I've finally come across a pair of these at a price I could afford. I've drawn the crossover out to the best of my ability. Can someone explain the woofer's crossover and why it has 3 inductors? It seems the tweeter has a simple resistor to lower the level, and a 6.8uF cap to block low frequencies.
The drive units are Vifa units. XT25TG30-04 for the tweeter & P17SJ-00 008 as the woofer. Nice sounding speakers, perhaps a little bright, I find it interesting that the resistor I've labeled R2 is 4.7Ω and 3.9Ω on the other crossover. Is this how they dial everything in to be exact and get them as matched pairs?
Thanks,
Nick
The drive units are Vifa units. XT25TG30-04 for the tweeter & P17SJ-00 008 as the woofer. Nice sounding speakers, perhaps a little bright, I find it interesting that the resistor I've labeled R2 is 4.7Ω and 3.9Ω on the other crossover. Is this how they dial everything in to be exact and get them as matched pairs?
Thanks,
Nick
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Congrats, that is one cool looking speaker!!
I have never heard it but been a fan of the look ever since I read about it in stereophile in 2003.
Earthworks Sigma 6.2 loudspeaker | Stereophile.com
I have the drivers on the shelf, and I think the midwoofer is more like midrange, not much bass can come out. Can you tell some about the interior, about the damping.
Crossover is a first order circuit with two response corrections on the midwoofer.
I am glad to see your pics, thank you!
I have never heard it but been a fan of the look ever since I read about it in stereophile in 2003.
Earthworks Sigma 6.2 loudspeaker | Stereophile.com
I have the drivers on the shelf, and I think the midwoofer is more like midrange, not much bass can come out. Can you tell some about the interior, about the damping.
Crossover is a first order circuit with two response corrections on the midwoofer.
I am glad to see your pics, thank you!
That particluar LCR is just an impedance equalizer.
See the effect with it in circuit ( red line at bottom ) or out.
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It's a bit of a unique circuit ( so thanks for bringing forward ).
The other LCR ( bypassing L1 ) acts as a PEQ with a bit of boost ( centered around 4200 hz ) which is the frequency area where JohnA ( of Stereophile fame ) mentioned there is measurable off-axis "bloom" .
Anyways, with both drivers set for positive polarity I need to add 1/2" of offset depth to the tweeter to get the hi-mids ( above 1K ) to break the 85db thresh-hold .
OTOH, if I flip the tweeters polarity ( and go back to zero offset I get the following;
The peakiness seen at around 8K ( now ) more closely resembles Stereophiles measurements ( I think ).
Makes me wonder, what's going on here.
The other LCR ( bypassing L1 ) acts as a PEQ with a bit of boost ( centered around 4200 hz ) which is the frequency area where JohnA ( of Stereophile fame ) mentioned there is measurable off-axis "bloom" .
Anyways, with both drivers set for positive polarity I need to add 1/2" of offset depth to the tweeter to get the hi-mids ( above 1K ) to break the 85db thresh-hold .
OTOH, if I flip the tweeters polarity ( and go back to zero offset I get the following;
The peakiness seen at around 8K ( now ) more closely resembles Stereophiles measurements ( I think ).
Makes me wonder, what's going on here.
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Your drawings are accurate, you haven't made any mistakes.
I mentioned in my first two posts what the 2 LCR circuits do ( one is an impedance EQ, that flattens the overall load, which is accomplished by the 1mH coil that's in series with the 15uF cap and the 10 ohm resistor ) while the other provides a bit of lowQ FR boost ( for the woofer ) centered around 4200hz ( that's the LCR comprisings parts values of 0.47mH, 3.3uF + 39R ).
The other components ( "my" schematics L1 & C1 < or > 1mH & 6.8uF ) form a 6db per octave crossover that's centered around 3K.
The 4.7R resistor found in front of C1 attenuates the tweeter level to better match the woofer.
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Just some more photos showing the cabinet and the construction. Threaded metal inserts are used to secure the back panel on. The P17SJ-00s were broken in, measured and "matched" No labels on the tweeters, but they seem to replace them with XT25TG30-04 and they sound identical. Binding Posts are WBT 0765 (fully insulated) apparently they are $40 each
I bought a Hafler XL-600 from a guy who worked there, and as such, I was shown around the place (they have measurement rooms and lots of fancy stuff) and that's when I heard these speakers for the first time. They had a bunch of Denmark made XT25TG30-04 tweeters lying around for replacement purposes.
I've also heard from Eric Blackmer (son of the founder) and he stated the cabinets were a real chore to produce. They had to send a lot of cabinets back due to defects. The difficulty of production and the discontinuation of the P17SJ/P17WJ I think is what pushed them to discontinue it (just my guess)
I bought a Hafler XL-600 from a guy who worked there, and as such, I was shown around the place (they have measurement rooms and lots of fancy stuff) and that's when I heard these speakers for the first time. They had a bunch of Denmark made XT25TG30-04 tweeters lying around for replacement purposes.
I've also heard from Eric Blackmer (son of the founder) and he stated the cabinets were a real chore to produce. They had to send a lot of cabinets back due to defects. The difficulty of production and the discontinuation of the P17SJ/P17WJ I think is what pushed them to discontinue it (just my guess)
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