Miguel Castro Rios wrote on Fri, 05 November 2010 21:13 |
Has any one built the tuba 60?? Any measurements. We are considering building a couple of them. http://www.billfitzmaurice.com/T60.html http://billfitzmaurice.info/forum/viewtopic.php?f=12&t=1 1124 We are wondering if it could replace a conventional Front Loaded. Dual 18" Sub woofer. (spl-wise) Like the EAW sb850 or SB1000. |
Art Welter wrote on Tue, 30 November 2010 21:08 |
Stipe, Nifty design, but it looks to roll off almost an octave above the Tuba 60 if this sim is accurate... |
Art Welter wrote on Tue, 30 November 2010 21:08 |
Stipe, Also important to notice for honest comparison ..spl plot for dual 12" Tuba60 (on Bill site) is done as 2,83V on 4ohm load which is 2W/1m plot not 1W/1m. According to this even smallest CB-18 is same or more efficient from 40Hz - upwards. OK, I must admit under 40Hz TUBA60 is still dominant. Best wishes, Stipe |
Stipe Ercegovic wrote on Wed, 01 December 2010 14:53 | ||
The horn's resistance usually adds a few ohms to the nominal impedance, hence the upped voltage. I don't have the T60 plans, but I'm sure this is why the measurement is done that way. |
Phil Lewandowski wrote on Fri, 03 December 2010 14:29 |
I believe Bill measures all his cabs at 2.83v to keep it consistent. So with the dual LAB12 T60 just slide the response down 2-3dB and that would be around your 1W/1M response. Take Care, Phil |
Kevin Unger wrote on Fri, 03 December 2010 18:36 | ||
Every horn of Bill's I've built has had a higher nominal impedance, Even a small 7ft horn (t39) It add to the impedance of the driver due to it having to overcome the air resistance at the horn's throat. (in a very simple explanation) I'm curious, so I'll pickup the plans. Hate to quote Bill's plans directly, but I think it won't be a problem. Here's a short from the t39 plans: "Horn loading adds the impedance of the horn air column to the driver’s nominal impedance. A single driver cab may safely be considered a 10 ohm load." |
Phil Lewandowski wrote on Fri, 03 December 2010 21:56 |
(Actually the Growler's average impedance is closer to 10 ohms as well, like with the T39. It just so happens that one of the "standards" is to pick the standard 2, 4, 8... as the nominal impedance; whichever it is closest to. So that is why a impedance plot is so helpful.) Take Care, Phil |
Kevin Unger wrote on Sat, 04 December 2010 14:06 |
Phil, an Impedance graph is included with the plans. Nominal is always stated, as it does change with frequency. |
Art Welter wrote on Sat, 06 November 2010 16:22 |
The 60 inch depth would be a problem in many venues. |
Phil Lewandowski wrote on Fri, 03 December 2010 20:56 |
I think what has really been needed for the designs is publishing a impedance plot |
Quote: |
(Actually the Growler's average impedance is closer to 10 ohms as well, like with the T39. It just so happens that one of the "standards" is to pick the standard 2, 4, 8... as the nominal impedance; whichever it is closest to. So that is why a impedance plot is so helpful.) Take Care, Phil |
Mark Coward wrote on Tue, 07 December 2010 11:59 | ||||
So there is an impedance plot for the Growler? |
Quote: |
Impedance LAB drivers have a nominal impedance of 6 ohms, but the mass of air in the horn adds about 2 ohms of acoustic impedance, giving a nominal 8 ohm load. In a 2x12 a pair of LAB 12s wired in parallel will have a nominal 4 ohm load, a pair in series a nominal 16 ohm load. |
Miguel Castro Rios wrote on Thu, 16 December 2010 12:20 | ||
I don't have a chart like the one you guys are looking for... Since I bought the plans... This is what Bill says in the plans.
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