BillFitzmaurice.info

I'd appreciate some help in answering a question that I've been asked several times.

I have one (soon to be two) THTLP subwoofers accompanying my Klipsch La Scala speakers. Because of its size, the THTLP attracts a lot of attention. Most of my friends, upon seeing the THTLP, want to know why I felt something so big was needed and what it would compare to. That sets me off on a talk about how a horn is different from a direct radiator. I talk about air displacement and use Bill's analogy of paddling with a pool cue versus a paddle.

Eyes glaze over. Women cluster around my wife to offer support.

I've mentioned that, according to the THT web page (https://billfitzmaurice.info/THT.html), comparable speakers would cost around US$2500 (roughly CAD$3200). That seldom impresses when I tell them that the THTLP cost about CAD$2000 even though I built it myself.

I'm then asked what would provide equivalent/comparable performance to my THTLP (which has a 12" driver). Essentially, they are interested in knowing what a comparable commercially available subwoofer would be in terms of:

• size and number of drivers

• ported or sealed

• cost

An answer like "to get performance comparable to the THTLP, you'd need two 18" drivers which would require a cabinet nearly as big" would be perfectly satisfactory, albeit incomplete.

What sort of simple answer could I give folks who are curious, but not really conversant in audio?

I hope that $2k includes the cost of the tools you bought to build it with.

Yeah, that seems really high for a driver and some plywood.......I would figure you should be able to build it for under $700 with a premium driver and baltic birch.....$500 before the wood prices shot up.

Bill Fitzmaurice wrote: ↑Sun Feb 20, 2022 1:05 pm I hope that $2k includes the cost of the tools you bought to build it with.

My Mistake. I had included the cost of the driver and plate amp for both speakers in the cost for one.

Here are the costs (in CAD$) for the THTLP I built:

• THT, THTLP and jig plans $32.52

• Plywood for 1 THTLP $323.18

• CINCH barrier block connectors $20.00

• Subwoofer driver, gasket tape, amp enclosures $422.23

• SPA250DSP plate amplifier $366.94

• PL Premium, Caulking $37.75

• Misc lumber $31.91

• Rubber feet $15.76

That totals CAD$1,250.29 (about US$985)

Cost aside, any suggestions on how to answer the question?

Easy: 'Have you ever heard anything else that sounds as good?' Then cue the crickets.

It's like when people ask me why I drive a BMW: Because I can.

DaveMacKay wrote: ↑Sun Feb 20, 2022 3:47 pm Here are the costs (in CAD$) for the THTLP I built:

• THT, THTLP and jig plans $32.52

• Plywood for 1 THTLP $323.18

• CINCH barrier block connectors $20.00

• Subwoofer driver, gasket tape, amp enclosures $422.23

• SPA250DSP plate amplifier $366.94

• PL Premium, Caulking $37.75

• Misc lumber $31.91

• Rubber feet $15.76

That totals CAD$1,250.29 (about US$985)

Wow.....things like the driver and plywood are way higher than the US.....even with the exchange rate. My T39s were about $700......a pair!

Bill Fitzmaurice wrote: ↑Sun Feb 20, 2022 5:53 pm It's like when people ask me why I drive a BMW

When I get asked why my speakers are so big. I tell them that I am compensating for something. We all compensate in our own ways.

Subwoofers are the largest part of a speaker system are they not. Don’t your La Scales scale the THTLP into proportions somewhat? I wanna know who is capable of questioning about the large subs but not having equally as many questions about everything else.

I refer loosely to Hoffman’s iron law, I tell people when it comes to sound you have three major elements to the equation.
Size
Output
Cost

I say that you can have any two but the other will be in opposite. If you want small and cheap it won’t have much for output. If you want it small but powerful it will cost a fortune. If you want it loud and clear but cost effective than the equipment won’t be small. I explain that I want the most affordable option but do not want to compromise output, so my equipment must be this large to make that happen. I realize that this is not Hoffmans iron law exactly but it is in part the origin of this narrative.

ACUA wrote: ↑Mon Feb 21, 2022 11:24 am I wanna know who is capable of questioning about the large subs but not having equally as many questions about everything else.

People who think Bose sound good?

Nothing drives home the difference harder than actually trying to get direct radiator subs to perform to the same criteria as a horn design.

One could arm-chair quarterback this by suggesting a comparison of the Simplex HT subs to the any of the horn designs, and by the numbers, that's roughly four 15" to 18" loaded cabs to achieve equivalent SPL that a single 10" or 12" is able to deliver in the horn. MOST notably when a person leans on the volume knob with the really low stuff. But that's not the whole pie...because then there's the inherent distortion to contend with for taking that route...on top of total system cost.

I've spec'd and setup a couple of 2.1 systems using direct radiators. It always costs more, requires more amp power, and has more distortion than the horn sub option. The trade-offs primarily being space and limited "full-tilt" capability.

Closest commercial design equivalent to the THTLP? That would be the Danley DTS-20.

I've gotten a single sealed 12" to sound very good, but a person has to be sitting right on top of it, and even so, it'll be chewing through almost a full watt or two:

https://www.youtube.com/watch?v=7sYx5Rq0aeo

Versus a single 8" in the Auto Tuba just coasting along on a milliwatt, poised to shred the entire room:

https://www.youtube.com/watch?v=tsnEg_V2mo8

One other thing...

The eyes glazing over during the OP's explanations is the cue to just lock it up and talk about something else. Recognize a rhetorical question when you see it...try not to take offense to it, and move on to something else interesting for both parties.

Could never figure out the wife/sub/angst thing though...my Mrs. loves her bass. Impressed that she never blew up her Auto Tuba...and trust me there were days I could hear her from a block away trying her damnedest.

ACUA wrote: ↑Mon Feb 21, 2022 11:24 am When I get asked why my speakers are so big. I tell them that I am compensating for something.

Once when dialing in my two T-60s for a (modern art? Found sound, train recordings looped and modded, etc) audio show I had a few onlookers from the venue ask about them. I played some bass heavy music (no idea what it was now) and asked them what kind of driver situation they thought I had in them. They guessed 4 18"s or 8 15"s. They barely believed me when I told them one 15".

Radian wrote: ↑Mon Feb 21, 2022 3:07 pm One could arm-chair quarterback this by suggesting a comparison of the Simplex HT subs to the any of the horn designs, and by the numbers, that's roughly four 15" to 18" loaded cabs to achieve equivalent SPL that a single 10" or 12" is able to deliver in the horn. MOST notably when a person leans on the volume knob with the really low stuff. But that's not the whole pie...because then there's the inherent distortion to contend with for taking that route...on top of total system cost.

I've spec'd and setup a couple of 2.1 systems using direct radiators. It always costs more, requires more amp power, and has more distortion than the horn sub option. The trade-offs primarily being space and limited "full-tilt" capability.

Closest commercial design equivalent to the THTLP? That would be the Danley DTS-20.

Thanks! That's exactly the sort of info that I was hoping for.

Now I need to find some music to demo the THTLPs that will really allow them to shine.

DaveMacKay wrote: ↑Mon Feb 21, 2022 11:06 pm Now I need to find some music to demo the THTLPs that will really allow them to shine.

Perhaps something like these?

Don't count on any of those going that low, by about an octave. The only musical instruments capable of that are the largest pipe organs.

Bill Fitzmaurice wrote: ↑Tue Feb 22, 2022 5:07 pm Don't count on any of those going that low, by about an octave. The only musical instruments capable of that are the largest pipe organs.

All of them do in fact go as low as their titles claim. They're all "re-bassed", remixed with pitch matched sinewaves added in. They're not all great renditions of the original content. But, they should showcase the capabilities of a THT pretty well without having to play short movie tracks over and over and over. Might wanna order some museum putty for all your nick knacks though.