Richard Allan crossover query.

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AllenB

AllenB

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Joined 2008
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A 10 ohm pot is not the same thing as a variable L-Pad
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Indeed in the case of the constant impedance variable but they are quite similar, especially considering the amount of attenuation in this case and the utility requirement. I think it could get close enough when connected as an L-pad to give reasonable starting values and save the expense of buying a variable L-pad unit in this case.

The resulting impedance will probably be greater than 7 ohms when giving 10dB of attenuation, and should only rise toward 10ohms at infinite attenuation.
 
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H

hugo_zair

Member
Joined 2008
rogerj.co.uk
AllenB said:
Indeed in the case of the constant impedance variable but they are quite similar, especially considering the amount of attenuation in this case and the utility requirement. I think it could get close enough when connected as an L-pad to give reasonable starting values and save the expense of buying a variable L-pad unit in this case.

The resulting impedance will probably be greater than 7 ohms when giving 10dB of attenuation, and should only rise toward 10ohms at infinite attenuation.
Click to expand...

One speaker is back together and jury rigged. After reading the above i did a little ohms law and saw that with a 10ohm pot in the middle (5+5), the impedance looking back to the filter is 8.08ohms...Possibly close enough given that driver is not a resistor anyway..So I started there and did some critical (!!) listening with Queen, Genesis, Blues Bro's and Led Zep..With a test that crude I have to admit I couldn't hear a consistent difference when tweaking slightly either side, given the variations in the input matter... So unless The other speaker (which I'll start on later) is different I think I'll go with that.
with some help from an online calculator I make that -8.5 dB..The HF driver is certainly tamed...More later..Roger
 
H

hugo_zair

Member
Joined 2008
rogerj.co.uk
@ Galu and AllenB..Thanks again for your input..you have made me actually think about what I'm doing to good effect...Speaker B is also now rigged and tested and I'm dead chuffed with it at the same settings...better that spk A. The reason for that is that Eminence 15 has tighter bass than the unbranded Tapco original..The muddy upper lows of that one have gone..(wish I had another one ). The transition from bass to HF is far better and probaly better than some I've heard.
So I'm left with some boring work fitting an input panel. 5ohm R's on order.
Cheers guys..Roger edit..Ps..I went with the QTX XO's
 
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