I recently took apart some Tannoy loudspeakers and, thinking of re-using the woofer, I measured the impedance (or at least the DC resistance) at 10 ohm.
Is this likely to be a 10 or even 12 ohm woofer? Seems very unusual.
It was twinned as part of a 2 way with a DC / Coaxial driver.. The latter being a 4 ohm tweeter and another 10(?) ohm woofer... likely wired in parallel to half this impedance
Didn't rate the SQ of the DC unit so I wanted to throw a small 2 way together, twinning the woofer with a conventional soft dome tweeter. But at 10 ohm is this woofer suitable for non-paralleled operation?
Speaker in question:
VX 5.2 | 5" Dual Concentric Full Range Loudspeaker with Low Frequency Driver for Portable and Installation Application | Tannoy/TGI North America, Inc. | American Amplifier and Television
Is this likely to be a 10 or even 12 ohm woofer? Seems very unusual.
It was twinned as part of a 2 way with a DC / Coaxial driver.. The latter being a 4 ohm tweeter and another 10(?) ohm woofer... likely wired in parallel to half this impedance
Didn't rate the SQ of the DC unit so I wanted to throw a small 2 way together, twinning the woofer with a conventional soft dome tweeter. But at 10 ohm is this woofer suitable for non-paralleled operation?
Speaker in question:
VX 5.2 | 5" Dual Concentric Full Range Loudspeaker with Low Frequency Driver for Portable and Installation Application | Tannoy/TGI North America, Inc. | American Amplifier and Television
The 10 ohms you measured is refered to as RE. Now things get a little interesting as the impedience of the driver is usually a lot higher. For example for a lot of the pro JBL drivers a 16 ohm driver ofton has a DC resistance of about 8 ohms and there 8 ohm drivers may measure ~ 5 ohms. Now there are some exceptions to this but in your case it would probably be called a 16 ohm driver. As an example look at this link where you can see this Seas 8 ohm driver has a DC resistance of 6.2 ohms. Seas H1471 (CA22RNY) 8" Paper Cone
Plus a small detail; the *screen* shows the "number" 10 ... that does not mean you are measuring exactly that.
Even quite precise meters show an important error at very low resistance values, because they are also measuring the range and scale switch, test wires,test probes and banana jacks resistance together with the speaker voice coil.
All small resuistance, but add up, so you must touch test probes to each other, screen will NOT show zero but a low value, typically between 0.7 ohms and up to 1.8 ohms.
You must substract that number from what the screen shows.
Say a speaker "measures" 7.5 ohms , shows 0.8 ohms residual resistance, actual value measured is 6.7 ohms and impedance is nominal 8 ohms.
Even quite precise meters show an important error at very low resistance values, because they are also measuring the range and scale switch, test wires,test probes and banana jacks resistance together with the speaker voice coil.
All small resuistance, but add up, so you must touch test probes to each other, screen will NOT show zero but a low value, typically between 0.7 ohms and up to 1.8 ohms.
You must substract that number from what the screen shows.
Say a speaker "measures" 7.5 ohms , shows 0.8 ohms residual resistance, actual value measured is 6.7 ohms and impedance is nominal 8 ohms.
Thanks for the info.
Best to bring the Dc driver back into play then? To bring the Z back into the 8 ohm range.
I loved my old DMT Tannoy monitors, but the treble on these smaller DC drivers sounds really ragged!
Maybe I can re-couple the drivers but add a tweeter at 5khz and make it a 3 way ...
Best to bring the Dc driver back into play then? To bring the Z back into the 8 ohm range.
I loved my old DMT Tannoy monitors, but the treble on these smaller DC drivers sounds really ragged!
Maybe I can re-couple the drivers but add a tweeter at 5khz and make it a 3 way ...
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