Help with Vintage Woofer

[GM]

Here's the SPL curve I'm getting with 5 watts in a 2.5L enclosure: https://www.screencast.com/t/2LVAht8WyI

Based on the other dims, this s/b ~2.5 ft^3 and using an effective piston dia. = ~12.95", Hornresp shows a somewhat more under-damped alignment of ~1.0 Qtc with ~15 W required to get 100 dB/m in 2pi [half] space, so wondering if with your program apparently being for mobile audio it's automatically adding a 'cabin gain' EQ curve.

Regardless, this driver 'wants' around 150 L [~5.3 ft^3 net] and ~25 W for a 100 dB/m down to 20 Hz in 2pi space, so on the floor in a corner to reduce this to 5 W. If you're really only interested in down to 30 Hz, then 2.5 ft^3 is OK in a corner, just might not sound 'tight'/'fast' enough, though heavily stuffing it will help.

GM

 

[GM]

Thanks @GM.

You're welcome!

Agreed, long ago I ran dual Altec 515B in huge false wall IBs where power handling was next to nothing, but so efficient it didn't matter. The 'little' JBL OTOH isn't nearly as large/efficient, so care must be taken to not overdrive them too much. As a general rule, if you can see low Xmax drivers move from the listening position you're real close to/at the limit.

GM

 

[system7]

I'm getting confused here.

DCS3854 15" Classic Subwoofer 4 Ohm:

https://www.parts-express.com/pedocs/specs/295-206-dayton-audio-dcs385-4-specifications-46581.pdf

Vas 311L. Qts= 0.39. I can do the math. That's about 150L for flat closed Qc= 0.7 box, isn't it?

The JBL L123A is Qts= 0.55, Vas= 183L according to Troels. And about 90dB, FWIW.
JBL L100 Century
Not a reflex candidate really, unless you like lumpy bass.

He actually fancies aperiodic in a manageable enclosure size. JBL L100 Century,

And surely that doesn't need a subwoofer, unless you live in an aircraft hanger.

 

[maLx]

I'm getting confused here.

DCS3854 15" Classic Subwoofer 4 Ohm:

https://www.parts-express.com/pedocs/specs/295-206-dayton-audio-dcs385-4-specifications-46581.pdf

Vas 311L. Qts= 0.39. I can do the math. That's about 150L for flat closed Qc= 0.7 box, isn't it?

The JBL L123A is Qts= 0.55, Vas= 183L according to Troels. And about 90dB, FWIW.
JBL L100 Century
Not a reflex candidate really, unless you like lumpy bass.

He actually fancies aperiodic in a manageable enclosure size. JBL L100 Century,

And surely that doesn't need a subwoofer, unless you live in an aircraft hanger.

I'm cutting the JBL woofers off at 160 and up because I want to design an OB speaker and the room is too small for baffles with waves lower than that. That's why I'm adding a sub.

 

[maLx]

Based on the other dims, this s/b ~2.5 ft^3 and using an effective piston dia. = ~12.95", Hornresp shows a somewhat more under-damped alignment of ~1.0 Qtc with ~15 W required to get 100 dB/m in 2pi [half] space, so wondering if with your program apparently being for mobile audio it's automatically adding a 'cabin gain' EQ curve.

Regardless, this driver 'wants' around 150 L [~5.3 ft^3 net] and ~25 W for a 100 dB/m down to 20 Hz in 2pi space, so on the floor in a corner to reduce this to 5 W. If you're really only interested in down to 30 Hz, then 2.5 ft^3 is OK in a corner, just might not sound 'tight'/'fast' enough, though heavily stuffing it will help.

GM

Ah you might be right. Can you send me the Hornresp file you made so I can open it and take a look? I'll try configuring it there.

 

[maLx]

@GM the reason I ask is because I don't know how to use Hornsrep so I'm hoping seeing your file will help. <3

 

[GM]

Vas 311L. Qts= 0.39. I can do the math. That's about 150L for flat closed Qc= 0.7 box, isn't it?

So HR predicts, hence my oblique way of saying it 'wants' around 150 L....

GM

 

[GM]

Ah you might be right. Can you send me the Hornresp file you made so I can open it and take a look? I'll try configuring it there.

No Problemo, was going to until I saw you are using a $249 program that at a glance apparently can be matched/bested with a few freeware programs.......

Regardless, you can ask Qs here and/or browse/ask on the designer's massive HR thread: Hornresp

GM

 

[maLx]

No Problemo, was going to until I saw you are using a $249 program that at a glance apparently can be matched/bested with a few freeware programs.......

Regardless, you can ask Qs here and/or browse/ask on the designer's massive HR thread: Hornresp

GM

No problem! You live and you learn. It is possible I'm just using the program wrong. I'll give them a call later this week and ask! Now, onto figuring out how to open these files.

Did you say by your calculations I'm looking at a 150L box? So around 5f^3?

 

[maLx]

@GM this driver might do better. B&C 15NW100 15" Neodymium Subwoofer Speaker Driver

I'm getting this SPL at 70L. https://www.screencast.com/t/QsS4nnrXOK1k
Here are my input parameters: https://www.screencast.com/t/XA4LiXLD

What can I change here or play with to get a flatter response between 30-160hz? Also is that SPL at 1w/1m?

Also on calculate, what do you say to this message? https://www.screencast.com/t/nbueurHDvDoL

Thanks for your help!

 

[GM]

The only obvious error was the piston diameter, which in retrospect would account for much/all of the discrepancy, so just change it before comparing to HR. Note too that the 1.0 Qtc is a typo, should be ~0.92 Qtc Vs TermCad's 0.906 Qtc.

Re finding effective piston diameter, specs normally are area in cm^2 [Sd], so [Sd*4/pi]^0.5 to get its diameter in cm, then of course cm/2.54 for inches.

Well, the default standard box alignment is a max flat one or ~150 L for the DCS, i.e. any other tuning results in a higher roll off [less bass], but often isn't ideal in room since down low the room's acoustics dominate.

Anyway, once the program is loaded, then download the two files to HR's IMPORT Folder, then in the program: FILE/IMPORT/HORNRESP RECORD to see the files, then double click on one to auto load it and then do the other, then click on ADD to SAVE and make new files to tweak/whatever.

GM

 

[maLx]

Cool thanks, so I opened the second file with the QTC of 0.9 and manipulated the box and also changed the power rating to 10w at 8ohm instead of 1. I get this: https://www.screencast.com/t/24KkbHhrGrJV

Does it look right?

I'm +5dB from 30-60hz and then it rolls down slowly. I can always EQ the sub?

Do you have any driver recommendations of a 15" sub that can get a nice flat response but fit in a relativity small cabinet?

Thanks for your help.

 

[GM]

What can I change here or play with to get a flatter response between 30-160hz? Also is that SPL at 1w/1m?

Also on calculate, what do you say to this message? https://www.screencast.com/t/nbueurHDvDoL

Thanks for your help!

With a 33 Hz Fs, it's no sub-woofer and with a low Qts it's a prosound mid-bass driver normally loaded in a compact vented alignment tuned as high as 60 Hz, so either requires a huge TL/horn to go low at high efficiency or use mass quantities of EQ to flatten it, i.e. in speaker design one is always trading efficiency for extended [flat] bandwidth [BW] in typical sealed, vented alignments.

Yes.

Folks normally put at least some damping in the cab, so normally have 'MASK' enabled.

You're welcome!

GM

 

[maLx]

Thanks GM.

Going to look at some more subwoofer driver options later this week.

 

[GM]

You're welcome!

I don't keep up with available drivers and in general am more prosound oriented and accept the [super] large cabs required.

In general, you want as much Xmax as you can afford, an Fs at/below the lowest frequency desired/likely needed to be reproduced at an audible level once room gain is factored in and for small cabs, the smaller the Vas spec combined with a Qts around 0.4 is [normally] an acceptable compromise between a ~flat in-room response and cab size.

In general then, mobile audio 'sub' woofers is where I'd look first and since low Vas, medium Qts spec drivers have abysmal efficiency, plan for needing a bit power.

GM

 

[maLx]

@GM I thought of looking at the mobile market actually since there are some great driver offerings there. I previously built a set of Satellite speaker out of some Focal drivers and they are really nice for listening for streaming/modern music as they offer a great level of detail and clarity with out too much where you hear how crappy most modern music is recorded these days.

 

[maLx]

@GM so check this out.

Using this driver: https://www.parts-express.com/pedocs/specs/295-468-dayton-audio-rss390hf-4-specifications-46176.pdf

I get this response using a volume of 132L. https://www.screencast.com/t/dg8avT43FRz4

Here's my input parameters: https://www.screencast.com/t/A9vbtJtV

I'll make a box out of 1" cherry with an inside diameter of 24x24x14 and a 1" brace somewhere.

Will need to put some solid wattage into this speaker to reach 95 ish db where the other drivers are at but what do you think?

 

[GM]

If you're happy enough with the sim and it's limited to ~ a decade [< ~200 Hz]........

Re building speakers out of real wood, it's generally not a good plan, especially for <sub>woofers, so if not already done might want to [re]search this subject before cranking up the saw.

GM</sub>

 

[maLx]

If you're happy enough with the sim and it's limited to ~ a decade [< ~200 Hz]........

Re building speakers out of real wood, it's generally not a good plan, especially for <sub>woofers, so if not already done might want to [re]search this subject before cranking up the saw.

GM</sub>

_{Yeah I know because of warping. The way to stop that is to take 1x4 boards, plane them, edge them, glue them together alternating grain, it takes a lot of time but you can get a solid piece if you do it that way.}

 

[GM]

Just checking; me, I laminated it to marine grade plywood assembled to a frame like building a shed, house.

GM