Can anyone help me tame this 6' beast? - diyAudio
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Old 11th March 2010, 02:56 PM   #1
johnr66 is offline johnr66  United States
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Default Can anyone help me tame this 6' beast?

I finished building this TH. I am impressed with the output. It is very strong in the 32 to 37Hz range, but seems weak in the 40 to 80Hz range. There is extension down to 29Hz and very little below 27Hz. It is strong above 85Hz. I wish I could boost that middle section. I don't care about going any lower.

Could anyone model this as it is and with a better matched speaker? For now, I just used a speaker I had laying around. Note internal length should read 70-1/2"
Thanks!

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Old 11th March 2010, 04:35 PM   #2
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You haven't given all HR input-parameters. Though it seems to be a pretty uniform flare rate/expansion. S2 is in the middle of the driver, near the closed end. S3 is in the mdiddle of the driver, near the mouth.

I assume you're not in touch with HR yet, this might help: Guide to WinISD Pro and Hornresp - Speakerplans.com Forums - Page 1

You change it into a HR-record and suddenly even lazy people like me don't mind lending a hand

I think I would start with a lower Vas, lower Qes, higher Fs driver.

Best regards Johan
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Old 11th March 2010, 05:26 PM   #3
bjorno is offline bjorno  Sweden
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Quote:
Originally Posted by Rademakers View Post
..I think I would start with a lower Vas, lower Qes, higher Fs driver.

Best regards Johan..
Agree, FYI, A quick plot in HR reveals a lot:

b
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Old 11th March 2010, 09:48 PM   #4
bjorno is offline bjorno  Sweden
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Code:
Originally Posted by Rademakers:  
..I think I would start with a lower Vas, lower Qes, higher Fs driver.

Best regards Johan..
If using an imaginary not yet determined driver:

b
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Old 12th March 2010, 12:32 AM   #5
jbell is offline jbell  United States
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as others have said, that box/driver combo appears to have issues.

A pa driver would be better suited (3012lf in black, vs your driver)

If you want to keep your driver, moving baffle to 4" for throat side instead of 2" helps some, but it's still kinda ugly.
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Old 12th March 2010, 01:42 AM   #6
johnr66 is offline johnr66  United States
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Hey Guys,
Thank you much for taking the time to look at this TH for me. The modeled curves do seem a bit off from what my ears hear. My function generator reads 33-35Hz when the output is strongest, about 10Hz lower than modeled. The speaker is 20 years old and the foam is about to go, so that might be the reason.

Edit: After more listening, the peak does seem to be at 39-40Hz. Wish I had real testing gear.

I pulled a driver out of another speaker and tried it Fs: 26, Qes .31, Vas 8 Cu/ft. Not ideal, but worth a test. It has better extension into the upper 20Hz range and sounds louder in the 40 Hz range. It still has dead zones. It certainly illustrates how driver parameters affect the horn response.

I can't read the data from the HR runs.

Last edited by johnr66; 12th March 2010 at 02:07 AM.
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Old 12th March 2010, 04:56 AM   #7
GM is offline GM  United States
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Open them in a new tab, then if you still can't read them, use the CTL and + keys to continue to enlarge it.

GM
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Old 12th March 2010, 06:01 PM   #8
johnr66 is offline johnr66  United States
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What do you think of this one? Will I lose my sub 30 Hz extension with this PA speaker? It is from Parts Express. I live nearby and can return it to them if I'm not happy, so I'd rather buy through them. This is under $100 and in my price range. Only problem is I can't find any low Qes drivers in my range.

Performance optimized for sound reinforcement systems. Also suitable for lead and bass guitar, keyboards, guitar combos club music systems and stage monitors. Specifications: *Power handling: 250 watts RMS *VCdia: 2" *Le: 0.64 mH *Impedance: 8 ohms *Re: 5.0 ohms *Frequency range: 43-3,800 Hz *Magnet weight: 38 oz. *Fs: 47 Hz *SPL: 98 dB 1W/1m *Vas: 4.2 cu. ft. *Qms: 6.00 *Qes: 0.50 *Qts: 0.46 *Xmax: 4.4 mm *Dimensions: Overall Diameter: 12.03", Cutout Diameter: 10.95", Mounting Depth: 4.57".
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Old 12th March 2010, 07:24 PM   #9
bjorno is offline bjorno  Sweden
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Quote:
Originally Posted by johnr66 View Post
What do you think of this one?..

Specifications: *Power handling: 250 watts RMS *VCdia: 2" *Le: 0.64 mH *Impedance: 8 ohms *Re: 5.0 ohms *Frequency range: 43-3,800 Hz *Magnet weight: 38 oz. *Fs: 47 Hz *SPL: 98 dB 1W/1m *Vas: 4.2 cu. ft. *Qms: 6.00 *Qes: 0.50 *Qts: 0.46 *Xmax: 4.4 mm *Dimensions: Overall Diameter: 12.03", Cutout Diameter: 10.95", Mounting Depth: 4.57"..
Hi Johnr66,

Sorry, The data given here above is not consistent. Please submitt the brand name and/or usually a pdf specification sheet.

To scale within reason suitable T/S data I provided to match your enclosure:
Use the built in driver select wizard in HR: see the picture where the B&C 12HPL76 12 was found to be a good match.

Parts-Express.com:B&C 12HPL76 12" Neodymium Woofer | bass midbass bass mid neo lightweight DOTW_091509


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Old 12th March 2010, 07:50 PM   #10
johnr66 is offline johnr66  United States
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Thanks bjorno. That speaker is a good match, but too expensive for me. Anything in the sub $100 range that would work reasonable?

Here is the PDF for the other speaker.
Thanks, John
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