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Multi-Way Conventional loudspeakers with crossovers

Spendor S100 crossover question
Spendor S100 crossover question
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Old 10th July 2019, 01:27 PM   #1
ref3a is offline ref3a
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Default Spendor S100 crossover question

Hello dears,
thsi is my first post, and first of all please accept my apologizes for my poor english
I own Spendor S100 which seem to work fine. Woofres, midranges and tweeters work. Yesterday, just for couriosity, I took some measerements with a simple digital tester. While testing, the spekers were obviously disconnected from the amplifier
I try to test the continuty between + and - binding post, there is no continuity for the tweeters nor for the midranges, while woofers only show continuity. If I try to read impedance between + and - binding posts, the result is the same: no value for tweeter and midranges. Woofers show impedance of 7.8 ohm.
So I opened the back of the speakers to read impedance at the OUT side of crossovers. Here both tweeters shows 5.8 ohm both midranges 1.8 ohm (woofers show again 7.8 ohm). I have almost no technical knowledge, but I think that values taken measuring at the out side are not those seen by the amplifier

Is this behavoiur normal? Are values correct?
Please help me understand :-)


I attach a picture to help me better explain



Thank you so much
Mauro - Turin - Italy
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File Type: jpg crossover s100.jpg (668.3 KB, 92 views)
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Old 10th July 2019, 03:55 PM   #2
boswald is offline boswald  United States
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Spendor S100 crossover question
Your multimeter is measuring resistance to direct current.
Speakers and crossovers work on alternate current.
Capacitors will not pass direct current.
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Old 10th July 2019, 04:53 PM   #3
ref3a is offline ref3a
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Oh... that is clear now
And then, also the values I read at the output are somehow corrupted?
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Old 11th July 2019, 07:37 PM   #4
Vrystaat is offline Vrystaat  South Africa
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I see bipolar caps there, so I assume that they may dry out over time. I have a pair of those Spendors as well, I would want to check those caps after all these years. Would those be low ESR caps when new ?They are bipolar as I see . My speakers seems to short some of the high frequencies. Bought them second hand and do not know how the have been handled
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Jan
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Old 11th July 2019, 07:47 PM   #5
Vrystaat is offline Vrystaat  South Africa
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Would this be an acceptable replacement. Capacity and volts the same.
TVA1305.5-E3 | Vishay 20μF 50V dc Aluminium Electrolytic Capacitor, Through Hole 6.35 (Dia.) x 17.45mm +85degC 6.35mm 17.45mm | RS Components
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Old 11th July 2019, 10:15 PM   #6
Galu is offline Galu  Scotland
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Welcome to the forum!

To measure the dc resistance of the various drivers with a multimeter you must disconnect them from the crossover. Remember that the dc resistance of a driver will be less than its nominal impedance.

You say your speakers are working fine, so I would leave well enough alone.

They say that curiosity killed the cat!

P.S. I should emphasise that your 'digital tester' measures the dc resistance of the driver and not its impedance (opposition to ac).

Last edited by Galu; 11th July 2019 at 10:20 PM. Reason: Added the P.S.
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Old 12th July 2019, 12:40 AM   #7
AllenB is offline AllenB  Australia
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Quote:
Originally Posted by ref3a View Post
values I read at the output are somehow corrupted?
Your meter has no idea how to interpret how it will work with an audio signal, so yes, what you measure won't be meaningful.
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Old 12th July 2019, 05:49 AM   #8
ref3a is offline ref3a
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Quote:
Originally Posted by Vrystaat View Post
I see bipolar caps there, so I assume that they may dry out over time. I have a pair of those Spendors as well, I would want to check those caps after all these years. Would those be low ESR caps when new ?They are bipolar as I see . My speakers seems to short some of the high frequencies. Bought them second hand and do not know how the have been handled
Hi
Those Bennic bipolar caps are in the woofer section
I too bought my S100 second hand (previous owner was the original first one) some years ago and I wrote Spendor asking about ageing of crossover components: they kindly replied that caps in this apllication are not stressed and they'd last forever
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Old 12th July 2019, 05:50 AM   #9
ref3a is offline ref3a
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Thank you all for yr kind replies
Mauro
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Old 12th July 2019, 07:03 AM   #10
Vrystaat is offline Vrystaat  South Africa
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Thanks guy's.
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Jan

Last edited by Vrystaat; 12th July 2019 at 07:26 AM.
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