General DIY Questions/Answers

Hello guys

Have a question about old pyramid caps. They have a yellow ring on one end...is this indication of outer leg? Working on some cap replacement for my tube amp and don't want to makea mistake...

Thanks
 

Wntrmute2

Not So Mediocre Member
Resurrecting this thread.
I'm planning a new build and have a basic question regarding the "core" of a transformer. I am ordering from Monolith Magnetics and they offer their summit line, their amorphous cores as well as their Nano-X cores.
Anyone have opinions as to the relative merits of these? There is a $75 difference in the cost between the summit and amorphous ones - with the nano-X being close to double the summit ones. Yikes!
TIA and all that.
Dave

SUMMIT
AMOURPHOUS
NANO-X
 

paulbottlehead

Active Member
I notice that the primary inductance goes down a little bit every time the core materials change, and for that consideration alone I have not ordered amorphous or nano-x cores on any of my Monolith purchases.
 
Disclaimer: my direct experience is limited, as it will be for most DIYers. I’ve had a few discussions with winders and read a bit regarding this very question, without deliving into the science and engineering.

If it were me, I’d stick with the better hi-b types (like the Summit series) or step up to a quality nanocrystalline core. Amorphous seem to have a strong flavour even when done well. Monolith, to my way of thinking, are a very good winder for audio at the moment and they will know how to get a good result from either core type. Their products look professional too.
 
I notice that the primary inductance goes down a little bit every time the core materials change, and for that consideration alone I have not ordered amorphous or nano-x cores on any of my Monolith purchases.
I’m not surprised Paul. J&K Audio (who I use) apply different mathematical models, winding techniques, core size etc. for roughly equivalent transformers in different core types. Their nanocrystalline cores are larger for similar ”on paper” performance... and then I choose the oversized core option for better performance. Apparently, it is more difficult to achieve wide bandwidth using nanocrystalline cores.
 
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jmathers

Junior Member
I know nothing about this manufacturer though the website looks impressive. And reading the marketing blurbs was, erm, interesting. How can you resist the "virginal PTFE" in the amorphous and Nano-X core transformers? Come on, "absolute sonic purity and unseen specifications." I say pony up the extra cash for amorphous or Nano-X. :p
 

Wntrmute2

Not So Mediocre Member
I know nothing about this manufacturer though the website looks impressive. And reading the marketing blurbs was, erm, interesting. How can you resist the "virginal PTFE" in the amorphous and Nano-X core transformers? Come on, "absolute sonic purity and unseen specifications." I say pony up the extra cash for amorphous or Nano-X. :p
Hum, do I detect a little tongue in cheek there Mr. Mathers? Seems out of character. I'm not sure my hearing is up to 750 Euro per OT.
:rolleyes:
 
I know nothing about this manufacturer though the website looks impressive. And reading the marketing blurbs was, erm, interesting. How can you resist the "virginal PTFE" in the amorphous and Nano-X core transformers? Come on, "absolute sonic purity and unseen specifications." I say pony up the extra cash for amorphous or Nano-X. :p
Remembering that English is not their first language, they over-egged the description for me too. However, that is just their way of delivering an intended message - it certainly doesn't convince to buy them, but I wouldn't discount them on the basis of that. Many of their designs are well regarded by somewhat conservative EE types and users have reported positive results. I suspect that the Summit series are fine indeed, despite the hyperbole on their website.
 
I'm sort of inclined towards the Summit offering. I'll never know the difference.
Well, I reckon I’d probably prefer the Summit over their amorphous. YMMV. And the Summits represent the peak of their capability using hi-b core material, which I suspect is their strength. We really are talking very high quality transformers here.
 
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Question regarding noise blocking networks (between 0V singnal and chassis). I know these have been discussed but I'm finding it difficult to locate specifics, so asking here. These networks comprise 100 - 470nF capacitor, a 5W 10R resistor and diodes back-to-back (or a bridge). My question is, how do we determine the voltage required for the capacitor and diodes - I assume high voltage capability is not needed?...

These should not be needed for my next build, but I might add the parts to an order, just in case.
 
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paulbottlehead

Active Member
The diodes need to be able to pass enough peak current to trip your circuit breaker if things go south in the amp. I suggest ensuring at least 20A of peak current rating and do not use a Schottky type.

The capacitor should be a ceramic type (I usually use a Z5U).

Voltage is not so concerning here, if you have a major fault the diodes are going to clamp things down until your mains panel pops to stop the carnage.
 
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