Zaph ZRT build questions

[djn04]

I've posted this on another forum but thought i would post here as well since John is known to post on this forum.

I've built the cabinets with the exception of the baffles and the kit from Madisound will be here tomorrow.

Some pics of the cabs.











One of my questions is to comply with WAF restrictions I think I need to place the port on the back. I will be able to place the speakers about a foot from the wall. Will this setup work? My other option is to paint the baffle and mount the port on the front and "blend" it into the baffle as Lunchboxmoney did in his SR71 build.

If I place it on the back should it be at the same height as the design calls for?

Any comments or suggestions are much appreciated. Thanks

[lunchmoney]

lunchboxmoney???

One downside to blending and painting the port as I did is that it's virtually impossible to get the paint all the way into the port... you'll still see some of the black plastic port on the inside, or maybe some primer.... not a big deal, but not sure I'd want that on the front of the speaker... you can't see it in the picture below, but if it were a dead-on picture looking directly into the port you definitely could...

And yet on the other hand I still might like it better than NOT painting the port, because I personally didn't like the look of cheap plastic on an otherwise nice finish.

Also, it was a bit of work... had to mill the recess of course, and it took some work to blend the seam such that it disappeared... I think the end results were worth it though.

[djn04]

lunchboxmoney???

One downside to blending and painting the port as I did is that it's virtually impossible to get the paint all the way into the port... you'll still see some of the black plastic port on the inside, or maybe some primer.... not a big deal, but not sure I'd want that on the front of the speaker... you can't see it in the picture below, but if it were a dead-on picture looking directly into the port you definitely could...

And yet on the other hand I still might like it better than NOT painting the port, because I personally didn't like the look of cheap plastic on an otherwise nice finish.

Whoops. Don't know why I put the box part in there. You posts have really helped me with the cabinet construction. I hope mine come out as nice as yours.

I was wondering about that. When you painted it did you plug the end of the port with anything or just let the paint enter the cabinet. If I place the port on the front I was thinking about painting them all white and painting the inside of the port before installing it. Or painting the baffle black and veneering the rest of the cabinet.

If I place the port on the back I want to veneer the entire cabinet and I won't worry about the look of the port.

Also does anyone have experience veneering over a 3/4" roundover?

[lunchmoney]

Whoops. Don't know why I put the box part in there. You posts have really helped me with the cabinet construction. I hope mine come out as nice as yours.

I was wondering about that. When you painted it did you plug the end of the port with anything or just let the paint enter the cabinet. If I place the port on the front I was thinking about painting them all white and painting the inside of the port before installing it. Or painting the baffle black and veneering the rest of the cabinet.

If I place the port on the back I want to veneer the entire cabinet and I won't worry about the look of the port.

Also does anyone have experience veneering over a 3/4" roundover?

Yeah, it's my important that you're very precise about my ludicrous screen name... don't let it happen again... :

I simply let paint enter the cabinet... didn't plug it... I suppose you could hand paint the inside of the port with a brush prior to installing it into the cabinet... (note to self: do this next time)...

I don't have any experience veneering, but I do know that many people have veneered around corners as tight as 1/2".

[djn04]

So I could hardly sleep last night thinking about how to finish the cabinets. Ok that's a slight exaggeration but. One minute I want to place the port on the back and veneer the next I want to place the port on the front and paint.

Right now I'm leaning towards front port and paint them white.....or black..... or metallic....or..............

I never should have started this I can't get anything else done until I finish these speakers :B

[DeathMonk]

So I could hardly sleep last night thinking about how to finish the cabinets. Ok that's a slight exaggeration but. One minute I want to place the port on the back and veneer the next I want to place the port on the front and paint.

Right now I'm leaning towards front port and paint them white.....or black..... or metallic....or..............

I never should have started this I can't get anything else done until I finish these speakers :B

This is how it all starts

[lunchmoney]

Easy solution to your dilemma: locate the port where it's going to sound best.

That being said, I'm not sure where that would be... although my hunch, from what I've read, would be in the back.

Perhaps others with more expertise could chime in.

[Rolex]

I would place the port in the front. Should be easier to place in the room. In the back could cause issues if you are only going to be 12" off the back wall.

[Carl V]

why not port in on the bottom...
a'la Jon's large floor stander or
Avalon speakers...among many others.

Only concern is port spacing, which isn't too difficult
to work around.

[djn04]

So here's little update. I've finished all the cabinet work and sealed the interior with Minwax Wood Hardener, I've installed the port (on the front), wired the crossover and gave them a test. They sound good even with the baffles just clamped on and played through a cheap 10 year old Sony AV receiver.

Now some pics and a couple questions.




one tweeter is upside down I might drill out another set of ears for the terminals and flip it around.







Is this crossover arrangement OK? I read in a previous post that some arrangements can be problematic. Also the design calls for heavy stuff of the bottom of the cabinet. How do I know when I have enough stuffing?

Thanks.

[Bear]

Show the crossover so that the layout is visible. Placement in the box looks fine, but you want the inductors (coils) not to interfere with each other.

Bill

[---k---]

If you intend on gluing the baffles on, you might want to consider placing the crossovers higher up, where you could get at them if you want to change something. You may like your speakers voiced slightly different than zaph, or who know what. It's just a good idea to be able to remove the driver and pull the crossover out.

Also, same with the poly fill. That looks like a lot. You may want more or less. With that much down there, you'll never be able to find out. I think it would work better also, if it were distributed uniformly.

[djn04]

Does this work?

Image not available

or this one



In my arrangement the red cap in the high pass is vertical and perpendicular to the low pass filter

[djn04]

Ryan-

Thanks for the suggestion. I was planning to glue the baffles. I'm very much a newbie in this and I hadn't considered changing the crossover. I had a difficult enough time soldering the wires to the crossover on my kitchen table I can't imagine trying to swap out caps and resistors through the woofer cutout in the baffle. 8O

I've kinda treated this as a first attempt. I've learned a lot in the process and I'll likely rebuild the cabinets in the future. I'm happy with how they've come out but I already know I can do better.

I'm going to try to even out the distribution of the stuffing and if the crossover arrangement is OK I'll likely leave them where they are.

I experimented with differing amounts of stuffing and more seems to tighten the mid bass and make the bass less boomy.

This is a quote from Zaph design "I call for heavy stuffing at the bottom of the enclosure to reduce the lengthwise pressure node at 140Hz. Not doing so would cause some audible raggedness in the midbass. The difference between enough and not enough stuffing is easily seen in an impedance curve. "

I'm just curious when I'll know I have enough.
Thanks.

[JonW]

Everthing looks excellent! :T These should be some very, very nice sounding speakers when you’re done.

Ryan makes a good point about having things arranged such that you can get at the crossovers and stuffing in the future. I have a speaker with the same drivers and can tell you that, to my ears, the amount of stuffing had a pretty noticeable effect on things. More than I expected. Having just the right amount is great. Too much and the speakers lost a little “top end air” or “clarity” or some other such audiophile babble. And it’s possible you might want to change the tweeter level, too. These drivers make for an *amazing* speaker. (Disclaimer: To my ears, at least. I know some people don't think the expense is justified.) If you hear them and get anything short of amazing, you’ll have to get in there and play around a bit with the tweeter level and stuffing.

Zaph says to keep lots of stuffing on the bottom and he does have a point. I would start with lots of stuffing down there and then tweak to your taste.

Maybe do some critical listening with the box clamped together, so you can get back in easily? And change the stuffing and/or tweeter level a little? Make really sure you’ve maxed out the capabilities of the speaker prior to gluing it up.

Are you going to roundover the edges of the front baffle? I would recommend that if you can.

[djn04]

Yes I planned on gluing the baffles then trimming them with a flush trim bit and then using a 3/4 inch round over on the sides.

Maybe I'll keep them clamped for a while and mess around with the acoustic stuffing a bit. I guess part of my problem with that is I don't truly know what they should sound like as I have no reference. I can say I was surprised by the amount of bass that the woofer produced.

Here's the setup I will be using for testing but unfortunately not for permanent listening.



BTW I drooled over your cabinets but ultimately decided they were outside my ability.

[JonW]

Yes I planned on gluing the baffles then trimming them with a flush trim bit and then using a 3/4 inch round over on the sides.

Maybe I'll keep them clamped for a while and mess around with the acoustic stuffing a bit. I guess part of my problem with that is I don't truly know what they should sound like as I have no reference. I can say I was surprised by the amount of bass that the woofer produced.

Sounds like a good plan. :T

You don’t need a reference, really. Just listen, change something, listen again and then decide if it went better or worse. Easy. Takes some effort and patience, though. But you’ve got speakers that should really pay off with such efforts.

Looks like those are Sonus Faber speakers. I’ve only heard one- something like Domus Grand Piano or some such name. Quite nice. It was years ago and I have not heard the ZRT’s. So it's just a guess, but I might wager that the ZRT’s could beat out the ones I heard.

BTW I drooled over your cabinets but ultimately decided they were outside my ability.

Thanks. They were *way* beyond my skills, too. I just went slowly and learned things along the way. Not the easiest speakers to build but it was worth it to me.

[Dennis H]

Thanks. They were *way* beyond my skills, too. I just went slowly and learned things along the way. Not the easiest speakers to build but it was worth it to me.

Take heart, Jon. If you ever burn out on the whole professor thing, you can always get a job as a carpenter.

[JonW]

Take heart, Jon. If you ever burn out on the whole professor thing, you can always get a job as a carpenter.

Oh my! If I have to rely on my woodworking skills for survival, I would go very hungry. 8O And if I could bring in some cash, somehow, I certainly wouldn't be eating on a straight, flat table that I made. I'd best keep my day job. :P :B

[djn04]

more pics and SUCCESSSSSS!!!!

[Dean100]

Nice work! They look great but the real question is how do they sound?

[fbov]

nice work indeed, but, be patient. Give them a workout, make sure they're broken in to whatever extent they require then take the time to listen to them and allow your senses to discover what's there.

Every speaker sounds great the first time you listen to it, especially if it's your first build. The really good ones just continue to impress...

HAve fun,
Frank

[MattLum]

ZRT Damping materials - is the Madisound kit enough?

Hey there,
I realise it has been some time since this post but I am now where you were - getting organised for my first ZRT build and wanting to do it right. I have the full Madisound kit and a question. Were you happy with the damping materials? There's all sorts of exotic things on-line from felts to viscoelastic paints and the materials from Madisound seem basic by comparison but if they are enough OK then. What are you thoughts? Any other hidden pitfalls I should know about before I start cutting MDF?8O

[neuro]

From the Madisound site:
Internal Dampening Materials
(2) Open cell acoustic Foam Sheet 27" x 42" x 5/8"
(2.5#) Acousta-Stuff complex fiber fill

That looks like good material selection. You could get more exotic but would be in the realm of diminishing returns if not better being the enemy of best (i.e. could make things worse in an effort to get better).
A thick layer of dense viscoelastic paint could damp the cabinet walls, but make sure you have comprehensive bracing before bothering with that. If you're going for an ultimate build you could use bamboo ply for the front baffle and make all the walls double thick (I'd probably do that as opposed to any kind of damping paint). Maybe felt helps, it would go between the cabinet wall and the foam. Similar to the foam in function but denser. Open cell foam is a pretty high tech material, only been readily available for our purposes over the last decade or so. I'm not aware of anything that is better than acousta-stuff for fill, maybe someone else is.

[MattLum]

Thanks so much for the info! I appreciate it!!