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Old 12th September 2012, 09:34 AM   #311
AndrewT is offline AndrewT  Scotland
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Quote:
Originally Posted by atupi View Post
I will try also to change the termal paste to a more advanced one .......
As a temporary measure, use oil.
Anything that fills the gaps and excludes the air is good enough to prove the heatsink is big enough.

Oil will allow metal to metal contact. You can't get a thinner interface than metal to metal.
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Old 12th September 2012, 10:12 AM   #312
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Quote:
Originally Posted by AndrewT View Post
This is a return to the paint affecting the parasitics.
Sorry, no.

Those caps are rolled, so they've an outer foil, so a preferred direction.

On smaller KP1834 outerfoil is indicated (by ERO, the manifacturer) with a yellow paint dot, on bigger ones by markings.
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Old 12th September 2012, 10:37 AM   #313
bcmbob is offline bcmbob  United States
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atupi, when you remove the heatsink can you see a full footprint from the LM3886? This is what happens when a bit of old compound residue remains between the chip and the heatsink. Do you have any means to measure the temperature other than touching?
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Old 12th September 2012, 08:16 PM   #314
atupi is offline atupi  Romania
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I have changed today the C32-150pf cap from Amtrans to NOS polistirene recommended by DArio and the difference was amazing even more noticeable than rolling different caps in C7 position.
For C9 i played around with BG PK and Nichicon Finegold and i'm not decided yet. Nichicon sound a bit fuller that BG wich is very detailed but i'm not decided yet.
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Old 12th September 2012, 10:31 PM   #315
bcmbob is offline bcmbob  United States
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Beta build is operational again.

Component mix: ApexJr 120 VA toroids, M-Cap Zn, Black Gate STD, C101/201 Generics, Amtrans, Caddocks and Renkins. Still sounds great and very close to the premium RC build. I'll do a little more swapping and twirling and then remove all sockets for a final solid build.
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Old 14th September 2012, 01:14 PM   #316
romvise is offline romvise  Italy
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Hi Bob, can you explain me more accurately what difference you listen between 120VA and 300VA toroids trasformer? Does it sound more louder, or it's just more solid with 300VA?
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Old 14th September 2012, 01:53 PM   #317
bcmbob is offline bcmbob  United States
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Yes, the full impression is louder by about 10- 12% - not a big bump up. What is more significant is the sense of reserve power or headroom. All amps I've heard have a point when it sounds like they are struggling to keep up. The larger transformer moves that point farther away/up the volume scale. Remember this is closely related to the size and efficiency of the speakers being driven. Bookshelf speakers might be just fine with smaller transformers.

The low end is both augmented and better controlled - particularly when combined with the Mundorf AG caps , but that improvement actually extends well into the mid frequencies. I'm not sorry I bought the "Big Daddys" but anything between 125 and 200 would have been completely adequate. I get the impression from Dario that R-cores push a bit more power per transformer rating. That might be something to take into consideration.
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Last edited by bcmbob; 14th September 2012 at 01:56 PM.
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Old 14th September 2012, 10:50 PM   #318
romvise is offline romvise  Italy
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Thanks a lot. Now I'm using two 160VA from my GC, so I'll wait to end other project (about room's acoustic) and I'll evaluate an upgrade toroidal or r-core.
I've also read, Dario experience with r-core and what is striking is the difference in efficiency: 120VA for r-core and at least 250VA for toroid!

Roberto
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Old 17th September 2012, 09:22 PM   #319
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Default CapXon - Courtesy of Soongsc

I have finished my evaluation of the CapXon 220uF non-polarized cap in C9 position. I made several evaluations in hopes of not fooling myself. My main comparison cap was the BlackGate PK which has been my early favorite.

Overall, I found the CapXon NP to be equal to the BG PK, but a little different. The image between the two was very similar, but the CapXon seemed to have slightly more detail. In contrast, the BG PK had slightly more bass and bit rounder sound. The choice between the two would depend on your taste and your system, but they are both very nice sounding caps. I am especially happy that Soongsc found the CapXon because it is a good alterantive and they aren't making BlackGates anymore.

Jac
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Old 17th September 2012, 10:24 PM   #320
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Interesting... Which voltage rating was the CapXon?

Inviato dal mio LT22i con Tapatalk 2
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