Um, I never ever said anything like that. I said going from film to film was less risky.
+1 Lojzek, direct measurement is the way to go.
Best,
E
Hi, Eric
Apologies for not clarifying that the original Kef design used Bennic/Kef/Alcap BP electrolytics. The xovers were worked over and mostly MKPs fitted. The speakers sound like the tweeters are shot, although they aren't. Like you said it's probably to do with C3 and C4.
I downloaded the test tones and will run them tomorrow.
All the best
Hi, Eric and Lojzek.
I measured 0.70V to 0.72V at the HF and LF terminals for all the tests.
The upside is I am saving a fortune on utility bills...
The Kef Q60 specs are attached for reference. Grateful for your advice.
All the best.
I see those are ferrofluid cooled tweeters. Maybe the oil has dried out? Maybe the tweeters are physically damaged. We've certainly had people waste a huge amount of time on upgrading the crossover where the problem is elsewhere.
One of the few interesting and useful measurements of capacitor quality I have ever seen below. Hysteresis is essentially what you get with a non-linear lossy system, IIRC. Of course the actual drivers and inductors are less than perfect too, so a balanced approach is in order, IMO.
One of the few interesting and useful measurements of capacitor quality I have ever seen below. Hysteresis is essentially what you get with a non-linear lossy system, IIRC. Of course the actual drivers and inductors are less than perfect too, so a balanced approach is in order, IMO.
Attachments
Hi, Steve.
Many thanks for your time and expertise.
The speakers are 24 YOA, so I guess it's time to replace the ferrofluid. The ferrofluid sold at Good Hifi VOF NL is formulated specially for speakers.
Best regards,
Hi, Steve.
Finished the crossovers and replaced the ferrofluid with the Good Hifi VOF product. The glue KEF used to attach the coil in one of the tweeters had degraded and the coil was loose. I glued it again with Bostik Glue&Fix.
The speakers sound great again.
Voltages improved to 1.091 VAC (left speaker - both terminals) and 1.154 VAC (right speaker - both terminals).
All the best.
Audio "Noise" in Resistor ONLY when passing DC?
Reverting back to the OP, do we all agree that resistor "noise" only becomes an audio factor when said resistor is passing DC?
On that basis then, replacing the sand cast resistor in the crossover of my speaker is pointless, as it is never likely to pass DC?
I understood that this was an accepted fact.
Are we in agreement on this? Or is this subjective?
Not looking for a fight; just trying to understand, so I can make the right moves on my next project...
Thoughts from the experts?
Reverting back to the OP, do we all agree that resistor "noise" only becomes an audio factor when said resistor is passing DC?
On that basis then, replacing the sand cast resistor in the crossover of my speaker is pointless, as it is never likely to pass DC?
I understood that this was an accepted fact.
Are we in agreement on this? Or is this subjective?
Not looking for a fight; just trying to understand, so I can make the right moves on my next project...
Thoughts from the experts?
What about power dissipation?
On several occasions, I've come across (installed) resistors that vary in condition anywhere from toasted looking to open-circuit to physically destroyed; yes - that includes sand-cast ones in passive speaker crossovers. (I don't understand how this is even possible - I'd think the HF driver coil should succumb far before a power resistor! By the same token, how do the wire-wound potentiometers in the same crossovers survive that abuse?)
My standard "go-to" for power resistors has been the type with (typically gold anodized) ribbed aluminum shell and mounting tabs. These are cheap enough to order online, and available in relatively large power ratings. Properly mounting them to a heat-sinking surface is - I believe - necessary to achieve their rated dissipation.
Oh: I'd be happy to hear from the experts as to whether said resistors are commonly counterfeited like we've learned about semiconductors & capacitors - I have yet to find one that measures outside of it's specified tolerance; or whether they might have any characteristics that would make them undesireable for audio signals.
On several occasions, I've come across (installed) resistors that vary in condition anywhere from toasted looking to open-circuit to physically destroyed; yes - that includes sand-cast ones in passive speaker crossovers. (I don't understand how this is even possible - I'd think the HF driver coil should succumb far before a power resistor! By the same token, how do the wire-wound potentiometers in the same crossovers survive that abuse?)
My standard "go-to" for power resistors has been the type with (typically gold anodized) ribbed aluminum shell and mounting tabs. These are cheap enough to order online, and available in relatively large power ratings. Properly mounting them to a heat-sinking surface is - I believe - necessary to achieve their rated dissipation.
Oh: I'd be happy to hear from the experts as to whether said resistors are commonly counterfeited like we've learned about semiconductors & capacitors - I have yet to find one that measures outside of it's specified tolerance; or whether they might have any characteristics that would make them undesireable for audio signals.
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