Overnight Sensation build

[Paul Carmody]

yeah, that's a crapload of bass. It's hard to know exactly what might be causing that. It could be that the port tuning is off on the woofer, or that some components are out of order on the XO

[Kornbread]

The DTA120 was brand new. Just to be sure something wasn't amiss with it and skewing the readings I hooked up the tk2050 Sure board that has been driving the Linaeum/FaitalPro project and came up with basically the same results when measured the same way. Green trace is the DTA120.




Also measured port and box dimensions then recalculated volume. The port is 2" id, 3"long. The speaker measured 7"wide x 9"deep x 32"tall. Solid board cut on mitered 45 should give an internal volume of 5.5" x 7.5" x 32" ~1320in^3, 1/4" concrete panel on all but front/top/bottom brings inner dimension to approx. 5" x 7.25" x 32" = ~1160. Minus three braces ~30in^3 which = ~ 1130in^3 =18.52L. The design called for, "around 21L." Does the math look ~about right?

Unibox comes up with this for 21L and 18.5L. with a port of 2" x 2.75 and 2" x 3". Apparently I have done something wrong in the crossover. What is it???

[Millstonemike]

Maybe you already have resolved this ... measure another speaker under the physical same conditions. That may tell you whether it's measurement error or a problem with the OS.

Do they sound boomy? Do the woofers bottom at lessor volumes? That may point to box/tuning issues.

[Millstonemike]

Is this too much dampening?

Your box model's suggest a port over 8". In the pic, it likes like less than half that.

[Kornbread]

Maybe you already have resolved this ... measure another speaker under the physical same conditions. That may tell you whether it's measurement error or a problem with the OS.

Do they sound boomy? Do the woofers bottom at lessor volumes? That may point to box/tuning issues.

Yep, easy to hear it and the cones be banging away. Something is waaaaaaaaaaay off. I must say, even though it's just plain ole light and cheap pine board, adding the cement board really deadened the cabinet.

Your box model's suggest a port over 8". In the pic, it likes like less than half that.

In Paul C.'s write-up he says tune to 50hz, f3 of 39, and use a 2" dia by 3" length vent. That's where the vent size came from. On the bottom of unibox there are tabs for sealed, vented, etc. with more graphs showing power handling, port speed, etc. On the vented tab it shows vent size as 2" x 2.75" for 21L and 2" x 3.14 for 18.5L On the design page, (the pics in post #47,) a pop up box says that's, "the suggested min. diameter. Check with port speed graph."

Checked the woofers to be sure a wire didn't get mixed up, they're in phase with each other.

Working with the minidsp for crossover and correction was such a breeze compared to this.

My apologies if I sound a bit critical Millstonemike, it's not intended. I do appreciate the help. When I finally figure out what went wrong, I'll probably kick myself in the bum.

[Millstonemike]

Yep, easy to hear it and the cones be banging away. Something is waaaaaaaaaaay off. I must say, even though it's just plain ole light and cheap pine board, adding the cement board really deadened the cabinet.



In Paul C.'s write-up he says tune to 50hz, f3 of 39, and use a 2" dia by 3" length vent. That's where the vent size came from. On the bottom of unibox there are tabs for sealed, vented, etc. with more graphs showing power handling, port speed, etc. On the vented tab it shows vent size as 2" x 2.75" for 21L and 2" x 3.14 for 18.5L On the design page, (the pics in post #47,) a pop up box says that's, "the suggested min. diameter. Check with port speed graph."

Checked the woofers to be sure a wire didn't get mixed up, they're in phase with each other.

Working with the minidsp for crossover and correction was such a breeze compared to this.

My apologies if I sound a bit critical Millstonemike, it's not intended. I do appreciate the help. When I finally figure out what went wrong, I'll probably kick myself in the bum.

Sorry, Just got confused by your model's port length of 21.88cm port length. I see Paul's design calls for the 2" x 3" port.

Here's a question: Do you have the right B4N woofer? There are 2 versions and the PE recommended vented box sizes for each are significantly different.

[Paul Carmody]

I'm looking at your crossover photo, and the wiring of the cap has me all confused. It almost looks like you have the C4 cap in series with the woofer. Could you possibly re solder that portion of the circuit?

Edit: looking more... maybe not. it's hard to tell where the wires are touching vs. overlapping.

[Paul Carmody]

Also, where do you have these positioned? Are they in a corner?

[Kornbread]

Here's a question: Do you have the right B4N woofer? There are 2 versions and the PE recommended vented box sizes for each are significantly different.

PE's Overnight parts kit lists 297-429 as the woofer. The invoice says 297-429, but I may pull them out and double check something didn't go wrong there.

I'm looking at your crossover photo, and the wiring of the cap has me all confused. It almost looks like you have the C4 cap in series with the woofer. Could you possibly re solder that portion of the circuit?

C4 would be the 6.8uf. It's just after the .22uf then straight to common. Confused I am, way too often.

Also, where do you have these positioned? Are they in a corner?

Measurements were taken on the outside upper deck, open to the yard on three sides. The nearest wall is ~14' away. Mic was 1meter on tweeter axis.


If I get the yard work done before dark, (the mosquitoes are horrid,) I'll disconnect the crossover and take everything outside and measure just the woofers.

[Millstonemike]

PE's Overnight parts kit lists 297-429 as the woofer. The invoice says 297-429, but I may pull them out and double check something didn't go wrong there.

I ordered a Peerless 830945 5.5" Woofer from M**sound, They shipped the peerless 830946 6.5" woofer. And the other B4N may likely behave as you described.

[Kornbread]

Measurements taken outside same setup as before. Had to turn the amp off while connecting/disconnecting each woofer so the levels don't match exactly. Crossover was bypassed.
Top b4n, bottom b4n, both b4n's in phase, and with vs without crossover.

[Paul Carmody]

What sort of measurement method does REW use? I'm not familiar with it. Is it MLS, RTA... ? Sent from my XT1575 using Tapatalk

[Kornbread]

Does this answer help? Here's the help file.

REW uses a logarithmically swept sine signal for its measurements.

http://www.roomeqwizard.com/REWhelp.pdf

[thekorvers]

In my humble opinion the tuning is too high. Not to criticize Paul's design, as I have a great deal of respect for him and his designs, but the 50 Hz tuning creates a substantial peak at 50-55 Hz. IMO a tuning of 38-39 Hz would work better in most rooms (yes, I am aware that measurements were taken outside). Try extending the port to 5" and see if that helps.

[Millstonemike]

Trying to break it down logically ...

Design? Doubtful it's the design coming from PC (like TC - Top Cat ).

CrossOver? You get the same response curve when bypassing the XO. Note the higher amplitude w/o XO is likely due to the loss of a consistent volume setting between measurements as Kornbread has stated.

Box Size? The net volume was undersized (18L instead of the design's 21L). But models for this and even smaller volumes do not explain the 20dB hump in the measurements. The box was highly damped (cement board), braced and completely lined with foam. Could it be a severe leak as if a major portion of panel glue up didn't take? Do both the left and right speakers exhibit the same issue?

Measurement Error? Likely not as Kornbread has stated "yep, the cones be banging away. Something is waaaaaaaaaaay off."

Test Signal? Are the woofers being driven with this signal? Some coincidental issue with the power electronics? A test signal anomaly? Unlikely and easy to eliminate.

Driver Failure? Independent measurements of each driver show the same response. Not sure if the second speaker was also tested. A a bad run from HiFi?

Driver Mismatch? The wrong B4N variation delivered from PE? Validate color of the metallic cones against PE site pics, and, mfg part number on driver.