ZMV5 Build Pics and Q's

[AlanH]

I thought I'd build Zaph's new ZMV5, since I already had built the L15/27TFFCs that they replace. Plus, for about $100 in parts I thought it was a good place to get some practice on my veneering and finishing skills since my previous attempts used the pre-finished PE cabs. I've attached a pic of the ZMV5s and another showing a ZMV5 alongside the L15/27TFFC, which I built using PE's curved cabinets.

Some notes: 3/4" MDF all around, the front baffle is removable, the veneer is flat-cut cherry finished using General Finishes Seal-a-Cell and Arm-R-Seal.

The big change I made from Zaph's standard design was to opt for a front slot port rather than a rear-mounted flared tube. Basically I didn't have port tubes handy,plus I like the look of the finished slot port. This brings up a question though...

After I started building these boxes, I saw it mentioned on a thread here (which I can't find again) that some drivers are only suitable for port tubes and not for slot ports. I hadn't heard this before and I was wondering, can someone can shed some light on the driver requirements for tube vs slot ports?

Anyways, the speakers have been up and running for 24 hours and while I haven't done any critical listening or A/B comparisons yet, I'm very happy with the way the ZMV5s sound, so thanks to Zaph for another great (and high value) design!

[Dennis H]

After I started building these boxes, I saw it mentioned on a thread here (which I can't find again) that some drivers are only suitable for port tubes and not for slot ports. I hadn't heard this before and I was wondering, can someone can shed some light on the driver requirements for tube vs slot ports?

I've never heard that either. Doesn't make any sense to me.

[Jed]

Dennis is right, a properly tuned slot port will do the exact same thing as a round port.

By the way your speakers look great.

[WillyD]

I really like the finish man! Great job.

[Rolex]

The real question is, how do they sound compared to the L15 design?? I have the drivers for this design as well, but am building the sr71 first.

[JohnInKY]

Those are handsome speakers indeed. Great looking job. I doubt the speaker will "know" whether it's driving a slot or a port. Maybe the discussion was about port resonance or turbulence? Shouldn't make any difference as long as the tuning is equivalent.

John L.

[JonW]

Alan,

Those speakers look *amazing*! :T

Nice Photoshop work. : :P :W

Seriously, they look super. :T So how did you get the veneer around the roundover, in the port, etc. Or are the front edges and port just finish over MDF and no veneer?

Along with everyone else, I think you're fine with the slot port. Give them some listening time and then we'll bug you about how they sound.

[DeathMonk]

Those look really good

I was thinking about building a set of these. Actually, almost every project I see I want to build now. It's safe to say I am addicted to this hobby

[AlanH]

Thanks to all for the complements!

I'm glad to learn that the slot port should be okay. I used this calculator to get the dimensions for the port tuning. It's a nice and easy-to-use tool that also reminds noobs like me to keep the width:height ratio less than 9:1.

The real question is, how do they sound compared to the L15 design?? I have the drivers for this design as well, but am building the sr71 first.

My early impression is that the midrange and top end is every bit as good as the L15/27TFFC. The low-end seems to roll off earlier than the L15. Again that's an early impression without doing an A/B comparison, though I'll admit for a 5" driver I always was impressed at how well the L15 did on the low end. Overall I'm happy so far, and with a sub the ZMV5s are very easy to listen to...

Alan,

Those speakers look *amazing*! :T

Nice Photoshop work. : :P :W

Seriously, they look super. :T So how did you get the veneer around the roundover, in the port, etc. Or are the front edges and port just finish over MDF and no veneer?

Are you questioning my integrity by suggesting that I doctored the data?

I used HeatLock adhesive for the veneer. For the 1/2" round-over I just bent the veneer around the corner while ironing (note that the round-over is parallel to the veneer grain). It worked like a charm. I then trimmed the ends by hand with a veneer saw. I'd never veneered anything before but the HeatLock seemed VERY easy to use.

As for the slot port, I just bit the bullet and veneered the inside face of the MDF too (this was done before cabinet assembly). This has the added benefit that the inside of the cabinet looks pretty nice when the front baffle is off.

I was thinking about building a set of these. Actually, almost every project I see I want to build now. It's safe to say I am addicted to this hobby

I hear you about the addiction...The nice thing about building these is that for a small parts investment you get a great sounding speaker...Now I'm thinking about building a crazy Scan-Speak 2-way with fancy faceted cabinets that I saw floating around here...

[JonW]

My early impression is that the midrange and top end is every bit as good as the L15/27TFFC.

Although only an early impression, that’s good news because I really liked what I heard of the L15/27TFFC.

Are you questioning my integrity by suggesting that I doctored the data?

No, I’m not questioning your integrity. I’m flat-out calling it dodgy. :P :W

I used HeatLock adhesive for the veneer. For the 1/2" round-over I just bent the veneer around the corner while ironing (note that the round-over is parallel to the veneer grain). It worked like a charm. I then trimmed the ends by hand with a veneer saw. I'd never veneered anything before but the HeatLock seemed VERY easy to use.

Good to know. If it can bend veneer around a tight 1/2” roundover with the veneer only grabbing to one flat cabinet side, it must work really well. I may have to try that out on my next project.

As for the slot port, I just bit the bullet and veneered the inside face of the MDF too (this was done before cabinet assembly). This has the added benefit that the inside of the cabinet looks pretty nice when the front baffle is off.

Good idea. It’s more work but it definitely pays off later, as we can see from the pics.

Now I'm thinking about building a crazy Scan-Speak 2-way with fancy faceted cabinets that I saw floating around here...

That’s insane talk, man! Someone call a doctor. This man must be feverish and ker-AY-zee! Turn around and walk away while you still can…

[Undefinition]

After I started building these boxes, I saw it mentioned on a thread here (which I can't find again) that some drivers are only suitable for port tubes and not for slot ports. I hadn't heard this before and I was wondering, can someone can shed some light on the driver requirements for tube vs slot ports?

A driver doesn't care whether the vent is rectangular or circular. Perhaps the point of the thread was speaking more to the effect that sometimes a slot port is just too wide an opening, and requires a vent length that is impractical. Still, you could make the slot port narrower, and thus the length might be usable again.

[jkrutke]

My early impression is that the midrange and top end is every bit as good as the L15/27TFFC. The low-end seems to roll off earlier than the L15. Again that's an early impression without doing an A/B comparison, though I'll admit for a 5" driver I always was impressed at how well the L15 did on the low end. Overall I'm happy so far, and with a sub the ZMV5s are very easy to listen to...

Thanks for the comments. You're probably one of the only people who will ever make the comparison with the old L15 design. You confirmed what I was shooting for, equaling or exceeding the performance of that system in the mids and highs but for a lot less money. I know the L15 is going to be better in the bass, but that was less of a priority for this design. Your build looks really good.

It's been a couple years since I did a slot port, but I can share some of the things I found. First, when the slot was near an edge, it was always tuned much lower than calculations would predict. After that discovery, I built slot ports far shorter, and then just added glued-on pieces of wood on the inside to add length as required, with the last piece being a quarter round for smoother airflow. If you haven't checked your impedance curve, I bet you'd be surprised with where your tuning is at. It might be low, and that might favor a lean tonality.

It's probably not an issue with small cabinets, but with the couple of larger slot ports, I ended up adding a thin rib down the middle (1/8" hardwood) to help limit flexing.

[happy]

Just out of curiosity, is the ZMV5 a 4 or 8 ohm speaker?

[AlanH]

It's been a couple years since I did a slot port, but I can share some of the things I found. First, when the slot was near an edge, it was always tuned much lower than calculations would predict. After that discovery, I built slot ports far shorter, and then just added glued-on pieces of wood on the inside to add length as required, with the last piece being a quarter round for smoother airflow. If you haven't checked your impedance curve, I bet you'd be surprised with where your tuning is at. It might be low, and that might favor a lean tonality.

Thanks for the tip Zaph! Is this effect different than the end correction term, which takes into account that one side of a slot port is longer than the other as described here? If so then my port is probably too long... :cry: Since the only measurements I can do right now are with an LCR meter, I can't check to be sure. (Once my wife and I move I'll have more room to dedicate to this hobby so I'll be able to solve this problem)

[69Stingray]

Is this effect different than the end correction term, which takes into account that one side of a slot port is longer than the other as described here?

Slot plot do suffer from end correction because the inner wall extends into the cabinet (making the port effective longer). Round ones do to but most equations kind of take that into account. So, if your original calculations did not take into consideration this end correction, then you will probably be off a couple Hz or two.

[jkrutke]

Thanks for the tip Zaph! Is this effect different than the end correction term, which takes into account that one side of a slot port is longer than the other as described here? If so then my port is probably too long... :cry: Since the only measurements I can do right now are with an LCR meter, I can't check to be sure. (Once my wife and I move I'll have more room to dedicate to this hobby so I'll be able to solve this problem)

That page includes a partial end correction factor, so it might not be too far off, but it's still likely tuned low. In fact, I'd say on average, all calculated port lengths are usually too low, by 3-8 Hz. This is just years of experience measuring tuned ports. I always recommend playing with the tuning to taste, something that is unfortunately hard to do with a slot port. I wouldn't worry about it too much, bass performance is not the strong point of the ZMV5, and I recommend a sub in any case.