'm cutting a new set of ZDT3 baffles today and redoing the design with the PE ND20. I guess the Aura NT1 can be considered a reward for the early adopters.

I won't bother posting the pics of the rebuilt crossover. Needless to say, the speaker sounds dead on now! Even before the dialog started I knew it was significantly better. I need to hit the sack now, but tommorow I will finally put it all together.

That's good news, I thought maybe a component was damaged. Cap behavior after being fried isn't very consistent. Some get "crackly" while some just change to smaller values. Let's have a picture of the center when you get it done.

[---k---]

I won't bother posting the pics of the rebuilt crossover. Needless to say, the speaker sounds dead on now! Even before the dialog started I knew it was significantly better. I need to hit the sack now, but tommorow I will finally put it all together.

I followed your recommendation to the t Ryan, thanks.

:T

And, I can't take credit for the suggestions I gave you. I didn't have a clue what I was doing when it came to assembling crossovers, so I spent a lot of time staring at the pictures JonMarsh and a few others have posted. It took a while to really understand what they were doing, but once I figured it out, it was like a lightbulb went off.

I just wish I could hear it.

[WillyD]

Now you're appealing to my obsessive / compulsive side. :B Too bad I can't do veneer nearly as well as cutting baffles. Time to go into machine mode, I'm cutting a new set of ZDT3 baffles today and redoing the design with the PE ND20. I guess the Aura NT1 can be considered a reward for the early adopters.

Hypothetically speaking, should something happen to my NT1s in the future, could I redo the tweeter portion of the xover and drop in the ND20?

That's good news, I thought maybe a component was damaged. Cap behavior after being fried isn't very consistent. Some get "crackly" while some just change to smaller values. Let's have a picture of the center when you get it done.

How easy is it to fry one? I am fairly positive I haven't done any damage.

My baffle doesn't look as nice as yours typically do, but I think it looks quite alright (except I didn't align the RS52 screws in any specific way so they are kind of off center...).

BTW, you'll love this setup: :twisted:

[dawaro]

I'm cutting a new set of ZDT3 baffles today and redoing the design with the PE ND20.

Could this be the future PE Flyer project?

[jkrutke]

Could this be the future PE Flyer project?

Possibly. In that case, all drivers would be available from PE so it would make more sense as a flyer project.

Hypothetically speaking, should something happen to my NT1s in the future, could I redo the tweeter portion of the xover and drop in the ND20?

I can't guarantee it at this point, but my goal is to have the mid and woofer filters the same as the original design and only change the tweeter. After all, it's the same tweeter frame, same spacing, same acoustic center offset and the ND20 is also capable of working down to the same Fc. All I really have to do is massage the response curve into my target.

[WillyD]

I can't guarantee it at this point, but my goal is to have the mid and woofer filters the same as the original design and only change the tweeter. After all, it's the same tweeter frame, same spacing, same acoustic center offset and the ND20 is also capable of working down to the same Fc. All I really have to do is massage the response curve into my target.

Thats exactly what I had in mind. It would be quite nice to have that capability. Should the NT1s never return in their current (or should I say past) form, if one of mine was damaged, I'd be kind of screwed.

[Operandi]

Thats exactly what I had in mind. It would be quite nice to have that capability. Should the NT1s never return in their current (or should I say past) form, if one of mine was damaged, I'd be kind of screwed.

I'm sure they'll come back. I think the question is more about the long term consistency of their availability.

I would defiantly pickup some spares when they come back in stock. Probably a good idea with any Ti based driver.

[WillyD]

I'm sure they'll come back. I think the question is more about the long term consistency of their availability.

I would defiantly pickup some spares when they come back in stock. Probably a good idea with any Ti based driver.

If/when they come back, I will. For now, i'll just keep being uber-careful with them.

I was going to post some impressions of the center last night but my browser closed before I posted them.

I listened to a classical DVD I have, Gala Concert from St. Petersburg. It has DD5.1 as well as DTS. The center is utilized well with violin/cello solos and Opera parts. The first violin solo sounded so clear. I could hear every breath the violinist took. Also, each page turn by the conductor was there. Really nice.

I also watched the 4th installment of the great John Adams mini-series and the dialog came across wonderfully. Zero complaints. I actually forgot I was using a center and just concentrated on the show. 8)

[Quwiksilver]

Great minds think alike Willy! That PE 1.0 f^3 cabinet seems just right with the correct baffle height and a suitable volume. I'll be running some box simulations on my own, but are you running yours sealed?

Also, do you think Zaph would still recommend the reduced baffle step version for a stand mounted center channel (under a projection screen)? The flatter midbass response is appealing, although it would seem that the horizontal power response would be odd with one woofer being the .5 in a W-MT-W arrangement.

Zaph, if you're out there, did you ever get around to measuring the Aura or Dayton rear-mount tweeters with grill fabric stretched over the front prior to press fitting? This would seem to be a convenient way to make a nice finger shield assuming it doesn't screw up the frequency response.

Scott

[WillyD]

I'll be running some box simulations on my own, but are you running yours sealed?

Indeed. I didn't think I should bother with ports for it since it'll always be crossed over at 80Hz (or at the lowest, 60Hz). And 1ft^3 minus the xover/drivers isn't the ideal volume for porting twin rs180s.

Also, do you think Zaph would still recommend the reduced baffle step version for a stand mounted center channel (under a projection screen)?

How far from the wall would it be? I think it would be neat if there were a couple of tweaks to slightly increase BSC.

[stangbat]

Willy, when you get your LR speakers done, I'd like your impressions on the high end when listening to music. Highs (5 kHz and above) seem very pronounced, to the point of being way too much. For example, the snare hits on Dire Strait's Money for Nothing are downright piercing at moderate volume.

I've moved my speakers around, and even relocated them to a different part of my basement when trying to figure this out. I've tested with my sound meter and the meter seems to back up what I'm hearing. I know that my room is contributing to the problem, but things seem way to bright even when taking the room into consideration.

I ordered a 2 ohm resistor to pad the tweeter a little more, but it isn't here yet. And I'm honestly wondering if it will be enough. Plus this is my first "official" build of a good quality loudspeaker and I'm trying to figure out how these are "supposed" to sound.

Have you noticed anything regarding the treble with your center channel since the tweeter runs full blast?

[WillyD]

Willy, when you get your LR speakers done, I'd like your impressions on the high end when listening to music.

I will let you know.

Highs (5 kHz and above) seem very pronounced, to the point of being way too much. For example, the snare hits on Dire Strait's Money for Nothing are downright piercing at moderate volume.

Thats a good clean recording, yes? I'd think it should sound great on these. Which speakers did you have prior?

I know that my room is contributing to the problem, but things seem way to bright even when taking the room into consideration.

My room is quite 'live' or bright i think, only because I haven't done any treatments.

I ordered a 2 ohm resistor to pad the tweeter a little more, but it isn't here yet. And I'm honestly wondering if it will be enough. Plus this is my first "official" build of a good quality loudspeaker and I'm trying to figure out how these are "supposed" to sound.

I ordered a 1ohm resistor to possibly pad the tweeter on my center, but I didn't install it and its necessity remains to be seen. I wouldn't be puzzled if you found the sound harsh on a rough or bad recording because this speaker is definitely revealing.

Have you noticed anything regarding the treble with your center channel since the tweeter runs full blast?

Maybe, maybe. I've noticed that with not-so-good tracks, it can be harsh, but so can my Modulas in that instance. I am going to get my mains built to-spec first and properly setup so I can judge with the entire front 3. So far, just testing with DPLII music setting, I don't notice any unusual harshness.

[stangbat]

I may be getting things under control. Tonight I messed around with some room treatments and it seemed to improve quite a bit. I know my room needs work, but evidently it needs more than I thought. I think the speakers I had before were not good enough to reveal the shortcomings of my room and I'm now noticing it.

Tomorrow I hope to get a chance to take some measurements with the sound meter to back up what I'm hearing. So in hindsight, my previous post may have been hasty, but I've been battling this brightness for about a week and I was looking for help. As I mentioned earlier, these speakers are much better than any I have owned before, so it is going to take a little experimenting and learning to figure out what is the best location for them and what is the best way to set up my room.

[JAS]

Being a "neat freak", sometimes when I look at other people's crossovers, I just cringe. I like organization that's easy to follow. Solder connections that look clumpy have a higher probability of a poor connection, and large clumps mean high heat. Caps and resistors can be damaged from heating up large clumps of solder too close to the component. Once the damage is there, it's very difficult to troubleshoot.

I always mount mine on boards and use backside jumpers to keep things tidy. This arrangement also allows for longer component leads, which keeps the hot solder further away from sensitive components.

Here's a set of SR71 crossovers as an example of how I typically do it. (I don't have a picture of a set of ZDT3 crossover boards unfortunately) If the crossover is complicated enough, it's good advice to do separate boards.

Looks like the boards are laying flat on the table. How did you do the back side to keep the connections recessed and can you show us a pic of it?

[Finleyville]

Looks like the boards are laying flat on the table. How did you do the back side to keep the connections recessed and can you show us a pic of it?

X2 please... :B

[jkrutke]

Looks like the boards are laying flat on the table. How did you do the back side to keep the connections recessed and can you show us a pic of it?

Hmm, no pictures, sorry. But my component leads typically stick past the back by about 1/4", and then I use braided bare copper jumper wire. When I mount in the cabinet, I will usually use a couple of small wood spacers, screwed into the crossover board for removal, and glued onto a cabinet wall. Here's a layout I did for the ZRT system which shows a board mounted in place and you can see the spacers screwed in.