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Old 28th October 2012, 06:17 PM   #581
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Default Capacitor Auditions, Redux

After having to take a few days out for normal life, I'm back to listening to capacitors in C13. I really enjoyed Tom and Andrew's discussion about brightness and clarity. In there own ways, both match the way I've been thinking about it, but with a way better explanation than I could have come up with.

Dario reminded me that I needed to check orientation. To be honest, I hadn't thought to do that, although I should have. As always happens, I managed to pick the wrong orientation for both the ZN and the True Copper. Of course, I had the right orientation for the K71, so I am batting 1000.

With the orientation of the True Copper switched, I understand what Tom and everyone have been talking about. The front to rear soundstage has improved and the clarity (as defined earlier by Tom and Andrew) improved. I could hear higher harmonics of strings and the size of the recording room more clearly without becoming hissy or harsh. I have the impression that the mid range is more forward and the overall sound is warmer. The bass is still amplified in my system, but this is more comfortable when there is not so much contrast to the mid range.

Listening again to the K71, they are still a touch cool in my system and the TC are now warmer. The K71 also have a lot of clarity and they have an equal or slightly better soundstage depth than the TC in the switched orientation. Overall, the K71 still sound very natural in my system, if a bit cool.

The switched orientation ZN are still forward in the mid range, but they have improved clarity and image. They feel more balanced than before and still very smooth and liquid. Wow, the choices just get tougher.

In the end, both the TC and K71 beat the ZN for clarity and image in my system. I think that, like Tom, the TC bass issue may disappear when I crossover the satellites as I believe the bass amplification is mainly below 100 Hz. That leaves me with a choice between cool and warm. I'll do some extended listening to the TCs before sending them back to Bob and decide what to order.

Jac
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Old 28th October 2012, 06:20 PM   #582
Marra is offline Marra  United Kingdom
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Thanks for the good wishes.I haven't had chance to check things as I'd hoped but seem to remember that the voltage across the diode was something like 14/15v on the good board;its certainly one of the things to check.
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Old 28th October 2012, 06:23 PM   #583
Bill_P is offline Bill_P  United States
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One relay sample measured: 14.7 volts was needed to pick the relay and it dropped out at 4.1 volts.

R14 (470 Ohms) will reduce the steady state DC voltage to the relay and its driver circuit. I reduced the resistor to 68 Ohms in my RefC amplifier to get 24 volts.
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Old 28th October 2012, 07:58 PM   #584
AndrewT is offline AndrewT  Scotland
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add in the snap action capacitor.
It builds up a higher voltage before the driver transistor conducts. Then when the transistor does conduct the relay coil sees the higher capacitor voltage for a few tens of milliseconds and that "snap action" occurs. After that short period of enhanced current availability, the cap has discharged down to the standing voltage available long term from the PSU and the relay holds in without consuming extra current/power.

This was all described in the earlier Threads and in a few other non related Threads. All it costs is a 22uF to 47uF 35V capacitor. It ensures correct triggering of the relay.
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Old 28th October 2012, 09:38 PM   #585
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Quote:
Originally Posted by AndrewT View Post
add in the snap action capacitor.
It builds up a higher voltage before the driver transistor conducts. Then when the transistor does conduct the relay coil sees the higher capacitor voltage for a few tens of milliseconds and that "snap action" occurs. After that short period of enhanced current availability, the cap has discharged down to the standing voltage available long term from the PSU and the relay holds in without consuming extra current/power.

This was all described in the earlier Threads and in a few other non related Threads. All it costs is a 22uF to 47uF 35V capacitor. It ensures correct triggering of the relay.
Andrew,

Very interesting. I search for "snap action capacitor" without results. Where are the putting the capacitor? Can you explain a bit more?

Thanks

Jac
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Old 28th October 2012, 10:28 PM   #586
bcmbob is offline bcmbob  United States
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Quote:
Originally Posted by lehmanhill View Post
Wow, the choices just get tougher.

I'll do some extended listening to the TCs before sending them back to Bob and decide what to order.

Jac
AMEN !!

Take all the time you need, cause if you have the caps I get a few weeks of relative sanity.

If you have it, run the Isotek process multiple times. I often start it in repeat mode and leave the house to do errands. For me, after about 4 half hour sessions there isn't much obvious change - - though I believe the system will continue to sweeten over additional weeks and months.
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Old 29th October 2012, 08:19 AM   #587
AndrewT is offline AndrewT  Scotland
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find the transistor and relay coil traces.
You need the cap to span across both the coil AND the transistor.
While the transistor CE is open circuit the cap charges at the RC rate set by the cap value and the preceding resistor/s. When the transistor CE becomes closed (high Ib makes the CE appear as a short circuit) the cap discharges through the coil.

I did not call it a snap action previously. Just a term that came into my head this time around.

I told Salas about the bad design of the relay driver. He would not take any action to correct the reliability of triggering fault.
I told Freman he had adopted a bad design even though I had previously posted a few times why it was a bad design. He too did not take action.

I repeatedly see problems reported on reliability of triggering.
It could have all been avoided if the original circuit had been thought about.
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Old 29th October 2012, 08:50 AM   #588
bcmbob is offline bcmbob  United States
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It would be interesting to determine if those builders with this problem ordered the BOM verbatim from Mouser or another supplier. I have always thought it is well worth the cost of a few extra dollars to start with an "as published" BOM. That approach has given a 4 for 4 successful initial power-up in my builds.

I'm still curious about what swapping the two relays would produce.
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Last edited by bcmbob; 29th October 2012 at 08:54 AM.
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Old 29th October 2012, 09:01 AM   #589
AndrewT is offline AndrewT  Scotland
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A 24V relay normally expects to be triggered with and run on near 24V.
It's the driver circuit that has trouble in getting that 24V to the relay.
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Old 29th October 2012, 09:33 AM   #590
bcmbob is offline bcmbob  United States
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Andrew, Could you provide a drawing/schematic for what you are proposing? There is still the possibility (I think) of adjustments to the final version board if a tangible benefit is the result.
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