THTLP build --- veneering

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DaveMacKay
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Re: THTLP build --- SPL chart

#31 Post by DaveMacKay »

Since hooking up my recently completed THTLP to my stereo, I think it's fair to say that I've been overdoing it with bass. The novelty of having such an awesome amount of bass available has been alluring. In time, I expect that I may dial the THTLP back and reduce the bass. But for now --- WOW!

I configured my receiver to boost the LFE signal 3 dB above my mains. I then used the 5-band PEQ provided by the THTLP's plate amplifier's DSP to tune the THTLP to my liking. Here's a chart from REW showing how my system is performing:
measurements.jpg
Note that:
  • the chart covers the entire 20Hz to 20kHz frequency range, not just the subwoofer range
  • the vertical axis goes from 60 to 95 SPL
  • the chart has had REW's "psychoacoustic" smoothing applied
I'm just learning REW and would welcome any pointers from those who are more familiar with it about how to effectively use the tool.

I will be adding a second THTLP to my system later this winter (it's being built by @Tom Smit). I'm keen to see what difference the second THTLP makes in augmenting the sound and in sorting out some of the deficiencies of my room.

howiez
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Re: THTLP build --- SPL chart

#32 Post by howiez »

Seems like you have a 'peak' from 20 to 100Hz LOL
Enjoy!

jimbo7
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Re: THTLP build --- SPL chart

#33 Post by jimbo7 »

It's better to have too much boom boom than not enough boom
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Seth
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Re: THTLP build --- SPL chart

#34 Post by Seth »

Dave, I used to think there was a universally "right" response curve to tune audio systems to. I didn't know what it was, but I believed it was a thing, and argued the matter more times than I'd like to admit. For a while I thought a flat response curve was "the right curve", but plenty of people I trust (Bruce, Grant, Corona Operator...) were disagreeable in the matter. I have to agree that when I played recorded content through my system tuned flat, it was slightly over bright and the bass was much much lower than what I thought it aught to be. I'd wonder what the sound engineers were thinking. Don't they know people like bass? So, I asked around and people would say things like "if it sounds good, it is good". When they said that, my analytical nature just heard them saying "I don't know". I asked around quite a bit and searched Google like a madman. I finally found a forum that seemed to be primarily populated with pro audio professionals, people who earn a living working live performances. Know what they said? You guessed it. "If it sounds good, it is good."

However, I was able to fulfill a bit more of my curiosity within that conversation, they had a little bit more to add to subject than just the infuriating mantra I'd been hearing over and over. These guys seem to be split in their opinion of a main PA target response curve to tune to. About 50/50. Some tuned their main PA flat and adjusted individual inputs to taste and the others liked to tune the main PA to a curve with a "tilt" to it, requiring less individual channel EQing.

I know you're situation is far from pro audio live performances, so I'll whittle this story down to the point. One of the guys that prefers tuning with a tilt posted a target response curve they shoot for. I tried it out on my system and I like it a lot for recorded content. The bass is sweet, solid, smooth, and impactful without being muddy or overwhelming and the highs are subtle, less obvious, and don't jump out.

Looking at your response curve, it's not all that far off of their target curve.

Untitled.png
Orange is their target, the other traces are their measured result.

If it sounds good, it is good.
Build in process - 2 WH6, one Alpha 6a loaded, one PRV Audio 6MB250-NDY loaded

Two 2x6 shorty SLA Pro's
One T39, 16", 3012LF loaded
Tall AutoTuba, 20" wide, 2x 8" MCM 55-2421
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JensToft91
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Re: THTLP build --- SPL chart

#35 Post by JensToft91 »

Seth! You answered my post in "Extension, SPL perceived sound....", and told me that my mind works like yours. Reading this post is like getting a blast of all my previous frustrations in my face.

I've been on the exact same road as you. I could've written every sentence in your post. And I will back you up. Dave - don't ever fall in to the measurement-trap of "this measures right, so this should sound right". I cannot tell you how many hours I've spent in near depressive state of listening to various speakers tuned flat by the help of Audyssey. I've changed speakers more times than I want to admit, because some measured response SHOULD sound good. I have been searching for the speaker that sound good, while measuring flat (In the listening position). The reality is, that most speakers do, IF and only IF the listener prefers a flat frequency response. If you do not, NO speakers will sound good.

Buttom line: Measurements are fine, but beware - they can pull you into a hole where you don't trust your own ears. I still struggle to shake the feeling, that there's something wrong with my preference - so I still end up tuning my system to something between my preference and "correct". It's the worst trap ever. It's like forcing yourself to drink a wine, that has been praised by reviewers. You hate it - but you should like it. So you spend every night in 10 years, to "learn" how to like it. What a great way to waste a perfectly good opportunity to listening to heartwarming bass and bottle of unpopular whiskey you just happen to like.

To anyone trapped: Read this presentation of room correction blind test. Edit: Removed my first conclusion of the results, as I had misunderstood them. The right conclusion is that the balance is related to the most likable sound - and it's not a flat response.

https://www.petoindominique.fr/pdf/The% ... oducts.pdf

Seth - I know you'll love that link :hyper:

DaveMacKay
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Re: THTLP build --- SPL chart

#36 Post by DaveMacKay »

Seth and Jens, thank-you for your posts.

It seems as if I was walking a road that you've already been down. I'm happy to hear what you concluded.

I think I'm going to stop adjusting my system towards some expert's arbitrary curve (i.e., mostly flat) and just enjoy what I like!

JensToft91
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Re: THTLP build --- SPL chart

#37 Post by JensToft91 »

In addition, I have found that I initially set the bass to my liking. But after having watched a few movies I tend to dial it down over time. I think this is because that I'm focused on the bass response when I initially set it up. But while watching movies, your attention will shift. You might suddenly find the bass bloaty or even annoying because it intrudes on voices and is "overreacting" to smaller effects. I then dial it down. Maybe effects seems to "off" now - and this might be the right time to EQ. The level adjust everything - but you might like the sub-bass to be hotter, compared to the 40-100 hz region. Just like the graps are showing.

I even heard of people that highpass the subs during music listening, because they don't like the 20-40 hz region.

It's all preference :-) And yes. Enjoy your system!

DaveMacKay
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Re: THTLP build --- veneering

#38 Post by DaveMacKay »

The return of good weather has enabled me to move the car out of the garage and to set up for some woodworking. Job #1 is to improve the appearance of the THTLP I built last fall by veneering the unit.

After vacillating for way too long, I decided to veneer the THTLP in sapele. I used two 4' x 8' sheets of paper-backed sapele veneer for the THTLP and a half-gallon of Heat Lock iron-on veneer glue.

In this photo I'm getting ready to apply the first sheet of veneer to a side. I'd already applied edge-banding to the top of the THTLP and have taped off the banding on the side adjacent to where I'll be installing the sheet of veneer so that I don't get glue on the edge-banding.
IMG_2414.JPG

This photo shows the veneer that I applied to the bottom of the THTLP:
IMG_2415.JPG

This photo shows the glue applied to a sheet of veneer and one side of the THTLP.
IMG_2416.JPG
The glue needs to set up for 30-45 minutes before setting the veneer on the panel. The glue is then activated by ironing the veneer to the panel.


Here's what it looks like with the veneer applied:
IMG_2417.JPG
After letting the glue cure for about an hour, I used a flush-cutting bit in a router to trim the veneer to fit the THTLP exactly.

That process is repeated for the other sides. The tricky part was dealing with the "notch" in the THTLP. I made templates out of poster board and used those templates to select matching veneer and to cut the pieces to size.

Here's what the THTLP looks like after it's been completely veneered:
IMG_2423.JPG
I used a razor knife to cut the bottom from the rest of the THTLP. If you look closely you can see the cut line.

This was my first venering project of any size. It wasn't as hard as I feared. Because of the time required to let the glue set (before applying the veneer) and cure (before trimming the veneer), it's not a quick process. All told, it took me 3 days to veneer the THTLP.

I haven't yet applied a finish. I plan to apply a Rubio Monocoat clear finish to the THTLP.

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J_Dunavin
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Re: THTLP build --- veneering

#39 Post by J_Dunavin »

ooooo that turned out really nice!
Where did you get the veneer from?
2 - OTop8
2 - T39
8 - DR200
2 - DR250
9 - T24
6 - T45
1 - Auto Tuba

DaveMacKay
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Re: THTLP build --- veneering

#40 Post by DaveMacKay »

J_Dunavin wrote: Tue Jun 28, 2022 8:31 am ooooo that turned out really nice!
Where did you get the veneer from?
Thanks! I hope to apply the finish tomorrow. I'll post photos when that's done.

I purchased the veneer from a local supplier (Exotic Woods in Burlington, Ontario). They stock a large selection of veneers. The 4'x8' sheets of papebacked quarter-sawn sapele veneer cost CAD$119/sheet.

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Seth
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Re: THTLP build --- veneering

#41 Post by Seth »

My hat's off Dave. Thought about it, but have never done it. Looks really good :thumbsup:
Build in process - 2 WH6, one Alpha 6a loaded, one PRV Audio 6MB250-NDY loaded

Two 2x6 shorty SLA Pro's
One T39, 16", 3012LF loaded
Tall AutoTuba, 20" wide, 2x 8" MCM 55-2421
TruckTuba, 8½" wide, 2x 8" MCM 55-2421

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Tom Smit
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Re: THTLP build --- veneering

#42 Post by Tom Smit »

Lookin' good, Dave!
TomS

DaveMacKay
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Re: THTLP build --- veneering

#43 Post by DaveMacKay »

Tom Smit wrote: Tue Jun 28, 2022 10:11 pm Lookin' good, Dave!
Thanks Tom!

The one you built for me is next in line for veneering.

DaveMacKay
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Re: THTLP build --- veneering

#44 Post by DaveMacKay »

I finished veneering my two THTLPs a few weeks ago. I'm pretty pleased with how they turned out.
THTLPs.png
My THTLPs are minimum-sized (15"x18"x72"). I built one of the THTLPs (the right subwoofer) and Tom Smit built the other (the left subwoofer). Each is powered by a Dayton SPA250DSP (250 watt) plate amplifier and uses a 12" driver. To get them to play well in my room I ended up not making use of the DSP capabilities of the SPA250DSP and using a MiniDSP 2x4HD to "dial them in" instead.

I used two sheets of Sapele paper-backed veneer and a half-gallon of HeatLock glue for each THTLP. The dimensions of the THTLP meant that --- although two sheets were necessary --- two sheets would likely be sufficient for a much larger-sized THTLP. I finished the THTLPs with two coats of Rubio Monocoat "Pure". It was easy to apply and gives a nice finish. J_Dunavin provided the BFM badges that I put on each subwoofer.

I have placed them in my room as per this diagram:
subwoofer placement.png

I'd like to thank the members of the forum for the information, advice, and encouragement that you gave me during the build. I'm especially grateful to Bill Fitzmaurice for the excellent design and plans, to Tom Smit for building the second THTLP, and to J_Dunavin for the badges.

Now I'm in the midst of veneering my speakers (Klipsch La Scalas) in the same veneer.

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Tom Smit
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Re: THTLP build --- veneering

#45 Post by Tom Smit »

I, too, would be pleased with how they look! Good job.
TomS

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