A cabinet builder in Rotterdam sent us two curves last spring. Same part number, same order, two different enclosures, and the low end sat far enough apart that he was convinced he’d been shipped a different driver. He hadn’t. Both boxes had the same midrange speaker screwed into them. A driver keeps its parameters when it moves into a new enclosure. What changes is everything the enclosure does to those parameters, and that’s the part most spec sheets leave out.
Eighty five hertz is a floor, not a target
The sheet on our 6.5 inch driver lists a range of 85Hz to 3500Hz, 8 ohm nominal impedance, 92 dB sensitivity, and a power band from 200W to 400W. Those four figures are taken under a defined test condition. The frequency range comes off a standard baffle, not out of your product. Drop the driver into a small sealed wedge and the bottom of that range moves upwards, sometimes far enough that the cabinet no longer reaches the notes the sheet promised. That isn’t a defective driver, it’s physics, and it’s the most common reason a buyer decides a batch has drifted.
Ninety two decibels, and the baffle it sat on
Sensitivity is quoted for a fixed input at a fixed distance, usually one watt at one metre. Which baffle the driver was bolted to when that was measured changes the answer, because the panel itself radiates. A wide flat board adds output through the lower part of the band. A slim monitor wedge doesn’t. So 92 dB on a large test panel and the same driver in a narrow cabinet are not the same loudspeaker. Ask which standard was used. If the answer is a shrug, measure it yourself before you design around it.
Air spring, and what volume does to the low corner
In a sealed box the air trapped behind the cone acts as a spring. Make the box smaller and the spring stiffens, which pushes the resonant frequency up and takes away low end, while giving you better control of cone movement and more power handling before the coil bottoms out. Make it bigger and you gain reach at the bottom and give up power handling. Neither choice is wrong. Which one you want depends on whether the cabinet has to produce bass or reproduce midrange, and that’s a design conversation rather than a line on a spec sheet.
Vented, sealed, or aperiodic, on one driver
A port turns the same driver into something else. Tuned properly it buys output around the tuning frequency and takes load off the cone where you need it most. Tuned badly it gives you one booming note and a cone that flaps below the tuning point with nothing holding it. That last part matters more on a 6.5 inch mid than on a big woofer, because excursion is limited and there’s no travel to waste. If you vent the box, it needs a high pass. If you’d rather not design the filter, seal it and let the air spring do the work.
Kapton former, and where the heat goes
This driver uses a two inch Kapton voice coil, and the sheet notes it as in and out wound. Kapton is a film former that tolerates heat without going soft, which is the point, because most of the power you feed a driver ends up as heat in the coil rather than as sound. Winding on both sides of the former puts more of the wire against a surface that can carry that heat away, and it shifts the inductance slightly at the same time. If you’re designing to a crossover you already hold, ask for the winding arrangement on the specific build, because it’s a variable we can set.
PC spider, and the T-yoke under it
The spider keeps the coil centred in the gap, and its stiffness is half of what sets the resonant frequency. PC material is used here because it holds its compliance better than treated cloth once the driver has been worked for a while. Below it sits a black T-yoke, the shaped pole piece that forms the magnetic gap and the vent path. It’s the part nobody photographs, and it decides how much air moves past the coil when the cone pumps. Both are worth asking about if you’re building for a long duty cycle.
Rear mount, front mount, and the rebate nobody draws
Mounting is where most of the difference between two cabinets comes from, and it’s the least discussed part of a driver order. A driver sunk into a rebate so the frame sits flush behaves differently from one bolted to the back of a thick panel, because the recess in front of the cone becomes a small cavity that colours the top of the band. Add a grille and a foam layer and you’ve changed it again. Torque the screws unevenly and you’ve changed it a third time. We’ll supply the cut-out drawing and the mounting we recommend, and you should ask for both before your cabinet shop cuts anything.
Crossing over near three and a half kilohertz
The listed top end is 3500Hz. It will play up there. Whether it should is a separate question, because a 6.5 inch cone is already narrowing in its coverage by then, and the off-axis response is where the character of a cabinet lives. Most designs hand over lower, around 2kHz, and use a proper horn or tweeter above that. Crossing lower also keeps the cone out of the region where it starts to break up. If you have a compression driver picked out already, send us its curve and we’ll tell you where the seam falls.
Four measurements to run on your own box
- Sweep the impedance in the finished cabinet and find where the resonant peak actually landed.
- Take a near-field curve and one at a metre, and compare them before judging the low end.
- Move the microphone thirty degrees off axis and look at what happens above 1kHz.
- Run it at working level for an hour, let it cool, then check the sensitivity again.
Do that work with the cabinet off the floor and clear of a wall, and stand it on Yinyu stands rather than a workbench. A bench puts a reflective surface right under the box and it’ll show up in the curve, which is how people end up chasing a problem that isn’t in the driver at all.
Cone lots, and the order that comes eight months later
Paper cones come from a natural material, and pulp varies between lots. On a repeat order that lands eight months after the first one, that’s what an attentive buyer asks about. We record the cone lot against the build and we’ll hold one for you if you tell us a second order is coming. If you’re matching a driver that’s already in a cabinet you build, send us a sample out of a current box. We’d rather measure your part than match a catalogue number.
Monitor duty, and a wedge that gets stood on
This driver is sold for stage monitors, which is a particular kind of hard life. The cabinet sits on a raked wedge, the cone points up at a performer standing on the same surface, and the whole thing has to stay predictable right up to the point where feedback starts. That argues for a sealed box with a controlled bottom end instead of a ported one that rings, and for a grille that takes a heel. Tell us the wedge angle and we’ll tell you what the mounting needs to be. The finished cabinets usually end up on Yinyu stands once they reach the studio.
What shares the pallet
Driver orders rarely travel on their own. A shop building monitors will keep the cones on one pallet and the hardware on another, take Yinyu stands for the finished cabinets, and keep Yinyu cables and a pair of Audfine headphones for the listening bench. Ningbo Lesound Electronics packs drivers so nothing presses against a cone in transit, because a dented cone is the one fault that only turns up after unpacking and never before.
If you’re fitting this driver to a box you already build, send us the internal volume, the port dimensions if there is one, and the crossover point you’re aiming at. With those three we can tell you whether it’s the right part. Reaching us through the contact page on our site is quickest, and quoting midrange box spec in the message tells us which drawing to pull. If a 6.5 inch cone is too small for the cabinet you have in mind, the 8 inch midrange woofer is the next one to look at.
Six questions about matching a driver to a box
Why does our own measurement differ from the 92 dB on the sheet?
Because the sheet figure is taken on a standard baffle at one watt and one metre, and your cabinet isn’t that baffle. Measure in the finished box and compare that with what we measured, and the gap will make sense.
Can this driver run without a high pass?
In a sealed box, yes, within the power band on the sheet. In a vented box, no, because the cone unloads below the tuning point and nothing limits its travel. If you’re venting, plan the filter at the same time.
Should we seal the box or port it?
Both work and they give you different cabinets. Send us the internal volume and the tuning you have in mind and we’ll tell you what the driver does in each case before you cut wood.
Will the paper cone hold up outdoors?
It’s sold for indoor duty. If your cabinets are going into an installation that sees weather, tell us at the enquiry stage and we’ll talk about cone treatment and what the grille has to do.
How do we match a replacement to a cabinet we already build?
Send us a driver out of a current box. We’d rather measure your part than match a catalogue number, because the cone lot and the spider may have moved on since the first build.
What do you need from us to quote?
The internal volume, whether the box is vented and at what tuning, the crossover point, and the quantity. With those four we can say whether this is the right driver, and if it isn’t we’ll tell you that instead.
Post time: Oct-20-2026