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Old 7th October 2009, 03:46 AM   #5101
jleaman is offline jleaman  Belgium
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Quote:
Originally Posted by thanh1973 View Post
Two Pack Epoxy
no work, NOT GOOD EITHER!
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Old 7th October 2009, 05:11 AM   #5102
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Have you tried it?
This is what all the manufacturers use.

If you want better then polyurea or polyurethane would be better. If you want to improve on that then fill it with very dense pigments.
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Old 7th October 2009, 07:47 AM   #5103
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I have poted one into an aluminium pan using silicone. That made it silent but i do not know about the long time.
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Old 7th October 2009, 08:58 AM   #5104
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Silicone has some nice properties, as good as or possibly better than polyurethane
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Old 7th October 2009, 09:09 AM   #5105
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Heat sinking might be an issue?
It coud become a torrid transformer.
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Old 7th October 2009, 09:13 AM   #5106
AuroraB is offline AuroraB  Norway
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For potting a transformer, use the special compounds developed for potting- available from most professional parts suppliers, an nusually not more expensive than the amount of epoxy required.

Vacuum impregnating the core/windings of a trafo is something else - this is done with very low viscosity laquers to get into the windings. Can't be done with normal potting compounds....
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Old 7th October 2009, 02:35 PM   #5107
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Labjr: Which transformer are you using?

Hi

The Avel 250va 18v + 18v dual secondaries. It had been working fine. The same transformer in the other monoblock is working. I do have a very slight hum in that speaker, but it doesn't change when the transformer starts making the noise. Thanks for your repllies. Even with this problem the F5 is performing very nicely.
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Old 7th October 2009, 06:30 PM   #5108
labjr is offline labjr  United States
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Does one chassis buzz more than the other one if you put your ear to it?

I don't know if a noisy transformer will make a hum through the speaker. Maybe someone else can answer this.
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Old 7th October 2009, 06:43 PM   #5109
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Just the one transformer buzzes. I can hear it faintly from 3 feet away. And that unit's speaker has a very minor hum that I can only hear withmy ear on the thing and I hear it from start up. The transformer develops the buzz an hour after startup. The other monoblock makes no chassis noises and the speaker is perfectly quiet.

About this time I did do a mod on my cd player. Bypassed the output caps per Kit Ryan's .
suggested mods in Audio xpress. Could this be related? Cd is attached to B1 that is attached to F5. Thanks for help.
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Old 7th October 2009, 07:28 PM   #5110
tinitus is offline tinitus  Europe
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You could try disconnect your signal/B1, to see if it still hums
Or reverse channels from your signal/B1, to see if it follows signal
Also examine if wireing is slightly different on left/right channel

Your hum and buzz might still be two different things
Nelson have said that hum might be an indication of minor instability
And that it may be related to signal wire/grounding

As said earlier, even the slightest transformer buzzing can be "amplified" by the enclosure, and sound much worse
Without the box you might not hear anything

edit, do your supply caps get hot ?

Last edited by tinitus; 7th October 2009 at 07:35 PM.
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